diff --git a/Source/Mockolate.SourceGenerators/Sources/Sources.MockClass.cs b/Source/Mockolate.SourceGenerators/Sources/Sources.MockClass.cs
index df1c5cbb..ba5977eb 100644
--- a/Source/Mockolate.SourceGenerators/Sources/Sources.MockClass.cs
+++ b/Source/Mockolate.SourceGenerators/Sources/Sources.MockClass.cs
@@ -661,7 +661,7 @@ static bool TryCastWithDefaultValue<TValue>(object?[] values, int index, TValue
 		memberIds.Emit(sb, "\t\t");
 		sb.AppendLine();
 
-		AppendCreateFastInteractions(sb, "\t\t", @class, memberIds, memberIdPrefix);
+		AppendCreateFastInteractions(sb, "\t\t");
 		sb.AppendLine();
 
 		bool hasMockRegistryProvider = constructors?.Count > 0 || (@class.IsInterface && hasStaticMembers);
@@ -1269,110 +1269,25 @@ static bool TryCastWithDefaultValue<TValue>(object?[] values, int index, TValue
 		return sb.ToString();
 	}
 
-	private static void AppendCreateFastInteractions(StringBuilder sb, string indent, Class @class,
-		MemberIdTable memberIds, string memberIdPrefix)
+	private static void AppendCreateFastInteractions(StringBuilder sb, string indent)
 	{
 		sb.Append(indent).Append("/// <summary>").AppendLine();
 		sb.Append(indent)
 			.Append("///     Creates a <see cref=\"global::Mockolate.Interactions.FastMockInteractions\" /> sized to ")
 			.Append("<see cref=\"MemberCount\" /> for use as the mock's interaction store.").AppendLine();
+		sb.Append(indent)
+			.Append("///     Per-member buffers are not allocated up-front: the recording hot paths call ")
+			.Append("<see cref=\"global::Mockolate.Interactions.FastMockInteractions.GetOrCreateBuffer{TBuffer}(int, global::System.Func{global::Mockolate.Interactions.FastMockInteractions, TBuffer})\" />")
+			.Append(" so a slot is materialized only when its member is first invoked.").AppendLine();
 		sb.Append(indent).Append("/// </summary>").AppendLine();
 		sb.Append(indent)
 			.Append(
 				"internal static global::Mockolate.Interactions.FastMockInteractions CreateFastInteractions(global::Mockolate.MockBehavior behavior)")
 			.AppendLine();
-		sb.Append(indent).Append("{").AppendLine();
 		sb.Append(indent)
 			.Append(
-				"\tglobal::Mockolate.Interactions.FastMockInteractions fast = new global::Mockolate.Interactions.FastMockInteractions(MemberCount, behavior.SkipInteractionRecording);")
+				"\t=> new global::Mockolate.Interactions.FastMockInteractions(MemberCount, behavior.SkipInteractionRecording);")
 			.AppendLine();
-
-		foreach (Method method in @class.AllMethods())
-		{
-			if (!IsFastBufferEligibleMethod(method))
-			{
-				continue;
-			}
-
-			string memberIdRef = memberIdPrefix + memberIds.GetMethodIdentifier(method);
-			int arity = method.Parameters.Count;
-			string typeArgs = arity == 0
-				? string.Empty
-				: "<" + string.Join(", ", method.Parameters.Select(p => p.ToTypeOrWrapper())) + ">";
-
-			if (arity <= 4)
-			{
-				sb.Append(indent).Append("\tglobal::Mockolate.Interactions.FastMethodBufferFactory.InstallMethod")
-					.Append(typeArgs).Append("(fast, ").Append(memberIdRef).Append(");").AppendLine();
-			}
-			else
-			{
-				sb.Append(indent)
-					.Append("\tfast.InstallBuffer(").Append(memberIdRef)
-					.Append(", new global::Mockolate.Interactions.FastMethod").Append(arity)
-					.Append("Buffer").Append(typeArgs).Append("(fast));").AppendLine();
-			}
-		}
-
-		foreach (Property property in @class.AllProperties().Where(p => !p.IsIndexer))
-		{
-			if (!IsFastBufferEligibleProperty(property))
-			{
-				continue;
-			}
-
-			string getMemberIdRef = memberIdPrefix + memberIds.GetPropertyGetIdentifier(property);
-			string accessFieldRef = memberIdPrefix + memberIds.GetPropertyGetterAccessFieldName(property);
-			sb.Append(indent)
-				.Append("\tglobal::Mockolate.Interactions.FastPropertyBufferFactory.InstallPropertyGetter(fast, ")
-				.Append(getMemberIdRef).Append(", ").Append(accessFieldRef).Append(");").AppendLine();
-
-			string setMemberIdRef = memberIdPrefix + memberIds.GetPropertySetIdentifier(property);
-			string propertyType = property.Type.ToTypeOrWrapper();
-			sb.Append(indent)
-				.Append("\tglobal::Mockolate.Interactions.FastPropertyBufferFactory.InstallPropertySetter<")
-				.Append(propertyType).Append(">(fast, ").Append(setMemberIdRef).Append(");").AppendLine();
-		}
-
-		foreach (Property indexer in @class.AllProperties().Where(p => p.IsIndexer))
-		{
-			if (!IsFastBufferEligibleIndexer(indexer))
-			{
-				continue;
-			}
-
-			string getMemberIdRef = memberIdPrefix + memberIds.GetIndexerGetIdentifier(indexer);
-			string setMemberIdRef = memberIdPrefix + memberIds.GetIndexerSetIdentifier(indexer);
-			string indexerKeyTypeArgs =
-				string.Join(", ", indexer.IndexerParameters!.Value.Select(p => p.ToTypeOrWrapper()));
-			string indexerValueType = indexer.Type.ToTypeOrWrapper();
-
-			sb.Append(indent).Append("\tglobal::Mockolate.Interactions.FastIndexerBufferFactory.InstallIndexerGetter<")
-				.Append(indexerKeyTypeArgs).Append(">(fast, ").Append(getMemberIdRef).Append(");").AppendLine();
-			sb.Append(indent).Append("\tglobal::Mockolate.Interactions.FastIndexerBufferFactory.InstallIndexerSetter<")
-				.Append(indexerKeyTypeArgs).Append(", ").Append(indexerValueType).Append(">(fast, ")
-				.Append(setMemberIdRef).Append(");").AppendLine();
-		}
-
-		foreach (Event @event in @class.AllEvents())
-		{
-			if (!IsFastBufferEligibleEvent(@event))
-			{
-				continue;
-			}
-
-			string subMemberIdRef = memberIdPrefix + memberIds.GetEventSubscribeIdentifier(@event);
-			string unsubMemberIdRef = memberIdPrefix + memberIds.GetEventUnsubscribeIdentifier(@event);
-			sb.Append(indent)
-				.Append("\tglobal::Mockolate.Interactions.FastEventBufferFactory.InstallEventSubscribe(fast, ")
-				.Append(subMemberIdRef).Append(");").AppendLine();
-			sb.Append(indent)
-				.Append("\tglobal::Mockolate.Interactions.FastEventBufferFactory.InstallEventUnsubscribe(fast, ")
-				.Append(unsubMemberIdRef).Append(");").AppendLine();
-		}
-
-		sb.Append(indent).Append("\treturn fast;").AppendLine();
-		sb.Append(indent).Append("}").AppendLine();
 	}
 
 	/// <summary>
@@ -1432,30 +1347,32 @@ private static void AppendCachedFieldDeclarations(StringBuilder sb, string inden
 			string indexerValueType = indexer.Type.ToTypeOrWrapper();
 			string getMemberIdRef = memberIdPrefix + memberIds.GetIndexerGetIdentifier(indexer);
 			string setMemberIdRef = memberIdPrefix + memberIds.GetIndexerSetIdentifier(indexer);
+			string getterBufferType = "global::Mockolate.Interactions.FastIndexerGetterBuffer<"
+			                          + indexerKeyTypeArgs + ">";
+			string setterBufferType = "global::Mockolate.Interactions.FastIndexerSetterBuffer<"
+			                          + indexerKeyTypeArgs + ", " + indexerValueType + ">";
 
 			sb.Append(indent)
 				.Append(
 					"[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]")
 				.AppendLine();
-			sb.Append(indent).Append("private global::Mockolate.Interactions.FastIndexerGetterBuffer<")
-				.Append(indexerKeyTypeArgs).Append("> ")
+			sb.Append(indent).Append("private ").Append(getterBufferType).Append(' ')
 				.Append(memberIds.GetIndexerGetterBufferFieldName(indexer)).AppendLine();
-			sb.Append(indent).Append("\t=> field ?? (field = (global::Mockolate.Interactions.FastIndexerGetterBuffer<")
-				.Append(indexerKeyTypeArgs).Append(">)((global::Mockolate.Interactions.FastMockInteractions)")
-				.Append(mockRegistryRef).Append(".Interactions).Buffers[").Append(getMemberIdRef).Append("]!);")
-				.AppendLine();
+			sb.Append(indent).Append("\t=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)")
+				.Append(mockRegistryRef).Append(".Interactions).GetOrCreateBuffer<").Append(getterBufferType)
+				.Append(">(").Append(getMemberIdRef).Append(", static fast => new ").Append(getterBufferType)
+				.Append("(fast)));").AppendLine();
 
 			sb.Append(indent)
 				.Append(
 					"[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]")
 				.AppendLine();
-			sb.Append(indent).Append("private global::Mockolate.Interactions.FastIndexerSetterBuffer<")
-				.Append(indexerKeyTypeArgs).Append(", ").Append(indexerValueType).Append("> ")
+			sb.Append(indent).Append("private ").Append(setterBufferType).Append(' ')
 				.Append(memberIds.GetIndexerSetterBufferFieldName(indexer)).AppendLine();
-			sb.Append(indent).Append("\t=> field ?? (field = (global::Mockolate.Interactions.FastIndexerSetterBuffer<")
-				.Append(indexerKeyTypeArgs).Append(", ").Append(indexerValueType)
-				.Append(">)((global::Mockolate.Interactions.FastMockInteractions)").Append(mockRegistryRef)
-				.Append(".Interactions).Buffers[").Append(setMemberIdRef).Append("]!);").AppendLine();
+			sb.Append(indent).Append("\t=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)")
+				.Append(mockRegistryRef).Append(".Interactions).GetOrCreateBuffer<").Append(setterBufferType)
+				.Append(">(").Append(setMemberIdRef).Append(", static fast => new ").Append(setterBufferType)
+				.Append("(fast)));").AppendLine();
 		}
 
 		foreach (Method method in @class.AllMethods())
@@ -1470,17 +1387,17 @@ private static void AppendCachedFieldDeclarations(StringBuilder sb, string inden
 				? string.Empty
 				: "<" + string.Join(", ", method.Parameters.Select(p => p.ToTypeOrWrapper())) + ">";
 			string memberIdRef = memberIdPrefix + memberIds.GetMethodIdentifier(method);
+			string bufferType = "global::Mockolate.Interactions.FastMethod" + arity + "Buffer" + typeArgs;
 			sb.Append(indent)
 				.Append(
 					"[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]")
 				.AppendLine();
-			sb.Append(indent).Append("private global::Mockolate.Interactions.FastMethod").Append(arity)
-				.Append("Buffer").Append(typeArgs).Append(' ')
+			sb.Append(indent).Append("private ").Append(bufferType).Append(' ')
 				.Append(memberIds.GetMethodBufferFieldName(method)).AppendLine();
-			sb.Append(indent).Append("\t=> field ?? (field = (global::Mockolate.Interactions.FastMethod").Append(arity)
-				.Append("Buffer").Append(typeArgs).Append(")((global::Mockolate.Interactions.FastMockInteractions)")
-				.Append(mockRegistryRef).Append(".Interactions).Buffers[").Append(memberIdRef).Append("]!);")
-				.AppendLine();
+			sb.Append(indent).Append("\t=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)")
+				.Append(mockRegistryRef).Append(".Interactions).GetOrCreateBuffer<").Append(bufferType)
+				.Append(">(").Append(memberIdRef).Append(", static fast => new ").Append(bufferType)
+				.Append("(fast)));").AppendLine();
 		}
 	}
 
@@ -1553,7 +1470,6 @@ private static bool IsFastBufferEligibleMethod(Method method)
 	///     constraint, and <c>where T : default</c> (CS8822) conflicts with those constraints.
 	///     Without a constraint clause the compiler resolves the bare <c>T?</c> as
 	///     <c>Nullable&lt;T&gt;</c> and reports CS0453/CS9334/CS0738/CS0266.
-	///
 	///     The fix is to drop the trailing <c>?</c> from the setup-side return type
 	///     (<c>IReturnMethodSetup&lt;T&gt;</c> instead of <c>IReturnMethodSetup&lt;T?&gt;</c>) and from
 	///     the matching <c>ReturnMethodSetup&lt;T&gt;</c> construction. NRT annotations are erased at
@@ -3109,8 +3025,10 @@ private static void AppendMockSubject_ImplementClass_AddMethod(StringBuilder sb,
 				: "<" + string.Join(", ", method.Parameters.Select(p => p.ToTypeOrWrapper())) + ">";
 			string bufferType = $"global::Mockolate.Interactions.FastMethod{arity}Buffer{typeArgs}";
 
-			sb.Append("\t\t\t\t((").Append(bufferType).Append(")((global::Mockolate.Interactions.FastMockInteractions)")
-				.Append(mockRegistry).Append(".Interactions).Buffers[").Append(memberIdRef).Append("]!).Append(")
+			sb.Append("\t\t\t\t((global::Mockolate.Interactions.FastMockInteractions)")
+				.Append(mockRegistry).Append(".Interactions).GetOrCreateBuffer<").Append(bufferType)
+				.Append(">(").Append(memberIdRef).Append(", static fast => new ").Append(bufferType)
+				.Append("(fast)).Append(")
 				.Append(method.GetUniqueNameString());
 			if (arity > 0)
 			{
diff --git a/Source/Mockolate.SourceGenerators/Sources/Sources.cs b/Source/Mockolate.SourceGenerators/Sources/Sources.cs
index be487fbc..6c891623 100644
--- a/Source/Mockolate.SourceGenerators/Sources/Sources.cs
+++ b/Source/Mockolate.SourceGenerators/Sources/Sources.cs
@@ -149,11 +149,14 @@ private static void EmitIndexerGetterAccessAndSetup(StringBuilder sb, string ind
 		}
 		else if (useFastBuffers && memberIdRef is not null)
 		{
-			sb.Append(indent).Append("\t((global::Mockolate.Interactions.FastIndexerGetterBuffer<");
-			AppendIndexerParameterTypes(sb, parameters);
-			sb.Append(">)((global::Mockolate.Interactions.FastMockInteractions)").Append(mockRegistry)
-				.Append(".Interactions).Buffers[").Append(memberIdRef).Append("]!).Append(")
-				.Append(accessVarName).Append(");").AppendLine();
+			StringBuilder bufferType = new("global::Mockolate.Interactions.FastIndexerGetterBuffer<");
+			AppendIndexerParameterTypes(bufferType, parameters);
+			bufferType.Append('>');
+			string bufferTypeName = bufferType.ToString();
+			sb.Append(indent).Append("\t((global::Mockolate.Interactions.FastMockInteractions)").Append(mockRegistry)
+				.Append(".Interactions).GetOrCreateBuffer<").Append(bufferTypeName).Append(">(")
+				.Append(memberIdRef).Append(", static fast => new ").Append(bufferTypeName)
+				.Append("(fast)).Append(").Append(accessVarName).Append(");").AppendLine();
 		}
 		else
 		{
@@ -241,12 +244,14 @@ private static void EmitIndexerSetterAccessAndSetup(StringBuilder sb, string ind
 		}
 		else if (useFastBuffers && memberIdRef is not null)
 		{
-			sb.Append(indent).Append("\t((global::Mockolate.Interactions.FastIndexerSetterBuffer<");
-			AppendIndexerParameterTypes(sb, parameters);
-			sb.Append(", ").AppendTypeOrWrapper(propertyType)
-				.Append(">)((global::Mockolate.Interactions.FastMockInteractions)").Append(mockRegistry)
-				.Append(".Interactions).Buffers[").Append(memberIdRef).Append("]!).Append(")
-				.Append(accessVarName).Append(");").AppendLine();
+			StringBuilder bufferType = new("global::Mockolate.Interactions.FastIndexerSetterBuffer<");
+			AppendIndexerParameterTypes(bufferType, parameters);
+			bufferType.Append(", ").AppendTypeOrWrapper(propertyType).Append('>');
+			string bufferTypeName = bufferType.ToString();
+			sb.Append(indent).Append("\t((global::Mockolate.Interactions.FastMockInteractions)").Append(mockRegistry)
+				.Append(".Interactions).GetOrCreateBuffer<").Append(bufferTypeName).Append(">(")
+				.Append(memberIdRef).Append(", static fast => new ").Append(bufferTypeName)
+				.Append("(fast)).Append(").Append(accessVarName).Append(");").AppendLine();
 		}
 		else
 		{
diff --git a/Source/Mockolate/Interactions/FastEventBuffer.cs b/Source/Mockolate/Interactions/FastEventBuffer.cs
index 9ca71f01..46cc749b 100644
--- a/Source/Mockolate/Interactions/FastEventBuffer.cs
+++ b/Source/Mockolate/Interactions/FastEventBuffer.cs
@@ -31,7 +31,12 @@ public sealed class FastEventBuffer : IFastMemberBuffer
 	private readonly FastEventBufferKind _kind;
 	private readonly ChunkedSlotStorage<Record> _storage = new();
 
-	internal FastEventBuffer(FastMockInteractions owner, FastEventBufferKind kind)
+	/// <summary>
+	///     Creates a new event buffer of the given <paramref name="kind" /> attached to <paramref name="owner" />.
+	/// </summary>
+	/// <param name="owner">The mock-wide <see cref="FastMockInteractions" /> the buffer publishes records into.</param>
+	/// <param name="kind">Distinguishes a subscribe-recording buffer from an unsubscribe-recording buffer.</param>
+	public FastEventBuffer(FastMockInteractions owner, FastEventBufferKind kind)
 	{
 		_owner = owner;
 		_kind = kind;
@@ -132,28 +137,3 @@ internal struct Record
 	}
 }
 
-/// <summary>
-///     Factory helpers for event buffers.
-/// </summary>
-public static class FastEventBufferFactory
-{
-	/// <summary>
-	///     Creates and installs an event subscribe buffer at the given <paramref name="memberId" />.
-	/// </summary>
-	public static FastEventBuffer InstallEventSubscribe(this FastMockInteractions interactions, int memberId)
-	{
-		FastEventBuffer buffer = new(interactions, FastEventBufferKind.Subscribe);
-		interactions.InstallBuffer(memberId, buffer);
-		return buffer;
-	}
-
-	/// <summary>
-	///     Creates and installs an event unsubscribe buffer at the given <paramref name="memberId" />.
-	/// </summary>
-	public static FastEventBuffer InstallEventUnsubscribe(this FastMockInteractions interactions, int memberId)
-	{
-		FastEventBuffer buffer = new(interactions, FastEventBufferKind.Unsubscribe);
-		interactions.InstallBuffer(memberId, buffer);
-		return buffer;
-	}
-}
diff --git a/Source/Mockolate/Interactions/FastIndexerBuffer.cs b/Source/Mockolate/Interactions/FastIndexerBuffer.cs
index 676d3386..3ba3871b 100644
--- a/Source/Mockolate/Interactions/FastIndexerBuffer.cs
+++ b/Source/Mockolate/Interactions/FastIndexerBuffer.cs
@@ -16,7 +16,11 @@ public sealed class FastIndexerGetterBuffer<T1> : IFastMemberBuffer
 	private readonly FastMockInteractions _owner;
 	private readonly ChunkedSlotStorage<Record> _storage = new();
 
-	internal FastIndexerGetterBuffer(FastMockInteractions owner)
+	/// <summary>
+	///     Creates a new indexer-getter buffer attached to <paramref name="owner" />.
+	/// </summary>
+	/// <param name="owner">The mock-wide <see cref="FastMockInteractions" /> the buffer publishes records into.</param>
+	public FastIndexerGetterBuffer(FastMockInteractions owner)
 	{
 		_owner = owner;
 	}
@@ -146,7 +150,11 @@ public sealed class FastIndexerGetterBuffer<T1, T2> : IFastMemberBuffer
 	private readonly FastMockInteractions _owner;
 	private readonly ChunkedSlotStorage<Record> _storage = new();
 
-	internal FastIndexerGetterBuffer(FastMockInteractions owner)
+	/// <summary>
+	///     Creates a new indexer-getter buffer attached to <paramref name="owner" />.
+	/// </summary>
+	/// <param name="owner">The mock-wide <see cref="FastMockInteractions" /> the buffer publishes records into.</param>
+	public FastIndexerGetterBuffer(FastMockInteractions owner)
 	{
 		_owner = owner;
 	}
@@ -275,7 +283,11 @@ public sealed class FastIndexerGetterBuffer<T1, T2, T3> : IFastMemberBuffer
 	private readonly FastMockInteractions _owner;
 	private readonly ChunkedSlotStorage<Record> _storage = new();
 
-	internal FastIndexerGetterBuffer(FastMockInteractions owner)
+	/// <summary>
+	///     Creates a new indexer-getter buffer attached to <paramref name="owner" />.
+	/// </summary>
+	/// <param name="owner">The mock-wide <see cref="FastMockInteractions" /> the buffer publishes records into.</param>
+	public FastIndexerGetterBuffer(FastMockInteractions owner)
 	{
 		_owner = owner;
 	}
@@ -407,7 +419,11 @@ public sealed class FastIndexerGetterBuffer<T1, T2, T3, T4> : IFastMemberBuffer
 	private readonly FastMockInteractions _owner;
 	private readonly ChunkedSlotStorage<Record> _storage = new();
 
-	internal FastIndexerGetterBuffer(FastMockInteractions owner)
+	/// <summary>
+	///     Creates a new indexer-getter buffer attached to <paramref name="owner" />.
+	/// </summary>
+	/// <param name="owner">The mock-wide <see cref="FastMockInteractions" /> the buffer publishes records into.</param>
+	public FastIndexerGetterBuffer(FastMockInteractions owner)
 	{
 		_owner = owner;
 	}
@@ -542,7 +558,11 @@ public sealed class FastIndexerSetterBuffer<T1, TValue> : IFastMemberBuffer
 	private readonly FastMockInteractions _owner;
 	private readonly ChunkedSlotStorage<Record> _storage = new();
 
-	internal FastIndexerSetterBuffer(FastMockInteractions owner)
+	/// <summary>
+	///     Creates a new indexer-setter buffer attached to <paramref name="owner" />.
+	/// </summary>
+	/// <param name="owner">The mock-wide <see cref="FastMockInteractions" /> the buffer publishes records into.</param>
+	public FastIndexerSetterBuffer(FastMockInteractions owner)
 	{
 		_owner = owner;
 	}
@@ -672,7 +692,11 @@ public sealed class FastIndexerSetterBuffer<T1, T2, TValue> : IFastMemberBuffer
 	private readonly FastMockInteractions _owner;
 	private readonly ChunkedSlotStorage<Record> _storage = new();
 
-	internal FastIndexerSetterBuffer(FastMockInteractions owner)
+	/// <summary>
+	///     Creates a new indexer-setter buffer attached to <paramref name="owner" />.
+	/// </summary>
+	/// <param name="owner">The mock-wide <see cref="FastMockInteractions" /> the buffer publishes records into.</param>
+	public FastIndexerSetterBuffer(FastMockInteractions owner)
 	{
 		_owner = owner;
 	}
@@ -805,7 +829,11 @@ public sealed class FastIndexerSetterBuffer<T1, T2, T3, TValue> : IFastMemberBuf
 	private readonly FastMockInteractions _owner;
 	private readonly ChunkedSlotStorage<Record> _storage = new();
 
-	internal FastIndexerSetterBuffer(FastMockInteractions owner)
+	/// <summary>
+	///     Creates a new indexer-setter buffer attached to <paramref name="owner" />.
+	/// </summary>
+	/// <param name="owner">The mock-wide <see cref="FastMockInteractions" /> the buffer publishes records into.</param>
+	public FastIndexerSetterBuffer(FastMockInteractions owner)
 	{
 		_owner = owner;
 	}
@@ -941,7 +969,11 @@ public sealed class FastIndexerSetterBuffer<T1, T2, T3, T4, TValue> : IFastMembe
 	private readonly FastMockInteractions _owner;
 	private readonly ChunkedSlotStorage<Record> _storage = new();
 
-	internal FastIndexerSetterBuffer(FastMockInteractions owner)
+	/// <summary>
+	///     Creates a new indexer-setter buffer attached to <paramref name="owner" />.
+	/// </summary>
+	/// <param name="owner">The mock-wide <see cref="FastMockInteractions" /> the buffer publishes records into.</param>
+	public FastIndexerSetterBuffer(FastMockInteractions owner)
 	{
 		_owner = owner;
 	}
@@ -1068,88 +1100,3 @@ internal struct Record
 	}
 }
 
-/// <summary>
-///     Factory helpers for indexer buffers.
-/// </summary>
-public static class FastIndexerBufferFactory
-{
-	/// <summary>
-	///     Creates and installs an indexer getter buffer at the given <paramref name="memberId" />.
-	/// </summary>
-	public static FastIndexerGetterBuffer<T1> InstallIndexerGetter<T1>(this FastMockInteractions interactions, int memberId)
-	{
-		FastIndexerGetterBuffer<T1> buffer = new(interactions);
-		interactions.InstallBuffer(memberId, buffer);
-		return buffer;
-	}
-
-	/// <summary>
-	///     Creates and installs an indexer getter buffer at the given <paramref name="memberId" />.
-	/// </summary>
-	public static FastIndexerGetterBuffer<T1, T2> InstallIndexerGetter<T1, T2>(this FastMockInteractions interactions, int memberId)
-	{
-		FastIndexerGetterBuffer<T1, T2> buffer = new(interactions);
-		interactions.InstallBuffer(memberId, buffer);
-		return buffer;
-	}
-
-	/// <summary>
-	///     Creates and installs an indexer getter buffer at the given <paramref name="memberId" />.
-	/// </summary>
-	public static FastIndexerGetterBuffer<T1, T2, T3> InstallIndexerGetter<T1, T2, T3>(this FastMockInteractions interactions, int memberId)
-	{
-		FastIndexerGetterBuffer<T1, T2, T3> buffer = new(interactions);
-		interactions.InstallBuffer(memberId, buffer);
-		return buffer;
-	}
-
-	/// <summary>
-	///     Creates and installs an indexer getter buffer at the given <paramref name="memberId" />.
-	/// </summary>
-	public static FastIndexerGetterBuffer<T1, T2, T3, T4> InstallIndexerGetter<T1, T2, T3, T4>(this FastMockInteractions interactions, int memberId)
-	{
-		FastIndexerGetterBuffer<T1, T2, T3, T4> buffer = new(interactions);
-		interactions.InstallBuffer(memberId, buffer);
-		return buffer;
-	}
-
-	/// <summary>
-	///     Creates and installs an indexer setter buffer at the given <paramref name="memberId" />.
-	/// </summary>
-	public static FastIndexerSetterBuffer<T1, TValue> InstallIndexerSetter<T1, TValue>(this FastMockInteractions interactions, int memberId)
-	{
-		FastIndexerSetterBuffer<T1, TValue> buffer = new(interactions);
-		interactions.InstallBuffer(memberId, buffer);
-		return buffer;
-	}
-
-	/// <summary>
-	///     Creates and installs an indexer setter buffer at the given <paramref name="memberId" />.
-	/// </summary>
-	public static FastIndexerSetterBuffer<T1, T2, TValue> InstallIndexerSetter<T1, T2, TValue>(this FastMockInteractions interactions, int memberId)
-	{
-		FastIndexerSetterBuffer<T1, T2, TValue> buffer = new(interactions);
-		interactions.InstallBuffer(memberId, buffer);
-		return buffer;
-	}
-
-	/// <summary>
-	///     Creates and installs an indexer setter buffer at the given <paramref name="memberId" />.
-	/// </summary>
-	public static FastIndexerSetterBuffer<T1, T2, T3, TValue> InstallIndexerSetter<T1, T2, T3, TValue>(this FastMockInteractions interactions, int memberId)
-	{
-		FastIndexerSetterBuffer<T1, T2, T3, TValue> buffer = new(interactions);
-		interactions.InstallBuffer(memberId, buffer);
-		return buffer;
-	}
-
-	/// <summary>
-	///     Creates and installs an indexer setter buffer at the given <paramref name="memberId" />.
-	/// </summary>
-	public static FastIndexerSetterBuffer<T1, T2, T3, T4, TValue> InstallIndexerSetter<T1, T2, T3, T4, TValue>(this FastMockInteractions interactions, int memberId)
-	{
-		FastIndexerSetterBuffer<T1, T2, T3, T4, TValue> buffer = new(interactions);
-		interactions.InstallBuffer(memberId, buffer);
-		return buffer;
-	}
-}
diff --git a/Source/Mockolate/Interactions/FastMethodBuffer.cs b/Source/Mockolate/Interactions/FastMethodBuffer.cs
index 6a64010f..5e37107b 100644
--- a/Source/Mockolate/Interactions/FastMethodBuffer.cs
+++ b/Source/Mockolate/Interactions/FastMethodBuffer.cs
@@ -16,7 +16,11 @@ public sealed class FastMethod0Buffer : IFastMemberBuffer
 	private readonly FastMockInteractions _owner;
 	private readonly ChunkedSlotStorage<Record> _storage = new();
 
-	internal FastMethod0Buffer(FastMockInteractions owner)
+	/// <summary>
+	///     Creates a new parameterless method buffer attached to <paramref name="owner" />.
+	/// </summary>
+	/// <param name="owner">The mock-wide <see cref="FastMockInteractions" /> the buffer publishes records into.</param>
+	public FastMethod0Buffer(FastMockInteractions owner)
 	{
 		_owner = owner;
 	}
@@ -122,7 +126,11 @@ public sealed class FastMethod1Buffer<T1> : IFastMemberBuffer
 	private readonly FastMockInteractions _owner;
 	private readonly ChunkedSlotStorage<Record> _storage = new();
 
-	internal FastMethod1Buffer(FastMockInteractions owner)
+	/// <summary>
+	///     Creates a new 1-parameter method buffer attached to <paramref name="owner" />.
+	/// </summary>
+	/// <param name="owner">The mock-wide <see cref="FastMockInteractions" /> the buffer publishes records into.</param>
+	public FastMethod1Buffer(FastMockInteractions owner)
 	{
 		_owner = owner;
 	}
@@ -248,7 +256,11 @@ public sealed class FastMethod2Buffer<T1, T2> : IFastMemberBuffer
 	private readonly FastMockInteractions _owner;
 	private readonly ChunkedSlotStorage<Record> _storage = new();
 
-	internal FastMethod2Buffer(FastMockInteractions owner)
+	/// <summary>
+	///     Creates a new 2-parameter method buffer attached to <paramref name="owner" />.
+	/// </summary>
+	/// <param name="owner">The mock-wide <see cref="FastMockInteractions" /> the buffer publishes records into.</param>
+	public FastMethod2Buffer(FastMockInteractions owner)
 	{
 		_owner = owner;
 	}
@@ -374,7 +386,11 @@ public sealed class FastMethod3Buffer<T1, T2, T3> : IFastMemberBuffer
 	private readonly FastMockInteractions _owner;
 	private readonly ChunkedSlotStorage<Record> _storage = new();
 
-	internal FastMethod3Buffer(FastMockInteractions owner)
+	/// <summary>
+	///     Creates a new 3-parameter method buffer attached to <paramref name="owner" />.
+	/// </summary>
+	/// <param name="owner">The mock-wide <see cref="FastMockInteractions" /> the buffer publishes records into.</param>
+	public FastMethod3Buffer(FastMockInteractions owner)
 	{
 		_owner = owner;
 	}
@@ -501,7 +517,11 @@ public sealed class FastMethod4Buffer<T1, T2, T3, T4> : IFastMemberBuffer
 	private readonly FastMockInteractions _owner;
 	private readonly ChunkedSlotStorage<Record> _storage = new();
 
-	internal FastMethod4Buffer(FastMockInteractions owner)
+	/// <summary>
+	///     Creates a new 4-parameter method buffer attached to <paramref name="owner" />.
+	/// </summary>
+	/// <param name="owner">The mock-wide <see cref="FastMockInteractions" /> the buffer publishes records into.</param>
+	public FastMethod4Buffer(FastMockInteractions owner)
 	{
 		_owner = owner;
 	}
@@ -618,59 +638,3 @@ internal struct Record
 	}
 }
 
-/// <summary>
-///     Factory helpers that hide the per-arity buffer constructors behind the
-///     <see cref="FastMockInteractions" /> API.
-/// </summary>
-public static class FastMethodBufferFactory
-{
-	/// <summary>
-	///     Creates and installs a parameterless method buffer at the given <paramref name="memberId" />.
-	/// </summary>
-	public static FastMethod0Buffer InstallMethod(this FastMockInteractions interactions, int memberId)
-	{
-		FastMethod0Buffer buffer = new(interactions);
-		interactions.InstallBuffer(memberId, buffer);
-		return buffer;
-	}
-
-	/// <summary>
-	///     Creates and installs a 1-parameter method buffer at the given <paramref name="memberId" />.
-	/// </summary>
-	public static FastMethod1Buffer<T1> InstallMethod<T1>(this FastMockInteractions interactions, int memberId)
-	{
-		FastMethod1Buffer<T1> buffer = new(interactions);
-		interactions.InstallBuffer(memberId, buffer);
-		return buffer;
-	}
-
-	/// <summary>
-	///     Creates and installs a 2-parameter method buffer at the given <paramref name="memberId" />.
-	/// </summary>
-	public static FastMethod2Buffer<T1, T2> InstallMethod<T1, T2>(this FastMockInteractions interactions, int memberId)
-	{
-		FastMethod2Buffer<T1, T2> buffer = new(interactions);
-		interactions.InstallBuffer(memberId, buffer);
-		return buffer;
-	}
-
-	/// <summary>
-	///     Creates and installs a 3-parameter method buffer at the given <paramref name="memberId" />.
-	/// </summary>
-	public static FastMethod3Buffer<T1, T2, T3> InstallMethod<T1, T2, T3>(this FastMockInteractions interactions, int memberId)
-	{
-		FastMethod3Buffer<T1, T2, T3> buffer = new(interactions);
-		interactions.InstallBuffer(memberId, buffer);
-		return buffer;
-	}
-
-	/// <summary>
-	///     Creates and installs a 4-parameter method buffer at the given <paramref name="memberId" />.
-	/// </summary>
-	public static FastMethod4Buffer<T1, T2, T3, T4> InstallMethod<T1, T2, T3, T4>(this FastMockInteractions interactions, int memberId)
-	{
-		FastMethod4Buffer<T1, T2, T3, T4> buffer = new(interactions);
-		interactions.InstallBuffer(memberId, buffer);
-		return buffer;
-	}
-}
diff --git a/Source/Mockolate/Interactions/FastMockInteractions.cs b/Source/Mockolate/Interactions/FastMockInteractions.cs
index 1f529614..522e3a82 100644
--- a/Source/Mockolate/Interactions/FastMockInteractions.cs
+++ b/Source/Mockolate/Interactions/FastMockInteractions.cs
@@ -29,8 +29,8 @@ public class FastMockInteractions : IMockInteractions
 
 	/// <summary>
 	///     Creates a new <see cref="FastMockInteractions" /> sized to <paramref name="memberCount" />.
-	///     Each mockable member is later assigned its own per-member buffer at the matching index via
-	///     <see cref="InstallBuffer(int, IFastMemberBuffer)" />.
+	///     Each mockable member's buffer slot starts empty and is materialized lazily on first access via
+	///     <see cref="GetOrCreateBuffer{TBuffer}(int, Func{FastMockInteractions, TBuffer})" />.
 	/// </summary>
 	/// <param name="memberCount">The number of distinct mockable members the buffer array should hold.</param>
 	/// <param name="skipInteractionRecording">Mirrors <see cref="MockBehavior.SkipInteractionRecording" />.</param>
@@ -70,13 +70,59 @@ public FastMockInteractions(int memberCount, bool skipInteractionRecording = fal
 	public int Count => (int)Interlocked.Read(ref _globalSequence);
 
 	/// <summary>
-	///     Installs <paramref name="buffer" /> at the slot matching <paramref name="memberId" />.
-	///     Called once at mock construction by the source generator.
+	///     Returns the buffer at <paramref name="memberId" />, materializing it via <paramref name="factory" />
+	///     under a lock-free CAS on first touch. The factory must be a static lambda so the runtime never
+	///     allocates a closure on the lazy path.
 	/// </summary>
+	/// <typeparam name="TBuffer">The concrete buffer type at the slot.</typeparam>
 	/// <param name="memberId">The generator-emitted member id for the buffer's target member.</param>
-	/// <param name="buffer">The per-member buffer to install.</param>
-	public void InstallBuffer(int memberId, IFastMemberBuffer buffer)
-		=> Buffers[memberId] = buffer;
+	/// <param name="factory">
+	///     Builds a new buffer when the slot is still empty. Invoked at most once per slot in the absence
+	///     of a race; under contention the loser's allocation is discarded and the winner is returned.
+	/// </param>
+	public TBuffer GetOrCreateBuffer<TBuffer>(int memberId, Func<FastMockInteractions, TBuffer> factory)
+		where TBuffer : class, IFastMemberBuffer
+	{
+		IFastMemberBuffer?[] buffers = Buffers;
+		IFastMemberBuffer? existing = Volatile.Read(ref buffers[memberId]);
+		if (existing is TBuffer typed)
+		{
+			return typed;
+		}
+
+		TBuffer created = factory(this);
+		IFastMemberBuffer? prev = Interlocked.CompareExchange(ref buffers[memberId], created, null);
+		return prev is TBuffer winner ? winner : created;
+	}
+
+	/// <summary>
+	///     <typeparamref name="TState" />-passing variant of
+	///     <see cref="GetOrCreateBuffer{TBuffer}(int, Func{FastMockInteractions, TBuffer})" /> that lets
+	///     callers supply the buffer's construction parameter without allocating a closure.
+	/// </summary>
+	/// <typeparam name="TBuffer">The concrete buffer type at the slot.</typeparam>
+	/// <typeparam name="TState">Type of the construction parameter forwarded to <paramref name="factory" />.</typeparam>
+	/// <param name="memberId">The generator-emitted member id for the buffer's target member.</param>
+	/// <param name="factory">
+	///     Builds a new buffer from <paramref name="state" /> when the slot is still empty. Must be a
+	///     static lambda; <paramref name="state" /> is the only flow path so closures are unnecessary.
+	/// </param>
+	/// <param name="state">Forwarded to <paramref name="factory" /> on construction.</param>
+	public TBuffer GetOrCreateBuffer<TBuffer, TState>(int memberId,
+		Func<FastMockInteractions, TState, TBuffer> factory, TState state)
+		where TBuffer : class, IFastMemberBuffer
+	{
+		IFastMemberBuffer?[] buffers = Buffers;
+		IFastMemberBuffer? existing = Volatile.Read(ref buffers[memberId]);
+		if (existing is TBuffer typed)
+		{
+			return typed;
+		}
+
+		TBuffer created = factory(this, state);
+		IFastMemberBuffer? prev = Interlocked.CompareExchange(ref buffers[memberId], created, null);
+		return prev is TBuffer winner ? winner : created;
+	}
 
