Record reference provenance in manifests

docs/integrations/json-output.md

@@ -98,6 +98,30 @@ approved.
 
 Fields with empty values may be omitted by JSON encoding.
 
+`source_digests` contains source document digests only. Bound references are
+recorded separately under `references`, which contains provenance only:
+lane ID, slot name, origin type and URI, digest, media type, byte size, and
+binding source. Reference content is not written to durable output.
+
+When references are bound, the manifest section has this shape:
+
+```json
+{
+  "references": [
+    {
+      "lane_id": "events",
+      "slot_name": "roster",
+      "origin_type": "file",
+      "origin_uri": "file:///absolute/path/roster.txt",
+      "digest": "sha256:...",
+      "media_type": "text/plain; charset=utf-8",
+      "size_bytes": 123,
+      "binding_source": "config"
+    }
+  ]
+}
+```
+
 `module_metadata` is omitted when no singleton module provides metadata.
 
 `validation_status` is `approved` when no candidates were rejected and