Draft capability entry (reuse-surface REUSE-WP-0017-T04, cohort 3)

Honest first-pass maturity vector grounded in README/docs/tests present
in this repo; no invented evidence. Flagged for human review before
publish. See reuse-surface history/2026-07-06-coverage-classification.md.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

registry/indexes/capabilities.yaml

@@ -1,4 +1,19 @@
 version: 1
-updated: '2026-06-16'
+updated: '2026-07-06'
 domain: helix_forge
-capabilities: []
+capabilities:
+- id: capability.identity.user-engine
+  name: Headless Multi-Tenant User Engine
+  summary: Headless, multi-application, multi-tenant user management engine covering registration, identity/factor
+    models, entitlement claims, hats/realms/services/assets access profiles, and onboarding journeys.
+  vector: D4 / A1 / C2 / R0
+  domain: communication
+  status: draft
+  owner: user-engine
+  path: registry/capabilities/capability.identity.user-engine.md
+  tags:
+  - identity
+  - user-management
+  - multi-tenant
+  consumption_modes:
+  - library import