 	/// <summary>
 	///     Reserves the next sequence number for a recording. Buffer implementations call this once
diff --git a/Source/Mockolate/Interactions/FastPropertyBuffer.cs b/Source/Mockolate/Interactions/FastPropertyBuffer.cs
index 4180acd0..d2920980 100644
--- a/Source/Mockolate/Interactions/FastPropertyBuffer.cs
+++ b/Source/Mockolate/Interactions/FastPropertyBuffer.cs
@@ -1,4 +1,3 @@
-using System;
 using System.Collections.Generic;
 using System.Diagnostics;
 using Mockolate.Parameters;
@@ -24,14 +23,15 @@ public sealed class FastPropertyGetterBuffer : IFastMemberBuffer
 {
 	private readonly FastMockInteractions _owner;
 	private readonly ChunkedSlotStorage<Record> _storage = new();
-	private PropertyGetterAccess? _access;
+	private readonly PropertyGetterAccess _access;
 
-	internal FastPropertyGetterBuffer(FastMockInteractions owner)
-	{
-		_owner = owner;
-	}
-
-	internal FastPropertyGetterBuffer(FastMockInteractions owner, PropertyGetterAccess access)
+	/// <summary>
+	///     Creates a new property-getter buffer pre-seeded with the shared
+	///     <see cref="PropertyGetterAccess" /> <paramref name="access" /> singleton.
+	/// </summary>
+	/// <param name="owner">The mock-wide <see cref="FastMockInteractions" /> the buffer publishes records into.</param>
+	/// <param name="access">The shared <see cref="PropertyGetterAccess" /> singleton emitted by the source generator.</param>
+	public FastPropertyGetterBuffer(FastMockInteractions owner, PropertyGetterAccess access)
 	{
 		_owner = owner;
 		_access = access;
@@ -42,18 +42,10 @@ internal FastPropertyGetterBuffer(FastMockInteractions owner, PropertyGetterAcce
 
 	/// <summary>
 	///     Records a property getter access using the buffer's pre-seeded
-	///     <see cref="PropertyGetterAccess" /> singleton. Throws when the singleton has not been
-	///     installed — callers must use <see cref="Append(string)" /> in that case.
+	///     <see cref="PropertyGetterAccess" /> singleton.
 	/// </summary>
-	/// <exception cref="InvalidOperationException">No singleton was supplied at install time.</exception>
 	public void Append()
 	{
-		if (_access is null)
-		{
-			throw new InvalidOperationException(
-				$"{nameof(Append)}() requires the buffer to be installed with a {nameof(PropertyGetterAccess)} singleton via {nameof(FastPropertyBufferFactory)}.{nameof(FastPropertyBufferFactory.InstallPropertyGetter)}(memberId, access). Use {nameof(Append)}(string) when no singleton is available.");
-		}
-
 		long seq = _owner.NextSequence();
 		int slot = _storage.Reserve();
 		ref Record r = ref _storage.SlotForWrite(slot);
@@ -66,22 +58,6 @@ public void Append()
 		}
 	}
 
-	/// <summary>
-	///     Records a property getter access. Lazily installs the buffer's
-	///     <see cref="PropertyGetterAccess" /> singleton from <paramref name="name" /> on first
-	///     call so legacy callers (generated code that does not pass a pre-built singleton) keep
-	///     working without allocating one access object per record.
-	/// </summary>
-	public void Append(string name)
-	{
-		// Lazy init: the buffer is bound to a single property, so one singleton covers every
-		// record. The benign race here is acceptable — both instances are equivalent because
-		// PropertyGetterAccess is identified solely by Name; whichever assignment wins still
-		// satisfies the contract.
-		_access ??= new PropertyGetterAccess(name);
-		Append();
-	}
-
 	/// <inheritdoc cref="IFastMemberBuffer.Clear" />
 	public void Clear() => _storage.Clear();
 
@@ -95,7 +71,7 @@ void IFastMemberBuffer.AppendBoxed(List<(long Seq, IInteraction Interaction)> de
 				return;
 			}
 
-			PropertyGetterAccess access = _access!;
+			PropertyGetterAccess access = _access;
 			for (int slot = 0; slot < n; slot++)
 			{
 				ref Record r = ref _storage.SlotUnderLock(slot);
@@ -114,7 +90,7 @@ void IFastMemberBuffer.AppendBoxedUnverified(List<(long Seq, IInteraction Intera
 				return;
 			}
 
-			PropertyGetterAccess access = _access!;
+			PropertyGetterAccess access = _access;
 			for (int slot = 0; slot < n; slot++)
 			{
 				if (_storage.VerifiedUnderLock(slot))
@@ -167,7 +143,11 @@ public sealed class FastPropertySetterBuffer<T> : IFastMemberBuffer
 	private readonly FastMockInteractions _owner;
 	private readonly ChunkedSlotStorage<Record> _storage = new();
 
-	internal FastPropertySetterBuffer(FastMockInteractions owner)
+	/// <summary>
+	///     Creates a new property-setter buffer attached to <paramref name="owner" />.
+	/// </summary>
+	/// <param name="owner">The mock-wide <see cref="FastMockInteractions" /> the buffer publishes records into.</param>
+	public FastPropertySetterBuffer(FastMockInteractions owner)
 	{
 		_owner = owner;
 	}
@@ -266,42 +246,3 @@ internal struct Record
 	}
 }
 
-/// <summary>
-///     Factory helpers for property buffers.
-/// </summary>
-public static class FastPropertyBufferFactory
-{
-	/// <summary>
-	///     Creates and installs a property getter buffer at the given <paramref name="memberId" />.
-	/// </summary>
-	public static FastPropertyGetterBuffer InstallPropertyGetter(this FastMockInteractions interactions, int memberId)
-	{
-		FastPropertyGetterBuffer buffer = new(interactions);
-		interactions.InstallBuffer(memberId, buffer);
-		return buffer;
-	}
-
-	/// <summary>
-	///     Creates and installs a property getter buffer at the given <paramref name="memberId" /> with
-	///     a pre-built shared <paramref name="access" /> singleton. Used by the source generator so the
-	///     buffer never has to allocate a <see cref="PropertyGetterAccess" /> on the first record or on
-	///     verification.
-	/// </summary>
-	public static FastPropertyGetterBuffer InstallPropertyGetter(this FastMockInteractions interactions,
-		int memberId, PropertyGetterAccess access)
-	{
-		FastPropertyGetterBuffer buffer = new(interactions, access);
-		interactions.InstallBuffer(memberId, buffer);
-		return buffer;
-	}
-
-	/// <summary>
-	///     Creates and installs a property setter buffer at the given <paramref name="memberId" />.
-	/// </summary>
-	public static FastPropertySetterBuffer<T> InstallPropertySetter<T>(this FastMockInteractions interactions, int memberId)
-	{
-		FastPropertySetterBuffer<T> buffer = new(interactions);
-		interactions.InstallBuffer(memberId, buffer);
-		return buffer;
-	}
-}
diff --git a/Source/Mockolate/MockRegistry.Interactions.cs b/Source/Mockolate/MockRegistry.Interactions.cs
index 37f3f7ea..bc379d0a 100644
--- a/Source/Mockolate/MockRegistry.Interactions.cs
+++ b/Source/Mockolate/MockRegistry.Interactions.cs
@@ -94,7 +94,7 @@ public void ClearAllInteractions()
 	///     <paramref name="memberId" />, or <see langword="null" /> when no setup has been registered.
 	/// </summary>
 	/// <remarks>
-	///     Property dispatch reads the snapshot via <see cref="GetPropertyFast{TResult}(int, string, System.Func{Mockolate.MockBehavior,TResult}, Func{TResult}?)" />
+	///     Property dispatch reads the snapshot via <see cref="GetPropertyFast{TResult}(int, PropertyGetterAccess, System.Func{Mockolate.MockBehavior,TResult}, Func{TResult}?)" />
 	///     and falls back to the cold path when the snapshot is empty, so this accessor is intended for
 	///     diagnostics and tests that need to verify the fast-path table directly.
 	/// </remarks>
@@ -601,38 +601,18 @@ public TResult GetProperty<TResult>(PropertyGetterAccess access, Func<TResult> d
 	}
 
 	/// <summary>
-	///     Allocation-free fast-path overload of <see cref="GetProperty{TResult}(string, Func{TResult}, Func{TResult}?)" />.
-	///     Avoids the per-call closure allocation by accepting a static <see cref="Func{T, TResult}" /> that takes the
-	///     active <see cref="MockBehavior" /> as its argument — the source generator emits a <c>static</c> lambda so
-	///     the C# compiler caches the delegate in a static field.
-	/// </summary>
-	/// <typeparam name="TResult">The property's value type.</typeparam>
-	/// <param name="memberId">The generator-emitted member id for the property getter.</param>
-	/// <param name="propertyName">The simple property name.</param>
-	/// <param name="defaultValueGenerator">Cached factory invoked with the active <see cref="MockBehavior" /> when a default value is needed.</param>
-	/// <param name="baseValueAccessor">Optional accessor for the base-class getter; when <see langword="null" /> only the default/initial value is considered. Pass <see langword="null" /> for the no-wrapping fast path.</param>
-	/// <returns>The resolved getter value.</returns>
-	/// <exception cref="MockNotSetupException">No setup exists for the property and <see cref="MockBehavior.ThrowWhenNotSetup" /> is <see langword="true" />.</exception>
-	public TResult GetPropertyFast<TResult>(int memberId, string propertyName,
-		Func<MockBehavior, TResult> defaultValueGenerator, Func<TResult>? baseValueAccessor = null)
-	{
-		if (!Behavior.SkipInteractionRecording)
-		{
-			RecordPropertyGetter(memberId, propertyName);
-		}
-
-		return ResolvePropertyFast(memberId, propertyName, defaultValueGenerator, baseValueAccessor);
-	}
-
-	/// <summary>
-	///     Singleton-aware overload of
-	///     <see cref="GetPropertyFast{TResult}(int, string, Func{MockBehavior, TResult}, Func{TResult}?)" />
+	///     Allocation-free fast-path overload of <see cref="GetProperty{TResult}(string, Func{TResult}, Func{TResult}?)" />
 	///     that records the shared <paramref name="access" /> singleton emitted by the source generator,
 	///     avoiding the per-call <see cref="PropertyGetterAccess" /> allocation. The
 	///     <see cref="FastPropertyGetterBuffer" /> stores only a sequence number per call and emits the
 	///     same singleton for every recorded record on verification; the cold-path fall-through likewise
 	///     registers the singleton.
 	/// </summary>
+	/// <remarks>
+	///     Avoids the per-call closure allocation by accepting a static <see cref="Func{T, TResult}" /> that takes
+	///     the active <see cref="MockBehavior" /> as its argument — the source generator emits a <c>static</c>
+	///     lambda so the C# compiler caches the delegate in a static field.
+	/// </remarks>
 	/// <typeparam name="TResult">The property's value type.</typeparam>
 	/// <param name="memberId">The generator-emitted member id for the property getter.</param>
 	/// <param name="access">The shared <see cref="PropertyGetterAccess" /> singleton for the property.</param>
@@ -684,33 +664,14 @@ private TResult ResolvePropertyFast<TResult>(int memberId, string propertyName,
 		return ResolveGetterInternal(propertyName, bridge, baseValueAccessor, null);
 	}
 
-	private void RecordPropertyGetter(int memberId, string propertyName)
-	{
-		if (Interactions is FastMockInteractions fast)
-		{
-			IFastMemberBuffer?[] buffers = fast.Buffers;
-			if ((uint)memberId < (uint)buffers.Length &&
-			    buffers[memberId] is FastPropertyGetterBuffer buffer)
-			{
-				buffer.Append(propertyName);
-				return;
-			}
-		}
-
-		Interactions.RegisterInteraction(new PropertyGetterAccess(propertyName));
-	}
-
 	private void RecordPropertyGetter(int memberId, PropertyGetterAccess access)
 	{
-		if (Interactions is FastMockInteractions fast)
+		if (Interactions is FastMockInteractions fast && (uint)memberId < (uint)fast.Buffers.Length)
 		{
-			IFastMemberBuffer?[] buffers = fast.Buffers;
-			if ((uint)memberId < (uint)buffers.Length &&
-			    buffers[memberId] is FastPropertyGetterBuffer buffer)
-			{
-				buffer.Append();
-				return;
-			}
+			FastPropertyGetterBuffer buffer = fast.GetOrCreateBuffer(
+				memberId, static (f, a) => new FastPropertyGetterBuffer(f, a), access);
+			buffer.Append();
+			return;
 		}
 
 		Interactions.RegisterInteraction(access);
@@ -853,15 +814,12 @@ public bool SetPropertyFast<T>(int memberId, int setterMemberId, string property
 
 	private void RecordPropertySetter<T>(int memberId, string propertyName, T value)
 	{
-		if (Interactions is FastMockInteractions fast)
+		if (Interactions is FastMockInteractions fast && (uint)memberId < (uint)fast.Buffers.Length)
 		{
-			IFastMemberBuffer?[] buffers = fast.Buffers;
-			if ((uint)memberId < (uint)buffers.Length &&
-			    buffers[memberId] is FastPropertySetterBuffer<T> buffer)
-			{
-				buffer.Append(propertyName, value);
-				return;
-			}
+			FastPropertySetterBuffer<T> buffer = fast.GetOrCreateBuffer(
+				memberId, static f => new FastPropertySetterBuffer<T>(f));
+			buffer.Append(propertyName, value);
+			return;
 		}
 
 		Interactions.RegisterInteraction(new PropertySetterAccess<T>(propertyName, value));
@@ -1075,15 +1033,15 @@ public void RemoveEvent(int memberId, string name, object? target, MethodInfo? m
 
 	private void RecordEvent(int memberId, string name, object? target, MethodInfo method, bool isSubscribe)
 	{
-		if (Interactions is FastMockInteractions fast)
-		{
-			IFastMemberBuffer?[] buffers = fast.Buffers;
-			if ((uint)memberId < (uint)buffers.Length &&
-			    buffers[memberId] is FastEventBuffer buffer)
-			{
-				buffer.Append(name, target, method);
-				return;
-			}
+		if (Interactions is FastMockInteractions fast && (uint)memberId < (uint)fast.Buffers.Length)
+		{
+			FastEventBuffer buffer = isSubscribe
+				? fast.GetOrCreateBuffer(memberId,
+					static f => new FastEventBuffer(f, FastEventBufferKind.Subscribe))
+				: fast.GetOrCreateBuffer(memberId,
+					static f => new FastEventBuffer(f, FastEventBufferKind.Unsubscribe));
+			buffer.Append(name, target, method);
+			return;
 		}
 
 		if (isSubscribe)
diff --git a/Tests/Mockolate.Api.Tests/Expected/Mockolate_net10.0.txt b/Tests/Mockolate.Api.Tests/Expected/Mockolate_net10.0.txt
index f88e7262..3c90f6e0 100644
--- a/Tests/Mockolate.Api.Tests/Expected/Mockolate_net10.0.txt
+++ b/Tests/Mockolate.Api.Tests/Expected/Mockolate_net10.0.txt
@@ -222,7 +222,6 @@ namespace Mockolate
         public TResult GetProperty<TResult>(Mockolate.Interactions.PropertyGetterAccess access, System.Func<TResult> defaultValueGenerator, System.Func<TResult>? baseValueAccessor) { }
         public TResult GetProperty<TResult>(string propertyName, System.Func<TResult> defaultValueGenerator, System.Func<TResult>? baseValueAccessor) { }
         public TResult GetPropertyFast<TResult>(int memberId, Mockolate.Interactions.PropertyGetterAccess access, System.Func<Mockolate.MockBehavior, TResult> defaultValueGenerator, System.Func<TResult>? baseValueAccessor = null) { }
-        public TResult GetPropertyFast<TResult>(int memberId, string propertyName, System.Func<Mockolate.MockBehavior, TResult> defaultValueGenerator, System.Func<TResult>? baseValueAccessor = null) { }
         public System.Collections.Generic.IReadOnlyCollection<Mockolate.Setup.ISetup> GetUnusedSetups(Mockolate.Interactions.IMockInteractions interactions) { }
         public Mockolate.Verify.VerificationResult<T> IndexerGot<T>(T subject, int memberId, System.Func<Mockolate.Interactions.IInteraction, bool> gotPredicate, System.Func<string> parametersDescription) { }
         public Mockolate.Verify.VerificationResult<T> IndexerGotTyped<T, T1>(T subject, int memberId, Mockolate.Parameters.IParameterMatch<T1> match1, System.Func<string> parametersDescription) { }
@@ -653,35 +652,21 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} event {_kind}s")]
     public sealed class FastEventBuffer : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastEventBuffer(Mockolate.Interactions.FastMockInteractions owner, Mockolate.Interactions.FastEventBufferKind kind) { }
         public int Count { get; }
         public void Append(string name, object? target, System.Reflection.MethodInfo method) { }
         public void Clear() { }
         public int ConsumeMatching() { }
     }
-    public static class FastEventBufferFactory
-    {
-        public static Mockolate.Interactions.FastEventBuffer InstallEventSubscribe(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastEventBuffer InstallEventUnsubscribe(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-    }
     public enum FastEventBufferKind
     {
         Subscribe = 0,
         Unsubscribe = 1,
     }
-    public static class FastIndexerBufferFactory
-    {
-        public static Mockolate.Interactions.FastIndexerGetterBuffer<T1> InstallIndexerGetter<T1>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastIndexerGetterBuffer<T1, T2> InstallIndexerGetter<T1, T2>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastIndexerGetterBuffer<T1, T2, T3> InstallIndexerGetter<T1, T2, T3>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastIndexerGetterBuffer<T1, T2, T3, T4> InstallIndexerGetter<T1, T2, T3, T4>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastIndexerSetterBuffer<T1, TValue> InstallIndexerSetter<T1, TValue>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastIndexerSetterBuffer<T1, T2, TValue> InstallIndexerSetter<T1, T2, TValue>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastIndexerSetterBuffer<T1, T2, T3, TValue> InstallIndexerSetter<T1, T2, T3, TValue>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastIndexerSetterBuffer<T1, T2, T3, T4, TValue> InstallIndexerSetter<T1, T2, T3, T4, TValue>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-    }
     [System.Diagnostics.DebuggerDisplay("{Count} indexer gets")]
     public sealed class FastIndexerGetterBuffer<T1> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastIndexerGetterBuffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(Mockolate.Interactions.IndexerGetterAccess<T1> access) { }
         public void Append(T1 parameter1) { }
@@ -691,6 +676,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} indexer gets")]
     public sealed class FastIndexerGetterBuffer<T1, T2> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastIndexerGetterBuffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(Mockolate.Interactions.IndexerGetterAccess<T1, T2> access) { }
         public void Append(T1 parameter1, T2 parameter2) { }
@@ -700,6 +686,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} indexer gets")]
     public sealed class FastIndexerGetterBuffer<T1, T2, T3> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastIndexerGetterBuffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(Mockolate.Interactions.IndexerGetterAccess<T1, T2, T3> access) { }
         public void Append(T1 parameter1, T2 parameter2, T3 parameter3) { }
@@ -709,6 +696,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} indexer gets")]
     public sealed class FastIndexerGetterBuffer<T1, T2, T3, T4> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastIndexerGetterBuffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(Mockolate.Interactions.IndexerGetterAccess<T1, T2, T3, T4> access) { }
         public void Append(T1 parameter1, T2 parameter2, T3 parameter3, T4 parameter4) { }
@@ -718,6 +706,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} indexer sets")]
     public sealed class FastIndexerSetterBuffer<T1, TValue> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastIndexerSetterBuffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(Mockolate.Interactions.IndexerSetterAccess<T1, TValue> access) { }
         public void Append(T1 parameter1, TValue value) { }
@@ -727,6 +716,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} indexer sets")]
     public sealed class FastIndexerSetterBuffer<T1, T2, TValue> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastIndexerSetterBuffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(Mockolate.Interactions.IndexerSetterAccess<T1, T2, TValue> access) { }
         public void Append(T1 parameter1, T2 parameter2, TValue value) { }
@@ -736,6 +726,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} indexer sets")]
     public sealed class FastIndexerSetterBuffer<T1, T2, T3, TValue> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastIndexerSetterBuffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(Mockolate.Interactions.IndexerSetterAccess<T1, T2, T3, TValue> access) { }
         public void Append(T1 parameter1, T2 parameter2, T3 parameter3, TValue value) { }
@@ -745,6 +736,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} indexer sets")]
     public sealed class FastIndexerSetterBuffer<T1, T2, T3, T4, TValue> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastIndexerSetterBuffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(Mockolate.Interactions.IndexerSetterAccess<T1, T2, T3, T4, TValue> access) { }
         public void Append(T1 parameter1, T2 parameter2, T3 parameter3, T4 parameter4, TValue value) { }
@@ -754,6 +746,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} method calls")]
     public sealed class FastMethod0Buffer : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastMethod0Buffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(string name) { }
         public void Clear() { }
@@ -762,6 +755,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} method calls")]
     public sealed class FastMethod1Buffer<T1> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastMethod1Buffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(string name, T1 parameter1) { }
         public void Clear() { }
@@ -770,6 +764,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} method calls")]
     public sealed class FastMethod2Buffer<T1, T2> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastMethod2Buffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(string name, T1 parameter1, T2 parameter2) { }
         public void Clear() { }
@@ -778,6 +773,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} method calls")]
     public sealed class FastMethod3Buffer<T1, T2, T3> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastMethod3Buffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(string name, T1 parameter1, T2 parameter2, T3 parameter3) { }
         public void Clear() { }
@@ -786,19 +782,12 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} method calls")]
     public sealed class FastMethod4Buffer<T1, T2, T3, T4> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastMethod4Buffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(string name, T1 parameter1, T2 parameter2, T3 parameter3, T4 parameter4) { }
         public void Clear() { }
         public int ConsumeMatching(Mockolate.Parameters.IParameterMatch<T1> match1, Mockolate.Parameters.IParameterMatch<T2> match2, Mockolate.Parameters.IParameterMatch<T3> match3, Mockolate.Parameters.IParameterMatch<T4> match4) { }
     }
-    public static class FastMethodBufferFactory
-    {
-        public static Mockolate.Interactions.FastMethod0Buffer InstallMethod(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastMethod1Buffer<T1> InstallMethod<T1>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastMethod2Buffer<T1, T2> InstallMethod<T1, T2>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastMethod3Buffer<T1, T2, T3> InstallMethod<T1, T2, T3>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastMethod4Buffer<T1, T2, T3, T4> InstallMethod<T1, T2, T3, T4>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-    }
     [System.Diagnostics.DebuggerDisplay("{Count} interactions")]
     public class FastMockInteractions : Mockolate.Interactions.IMockInteractions, System.Collections.Generic.IEnumerable<Mockolate.Interactions.IInteraction>, System.Collections.Generic.IReadOnlyCollection<Mockolate.Interactions.IInteraction>, System.Collections.IEnumerable
     {
@@ -811,29 +800,27 @@ namespace Mockolate.Interactions
         public event System.EventHandler? OnClearing;
         public void Clear() { }
         public System.Collections.Generic.IEnumerator<Mockolate.Interactions.IInteraction> GetEnumerator() { }
+        public TBuffer GetOrCreateBuffer<TBuffer>(int memberId, System.Func<Mockolate.Interactions.FastMockInteractions, TBuffer> factory)
+            where TBuffer :  class, Mockolate.Interactions.IFastMemberBuffer { }
+        public TBuffer GetOrCreateBuffer<TBuffer, TState>(int memberId, System.Func<Mockolate.Interactions.FastMockInteractions, TState, TBuffer> factory, TState state)
+            where TBuffer :  class, Mockolate.Interactions.IFastMemberBuffer { }
         public System.Collections.Generic.IReadOnlyCollection<Mockolate.Interactions.IInteraction> GetUnverifiedInteractions() { }
-        public void InstallBuffer(int memberId, Mockolate.Interactions.IFastMemberBuffer buffer) { }
         public long NextSequence() { }
         public void RaiseAdded() { }
     }
-    public static class FastPropertyBufferFactory
-    {
-        public static Mockolate.Interactions.FastPropertyGetterBuffer InstallPropertyGetter(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastPropertyGetterBuffer InstallPropertyGetter(this Mockolate.Interactions.FastMockInteractions interactions, int memberId, Mockolate.Interactions.PropertyGetterAccess access) { }
-        public static Mockolate.Interactions.FastPropertySetterBuffer<T> InstallPropertySetter<T>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-    }
     [System.Diagnostics.DebuggerDisplay("{Count} property gets")]
     public sealed class FastPropertyGetterBuffer : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastPropertyGetterBuffer(Mockolate.Interactions.FastMockInteractions owner, Mockolate.Interactions.PropertyGetterAccess access) { }
         public int Count { get; }
         public void Append() { }
-        public void Append(string name) { }
         public void Clear() { }
         public int ConsumeMatching() { }
     }
     [System.Diagnostics.DebuggerDisplay("{Count} property sets")]
     public sealed class FastPropertySetterBuffer<T> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastPropertySetterBuffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(string name, T value) { }
         public void Clear() { }
diff --git a/Tests/Mockolate.Api.Tests/Expected/Mockolate_net8.0.txt b/Tests/Mockolate.Api.Tests/Expected/Mockolate_net8.0.txt
index f577d8d7..6337ffb5 100644
--- a/Tests/Mockolate.Api.Tests/Expected/Mockolate_net8.0.txt
+++ b/Tests/Mockolate.Api.Tests/Expected/Mockolate_net8.0.txt
@@ -215,7 +215,6 @@ namespace Mockolate
         public TResult GetProperty<TResult>(Mockolate.Interactions.PropertyGetterAccess access, System.Func<TResult> defaultValueGenerator, System.Func<TResult>? baseValueAccessor) { }
         public TResult GetProperty<TResult>(string propertyName, System.Func<TResult> defaultValueGenerator, System.Func<TResult>? baseValueAccessor) { }
         public TResult GetPropertyFast<TResult>(int memberId, Mockolate.Interactions.PropertyGetterAccess access, System.Func<Mockolate.MockBehavior, TResult> defaultValueGenerator, System.Func<TResult>? baseValueAccessor = null) { }
-        public TResult GetPropertyFast<TResult>(int memberId, string propertyName, System.Func<Mockolate.MockBehavior, TResult> defaultValueGenerator, System.Func<TResult>? baseValueAccessor = null) { }
         public System.Collections.Generic.IReadOnlyCollection<Mockolate.Setup.ISetup> GetUnusedSetups(Mockolate.Interactions.IMockInteractions interactions) { }
         public Mockolate.Verify.VerificationResult<T> IndexerGot<T>(T subject, int memberId, System.Func<Mockolate.Interactions.IInteraction, bool> gotPredicate, System.Func<string> parametersDescription) { }
         public Mockolate.Verify.VerificationResult<T> IndexerGotTyped<T, T1>(T subject, int memberId, Mockolate.Parameters.IParameterMatch<T1> match1, System.Func<string> parametersDescription) { }
@@ -644,35 +643,21 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} event {_kind}s")]
     public sealed class FastEventBuffer : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastEventBuffer(Mockolate.Interactions.FastMockInteractions owner, Mockolate.Interactions.FastEventBufferKind kind) { }
         public int Count { get; }
         public void Append(string name, object? target, System.Reflection.MethodInfo method) { }
         public void Clear() { }
         public int ConsumeMatching() { }
     }
-    public static class FastEventBufferFactory
-    {
-        public static Mockolate.Interactions.FastEventBuffer InstallEventSubscribe(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastEventBuffer InstallEventUnsubscribe(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-    }
     public enum FastEventBufferKind
     {
         Subscribe = 0,
         Unsubscribe = 1,
     }
-    public static class FastIndexerBufferFactory
-    {
-        public static Mockolate.Interactions.FastIndexerGetterBuffer<T1> InstallIndexerGetter<T1>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastIndexerGetterBuffer<T1, T2> InstallIndexerGetter<T1, T2>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastIndexerGetterBuffer<T1, T2, T3> InstallIndexerGetter<T1, T2, T3>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastIndexerGetterBuffer<T1, T2, T3, T4> InstallIndexerGetter<T1, T2, T3, T4>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastIndexerSetterBuffer<T1, TValue> InstallIndexerSetter<T1, TValue>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastIndexerSetterBuffer<T1, T2, TValue> InstallIndexerSetter<T1, T2, TValue>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastIndexerSetterBuffer<T1, T2, T3, TValue> InstallIndexerSetter<T1, T2, T3, TValue>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastIndexerSetterBuffer<T1, T2, T3, T4, TValue> InstallIndexerSetter<T1, T2, T3, T4, TValue>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-    }
     [System.Diagnostics.DebuggerDisplay("{Count} indexer gets")]
     public sealed class FastIndexerGetterBuffer<T1> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastIndexerGetterBuffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(Mockolate.Interactions.IndexerGetterAccess<T1> access) { }
         public void Append(T1 parameter1) { }
@@ -682,6 +667,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} indexer gets")]
     public sealed class FastIndexerGetterBuffer<T1, T2> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastIndexerGetterBuffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(Mockolate.Interactions.IndexerGetterAccess<T1, T2> access) { }
         public void Append(T1 parameter1, T2 parameter2) { }
@@ -691,6 +677,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} indexer gets")]
     public sealed class FastIndexerGetterBuffer<T1, T2, T3> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastIndexerGetterBuffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(Mockolate.Interactions.IndexerGetterAccess<T1, T2, T3> access) { }
         public void Append(T1 parameter1, T2 parameter2, T3 parameter3) { }
@@ -700,6 +687,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} indexer gets")]
     public sealed class FastIndexerGetterBuffer<T1, T2, T3, T4> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastIndexerGetterBuffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(Mockolate.Interactions.IndexerGetterAccess<T1, T2, T3, T4> access) { }
         public void Append(T1 parameter1, T2 parameter2, T3 parameter3, T4 parameter4) { }
@@ -709,6 +697,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} indexer sets")]
     public sealed class FastIndexerSetterBuffer<T1, TValue> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastIndexerSetterBuffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(Mockolate.Interactions.IndexerSetterAccess<T1, TValue> access) { }
         public void Append(T1 parameter1, TValue value) { }
@@ -718,6 +707,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} indexer sets")]
     public sealed class FastIndexerSetterBuffer<T1, T2, TValue> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastIndexerSetterBuffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(Mockolate.Interactions.IndexerSetterAccess<T1, T2, TValue> access) { }
         public void Append(T1 parameter1, T2 parameter2, TValue value) { }
@@ -727,6 +717,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} indexer sets")]
     public sealed class FastIndexerSetterBuffer<T1, T2, T3, TValue> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastIndexerSetterBuffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(Mockolate.Interactions.IndexerSetterAccess<T1, T2, T3, TValue> access) { }
         public void Append(T1 parameter1, T2 parameter2, T3 parameter3, TValue value) { }
@@ -736,6 +727,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} indexer sets")]
     public sealed class FastIndexerSetterBuffer<T1, T2, T3, T4, TValue> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastIndexerSetterBuffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(Mockolate.Interactions.IndexerSetterAccess<T1, T2, T3, T4, TValue> access) { }
         public void Append(T1 parameter1, T2 parameter2, T3 parameter3, T4 parameter4, TValue value) { }
@@ -745,6 +737,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} method calls")]
     public sealed class FastMethod0Buffer : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastMethod0Buffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(string name) { }
         public void Clear() { }
@@ -753,6 +746,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} method calls")]
     public sealed class FastMethod1Buffer<T1> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastMethod1Buffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(string name, T1 parameter1) { }
         public void Clear() { }
@@ -761,6 +755,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} method calls")]
     public sealed class FastMethod2Buffer<T1, T2> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastMethod2Buffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(string name, T1 parameter1, T2 parameter2) { }
         public void Clear() { }
@@ -769,6 +764,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} method calls")]
     public sealed class FastMethod3Buffer<T1, T2, T3> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastMethod3Buffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(string name, T1 parameter1, T2 parameter2, T3 parameter3) { }
         public void Clear() { }
@@ -777,19 +773,12 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} method calls")]
     public sealed class FastMethod4Buffer<T1, T2, T3, T4> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastMethod4Buffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(string name, T1 parameter1, T2 parameter2, T3 parameter3, T4 parameter4) { }
         public void Clear() { }
         public int ConsumeMatching(Mockolate.Parameters.IParameterMatch<T1> match1, Mockolate.Parameters.IParameterMatch<T2> match2, Mockolate.Parameters.IParameterMatch<T3> match3, Mockolate.Parameters.IParameterMatch<T4> match4) { }
     }
-    public static class FastMethodBufferFactory
-    {
-        public static Mockolate.Interactions.FastMethod0Buffer InstallMethod(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastMethod1Buffer<T1> InstallMethod<T1>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastMethod2Buffer<T1, T2> InstallMethod<T1, T2>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastMethod3Buffer<T1, T2, T3> InstallMethod<T1, T2, T3>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastMethod4Buffer<T1, T2, T3, T4> InstallMethod<T1, T2, T3, T4>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-    }
     [System.Diagnostics.DebuggerDisplay("{Count} interactions")]
     public class FastMockInteractions : Mockolate.Interactions.IMockInteractions, System.Collections.Generic.IEnumerable<Mockolate.Interactions.IInteraction>, System.Collections.Generic.IReadOnlyCollection<Mockolate.Interactions.IInteraction>, System.Collections.IEnumerable
     {
@@ -802,29 +791,27 @@ namespace Mockolate.Interactions
         public event System.EventHandler? OnClearing;
         public void Clear() { }
         public System.Collections.Generic.IEnumerator<Mockolate.Interactions.IInteraction> GetEnumerator() { }
+        public TBuffer GetOrCreateBuffer<TBuffer>(int memberId, System.Func<Mockolate.Interactions.FastMockInteractions, TBuffer> factory)
+            where TBuffer :  class, Mockolate.Interactions.IFastMemberBuffer { }
+        public TBuffer GetOrCreateBuffer<TBuffer, TState>(int memberId, System.Func<Mockolate.Interactions.FastMockInteractions, TState, TBuffer> factory, TState state)
+            where TBuffer :  class, Mockolate.Interactions.IFastMemberBuffer { }
         public System.Collections.Generic.IReadOnlyCollection<Mockolate.Interactions.IInteraction> GetUnverifiedInteractions() { }
-        public void InstallBuffer(int memberId, Mockolate.Interactions.IFastMemberBuffer buffer) { }
         public long NextSequence() { }
         public void RaiseAdded() { }
     }
-    public static class FastPropertyBufferFactory
-    {
-        public static Mockolate.Interactions.FastPropertyGetterBuffer InstallPropertyGetter(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastPropertyGetterBuffer InstallPropertyGetter(this Mockolate.Interactions.FastMockInteractions interactions, int memberId, Mockolate.Interactions.PropertyGetterAccess access) { }
-        public static Mockolate.Interactions.FastPropertySetterBuffer<T> InstallPropertySetter<T>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-    }
     [System.Diagnostics.DebuggerDisplay("{Count} property gets")]
     public sealed class FastPropertyGetterBuffer : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastPropertyGetterBuffer(Mockolate.Interactions.FastMockInteractions owner, Mockolate.Interactions.PropertyGetterAccess access) { }
         public int Count { get; }
         public void Append() { }
-        public void Append(string name) { }
         public void Clear() { }
         public int ConsumeMatching() { }
     }
     [System.Diagnostics.DebuggerDisplay("{Count} property sets")]
     public sealed class FastPropertySetterBuffer<T> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastPropertySetterBuffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(string name, T value) { }
         public void Clear() { }
diff --git a/Tests/Mockolate.Api.Tests/Expected/Mockolate_netstandard2.0.txt b/Tests/Mockolate.Api.Tests/Expected/Mockolate_netstandard2.0.txt
index 6fbc0518..5e4e3a1a 100644
--- a/Tests/Mockolate.Api.Tests/Expected/Mockolate_netstandard2.0.txt
+++ b/Tests/Mockolate.Api.Tests/Expected/Mockolate_netstandard2.0.txt
@@ -202,7 +202,6 @@ namespace Mockolate
         public TResult GetProperty<TResult>(Mockolate.Interactions.PropertyGetterAccess access, System.Func<TResult> defaultValueGenerator, System.Func<TResult>? baseValueAccessor) { }
         public TResult GetProperty<TResult>(string propertyName, System.Func<TResult> defaultValueGenerator, System.Func<TResult>? baseValueAccessor) { }
         public TResult GetPropertyFast<TResult>(int memberId, Mockolate.Interactions.PropertyGetterAccess access, System.Func<Mockolate.MockBehavior, TResult> defaultValueGenerator, System.Func<TResult>? baseValueAccessor = null) { }
-        public TResult GetPropertyFast<TResult>(int memberId, string propertyName, System.Func<Mockolate.MockBehavior, TResult> defaultValueGenerator, System.Func<TResult>? baseValueAccessor = null) { }
         public System.Collections.Generic.IReadOnlyCollection<Mockolate.Setup.ISetup> GetUnusedSetups(Mockolate.Interactions.IMockInteractions interactions) { }
         public Mockolate.Verify.VerificationResult<T> IndexerGot<T>(T subject, int memberId, System.Func<Mockolate.Interactions.IInteraction, bool> gotPredicate, System.Func<string> parametersDescription) { }
         public Mockolate.Verify.VerificationResult<T> IndexerGotTyped<T, T1>(T subject, int memberId, Mockolate.Parameters.IParameterMatch<T1> match1, System.Func<string> parametersDescription) { }
@@ -603,35 +602,21 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} event {_kind}s")]
     public sealed class FastEventBuffer : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastEventBuffer(Mockolate.Interactions.FastMockInteractions owner, Mockolate.Interactions.FastEventBufferKind kind) { }
         public int Count { get; }
         public void Append(string name, object? target, System.Reflection.MethodInfo method) { }
         public void Clear() { }
         public int ConsumeMatching() { }
     }
-    public static class FastEventBufferFactory
-    {
-        public static Mockolate.Interactions.FastEventBuffer InstallEventSubscribe(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastEventBuffer InstallEventUnsubscribe(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-    }
     public enum FastEventBufferKind
     {
         Subscribe = 0,
         Unsubscribe = 1,
     }
-    public static class FastIndexerBufferFactory
-    {
-        public static Mockolate.Interactions.FastIndexerGetterBuffer<T1> InstallIndexerGetter<T1>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastIndexerGetterBuffer<T1, T2> InstallIndexerGetter<T1, T2>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastIndexerGetterBuffer<T1, T2, T3> InstallIndexerGetter<T1, T2, T3>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastIndexerGetterBuffer<T1, T2, T3, T4> InstallIndexerGetter<T1, T2, T3, T4>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastIndexerSetterBuffer<T1, TValue> InstallIndexerSetter<T1, TValue>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastIndexerSetterBuffer<T1, T2, TValue> InstallIndexerSetter<T1, T2, TValue>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastIndexerSetterBuffer<T1, T2, T3, TValue> InstallIndexerSetter<T1, T2, T3, TValue>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastIndexerSetterBuffer<T1, T2, T3, T4, TValue> InstallIndexerSetter<T1, T2, T3, T4, TValue>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-    }
     [System.Diagnostics.DebuggerDisplay("{Count} indexer gets")]
     public sealed class FastIndexerGetterBuffer<T1> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastIndexerGetterBuffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(Mockolate.Interactions.IndexerGetterAccess<T1> access) { }
         public void Append(T1 parameter1) { }
@@ -641,6 +626,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} indexer gets")]
     public sealed class FastIndexerGetterBuffer<T1, T2> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastIndexerGetterBuffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(Mockolate.Interactions.IndexerGetterAccess<T1, T2> access) { }
         public void Append(T1 parameter1, T2 parameter2) { }
@@ -650,6 +636,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} indexer gets")]
     public sealed class FastIndexerGetterBuffer<T1, T2, T3> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastIndexerGetterBuffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(Mockolate.Interactions.IndexerGetterAccess<T1, T2, T3> access) { }
         public void Append(T1 parameter1, T2 parameter2, T3 parameter3) { }
@@ -659,6 +646,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} indexer gets")]
     public sealed class FastIndexerGetterBuffer<T1, T2, T3, T4> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastIndexerGetterBuffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(Mockolate.Interactions.IndexerGetterAccess<T1, T2, T3, T4> access) { }
         public void Append(T1 parameter1, T2 parameter2, T3 parameter3, T4 parameter4) { }
@@ -668,6 +656,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} indexer sets")]
     public sealed class FastIndexerSetterBuffer<T1, TValue> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastIndexerSetterBuffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(Mockolate.Interactions.IndexerSetterAccess<T1, TValue> access) { }
         public void Append(T1 parameter1, TValue value) { }
@@ -677,6 +666,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} indexer sets")]
     public sealed class FastIndexerSetterBuffer<T1, T2, TValue> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastIndexerSetterBuffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(Mockolate.Interactions.IndexerSetterAccess<T1, T2, TValue> access) { }
         public void Append(T1 parameter1, T2 parameter2, TValue value) { }
@@ -686,6 +676,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} indexer sets")]
     public sealed class FastIndexerSetterBuffer<T1, T2, T3, TValue> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastIndexerSetterBuffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(Mockolate.Interactions.IndexerSetterAccess<T1, T2, T3, TValue> access) { }
         public void Append(T1 parameter1, T2 parameter2, T3 parameter3, TValue value) { }
@@ -695,6 +686,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} indexer sets")]
     public sealed class FastIndexerSetterBuffer<T1, T2, T3, T4, TValue> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastIndexerSetterBuffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(Mockolate.Interactions.IndexerSetterAccess<T1, T2, T3, T4, TValue> access) { }
         public void Append(T1 parameter1, T2 parameter2, T3 parameter3, T4 parameter4, TValue value) { }
@@ -704,6 +696,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} method calls")]
     public sealed class FastMethod0Buffer : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastMethod0Buffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(string name) { }
         public void Clear() { }
@@ -712,6 +705,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} method calls")]
     public sealed class FastMethod1Buffer<T1> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastMethod1Buffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(string name, T1 parameter1) { }
         public void Clear() { }
@@ -720,6 +714,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} method calls")]
     public sealed class FastMethod2Buffer<T1, T2> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastMethod2Buffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(string name, T1 parameter1, T2 parameter2) { }
         public void Clear() { }
@@ -728,6 +723,7 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} method calls")]
     public sealed class FastMethod3Buffer<T1, T2, T3> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastMethod3Buffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(string name, T1 parameter1, T2 parameter2, T3 parameter3) { }
         public void Clear() { }
@@ -736,19 +732,12 @@ namespace Mockolate.Interactions
     [System.Diagnostics.DebuggerDisplay("{Count} method calls")]
     public sealed class FastMethod4Buffer<T1, T2, T3, T4> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastMethod4Buffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(string name, T1 parameter1, T2 parameter2, T3 parameter3, T4 parameter4) { }
         public void Clear() { }
         public int ConsumeMatching(Mockolate.Parameters.IParameterMatch<T1> match1, Mockolate.Parameters.IParameterMatch<T2> match2, Mockolate.Parameters.IParameterMatch<T3> match3, Mockolate.Parameters.IParameterMatch<T4> match4) { }
     }
-    public static class FastMethodBufferFactory
-    {
-        public static Mockolate.Interactions.FastMethod0Buffer InstallMethod(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastMethod1Buffer<T1> InstallMethod<T1>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastMethod2Buffer<T1, T2> InstallMethod<T1, T2>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastMethod3Buffer<T1, T2, T3> InstallMethod<T1, T2, T3>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastMethod4Buffer<T1, T2, T3, T4> InstallMethod<T1, T2, T3, T4>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-    }
     [System.Diagnostics.DebuggerDisplay("{Count} interactions")]
     public class FastMockInteractions : Mockolate.Interactions.IMockInteractions, System.Collections.Generic.IEnumerable<Mockolate.Interactions.IInteraction>, System.Collections.Generic.IReadOnlyCollection<Mockolate.Interactions.IInteraction>, System.Collections.IEnumerable
     {
@@ -761,29 +750,27 @@ namespace Mockolate.Interactions
         public event System.EventHandler? OnClearing;
         public void Clear() { }
         public System.Collections.Generic.IEnumerator<Mockolate.Interactions.IInteraction> GetEnumerator() { }
+        public TBuffer GetOrCreateBuffer<TBuffer>(int memberId, System.Func<Mockolate.Interactions.FastMockInteractions, TBuffer> factory)
+            where TBuffer :  class, Mockolate.Interactions.IFastMemberBuffer { }
+        public TBuffer GetOrCreateBuffer<TBuffer, TState>(int memberId, System.Func<Mockolate.Interactions.FastMockInteractions, TState, TBuffer> factory, TState state)
+            where TBuffer :  class, Mockolate.Interactions.IFastMemberBuffer { }
         public System.Collections.Generic.IReadOnlyCollection<Mockolate.Interactions.IInteraction> GetUnverifiedInteractions() { }
-        public void InstallBuffer(int memberId, Mockolate.Interactions.IFastMemberBuffer buffer) { }
         public long NextSequence() { }
         public void RaiseAdded() { }
     }
-    public static class FastPropertyBufferFactory
-    {
-        public static Mockolate.Interactions.FastPropertyGetterBuffer InstallPropertyGetter(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-        public static Mockolate.Interactions.FastPropertyGetterBuffer InstallPropertyGetter(this Mockolate.Interactions.FastMockInteractions interactions, int memberId, Mockolate.Interactions.PropertyGetterAccess access) { }
-        public static Mockolate.Interactions.FastPropertySetterBuffer<T> InstallPropertySetter<T>(this Mockolate.Interactions.FastMockInteractions interactions, int memberId) { }
-    }
     [System.Diagnostics.DebuggerDisplay("{Count} property gets")]
     public sealed class FastPropertyGetterBuffer : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastPropertyGetterBuffer(Mockolate.Interactions.FastMockInteractions owner, Mockolate.Interactions.PropertyGetterAccess access) { }
         public int Count { get; }
         public void Append() { }
-        public void Append(string name) { }
         public void Clear() { }
         public int ConsumeMatching() { }
     }
     [System.Diagnostics.DebuggerDisplay("{Count} property sets")]
     public sealed class FastPropertySetterBuffer<T> : Mockolate.Interactions.IFastMemberBuffer
     {
+        public FastPropertySetterBuffer(Mockolate.Interactions.FastMockInteractions owner) { }
         public int Count { get; }
         public void Append(string name, T value) { }
         public void Clear() { }
diff --git a/Tests/Mockolate.Internal.Tests/Interactions/ChunkedSlotStorageTests.cs b/Tests/Mockolate.Internal.Tests/Interactions/ChunkedSlotStorageTests.cs
index 6caec1e8..c37e02dc 100644
--- a/Tests/Mockolate.Internal.Tests/Interactions/ChunkedSlotStorageTests.cs
+++ b/Tests/Mockolate.Internal.Tests/Interactions/ChunkedSlotStorageTests.cs
@@ -11,7 +11,8 @@ public async Task Clear_AfterMultipleChunks_ResetsCountAndAllowsRefill()
 	{
 		const int total = (ChunkedSlotStorage<int>.ChunkSize * 2) + 5;
 		FastMockInteractions store = new(1);
-		FastMethod1Buffer<int> buffer = store.InstallMethod<int>(0);
+		FastMethod1Buffer<int> buffer = store.GetOrCreateBuffer<FastMethod1Buffer<int>>(0,
+			static f => new FastMethod1Buffer<int>(f));
 
 		for (int i = 0; i < total; i++)
 		{
@@ -32,7 +33,8 @@ public async Task SlotForWrite_AcrossMultipleChunks_PreservesAllRecords()
 	{
 		const int total = ChunkedSlotStorage<int>.ChunkSize * 3;
 		FastMockInteractions store = new(1);
-		FastMethod1Buffer<int> buffer = store.InstallMethod<int>(0);
+		FastMethod1Buffer<int> buffer = store.GetOrCreateBuffer<FastMethod1Buffer<int>>(0,
+			static f => new FastMethod1Buffer<int>(f));
 
 		for (int i = 0; i < total; i++)
 		{
@@ -53,7 +55,8 @@ public async Task SlotForWrite_BeyondInitialChunksArrayLength_ExpandsArrayUnderL
 	{
 		const int total = (ChunkedSlotStorage<int>.ChunkSize * 4) + 1;
 		FastMockInteractions store = new(1);
-		FastMethod1Buffer<int> buffer = store.InstallMethod<int>(0);
+		FastMethod1Buffer<int> buffer = store.GetOrCreateBuffer<FastMethod1Buffer<int>>(0,
+			static f => new FastMethod1Buffer<int>(f));
 
 		for (int i = 0; i < total; i++)
 		{
diff --git a/Tests/Mockolate.Internal.Tests/Interactions/FastBufferBoxingAndUnverifiedTests.cs b/Tests/Mockolate.Internal.Tests/Interactions/FastBufferBoxingAndUnverifiedTests.cs
index 90a9b383..f82ea779 100644
--- a/Tests/Mockolate.Internal.Tests/Interactions/FastBufferBoxingAndUnverifiedTests.cs
+++ b/Tests/Mockolate.Internal.Tests/Interactions/FastBufferBoxingAndUnverifiedTests.cs
@@ -13,8 +13,8 @@ public async Task FastEventBuffer_AppendBoxed_KindMatters()
 	{
 		FastMockInteractions subscribeStore = new(1);
 		FastMockInteractions unsubscribeStore = new(1);
-		FastEventBuffer subscribe = subscribeStore.InstallEventSubscribe(0);
-		FastEventBuffer unsubscribe = unsubscribeStore.InstallEventUnsubscribe(0);
+		FastEventBuffer subscribe = InstallEventSubscribe(subscribeStore, 0);
+		FastEventBuffer unsubscribe = InstallEventUnsubscribe(unsubscribeStore, 0);
 
 		subscribe.Append("E", this, SampleMethod);
 		unsubscribe.Append("E", this, SampleMethod);
@@ -27,7 +27,7 @@ public async Task FastEventBuffer_AppendBoxed_KindMatters()
 	public async Task FastEventBuffer_AppendBoxedUnverified_ShouldSkipMatchedSlots()
 	{
 		FastMockInteractions store = new(1);
-		FastEventBuffer buffer = store.InstallEventSubscribe(0);
+		FastEventBuffer buffer = InstallEventSubscribe(store, 0);
 		buffer.Append("E", this, SampleMethod);
 		buffer.Append("E", this, SampleMethod);
 		buffer.Append("E", this, SampleMethod);
@@ -53,7 +53,7 @@ public async Task FastEventBuffer_Subscribe_AppendBoxed_CachesAndReusesAlreadyBo
 		// Pins the `r.Boxed ??= new EventSubscription(...)` cache in AppendBoxed. With the
 		// `??=` mutated to `=`, every AppendBoxed call would allocate a fresh record.
 		FastMockInteractions store = new(1);
-		FastEventBuffer buffer = store.InstallEventSubscribe(0);
+		FastEventBuffer buffer = InstallEventSubscribe(store, 0);
 		buffer.Append("E", this, SampleMethod);
 
 		List<(long Seq, IInteraction Interaction)> first = [];
@@ -71,7 +71,7 @@ public async Task FastEventBuffer_Subscribe_AppendBoxedUnverified_CachesAndReuse
 	{
 		// Pins the `r.Boxed ??= new EventSubscription(...)` cache in AppendBoxedUnverified.
 		FastMockInteractions store = new(1);
-		FastEventBuffer buffer = store.InstallEventSubscribe(0);
+		FastEventBuffer buffer = InstallEventSubscribe(store, 0);
 		buffer.Append("E", this, SampleMethod);
 
 		List<(long Seq, IInteraction Interaction)> first = [];
@@ -88,7 +88,7 @@ public async Task FastEventBuffer_Subscribe_AppendBoxedUnverified_CachesAndReuse
 	public async Task FastEventBuffer_SubscribeAppend_ShouldRaiseInteractionAdded()
 		=> await VerifyRaisesInteractionAdded(store =>
 		{
-			FastEventBuffer buffer = store.InstallEventSubscribe(0);
+			FastEventBuffer buffer = InstallEventSubscribe(store, 0);
 			return () => buffer.Append("E", this, SampleMethod);
 		});
 
@@ -96,7 +96,7 @@ public async Task FastEventBuffer_SubscribeAppend_ShouldRaiseInteractionAdded()
 	public async Task FastEventBuffer_Unsubscribe_AppendBoxed_CachesAndReusesAlreadyBoxedRecord()
 	{
 		FastMockInteractions store = new(1);
-		FastEventBuffer buffer = store.InstallEventUnsubscribe(0);
+		FastEventBuffer buffer = InstallEventUnsubscribe(store, 0);
 		buffer.Append("E", this, SampleMethod);
 
 		List<(long Seq, IInteraction Interaction)> first = [];
@@ -113,7 +113,7 @@ public async Task FastEventBuffer_Unsubscribe_AppendBoxed_CachesAndReusesAlready
 	public async Task FastEventBuffer_Unsubscribe_AppendBoxedUnverified_CachesAndReusesAlreadyBoxedRecord()
 	{
 		FastMockInteractions store = new(1);
-		FastEventBuffer buffer = store.InstallEventUnsubscribe(0);
+		FastEventBuffer buffer = InstallEventUnsubscribe(store, 0);
 		buffer.Append("E", this, SampleMethod);
 
 		List<(long Seq, IInteraction Interaction)> first = [];
@@ -134,7 +134,7 @@ public async Task FastEventBuffer_Unsubscribe_AppendBoxedUnverified_ShouldBoxAsE
 		// flipped to `(true ? Subscription : Unsubscription)`, an unsubscribe buffer would
 		// surface its records as EventSubscription.
 		FastMockInteractions store = new(1);
-		FastEventBuffer buffer = store.InstallEventUnsubscribe(0);
+		FastEventBuffer buffer = InstallEventUnsubscribe(store, 0);
 		buffer.Append("E", this, SampleMethod);
 
 		List<(long Seq, IInteraction Interaction)> dest = [];
@@ -148,7 +148,7 @@ public async Task FastEventBuffer_Unsubscribe_AppendBoxedUnverified_ShouldBoxAsE
 	public async Task FastEventBuffer_UnsubscribeAppend_ShouldRaiseInteractionAdded()
 		=> await VerifyRaisesInteractionAdded(store =>
 		{
-			FastEventBuffer buffer = store.InstallEventUnsubscribe(0);
+			FastEventBuffer buffer = InstallEventUnsubscribe(store, 0);
 			return () => buffer.Append("E", this, SampleMethod);
 		});
 
@@ -156,7 +156,7 @@ public async Task FastEventBuffer_UnsubscribeAppend_ShouldRaiseInteractionAdded(
 	public async Task FastIndexerGetterBuffer1_Append_ShouldRaiseInteractionAdded()
 		=> await VerifyRaisesInteractionAdded(store =>
 		{
-			FastIndexerGetterBuffer<int> buffer = store.InstallIndexerGetter<int>(0);
+			FastIndexerGetterBuffer<int> buffer = InstallIndexerGetter<int>(store, 0);
 			return () => buffer.Append(1);
 		});
 
@@ -164,7 +164,7 @@ public async Task FastIndexerGetterBuffer1_Append_ShouldRaiseInteractionAdded()
 	public async Task FastIndexerGetterBuffer1_AppendBoxed_CachesAndReusesAlreadyBoxedRecord()
 	{
 		FastMockInteractions store = new(1);
-		FastIndexerGetterBuffer<int> buffer = store.InstallIndexerGetter<int>(0);
+		FastIndexerGetterBuffer<int> buffer = InstallIndexerGetter<int>(store, 0);
 
 		buffer.Append(7);
 
@@ -182,7 +182,7 @@ public async Task FastIndexerGetterBuffer1_AppendBoxed_CachesAndReusesAlreadyBox
 	public async Task FastIndexerGetterBuffer1_AppendBoxedUnverified_CachesAndReusesAlreadyBoxedRecord()
 	{
 		FastMockInteractions store = new(1);
-		FastIndexerGetterBuffer<int> buffer = store.InstallIndexerGetter<int>(0);
+		FastIndexerGetterBuffer<int> buffer = InstallIndexerGetter<int>(store, 0);
 
 		buffer.Append(7);
 
@@ -200,7 +200,7 @@ public async Task FastIndexerGetterBuffer1_AppendBoxedUnverified_CachesAndReuses
 	public async Task FastIndexerGetterBuffer1_AppendWithAccess_ShouldPublishAndRaiseInteractionAdded()
 		=> await VerifyAppendWithAccessPublishesAndRaises(store =>
 		{
-			FastIndexerGetterBuffer<int> buffer = store.InstallIndexerGetter<int>(0);
+			FastIndexerGetterBuffer<int> buffer = InstallIndexerGetter<int>(store, 0);
 			IndexerGetterAccess<int> access = new(7);
 			return (() => buffer.Append(access), () => buffer.Count);
 		});
@@ -209,7 +209,7 @@ public async Task FastIndexerGetterBuffer1_AppendWithAccess_ShouldPublishAndRais
 	public async Task FastIndexerGetterBuffer2_Append_ShouldRaiseInteractionAdded()
 		=> await VerifyRaisesInteractionAdded(store =>
 		{
-			FastIndexerGetterBuffer<int, string> buffer = store.InstallIndexerGetter<int, string>(0);
+			FastIndexerGetterBuffer<int, string> buffer = InstallIndexerGetter<int, string>(store, 0);
 			return () => buffer.Append(1, "a");
 		});
 
@@ -217,7 +217,7 @@ public async Task FastIndexerGetterBuffer2_Append_ShouldRaiseInteractionAdded()
 	public async Task FastIndexerGetterBuffer2_AppendBoxed_CachesAndReusesAlreadyBoxedRecord()
 	{
 		FastMockInteractions store = new(1);
-		FastIndexerGetterBuffer<int, string> buffer = store.InstallIndexerGetter<int, string>(0);
+		FastIndexerGetterBuffer<int, string> buffer = InstallIndexerGetter<int, string>(store, 0);
 
 		buffer.Append(7, "k");
 
@@ -235,7 +235,7 @@ public async Task FastIndexerGetterBuffer2_AppendBoxed_CachesAndReusesAlreadyBox
 	public async Task FastIndexerGetterBuffer2_AppendBoxedUnverified_CachesAndReusesAlreadyBoxedRecord()
 	{
 		FastMockInteractions store = new(1);
-		FastIndexerGetterBuffer<int, string> buffer = store.InstallIndexerGetter<int, string>(0);
+		FastIndexerGetterBuffer<int, string> buffer = InstallIndexerGetter<int, string>(store, 0);
 
 		buffer.Append(7, "k");
 
@@ -253,7 +253,7 @@ public async Task FastIndexerGetterBuffer2_AppendBoxedUnverified_CachesAndReuses
 	public async Task FastIndexerGetterBuffer2_AppendWithAccess_ShouldPublishAndRaiseInteractionAdded()
 		=> await VerifyAppendWithAccessPublishesAndRaises(store =>
 		{
-			FastIndexerGetterBuffer<int, string> buffer = store.InstallIndexerGetter<int, string>(0);
+			FastIndexerGetterBuffer<int, string> buffer = InstallIndexerGetter<int, string>(store, 0);
 			IndexerGetterAccess<int, string> access = new(7, "k");
 			return (() => buffer.Append(access), () => buffer.Count);
 		});
@@ -263,7 +263,7 @@ public async Task FastIndexerGetterBuffer3_Append_ShouldRaiseInteractionAdded()
 		=> await VerifyRaisesInteractionAdded(store =>
 		{
 			FastIndexerGetterBuffer<int, string, bool> buffer =
-				store.InstallIndexerGetter<int, string, bool>(0);
+				InstallIndexerGetter<int, string, bool>(store, 0);
 			return () => buffer.Append(1, "a", true);
 		});
 
@@ -272,7 +272,7 @@ public async Task FastIndexerGetterBuffer3_AppendBoxed_CachesAndReusesAlreadyBox
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerGetterBuffer<int, string, bool> buffer =
-			store.InstallIndexerGetter<int, string, bool>(0);
+			InstallIndexerGetter<int, string, bool>(store, 0);
 
 		buffer.Append(7, "k", true);
 
@@ -291,7 +291,7 @@ public async Task FastIndexerGetterBuffer3_AppendBoxedUnverified_CachesAndReuses
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerGetterBuffer<int, string, bool> buffer =
-			store.InstallIndexerGetter<int, string, bool>(0);
+			InstallIndexerGetter<int, string, bool>(store, 0);
 
 		buffer.Append(7, "k", true);
 
@@ -310,7 +310,7 @@ public async Task FastIndexerGetterBuffer3_AppendWithAccess_ShouldPublishAndRais
 		=> await VerifyAppendWithAccessPublishesAndRaises(store =>
 		{
 			FastIndexerGetterBuffer<int, string, bool> buffer =
-				store.InstallIndexerGetter<int, string, bool>(0);
+				InstallIndexerGetter<int, string, bool>(store, 0);
 			IndexerGetterAccess<int, string, bool> access = new(7, "k", true);
 			return (() => buffer.Append(access), () => buffer.Count);
 		});
@@ -320,7 +320,7 @@ public async Task FastIndexerGetterBuffer4_Append_ShouldRaiseInteractionAdded()
 		=> await VerifyRaisesInteractionAdded(store =>
 		{
 			FastIndexerGetterBuffer<int, string, bool, double> buffer =
-				store.InstallIndexerGetter<int, string, bool, double>(0);
+				InstallIndexerGetter<int, string, bool, double>(store, 0);
 			return () => buffer.Append(1, "a", true, 1.0);
 		});
 
@@ -329,7 +329,7 @@ public async Task FastIndexerGetterBuffer4_AppendBoxed_CachesAndReusesAlreadyBox
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerGetterBuffer<int, string, bool, double> buffer =
-			store.InstallIndexerGetter<int, string, bool, double>(0);
+			InstallIndexerGetter<int, string, bool, double>(store, 0);
 
 		buffer.Append(7, "k", true, 3.14);
 
@@ -348,7 +348,7 @@ public async Task FastIndexerGetterBuffer4_AppendBoxedUnverified_CachesAndReuses
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerGetterBuffer<int, string, bool, double> buffer =
-			store.InstallIndexerGetter<int, string, bool, double>(0);
+			InstallIndexerGetter<int, string, bool, double>(store, 0);
 
 		buffer.Append(7, "k", true, 3.14);
 
@@ -367,7 +367,7 @@ public async Task FastIndexerGetterBuffer4_AppendWithAccess_ShouldPublishAndRais
 		=> await VerifyAppendWithAccessPublishesAndRaises(store =>
 		{
 			FastIndexerGetterBuffer<int, string, bool, double> buffer =
-				store.InstallIndexerGetter<int, string, bool, double>(0);
+				InstallIndexerGetter<int, string, bool, double>(store, 0);
 			IndexerGetterAccess<int, string, bool, double> access = new(7, "k", true, 3.14);
 			return (() => buffer.Append(access), () => buffer.Count);
 		});
@@ -376,7 +376,7 @@ public async Task FastIndexerGetterBuffer4_AppendWithAccess_ShouldPublishAndRais
 	public async Task FastIndexerSetterBuffer1_Append_ShouldRaiseInteractionAdded()
 		=> await VerifyRaisesInteractionAdded(store =>
 		{
-			FastIndexerSetterBuffer<int, string> buffer = store.InstallIndexerSetter<int, string>(0);
+			FastIndexerSetterBuffer<int, string> buffer = InstallIndexerSetter<int, string>(store, 0);
 			return () => buffer.Append(1, "a");
 		});
 
@@ -384,7 +384,7 @@ public async Task FastIndexerSetterBuffer1_Append_ShouldRaiseInteractionAdded()
 	public async Task FastIndexerSetterBuffer1_AppendBoxed_CachesAndReusesAlreadyBoxedRecord()
 	{
 		FastMockInteractions store = new(1);
-		FastIndexerSetterBuffer<int, string> buffer = store.InstallIndexerSetter<int, string>(0);
+		FastIndexerSetterBuffer<int, string> buffer = InstallIndexerSetter<int, string>(store, 0);
 
 		buffer.Append(7, "k");
 
@@ -402,7 +402,7 @@ public async Task FastIndexerSetterBuffer1_AppendBoxed_CachesAndReusesAlreadyBox
 	public async Task FastIndexerSetterBuffer1_AppendBoxedUnverified_CachesAndReusesAlreadyBoxedRecord()
 	{
 		FastMockInteractions store = new(1);
-		FastIndexerSetterBuffer<int, string> buffer = store.InstallIndexerSetter<int, string>(0);
+		FastIndexerSetterBuffer<int, string> buffer = InstallIndexerSetter<int, string>(store, 0);
 
 		buffer.Append(7, "k");
 
@@ -420,7 +420,7 @@ public async Task FastIndexerSetterBuffer1_AppendBoxedUnverified_CachesAndReuses
 	public async Task FastIndexerSetterBuffer1_AppendWithAccess_ShouldPublishAndRaiseInteractionAdded()
 		=> await VerifyAppendWithAccessPublishesAndRaises(store =>
 		{
-			FastIndexerSetterBuffer<int, string> buffer = store.InstallIndexerSetter<int, string>(0);
+			FastIndexerSetterBuffer<int, string> buffer = InstallIndexerSetter<int, string>(store, 0);
 			IndexerSetterAccess<int, string> access = new(7, "k");
 			return (() => buffer.Append(access), () => buffer.Count);
 		});
@@ -430,7 +430,7 @@ public async Task FastIndexerSetterBuffer2_Append_ShouldRaiseInteractionAdded()
 		=> await VerifyRaisesInteractionAdded(store =>
 		{
 			FastIndexerSetterBuffer<int, string, bool> buffer =
-				store.InstallIndexerSetter<int, string, bool>(0);
+				InstallIndexerSetter<int, string, bool>(store, 0);
 			return () => buffer.Append(1, "a", true);
 		});
 
@@ -439,7 +439,7 @@ public async Task FastIndexerSetterBuffer2_AppendBoxed_CachesAndReusesAlreadyBox
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerSetterBuffer<int, string, bool> buffer =
-			store.InstallIndexerSetter<int, string, bool>(0);
+			InstallIndexerSetter<int, string, bool>(store, 0);
 
 		buffer.Append(7, "k", true);
 
@@ -458,7 +458,7 @@ public async Task FastIndexerSetterBuffer2_AppendBoxedUnverified_CachesAndReuses
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerSetterBuffer<int, string, bool> buffer =
-			store.InstallIndexerSetter<int, string, bool>(0);
+			InstallIndexerSetter<int, string, bool>(store, 0);
 
 		buffer.Append(7, "k", true);
 
@@ -477,7 +477,7 @@ public async Task FastIndexerSetterBuffer2_AppendWithAccess_ShouldPublishAndRais
 		=> await VerifyAppendWithAccessPublishesAndRaises(store =>
 		{
 			FastIndexerSetterBuffer<int, string, bool> buffer =
-				store.InstallIndexerSetter<int, string, bool>(0);
+				InstallIndexerSetter<int, string, bool>(store, 0);
 			IndexerSetterAccess<int, string, bool> access = new(7, "k", true);
 			return (() => buffer.Append(access), () => buffer.Count);
 		});
@@ -487,7 +487,7 @@ public async Task FastIndexerSetterBuffer3_Append_ShouldRaiseInteractionAdded()
 		=> await VerifyRaisesInteractionAdded(store =>
 		{
 			FastIndexerSetterBuffer<int, string, bool, double> buffer =
-				store.InstallIndexerSetter<int, string, bool, double>(0);
+				InstallIndexerSetter<int, string, bool, double>(store, 0);
 			return () => buffer.Append(1, "a", true, 1.0);
 		});
 
@@ -496,7 +496,7 @@ public async Task FastIndexerSetterBuffer3_AppendBoxed_CachesAndReusesAlreadyBox
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerSetterBuffer<int, string, bool, double> buffer =
-			store.InstallIndexerSetter<int, string, bool, double>(0);
+			InstallIndexerSetter<int, string, bool, double>(store, 0);
 
 		buffer.Append(7, "k", true, 3.14);
 
@@ -515,7 +515,7 @@ public async Task FastIndexerSetterBuffer3_AppendBoxedUnverified_CachesAndReuses
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerSetterBuffer<int, string, bool, double> buffer =
-			store.InstallIndexerSetter<int, string, bool, double>(0);
+			InstallIndexerSetter<int, string, bool, double>(store, 0);
 
 		buffer.Append(7, "k", true, 3.14);
 
@@ -534,7 +534,7 @@ public async Task FastIndexerSetterBuffer3_AppendWithAccess_ShouldPublishAndRais
 		=> await VerifyAppendWithAccessPublishesAndRaises(store =>
 		{
 			FastIndexerSetterBuffer<int, string, bool, double> buffer =
-				store.InstallIndexerSetter<int, string, bool, double>(0);
+				InstallIndexerSetter<int, string, bool, double>(store, 0);
 			IndexerSetterAccess<int, string, bool, double> access = new(7, "k", true, 3.14);
 			return (() => buffer.Append(access), () => buffer.Count);
 		});
@@ -544,7 +544,7 @@ public async Task FastIndexerSetterBuffer4_Append_ShouldRaiseInteractionAdded()
 		=> await VerifyRaisesInteractionAdded(store =>
 		{
 			FastIndexerSetterBuffer<int, string, bool, double, char> buffer =
-				store.InstallIndexerSetter<int, string, bool, double, char>(0);
+				InstallIndexerSetter<int, string, bool, double, char>(store, 0);
 			return () => buffer.Append(1, "a", true, 1.0, 'x');
 		});
 
@@ -553,7 +553,7 @@ public async Task FastIndexerSetterBuffer4_AppendBoxed_CachesAndReusesAlreadyBox
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerSetterBuffer<int, string, bool, double, char> buffer =
-			store.InstallIndexerSetter<int, string, bool, double, char>(0);
+			InstallIndexerSetter<int, string, bool, double, char>(store, 0);
 
 		buffer.Append(7, "k", true, 3.14, 'z');
 
@@ -572,7 +572,7 @@ public async Task FastIndexerSetterBuffer4_AppendBoxedUnverified_CachesAndReuses
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerSetterBuffer<int, string, bool, double, char> buffer =
-			store.InstallIndexerSetter<int, string, bool, double, char>(0);
+			InstallIndexerSetter<int, string, bool, double, char>(store, 0);
 
 		buffer.Append(7, "k", true, 3.14, 'z');
 
@@ -591,7 +591,7 @@ public async Task FastIndexerSetterBuffer4_AppendWithAccess_ShouldPublishAndRais
 		=> await VerifyAppendWithAccessPublishesAndRaises(store =>
 		{
 			FastIndexerSetterBuffer<int, string, bool, double, char> buffer =
-				store.InstallIndexerSetter<int, string, bool, double, char>(0);
+				InstallIndexerSetter<int, string, bool, double, char>(store, 0);
 			IndexerSetterAccess<int, string, bool, double, char> access = new(7, "k", true, 3.14, 'z');
 			return (() => buffer.Append(access), () => buffer.Count);
 		});
@@ -601,7 +601,8 @@ public async Task FastMethod0Buffer_AppendBoxed_CachesAndReusesAlreadyBoxedRecor
 	{
 		// Pins the `r.Boxed ??= new MethodInvocation(r.Name)` cache in Method0 AppendBoxed.
 		FastMockInteractions store = new(1);
-		FastMethod0Buffer buffer = store.InstallMethod(0);
+		FastMethod0Buffer buffer = store.GetOrCreateBuffer<FastMethod0Buffer>(0,
+			static f => new FastMethod0Buffer(f));
 
 		buffer.Append("M");
 
@@ -619,7 +620,8 @@ public async Task FastMethod0Buffer_AppendBoxed_CachesAndReusesAlreadyBoxedRecor
 	public async Task FastMethod1Buffer_Append_ShouldRaiseInteractionAdded()
 		=> await VerifyRaisesInteractionAdded(store =>
 		{
-			FastMethod1Buffer<int> buffer = store.InstallMethod<int>(0);
+			FastMethod1Buffer<int> buffer = store.GetOrCreateBuffer<FastMethod1Buffer<int>>(0,
+				static f => new FastMethod1Buffer<int>(f));
 			return () => buffer.Append("M", 1);
 		});
 
@@ -627,7 +629,8 @@ public async Task FastMethod1Buffer_Append_ShouldRaiseInteractionAdded()
 	public async Task FastMethod1Buffer_AppendBoxed_CachesAndReusesAlreadyBoxedRecord()
 	{
 		FastMockInteractions store = new(1);
-		FastMethod1Buffer<int> buffer = store.InstallMethod<int>(0);
+		FastMethod1Buffer<int> buffer = store.GetOrCreateBuffer<FastMethod1Buffer<int>>(0,
+			static f => new FastMethod1Buffer<int>(f));
 
 		buffer.Append("M", 1);
 
@@ -645,7 +648,8 @@ public async Task FastMethod1Buffer_AppendBoxed_CachesAndReusesAlreadyBoxedRecor
 	public async Task FastMethod2Buffer_Append_ShouldRaiseInteractionAdded()
 		=> await VerifyRaisesInteractionAdded(store =>
 		{
-			FastMethod2Buffer<int, string> buffer = store.InstallMethod<int, string>(0);
+			FastMethod2Buffer<int, string> buffer = store.GetOrCreateBuffer<FastMethod2Buffer<int, string>>(0,
+				static f => new FastMethod2Buffer<int, string>(f));
 			return () => buffer.Append("M", 1, "a");
 		});
 
@@ -653,7 +657,7 @@ public async Task FastMethod2Buffer_Append_ShouldRaiseInteractionAdded()
 	public async Task FastMethod3Buffer_Append_ShouldRaiseInteractionAdded()
 		=> await VerifyRaisesInteractionAdded(store =>
 		{
-			FastMethod3Buffer<int, string, bool> buffer = store.InstallMethod<int, string, bool>(0);
+			FastMethod3Buffer<int, string, bool> buffer = InstallMethod<int, string, bool>(store, 0);
 			return () => buffer.Append("M", 1, "a", true);
 		});
 
@@ -662,7 +666,7 @@ public async Task FastMethod3Buffer_AppendBoxed_CachesAndReusesAlreadyBoxedRecor
 	{
 		// Pins the `r.Boxed ??= new MethodInvocation<T1,T2,T3>(...)` cache in Method3 AppendBoxed.
 		FastMockInteractions store = new(1);
-		FastMethod3Buffer<int, string, bool> buffer = store.InstallMethod<int, string, bool>(0);
+		FastMethod3Buffer<int, string, bool> buffer = InstallMethod<int, string, bool>(store, 0);
 
 		buffer.Append("M", 1, "a", true);
 
@@ -681,7 +685,7 @@ public async Task FastMethod3Buffer_AppendBoxedUnverified_CachesAndReusesAlready
 	{
 		// Pins the `r.Boxed ??= new MethodInvocation<T1,T2,T3>(...)` cache in Method3 AppendBoxedUnverified.
 		FastMockInteractions store = new(1);
-		FastMethod3Buffer<int, string, bool> buffer = store.InstallMethod<int, string, bool>(0);
+		FastMethod3Buffer<int, string, bool> buffer = InstallMethod<int, string, bool>(store, 0);
 
 		buffer.Append("M", 1, "a", true);
 
@@ -699,7 +703,7 @@ public async Task FastMethod3Buffer_AppendBoxedUnverified_CachesAndReusesAlready
 	public async Task FastMethod3Buffer_AppendBoxedUnverified_ShouldSkipMatchedSlots()
 	{
 		FastMockInteractions store = new(1);
-		FastMethod3Buffer<int, string, bool> buffer = store.InstallMethod<int, string, bool>(0);
+		FastMethod3Buffer<int, string, bool> buffer = InstallMethod<int, string, bool>(store, 0);
 		buffer.Append("M", 0, "a", true);
 		buffer.Append("M", 1, "b", false);
 		buffer.Append("M", 2, "c", true);
@@ -722,7 +726,7 @@ public async Task FastMethod4Buffer_Append_ShouldRaiseInteractionAdded()
 		=> await VerifyRaisesInteractionAdded(store =>
 		{
 			FastMethod4Buffer<int, string, bool, double> buffer =
-				store.InstallMethod<int, string, bool, double>(0);
+				InstallMethod<int, string, bool, double>(store, 0);
 			return () => buffer.Append("M", 1, "a", true, 1.0);
 		});
 
@@ -732,7 +736,7 @@ public async Task FastMethod4Buffer_AppendBoxed_CachesAndReusesAlreadyBoxedRecor
 		// Pins the `r.Boxed ??= new MethodInvocation<T1,T2,T3,T4>(...)` cache in Method4 AppendBoxed.
 		FastMockInteractions store = new(1);
 		FastMethod4Buffer<int, string, bool, double> buffer =
-			store.InstallMethod<int, string, bool, double>(0);
+			InstallMethod<int, string, bool, double>(store, 0);
 
 		buffer.Append("M", 1, "a", true, 1.0);
 
@@ -752,7 +756,7 @@ public async Task FastMethod4Buffer_AppendBoxedUnverified_CachesAndReusesAlready
 		// Pins the `r.Boxed ??= new MethodInvocation<T1,T2,T3,T4>(...)` cache in Method4 AppendBoxedUnverified.
 		FastMockInteractions store = new(1);
 		FastMethod4Buffer<int, string, bool, double> buffer =
-			store.InstallMethod<int, string, bool, double>(0);
+			InstallMethod<int, string, bool, double>(store, 0);
 
 		buffer.Append("M", 1, "a", true, 1.0);
 
@@ -771,7 +775,7 @@ public async Task FastMethod4Buffer_AppendBoxedUnverified_ShouldSkipMatchedSlots
 	{
 		FastMockInteractions store = new(1);
 		FastMethod4Buffer<int, string, bool, double> buffer =
-			store.InstallMethod<int, string, bool, double>(0);
+			InstallMethod<int, string, bool, double>(store, 0);
 		buffer.Append("M", 0, "a", true, 0.5);
 		buffer.Append("M", 1, "b", false, 1.5);
 		buffer.Append("M", 2, "c", true, 2.5);
@@ -794,49 +798,17 @@ public async Task FastMethod4Buffer_AppendBoxedUnverified_ShouldSkipMatchedSlots
 	public async Task FastPropertyGetterBuffer_Append_ShouldRaiseInteractionAdded()
 		=> await VerifyRaisesInteractionAdded(store =>
 		{
-			FastPropertyGetterBuffer buffer = store.InstallPropertyGetter(0);
-			return () => buffer.Append("P");
+			FastPropertyGetterBuffer buffer = InstallPropertyGetter(store, 0);
+			return () => buffer.Append();
 		});
 
