diff --git a/src/app/api/upload/route.ts b/src/app/api/upload/route.ts
index 410715ef5..ab1d0f1f0 100644
--- a/src/app/api/upload/route.ts
+++ b/src/app/api/upload/route.ts
@@ -91,6 +91,12 @@ export async function POST(request: Request) {
     supabase = createAdminClient();
     const adminSupabase = supabase;
     const access = await publicAccessContext(request, adminSupabase);
+    // Anonymous ("public") uploads are pooled under the non-null PUBLIC_WORKSPACE_OWNER_ID as a
+    // moderation quarantine: pooled documents are intentionally NOT anonymously viewable and NOT in
+    // RAG retrieval (both gated on owner_id IS NULL) until an operator reviews and promotes them via
+    // scripts/promote-public-documents.ts (or the promote migration). This is the documented
+    // public-workspace model — see TEN-N3 in docs/tenancy-defense-in-depth-review.md and
+    // withOwnerReadScope in src/lib/public-api-access.ts. Do not make pooled uploads public here.
     const uploadOwnerId = access.ownerId ?? (publicUploadsEnabled() ? publicWorkspaceOwnerId() : null);
     if (!uploadOwnerId) {
       return NextResponse.json({ error: "Public uploads are not configured for this workspace." }, { status: 503 });
diff --git a/src/lib/public-api-access.ts b/src/lib/public-api-access.ts
index 330f75e80..2d238cf77 100644
--- a/src/lib/public-api-access.ts
+++ b/src/lib/public-api-access.ts
@@ -59,7 +59,16 @@ type OwnerScopedQuery<T> = {
   or(filters: string): T;
 };
 
-/** Scope reads to public rows (owner_id IS NULL) and, when signed in, the caller's owned rows. */
+/**
+ * Scope reads to public rows (owner_id IS NULL) and, when signed in, the caller's owned rows.
+ *
+ * Anonymous callers intentionally see ONLY the public corpus (owner_id IS NULL). Documents pooled
+ * under PUBLIC_WORKSPACE_OWNER_ID by anonymous uploads (see upload/route.ts) are a deliberate
+ * moderation quarantine: they stay out of anonymous viewing here — and out of RAG retrieval, which
+ * is gated separately on owner_id IS NULL — until an operator reviews and promotes them to
+ * owner_id IS NULL via scripts/promote-public-documents.ts (or the 20260706120000 promote
+ * migration). Do not union the pool owner in here without making that content-moderation decision.
+ */
 export function withOwnerReadScope<T extends OwnerScopedQuery<T>>(query: T, ownerId: string | undefined): T {
   if (ownerId) return query.or(`owner_id.eq.${ownerId},owner_id.is.null`);
   return query.is("owner_id", null);