chore(workplan): add T07 schema migration guard for vocabulary_ref

References EP-CAP-003 (custodian capabilities domain) — ensures the
ApprovedAbility/ApprovedCapability name fields leave room for a future
nullable vocabulary_ref without a painful migration. Guard task only,
no schema changes needed now.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

workplans/RREG-WP-0002-production-hardening.md

@@ -24,7 +24,7 @@ are reviewable; approved registry truth is explicit.
 
 ```task
 id: RREG-WP-0002-T01
-status: todo
+status: in_progress
 priority: high
 state_hub_task_id: "a27142a6-c160-4453-ab59-50a7db92f9c4"
 ```
@@ -106,3 +106,33 @@ Versioned API path or explicit compatibility policy. Golden OpenAPI snapshot tes
 schema-diff check. More response examples for discovery and change-review endpoints.
 Error response schema for common 400/404 cases. Acceptance: breaking changes are
 deliberate and visible in tests; agent-facing endpoints have stable models.
+
+## Schema migration guard for vocabulary_ref (EP-CAP-003)
+
+```task
+id: RREG-WP-0002-T07
+status: todo
+priority: medium
+state_hub_task_id: "6f06d8bb-0ed9-47f1-8b3e-40f725e6ece6"
+```
+
+Audit the `ApprovedAbility` and `ApprovedCapability` (and `ApprovedFeature`) name
+fields to ensure no constraints would make adding a future nullable `vocabulary_ref`
+column a painful migration. Specifically verify:
+
+- No CHECK constraints that assume name is the sole identity of an ability/capability
+- No unique indexes on name alone (name + vocabulary_ref will be the future key)
+- No foreign keys from other tables pointing at name as a natural key
+- `ReviewDecision` records reference row IDs, not name strings
+
+This is a guard task, not an implementation task — no new columns needed now. The
+goal is to confirm the v0.1 schema leaves the door open. Document the finding in
+a short ADR note or inline comment.
+
+Context: EP-CAP-003 (Custodian State Hub, capabilities domain) — capability names
+are free-text in v0.1 but will eventually need anchoring to a named vocabulary
+version as terminology standardises from local ontology toward domain standard and
+commodity specification. EP-CAP-002 documents the related constraint that SBOM
+evidence can only corroborate or contradict capability claims, never generate them;
+the confidence scoring model will need named evidence factors when SBOM
+cross-referencing is added.