-	[Fact]
-	public async Task FastPropertyGetterBuffer_Append_WithoutInstalledSingleton_ShouldIncludeFactoryGuidanceInMessage()
-	{
-		// Kills the `$"..."` -> `$""` string mutation on the InvalidOperationException message.
-		// The message points callers at the correct factory overload — without it, the failure
-		// is just an empty-string IOE, which is useless guidance.
-		FastMockInteractions store = new(1);
-		FastPropertyGetterBuffer buffer = store.InstallPropertyGetter(0);
-
-		void Act()
-		{
-			buffer.Append();
-		}
-
-		await That(Act).Throws<InvalidOperationException>()
-			.WithMessage("*InstallPropertyGetter*").AsWildcard();
-	}
-
-	[Fact]
-	public async Task FastPropertyGetterBuffer_Append_WithoutInstalledSingleton_ShouldThrow()
-	{
-		FastMockInteractions store = new(1);
-		FastPropertyGetterBuffer buffer = store.InstallPropertyGetter(0);
-
-		void Act()
-		{
-			buffer.Append();
-		}
-
-		await That(Act).Throws<InvalidOperationException>();
-	}
-
 	[Fact]
 	public async Task FastPropertyGetterBuffer_AppendBoxed_RepeatedCallsReturnSameSingleton()
 	{
 		FastMockInteractions store = new(1);
-		FastPropertyGetterBuffer buffer = store.InstallPropertyGetter(0);
+		FastPropertyGetterBuffer buffer = InstallPropertyGetter(store, 0);
 
-		buffer.Append("P");
+		buffer.Append();
 
 		List<(long Seq, IInteraction Interaction)> first = [];
 		List<(long Seq, IInteraction Interaction)> second = [];
@@ -858,10 +830,10 @@ public async Task FastPropertyGetterBuffer_AppendBoxed_SharesSingletonAcrossReco
 		// shared identity (the Then walker is positional, the verified filter is
 		// all-or-nothing per matched property).
 		FastMockInteractions store = new(1);
-		FastPropertyGetterBuffer buffer = store.InstallPropertyGetter(0);
+		FastPropertyGetterBuffer buffer = InstallPropertyGetter(store, 0);
 
-		buffer.Append("P");
-		buffer.Append("P");
+		buffer.Append();
+		buffer.Append();
 
 		List<(long Seq, IInteraction Interaction)> dest = [];
 		((IFastMemberBuffer)buffer).AppendBoxed(dest);
@@ -874,13 +846,13 @@ public async Task FastPropertyGetterBuffer_AppendBoxed_SharesSingletonAcrossReco
 	public async Task FastPropertyGetterBuffer_AppendString_LazyInitsAccessOnce()
 	{
 		FastMockInteractions store = new(1);
-		FastPropertyGetterBuffer buffer = store.InstallPropertyGetter(0);
+		FastPropertyGetterBuffer buffer = InstallPropertyGetter(store, 0);
 
-		buffer.Append("P");
+		buffer.Append();
 		List<(long Seq, IInteraction Interaction)> firstSnapshot = [];
 		((IFastMemberBuffer)buffer).AppendBoxed(firstSnapshot);
 
-		buffer.Append("P");
+		buffer.Append();
 		List<(long Seq, IInteraction Interaction)> secondSnapshot = [];
 		((IFastMemberBuffer)buffer).AppendBoxed(secondSnapshot);
 
@@ -894,7 +866,7 @@ public async Task FastPropertyGetterBuffer_AppendString_LazyInitsAccessOnce()
 	public async Task FastPropertySetterBuffer_Append_ShouldRaiseInteractionAdded()
 		=> await VerifyRaisesInteractionAdded(store =>
 		{
-			FastPropertySetterBuffer<int> buffer = store.InstallPropertySetter<int>(0);
+			FastPropertySetterBuffer<int> buffer = InstallPropertySetter<int>(store, 0);
 			return () => buffer.Append("P", 1);
 		});
 
@@ -902,7 +874,7 @@ public async Task FastPropertySetterBuffer_Append_ShouldRaiseInteractionAdded()
 	public async Task FastPropertySetterBuffer_AppendBoxed_CachesAndReusesAlreadyBoxedRecord()
 	{
 		FastMockInteractions store = new(1);
-		FastPropertySetterBuffer<int> buffer = store.InstallPropertySetter<int>(0);
+		FastPropertySetterBuffer<int> buffer = InstallPropertySetter<int>(store, 0);
 
 		buffer.Append("P", 5);
 
@@ -922,7 +894,7 @@ public async Task FastPropertySetterBuffer_AppendBoxedUnverified_CachesAndReuses
 		// Mirrors the AppendBoxed caching test for the Unverified path so the `r.Boxed ??= new
 		// PropertySetterAccess<T>(...)` mutation is killed there as well.
 		FastMockInteractions store = new(1);
-		FastPropertySetterBuffer<int> buffer = store.InstallPropertySetter<int>(0);
+		FastPropertySetterBuffer<int> buffer = InstallPropertySetter<int>(store, 0);
 
 		buffer.Append("P", 5);
 
@@ -941,7 +913,7 @@ public async Task FastPropertySetterBuffer_AppendBoxedUnverified_ShouldSkipMatch
 	{
 		// Covers the AppendBoxedUnverified branch on the setter buffer (NoCoverage cluster).
 		FastMockInteractions store = new(1);
-		FastPropertySetterBuffer<int> buffer = store.InstallPropertySetter<int>(0);
+		FastPropertySetterBuffer<int> buffer = InstallPropertySetter<int>(store, 0);
 		buffer.Append("P", 1);
 		buffer.Append("P", 2);
 		buffer.Append("P", 3);
@@ -963,7 +935,7 @@ public async Task FastPropertySetterBuffer_ConsumeMatching_ShouldMarkSlotsVerifi
 		// to `false`, ConsumeMatching would still report matches but the slots would never be
 		// marked verified — so a second ConsumeMatching call would re-count the same records.
 		FastMockInteractions store = new(1);
-		FastPropertySetterBuffer<int> buffer = store.InstallPropertySetter<int>(0);
+		FastPropertySetterBuffer<int> buffer = InstallPropertySetter<int>(store, 0);
 		buffer.Append("P", 1);
 		buffer.Append("P", 1);
 
@@ -980,7 +952,7 @@ public async Task FastPropertySetterBuffer_ConsumeMatching_ShouldMarkSlotsVerifi
 	public async Task IndexerGetterBuffer1_AppendBoxedUnverified_ShouldSkipMatchedSlots()
 	{
 		FastMockInteractions store = new(1);
-		FastIndexerGetterBuffer<int> buffer = store.InstallIndexerGetter<int>(0);
+		FastIndexerGetterBuffer<int> buffer = InstallIndexerGetter<int>(store, 0);
 		buffer.Append(0);
 		buffer.Append(1);
 		buffer.Append(2);
@@ -999,7 +971,7 @@ public async Task IndexerGetterBuffer1_AppendBoxedUnverified_ShouldSkipMatchedSl
 	public async Task IndexerGetterBuffer2_AppendBoxedUnverified_ShouldSkipMatchedSlots()
 	{
 		FastMockInteractions store = new(1);
-		FastIndexerGetterBuffer<int, string> buffer = store.InstallIndexerGetter<int, string>(0);
+		FastIndexerGetterBuffer<int, string> buffer = InstallIndexerGetter<int, string>(store, 0);
 		buffer.Append(0, "a");
 		buffer.Append(1, "b");
 		buffer.Append(2, "c");
@@ -1021,7 +993,7 @@ public async Task IndexerGetterBuffer3_AppendBoxed_BoxesAsIndexerGetterAccess()
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerGetterBuffer<int, string, bool> buffer =
-			store.InstallIndexerGetter<int, string, bool>(0);
+			InstallIndexerGetter<int, string, bool>(store, 0);
 
 		buffer.Append(7, "k", true);
 
@@ -1037,7 +1009,7 @@ public async Task IndexerGetterBuffer3_AppendBoxedUnverified_ShouldSkipMatchedSl
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerGetterBuffer<int, string, bool> buffer =
-			store.InstallIndexerGetter<int, string, bool>(0);
+			InstallIndexerGetter<int, string, bool>(store, 0);
 		buffer.Append(0, "a", true);
 		buffer.Append(1, "b", false);
 		buffer.Append(2, "c", true);
@@ -1060,7 +1032,7 @@ public async Task IndexerGetterBuffer4_AppendBoxed_BoxesAsIndexerGetterAccess()
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerGetterBuffer<int, string, bool, double> buffer =
-			store.InstallIndexerGetter<int, string, bool, double>(0);
+			InstallIndexerGetter<int, string, bool, double>(store, 0);
 
 		buffer.Append(7, "k", true, 3.14);
 
@@ -1077,7 +1049,7 @@ public async Task IndexerGetterBuffer4_AppendBoxedUnverified_ShouldSkipMatchedSl
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerGetterBuffer<int, string, bool, double> buffer =
-			store.InstallIndexerGetter<int, string, bool, double>(0);
+			InstallIndexerGetter<int, string, bool, double>(store, 0);
 		buffer.Append(0, "a", true, 0.5);
 		buffer.Append(1, "b", false, 1.5);
 		buffer.Append(2, "c", true, 2.5);
@@ -1100,7 +1072,7 @@ public async Task IndexerGetterBuffer4_AppendBoxedUnverified_ShouldSkipMatchedSl
 	public async Task IndexerSetterBuffer1_AppendBoxedUnverified_ShouldSkipMatchedSlots()
 	{
 		FastMockInteractions store = new(1);
-		FastIndexerSetterBuffer<int, string> buffer = store.InstallIndexerSetter<int, string>(0);
+		FastIndexerSetterBuffer<int, string> buffer = InstallIndexerSetter<int, string>(store, 0);
 		buffer.Append(0, "x");
 		buffer.Append(1, "y");
 		buffer.Append(2, "z");
@@ -1122,7 +1094,7 @@ public async Task IndexerSetterBuffer2_AppendBoxedUnverified_ShouldSkipMatchedSl
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerSetterBuffer<int, string, bool> buffer =
-			store.InstallIndexerSetter<int, string, bool>(0);
+			InstallIndexerSetter<int, string, bool>(store, 0);
 		buffer.Append(0, "x", true);
 		buffer.Append(1, "y", false);
 		buffer.Append(2, "z", true);
@@ -1145,7 +1117,7 @@ public async Task IndexerSetterBuffer3_AppendBoxed_BoxesAsIndexerSetterAccess()
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerSetterBuffer<int, string, bool, double> buffer =
-			store.InstallIndexerSetter<int, string, bool, double>(0);
+			InstallIndexerSetter<int, string, bool, double>(store, 0);
 
 		buffer.Append(7, "k", true, 3.14);
 
@@ -1162,7 +1134,7 @@ public async Task IndexerSetterBuffer3_AppendBoxedUnverified_ShouldSkipMatchedSl
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerSetterBuffer<int, string, bool, double> buffer =
-			store.InstallIndexerSetter<int, string, bool, double>(0);
+			InstallIndexerSetter<int, string, bool, double>(store, 0);
 		buffer.Append(0, "x", true, 0.5);
 		buffer.Append(1, "y", false, 1.5);
 		buffer.Append(2, "z", true, 2.5);
@@ -1186,7 +1158,7 @@ public async Task IndexerSetterBuffer4_AppendBoxed_BoxesAsIndexerSetterAccess()
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerSetterBuffer<int, string, bool, double, char> buffer =
-			store.InstallIndexerSetter<int, string, bool, double, char>(0);
+			InstallIndexerSetter<int, string, bool, double, char>(store, 0);
 
 		buffer.Append(7, "k", true, 3.14, 'z');
 
@@ -1204,7 +1176,7 @@ public async Task IndexerSetterBuffer4_AppendBoxedUnverified_ShouldSkipMatchedSl
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerSetterBuffer<int, string, bool, double, char> buffer =
-			store.InstallIndexerSetter<int, string, bool, double, char>(0);
+			InstallIndexerSetter<int, string, bool, double, char>(store, 0);
 		buffer.Append(0, "x", true, 0.5, 'a');
 		buffer.Append(1, "y", false, 1.5, 'b');
 		buffer.Append(2, "z", true, 2.5, 'c');
@@ -1224,6 +1196,62 @@ public async Task IndexerSetterBuffer4_AppendBoxedUnverified_ShouldSkipMatchedSl
 		await That(((IndexerSetterAccess<int, string, bool, double, char>)dest[1].Interaction).Parameter1).IsEqualTo(2);
 	}
 
+	private static FastMethod3Buffer<T1, T2, T3> InstallMethod<T1, T2, T3>(FastMockInteractions store, int memberId)
+		=> store.GetOrCreateBuffer<FastMethod3Buffer<T1, T2, T3>>(memberId,
+			static f => new FastMethod3Buffer<T1, T2, T3>(f));
+
+	private static FastMethod4Buffer<T1, T2, T3, T4> InstallMethod<T1, T2, T3, T4>(FastMockInteractions store, int memberId)
+		=> store.GetOrCreateBuffer<FastMethod4Buffer<T1, T2, T3, T4>>(memberId,
+			static f => new FastMethod4Buffer<T1, T2, T3, T4>(f));
+
+	private static FastIndexerGetterBuffer<T1> InstallIndexerGetter<T1>(FastMockInteractions store, int memberId)
+		=> store.GetOrCreateBuffer<FastIndexerGetterBuffer<T1>>(memberId,
+			static f => new FastIndexerGetterBuffer<T1>(f));
+
+	private static FastIndexerGetterBuffer<T1, T2> InstallIndexerGetter<T1, T2>(FastMockInteractions store, int memberId)
+		=> store.GetOrCreateBuffer<FastIndexerGetterBuffer<T1, T2>>(memberId,
+			static f => new FastIndexerGetterBuffer<T1, T2>(f));
+
+	private static FastIndexerGetterBuffer<T1, T2, T3> InstallIndexerGetter<T1, T2, T3>(FastMockInteractions store, int memberId)
+		=> store.GetOrCreateBuffer<FastIndexerGetterBuffer<T1, T2, T3>>(memberId,
+			static f => new FastIndexerGetterBuffer<T1, T2, T3>(f));
+
+	private static FastIndexerGetterBuffer<T1, T2, T3, T4> InstallIndexerGetter<T1, T2, T3, T4>(FastMockInteractions store, int memberId)
+		=> store.GetOrCreateBuffer<FastIndexerGetterBuffer<T1, T2, T3, T4>>(memberId,
+			static f => new FastIndexerGetterBuffer<T1, T2, T3, T4>(f));
+
+	private static FastIndexerSetterBuffer<T1, TValue> InstallIndexerSetter<T1, TValue>(FastMockInteractions store, int memberId)
+		=> store.GetOrCreateBuffer<FastIndexerSetterBuffer<T1, TValue>>(memberId,
+			static f => new FastIndexerSetterBuffer<T1, TValue>(f));
+
+	private static FastIndexerSetterBuffer<T1, T2, TValue> InstallIndexerSetter<T1, T2, TValue>(FastMockInteractions store, int memberId)
+		=> store.GetOrCreateBuffer<FastIndexerSetterBuffer<T1, T2, TValue>>(memberId,
+			static f => new FastIndexerSetterBuffer<T1, T2, TValue>(f));
+
+	private static FastIndexerSetterBuffer<T1, T2, T3, TValue> InstallIndexerSetter<T1, T2, T3, TValue>(FastMockInteractions store, int memberId)
+		=> store.GetOrCreateBuffer<FastIndexerSetterBuffer<T1, T2, T3, TValue>>(memberId,
+			static f => new FastIndexerSetterBuffer<T1, T2, T3, TValue>(f));
+
+	private static FastIndexerSetterBuffer<T1, T2, T3, T4, TValue> InstallIndexerSetter<T1, T2, T3, T4, TValue>(FastMockInteractions store, int memberId)
+		=> store.GetOrCreateBuffer<FastIndexerSetterBuffer<T1, T2, T3, T4, TValue>>(memberId,
+			static f => new FastIndexerSetterBuffer<T1, T2, T3, T4, TValue>(f));
+
+	private static FastEventBuffer InstallEventSubscribe(FastMockInteractions store, int memberId)
+		=> store.GetOrCreateBuffer<FastEventBuffer>(memberId,
+			static f => new FastEventBuffer(f, FastEventBufferKind.Subscribe));
+
+	private static FastEventBuffer InstallEventUnsubscribe(FastMockInteractions store, int memberId)
+		=> store.GetOrCreateBuffer<FastEventBuffer>(memberId,
+			static f => new FastEventBuffer(f, FastEventBufferKind.Unsubscribe));
+
+	private static FastPropertyGetterBuffer InstallPropertyGetter(FastMockInteractions store, int memberId)
+		=> store.GetOrCreateBuffer<FastPropertyGetterBuffer>(memberId,
+			static f => new FastPropertyGetterBuffer(f, new PropertyGetterAccess(string.Empty)));
+
+	private static FastPropertySetterBuffer<T> InstallPropertySetter<T>(FastMockInteractions store, int memberId)
+		=> store.GetOrCreateBuffer<FastPropertySetterBuffer<T>>(memberId,
+			static f => new FastPropertySetterBuffer<T>(f));
+
 	private static async Task VerifyAppendWithAccessPublishesAndRaises(
 		Func<FastMockInteractions, (Action Append, Func<int> CountReader)> setupFactory)
 	{
diff --git a/Tests/Mockolate.Internal.Tests/Interactions/FastBufferConcurrencyTests.cs b/Tests/Mockolate.Internal.Tests/Interactions/FastBufferConcurrencyTests.cs
index e0cb512d..c97bf0a4 100644
--- a/Tests/Mockolate.Internal.Tests/Interactions/FastBufferConcurrencyTests.cs
+++ b/Tests/Mockolate.Internal.Tests/Interactions/FastBufferConcurrencyTests.cs
@@ -13,7 +13,8 @@ public async Task FastMethod1Buffer_ConcurrentAppend_ShouldRecordAllInteractions
 		const int appendsPerWriter = 1000;
 
 		FastMockInteractions store = new(1);
-		FastMethod1Buffer<int> buffer = store.InstallMethod<int>(0);
+		FastMethod1Buffer<int> buffer = store.GetOrCreateBuffer<FastMethod1Buffer<int>>(0,
+			static f => new FastMethod1Buffer<int>(f));
 #if NET48
 		CancellationToken cancellationToken = TestContext.Current.CancellationToken;
 #else
@@ -44,7 +45,8 @@ await That(buffer.ConsumeMatching((IParameterMatch<int>)It.IsAny<int>()))
 	public async Task FastMethod1Buffer_InteractionAdded_ShouldFireWhenSubscribed()
 	{
 		FastMockInteractions store = new(1);
-		FastMethod1Buffer<int> buffer = store.InstallMethod<int>(0);
+		FastMethod1Buffer<int> buffer = store.GetOrCreateBuffer<FastMethod1Buffer<int>>(0,
+			static f => new FastMethod1Buffer<int>(f));
 
 		int invocations = 0;
 
diff --git a/Tests/Mockolate.Internal.Tests/Interactions/FastBufferConsumeMatchingTests.cs b/Tests/Mockolate.Internal.Tests/Interactions/FastBufferConsumeMatchingTests.cs
index cb547930..f09ebb60 100644
--- a/Tests/Mockolate.Internal.Tests/Interactions/FastBufferConsumeMatchingTests.cs
+++ b/Tests/Mockolate.Internal.Tests/Interactions/FastBufferConsumeMatchingTests.cs
@@ -10,7 +10,8 @@ public class FastBufferConsumeMatchingTests
 	public async Task FastEventBuffer_ConsumeMatching_ShouldReturnCount()
 	{
 		FastMockInteractions store = new(1);
-		FastEventBuffer buffer = store.InstallEventSubscribe(0);
+		FastEventBuffer buffer = store.GetOrCreateBuffer<FastEventBuffer>(0,
+			static f => new FastEventBuffer(f, FastEventBufferKind.Subscribe));
 
 		await That(buffer.ConsumeMatching()).IsEqualTo(0);
 
@@ -26,7 +27,8 @@ public async Task FastEventBuffer_ConsumeMatching_ShouldReturnCount()
 	public async Task FastIndexerGetterBuffer1_ConsumeMatching_ShouldHonorMatcher()
 	{
 		FastMockInteractions store = new(1);
-		FastIndexerGetterBuffer<int> buffer = store.InstallIndexerGetter<int>(0);
+		FastIndexerGetterBuffer<int> buffer = store.GetOrCreateBuffer<FastIndexerGetterBuffer<int>>(0,
+			static f => new FastIndexerGetterBuffer<int>(f));
 
 		buffer.Append(1);
 		buffer.Append(2);
@@ -41,7 +43,8 @@ public async Task FastIndexerGetterBuffer1_ConsumeMatching_ShouldHonorMatcher()
 	public async Task FastIndexerGetterBuffer2_ConsumeMatching_ShouldHonorAllMatchers()
 	{
 		FastMockInteractions store = new(1);
-		FastIndexerGetterBuffer<int, string> buffer = store.InstallIndexerGetter<int, string>(0);
+		FastIndexerGetterBuffer<int, string> buffer = store.GetOrCreateBuffer<FastIndexerGetterBuffer<int, string>>(0,
+			static f => new FastIndexerGetterBuffer<int, string>(f));
 
 		buffer.Append(1, "a");
 		buffer.Append(1, "b");
@@ -59,7 +62,9 @@ await That(buffer.ConsumeMatching(
 	public async Task FastIndexerGetterBuffer3_ConsumeMatching_ShouldHonorAllMatchers()
 	{
 		FastMockInteractions store = new(1);
-		FastIndexerGetterBuffer<int, string, bool> buffer = store.InstallIndexerGetter<int, string, bool>(0);
+		FastIndexerGetterBuffer<int, string, bool> buffer =
+			store.GetOrCreateBuffer<FastIndexerGetterBuffer<int, string, bool>>(0,
+				static f => new FastIndexerGetterBuffer<int, string, bool>(f));
 
 		buffer.Append(1, "a", true);
 		buffer.Append(2, "a", false);
@@ -84,7 +89,8 @@ public async Task FastIndexerGetterBuffer4_ConsumeMatching_ShouldHonorAllMatcher
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerGetterBuffer<int, string, bool, double> buffer =
-			store.InstallIndexerGetter<int, string, bool, double>(0);
+			store.GetOrCreateBuffer<FastIndexerGetterBuffer<int, string, bool, double>>(0,
+				static f => new FastIndexerGetterBuffer<int, string, bool, double>(f));
 
 		buffer.Append(1, "a", true, 1.0);
 		buffer.Append(1, "b", true, 2.0);
@@ -111,7 +117,8 @@ await That(buffer.ConsumeMatching(
 	public async Task FastIndexerSetterBuffer1_ConsumeMatching_ShouldHonorMatchers()
 	{
 		FastMockInteractions store = new(1);
-		FastIndexerSetterBuffer<int, string> buffer = store.InstallIndexerSetter<int, string>(0);
+		FastIndexerSetterBuffer<int, string> buffer = store.GetOrCreateBuffer<FastIndexerSetterBuffer<int, string>>(0,
+			static f => new FastIndexerSetterBuffer<int, string>(f));
 
 		buffer.Append(1, "a");
 		buffer.Append(1, "b");
@@ -133,7 +140,8 @@ public async Task FastIndexerSetterBuffer2_ConsumeMatching_ShouldHonorAllMatcher
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerSetterBuffer<int, string, bool> buffer =
-			store.InstallIndexerSetter<int, string, bool>(0);
+			store.GetOrCreateBuffer<FastIndexerSetterBuffer<int, string, bool>>(0,
+				static f => new FastIndexerSetterBuffer<int, string, bool>(f));
 
 		buffer.Append(1, "a", true);
 		buffer.Append(1, "b", false);
@@ -158,7 +166,8 @@ public async Task FastIndexerSetterBuffer3_ConsumeMatching_ShouldHonorAllMatcher
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerSetterBuffer<int, string, bool, double> buffer =
-			store.InstallIndexerSetter<int, string, bool, double>(0);
+			store.GetOrCreateBuffer<FastIndexerSetterBuffer<int, string, bool, double>>(0,
+				static f => new FastIndexerSetterBuffer<int, string, bool, double>(f));
 
 		buffer.Append(1, "a", true, 1.0);
 		buffer.Append(1, "b", true, 2.0);
@@ -186,7 +195,8 @@ public async Task FastIndexerSetterBuffer4_ConsumeMatching_ShouldHonorAllMatcher
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerSetterBuffer<int, string, bool, double, char> buffer =
-			store.InstallIndexerSetter<int, string, bool, double, char>(0);
+			store.GetOrCreateBuffer<FastIndexerSetterBuffer<int, string, bool, double, char>>(0,
+				static f => new FastIndexerSetterBuffer<int, string, bool, double, char>(f));
 
 		buffer.Append(1, "a", true, 1.0, 'x');
 		buffer.Append(1, "b", true, 2.0, 'x');
@@ -216,7 +226,8 @@ await That(buffer.ConsumeMatching(
 	public async Task FastMethod0Buffer_ConsumeMatching_ShouldReturnCount()
 	{
 		FastMockInteractions store = new(1);
-		FastMethod0Buffer buffer = store.InstallMethod(0);
+		FastMethod0Buffer buffer = store.GetOrCreateBuffer<FastMethod0Buffer>(0,
+			static f => new FastMethod0Buffer(f));
 
 		await That(buffer.ConsumeMatching()).IsEqualTo(0);
 
@@ -234,7 +245,8 @@ public async Task FastMethod1Buffer_ConsumeAll_OnEmptyBuffer_ShouldReturnZeroWit
 		// buffer (n == 0) would still enter the loop at slot=0 and call VerifiedUnderLock(0),
 		// which dereferences the not-yet-allocated VerifiedChunks[0] → NRE.
 		FastMockInteractions store = new(1);
-		FastMethod1Buffer<int> buffer = store.InstallMethod<int>(0);
+		FastMethod1Buffer<int> buffer = store.GetOrCreateBuffer<FastMethod1Buffer<int>>(0,
+			static f => new FastMethod1Buffer<int>(f));
 
 		int consumed = buffer.ConsumeAll();
 
@@ -245,7 +257,8 @@ public async Task FastMethod1Buffer_ConsumeAll_OnEmptyBuffer_ShouldReturnZeroWit
 	public async Task FastMethod1Buffer_ConsumeMatching_ShouldHonorMatcher()
 	{
 		FastMockInteractions store = new(1);
-		FastMethod1Buffer<int> buffer = store.InstallMethod<int>(0);
+		FastMethod1Buffer<int> buffer = store.GetOrCreateBuffer<FastMethod1Buffer<int>>(0,
+			static f => new FastMethod1Buffer<int>(f));
 
 		buffer.Append("Foo", 1);
 		buffer.Append("Foo", 2);
@@ -260,7 +273,8 @@ public async Task FastMethod1Buffer_ConsumeMatching_ShouldHonorMatcher()
 	public async Task FastMethod2Buffer_ConsumeAll_OnEmptyBuffer_ShouldReturnZeroWithoutThrowing()
 	{
 		FastMockInteractions store = new(1);
-		FastMethod2Buffer<int, string> buffer = store.InstallMethod<int, string>(0);
+		FastMethod2Buffer<int, string> buffer = store.GetOrCreateBuffer<FastMethod2Buffer<int, string>>(0,
+			static f => new FastMethod2Buffer<int, string>(f));
 
 		int consumed = buffer.ConsumeAll();
 
@@ -271,7 +285,8 @@ public async Task FastMethod2Buffer_ConsumeAll_OnEmptyBuffer_ShouldReturnZeroWit
 	public async Task FastMethod2Buffer_ConsumeMatching_ShouldHonorAllMatchers()
 	{
 		FastMockInteractions store = new(1);
-		FastMethod2Buffer<int, string> buffer = store.InstallMethod<int, string>(0);
+		FastMethod2Buffer<int, string> buffer = store.GetOrCreateBuffer<FastMethod2Buffer<int, string>>(0,
+			static f => new FastMethod2Buffer<int, string>(f));
 
 		buffer.Append("Foo", 1, "a");
 		buffer.Append("Foo", 1, "b");
@@ -295,7 +310,8 @@ await That(buffer.ConsumeMatching(
 	public async Task FastMethod3Buffer_ConsumeAll_OnEmptyBuffer_ShouldReturnZeroWithoutThrowing()
 	{
 		FastMockInteractions store = new(1);
-		FastMethod3Buffer<int, string, bool> buffer = store.InstallMethod<int, string, bool>(0);
+		FastMethod3Buffer<int, string, bool> buffer = store.GetOrCreateBuffer<FastMethod3Buffer<int, string, bool>>(0,
+			static f => new FastMethod3Buffer<int, string, bool>(f));
 
 		int consumed = buffer.ConsumeAll();
 
@@ -306,7 +322,8 @@ public async Task FastMethod3Buffer_ConsumeAll_OnEmptyBuffer_ShouldReturnZeroWit
 	public async Task FastMethod3Buffer_ConsumeMatching_ShouldHonorAllMatchers()
 	{
 		FastMockInteractions store = new(1);
-		FastMethod3Buffer<int, string, bool> buffer = store.InstallMethod<int, string, bool>(0);
+		FastMethod3Buffer<int, string, bool> buffer = store.GetOrCreateBuffer<FastMethod3Buffer<int, string, bool>>(0,
+			static f => new FastMethod3Buffer<int, string, bool>(f));
 
 		buffer.Append("Foo", 1, "a", true);
 		buffer.Append("Foo", 2, "a", false);
@@ -335,7 +352,8 @@ public async Task FastMethod4Buffer_ConsumeAll_OnEmptyBuffer_ShouldReturnZeroWit
 	{
 		FastMockInteractions store = new(1);
 		FastMethod4Buffer<int, string, bool, double> buffer =
-			store.InstallMethod<int, string, bool, double>(0);
+			store.GetOrCreateBuffer<FastMethod4Buffer<int, string, bool, double>>(0,
+				static f => new FastMethod4Buffer<int, string, bool, double>(f));
 
 		int consumed = buffer.ConsumeAll();
 
@@ -347,7 +365,8 @@ public async Task FastMethod4Buffer_ConsumeMatching_ShouldHonorAllMatchers()
 	{
 		FastMockInteractions store = new(1);
 		FastMethod4Buffer<int, string, bool, double> buffer =
-			store.InstallMethod<int, string, bool, double>(0);
+			store.GetOrCreateBuffer<FastMethod4Buffer<int, string, bool, double>>(0,
+				static f => new FastMethod4Buffer<int, string, bool, double>(f));
 
 		buffer.Append("Foo", 1, "a", true, 1.0);
 		buffer.Append("Foo", 1, "b", true, 2.0);
@@ -384,12 +403,13 @@ await That(buffer.ConsumeMatching(
 	public async Task FastPropertyGetterBuffer_ConsumeMatching_ShouldReturnCount()
 	{
 		FastMockInteractions store = new(1);
-		FastPropertyGetterBuffer buffer = store.InstallPropertyGetter(0);
+		FastPropertyGetterBuffer buffer = store.GetOrCreateBuffer<FastPropertyGetterBuffer>(0,
+			static f => new FastPropertyGetterBuffer(f, new PropertyGetterAccess("Bar")));
 
 		await That(buffer.ConsumeMatching()).IsEqualTo(0);
 
-		buffer.Append("Bar");
-		buffer.Append("Bar");
+		buffer.Append();
+		buffer.Append();
 
 		await That(buffer.ConsumeMatching()).IsEqualTo(2);
 	}
@@ -398,7 +418,8 @@ public async Task FastPropertyGetterBuffer_ConsumeMatching_ShouldReturnCount()
 	public async Task FastPropertySetterBuffer_ConsumeMatching_ShouldHonorMatcher()
 	{
 		FastMockInteractions store = new(1);
-		FastPropertySetterBuffer<int> buffer = store.InstallPropertySetter<int>(0);
+		FastPropertySetterBuffer<int> buffer = store.GetOrCreateBuffer<FastPropertySetterBuffer<int>>(0,
+			static f => new FastPropertySetterBuffer<int>(f));
 
 		buffer.Append("Bar", 1);
 		buffer.Append("Bar", 2);
diff --git a/Tests/Mockolate.Internal.Tests/Interactions/FastMockInteractionsTests.cs b/Tests/Mockolate.Internal.Tests/Interactions/FastMockInteractionsTests.cs
index e4448297..fb548bfc 100644
--- a/Tests/Mockolate.Internal.Tests/Interactions/FastMockInteractionsTests.cs
+++ b/Tests/Mockolate.Internal.Tests/Interactions/FastMockInteractionsTests.cs
@@ -13,7 +13,7 @@ public class FastMockInteractionsTests
 	public async Task Append_ShouldRaiseInteractionAdded()
 	{
 		FastMockInteractions sut = new(1);
-		FastMethod0Buffer buffer = sut.InstallMethod(0);
+		FastMethod0Buffer buffer = InstallMethod(sut, 0);
 
 		int invocations = 0;
 		sut.InteractionAdded += Handler;
@@ -35,9 +35,10 @@ void Handler(object? sender, EventArgs e)
 	public async Task Buffers_ShouldExposeInstalledBuffersByMemberId()
 	{
 		FastMockInteractions sut = new(3);
-		FastMethod0Buffer method = sut.InstallMethod(0);
-		FastPropertyGetterBuffer getter = sut.InstallPropertyGetter(1);
-		FastEventBuffer subscribe = sut.InstallEventSubscribe(2);
+		FastMethod0Buffer method = InstallMethod(sut, 0);
+		FastPropertyGetterBuffer getter = InstallPropertyGetter(sut, 1);
+		FastEventBuffer subscribe = sut.GetOrCreateBuffer<FastEventBuffer>(2,
+			static f => new FastEventBuffer(f, FastEventBufferKind.Subscribe));
 
 		await That(sut.Buffers).HasCount(3);
 		await That(sut.Buffers[0]).IsSameAs(method);
@@ -109,7 +110,7 @@ public async Task Clear_FallbackPath_ShouldNotResurfaceOldRecordsAfterRefill()
 	public async Task Clear_ShouldFireOnClearing()
 	{
 		FastMockInteractions sut = new(1);
-		sut.InstallMethod(0);
+		InstallMethod(sut, 0);
 		int invocations = 0;
 		sut.OnClearing += Handler;
 
@@ -129,11 +130,11 @@ void Handler(object? sender, EventArgs e)
 	public async Task Clear_ShouldResetAllBuffersAndCount()
 	{
 		FastMockInteractions sut = new(2);
-		FastMethod0Buffer methodBuffer = sut.InstallMethod(0);
-		FastPropertyGetterBuffer getterBuffer = sut.InstallPropertyGetter(1);
+		FastMethod0Buffer methodBuffer = InstallMethod(sut, 0);
+		FastPropertyGetterBuffer getterBuffer = InstallPropertyGetter(sut, 1);
 
 		methodBuffer.Append("a");
-		getterBuffer.Append("b");
+		getterBuffer.Append();
 
 		sut.Clear();
 
@@ -147,18 +148,18 @@ public async Task Clear_ShouldResetAllBuffersAndCount()
 	public async Task Clear_ShouldResetPerBufferVerifiedTracking()
 	{
 		FastMockInteractions sut = new(2);
-		FastMethod1Buffer<int> methodBuffer = sut.InstallMethod<int>(0);
-		FastPropertyGetterBuffer getterBuffer = sut.InstallPropertyGetter(1);
+		FastMethod1Buffer<int> methodBuffer = InstallMethod<int>(sut, 0);
+		FastPropertyGetterBuffer getterBuffer = InstallPropertyGetter(sut, 1);
 
 		methodBuffer.Append("M", 1);
-		getterBuffer.Append("Prop");
+		getterBuffer.Append();
 		_ = methodBuffer.ConsumeMatching((IParameterMatch<int>)It.Is(1));
 		_ = getterBuffer.ConsumeMatching();
 
 		sut.Clear();
 
 		methodBuffer.Append("M", 2);
-		getterBuffer.Append("Prop");
+		getterBuffer.Append();
 
 		await That(sut.GetUnverifiedInteractions()).HasCount(2);
 	}
@@ -167,7 +168,7 @@ public async Task Clear_ShouldResetPerBufferVerifiedTracking()
 	public async Task Clear_ShouldResetVerifiedBookkeeping()
 	{
 		FastMockInteractions sut = new(1);
-		FastMethod0Buffer methodBuffer = sut.InstallMethod(0);
+		FastMethod0Buffer methodBuffer = InstallMethod(sut, 0);
 		methodBuffer.Append("first");
 		List<IInteraction> all = [..sut,];
 		((IMockInteractions)sut).Verified(all);
@@ -189,14 +190,14 @@ public async Task Clear_WithSharedSingletonInVerifiedSet_ShouldResurfaceItAsUnve
 		// removed, the verified set keeps the singleton across Clear, and a fresh post-Clear
 		// Append would surface as already-verified — masking the new interaction.
 		FastMockInteractions sut = new(1);
-		FastPropertyGetterBuffer buffer = sut.InstallPropertyGetter(0);
-		buffer.Append("P");
+		FastPropertyGetterBuffer buffer = InstallPropertyGetter(sut, 0);
+		buffer.Append();
 
 		List<IInteraction> all = [..sut,];
 		((IMockInteractions)sut).Verified(all);
 
 		sut.Clear();
-		buffer.Append("P");
+		buffer.Append();
 
 		IReadOnlyCollection<IInteraction> unverified = sut.GetUnverifiedInteractions();
 		await That(unverified).HasCount(1);
@@ -206,11 +207,11 @@ public async Task Clear_WithSharedSingletonInVerifiedSet_ShouldResurfaceItAsUnve
 	public async Task Count_ShouldReflectAppendsAcrossBuffers()
 	{
 		FastMockInteractions sut = new(2);
-		FastMethod0Buffer methodBuffer = sut.InstallMethod(0);
-		FastPropertyGetterBuffer getterBuffer = sut.InstallPropertyGetter(1);
+		FastMethod0Buffer methodBuffer = InstallMethod(sut, 0);
+		FastPropertyGetterBuffer getterBuffer = InstallPropertyGetter(sut, 1);
 
 		methodBuffer.Append("a");
-		getterBuffer.Append("b");
+		getterBuffer.Append();
 		methodBuffer.Append("c");
 
 		await That(sut.Count).IsEqualTo(3);
@@ -222,8 +223,9 @@ public async Task Count_ShouldReflectAppendsAcrossBuffers()
 	public async Task GetEnumerator_ShouldReturnInteractionsInRegistrationOrder()
 	{
 		FastMockInteractions sut = new(2);
-		FastMethod1Buffer<int> methodBuffer = sut.InstallMethod<int>(0);
-		FastPropertySetterBuffer<string> setterBuffer = sut.InstallPropertySetter<string>(1);
+		FastMethod1Buffer<int> methodBuffer = InstallMethod<int>(sut, 0);
+		FastPropertySetterBuffer<string> setterBuffer = sut.GetOrCreateBuffer<FastPropertySetterBuffer<string>>(1,
+			static f => new FastPropertySetterBuffer<string>(f));
 
 		methodBuffer.Append("Method", 1);
 		setterBuffer.Append("Property", "x");
@@ -347,8 +349,8 @@ public async Task GetUnverifiedInteractions_AcrossBuffersWithInterleavedAppends_
 		// sequence), the Sort step is what restores chronological order. Mutations that skip the
 		// Sort (`< 1`, `<= 1`, `!(>1)`) leave the snapshot grouped by buffer, not by Seq.
 		FastMockInteractions sut = new(2);
-		FastMethod1Buffer<int> bufA = sut.InstallMethod<int>(0);
-		FastMethod1Buffer<int> bufB = sut.InstallMethod<int>(1);
+		FastMethod1Buffer<int> bufA = InstallMethod<int>(sut, 0);
+		FastMethod1Buffer<int> bufB = InstallMethod<int>(sut, 1);
 
 		bufA.Append("A", 0);
 		bufB.Append("B", 1);
@@ -368,11 +370,11 @@ public async Task GetUnverifiedInteractions_AcrossBuffersWithInterleavedAppends_
 	public async Task GetUnverifiedInteractions_AcrossMultipleBuffers_ShouldUnionFastAndSlowVerifications()
 	{
 		FastMockInteractions sut = new(2);
-		FastMethod1Buffer<int> methodBuffer = sut.InstallMethod<int>(0);
-		FastPropertyGetterBuffer getterBuffer = sut.InstallPropertyGetter(1);
+		FastMethod1Buffer<int> methodBuffer = InstallMethod<int>(sut, 0);
+		FastPropertyGetterBuffer getterBuffer = InstallPropertyGetter(sut, 1);
 
 		methodBuffer.Append("M", 7);
-		getterBuffer.Append("Prop");
+		getterBuffer.Append();
 
