Record top-level module metadata in run manifests

docs/integrations/json-output.md

@@ -58,6 +58,18 @@ approved.
   "pipeline_digest": "sha256:...",
   "input_module": "seriatim",
   "chunker": "generic",
+  "module_metadata": {
+    "chunker": {
+      "prompt_id": "dnd.scenes",
+      "prompt_version": "v1",
+      "prompt_sha256": "sha256:...",
+      "response_schema_key": "dnd_scenes",
+      "response_schema_id": "schema-dnd-scenes",
+      "response_schema_name": "dnd_scenes",
+      "response_schema_version": "v1",
+      "response_schema_sha256": "sha256:..."
+    }
+  },
   "source_digests": ["sha256:..."],
   "extractors": ["dnd/spells"],
   "merger": "appendorder",
@@ -89,6 +101,10 @@ Fields with empty values may be omitted by JSON encoding.
 `validation_status` is `approved` when no candidates were rejected and
 `rejected` when one or more candidates were rejected.
 
+Top-level `module_metadata` is reserved for singleton pipeline modules
+(`input`, `chunker`, and `output`). Lane-owned module metadata remains under
+`artifact_lanes[].metadata`.
+
 ## Artifact Files
 
 Each artifact file has this shape: