ADR-014: transactional outbox enqueue — outbox_enqueue_tx on TxHandle (OQ-13 resolved)

docs/architecture/engine-sqlite.md

@@ -125,6 +125,7 @@ family is `__alkstore_*` (ADR-010 §8's naming authorization).
 | [011](decisions/011-sqlite-substrate-fork.md) | Substrate fork | OQ-06's trigger fired; substrate owned, queue ops re-derived on contract v1 |
 | [012](decisions/012-forked-substrate-design.md) | Fork design | contract-blind substrate, fidelity posture, port deltas, panic-free watcher death |
 | [013](decisions/013-fold-substrate-into-sqlite.md) | Substrate packaging | folded into `alkstore-sqlite` (`src/substrate/`); no fourth crate |
+| [014](decisions/014-outbox-tx-enqueue.md) | Outbox tx enqueue | `outbox_enqueue_tx` on `TxHandle`; derivation engine-side through the writer-slot lease |
 
 ## Open Questions
 
@@ -137,8 +138,12 @@ questions affecting this document:
   [ADR-011](decisions/011-sqlite-substrate-fork.md); trigger fired).
 - **OQ-12**: streams depth (affects this engine's stream realization
   — key column, event shape, retention) ([open](open-questions.md))
-- **OQ-13**: transactional outbox enqueue shape (affects this
-  engine's `TxHandle` impl) ([open](open-questions.md))
+- **OQ-13**: transactional outbox enqueue shape — **resolved**
+  (2026-10-05, [ADR-014](decisions/014-outbox-tx-enqueue.md)):
+  `outbox_enqueue_tx(outbox, opts, payload)` on the `TxHandle` trait;
+  the SQLite handle routes the op through the writer-slot lease
+  ([ADR-007](decisions/007-transactional-seam.md)) into the forked
+  substrate's `__alkstore_outbox:{name}` backing queue.
 
 Resolved: **OQ-09** (scheduler collapse —
 [ADR-009](decisions/009-scheduler-collapse.md)) and **OQ-05** (queue