 		_ = methodBuffer.ConsumeMatching((IParameterMatch<int>)It.Is(7));
 		_ = getterBuffer.ConsumeMatching();
@@ -384,7 +386,7 @@ public async Task GetUnverifiedInteractions_AcrossMultipleBuffers_ShouldUnionFas
 	public async Task GetUnverifiedInteractions_AfterMatcherLessConsumeMatching_ShouldDropMarkedSlots()
 	{
 		FastMockInteractions sut = new(1);
-		FastMethod0Buffer methodBuffer = sut.InstallMethod(0);
+		FastMethod0Buffer methodBuffer = InstallMethod(sut, 0);
 		methodBuffer.Append("first");
 		methodBuffer.Append("second");
 
@@ -403,7 +405,7 @@ public async Task GetUnverifiedInteractions_AfterMatcherLessConsumeMatching_Shou
 	public async Task GetUnverifiedInteractions_AfterTypedConsumeMatching_ShouldDropOnlyMatchedSlots()
 	{
 		FastMockInteractions sut = new(1);
-		FastMethod1Buffer<int> methodBuffer = sut.InstallMethod<int>(0);
+		FastMethod1Buffer<int> methodBuffer = InstallMethod<int>(sut, 0);
 		methodBuffer.Append("Dispense", 1);
 		methodBuffer.Append("Dispense", 2);
 
@@ -422,7 +424,7 @@ public async Task GetUnverifiedInteractions_AfterTypedConsumeMatching_ShouldDrop
 	public async Task GetUnverifiedInteractions_FastPathPlusSlowPath_ShouldFilterByBoth()
 	{
 		FastMockInteractions sut = new(1);
-		FastMethod1Buffer<int> methodBuffer = sut.InstallMethod<int>(0);
+		FastMethod1Buffer<int> methodBuffer = InstallMethod<int>(sut, 0);
 		methodBuffer.Append("M", 1);
 		methodBuffer.Append("M", 2);
 		methodBuffer.Append("M", 3);
@@ -441,7 +443,7 @@ public async Task GetUnverifiedInteractions_FastPathPlusSlowPath_ShouldFilterByB
 	public async Task GetUnverifiedInteractions_ShouldRespectVerifiedSet()
 	{
 		FastMockInteractions sut = new(1);
-		FastMethod0Buffer methodBuffer = sut.InstallMethod(0);
+		FastMethod0Buffer methodBuffer = InstallMethod(sut, 0);
 		methodBuffer.Append("first");
 		methodBuffer.Append("second");
 
@@ -462,7 +464,7 @@ public async Task GetUnverifiedInteractions_WhenNothingRecorded_ShouldReturnArra
 		// the block removed, the method falls through to `new IInteraction[unverified.Count]`
 		// and returns a freshly-allocated zero-length array instead of the shared singleton.
 		FastMockInteractions sut = new(1);
-		sut.InstallMethod(0);
+		InstallMethod(sut, 0);
 
 		IReadOnlyCollection<IInteraction> result = sut.GetUnverifiedInteractions();
 
@@ -473,7 +475,7 @@ public async Task GetUnverifiedInteractions_WhenNothingRecorded_ShouldReturnArra
 	public async Task GetUnverifiedInteractions_WhenNothingVerified_ShouldReturnEverything()
 	{
 		FastMockInteractions sut = new(1);
-		FastMethod0Buffer methodBuffer = sut.InstallMethod(0);
+		FastMethod0Buffer methodBuffer = InstallMethod(sut, 0);
 		methodBuffer.Append("first");
 
 		IReadOnlyCollection<IInteraction> unverified = sut.GetUnverifiedInteractions();
@@ -609,7 +611,7 @@ public async Task SkipInteractionRecording_ShouldReflectConstructionValue()
 	public async Task Verified_BeforeAnyAppend_OnSecondCallAddsToExistingSet()
 	{
 		FastMockInteractions sut = new(1);
-		FastMethod0Buffer buffer = sut.InstallMethod(0);
+		FastMethod0Buffer buffer = InstallMethod(sut, 0);
 
 		((IMockInteractions)sut).Verified([]);
 
@@ -627,7 +629,7 @@ public async Task Verified_OnSecondCallWithDifferentItems_PreservesPreviouslyVer
 		// plain `_verified = []`, the second call would reset the verified set, so the first
 		// call's entry would re-surface as "unverified".
 		FastMockInteractions sut = new(1);
-		FastMethod0Buffer buffer = sut.InstallMethod(0);
+		FastMethod0Buffer buffer = InstallMethod(sut, 0);
 		buffer.Append("first");
 		buffer.Append("second");
 		List<IInteraction> all = [..sut,];
@@ -642,7 +644,7 @@ public async Task Verified_OnSecondCallWithDifferentItems_PreservesPreviouslyVer
 	public async Task Verified_WithMultipleInteractions_AddsAllToInternalSet()
 	{
 		FastMockInteractions sut = new(1);
-		FastMethod0Buffer buffer = sut.InstallMethod(0);
+		FastMethod0Buffer buffer = InstallMethod(sut, 0);
 		buffer.Append("first");
 		buffer.Append("second");
 
@@ -652,13 +654,23 @@ public async Task Verified_WithMultipleInteractions_AddsAllToInternalSet()
 		await That(sut.GetUnverifiedInteractions()).IsEmpty();
 	}
 
+	private static FastMethod0Buffer InstallMethod(FastMockInteractions store, int memberId)
+		=> store.GetOrCreateBuffer<FastMethod0Buffer>(memberId, static f => new FastMethod0Buffer(f));
+
+	private static FastMethod1Buffer<T> InstallMethod<T>(FastMockInteractions store, int memberId)
+		=> store.GetOrCreateBuffer<FastMethod1Buffer<T>>(memberId, static f => new FastMethod1Buffer<T>(f));
+
+	private static FastPropertyGetterBuffer InstallPropertyGetter(FastMockInteractions store, int memberId)
+		=> store.GetOrCreateBuffer<FastPropertyGetterBuffer>(memberId,
+			static f => new FastPropertyGetterBuffer(f, new PropertyGetterAccess(string.Empty)));
+
 	public sealed class MethodBufferTests
 	{
 		[Fact]
 		public async Task Method0_BoxesAsMethodInvocation()
 		{
 			FastMockInteractions store = new(1);
-			FastMethod0Buffer buffer = store.InstallMethod(0);
+			FastMethod0Buffer buffer = InstallMethod(store, 0);
 
 			buffer.Append("Foo");
 
@@ -670,7 +682,7 @@ public async Task Method0_BoxesAsMethodInvocation()
 		public async Task Method1_BoxesAsMethodInvocationT1()
 		{
 			FastMockInteractions store = new(1);
-			FastMethod1Buffer<int> buffer = store.InstallMethod<int>(0);
+			FastMethod1Buffer<int> buffer = InstallMethod<int>(store, 0);
 
 			buffer.Append("Foo", 42);
 
@@ -683,7 +695,8 @@ public async Task Method1_BoxesAsMethodInvocationT1()
 		public async Task Method2_BoxesAsMethodInvocationT1T2()
 		{
 			FastMockInteractions store = new(1);
-			FastMethod2Buffer<int, string> buffer = store.InstallMethod<int, string>(0);
+			FastMethod2Buffer<int, string> buffer = store.GetOrCreateBuffer<FastMethod2Buffer<int, string>>(0,
+				static f => new FastMethod2Buffer<int, string>(f));
 
 			buffer.Append("Foo", 42, "bar");
 
@@ -696,7 +709,8 @@ public async Task Method2_BoxesAsMethodInvocationT1T2()
 		public async Task Method3_BoxesAsMethodInvocationT1T2T3()
 		{
 			FastMockInteractions store = new(1);
-			FastMethod3Buffer<int, string, bool> buffer = store.InstallMethod<int, string, bool>(0);
+			FastMethod3Buffer<int, string, bool> buffer = store.GetOrCreateBuffer<FastMethod3Buffer<int, string, bool>>(0,
+				static f => new FastMethod3Buffer<int, string, bool>(f));
 
 			buffer.Append("Foo", 1, "two", true);
 
@@ -711,7 +725,8 @@ public async Task Method4_BoxesAsMethodInvocationT1T2T3T4()
 		{
 			FastMockInteractions store = new(1);
 			FastMethod4Buffer<int, string, bool, double> buffer =
-				store.InstallMethod<int, string, bool, double>(0);
+				store.GetOrCreateBuffer<FastMethod4Buffer<int, string, bool, double>>(0,
+					static f => new FastMethod4Buffer<int, string, bool, double>(f));
 
 			buffer.Append("Foo", 1, "two", true, 3.14);
 
@@ -724,7 +739,7 @@ public async Task Method4_BoxesAsMethodInvocationT1T2T3T4()
 		public async Task ResizesAndPreservesOrder()
 		{
 			FastMockInteractions store = new(1);
-			FastMethod1Buffer<int> buffer = store.InstallMethod<int>(0);
+			FastMethod1Buffer<int> buffer = InstallMethod<int>(store, 0);
 
 			for (int i = 0; i < 100; i++)
 			{
@@ -746,9 +761,10 @@ public sealed class PropertyBufferTests
 		public async Task Getter_BoxesAsPropertyGetterAccess()
 		{
 			FastMockInteractions store = new(1);
-			FastPropertyGetterBuffer buffer = store.InstallPropertyGetter(0);
+			FastPropertyGetterBuffer buffer = store.GetOrCreateBuffer<FastPropertyGetterBuffer, PropertyGetterAccess>(
+				0, static (f, a) => new FastPropertyGetterBuffer(f, a), new PropertyGetterAccess("Foo"));
 
-			buffer.Append("Foo");
+			buffer.Append();
 
 			PropertyGetterAccess boxed = (PropertyGetterAccess)store.Single();
 			await That(boxed.Name).IsEqualTo("Foo");
@@ -758,7 +774,8 @@ public async Task Getter_BoxesAsPropertyGetterAccess()
 		public async Task Setter_BoxesAsPropertySetterAccessT()
 		{
 			FastMockInteractions store = new(1);
-			FastPropertySetterBuffer<string> buffer = store.InstallPropertySetter<string>(0);
+			FastPropertySetterBuffer<string> buffer = store.GetOrCreateBuffer<FastPropertySetterBuffer<string>>(0,
+				static f => new FastPropertySetterBuffer<string>(f));
 
 			buffer.Append("Foo", "value");
 
@@ -774,7 +791,8 @@ public sealed class IndexerBufferTests
 		public async Task Getter1_BoxesAsIndexerGetterAccess()
 		{
 			FastMockInteractions store = new(1);
-			FastIndexerGetterBuffer<string> buffer = store.InstallIndexerGetter<string>(0);
+			FastIndexerGetterBuffer<string> buffer = store.GetOrCreateBuffer<FastIndexerGetterBuffer<string>>(0,
+				static f => new FastIndexerGetterBuffer<string>(f));
 
 			buffer.Append("k");
 
@@ -786,7 +804,8 @@ public async Task Getter1_BoxesAsIndexerGetterAccess()
 		public async Task Getter2_BoxesAsIndexerGetterAccess()
 		{
 			FastMockInteractions store = new(1);
-			FastIndexerGetterBuffer<string, int> buffer = store.InstallIndexerGetter<string, int>(0);
+			FastIndexerGetterBuffer<string, int> buffer = store.GetOrCreateBuffer<FastIndexerGetterBuffer<string, int>>(0,
+				static f => new FastIndexerGetterBuffer<string, int>(f));
 
 			buffer.Append("k", 1);
 
@@ -799,7 +818,8 @@ public async Task Getter2_BoxesAsIndexerGetterAccess()
 		public async Task Setter1_BoxesAsIndexerSetterAccess()
 		{
 			FastMockInteractions store = new(1);
-			FastIndexerSetterBuffer<string, bool> buffer = store.InstallIndexerSetter<string, bool>(0);
+			FastIndexerSetterBuffer<string, bool> buffer = store.GetOrCreateBuffer<FastIndexerSetterBuffer<string, bool>>(0,
+				static f => new FastIndexerSetterBuffer<string, bool>(f));
 
 			buffer.Append("k", true);
 
@@ -813,7 +833,8 @@ public async Task Setter2_BoxesAsIndexerSetterAccess()
 		{
 			FastMockInteractions store = new(1);
 			FastIndexerSetterBuffer<string, int, bool> buffer =
-				store.InstallIndexerSetter<string, int, bool>(0);
+				store.GetOrCreateBuffer<FastIndexerSetterBuffer<string, int, bool>>(0,
+					static f => new FastIndexerSetterBuffer<string, int, bool>(f));
 
 			buffer.Append("k", 7, true);
 
@@ -828,7 +849,8 @@ public sealed class EventBufferTests
 		public async Task Subscribe_BoxesAsEventSubscription()
 		{
 			FastMockInteractions store = new(1);
-			FastEventBuffer buffer = store.InstallEventSubscribe(0);
+			FastEventBuffer buffer = store.GetOrCreateBuffer<FastEventBuffer>(0,
+				static f => new FastEventBuffer(f, FastEventBufferKind.Subscribe));
 			MethodInfo method = typeof(EventBufferTests).GetMethod(nameof(Subscribe_BoxesAsEventSubscription))!;
 
 			buffer.Append("E", this, method);
@@ -843,7 +865,8 @@ public async Task Subscribe_BoxesAsEventSubscription()
 		public async Task Unsubscribe_BoxesAsEventUnsubscription()
 		{
 			FastMockInteractions store = new(1);
-			FastEventBuffer buffer = store.InstallEventUnsubscribe(0);
+			FastEventBuffer buffer = store.GetOrCreateBuffer<FastEventBuffer>(0,
+				static f => new FastEventBuffer(f, FastEventBufferKind.Unsubscribe));
 			MethodInfo method = typeof(EventBufferTests).GetMethod(nameof(Unsubscribe_BoxesAsEventUnsubscription))!;
 
 			buffer.Append("E", null, method);
@@ -864,7 +887,7 @@ public async Task ConcurrentAppendsAcrossMembers_ShouldPreserveTotalCount()
 			FastMethod1Buffer<int>[] buffers = new FastMethod1Buffer<int>[threads];
 			for (int t = 0; t < threads; t++)
 			{
-				buffers[t] = store.InstallMethod<int>(t);
+				buffers[t] = InstallMethod<int>(store, t);
 			}
 
 			using ManualResetEventSlim start = new(false);
diff --git a/Tests/Mockolate.Internal.Tests/Interactions/FastPropertyBufferTests.cs b/Tests/Mockolate.Internal.Tests/Interactions/FastPropertyBufferTests.cs
index c4569366..71d810e5 100644
--- a/Tests/Mockolate.Internal.Tests/Interactions/FastPropertyBufferTests.cs
+++ b/Tests/Mockolate.Internal.Tests/Interactions/FastPropertyBufferTests.cs
@@ -70,9 +70,7 @@ public async Task SkipInteractionRecording_DoesNotAppendToBuffer()
 
 		FastMockInteractions fast = (FastMockInteractions)((IMock)sut).MockRegistry.Interactions;
 		int getterId = Mock.FastPropertyBufferTests_IFastPropertyService.MemberId_Counter_Get;
-		FastPropertyGetterBuffer? buffer = fast.Buffers[getterId] as FastPropertyGetterBuffer;
-		await That(buffer).IsNotNull();
-		await That(buffer!.Count).IsEqualTo(0);
+		await That(fast.Buffers[getterId]).IsNull();
 		await That(fast.Count).IsEqualTo(0);
 	}
 
diff --git a/Tests/Mockolate.Internal.Tests/Registry/MockRegistrySetupSnapshotTests.cs b/Tests/Mockolate.Internal.Tests/Registry/MockRegistrySetupSnapshotTests.cs
index 83158df7..1179dc97 100644
--- a/Tests/Mockolate.Internal.Tests/Registry/MockRegistrySetupSnapshotTests.cs
+++ b/Tests/Mockolate.Internal.Tests/Registry/MockRegistrySetupSnapshotTests.cs
@@ -153,7 +153,7 @@ public async Task PublishPropertyToMemberIdBucket_WithDefaultThenUserSetup_Retai
 			registry.SetupProperty(1, new PropertySetup.Default<int>("P1", 0));
 			registry.SetupProperty(1, userSetup);
 
-			int observed = registry.GetPropertyFast(1, "P1", _ => -1);
+			int observed = registry.GetPropertyFast(1, new PropertyGetterAccess("P1"), _ => -1);
 			await That(observed).IsEqualTo(99);
 		}
 
@@ -181,7 +181,7 @@ public async Task PublishPropertyToMemberIdBucket_WithUserThenDefaultSetup_Retai
 			registry.SetupProperty(1, userSetup);
 			registry.SetupProperty(1, new PropertySetup.Default<int>("P1", 0));
 
-			int observed = registry.GetPropertyFast(1, "P1", _ => -1);
+			int observed = registry.GetPropertyFast(1, new PropertyGetterAccess("P1"), _ => -1);
 			await That(observed).IsEqualTo(99);
 		}
 
@@ -250,9 +250,9 @@ public async Task SetupProperty_WithIncreasingMemberIds_GrowsTableLazily()
 			registry.SetupProperty(7, setup7);
 			registry.SetupProperty(3, setup3);
 
-			await That(registry.GetPropertyFast(0, "P0", _ => -1)).IsEqualTo(10);
-			await That(registry.GetPropertyFast(7, "P7", _ => -1)).IsEqualTo(70);
-			await That(registry.GetPropertyFast(3, "P3", _ => -1)).IsEqualTo(30);
+			await That(registry.GetPropertyFast(0, new PropertyGetterAccess("P0"), _ => -1)).IsEqualTo(10);
+			await That(registry.GetPropertyFast(7, new PropertyGetterAccess("P7"), _ => -1)).IsEqualTo(70);
+			await That(registry.GetPropertyFast(3, new PropertyGetterAccess("P3"), _ => -1)).IsEqualTo(30);
 		}
 
 		[Fact]
@@ -279,7 +279,7 @@ public async Task SetupProperty_WithMemberId_PublishesToSnapshot()
 
 			registry.SetupProperty(5, setup);
 
-			int observed = registry.GetPropertyFast(5, "P5", _ => -1);
+			int observed = registry.GetPropertyFast(5, new PropertyGetterAccess("P5"), _ => -1);
 			await That(observed).IsEqualTo(50);
 		}
 
@@ -319,7 +319,7 @@ public async Task SetupProperty_WithMemberIdAndDefaultScenario_PublishesToSnapsh
 
 			registry.SetupProperty(5, "", setup);
 
-			int observed = registry.GetPropertyFast(5, "P5", _ => -1);
+			int observed = registry.GetPropertyFast(5, new PropertyGetterAccess("P5"), _ => -1);
 			await That(observed).IsEqualTo(50);
 		}
 
@@ -345,7 +345,7 @@ public async Task SetupProperty_WithMemberIdAndNamedScenario_DoesNotPublishToSna
 
 			registry.SetupProperty(5, "s1", setup);
 
-			int observed = registry.GetPropertyFast(5, "P5", _ => -1);
+			int observed = registry.GetPropertyFast(5, new PropertyGetterAccess("P5"), _ => -1);
 			await That(observed).IsEqualTo(-1);
 		}
 
@@ -387,7 +387,7 @@ public async Task SetupProperty_WithSameMemberIdTwice_RetainsLatestUserSetup()
 			registry.SetupProperty(2, setupA);
 			registry.SetupProperty(2, setupB);
 
-			int observed = registry.GetPropertyFast(2, "P2", _ => -1);
+			int observed = registry.GetPropertyFast(2, new PropertyGetterAccess("P2"), _ => -1);
 			await That(observed).IsEqualTo(99);
 		}
 	}
diff --git a/Tests/Mockolate.Internal.Tests/Registry/MockRegistryTests.cs b/Tests/Mockolate.Internal.Tests/Registry/MockRegistryTests.cs
index eba1ec3c..83cd7665 100644
--- a/Tests/Mockolate.Internal.Tests/Registry/MockRegistryTests.cs
+++ b/Tests/Mockolate.Internal.Tests/Registry/MockRegistryTests.cs
@@ -557,7 +557,7 @@ public async Task WithActiveScenario_ShouldAlwaysTakeColdPath()
 			registry.SetupProperty(2, "myScenario", scenarioSetup);
 
 			registry.TransitionTo("myScenario");
-			int result = registry.GetPropertyFast(2, "P", _ => 0);
+			int result = registry.GetPropertyFast(2, new PropertyGetterAccess("P"), _ => 0);
 
 			await That(result).IsEqualTo(99);
 		}
@@ -577,7 +577,7 @@ int Base()
 				return 99;
 			}
 
-			int result = registry.GetPropertyFast(2, "P", _ => 7, Base);
+			int result = registry.GetPropertyFast(2, new PropertyGetterAccess("P"), _ => 7, Base);
 
 			await That(baseInvocations).IsEqualTo(1);
 			await That(result).IsEqualTo(99);
@@ -594,7 +594,7 @@ public async Task WithNullSnapshotAtMemberIdSlot_ShouldFallBackToColdPathWithout
 			unrelatedSetup.InitializeWith(99);
 			registry.SetupProperty(5, unrelatedSetup);
 
-			int result = registry.GetPropertyFast(0, "P", _ => 7);
+			int result = registry.GetPropertyFast(0, new PropertyGetterAccess("P"), _ => 7);
 
 			await That(result).IsEqualTo(7);
 		}
@@ -604,7 +604,7 @@ public async Task WithoutSnapshotSetup_ShouldFallBackToColdPath()
 		{
 			MockRegistry registry = new(MockBehavior.Default, new FastMockInteractions(0));
 
-			int result = registry.GetPropertyFast(0, "P", _ => 7);
+			int result = registry.GetPropertyFast(0, new PropertyGetterAccess("P"), _ => 7);
 
 			await That(result).IsEqualTo(7);
 		}
@@ -625,8 +625,8 @@ int Generator(MockBehavior _)
 				return -1;
 			}
 
-			int first = registry.GetPropertyFast(2, "P", Generator);
-			int second = registry.GetPropertyFast(2, "P", Generator);
+			int first = registry.GetPropertyFast(2, new PropertyGetterAccess("P"), Generator);
+			int second = registry.GetPropertyFast(2, new PropertyGetterAccess("P"), Generator);
 
 			await That(first).IsEqualTo(42);
 			await That(second).IsEqualTo(42);
@@ -711,7 +711,7 @@ public async Task WithSnapshotSetup_ShouldInvokeSetterAndStoreValue()
 			bool skipBase = registry.SetPropertyFast(2, 3, "P", 42);
 
 			await That(skipBase).IsFalse();
-			int after = registry.GetPropertyFast(2, "P", _ => -1);
+			int after = registry.GetPropertyFast(2, new PropertyGetterAccess("P"), _ => -1);
 			await That(after).IsEqualTo(42);
 		}
 	}
@@ -912,7 +912,7 @@ public async Task GetPropertyFast_WhenSnapshotTableHasNullEntryAtMemberId_Should
 			snapshotAtFive.InitializeWith(50);
 			registry.SetupProperty(5, snapshotAtFive);
 
-			int result = registry.GetPropertyFast(2, "P", _ => 7);
+			int result = registry.GetPropertyFast(2, new PropertyGetterAccess("P"), _ => 7);
 
 			await That(result).IsEqualTo(7);
 		}
@@ -941,7 +941,7 @@ public async Task SetPropertyFast_WithActiveScenario_ShouldUseColdPathAndWriteTo
 			registry.TransitionTo("myScenario");
 			registry.SetPropertyFast(2, 3, "P", 42);
 
-			int result = registry.GetPropertyFast(2, "P", _ => -1);
+			int result = registry.GetPropertyFast(2, new PropertyGetterAccess("P"), _ => -1);
 
 			await That(result).IsEqualTo(42);
 		}
@@ -986,7 +986,8 @@ public async Task WithSharedAccessSingleton_AndMatchingFastBuffer_ShouldAppendTo
 		{
 			FastMockInteractions store = new(1);
 			PropertyGetterAccess access = new("P");
-			FastPropertyGetterBuffer buffer = store.InstallPropertyGetter(0, access);
+			FastPropertyGetterBuffer buffer = store.GetOrCreateBuffer<FastPropertyGetterBuffer, PropertyGetterAccess>(
+				0, static (f, a) => new FastPropertyGetterBuffer(f, a), access);
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			int result = registry.GetPropertyFast(0, access, _ => 7);
@@ -1012,10 +1013,12 @@ public async Task WithSharedAccessSingleton_WithoutMatchingBuffer_ShouldRegister
 		public async Task WithStringName_AndMatchingFastBuffer_ShouldAppendToBuffer()
 		{
 			FastMockInteractions store = new(1);
-			FastPropertyGetterBuffer buffer = store.InstallPropertyGetter(0);
+			PropertyGetterAccess access = new("P");
+			FastPropertyGetterBuffer buffer = store.GetOrCreateBuffer<FastPropertyGetterBuffer, PropertyGetterAccess>(
+				0, static (f, a) => new FastPropertyGetterBuffer(f, a), access);
 			MockRegistry registry = new(MockBehavior.Default, store);
 
-			int result = registry.GetPropertyFast(0, "P", _ => 7);
+			int result = registry.GetPropertyFast(0, access, _ => 7);
 
 			await That(buffer.Count).IsEqualTo(1);
 			await That(result).IsEqualTo(7);
@@ -1027,7 +1030,7 @@ public async Task WithStringName_AtBufferLengthBoundary_ShouldFallBackWithoutThr
 			FastMockInteractions store = new(1);
 			MockRegistry registry = new(MockBehavior.Default, store);
 
-			int result = registry.GetPropertyFast(1, "P", _ => 7);
+			int result = registry.GetPropertyFast(1, new PropertyGetterAccess("P"), _ => 7);
 
 			await That(result).IsEqualTo(7);
 			await That(registry.Interactions.Count).IsEqualTo(1);
@@ -1041,7 +1044,7 @@ public async Task WithStringName_AtTableLengthBoundary_ShouldFallToColdPathWitho
 			snapshot.InitializeWith(42);
 			registry.SetupProperty(0, snapshot);
 
-			int result = registry.GetPropertyFast(1, "Q", _ => 7);
+			int result = registry.GetPropertyFast(1, new PropertyGetterAccess("Q"), _ => 7);
 
 			await That(result).IsEqualTo(7);
 		}
@@ -1051,10 +1054,12 @@ public async Task WithStringName_WhenBehaviorSkipsInteractionRecording_ShouldNot
 		{
 			MockBehavior behavior = MockBehavior.Default.SkippingInteractionRecording();
 			FastMockInteractions store = new(1, behavior.SkipInteractionRecording);
-			FastPropertyGetterBuffer buffer = store.InstallPropertyGetter(0);
+			PropertyGetterAccess access = new("P");
+			FastPropertyGetterBuffer buffer = store.GetOrCreateBuffer<FastPropertyGetterBuffer, PropertyGetterAccess>(
+				0, static (f, a) => new FastPropertyGetterBuffer(f, a), access);
 			MockRegistry registry = new(behavior, store);
 
-			registry.GetPropertyFast(0, "P", _ => 7);
+			registry.GetPropertyFast(0, access, _ => 7);
 
 			await That(buffer.Count).IsEqualTo(0);
 			await That(registry.Interactions.Count).IsEqualTo(0);
@@ -1066,7 +1071,7 @@ public async Task WithStringName_WithoutMatchingBuffer_ShouldFallBackToRegisterP
 			FastMockInteractions store = new(0);
 			MockRegistry registry = new(MockBehavior.Default, store);
 
-			registry.GetPropertyFast(0, "P", _ => 7);
+			registry.GetPropertyFast(0, new PropertyGetterAccess("P"), _ => 7);
 
 			IInteraction recorded = registry.Interactions.Single();
 			await That(recorded).IsExactly<PropertyGetterAccess>()
diff --git a/Tests/Mockolate.Internal.Tests/Verify/CountSourceTests.cs b/Tests/Mockolate.Internal.Tests/Verify/CountSourceTests.cs
index 8aa8d720..66da8d28 100644
--- a/Tests/Mockolate.Internal.Tests/Verify/CountSourceTests.cs
+++ b/Tests/Mockolate.Internal.Tests/Verify/CountSourceTests.cs
@@ -11,7 +11,8 @@ public class CountSourceTests
 	public async Task EventCountSource_Subscribe_Count_IsExercised()
 	{
 		FastMockInteractions store = new(1);
-		FastEventBuffer buffer = store.InstallEventSubscribe(0);
+		FastEventBuffer buffer = store.GetOrCreateBuffer<FastEventBuffer>(0,
+			static f => new FastEventBuffer(f, FastEventBufferKind.Subscribe));
 		MockRegistry registry = new(MockBehavior.Default, store);
 
 		MethodInfo m = typeof(CountSourceTests).GetMethod(
@@ -28,7 +29,8 @@ public async Task EventCountSource_Subscribe_Count_IsExercised()
 	public async Task EventCountSource_Unsubscribe_Count_IsExercised()
 	{
 		FastMockInteractions store = new(1);
-		FastEventBuffer buffer = store.InstallEventUnsubscribe(0);
+		FastEventBuffer buffer = store.GetOrCreateBuffer<FastEventBuffer>(0,
+			static f => new FastEventBuffer(f, FastEventBufferKind.Unsubscribe));
 		MockRegistry registry = new(MockBehavior.Default, store);
 
 		MethodInfo m = typeof(CountSourceTests).GetMethod(
@@ -46,7 +48,8 @@ public async Task EventCountSource_Unsubscribe_Count_IsExercised()
 	public async Task IndexerGetter1_FastPath_Count_IsExercised()
 	{
 		FastMockInteractions store = new(1);
-		FastIndexerGetterBuffer<int> buffer = store.InstallIndexerGetter<int>(0);
+		FastIndexerGetterBuffer<int> buffer = store.GetOrCreateBuffer<FastIndexerGetterBuffer<int>>(0,
+			static f => new FastIndexerGetterBuffer<int>(f));
 		MockRegistry registry = new(MockBehavior.Default, store);
 
 		buffer.Append(5);
@@ -63,7 +66,8 @@ public async Task IndexerGetter1_FastPath_Count_IsExercised()
 	public async Task IndexerGetter2_FastPath_Count_IsExercised()
 	{
 		FastMockInteractions store = new(1);
-		FastIndexerGetterBuffer<int, string> buffer = store.InstallIndexerGetter<int, string>(0);
+		FastIndexerGetterBuffer<int, string> buffer = store.GetOrCreateBuffer<FastIndexerGetterBuffer<int, string>>(0,
+			static f => new FastIndexerGetterBuffer<int, string>(f));
 		MockRegistry registry = new(MockBehavior.Default, store);
 
 		buffer.Append(5, "a");
@@ -83,7 +87,8 @@ public async Task IndexerGetter3_FastPath_Count_IsExercised()
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerGetterBuffer<int, string, bool> buffer =
-			store.InstallIndexerGetter<int, string, bool>(0);
+			store.GetOrCreateBuffer<FastIndexerGetterBuffer<int, string, bool>>(0,
+				static f => new FastIndexerGetterBuffer<int, string, bool>(f));
 		MockRegistry registry = new(MockBehavior.Default, store);
 
 		buffer.Append(5, "a", true);
@@ -104,7 +109,8 @@ public async Task IndexerGetter4_FastPath_Count_IsExercised()
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerGetterBuffer<int, string, bool, double> buffer =
-			store.InstallIndexerGetter<int, string, bool, double>(0);
+			store.GetOrCreateBuffer<FastIndexerGetterBuffer<int, string, bool, double>>(0,
+				static f => new FastIndexerGetterBuffer<int, string, bool, double>(f));
 		MockRegistry registry = new(MockBehavior.Default, store);
 
 		buffer.Append(5, "a", true, 1.5);
@@ -125,7 +131,8 @@ public async Task IndexerGetter4_FastPath_Count_IsExercised()
 	public async Task IndexerSetter1_FastPath_Count_IsExercised()
 	{
 		FastMockInteractions store = new(1);
-		FastIndexerSetterBuffer<int, string> buffer = store.InstallIndexerSetter<int, string>(0);
+		FastIndexerSetterBuffer<int, string> buffer = store.GetOrCreateBuffer<FastIndexerSetterBuffer<int, string>>(0,
+			static f => new FastIndexerSetterBuffer<int, string>(f));
 		MockRegistry registry = new(MockBehavior.Default, store);
 
 		buffer.Append(5, "v");
@@ -145,7 +152,8 @@ public async Task IndexerSetter2_FastPath_Count_IsExercised()
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerSetterBuffer<int, string, double> buffer =
-			store.InstallIndexerSetter<int, string, double>(0);
+			store.GetOrCreateBuffer<FastIndexerSetterBuffer<int, string, double>>(0,
+				static f => new FastIndexerSetterBuffer<int, string, double>(f));
 		MockRegistry registry = new(MockBehavior.Default, store);
 
 		buffer.Append(5, "a", 1.5);
@@ -166,7 +174,8 @@ public async Task IndexerSetter3_FastPath_Count_IsExercised()
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerSetterBuffer<int, string, bool, double> buffer =
-			store.InstallIndexerSetter<int, string, bool, double>(0);
+			store.GetOrCreateBuffer<FastIndexerSetterBuffer<int, string, bool, double>>(0,
+				static f => new FastIndexerSetterBuffer<int, string, bool, double>(f));
 		MockRegistry registry = new(MockBehavior.Default, store);
 
 		buffer.Append(5, "a", true, 1.5);
@@ -188,7 +197,8 @@ public async Task IndexerSetter4_FastPath_Count_IsExercised()
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerSetterBuffer<int, string, bool, double, long> buffer =
-			store.InstallIndexerSetter<int, string, bool, double, long>(0);
+			store.GetOrCreateBuffer<FastIndexerSetterBuffer<int, string, bool, double, long>>(0,
+				static f => new FastIndexerSetterBuffer<int, string, bool, double, long>(f));
 		MockRegistry registry = new(MockBehavior.Default, store);
 
 		buffer.Append(5, "a", true, 1.5, 100L);
@@ -210,7 +220,8 @@ public async Task IndexerSetter4_FastPath_Count_IsExercised()
 	public async Task Method0_FastPath_Count_AndCountAll_AreExercised()
 	{
 		FastMockInteractions store = new(1);
-		FastMethod0Buffer buffer = store.InstallMethod(0);
+		FastMethod0Buffer buffer = store.GetOrCreateBuffer<FastMethod0Buffer>(0,
+			static f => new FastMethod0Buffer(f));
 		MockRegistry registry = new(MockBehavior.Default, store);
 
 		buffer.Append("Foo");
@@ -227,7 +238,8 @@ public async Task Method0_FastPath_Count_AndCountAll_AreExercised()
 	public async Task Method1_FastPath_Count_AndCountAll_AreExercised()
 	{
 		FastMockInteractions store = new(1);
-		FastMethod1Buffer<int> buffer = store.InstallMethod<int>(0);
+		FastMethod1Buffer<int> buffer = store.GetOrCreateBuffer<FastMethod1Buffer<int>>(0,
+			static f => new FastMethod1Buffer<int>(f));
 		MockRegistry registry = new(MockBehavior.Default, store);
 
 		buffer.Append("Foo", 1);
@@ -245,7 +257,8 @@ public async Task Method1_FastPath_Count_AndCountAll_AreExercised()
 	public async Task Method2_FastPath_Count_AndCountAll_AreExercised()
 	{
 		FastMockInteractions store = new(1);
-		FastMethod2Buffer<int, string> buffer = store.InstallMethod<int, string>(0);
+		FastMethod2Buffer<int, string> buffer = store.GetOrCreateBuffer<FastMethod2Buffer<int, string>>(0,
+			static f => new FastMethod2Buffer<int, string>(f));
 		MockRegistry registry = new(MockBehavior.Default, store);
 
 		buffer.Append("Foo", 1, "a");
@@ -265,7 +278,8 @@ public async Task Method2_FastPath_Count_AndCountAll_AreExercised()
 	public async Task Method3_FastPath_Count_AndCountAll_AreExercised()
 	{
 		FastMockInteractions store = new(1);
-		FastMethod3Buffer<int, string, bool> buffer = store.InstallMethod<int, string, bool>(0);
+		FastMethod3Buffer<int, string, bool> buffer = store.GetOrCreateBuffer<FastMethod3Buffer<int, string, bool>>(0,
+			static f => new FastMethod3Buffer<int, string, bool>(f));
 		MockRegistry registry = new(MockBehavior.Default, store);
 
 		buffer.Append("Foo", 1, "a", true);
@@ -291,7 +305,8 @@ public async Task Method4_FastPath_Count_AndCountAll_AreExercised()
 	{
 		FastMockInteractions store = new(1);
 		FastMethod4Buffer<int, string, bool, double> buffer =
-			store.InstallMethod<int, string, bool, double>(0);
+			store.GetOrCreateBuffer<FastMethod4Buffer<int, string, bool, double>>(0,
+				static f => new FastMethod4Buffer<int, string, bool, double>(f));
 		MockRegistry registry = new(MockBehavior.Default, store);
 
 		buffer.Append("Foo", 1, "a", true, 1.5);
@@ -317,11 +332,12 @@ public async Task Method4_FastPath_Count_AndCountAll_AreExercised()
 	public async Task PropertyGetter_FastPath_Count_IsExercised()
 	{
 		FastMockInteractions store = new(1);
-		FastPropertyGetterBuffer buffer = store.InstallPropertyGetter(0);
+		FastPropertyGetterBuffer buffer = store.GetOrCreateBuffer<FastPropertyGetterBuffer>(0,
+			static f => new FastPropertyGetterBuffer(f, new PropertyGetterAccess("P")));
 		MockRegistry registry = new(MockBehavior.Default, store);
 
-		buffer.Append("P");
-		buffer.Append("P");
+		buffer.Append();
+		buffer.Append();
 
 		registry.VerifyPropertyTyped(new object(), 0, "P").Twice();
 
