@@ -0,0 +1,13 @@
+---
+'@objectstack/metadata-core': patch
+---
+
+Clause-②: no
+
+The `source` describe on `MetadataEventSchema` no longer lists `"fs"`, `"studio"`, `"rest"`, `"ai"` and
+`"git-import"` as origin labels: of those, only `fs` is written by any producer (`FileSystemRepository`),
+and no write path stamps an authoring surface there. It now says what the field is: the write path that
+produced the event, an open label its writer stamps rather than an enum to pick from or match against, for
+example `protocol.saveMetaItem`, `protocol.publishMetaItem`, `migrate-stored`, `sys-metadata-repo`
+(`SysMetadataRepository`'s default) or `fs`. The field stays `z.string()`, so no key, type, export or
+accepted value changes, and every repository emits exactly what it emitted before.
@@ -32,8 +32,10 @@ import { ObjectSchema, Field } from '@objectstack/spec/data';
  *  • `metadata` / `checksum` are nullable — DELETE rows have no body or
  *    hash. Readers must tolerate null on both columns.
  *
- *  • `source` records the producer ('sys-metadata-repo', 'fs',
- *    'studio', …) and feeds MetadataEvent.source on history() reads.
+ *  • `source` records the write path that produced the row — an open
+ *    label its writer stamps, not an enum of authoring surfaces
+ *    ('protocol.saveMetaItem', 'migrate-stored', 'sys-metadata-repo', …)
+ *    — and feeds MetadataEvent.source on history() reads.
  *
  *  Indexes are purpose-built for the two dominant read patterns:
  *    1. per-item history view      → `(type, name, version)`
@@ -133,9 +135,18 @@ export const SysMetadataHistoryObject = ObjectSchema.create({
     }),
 
     /**
-     * Producer of the event ('sys-metadata-repo', 'fs', 'studio',
-     * 'api', …). Defaults to 'sys-metadata-repo' on the canonical
-     * write path; preserved on history() reads as MetadataEvent.source.
+     * The write path that produced the event (= MetadataEvent.source): an
+     * open label its writer stamps, not an enum of authoring surfaces.
+     * `SysMetadataRepository` stamps the caller's label or its own default
+     * — 'sys-metadata-repo' (put / delete), 'sys-metadata-repo.publish'
+     * (promoteDraft), 'sys-metadata-repo.revert' (restoreVersion). The
+     * protocol names its method ('protocol.saveMetaItem',
+     * 'protocol.publishMetaItem', 'protocol.deleteMetaItem',
+     * 'protocol.rollbackMetaItem', 'protocol.revertCommit'); a stored-row
+     * rewrite passes 'migrate-stored'; `@objectstack/metadata`'s
+     * DatabaseLoader writes 'database-loader'. history() reads pass the
+     * stored value through and answer 'sys-metadata-repo' for a row that
+     * stored none.
      */
     source: Field.text({
       label: 'Source',
 
@@ -145,7 +145,12 @@ export const MetadataEventSchema = z.object({
   actor: z.string().nullable(),
   message: z.string().optional(),
   ts: z.string(),
-  source: z.string().describe('Origin label: "fs", "studio", "rest", "ai", "git-import", …'),
+  source: z.string().describe(
+    'Which write path produced the event: an open label its writer stamps, not an enum of '
+    + 'authoring surfaces to pick from or match against (e.g. `protocol.saveMetaItem`, '
+    + '`protocol.publishMetaItem`, `migrate-stored`, `sys-metadata-repo` as '
+    + '`SysMetadataRepository`\'s default, or `fs` from `FileSystemRepository`).',
+  ),
 });
 
 export type MetadataEvent = z.infer<typeof MetadataEventSchema>;