feat(metadata): C4 metamodelVersion marker — TS reference + shared manifest tag

Adds a rolled-up Metamodel spec-version string to the registry manifest as the first
top-level key (`metamodelVersion: "0"` — pre-1.0/unstable; the 1.0 cut freezes it to
"1.0"). A version TAG on the existing expected-registry.json manifest, exposed via
METAMODEL_VERSION + emitted by buildRegistryManifest, gated byte-for-byte by
registry-conformance (all ports must emit the same string). Not per-provider, not
per-file. TS reference; C#/Java/Kotlin/Python fan-out follows against the shared fixture.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GF9xLEQZaPus5Y6opk398n

Author: claude

fixtures/registry-conformance/expected-registry.json

@@ -1,4 +1,5 @@
 {
+  "metamodelVersion": "0",
   "types": [
     {
       "type": "attr",

server/typescript/packages/metadata/src/index.ts

@@ -146,7 +146,7 @@ export type { EffectiveConstraints } from "./constraint-merge.js";
 export { validateConstraints } from "./constraint-validate.js";
 
 // Registry conformance manifest (SP-G) — the canonical logical-vocabulary serializer.
-export { buildRegistryManifest, emitRegistryManifest, classifyPerTypeAttr } from "./registry-manifest.js";
+export { buildRegistryManifest, emitRegistryManifest, classifyPerTypeAttr, METAMODEL_VERSION } from "./registry-manifest.js";
 export type { AttrClassification } from "./registry-manifest.js";
 export { ExclusionReason } from "./registry-manifest-exclusions.js";
 

server/typescript/packages/metadata/src/registry-manifest.ts

@@ -97,8 +97,20 @@ interface ManifestType {
   parents?: string[];
 }
 
+/**
+ * The Metamodel spec version — the shared, rolled-up name for the frozen core
+ * vocabulary (ADR-0035 §2 / docs/1.0-readiness.md C4). It is a version TAG on this
+ * manifest (the byte-exact bill of materials), NOT a per-provider or per-file marker:
+ * every port emits the same string, asserted by registry-conformance. Pre-1.0 the
+ * vocabulary is in development, so this is `"0"` (semver major-0 = unstable); the 1.0
+ * cut (readiness G1) freezes it to `"1.0"`.
+ */
+export const METAMODEL_VERSION = "0";
+
 /** The full canonical manifest. All collections are sorted for byte-stability. */
 interface RegistryManifest {
+  /** The Metamodel spec version (first key — a header). See {@link METAMODEL_VERSION}. */
+  metamodelVersion: string;
   types: ManifestType[];
   commonAttrs: ManifestAttr[];
   defaultSubTypes: Record<string, string>;
@@ -317,7 +329,7 @@ export function buildRegistryManifest(registry: TypeRegistry): RegistryManifest
     }
   }
 
-  return { types, commonAttrs, defaultSubTypes };
+  return { metamodelVersion: METAMODEL_VERSION, types, commonAttrs, defaultSubTypes };
 }
 
 /**
@@ -326,7 +338,8 @@ export function buildRegistryManifest(registry: TypeRegistry): RegistryManifest
  * Serialization contract — every port MUST match this exactly:
  *  - 2-space indentation (JSON.stringify(_, _, 2)).
  *  - Object keys in a fixed order (JSON.stringify preserves insertion order):
- *    the manifest is built with `types`, `commonAttrs`, `defaultSubTypes`.
+ *    the manifest is built with `metamodelVersion` (first — the spec-version
+ *    header), then `types`, `commonAttrs`, `defaultSubTypes`.
  *    - Each attr: `name`, `valueType`, `isArray`, `required`, then optional
  *      `allowedValues` (omitted unless the attr declares a non-empty closed set —
  *      decision 5), then `description`, then optional `rules`, `example`,