@@ -332,7 +348,8 @@ public async Task PropertyGetter_FastPath_Count_IsExercised()
 	public async Task PropertySetter_FastPath_Count_IsExercised()
 	{
 		FastMockInteractions store = new(1);
-		FastPropertySetterBuffer<int> buffer = store.InstallPropertySetter<int>(0);
+		FastPropertySetterBuffer<int> buffer = store.GetOrCreateBuffer<FastPropertySetterBuffer<int>>(0,
+			static f => new FastPropertySetterBuffer<int>(f));
 		MockRegistry registry = new(MockBehavior.Default, store);
 
 		buffer.Append("P", 1);
diff --git a/Tests/Mockolate.Internal.Tests/Verify/MethodCountSourcesTests.cs b/Tests/Mockolate.Internal.Tests/Verify/MethodCountSourcesTests.cs
index 9431e01f..8f7d5b93 100644
--- a/Tests/Mockolate.Internal.Tests/Verify/MethodCountSourcesTests.cs
+++ b/Tests/Mockolate.Internal.Tests/Verify/MethodCountSourcesTests.cs
@@ -12,7 +12,8 @@ public class MethodCountSourcesTests
 	public async Task EventCountSource_ShouldReturnSubscribeCount()
 	{
 		FastMockInteractions store = new(1);
-		FastEventBuffer buffer = store.InstallEventSubscribe(0);
+		FastEventBuffer buffer = store.GetOrCreateBuffer<FastEventBuffer>(0,
+			static f => new FastEventBuffer(f, FastEventBufferKind.Subscribe));
 		MethodInfo handler = typeof(MethodCountSourcesTests).GetMethod(
 			nameof(EventCountSource_ShouldReturnSubscribeCount))!;
 		buffer.Append("E", null, handler);
@@ -27,7 +28,8 @@ public async Task EventCountSource_ShouldReturnSubscribeCount()
 	public async Task IndexerGetter1CountSource_ShouldHonorKeyMatcher()
 	{
 		FastMockInteractions store = new(1);
-		FastIndexerGetterBuffer<int> buffer = store.InstallIndexerGetter<int>(0);
+		FastIndexerGetterBuffer<int> buffer = store.GetOrCreateBuffer<FastIndexerGetterBuffer<int>>(0,
+			static f => new FastIndexerGetterBuffer<int>(f));
 		buffer.Append(1);
 		buffer.Append(2);
 		buffer.Append(1);
@@ -41,7 +43,8 @@ public async Task IndexerGetter1CountSource_ShouldHonorKeyMatcher()
 	public async Task IndexerGetter2CountSource_ShouldHonorBothMatchers()
 	{
 		FastMockInteractions store = new(1);
-		FastIndexerGetterBuffer<int, string> buffer = store.InstallIndexerGetter<int, string>(0);
+		FastIndexerGetterBuffer<int, string> buffer = store.GetOrCreateBuffer<FastIndexerGetterBuffer<int, string>>(0,
+			static f => new FastIndexerGetterBuffer<int, string>(f));
 		buffer.Append(1, "a");
 		buffer.Append(2, "a");
 		buffer.Append(1, "b");
@@ -58,7 +61,8 @@ public async Task IndexerGetter3CountSource_ShouldHonorAllThreeMatchers()
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerGetterBuffer<int, string, bool> buffer =
-			store.InstallIndexerGetter<int, string, bool>(0);
+			store.GetOrCreateBuffer<FastIndexerGetterBuffer<int, string, bool>>(0,
+				static f => new FastIndexerGetterBuffer<int, string, bool>(f));
 		buffer.Append(1, "a", true);
 		buffer.Append(1, "a", false);
 		buffer.Append(2, "a", true);
@@ -76,7 +80,8 @@ public async Task IndexerGetter4CountSource_ShouldHonorAllFourMatchers()
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerGetterBuffer<int, string, bool, double> buffer =
-			store.InstallIndexerGetter<int, string, bool, double>(0);
+			store.GetOrCreateBuffer<FastIndexerGetterBuffer<int, string, bool, double>>(0,
+				static f => new FastIndexerGetterBuffer<int, string, bool, double>(f));
 		buffer.Append(1, "a", true, 0.5);
 		buffer.Append(1, "a", true, 1.5);
 		buffer.Append(2, "a", true, 0.5);
@@ -94,7 +99,8 @@ public async Task IndexerGetter4CountSource_ShouldHonorAllFourMatchers()
 	public async Task IndexerSetter1CountSource_ShouldHonorKeyAndValueMatchers()
 	{
 		FastMockInteractions store = new(1);
-		FastIndexerSetterBuffer<int, string> buffer = store.InstallIndexerSetter<int, string>(0);
+		FastIndexerSetterBuffer<int, string> buffer = store.GetOrCreateBuffer<FastIndexerSetterBuffer<int, string>>(0,
+			static f => new FastIndexerSetterBuffer<int, string>(f));
 		buffer.Append(1, "a");
 		buffer.Append(1, "b");
 		buffer.Append(2, "a");
@@ -111,7 +117,8 @@ public async Task IndexerSetter2CountSource_ShouldHonorAllMatchers()
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerSetterBuffer<int, string, bool> buffer =
-			store.InstallIndexerSetter<int, string, bool>(0);
+			store.GetOrCreateBuffer<FastIndexerSetterBuffer<int, string, bool>>(0,
+				static f => new FastIndexerSetterBuffer<int, string, bool>(f));
 		buffer.Append(1, "a", true);
 		buffer.Append(1, "a", false);
 		buffer.Append(2, "a", true);
@@ -129,7 +136,8 @@ public async Task IndexerSetter3CountSource_ShouldHonorAllMatchers()
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerSetterBuffer<int, string, bool, double> buffer =
-			store.InstallIndexerSetter<int, string, bool, double>(0);
+			store.GetOrCreateBuffer<FastIndexerSetterBuffer<int, string, bool, double>>(0,
+				static f => new FastIndexerSetterBuffer<int, string, bool, double>(f));
 		buffer.Append(1, "a", true, 0.5);
 		buffer.Append(1, "a", true, 1.5);
 		buffer.Append(2, "a", true, 0.5);
@@ -148,7 +156,8 @@ public async Task IndexerSetter4CountSource_ShouldHonorAllMatchers()
 	{
 		FastMockInteractions store = new(1);
 		FastIndexerSetterBuffer<int, string, bool, double, char> buffer =
-			store.InstallIndexerSetter<int, string, bool, double, char>(0);
+			store.GetOrCreateBuffer<FastIndexerSetterBuffer<int, string, bool, double, char>>(0,
+				static f => new FastIndexerSetterBuffer<int, string, bool, double, char>(f));
 		buffer.Append(1, "a", true, 0.5, 'x');
 		buffer.Append(1, "a", true, 0.5, 'y');
 		buffer.Append(2, "a", true, 0.5, 'x');
@@ -163,11 +172,29 @@ public async Task IndexerSetter4CountSource_ShouldHonorAllMatchers()
 		await That(source.Count()).IsEqualTo(1);
 	}
 
+	[Fact]
+	public async Task Method0CountSource_CountAll_ShouldMarkSlotsVerified()
+	{
+		FastMockInteractions store = new(1);
+		FastMethod0Buffer buffer = store.GetOrCreateBuffer<FastMethod0Buffer>(0,
+			static f => new FastMethod0Buffer(f));
+		buffer.Append("M");
+		buffer.Append("M");
+
+		Method0CountSource source = new(buffer);
+		await That(source.CountAll()).IsEqualTo(2);
+
+		List<(long Seq, IInteraction Interaction)> dest = [];
+		((IFastMemberBuffer)buffer).AppendBoxedUnverified(dest);
+		await That(dest).IsEmpty();
+	}
+
 	[Fact]
 	public async Task Method0CountSource_ShouldRouteCountAndCountAllThroughBuffer()
 	{
 		FastMockInteractions store = new(1);
-		FastMethod0Buffer buffer = store.InstallMethod(0);
+		FastMethod0Buffer buffer = store.GetOrCreateBuffer<FastMethod0Buffer>(0,
+			static f => new FastMethod0Buffer(f));
 		buffer.Append("M");
 		buffer.Append("M");
 
@@ -177,11 +204,29 @@ public async Task Method0CountSource_ShouldRouteCountAndCountAllThroughBuffer()
 		await That(source.Count()).IsEqualTo(2);
 	}
 
+	[Fact]
+	public async Task Method1CountSource_CountAll_ShouldMarkSlotsVerified()
+	{
+		FastMockInteractions store = new(1);
+		FastMethod1Buffer<int> buffer = store.GetOrCreateBuffer<FastMethod1Buffer<int>>(0,
+			static f => new FastMethod1Buffer<int>(f));
+		buffer.Append("M", 1);
+		buffer.Append("M", 2);
+
+		Method1CountSource<int> source = new(buffer, (IParameterMatch<int>)It.Is(1));
+		await That(source.CountAll()).IsEqualTo(2);
+
+		List<(long Seq, IInteraction Interaction)> dest = [];
+		((IFastMemberBuffer)buffer).AppendBoxedUnverified(dest);
+		await That(dest).IsEmpty();
+	}
+
 	[Fact]
 	public async Task Method1CountSource_ShouldHonorMatcher()
 	{
 		FastMockInteractions store = new(1);
-		FastMethod1Buffer<int> buffer = store.InstallMethod<int>(0);
+		FastMethod1Buffer<int> buffer = store.GetOrCreateBuffer<FastMethod1Buffer<int>>(0,
+			static f => new FastMethod1Buffer<int>(f));
 		buffer.Append("M", 1);
 		buffer.Append("M", 2);
 		buffer.Append("M", 1);
@@ -197,85 +242,55 @@ public async Task Method1CountSource_ShouldHonorMatcher()
 	}
 
 	[Fact]
-	public async Task Method2CountSource_ShouldHonorBothMatchers()
+	public async Task Method2CountSource_CountAll_ShouldMarkSlotsVerified()
 	{
 		FastMockInteractions store = new(1);
-		FastMethod2Buffer<int, string> buffer = store.InstallMethod<int, string>(0);
+		FastMethod2Buffer<int, string> buffer = store.GetOrCreateBuffer<FastMethod2Buffer<int, string>>(0,
+			static f => new FastMethod2Buffer<int, string>(f));
 		buffer.Append("M", 1, "a");
-		buffer.Append("M", 2, "a");
-		buffer.Append("M", 1, "b");
+		buffer.Append("M", 2, "b");
 
 		Method2CountSource<int, string> source = new(buffer,
 			(IParameterMatch<int>)It.Is(1),
 			(IParameterMatch<string>)It.Is<string>("a"));
+		await That(source.CountAll()).IsEqualTo(2);
 
-		await That(source.CountAll()).IsEqualTo(3);
-		await That(source.Count()).IsEqualTo(1);
+		List<(long Seq, IInteraction Interaction)> dest = [];
+		((IFastMemberBuffer)buffer).AppendBoxedUnverified(dest);
+		await That(dest).IsEmpty();
 	}
 
 	[Fact]
-	public async Task Method3CountSource_ShouldHonorAllThreeMatchers()
+	public async Task Method2CountSource_ShouldHonorBothMatchers()
 	{
 		FastMockInteractions store = new(1);
-		FastMethod3Buffer<int, string, bool> buffer = store.InstallMethod<int, string, bool>(0);
-		buffer.Append("M", 1, "a", true);
-		buffer.Append("M", 2, "a", false);
-		buffer.Append("M", 1, "b", true);
+		FastMethod2Buffer<int, string> buffer = store.GetOrCreateBuffer<FastMethod2Buffer<int, string>>(0,
+			static f => new FastMethod2Buffer<int, string>(f));
+		buffer.Append("M", 1, "a");
+		buffer.Append("M", 2, "a");
+		buffer.Append("M", 1, "b");
 
-		Method3CountSource<int, string, bool> source = new(buffer,
+		Method2CountSource<int, string> source = new(buffer,
 			(IParameterMatch<int>)It.Is(1),
-			(IParameterMatch<string>)It.IsAny<string>(),
-			(IParameterMatch<bool>)It.Is(true));
+			(IParameterMatch<string>)It.Is<string>("a"));
 
 		await That(source.CountAll()).IsEqualTo(3);
-		await That(source.Count()).IsEqualTo(2);
+		await That(source.Count()).IsEqualTo(1);
 	}
 
 	[Fact]
-	public async Task Method4CountSource_ShouldHonorAllFourMatchers()
+	public async Task Method3CountSource_CountAll_ShouldMarkSlotsVerified()
 	{
 		FastMockInteractions store = new(1);
-		FastMethod4Buffer<int, string, bool, double> buffer =
-			store.InstallMethod<int, string, bool, double>(0);
-		buffer.Append("M", 1, "a", true, 0.5);
-		buffer.Append("M", 2, "a", false, 1.5);
-		buffer.Append("M", 1, "a", true, 2.5);
+		FastMethod3Buffer<int, string, bool> buffer = store.GetOrCreateBuffer<FastMethod3Buffer<int, string, bool>>(0,
+			static f => new FastMethod3Buffer<int, string, bool>(f));
+		buffer.Append("M", 1, "a", true);
+		buffer.Append("M", 2, "b", false);
 
-		Method4CountSource<int, string, bool, double> source = new(buffer,
+		Method3CountSource<int, string, bool> source = new(buffer,
 			(IParameterMatch<int>)It.Is(1),
 			(IParameterMatch<string>)It.Is<string>("a"),
-			(IParameterMatch<bool>)It.Is(true),
-			(IParameterMatch<double>)It.IsAny<double>());
-
-		await That(source.CountAll()).IsEqualTo(3);
-		await That(source.Count()).IsEqualTo(2);
-	}
-
-	[Fact]
-	public async Task Method0CountSource_CountAll_ShouldMarkSlotsVerified()
-	{
-		FastMockInteractions store = new(1);
-		FastMethod0Buffer buffer = store.InstallMethod(0);
-		buffer.Append("M");
-		buffer.Append("M");
-
-		Method0CountSource source = new(buffer);
-		await That(source.CountAll()).IsEqualTo(2);
-
-		List<(long Seq, IInteraction Interaction)> dest = [];
-		((IFastMemberBuffer)buffer).AppendBoxedUnverified(dest);
-		await That(dest).IsEmpty();
-	}
-
-	[Fact]
-	public async Task Method1CountSource_CountAll_ShouldMarkSlotsVerified()
-	{
-		FastMockInteractions store = new(1);
-		FastMethod1Buffer<int> buffer = store.InstallMethod<int>(0);
-		buffer.Append("M", 1);
-		buffer.Append("M", 2);
-
-		Method1CountSource<int> source = new(buffer, (IParameterMatch<int>)It.Is(1));
+			(IParameterMatch<bool>)It.Is(true));
 		await That(source.CountAll()).IsEqualTo(2);
 
 		List<(long Seq, IInteraction Interaction)> dest = [];
@@ -284,35 +299,39 @@ public async Task Method1CountSource_CountAll_ShouldMarkSlotsVerified()
 	}
 
 	[Fact]
-	public async Task Method2CountSource_CountAll_ShouldMarkSlotsVerified()
+	public async Task Method3CountSource_ShouldHonorAllThreeMatchers()
 	{
 		FastMockInteractions store = new(1);
-		FastMethod2Buffer<int, string> buffer = store.InstallMethod<int, string>(0);
-		buffer.Append("M", 1, "a");
-		buffer.Append("M", 2, "b");
+		FastMethod3Buffer<int, string, bool> buffer = store.GetOrCreateBuffer<FastMethod3Buffer<int, string, bool>>(0,
+			static f => new FastMethod3Buffer<int, string, bool>(f));
+		buffer.Append("M", 1, "a", true);
+		buffer.Append("M", 2, "a", false);
+		buffer.Append("M", 1, "b", true);
 
-		Method2CountSource<int, string> source = new(buffer,
+		Method3CountSource<int, string, bool> source = new(buffer,
 			(IParameterMatch<int>)It.Is(1),
-			(IParameterMatch<string>)It.Is<string>("a"));
-		await That(source.CountAll()).IsEqualTo(2);
+			(IParameterMatch<string>)It.IsAny<string>(),
+			(IParameterMatch<bool>)It.Is(true));
 
-		List<(long Seq, IInteraction Interaction)> dest = [];
-		((IFastMemberBuffer)buffer).AppendBoxedUnverified(dest);
-		await That(dest).IsEmpty();
+		await That(source.CountAll()).IsEqualTo(3);
+		await That(source.Count()).IsEqualTo(2);
 	}
 
 	[Fact]
-	public async Task Method3CountSource_CountAll_ShouldMarkSlotsVerified()
+	public async Task Method4CountSource_CountAll_ShouldMarkSlotsVerified()
 	{
 		FastMockInteractions store = new(1);
-		FastMethod3Buffer<int, string, bool> buffer = store.InstallMethod<int, string, bool>(0);
-		buffer.Append("M", 1, "a", true);
-		buffer.Append("M", 2, "b", false);
+		FastMethod4Buffer<int, string, bool, double> buffer =
+			store.GetOrCreateBuffer<FastMethod4Buffer<int, string, bool, double>>(0,
+				static f => new FastMethod4Buffer<int, string, bool, double>(f));
+		buffer.Append("M", 1, "a", true, 0.5);
+		buffer.Append("M", 2, "b", false, 1.5);
 
-		Method3CountSource<int, string, bool> source = new(buffer,
+		Method4CountSource<int, string, bool, double> source = new(buffer,
 			(IParameterMatch<int>)It.Is(1),
 			(IParameterMatch<string>)It.Is<string>("a"),
-			(IParameterMatch<bool>)It.Is(true));
+			(IParameterMatch<bool>)It.Is(true),
+			(IParameterMatch<double>)It.Is(0.5));
 		await That(source.CountAll()).IsEqualTo(2);
 
 		List<(long Seq, IInteraction Interaction)> dest = [];
@@ -321,34 +340,35 @@ public async Task Method3CountSource_CountAll_ShouldMarkSlotsVerified()
 	}
 
 	[Fact]
-	public async Task Method4CountSource_CountAll_ShouldMarkSlotsVerified()
+	public async Task Method4CountSource_ShouldHonorAllFourMatchers()
 	{
 		FastMockInteractions store = new(1);
 		FastMethod4Buffer<int, string, bool, double> buffer =
-			store.InstallMethod<int, string, bool, double>(0);
+			store.GetOrCreateBuffer<FastMethod4Buffer<int, string, bool, double>>(0,
+				static f => new FastMethod4Buffer<int, string, bool, double>(f));
 		buffer.Append("M", 1, "a", true, 0.5);
-		buffer.Append("M", 2, "b", false, 1.5);
+		buffer.Append("M", 2, "a", false, 1.5);
+		buffer.Append("M", 1, "a", true, 2.5);
 
 		Method4CountSource<int, string, bool, double> source = new(buffer,
 			(IParameterMatch<int>)It.Is(1),
 			(IParameterMatch<string>)It.Is<string>("a"),
 			(IParameterMatch<bool>)It.Is(true),
-			(IParameterMatch<double>)It.Is(0.5));
-		await That(source.CountAll()).IsEqualTo(2);
+			(IParameterMatch<double>)It.IsAny<double>());
 
-		List<(long Seq, IInteraction Interaction)> dest = [];
-		((IFastMemberBuffer)buffer).AppendBoxedUnverified(dest);
-		await That(dest).IsEmpty();
+		await That(source.CountAll()).IsEqualTo(3);
+		await That(source.Count()).IsEqualTo(2);
 	}
 
 	[Fact]
 	public async Task PropertyGetterCountSource_ShouldReturnRecordedCount()
 	{
 		FastMockInteractions store = new(1);
-		FastPropertyGetterBuffer buffer = store.InstallPropertyGetter(0);
-		buffer.Append("P");
-		buffer.Append("P");
-		buffer.Append("P");
+		FastPropertyGetterBuffer buffer = store.GetOrCreateBuffer<FastPropertyGetterBuffer>(0,
+			static f => new FastPropertyGetterBuffer(f, new PropertyGetterAccess("P")));
+		buffer.Append();
+		buffer.Append();
+		buffer.Append();
 
 		PropertyGetterCountSource source = new(buffer);
 
@@ -359,7 +379,8 @@ public async Task PropertyGetterCountSource_ShouldReturnRecordedCount()
 	public async Task PropertySetterCountSource_ShouldHonorValueMatcher()
 	{
 		FastMockInteractions store = new(1);
-		FastPropertySetterBuffer<int> buffer = store.InstallPropertySetter<int>(0);
+		FastPropertySetterBuffer<int> buffer = store.GetOrCreateBuffer<FastPropertySetterBuffer<int>>(0,
+			static f => new FastPropertySetterBuffer<int>(f));
 		buffer.Append("P", 1);
 		buffer.Append("P", 2);
 		buffer.Append("P", 1);
diff --git a/Tests/Mockolate.Internal.Tests/Verify/TypedVerifyFastPathTests.cs b/Tests/Mockolate.Internal.Tests/Verify/TypedVerifyFastPathTests.cs
index fff032f6..b3db8ce0 100644
--- a/Tests/Mockolate.Internal.Tests/Verify/TypedVerifyFastPathTests.cs
+++ b/Tests/Mockolate.Internal.Tests/Verify/TypedVerifyFastPathTests.cs
@@ -12,7 +12,8 @@ public class TypedVerifyFastPathTests
 	public async Task IndexerGot_WithMemberIdAndBuffer_CountsBufferEntriesAndProducesExpectation()
 	{
 		FastMockInteractions store = new(1);
-		FastIndexerGetterBuffer<int> buffer = store.InstallIndexerGetter<int>(0);
+		FastIndexerGetterBuffer<int> buffer = store.GetOrCreateBuffer<FastIndexerGetterBuffer<int>>(0,
+			static f => new FastIndexerGetterBuffer<int>(f));
 		MockRegistry registry = new(MockBehavior.Default, store);
 		buffer.Append(5);
 		buffer.Append(7);
@@ -31,7 +32,7 @@ public async Task IndexerGot_WithMemberIdAndBuffer_CountsBufferEntriesAndProduce
 	public async Task IndexerGot_WithMemberIdAndInstalledBuffer_OnlyWalksBuffer()
 	{
 		FastMockInteractions store = new(1);
-		store.InstallPropertyGetter(0);
+		InstallPropertyGetter(store, 0);
 		MockRegistry registry = new(MockBehavior.Default, store);
 		IMockInteractions interactions = store;
 
@@ -64,7 +65,8 @@ public async Task IndexerGot_WithoutBuffer_ProducesParametersDescriptionInExpect
 	public async Task IndexerGotTyped_WithBuffer_ProducesParametersDescriptionInExpectation()
 	{
 		FastMockInteractions store = new(1);
-		store.InstallIndexerGetter<int>(0);
+		store.GetOrCreateBuffer<FastIndexerGetterBuffer<int>>(0,
+			static f => new FastIndexerGetterBuffer<int>(f));
 		MockRegistry registry = new(MockBehavior.Default, store);
 
 		VerificationResult<object> result = registry.IndexerGotTyped(
@@ -79,7 +81,8 @@ public async Task IndexerGotTyped_WithBuffer_ProducesParametersDescriptionInExpe
 	public async Task IndexerSet_WithMemberIdAndBuffer_CountsMatchingValuesAndProducesExpectation()
 	{
 		FastMockInteractions store = new(1);
-		FastIndexerSetterBuffer<int, string> buffer = store.InstallIndexerSetter<int, string>(0);
+		FastIndexerSetterBuffer<int, string> buffer = store.GetOrCreateBuffer<FastIndexerSetterBuffer<int, string>>(0,
+			static f => new FastIndexerSetterBuffer<int, string>(f));
 		MockRegistry registry = new(MockBehavior.Default, store);
 		buffer.Append(5, "v");
 		buffer.Append(7, "v");
@@ -101,7 +104,7 @@ public async Task IndexerSet_WithMemberIdAndBuffer_CountsMatchingValuesAndProduc
 	public async Task IndexerSet_WithMemberIdAndInstalledBuffer_OnlyWalksBuffer()
 	{
 		FastMockInteractions store = new(1);
-		store.InstallPropertyGetter(0);
+		InstallPropertyGetter(store, 0);
 		MockRegistry registry = new(MockBehavior.Default, store);
 		IMockInteractions interactions = store;
 
@@ -139,7 +142,8 @@ public async Task IndexerSet_WithoutBuffer_ProducesParametersDescriptionInExpect
 	public async Task IndexerSetTyped_WithBuffer_ProducesParametersDescriptionInExpectation()
 	{
 		FastMockInteractions store = new(1);
-		store.InstallIndexerSetter<int, string>(0);
+		store.GetOrCreateBuffer<FastIndexerSetterBuffer<int, string>>(0,
+			static f => new FastIndexerSetterBuffer<int, string>(f));
 		MockRegistry registry = new(MockBehavior.Default, store);
 
 		IParameterMatch<string> value = (IParameterMatch<string>)It.Is("v");
@@ -157,7 +161,8 @@ public async Task IndexerSetTyped_WithBuffer_ProducesParametersDescriptionInExpe
 	public async Task SubscribedTo_WithMemberIdAndBuffer_CountsBufferEntriesAndProducesExpectation()
 	{
 		FastMockInteractions store = new(1);
-		FastEventBuffer buffer = store.InstallEventSubscribe(0);
+		FastEventBuffer buffer = store.GetOrCreateBuffer<FastEventBuffer>(0,
+			static f => new FastEventBuffer(f, FastEventBufferKind.Subscribe));
 		MockRegistry registry = new(MockBehavior.Default, store);
 		MethodInfo method = typeof(TypedVerifyFastPathTests).GetMethod(
 			nameof(SubscribedTo_WithMemberIdAndBuffer_CountsBufferEntriesAndProducesExpectation))!;
@@ -192,7 +197,8 @@ public async Task SubscribedTo_WithMemberIdButNoBuffer_FallsBackAndFiltersByName
 	public async Task SubscribedToTyped_WithBuffer_ProducesEventNameInExpectation()
 	{
 		FastMockInteractions store = new(1);
-		store.InstallEventSubscribe(0);
+		store.GetOrCreateBuffer<FastEventBuffer>(0,
+			static f => new FastEventBuffer(f, FastEventBufferKind.Subscribe));
 		MockRegistry registry = new(MockBehavior.Default, store);
 
 		VerificationResult<object> result = registry.SubscribedToTyped(new object(), 0, "OnFoo");
@@ -215,7 +221,8 @@ public async Task SubscribedToTyped_WithMemberIdButNoBuffer_FallsBackToStringKey
 	public async Task TryGetBuffer_WhenBufferReturned_TypedFastPathIgnoresOtherInteractions()
 	{
 		FastMockInteractions store = new(1);
-		FastMethod0Buffer buffer = store.InstallMethod(0);
+		FastMethod0Buffer buffer = store.GetOrCreateBuffer<FastMethod0Buffer>(0,
+			static f => new FastMethod0Buffer(f));
 		MockRegistry registry = new(MockBehavior.Default, store);
 		IMockInteractions interactions = store;
 
@@ -233,7 +240,8 @@ public async Task TryGetBuffer_WhenBufferReturned_TypedFastPathIgnoresOtherInter
 	public async Task UnsubscribedFrom_WithMemberIdAndBuffer_CountsBufferEntriesAndProducesExpectation()
 	{
 		FastMockInteractions store = new(1);
-		FastEventBuffer buffer = store.InstallEventUnsubscribe(0);
+		FastEventBuffer buffer = store.GetOrCreateBuffer<FastEventBuffer>(0,
+			static f => new FastEventBuffer(f, FastEventBufferKind.Unsubscribe));
 		MockRegistry registry = new(MockBehavior.Default, store);
 		MethodInfo method = typeof(TypedVerifyFastPathTests).GetMethod(
 			nameof(UnsubscribedFrom_WithMemberIdAndBuffer_CountsBufferEntriesAndProducesExpectation))!;
@@ -268,7 +276,8 @@ public async Task UnsubscribedFrom_WithMemberIdButNoBuffer_FallsBackAndFiltersBy
 	public async Task UnsubscribedFromTyped_WithBuffer_ProducesEventNameInExpectation()
 	{
 		FastMockInteractions store = new(1);
-		store.InstallEventUnsubscribe(0);
+		store.GetOrCreateBuffer<FastEventBuffer>(0,
+			static f => new FastEventBuffer(f, FastEventBufferKind.Unsubscribe));
 		MockRegistry registry = new(MockBehavior.Default, store);
 
 		VerificationResult<object> result = registry.UnsubscribedFromTyped(new object(), 0, "OnFoo");
@@ -291,7 +300,7 @@ public async Task UnsubscribedFromTyped_WithMemberIdButNoBuffer_FallsBackToStrin
 	public async Task UnsubscribedFromTyped_WithMemberIdButNonMatchingBufferKind_FallsBackToStringKeyedPath()
 	{
 		FastMockInteractions store = new(1);
-		store.InstallMethod(0);
+		store.GetOrCreateBuffer<FastMethod0Buffer>(0, static f => new FastMethod0Buffer(f));
 		MockRegistry registry = new(MockBehavior.Default, store);
 
 		VerificationResult<object> result = registry.UnsubscribedFromTyped(new object(), 0, "OnFoo");
@@ -304,7 +313,8 @@ public async Task UnsubscribedFromTyped_WithMemberIdButNonMatchingBufferKind_Fal
 	public async Task VerifyMethod0_TypedFastPath_ShouldCount()
 	{
 		FastMockInteractions store = new(1);
-		FastMethod0Buffer buffer = store.InstallMethod(0);
+		FastMethod0Buffer buffer = store.GetOrCreateBuffer<FastMethod0Buffer>(0,
+			static f => new FastMethod0Buffer(f));
 
 		MockRegistry registry = new(MockBehavior.Default, store);
 
@@ -337,7 +347,8 @@ public async Task VerifyMethod0_WithMemberIdButNoMatchingBuffer_FallbackPredicat
 	public async Task VerifyMethod1_TypedFastPath_FailsWithExpectedMessage()
 	{
 		FastMockInteractions store = new(1);
-		FastMethod1Buffer<int> buffer = store.InstallMethod<int>(0);
+		FastMethod1Buffer<int> buffer = store.GetOrCreateBuffer<FastMethod1Buffer<int>>(0,
+			static f => new FastMethod1Buffer<int>(f));
 
 		MockRegistry registry = new(MockBehavior.Default, store);
 
@@ -353,7 +364,8 @@ await That(() => registry.VerifyMethod(new object(), 0, "Foo",
 	public async Task VerifyMethod1_TypedFastPath_ShouldHonorMatcher()
 	{
 		FastMockInteractions store = new(1);
-		FastMethod1Buffer<int> buffer = store.InstallMethod<int>(0);
+		FastMethod1Buffer<int> buffer = store.GetOrCreateBuffer<FastMethod1Buffer<int>>(0,
+			static f => new FastMethod1Buffer<int>(f));
 
 		MockRegistry registry = new(MockBehavior.Default, store);
 
@@ -373,7 +385,8 @@ public async Task VerifyMethod1_TypedFastPath_ShouldHonorMatcher()
 	public async Task VerifyMethod2_TypedFastPath_AnyParameters_UsesCountAll()
 	{
 		FastMockInteractions store = new(1);
-		FastMethod2Buffer<int, string> buffer = store.InstallMethod<int, string>(0);
+		FastMethod2Buffer<int, string> buffer = store.GetOrCreateBuffer<FastMethod2Buffer<int, string>>(0,
+			static f => new FastMethod2Buffer<int, string>(f));
 
 		MockRegistry registry = new(MockBehavior.Default, store);
 
@@ -444,10 +457,10 @@ public async Task VerifyMethod4_FallbackPath_RequiresAllParametersToMatch()
 	public async Task VerifyProperty_GetterWithMemberIdAndBuffer_CountsBufferEntriesAndProducesExpectation()
 	{
 		FastMockInteractions store = new(1);
-		FastPropertyGetterBuffer buffer = store.InstallPropertyGetter(0);
+		FastPropertyGetterBuffer buffer = InstallPropertyGetter(store, 0);
 		MockRegistry registry = new(MockBehavior.Default, store);
-		buffer.Append("P");
-		buffer.Append("P");
+		buffer.Append();
+		buffer.Append();
 
 		VerificationResult<object> result = registry.VerifyProperty(new object(), 0, "P");
 
@@ -459,7 +472,8 @@ public async Task VerifyProperty_GetterWithMemberIdAndBuffer_CountsBufferEntries
 	public async Task VerifyProperty_SetterWithMemberIdAndBuffer_CountsMatchingValuesAndProducesExpectation()
 	{
 		FastMockInteractions store = new(1);
-		FastPropertySetterBuffer<int> buffer = store.InstallPropertySetter<int>(0);
+		FastPropertySetterBuffer<int> buffer = store.GetOrCreateBuffer<FastPropertySetterBuffer<int>>(0,
+			static f => new FastPropertySetterBuffer<int>(f));
 		MockRegistry registry = new(MockBehavior.Default, store);
 		buffer.Append("P", 1);
 		buffer.Append("P", 2);
@@ -543,7 +557,7 @@ public async Task VerifyPropertySetter_WithMemberIdButNoBuffer_FallsBackToString
 	public async Task VerifyPropertyTyped_Getter_WithBuffer_ProducesPropertyNameInExpectation()
 	{
 		FastMockInteractions store = new(1);
-		store.InstallPropertyGetter(0);
+		InstallPropertyGetter(store, 0);
 		MockRegistry registry = new(MockBehavior.Default, store);
 
 		VerificationResult<object> result = registry.VerifyPropertyTyped(new object(), 0, "P");
@@ -555,7 +569,8 @@ public async Task VerifyPropertyTyped_Getter_WithBuffer_ProducesPropertyNameInEx
 	public async Task VerifyPropertyTyped_Setter_WithBuffer_ProducesPropertyNameInExpectation()
 	{
 		FastMockInteractions store = new(1);
-		store.InstallPropertySetter<int>(0);
+		store.GetOrCreateBuffer<FastPropertySetterBuffer<int>>(0,
+			static f => new FastPropertySetterBuffer<int>(f));
 		MockRegistry registry = new(MockBehavior.Default, store);
 
 		IParameterMatch<int> value = (IParameterMatch<int>)It.Is(42);
@@ -564,4 +579,8 @@ public async Task VerifyPropertyTyped_Setter_WithBuffer_ProducesPropertyNameInEx
 		await That(((IVerificationResult)result).Expectation).Contains("set property P");
 		await That(((IVerificationResult)result).Expectation).Contains(value.ToString()!);
 	}
+
+	private static FastPropertyGetterBuffer InstallPropertyGetter(FastMockInteractions store, int memberId)
+		=> store.GetOrCreateBuffer<FastPropertyGetterBuffer>(memberId,
+			static f => new FastPropertyGetterBuffer(f, new PropertyGetterAccess(string.Empty)));
 }
diff --git a/Tests/Mockolate.Internal.Tests/Verify/VerificationResultTests.cs b/Tests/Mockolate.Internal.Tests/Verify/VerificationResultTests.cs
index c0f9343b..c184fa89 100644
--- a/Tests/Mockolate.Internal.Tests/Verify/VerificationResultTests.cs
+++ b/Tests/Mockolate.Internal.Tests/Verify/VerificationResultTests.cs
@@ -11,6 +11,12 @@ namespace Mockolate.Internal.Tests.Verify;
 
 public class VerificationResultTests
 {
+	private static FastMethod0Buffer InstallMethod(FastMockInteractions store, int memberId)
+		=> store.GetOrCreateBuffer<FastMethod0Buffer>(memberId, static f => new FastMethod0Buffer(f));
+
+	private static FastMethod1Buffer<T> InstallMethod<T>(FastMockInteractions store, int memberId)
+		=> store.GetOrCreateBuffer<FastMethod1Buffer<T>>(memberId, static f => new FastMethod1Buffer<T>(f));
+
 	public sealed class AwaitableTests
 	{
 		[Fact]
@@ -37,12 +43,12 @@ void Act()
 		public async Task VerifyCount_WhenPredicateNeverSatisfies_ShouldTimeOut()
 		{
 			FastMockInteractions store = new(1);
-			store.InstallMethod(0);
+			InstallMethod(store, 0);
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			void Act()
 			{
-				registry.VerifyMethod<object>(new object(), 0, "Foo", () => "Foo()")
+				registry.VerifyMethod(new object(), 0, "Foo", () => "Foo()")
 					.Within(50.Milliseconds()).AtLeast(2);
 			}
 
@@ -60,7 +66,7 @@ public async Task VerifyCount_WithUseCountAll_ShouldPickCountAllNotFilteredCount
 			// (Count()) of the mutated conditional satisfies it synchronously, then short-circuits
 			// before the async loop can re-evaluate via the unmutated CountAll().
 			FastMockInteractions store = new(1);
-			FastMethod1Buffer<int> buffer = store.InstallMethod<int>(0);
+			FastMethod1Buffer<int> buffer = InstallMethod<int>(store, 0);
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			buffer.Append("Foo", 1);
@@ -86,7 +92,7 @@ void Act()
 		public async Task WithCancellation_PreservesUseCountAllFlag()
 		{
 			FastMockInteractions store = new(1);
-			FastMethod1Buffer<int> buffer = store.InstallMethod<int>(0);
+			FastMethod1Buffer<int> buffer = InstallMethod<int>(store, 0);
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			buffer.Append("Foo", 1);
@@ -112,7 +118,7 @@ void Act()
 		public async Task Within_PreservesUseCountAllFlag()
 		{
 			FastMockInteractions store = new(1);
-			FastMethod1Buffer<int> buffer = store.InstallMethod<int>(0);
+			FastMethod1Buffer<int> buffer = InstallMethod<int>(store, 0);
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			buffer.Append("Foo", 1);
@@ -167,8 +173,8 @@ public async Task Map_WhenBufferOnlyAndFastSourceNull_PreservesBuffer()
 			// CollectMatching falls back to a global Where over _interactions, which would pick up
 			// records from OTHER buffers that satisfy the (un-name-filtered) predicate.
 			FastMockInteractions store = new(2);
-			FastMethod1Buffer<int> bufA = store.InstallMethod<int>(0);
-			FastMethod1Buffer<int> bufB = store.InstallMethod<int>(1);
+			FastMethod1Buffer<int> bufA = InstallMethod<int>(store, 0);
+			FastMethod1Buffer<int> bufB = InstallMethod<int>(store, 1);
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			bufA.Append("Foo", 1);
@@ -196,14 +202,14 @@ public async Task Map_WhenBufferOnlyAndFastSourceNull_PreservesBuffer()
 		public async Task Map_WithBuffer_PreservesFastPathSource()
 		{
 			FastMockInteractions store = new(1);
-			FastMethod0Buffer buffer = store.InstallMethod(0);
+			FastMethod0Buffer buffer = InstallMethod(store, 0);
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			buffer.Append("Foo");
 			buffer.Append("Foo");
 
 			object original = new();
-			VerificationResult<object>.IgnoreParameters result = registry.VerifyMethod<object>(
+			VerificationResult<object>.IgnoreParameters result = registry.VerifyMethod(
 				original, 0, "Foo", () => "Foo()");
 
 			string newSubject = "newMock";
@@ -245,7 +251,7 @@ public async Task WithBufferAndExactlyTwoRecords_PreservesSequenceOrder()
 			// with the existing N=1 / N=3 / N=0 cases, this pins the boundary so flipping `> 1` to
 			// `>= 1` is no longer a silent rewrite of the sort path.
 			FastMockInteractions store = new(1);
-			FastMethod1Buffer<int> buffer = store.InstallMethod<int>(0);
+			FastMethod1Buffer<int> buffer = InstallMethod<int>(store, 0);
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			buffer.Append("Foo", 10);
@@ -274,7 +280,7 @@ public async Task WithBufferAndExactlyTwoRecords_PreservesSequenceOrder()
 		public async Task WithBufferAndMultipleRecords_PreservesSequenceOrder()
 		{
 			FastMockInteractions store = new(1);
-			FastMethod1Buffer<int> buffer = store.InstallMethod<int>(0);
+			FastMethod1Buffer<int> buffer = InstallMethod<int>(store, 0);
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			buffer.Append("Foo", 10);
@@ -303,7 +309,7 @@ public async Task WithBufferAndMultipleRecords_PreservesSequenceOrder()
 		public async Task WithBufferAndNoMatchingRecord_ReturnsEmpty()
 		{
 			FastMockInteractions store = new(1);
-			FastMethod1Buffer<int> buffer = store.InstallMethod<int>(0);
+			FastMethod1Buffer<int> buffer = InstallMethod<int>(store, 0);
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			buffer.Append("Foo", 1);
@@ -326,7 +332,7 @@ public async Task WithBufferAndNoMatchingRecord_ReturnsEmpty()
 		public async Task WithBufferAndSingleRecord_ReturnsRecord()
 		{
 			FastMockInteractions store = new(1);
-			FastMethod0Buffer buffer = store.InstallMethod(0);
+			FastMethod0Buffer buffer = InstallMethod(store, 0);
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			buffer.Append("Foo");
@@ -349,7 +355,7 @@ public async Task WithBufferAndSingleRecord_ReturnsRecord()
 		public async Task WithEmptyBuffer_ReturnsEmpty()
 		{
 			FastMockInteractions store = new(1);
-			store.InstallMethod(0);
+			InstallMethod(store, 0);
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			VerificationResult<object>.IgnoreParameters result = registry.VerifyMethod<object, IMethodInteraction>(
@@ -394,7 +400,7 @@ public async Task VerifyCount_WhenRecordingDisabled_AndAwaitableViaWithin_Should
 		{
 			// Same guard, Awaitable path (via Within). Distinct mutation site.
 			FastMockInteractions store = new(1, true);
-			store.InstallMethod(0);
+			InstallMethod(store, 0);
 			MockRegistry registry = new(MockBehavior.Default with
 			{
 				SkipInteractionRecording = true,
@@ -402,7 +408,7 @@ public async Task VerifyCount_WhenRecordingDisabled_AndAwaitableViaWithin_Should
 
 			void Act()
 			{
-				registry.VerifyMethod<object>(new object(), 0, "Foo", () => "Foo()")
+				registry.VerifyMethod(new object(), 0, "Foo", () => "Foo()")
 					.Within(50.Milliseconds()).Once();
 			}
 
