Simplify format-id schema for better code generation

.changeset/simplify-format-id-schema.md

@@ -0,0 +1,31 @@
+---
+"adcontextprotocol": patch
+---
+
+Simplify format-id schema structure for better code generation compatibility.
+
+**Problem**: The previous schema used a complex `oneOf`/`not`/`anyOf` pattern in `allOf` to express that width/height fields are optional but must appear together. This caused code generators to interpret the schema as two separate types (FormatId1, FormatId2) rather than a single type with optional fields, forcing union types everywhere format_id was used.
+
+**Solution**: Replaced the complex validation pattern with a simpler approach:
+- Moved width/height fields directly into the format-id schema properties
+- Used JSON Schema `dependencies` keyword to enforce that width and height must appear together
+- Maintained identical validation semantics while producing cleaner generated types
+
+**Impact**:
+- Code generators now produce a single FormatId type with optional width/height fields
+- No breaking changes to the wire format or validation behavior
+- Improved developer experience with better TypeScript/Python type hints
+- Eliminates need for union types when referencing format_id
+
+**Example generated type (TypeScript)**:
+```typescript
+// Before: FormatId1 | FormatId2
+// After:
+interface FormatId {
+  agent_url: string;
+  id: string;
+  width?: number;      // optional, but must have height if present
+  height?: number;     // optional, but must have width if present
+  duration_ms?: number;
+}
+```

static/schemas/source/core/format-id.json

@@ -15,6 +15,16 @@
       "pattern": "^[a-zA-Z0-9_-]+$",
       "description": "Format identifier within the agent's namespace (e.g., 'display_static', 'video_hosted', 'audio_standard'). When used alone, references a template format. When combined with dimension/duration fields, creates a parameterized format ID for a specific variant."
     },
+    "width": {
+      "type": "integer",
+      "minimum": 1,
+      "description": "Width in pixels for visual formats. When specified, height must also be specified. Both fields together create a parameterized format ID for dimension-specific variants."
+    },
+    "height": {
+      "type": "integer",
+      "minimum": 1,
+      "description": "Height in pixels for visual formats. When specified, width must also be specified. Both fields together create a parameterized format ID for dimension-specific variants."
+    },
     "duration_ms": {
       "type": "number",
       "minimum": 1,
@@ -23,23 +33,8 @@
   },
   "required": ["agent_url", "id"],
   "additionalProperties": false,
-  "allOf": [
-    {
-      "oneOf": [
-        {
-          "not": {
-            "anyOf": [
-              {"required": ["width"]},
-              {"required": ["height"]}
-            ]
-          }
-        },
-        {
-          "allOf": [
-            {"$ref": "/schemas/core/dimensions.json"}
-          ]
-        }
-      ]
-    }
-  ]
+  "dependencies": {
+    "width": ["height"],
+    "height": ["width"]
+  }
 }