Track datasetRefs against the live draft so manual edits and extract link immediately

src/core/snippet.ts

@@ -40,7 +40,9 @@ export interface Snippet {
   comment: string;
   /** User-assigned labels. */
   tags: string[];
-  /** Names of datasets referenced by this spec (maintained on publish). */
+  /** Names of datasets referenced by the draft spec; mirrors the version being
+   *  edited, recomputed on every draft change (create/auto-save/extract/revert)
+   *  and on publish (docs/architecture/07 §3). */
   datasetRefs: string[];
   /** Free-form, extensible metadata bag. */
   meta: Record<string, unknown>;