@@ -417,7 +423,7 @@ public async Task VerifyCount_WhenRecordingDisabled_ShouldThrowMockException()
 			// IFastVerifyCountResult.VerifyCount path. Without the guard, Once() would silently
 			// report a (probably false) count and never throw.
 			FastMockInteractions store = new(1, true);
-			store.InstallMethod(0);
+			InstallMethod(store, 0);
 			MockRegistry registry = new(MockBehavior.Default with
 			{
 				SkipInteractionRecording = true,
@@ -425,7 +431,7 @@ public async Task VerifyCount_WhenRecordingDisabled_ShouldThrowMockException()
 
 			void Act()
 			{
-				registry.VerifyMethod<object>(new object(), 0, "Foo", () => "Foo()").Once();
+				registry.VerifyMethod(new object(), 0, "Foo", () => "Foo()").Once();
 			}
 
 			await That(Act).Throws<MockException>()
diff --git a/Tests/Mockolate.SourceGenerators.Tests/MockTests.ClassTests.MethodTests.cs b/Tests/Mockolate.SourceGenerators.Tests/MockTests.ClassTests.MethodTests.cs
index aa563af2..91ff560b 100644
--- a/Tests/Mockolate.SourceGenerators.Tests/MockTests.ClassTests.MethodTests.cs
+++ b/Tests/Mockolate.SourceGenerators.Tests/MockTests.ClassTests.MethodTests.cs
@@ -1424,9 +1424,9 @@ public interface IStaticOps
 				await That(result.Sources).ContainsKey("Mock.IStaticOps.g.cs");
 				await That(result.Sources["Mock.IStaticOps.g.cs"])
 					.Contains("global::Mockolate.Interactions.FastMethod1Buffer<int>").And
-					.Contains("MockRegistryProvider.Value.Interactions).Buffers[")
+					.Contains("MockRegistryProvider.Value.Interactions).GetOrCreateBuffer<")
 					.Because(
-						"static methods record interactions via the typed FastMethodBuffer accessed through the AsyncLocal-backed registry")
+						"static methods record interactions via the typed FastMethodBuffer accessed through the AsyncLocal-backed registry; the buffer is now lazily materialized on first touch via GetOrCreateBuffer")
 					.And
 					.Contains("Append(\"global::MyCode.IStaticOps.DoIt\", value)")
 					.Because("the static-method fast-buffer branch must include the call argument when arity > 0");
diff --git a/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/BaseClass_WithMultipleAdditionalInterfaces_CanBeCreated/Mock.ComprehensiveAbstractClass.g.cs b/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/BaseClass_WithMultipleAdditionalInterfaces_CanBeCreated/Mock.ComprehensiveAbstractClass.g.cs
index d6f26d81..6665ca37 100644
--- a/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/BaseClass_WithMultipleAdditionalInterfaces_CanBeCreated/Mock.ComprehensiveAbstractClass.g.cs
+++ b/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/BaseClass_WithMultipleAdditionalInterfaces_CanBeCreated/Mock.ComprehensiveAbstractClass.g.cs
@@ -511,16 +511,10 @@ internal class ComprehensiveAbstractClass :
 
 		/// <summary>
 		///     Creates a <see cref="global::Mockolate.Interactions.FastMockInteractions">FastMockInteractions</see> sized to <see cref="MemberCount">MemberCount</see> for use as the mock's interaction store.
+		///     Per-member buffers are not allocated up-front: the recording hot paths call <see cref="global::Mockolate.Interactions.FastMockInteractions.GetOrCreateBuffer{TBuffer}(int, global::System.Func{global::Mockolate.Interactions.FastMockInteractions, TBuffer})">GetOrCreateBuffer&lt;TBuffer&gt;(int, Func&lt;FastMockInteractions, TBuffer&gt;)</see> so a slot is materialized only when its member is first invoked.
 		/// </summary>
 		internal static global::Mockolate.Interactions.FastMockInteractions CreateFastInteractions(global::Mockolate.MockBehavior behavior)
-		{
-			global::Mockolate.Interactions.FastMockInteractions fast = new global::Mockolate.Interactions.FastMockInteractions(MemberCount, behavior.SkipInteractionRecording);
-			global::Mockolate.Interactions.FastMethodBufferFactory.InstallMethod(fast, global::Mockolate.Mock.ComprehensiveAbstractClass.MemberId_A);
-			global::Mockolate.Interactions.FastMethodBufferFactory.InstallMethod(fast, global::Mockolate.Mock.ComprehensiveAbstractClass.MemberId_P);
-			global::Mockolate.Interactions.FastPropertyBufferFactory.InstallPropertyGetter(fast, global::Mockolate.Mock.ComprehensiveAbstractClass.MemberId_V_Get, global::Mockolate.Mock.ComprehensiveAbstractClass.PropertyAccess_V_Get);
-			global::Mockolate.Interactions.FastPropertyBufferFactory.InstallPropertySetter<int>(fast, global::Mockolate.Mock.ComprehensiveAbstractClass.MemberId_V_Set);
-			return fast;
-		}
+			=> new global::Mockolate.Interactions.FastMockInteractions(MemberCount, behavior.SkipInteractionRecording);
 
 		/// <summary>
 		///     Builds a <see cref="global::Mockolate.MockRegistry">MockRegistry</see> backed by a typed-buffer-sized <see cref="global::Mockolate.Interactions.FastMockInteractions">FastMockInteractions</see> from <paramref name="behavior" />.
@@ -545,10 +539,10 @@ internal class ComprehensiveAbstractClass :
 
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastMethod0Buffer MockolateBuffer_A
-			=> field ?? (field = (global::Mockolate.Interactions.FastMethod0Buffer)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.ComprehensiveAbstractClass.MemberId_A]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod0Buffer>(global::Mockolate.Mock.ComprehensiveAbstractClass.MemberId_A, static fast => new global::Mockolate.Interactions.FastMethod0Buffer(fast)));
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastMethod0Buffer MockolateBuffer_P
-			=> field ?? (field = (global::Mockolate.Interactions.FastMethod0Buffer)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.ComprehensiveAbstractClass.MemberId_P]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod0Buffer>(global::Mockolate.Mock.ComprehensiveAbstractClass.MemberId_P, static fast => new global::Mockolate.Interactions.FastMethod0Buffer(fast)));
 
 		/// <inheritdoc />
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
diff --git a/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/BaseClass_WithMultipleAdditionalInterfaces_CanBeCreated/Mock.ICombinationMockA.g.cs b/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/BaseClass_WithMultipleAdditionalInterfaces_CanBeCreated/Mock.ICombinationMockA.g.cs
index 86d70a01..9a934d04 100644
--- a/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/BaseClass_WithMultipleAdditionalInterfaces_CanBeCreated/Mock.ICombinationMockA.g.cs
+++ b/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/BaseClass_WithMultipleAdditionalInterfaces_CanBeCreated/Mock.ICombinationMockA.g.cs
@@ -210,15 +210,10 @@ internal class ICombinationMockA :
 
 		/// <summary>
 		///     Creates a <see cref="global::Mockolate.Interactions.FastMockInteractions">FastMockInteractions</see> sized to <see cref="MemberCount">MemberCount</see> for use as the mock's interaction store.
+		///     Per-member buffers are not allocated up-front: the recording hot paths call <see cref="global::Mockolate.Interactions.FastMockInteractions.GetOrCreateBuffer{TBuffer}(int, global::System.Func{global::Mockolate.Interactions.FastMockInteractions, TBuffer})">GetOrCreateBuffer&lt;TBuffer&gt;(int, Func&lt;FastMockInteractions, TBuffer&gt;)</see> so a slot is materialized only when its member is first invoked.
 		/// </summary>
 		internal static global::Mockolate.Interactions.FastMockInteractions CreateFastInteractions(global::Mockolate.MockBehavior behavior)
-		{
-			global::Mockolate.Interactions.FastMockInteractions fast = new global::Mockolate.Interactions.FastMockInteractions(MemberCount, behavior.SkipInteractionRecording);
-			global::Mockolate.Interactions.FastMethodBufferFactory.InstallMethod(fast, global::Mockolate.Mock.ICombinationMockA.MemberId_Run);
-			global::Mockolate.Interactions.FastPropertyBufferFactory.InstallPropertyGetter(fast, global::Mockolate.Mock.ICombinationMockA.MemberId_Value_Get, global::Mockolate.Mock.ICombinationMockA.PropertyAccess_Value_Get);
-			global::Mockolate.Interactions.FastPropertyBufferFactory.InstallPropertySetter<int>(fast, global::Mockolate.Mock.ICombinationMockA.MemberId_Value_Set);
-			return fast;
-		}
+			=> new global::Mockolate.Interactions.FastMockInteractions(MemberCount, behavior.SkipInteractionRecording);
 
 		/// <summary>
 		///     Builds a <see cref="global::Mockolate.MockRegistry">MockRegistry</see> backed by a typed-buffer-sized <see cref="global::Mockolate.Interactions.FastMockInteractions">FastMockInteractions</see> from <paramref name="behavior" />.
@@ -236,7 +231,7 @@ internal class ICombinationMockA :
 
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastMethod0Buffer MockolateBuffer_Run
-			=> field ?? (field = (global::Mockolate.Interactions.FastMethod0Buffer)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.ICombinationMockA.MemberId_Run]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod0Buffer>(global::Mockolate.Mock.ICombinationMockA.MemberId_Run, static fast => new global::Mockolate.Interactions.FastMethod0Buffer(fast)));
 
 		/// <inheritdoc />
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
diff --git a/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/BaseClass_WithMultipleAdditionalInterfaces_CanBeCreated/Mock.ICombinationMockB.g.cs b/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/BaseClass_WithMultipleAdditionalInterfaces_CanBeCreated/Mock.ICombinationMockB.g.cs
index 71c02c1b..88ffb1e0 100644
--- a/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/BaseClass_WithMultipleAdditionalInterfaces_CanBeCreated/Mock.ICombinationMockB.g.cs
+++ b/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/BaseClass_WithMultipleAdditionalInterfaces_CanBeCreated/Mock.ICombinationMockB.g.cs
@@ -210,15 +210,10 @@ internal class ICombinationMockB :
 
 		/// <summary>
 		///     Creates a <see cref="global::Mockolate.Interactions.FastMockInteractions">FastMockInteractions</see> sized to <see cref="MemberCount">MemberCount</see> for use as the mock's interaction store.
+		///     Per-member buffers are not allocated up-front: the recording hot paths call <see cref="global::Mockolate.Interactions.FastMockInteractions.GetOrCreateBuffer{TBuffer}(int, global::System.Func{global::Mockolate.Interactions.FastMockInteractions, TBuffer})">GetOrCreateBuffer&lt;TBuffer&gt;(int, Func&lt;FastMockInteractions, TBuffer&gt;)</see> so a slot is materialized only when its member is first invoked.
 		/// </summary>
 		internal static global::Mockolate.Interactions.FastMockInteractions CreateFastInteractions(global::Mockolate.MockBehavior behavior)
-		{
-			global::Mockolate.Interactions.FastMockInteractions fast = new global::Mockolate.Interactions.FastMockInteractions(MemberCount, behavior.SkipInteractionRecording);
-			global::Mockolate.Interactions.FastMethodBufferFactory.InstallMethod(fast, global::Mockolate.Mock.ICombinationMockB.MemberId_Run);
-			global::Mockolate.Interactions.FastPropertyBufferFactory.InstallPropertyGetter(fast, global::Mockolate.Mock.ICombinationMockB.MemberId_Value_Get, global::Mockolate.Mock.ICombinationMockB.PropertyAccess_Value_Get);
-			global::Mockolate.Interactions.FastPropertyBufferFactory.InstallPropertySetter<int>(fast, global::Mockolate.Mock.ICombinationMockB.MemberId_Value_Set);
-			return fast;
-		}
+			=> new global::Mockolate.Interactions.FastMockInteractions(MemberCount, behavior.SkipInteractionRecording);
 
 		/// <summary>
 		///     Builds a <see cref="global::Mockolate.MockRegistry">MockRegistry</see> backed by a typed-buffer-sized <see cref="global::Mockolate.Interactions.FastMockInteractions">FastMockInteractions</see> from <paramref name="behavior" />.
@@ -236,7 +231,7 @@ internal class ICombinationMockB :
 
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastMethod0Buffer MockolateBuffer_Run
-			=> field ?? (field = (global::Mockolate.Interactions.FastMethod0Buffer)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.ICombinationMockB.MemberId_Run]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod0Buffer>(global::Mockolate.Mock.ICombinationMockB.MemberId_Run, static fast => new global::Mockolate.Interactions.FastMethod0Buffer(fast)));
 
 		/// <inheritdoc />
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
diff --git a/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/ComprehensiveAbstractClass_CanBeCreated/Mock.ComprehensiveAbstractClass.g.cs b/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/ComprehensiveAbstractClass_CanBeCreated/Mock.ComprehensiveAbstractClass.g.cs
index d6f26d81..6665ca37 100644
--- a/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/ComprehensiveAbstractClass_CanBeCreated/Mock.ComprehensiveAbstractClass.g.cs
+++ b/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/ComprehensiveAbstractClass_CanBeCreated/Mock.ComprehensiveAbstractClass.g.cs
@@ -511,16 +511,10 @@ internal class ComprehensiveAbstractClass :
 
 		/// <summary>
 		///     Creates a <see cref="global::Mockolate.Interactions.FastMockInteractions">FastMockInteractions</see> sized to <see cref="MemberCount">MemberCount</see> for use as the mock's interaction store.
+		///     Per-member buffers are not allocated up-front: the recording hot paths call <see cref="global::Mockolate.Interactions.FastMockInteractions.GetOrCreateBuffer{TBuffer}(int, global::System.Func{global::Mockolate.Interactions.FastMockInteractions, TBuffer})">GetOrCreateBuffer&lt;TBuffer&gt;(int, Func&lt;FastMockInteractions, TBuffer&gt;)</see> so a slot is materialized only when its member is first invoked.
 		/// </summary>
 		internal static global::Mockolate.Interactions.FastMockInteractions CreateFastInteractions(global::Mockolate.MockBehavior behavior)
-		{
-			global::Mockolate.Interactions.FastMockInteractions fast = new global::Mockolate.Interactions.FastMockInteractions(MemberCount, behavior.SkipInteractionRecording);
-			global::Mockolate.Interactions.FastMethodBufferFactory.InstallMethod(fast, global::Mockolate.Mock.ComprehensiveAbstractClass.MemberId_A);
-			global::Mockolate.Interactions.FastMethodBufferFactory.InstallMethod(fast, global::Mockolate.Mock.ComprehensiveAbstractClass.MemberId_P);
-			global::Mockolate.Interactions.FastPropertyBufferFactory.InstallPropertyGetter(fast, global::Mockolate.Mock.ComprehensiveAbstractClass.MemberId_V_Get, global::Mockolate.Mock.ComprehensiveAbstractClass.PropertyAccess_V_Get);
-			global::Mockolate.Interactions.FastPropertyBufferFactory.InstallPropertySetter<int>(fast, global::Mockolate.Mock.ComprehensiveAbstractClass.MemberId_V_Set);
-			return fast;
-		}
+			=> new global::Mockolate.Interactions.FastMockInteractions(MemberCount, behavior.SkipInteractionRecording);
 
 		/// <summary>
 		///     Builds a <see cref="global::Mockolate.MockRegistry">MockRegistry</see> backed by a typed-buffer-sized <see cref="global::Mockolate.Interactions.FastMockInteractions">FastMockInteractions</see> from <paramref name="behavior" />.
@@ -545,10 +539,10 @@ internal class ComprehensiveAbstractClass :
 
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastMethod0Buffer MockolateBuffer_A
-			=> field ?? (field = (global::Mockolate.Interactions.FastMethod0Buffer)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.ComprehensiveAbstractClass.MemberId_A]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod0Buffer>(global::Mockolate.Mock.ComprehensiveAbstractClass.MemberId_A, static fast => new global::Mockolate.Interactions.FastMethod0Buffer(fast)));
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastMethod0Buffer MockolateBuffer_P
-			=> field ?? (field = (global::Mockolate.Interactions.FastMethod0Buffer)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.ComprehensiveAbstractClass.MemberId_P]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod0Buffer>(global::Mockolate.Mock.ComprehensiveAbstractClass.MemberId_P, static fast => new global::Mockolate.Interactions.FastMethod0Buffer(fast)));
 
 		/// <inheritdoc />
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
diff --git a/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/ComprehensiveInterface_CanBeCreated/Mock.IComprehensiveInterface.g.cs b/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/ComprehensiveInterface_CanBeCreated/Mock.IComprehensiveInterface.g.cs
index 62bb9a3d..7937aae1 100644
--- a/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/ComprehensiveInterface_CanBeCreated/Mock.IComprehensiveInterface.g.cs
+++ b/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/ComprehensiveInterface_CanBeCreated/Mock.IComprehensiveInterface.g.cs
@@ -263,48 +263,10 @@ internal class IComprehensiveInterface :
 
 		/// <summary>
 		///     Creates a <see cref="global::Mockolate.Interactions.FastMockInteractions">FastMockInteractions</see> sized to <see cref="MemberCount">MemberCount</see> for use as the mock's interaction store.
+		///     Per-member buffers are not allocated up-front: the recording hot paths call <see cref="global::Mockolate.Interactions.FastMockInteractions.GetOrCreateBuffer{TBuffer}(int, global::System.Func{global::Mockolate.Interactions.FastMockInteractions, TBuffer})">GetOrCreateBuffer&lt;TBuffer&gt;(int, Func&lt;FastMockInteractions, TBuffer&gt;)</see> so a slot is materialized only when its member is first invoked.
 		/// </summary>
 		internal static global::Mockolate.Interactions.FastMockInteractions CreateFastInteractions(global::Mockolate.MockBehavior behavior)
-		{
-			global::Mockolate.Interactions.FastMockInteractions fast = new global::Mockolate.Interactions.FastMockInteractions(MemberCount, behavior.SkipInteractionRecording);
-			global::Mockolate.Interactions.FastMethodBufferFactory.InstallMethod(fast, global::Mockolate.Mock.IComprehensiveInterface.MemberId_StaticAbstractMethod);
-			global::Mockolate.Interactions.FastMethodBufferFactory.InstallMethod<int, string, long, int[]>(fast, global::Mockolate.Mock.IComprehensiveInterface.MemberId_WithModifiers);
-			fast.InstallBuffer(global::Mockolate.Mock.IComprehensiveInterface.MemberId_WithDefaults, new global::Mockolate.Interactions.FastMethod7Buffer<int, global::Mockolate.Tests.GeneratorCoverage.MyEnum, decimal, float, char, string?, global::Mockolate.Tests.GeneratorCoverage.MyStruct>(fast));
-			fast.InstallBuffer(global::Mockolate.Mock.IComprehensiveInterface.MemberId_WithCollidingNames, new global::Mockolate.Interactions.FastMethod5Buffer<int, int, int, int, int>(fast));
-			global::Mockolate.Interactions.FastMethodBufferFactory.InstallMethod<string?>(fast, global::Mockolate.Mock.IComprehensiveInterface.MemberId_GetMaybeNull);
-			global::Mockolate.Interactions.FastMethodBufferFactory.InstallMethod(fast, global::Mockolate.Mock.IComprehensiveInterface.MemberId_DoTask);
-			global::Mockolate.Interactions.FastMethodBufferFactory.InstallMethod(fast, global::Mockolate.Mock.IComprehensiveInterface.MemberId_DoTaskOf);
-			global::Mockolate.Interactions.FastMethodBufferFactory.InstallMethod(fast, global::Mockolate.Mock.IComprehensiveInterface.MemberId_DoVT);
-			global::Mockolate.Interactions.FastMethodBufferFactory.InstallMethod(fast, global::Mockolate.Mock.IComprehensiveInterface.MemberId_DoVTOf);
-			global::Mockolate.Interactions.FastMethodBufferFactory.InstallMethod(fast, global::Mockolate.Mock.IComprehensiveInterface.MemberId_GetTuple);
-			global::Mockolate.Interactions.FastMethodBufferFactory.InstallMethod(fast, global::Mockolate.Mock.IComprehensiveInterface.MemberId_GetNullable);
-			global::Mockolate.Interactions.FastMethodBufferFactory.InstallMethod<int>(fast, global::Mockolate.Mock.IComprehensiveInterface.MemberId_GetSpan);
-			global::Mockolate.Interactions.FastMethodBufferFactory.InstallMethod<int>(fast, global::Mockolate.Mock.IComprehensiveInterface.MemberId_GetROSpan);
-			global::Mockolate.Interactions.FastMethodBufferFactory.InstallMethod(fast, global::Mockolate.Mock.IComprehensiveInterface.MemberId_GetByRef);
-			global::Mockolate.Interactions.FastMethodBufferFactory.InstallMethod(fast, global::Mockolate.Mock.IComprehensiveInterface.MemberId_GetByRefReadonly);
-			fast.InstallBuffer(global::Mockolate.Mock.IComprehensiveInterface.MemberId_Five, new global::Mockolate.Interactions.FastMethod5Buffer<int, int, int, int, int>(fast));
-			fast.InstallBuffer(global::Mockolate.Mock.IComprehensiveInterface.MemberId_Seventeen, new global::Mockolate.Interactions.FastMethod17Buffer<int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int>(fast));
-			fast.InstallBuffer(global::Mockolate.Mock.IComprehensiveInterface.MemberId_SeventeenVoid, new global::Mockolate.Interactions.FastMethod17Buffer<int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int>(fast));
-			global::Mockolate.Interactions.FastPropertyBufferFactory.InstallPropertyGetter(fast, global::Mockolate.Mock.IComprehensiveInterface.MemberId_GetSet_Get, global::Mockolate.Mock.IComprehensiveInterface.PropertyAccess_GetSet_Get);
-			global::Mockolate.Interactions.FastPropertyBufferFactory.InstallPropertySetter<int>(fast, global::Mockolate.Mock.IComprehensiveInterface.MemberId_GetSet_Set);
-			global::Mockolate.Interactions.FastPropertyBufferFactory.InstallPropertyGetter(fast, global::Mockolate.Mock.IComprehensiveInterface.MemberId_GetOnly_Get, global::Mockolate.Mock.IComprehensiveInterface.PropertyAccess_GetOnly_Get);
-			global::Mockolate.Interactions.FastPropertyBufferFactory.InstallPropertySetter<int>(fast, global::Mockolate.Mock.IComprehensiveInterface.MemberId_GetOnly_Set);
-			global::Mockolate.Interactions.FastPropertyBufferFactory.InstallPropertyGetter(fast, global::Mockolate.Mock.IComprehensiveInterface.MemberId_SetOnly_Get, global::Mockolate.Mock.IComprehensiveInterface.PropertyAccess_SetOnly_Get);
-			global::Mockolate.Interactions.FastPropertyBufferFactory.InstallPropertySetter<int>(fast, global::Mockolate.Mock.IComprehensiveInterface.MemberId_SetOnly_Set);
-			global::Mockolate.Interactions.FastPropertyBufferFactory.InstallPropertyGetter(fast, global::Mockolate.Mock.IComprehensiveInterface.MemberId_NullableProp_Get, global::Mockolate.Mock.IComprehensiveInterface.PropertyAccess_NullableProp_Get);
-			global::Mockolate.Interactions.FastPropertyBufferFactory.InstallPropertySetter<string?>(fast, global::Mockolate.Mock.IComprehensiveInterface.MemberId_NullableProp_Set);
-			global::Mockolate.Interactions.FastPropertyBufferFactory.InstallPropertyGetter(fast, global::Mockolate.Mock.IComprehensiveInterface.MemberId_InitOnly_Get, global::Mockolate.Mock.IComprehensiveInterface.PropertyAccess_InitOnly_Get);
-			global::Mockolate.Interactions.FastPropertyBufferFactory.InstallPropertySetter<string>(fast, global::Mockolate.Mock.IComprehensiveInterface.MemberId_InitOnly_Set);
-			global::Mockolate.Interactions.FastIndexerBufferFactory.InstallIndexerGetter<int>(fast, global::Mockolate.Mock.IComprehensiveInterface.MemberId_Indexer_int_Get);
-			global::Mockolate.Interactions.FastIndexerBufferFactory.InstallIndexerSetter<int, string>(fast, global::Mockolate.Mock.IComprehensiveInterface.MemberId_Indexer_int_Set);
-			global::Mockolate.Interactions.FastEventBufferFactory.InstallEventSubscribe(fast, global::Mockolate.Mock.IComprehensiveInterface.MemberId_PlainEvent_Subscribe);
-			global::Mockolate.Interactions.FastEventBufferFactory.InstallEventUnsubscribe(fast, global::Mockolate.Mock.IComprehensiveInterface.MemberId_PlainEvent_Unsubscribe);
-			global::Mockolate.Interactions.FastEventBufferFactory.InstallEventSubscribe(fast, global::Mockolate.Mock.IComprehensiveInterface.MemberId_TypedEvent_Subscribe);
-			global::Mockolate.Interactions.FastEventBufferFactory.InstallEventUnsubscribe(fast, global::Mockolate.Mock.IComprehensiveInterface.MemberId_TypedEvent_Unsubscribe);
-			global::Mockolate.Interactions.FastEventBufferFactory.InstallEventSubscribe(fast, global::Mockolate.Mock.IComprehensiveInterface.MemberId_CustomEvent_Subscribe);
-			global::Mockolate.Interactions.FastEventBufferFactory.InstallEventUnsubscribe(fast, global::Mockolate.Mock.IComprehensiveInterface.MemberId_CustomEvent_Unsubscribe);
-			return fast;
-		}
+			=> new global::Mockolate.Interactions.FastMockInteractions(MemberCount, behavior.SkipInteractionRecording);
 
 		/// <summary>
 		///     Builds a <see cref="global::Mockolate.MockRegistry">MockRegistry</see> backed by a typed-buffer-sized <see cref="global::Mockolate.Interactions.FastMockInteractions">FastMockInteractions</see> from <paramref name="behavior" />.
@@ -325,61 +287,61 @@ internal class IComprehensiveInterface :
 
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastIndexerGetterBuffer<int> MockolateBuffer_Indexer_int_Get
-			=> field ?? (field = (global::Mockolate.Interactions.FastIndexerGetterBuffer<int>)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.IComprehensiveInterface.MemberId_Indexer_int_Get]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastIndexerGetterBuffer<int>>(global::Mockolate.Mock.IComprehensiveInterface.MemberId_Indexer_int_Get, static fast => new global::Mockolate.Interactions.FastIndexerGetterBuffer<int>(fast)));
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastIndexerSetterBuffer<int, string> MockolateBuffer_Indexer_int_Set
-			=> field ?? (field = (global::Mockolate.Interactions.FastIndexerSetterBuffer<int, string>)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.IComprehensiveInterface.MemberId_Indexer_int_Set]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastIndexerSetterBuffer<int, string>>(global::Mockolate.Mock.IComprehensiveInterface.MemberId_Indexer_int_Set, static fast => new global::Mockolate.Interactions.FastIndexerSetterBuffer<int, string>(fast)));
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastMethod4Buffer<int, string, long, int[]> MockolateBuffer_WithModifiers
-			=> field ?? (field = (global::Mockolate.Interactions.FastMethod4Buffer<int, string, long, int[]>)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.IComprehensiveInterface.MemberId_WithModifiers]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod4Buffer<int, string, long, int[]>>(global::Mockolate.Mock.IComprehensiveInterface.MemberId_WithModifiers, static fast => new global::Mockolate.Interactions.FastMethod4Buffer<int, string, long, int[]>(fast)));
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastMethod7Buffer<int, global::Mockolate.Tests.GeneratorCoverage.MyEnum, decimal, float, char, string?, global::Mockolate.Tests.GeneratorCoverage.MyStruct> MockolateBuffer_WithDefaults
-			=> field ?? (field = (global::Mockolate.Interactions.FastMethod7Buffer<int, global::Mockolate.Tests.GeneratorCoverage.MyEnum, decimal, float, char, string?, global::Mockolate.Tests.GeneratorCoverage.MyStruct>)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.IComprehensiveInterface.MemberId_WithDefaults]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod7Buffer<int, global::Mockolate.Tests.GeneratorCoverage.MyEnum, decimal, float, char, string?, global::Mockolate.Tests.GeneratorCoverage.MyStruct>>(global::Mockolate.Mock.IComprehensiveInterface.MemberId_WithDefaults, static fast => new global::Mockolate.Interactions.FastMethod7Buffer<int, global::Mockolate.Tests.GeneratorCoverage.MyEnum, decimal, float, char, string?, global::Mockolate.Tests.GeneratorCoverage.MyStruct>(fast)));
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastMethod5Buffer<int, int, int, int, int> MockolateBuffer_WithCollidingNames
-			=> field ?? (field = (global::Mockolate.Interactions.FastMethod5Buffer<int, int, int, int, int>)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.IComprehensiveInterface.MemberId_WithCollidingNames]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod5Buffer<int, int, int, int, int>>(global::Mockolate.Mock.IComprehensiveInterface.MemberId_WithCollidingNames, static fast => new global::Mockolate.Interactions.FastMethod5Buffer<int, int, int, int, int>(fast)));
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastMethod1Buffer<string?> MockolateBuffer_GetMaybeNull
-			=> field ?? (field = (global::Mockolate.Interactions.FastMethod1Buffer<string?>)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.IComprehensiveInterface.MemberId_GetMaybeNull]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod1Buffer<string?>>(global::Mockolate.Mock.IComprehensiveInterface.MemberId_GetMaybeNull, static fast => new global::Mockolate.Interactions.FastMethod1Buffer<string?>(fast)));
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastMethod0Buffer MockolateBuffer_DoTask
-			=> field ?? (field = (global::Mockolate.Interactions.FastMethod0Buffer)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.IComprehensiveInterface.MemberId_DoTask]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod0Buffer>(global::Mockolate.Mock.IComprehensiveInterface.MemberId_DoTask, static fast => new global::Mockolate.Interactions.FastMethod0Buffer(fast)));
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastMethod0Buffer MockolateBuffer_DoTaskOf
-			=> field ?? (field = (global::Mockolate.Interactions.FastMethod0Buffer)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.IComprehensiveInterface.MemberId_DoTaskOf]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod0Buffer>(global::Mockolate.Mock.IComprehensiveInterface.MemberId_DoTaskOf, static fast => new global::Mockolate.Interactions.FastMethod0Buffer(fast)));
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastMethod0Buffer MockolateBuffer_DoVT
-			=> field ?? (field = (global::Mockolate.Interactions.FastMethod0Buffer)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.IComprehensiveInterface.MemberId_DoVT]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod0Buffer>(global::Mockolate.Mock.IComprehensiveInterface.MemberId_DoVT, static fast => new global::Mockolate.Interactions.FastMethod0Buffer(fast)));
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastMethod0Buffer MockolateBuffer_DoVTOf
-			=> field ?? (field = (global::Mockolate.Interactions.FastMethod0Buffer)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.IComprehensiveInterface.MemberId_DoVTOf]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod0Buffer>(global::Mockolate.Mock.IComprehensiveInterface.MemberId_DoVTOf, static fast => new global::Mockolate.Interactions.FastMethod0Buffer(fast)));
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastMethod0Buffer MockolateBuffer_GetTuple
-			=> field ?? (field = (global::Mockolate.Interactions.FastMethod0Buffer)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.IComprehensiveInterface.MemberId_GetTuple]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod0Buffer>(global::Mockolate.Mock.IComprehensiveInterface.MemberId_GetTuple, static fast => new global::Mockolate.Interactions.FastMethod0Buffer(fast)));
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastMethod0Buffer MockolateBuffer_GetNullable
-			=> field ?? (field = (global::Mockolate.Interactions.FastMethod0Buffer)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.IComprehensiveInterface.MemberId_GetNullable]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod0Buffer>(global::Mockolate.Mock.IComprehensiveInterface.MemberId_GetNullable, static fast => new global::Mockolate.Interactions.FastMethod0Buffer(fast)));
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastMethod1Buffer<int> MockolateBuffer_GetSpan
-			=> field ?? (field = (global::Mockolate.Interactions.FastMethod1Buffer<int>)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.IComprehensiveInterface.MemberId_GetSpan]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod1Buffer<int>>(global::Mockolate.Mock.IComprehensiveInterface.MemberId_GetSpan, static fast => new global::Mockolate.Interactions.FastMethod1Buffer<int>(fast)));
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastMethod1Buffer<int> MockolateBuffer_GetROSpan
-			=> field ?? (field = (global::Mockolate.Interactions.FastMethod1Buffer<int>)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.IComprehensiveInterface.MemberId_GetROSpan]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod1Buffer<int>>(global::Mockolate.Mock.IComprehensiveInterface.MemberId_GetROSpan, static fast => new global::Mockolate.Interactions.FastMethod1Buffer<int>(fast)));
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastMethod0Buffer MockolateBuffer_GetByRef
-			=> field ?? (field = (global::Mockolate.Interactions.FastMethod0Buffer)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.IComprehensiveInterface.MemberId_GetByRef]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod0Buffer>(global::Mockolate.Mock.IComprehensiveInterface.MemberId_GetByRef, static fast => new global::Mockolate.Interactions.FastMethod0Buffer(fast)));
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastMethod0Buffer MockolateBuffer_GetByRefReadonly
-			=> field ?? (field = (global::Mockolate.Interactions.FastMethod0Buffer)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.IComprehensiveInterface.MemberId_GetByRefReadonly]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod0Buffer>(global::Mockolate.Mock.IComprehensiveInterface.MemberId_GetByRefReadonly, static fast => new global::Mockolate.Interactions.FastMethod0Buffer(fast)));
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastMethod5Buffer<int, int, int, int, int> MockolateBuffer_Five
-			=> field ?? (field = (global::Mockolate.Interactions.FastMethod5Buffer<int, int, int, int, int>)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.IComprehensiveInterface.MemberId_Five]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod5Buffer<int, int, int, int, int>>(global::Mockolate.Mock.IComprehensiveInterface.MemberId_Five, static fast => new global::Mockolate.Interactions.FastMethod5Buffer<int, int, int, int, int>(fast)));
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastMethod17Buffer<int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int> MockolateBuffer_Seventeen
-			=> field ?? (field = (global::Mockolate.Interactions.FastMethod17Buffer<int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int>)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.IComprehensiveInterface.MemberId_Seventeen]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod17Buffer<int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int>>(global::Mockolate.Mock.IComprehensiveInterface.MemberId_Seventeen, static fast => new global::Mockolate.Interactions.FastMethod17Buffer<int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int>(fast)));
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastMethod17Buffer<int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int> MockolateBuffer_SeventeenVoid
-			=> field ?? (field = (global::Mockolate.Interactions.FastMethod17Buffer<int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int>)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.IComprehensiveInterface.MemberId_SeventeenVoid]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod17Buffer<int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int>>(global::Mockolate.Mock.IComprehensiveInterface.MemberId_SeventeenVoid, static fast => new global::Mockolate.Interactions.FastMethod17Buffer<int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int>(fast)));
 
 		/// <inheritdoc />
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
@@ -759,7 +721,7 @@ public static int StaticAbstractMethod()
 			int wrappedResult = default!;
 			if (MockRegistryProvider.Value.Behavior.SkipInteractionRecording == false)
 			{
-				((global::Mockolate.Interactions.FastMethod0Buffer)((global::Mockolate.Interactions.FastMockInteractions)MockRegistryProvider.Value.Interactions).Buffers[global::Mockolate.Mock.IComprehensiveInterface.MemberId_StaticAbstractMethod]!).Append("global::Mockolate.Tests.GeneratorCoverage.IComprehensiveInterface.StaticAbstractMethod");
+				((global::Mockolate.Interactions.FastMockInteractions)MockRegistryProvider.Value.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod0Buffer>(global::Mockolate.Mock.IComprehensiveInterface.MemberId_StaticAbstractMethod, static fast => new global::Mockolate.Interactions.FastMethod0Buffer(fast)).Append("global::Mockolate.Tests.GeneratorCoverage.IComprehensiveInterface.StaticAbstractMethod");
 			}
 			try
 			{
diff --git a/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/HttpClient_CanBeCreated/Mock.HttpClient.g.cs b/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/HttpClient_CanBeCreated/Mock.HttpClient.g.cs
index 6b299f02..e3384700 100644
--- a/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/HttpClient_CanBeCreated/Mock.HttpClient.g.cs
+++ b/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/HttpClient_CanBeCreated/Mock.HttpClient.g.cs
@@ -529,15 +529,10 @@ internal class HttpClient :
 
 		/// <summary>
 		///     Creates a <see cref="global::Mockolate.Interactions.FastMockInteractions">FastMockInteractions</see> sized to <see cref="MemberCount">MemberCount</see> for use as the mock's interaction store.
+		///     Per-member buffers are not allocated up-front: the recording hot paths call <see cref="global::Mockolate.Interactions.FastMockInteractions.GetOrCreateBuffer{TBuffer}(int, global::System.Func{global::Mockolate.Interactions.FastMockInteractions, TBuffer})">GetOrCreateBuffer&lt;TBuffer&gt;(int, Func&lt;FastMockInteractions, TBuffer&gt;)</see> so a slot is materialized only when its member is first invoked.
 		/// </summary>
 		internal static global::Mockolate.Interactions.FastMockInteractions CreateFastInteractions(global::Mockolate.MockBehavior behavior)
-		{
-			global::Mockolate.Interactions.FastMockInteractions fast = new global::Mockolate.Interactions.FastMockInteractions(MemberCount, behavior.SkipInteractionRecording);
-			global::Mockolate.Interactions.FastMethodBufferFactory.InstallMethod<global::System.Net.Http.HttpRequestMessage, global::System.Threading.CancellationToken>(fast, global::Mockolate.Mock.HttpClient.MemberId_Send);
-			global::Mockolate.Interactions.FastMethodBufferFactory.InstallMethod<global::System.Net.Http.HttpRequestMessage, global::System.Threading.CancellationToken>(fast, global::Mockolate.Mock.HttpClient.MemberId_SendAsync);
-			global::Mockolate.Interactions.FastMethodBufferFactory.InstallMethod<bool>(fast, global::Mockolate.Mock.HttpClient.MemberId_Dispose);
-			return fast;
-		}
+			=> new global::Mockolate.Interactions.FastMockInteractions(MemberCount, behavior.SkipInteractionRecording);
 
 		/// <summary>
 		///     Builds a <see cref="global::Mockolate.MockRegistry">MockRegistry</see> backed by a typed-buffer-sized <see cref="global::Mockolate.Interactions.FastMockInteractions">FastMockInteractions</see> from <paramref name="behavior" />.
@@ -562,13 +557,13 @@ internal class HttpClient :
 
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastMethod2Buffer<global::System.Net.Http.HttpRequestMessage, global::System.Threading.CancellationToken> MockolateBuffer_Send
-			=> field ?? (field = (global::Mockolate.Interactions.FastMethod2Buffer<global::System.Net.Http.HttpRequestMessage, global::System.Threading.CancellationToken>)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.HttpClient.MemberId_Send]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod2Buffer<global::System.Net.Http.HttpRequestMessage, global::System.Threading.CancellationToken>>(global::Mockolate.Mock.HttpClient.MemberId_Send, static fast => new global::Mockolate.Interactions.FastMethod2Buffer<global::System.Net.Http.HttpRequestMessage, global::System.Threading.CancellationToken>(fast)));
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastMethod2Buffer<global::System.Net.Http.HttpRequestMessage, global::System.Threading.CancellationToken> MockolateBuffer_SendAsync
-			=> field ?? (field = (global::Mockolate.Interactions.FastMethod2Buffer<global::System.Net.Http.HttpRequestMessage, global::System.Threading.CancellationToken>)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.HttpClient.MemberId_SendAsync]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod2Buffer<global::System.Net.Http.HttpRequestMessage, global::System.Threading.CancellationToken>>(global::Mockolate.Mock.HttpClient.MemberId_SendAsync, static fast => new global::Mockolate.Interactions.FastMethod2Buffer<global::System.Net.Http.HttpRequestMessage, global::System.Threading.CancellationToken>(fast)));
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastMethod1Buffer<bool> MockolateBuffer_Dispose
-			=> field ?? (field = (global::Mockolate.Interactions.FastMethod1Buffer<bool>)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.HttpClient.MemberId_Dispose]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod1Buffer<bool>>(global::Mockolate.Mock.HttpClient.MemberId_Dispose, static fast => new global::Mockolate.Interactions.FastMethod1Buffer<bool>(fast)));
 
 		/// <inheritdoc />
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
diff --git a/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/HttpClient_CanBeCreated/Mock.HttpMessageHandler.g.cs b/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/HttpClient_CanBeCreated/Mock.HttpMessageHandler.g.cs
index e1c8d49d..22c0dc0c 100644
--- a/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/HttpClient_CanBeCreated/Mock.HttpMessageHandler.g.cs
+++ b/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/HttpClient_CanBeCreated/Mock.HttpMessageHandler.g.cs
@@ -361,15 +361,10 @@ internal class HttpMessageHandler :
 
 		/// <summary>
 		///     Creates a <see cref="global::Mockolate.Interactions.FastMockInteractions">FastMockInteractions</see> sized to <see cref="MemberCount">MemberCount</see> for use as the mock's interaction store.
+		///     Per-member buffers are not allocated up-front: the recording hot paths call <see cref="global::Mockolate.Interactions.FastMockInteractions.GetOrCreateBuffer{TBuffer}(int, global::System.Func{global::Mockolate.Interactions.FastMockInteractions, TBuffer})">GetOrCreateBuffer&lt;TBuffer&gt;(int, Func&lt;FastMockInteractions, TBuffer&gt;)</see> so a slot is materialized only when its member is first invoked.
 		/// </summary>
 		internal static global::Mockolate.Interactions.FastMockInteractions CreateFastInteractions(global::Mockolate.MockBehavior behavior)
-		{
-			global::Mockolate.Interactions.FastMockInteractions fast = new global::Mockolate.Interactions.FastMockInteractions(MemberCount, behavior.SkipInteractionRecording);
-			global::Mockolate.Interactions.FastMethodBufferFactory.InstallMethod<global::System.Net.Http.HttpRequestMessage, global::System.Threading.CancellationToken>(fast, global::Mockolate.Mock.HttpMessageHandler.MemberId_Send);
-			global::Mockolate.Interactions.FastMethodBufferFactory.InstallMethod<global::System.Net.Http.HttpRequestMessage, global::System.Threading.CancellationToken>(fast, global::Mockolate.Mock.HttpMessageHandler.MemberId_SendAsync);
-			global::Mockolate.Interactions.FastMethodBufferFactory.InstallMethod<bool>(fast, global::Mockolate.Mock.HttpMessageHandler.MemberId_Dispose);
-			return fast;
-		}
+			=> new global::Mockolate.Interactions.FastMockInteractions(MemberCount, behavior.SkipInteractionRecording);
 
 		/// <summary>
 		///     Builds a <see cref="global::Mockolate.MockRegistry">MockRegistry</see> backed by a typed-buffer-sized <see cref="global::Mockolate.Interactions.FastMockInteractions">FastMockInteractions</see> from <paramref name="behavior" />.
@@ -394,13 +389,13 @@ internal class HttpMessageHandler :
 
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastMethod2Buffer<global::System.Net.Http.HttpRequestMessage, global::System.Threading.CancellationToken> MockolateBuffer_Send
-			=> field ?? (field = (global::Mockolate.Interactions.FastMethod2Buffer<global::System.Net.Http.HttpRequestMessage, global::System.Threading.CancellationToken>)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.HttpMessageHandler.MemberId_Send]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod2Buffer<global::System.Net.Http.HttpRequestMessage, global::System.Threading.CancellationToken>>(global::Mockolate.Mock.HttpMessageHandler.MemberId_Send, static fast => new global::Mockolate.Interactions.FastMethod2Buffer<global::System.Net.Http.HttpRequestMessage, global::System.Threading.CancellationToken>(fast)));
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastMethod2Buffer<global::System.Net.Http.HttpRequestMessage, global::System.Threading.CancellationToken> MockolateBuffer_SendAsync
-			=> field ?? (field = (global::Mockolate.Interactions.FastMethod2Buffer<global::System.Net.Http.HttpRequestMessage, global::System.Threading.CancellationToken>)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.HttpMessageHandler.MemberId_SendAsync]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod2Buffer<global::System.Net.Http.HttpRequestMessage, global::System.Threading.CancellationToken>>(global::Mockolate.Mock.HttpMessageHandler.MemberId_SendAsync, static fast => new global::Mockolate.Interactions.FastMethod2Buffer<global::System.Net.Http.HttpRequestMessage, global::System.Threading.CancellationToken>(fast)));
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastMethod1Buffer<bool> MockolateBuffer_Dispose
-			=> field ?? (field = (global::Mockolate.Interactions.FastMethod1Buffer<bool>)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.HttpMessageHandler.MemberId_Dispose]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod1Buffer<bool>>(global::Mockolate.Mock.HttpMessageHandler.MemberId_Dispose, static fast => new global::Mockolate.Interactions.FastMethod1Buffer<bool>(fast)));
 
 		/// <inheritdoc />
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
diff --git a/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/KeywordEdgeCases_CanBeCreated/Mock.IKeywordEdgeCases.g.cs b/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/KeywordEdgeCases_CanBeCreated/Mock.IKeywordEdgeCases.g.cs
index 7ddf1dc1..5d66fe61 100644
--- a/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/KeywordEdgeCases_CanBeCreated/Mock.IKeywordEdgeCases.g.cs
+++ b/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/KeywordEdgeCases_CanBeCreated/Mock.IKeywordEdgeCases.g.cs
@@ -218,20 +218,10 @@ internal class IKeywordEdgeCases :
 
 		/// <summary>
 		///     Creates a <see cref="global::Mockolate.Interactions.FastMockInteractions">FastMockInteractions</see> sized to <see cref="MemberCount">MemberCount</see> for use as the mock's interaction store.
+		///     Per-member buffers are not allocated up-front: the recording hot paths call <see cref="global::Mockolate.Interactions.FastMockInteractions.GetOrCreateBuffer{TBuffer}(int, global::System.Func{global::Mockolate.Interactions.FastMockInteractions, TBuffer})">GetOrCreateBuffer&lt;TBuffer&gt;(int, Func&lt;FastMockInteractions, TBuffer&gt;)</see> so a slot is materialized only when its member is first invoked.
 		/// </summary>
 		internal static global::Mockolate.Interactions.FastMockInteractions CreateFastInteractions(global::Mockolate.MockBehavior behavior)
-		{
-			global::Mockolate.Interactions.FastMockInteractions fast = new global::Mockolate.Interactions.FastMockInteractions(MemberCount, behavior.SkipInteractionRecording);
-			global::Mockolate.Interactions.FastMethodBufferFactory.InstallMethod(fast, global::Mockolate.Mock.IKeywordEdgeCases.MemberId__return);
-			global::Mockolate.Interactions.FastMethodBufferFactory.InstallMethod<int>(fast, global::Mockolate.Mock.IKeywordEdgeCases.MemberId__if);
-			global::Mockolate.Interactions.FastPropertyBufferFactory.InstallPropertyGetter(fast, global::Mockolate.Mock.IKeywordEdgeCases.MemberId__class_Get, global::Mockolate.Mock.IKeywordEdgeCases.PropertyAccess__class_Get);
-			global::Mockolate.Interactions.FastPropertyBufferFactory.InstallPropertySetter<int>(fast, global::Mockolate.Mock.IKeywordEdgeCases.MemberId__class_Set);
-			global::Mockolate.Interactions.FastIndexerBufferFactory.InstallIndexerGetter<int, string>(fast, global::Mockolate.Mock.IKeywordEdgeCases.MemberId_Indexer_int_string_Get);
-			global::Mockolate.Interactions.FastIndexerBufferFactory.InstallIndexerSetter<int, string, string>(fast, global::Mockolate.Mock.IKeywordEdgeCases.MemberId_Indexer_int_string_Set);
-			global::Mockolate.Interactions.FastEventBufferFactory.InstallEventSubscribe(fast, global::Mockolate.Mock.IKeywordEdgeCases.MemberId__event_Subscribe);
-			global::Mockolate.Interactions.FastEventBufferFactory.InstallEventUnsubscribe(fast, global::Mockolate.Mock.IKeywordEdgeCases.MemberId__event_Unsubscribe);
-			return fast;
-		}
+			=> new global::Mockolate.Interactions.FastMockInteractions(MemberCount, behavior.SkipInteractionRecording);
 
 		/// <summary>
 		///     Builds a <see cref="global::Mockolate.MockRegistry">MockRegistry</see> backed by a typed-buffer-sized <see cref="global::Mockolate.Interactions.FastMockInteractions">FastMockInteractions</see> from <paramref name="behavior" />.
@@ -249,16 +239,16 @@ internal class IKeywordEdgeCases :
 
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastIndexerGetterBuffer<int, string> MockolateBuffer_Indexer_int_string_Get
-			=> field ?? (field = (global::Mockolate.Interactions.FastIndexerGetterBuffer<int, string>)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.IKeywordEdgeCases.MemberId_Indexer_int_string_Get]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastIndexerGetterBuffer<int, string>>(global::Mockolate.Mock.IKeywordEdgeCases.MemberId_Indexer_int_string_Get, static fast => new global::Mockolate.Interactions.FastIndexerGetterBuffer<int, string>(fast)));
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastIndexerSetterBuffer<int, string, string> MockolateBuffer_Indexer_int_string_Set
-			=> field ?? (field = (global::Mockolate.Interactions.FastIndexerSetterBuffer<int, string, string>)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.IKeywordEdgeCases.MemberId_Indexer_int_string_Set]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastIndexerSetterBuffer<int, string, string>>(global::Mockolate.Mock.IKeywordEdgeCases.MemberId_Indexer_int_string_Set, static fast => new global::Mockolate.Interactions.FastIndexerSetterBuffer<int, string, string>(fast)));
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastMethod0Buffer MockolateBuffer__return
-			=> field ?? (field = (global::Mockolate.Interactions.FastMethod0Buffer)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.IKeywordEdgeCases.MemberId__return]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod0Buffer>(global::Mockolate.Mock.IKeywordEdgeCases.MemberId__return, static fast => new global::Mockolate.Interactions.FastMethod0Buffer(fast)));
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
 		private global::Mockolate.Interactions.FastMethod1Buffer<int> MockolateBuffer__if
-			=> field ?? (field = (global::Mockolate.Interactions.FastMethod1Buffer<int>)((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).Buffers[global::Mockolate.Mock.IKeywordEdgeCases.MemberId__if]!);
+			=> field ?? (field = ((global::Mockolate.Interactions.FastMockInteractions)this.MockRegistry.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod1Buffer<int>>(global::Mockolate.Mock.IKeywordEdgeCases.MemberId__if, static fast => new global::Mockolate.Interactions.FastMethod1Buffer<int>(fast)));
 
 		/// <inheritdoc />
 		[global::System.Diagnostics.DebuggerBrowsable(global::System.Diagnostics.DebuggerBrowsableState.Never)]
diff --git a/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/RefStructConsumer_CanBeCreated/Mock.IRefStructConsumer.g.cs b/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/RefStructConsumer_CanBeCreated/Mock.IRefStructConsumer.g.cs
index 6ae671f2..a9a3e5a6 100644
--- a/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/RefStructConsumer_CanBeCreated/Mock.IRefStructConsumer.g.cs
+++ b/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/RefStructConsumer_CanBeCreated/Mock.IRefStructConsumer.g.cs
@@ -209,12 +209,10 @@ internal class IRefStructConsumer :
 
 		/// <summary>
 		///     Creates a <see cref="global::Mockolate.Interactions.FastMockInteractions">FastMockInteractions</see> sized to <see cref="MemberCount">MemberCount</see> for use as the mock's interaction store.
+		///     Per-member buffers are not allocated up-front: the recording hot paths call <see cref="global::Mockolate.Interactions.FastMockInteractions.GetOrCreateBuffer{TBuffer}(int, global::System.Func{global::Mockolate.Interactions.FastMockInteractions, TBuffer})">GetOrCreateBuffer&lt;TBuffer&gt;(int, Func&lt;FastMockInteractions, TBuffer&gt;)</see> so a slot is materialized only when its member is first invoked.
 		/// </summary>
 		internal static global::Mockolate.Interactions.FastMockInteractions CreateFastInteractions(global::Mockolate.MockBehavior behavior)
-		{
-			global::Mockolate.Interactions.FastMockInteractions fast = new global::Mockolate.Interactions.FastMockInteractions(MemberCount, behavior.SkipInteractionRecording);
-			return fast;
-		}
+			=> new global::Mockolate.Interactions.FastMockInteractions(MemberCount, behavior.SkipInteractionRecording);
 
 		/// <summary>
 		///     Builds a <see cref="global::Mockolate.MockRegistry">MockRegistry</see> backed by a typed-buffer-sized <see cref="global::Mockolate.Interactions.FastMockInteractions">FastMockInteractions</see> from <paramref name="behavior" />.
diff --git a/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/StaticAbstractMembers_CanBeCreated/Mock.IStaticAbstractMembers.g.cs b/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/StaticAbstractMembers_CanBeCreated/Mock.IStaticAbstractMembers.g.cs
index d0442cfa..e0a26c5e 100644
--- a/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/StaticAbstractMembers_CanBeCreated/Mock.IStaticAbstractMembers.g.cs
+++ b/Tests/Mockolate.SourceGenerators.Tests/Snapshot/Expected/StaticAbstractMembers_CanBeCreated/Mock.IStaticAbstractMembers.g.cs
@@ -217,14 +217,10 @@ internal class IStaticAbstractMembers :
 
 		/// <summary>
 		///     Creates a <see cref="global::Mockolate.Interactions.FastMockInteractions">FastMockInteractions</see> sized to <see cref="MemberCount">MemberCount</see> for use as the mock's interaction store.
+		///     Per-member buffers are not allocated up-front: the recording hot paths call <see cref="global::Mockolate.Interactions.FastMockInteractions.GetOrCreateBuffer{TBuffer}(int, global::System.Func{global::Mockolate.Interactions.FastMockInteractions, TBuffer})">GetOrCreateBuffer&lt;TBuffer&gt;(int, Func&lt;FastMockInteractions, TBuffer&gt;)</see> so a slot is materialized only when its member is first invoked.
 		/// </summary>
 		internal static global::Mockolate.Interactions.FastMockInteractions CreateFastInteractions(global::Mockolate.MockBehavior behavior)
-		{
-			global::Mockolate.Interactions.FastMockInteractions fast = new global::Mockolate.Interactions.FastMockInteractions(MemberCount, behavior.SkipInteractionRecording);
-			global::Mockolate.Interactions.FastMethodBufferFactory.InstallMethod(fast, global::Mockolate.Mock.IStaticAbstractMembers.MemberId_AbstractStaticMethod);
-			global::Mockolate.Interactions.FastMethodBufferFactory.InstallMethod(fast, global::Mockolate.Mock.IStaticAbstractMembers.MemberId_VirtualStaticMethod);
-			return fast;
-		}
+			=> new global::Mockolate.Interactions.FastMockInteractions(MemberCount, behavior.SkipInteractionRecording);
 
 		/// <summary>
 		///     Builds a <see cref="global::Mockolate.MockRegistry">MockRegistry</see> backed by a typed-buffer-sized <see cref="global::Mockolate.Interactions.FastMockInteractions">FastMockInteractions</see> from <paramref name="behavior" />.
@@ -394,7 +390,7 @@ public static int AbstractStaticMethod()
 			int wrappedResult = default!;
 			if (MockRegistryProvider.Value.Behavior.SkipInteractionRecording == false)
 			{
-				((global::Mockolate.Interactions.FastMethod0Buffer)((global::Mockolate.Interactions.FastMockInteractions)MockRegistryProvider.Value.Interactions).Buffers[global::Mockolate.Mock.IStaticAbstractMembers.MemberId_AbstractStaticMethod]!).Append("global::Mockolate.Tests.GeneratorCoverage.IStaticAbstractMembers.AbstractStaticMethod");
+				((global::Mockolate.Interactions.FastMockInteractions)MockRegistryProvider.Value.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod0Buffer>(global::Mockolate.Mock.IStaticAbstractMembers.MemberId_AbstractStaticMethod, static fast => new global::Mockolate.Interactions.FastMethod0Buffer(fast)).Append("global::Mockolate.Tests.GeneratorCoverage.IStaticAbstractMembers.AbstractStaticMethod");
 			}
 			try
 			{
@@ -448,7 +444,7 @@ public static int VirtualStaticMethod()
 			int wrappedResult = default!;
 			if (MockRegistryProvider.Value.Behavior.SkipInteractionRecording == false)
 			{
-				((global::Mockolate.Interactions.FastMethod0Buffer)((global::Mockolate.Interactions.FastMockInteractions)MockRegistryProvider.Value.Interactions).Buffers[global::Mockolate.Mock.IStaticAbstractMembers.MemberId_VirtualStaticMethod]!).Append("global::Mockolate.Tests.GeneratorCoverage.IStaticAbstractMembers.VirtualStaticMethod");
+				((global::Mockolate.Interactions.FastMockInteractions)MockRegistryProvider.Value.Interactions).GetOrCreateBuffer<global::Mockolate.Interactions.FastMethod0Buffer>(global::Mockolate.Mock.IStaticAbstractMembers.MemberId_VirtualStaticMethod, static fast => new global::Mockolate.Interactions.FastMethod0Buffer(fast)).Append("global::Mockolate.Tests.GeneratorCoverage.IStaticAbstractMembers.VirtualStaticMethod");
 			}
 			try
 			{
diff --git a/Tests/Mockolate.Tests/Verify/MockRegistryVerifyTests.cs b/Tests/Mockolate.Tests/Verify/MockRegistryVerifyTests.cs
index a345ecc7..bd899107 100644
--- a/Tests/Mockolate.Tests/Verify/MockRegistryVerifyTests.cs
+++ b/Tests/Mockolate.Tests/Verify/MockRegistryVerifyTests.cs
@@ -12,7 +12,8 @@ public sealed class FailureMessageTests
 		public async Task IndexerGotTyped_FourKeys_FailureMessageIncludesGotIndexerPrefix()
 		{
 			FastMockInteractions store = new(1);
-			store.InstallIndexerGetter<int, string, bool, double>(0);
+			store.GetOrCreateBuffer<FastIndexerGetterBuffer<int, string, bool, double>>(0,
+				static f => new FastIndexerGetterBuffer<int, string, bool, double>(f));
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			void Act()
@@ -33,7 +34,8 @@ await That(Act).Throws<MockVerificationException>()
 		public async Task IndexerGotTyped_OneKey_FailureMessageIncludesGotIndexerPrefix()
 		{
 			FastMockInteractions store = new(1);
-			store.InstallIndexerGetter<int>(0);
+			store.GetOrCreateBuffer<FastIndexerGetterBuffer<int>>(0,
+				static f => new FastIndexerGetterBuffer<int>(f));
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			void Act()
@@ -51,7 +53,8 @@ await That(Act).Throws<MockVerificationException>()
 		public async Task IndexerGotTyped_ThreeKeys_FailureMessageIncludesGotIndexerPrefix()
 		{
 			FastMockInteractions store = new(1);
-			store.InstallIndexerGetter<int, string, bool>(0);
+			store.GetOrCreateBuffer<FastIndexerGetterBuffer<int, string, bool>>(0,
+				static f => new FastIndexerGetterBuffer<int, string, bool>(f));
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			void Act()
@@ -71,7 +74,8 @@ await That(Act).Throws<MockVerificationException>()
 		public async Task IndexerGotTyped_TwoKeys_FailureMessageIncludesGotIndexerPrefix()
 		{
 			FastMockInteractions store = new(1);
-			store.InstallIndexerGetter<int, string>(0);
+			store.GetOrCreateBuffer<FastIndexerGetterBuffer<int, string>>(0,
+				static f => new FastIndexerGetterBuffer<int, string>(f));
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			void Act()
@@ -90,7 +94,8 @@ await That(Act).Throws<MockVerificationException>()
 		public async Task IndexerSetTyped_FourKeys_FailureMessageIncludesSetIndexerPrefix()
 		{
 			FastMockInteractions store = new(1);
-			store.InstallIndexerSetter<int, string, bool, double, char>(0);
+			store.GetOrCreateBuffer<FastIndexerSetterBuffer<int, string, bool, double, char>>(0,
+				static f => new FastIndexerSetterBuffer<int, string, bool, double, char>(f));
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			void Act()
@@ -112,7 +117,8 @@ await That(Act).Throws<MockVerificationException>()
 		public async Task IndexerSetTyped_OneKey_FailureMessageIncludesSetIndexerPrefix()
 		{
 			FastMockInteractions store = new(1);
-			store.InstallIndexerSetter<int, string>(0);
+			store.GetOrCreateBuffer<FastIndexerSetterBuffer<int, string>>(0,
+				static f => new FastIndexerSetterBuffer<int, string>(f));
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			void Act()
@@ -131,7 +137,8 @@ await That(Act).Throws<MockVerificationException>()
 		public async Task IndexerSetTyped_ThreeKeys_FailureMessageIncludesSetIndexerPrefix()
 		{
 			FastMockInteractions store = new(1);
-			store.InstallIndexerSetter<int, string, bool, double>(0);
+			store.GetOrCreateBuffer<FastIndexerSetterBuffer<int, string, bool, double>>(0,
+				static f => new FastIndexerSetterBuffer<int, string, bool, double>(f));
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			void Act()
@@ -152,7 +159,8 @@ await That(Act).Throws<MockVerificationException>()
 		public async Task IndexerSetTyped_TwoKeys_FailureMessageIncludesSetIndexerPrefix()
 		{
 			FastMockInteractions store = new(1);
-			store.InstallIndexerSetter<int, string, bool>(0);
+			store.GetOrCreateBuffer<FastIndexerSetterBuffer<int, string, bool>>(0,
+				static f => new FastIndexerSetterBuffer<int, string, bool>(f));
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			void Act()
@@ -172,7 +180,8 @@ await That(Act).Throws<MockVerificationException>()
 		public async Task SubscribedToTyped_FailureMessageIncludesSubscribedToEventPrefix()
 		{
 			FastMockInteractions store = new(1);
-			store.InstallEventSubscribe(0);
+			store.GetOrCreateBuffer<FastEventBuffer>(0,
+				static f => new FastEventBuffer(f, FastEventBufferKind.Subscribe));
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			void Act()
@@ -188,7 +197,8 @@ await That(Act).Throws<MockVerificationException>()
 		public async Task UnsubscribedFromTyped_FailureMessageIncludesUnsubscribedFromEventPrefix()
 		{
 			FastMockInteractions store = new(1);
-			store.InstallEventUnsubscribe(0);
+			store.GetOrCreateBuffer<FastEventBuffer>(0,
+				static f => new FastEventBuffer(f, FastEventBufferKind.Unsubscribe));
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			void Act()
@@ -204,7 +214,8 @@ await That(Act).Throws<MockVerificationException>()
 		public async Task VerifyMethodTyped_FourParameters_FailureMessageIncludesInvokedMethodPrefix()
 		{
 			FastMockInteractions store = new(1);
-			store.InstallMethod<int, string, bool, double>(0);
+			store.GetOrCreateBuffer<FastMethod4Buffer<int, string, bool, double>>(0,
+				static f => new FastMethod4Buffer<int, string, bool, double>(f));
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			void Act()
@@ -225,7 +236,8 @@ await That(Act).Throws<MockVerificationException>()
 		public async Task VerifyMethodTyped_OneParameter_FailureMessageIncludesInvokedMethodPrefix()
 		{
 			FastMockInteractions store = new(1);
-			store.InstallMethod<int>(0);
+			store.GetOrCreateBuffer<FastMethod1Buffer<int>>(0,
+				static f => new FastMethod1Buffer<int>(f));
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			void Act()
@@ -243,7 +255,8 @@ await That(Act).Throws<MockVerificationException>()
 		public async Task VerifyMethodTyped_Parameterless_FailureMessageIncludesInvokedMethodPrefix()
 		{
 			FastMockInteractions store = new(1);
-			store.InstallMethod(0);
+			store.GetOrCreateBuffer<FastMethod0Buffer>(0,
+				static f => new FastMethod0Buffer(f));
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			void Act()
@@ -259,7 +272,8 @@ await That(Act).Throws<MockVerificationException>()
 		public async Task VerifyMethodTyped_ThreeParameters_FailureMessageIncludesInvokedMethodPrefix()
 		{
 			FastMockInteractions store = new(1);
-			store.InstallMethod<int, string, bool>(0);
+			store.GetOrCreateBuffer<FastMethod3Buffer<int, string, bool>>(0,
+				static f => new FastMethod3Buffer<int, string, bool>(f));
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			void Act()
@@ -279,7 +293,8 @@ await That(Act).Throws<MockVerificationException>()
 		public async Task VerifyMethodTyped_TwoParameters_FailureMessageIncludesInvokedMethodPrefix()
 		{
 			FastMockInteractions store = new(1);
-			store.InstallMethod<int, string>(0);
+			store.GetOrCreateBuffer<FastMethod2Buffer<int, string>>(0,
+				static f => new FastMethod2Buffer<int, string>(f));
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			void Act()
@@ -298,7 +313,8 @@ await That(Act).Throws<MockVerificationException>()
 		public async Task VerifyPropertyTyped_Getter_FailureMessageIncludesGotPropertyPrefix()
 		{
 			FastMockInteractions store = new(1);
-			store.InstallPropertyGetter(0);
+			store.GetOrCreateBuffer<FastPropertyGetterBuffer>(0,
+				static f => new FastPropertyGetterBuffer(f, new PropertyGetterAccess(string.Empty)));
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			void Act()
@@ -314,7 +330,8 @@ await That(Act).Throws<MockVerificationException>()
 		public async Task VerifyPropertyTyped_Setter_FailureMessageIncludesSetPropertyPrefix()
 		{
 			FastMockInteractions store = new(1);
-			store.InstallPropertySetter<int>(0);
+			store.GetOrCreateBuffer<FastPropertySetterBuffer<int>>(0,
+				static f => new FastPropertySetterBuffer<int>(f));
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			void Act()
@@ -338,7 +355,8 @@ public async Task VerifyMethodTyped_WithMemberIdEqualToBufferLength_ShouldFallTo
 			// IndexOutOfRangeException-crash on `buffers[memberId]`. Asserting the verify
 			// resolves cleanly via the slow-path fallback documents the boundary.
 			FastMockInteractions store = new(1);
-			store.InstallMethod(0);
+			store.GetOrCreateBuffer<FastMethod0Buffer>(0,
+				static f => new FastMethod0Buffer(f));
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			void Act()
@@ -353,7 +371,8 @@ void Act()
 		public async Task VerifyMethodTyped_WithMemberIdFarOutOfRange_ShouldFallToSlowPath()
 		{
 			FastMockInteractions store = new(1);
-			store.InstallMethod(0);
+			store.GetOrCreateBuffer<FastMethod0Buffer>(0,
+				static f => new FastMethod0Buffer(f));
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			void Act()
@@ -488,7 +507,8 @@ public async Task Getter_FailureMessageIncludesGotPropertyPrefix()
 			// Pins the expectation factory `() => $"got property {propertyName...}"` against the
 			// string-removal mutation that would replace it with an empty interpolation.
 			FastMockInteractions store = new(1);
-			store.InstallPropertyGetter(0);
+			store.GetOrCreateBuffer<FastPropertyGetterBuffer>(0,
+				static f => new FastPropertyGetterBuffer(f, new PropertyGetterAccess(string.Empty)));
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			void Act()
@@ -507,8 +527,9 @@ public async Task Getter_WithBufferAndRecord_PredicateMatchesEveryRecord()
 			// Mutating it to `static _ => false` would skip every record and turn this Once() into a
 			// failed verification.
 			FastMockInteractions store = new(1);
-			FastPropertyGetterBuffer buffer = store.InstallPropertyGetter(0);
-			buffer.Append("X");
+			FastPropertyGetterBuffer buffer = store.GetOrCreateBuffer<FastPropertyGetterBuffer>(0,
+				static f => new FastPropertyGetterBuffer(f, new PropertyGetterAccess("X")));
+			buffer.Append();
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			void Act()
@@ -525,7 +546,8 @@ public async Task Setter_FailureMessageIncludesSetPropertyPrefix()
 			// Pins the expectation factory `() => $"set property {propertyName...} to {value}"`
 			// against the string-removal mutation.
 			FastMockInteractions store = new(1);
-			store.InstallPropertySetter<int>(0);
+			store.GetOrCreateBuffer<FastPropertySetterBuffer<int>>(0,
+				static f => new FastPropertySetterBuffer<int>(f));
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			void Act()
@@ -545,7 +567,8 @@ public async Task Setter_WithBufferAndMatchingRecord_PredicateMatchesByValue()
 			// Block-removal would turn the predicate into `return default;` (i.e. always false) and
 			// drop every recorded setter, failing this Once().
 			FastMockInteractions store = new(1);
-			FastPropertySetterBuffer<int> buffer = store.InstallPropertySetter<int>(0);
+			FastPropertySetterBuffer<int> buffer = store.GetOrCreateBuffer<FastPropertySetterBuffer<int>>(0,
+				static f => new FastPropertySetterBuffer<int>(f));
 			buffer.Append("X", 7);
 			MockRegistry registry = new(MockBehavior.Default, store);
 
@@ -564,7 +587,8 @@ public async Task Setter_WithNonMatchingValue_PredicateRejects()
 			// Same Predicate body — but exercises the negative branch so the `value.Matches(...)`
 			// term cannot be silently dropped.
 			FastMockInteractions store = new(1);
-			FastPropertySetterBuffer<int> buffer = store.InstallPropertySetter<int>(0);
+			FastPropertySetterBuffer<int> buffer = store.GetOrCreateBuffer<FastPropertySetterBuffer<int>>(0,
+				static f => new FastPropertySetterBuffer<int>(f));
 			buffer.Append("X", 99);
 			MockRegistry registry = new(MockBehavior.Default, store);
 
@@ -586,7 +610,8 @@ public async Task Got_FailureMessageIncludesGotIndexerPrefix()
 			// Pins `() => $"got indexer {parametersDescription()}"` in the public memberId-keyed
 			// IndexerGot expression body against the string-removal mutation.
 			FastMockInteractions store = new(1);
-			store.InstallIndexerGetter<int>(0);
+			store.GetOrCreateBuffer<FastIndexerGetterBuffer<int>>(0,
+				static f => new FastIndexerGetterBuffer<int>(f));
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			void Act()
@@ -606,7 +631,8 @@ public async Task Set_FailureMessageIncludesSetIndexerPrefix()
 			// Pins `() => $"set indexer {parametersDescription()} to {value}"` against the
 			// string-removal mutation.
 			FastMockInteractions store = new(1);
-			store.InstallIndexerSetter<int, string>(0);
+			store.GetOrCreateBuffer<FastIndexerSetterBuffer<int, string>>(0,
+				static f => new FastIndexerSetterBuffer<int, string>(f));
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			void Act()
@@ -627,7 +653,8 @@ public async Task Set_WithBufferAndMatchingRecord_PredicateMatchesByValue()
 			// Pins the local Predicate body in the memberId-keyed IndexerSet overload — the
 			// block-removal mutant would turn it into `return default;` and skip every record.
 			FastMockInteractions store = new(1);
-			FastIndexerSetterBuffer<int, string> buffer = store.InstallIndexerSetter<int, string>(0);
+			FastIndexerSetterBuffer<int, string> buffer = store.GetOrCreateBuffer<FastIndexerSetterBuffer<int, string>>(0,
+				static f => new FastIndexerSetterBuffer<int, string>(f));
 			buffer.Append(1, "x");
 			MockRegistry registry = new(MockBehavior.Default, store);
 
@@ -651,7 +678,8 @@ public async Task FailureMessageIncludesSubscribedToEventPrefix()
 		{
 			// Pins the expectation factory `() => $"subscribed to event {eventName...}"`.
 			FastMockInteractions store = new(1);
-			store.InstallEventSubscribe(0);
+			store.GetOrCreateBuffer<FastEventBuffer>(0,
+				static f => new FastEventBuffer(f, FastEventBufferKind.Subscribe));
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			void Act()
@@ -669,7 +697,8 @@ public async Task WithBufferAndRecord_PredicateMatchesEveryRecord()
 			// Pins `static _ => true` in the memberId-keyed SubscribedTo. Mutating to `false`
 			// would drop every record and fail Once().
 			FastMockInteractions store = new(1);
-			FastEventBuffer buffer = store.InstallEventSubscribe(0);
+			FastEventBuffer buffer = store.GetOrCreateBuffer<FastEventBuffer>(0,
+				static f => new FastEventBuffer(f, FastEventBufferKind.Subscribe));
 			buffer.Append("Tick", null, typeof(object).GetMethod(nameof(ToString))!);
 			MockRegistry registry = new(MockBehavior.Default, store);
 
@@ -712,7 +741,8 @@ public sealed class UnsubscribedFromFastPathTests
 		public async Task FailureMessageIncludesUnsubscribedFromEventPrefix()
 		{
 			FastMockInteractions store = new(1);
-			store.InstallEventUnsubscribe(0);
+			store.GetOrCreateBuffer<FastEventBuffer>(0,
+				static f => new FastEventBuffer(f, FastEventBufferKind.Unsubscribe));
 			MockRegistry registry = new(MockBehavior.Default, store);
 
 			void Act()
@@ -728,7 +758,8 @@ await That(Act).Throws<MockVerificationException>()
 		public async Task WithBufferAndRecord_PredicateMatchesEveryRecord()
 		{
 			FastMockInteractions store = new(1);
-			FastEventBuffer buffer = store.InstallEventUnsubscribe(0);
+			FastEventBuffer buffer = store.GetOrCreateBuffer<FastEventBuffer>(0,
+				static f => new FastEventBuffer(f, FastEventBufferKind.Unsubscribe));
 			buffer.Append("Tick", null, typeof(object).GetMethod(nameof(ToString))!);
 			MockRegistry registry = new(MockBehavior.Default, store);
 
diff --git a/Tests/Mockolate.Tests/Verify/VerificationResultMutationTests.cs b/Tests/Mockolate.Tests/Verify/VerificationResultMutationTests.cs
index 4502daac..39824856 100644
--- a/Tests/Mockolate.Tests/Verify/VerificationResultMutationTests.cs
+++ b/Tests/Mockolate.Tests/Verify/VerificationResultMutationTests.cs
@@ -65,7 +65,8 @@ public async Task AwaitableVerifyCount_NoFastCountSource_AfterSuccess_MarksMatch
 		// IndexerGot(memberId, ...) returns a VerificationResult with a buffer but no fast-count
 		// source, so wrapping it with .Within(...) walks exactly that branch.
 		FastMockInteractions store = new(1);
-		FastIndexerGetterBuffer<int> buffer = store.InstallIndexerGetter<int>(0);
+		FastIndexerGetterBuffer<int> buffer = store.GetOrCreateBuffer<FastIndexerGetterBuffer<int>>(0,
+			static f => new FastIndexerGetterBuffer<int>(f));
 		buffer.Append(1);
 		MockRegistry registry = new(MockBehavior.Default, store);
 
@@ -95,7 +96,7 @@ public async Task CollectMatching_WithMultipleRecordsOutOfSeqOrder_SortsBySeqBef
 			(1L, rec1),
 			(3L, rec3),
 		]);
-		store.InstallBuffer(0, buffer);
+		store.Buffers[0] = buffer;
 		MockRegistry registry = new(MockBehavior.Default, store);
 
 		VerificationResult<object>.IgnoreParameters result =
@@ -123,7 +124,8 @@ public async Task SyncVerifyCount_NoFastCountSource_AfterSuccess_MarksMatchingIn
 		// Pins the `_interactions.Verified(matchingInteractions);` call inside the non-Awaitable
 		// IFastVerifyCountResult.VerifyCount second branch (when `_fastCountSource is null`).
 		FastMockInteractions store = new(1);
-		FastIndexerGetterBuffer<int> buffer = store.InstallIndexerGetter<int>(0);
+		FastIndexerGetterBuffer<int> buffer = store.GetOrCreateBuffer<FastIndexerGetterBuffer<int>>(0,
+			static f => new FastIndexerGetterBuffer<int>(f));
 		buffer.Append(1);
 		MockRegistry registry = new(MockBehavior.Default, store);