docs: open Phase 1 — architecture spec set over the Phase 0 evidence

docs/architecture/ now exists: README index, overview, five component
specs (core-contract, engine-sqlite, engine-postgres, queues,
deployment), ADR-001..007 carrying the Phase 0 resolved decisions
(crate split, feature scope, per-engine drivers, dependency
ownership, wake contract, tx seam), and the centralized
open-questions tracker promotion: OQ-ST-01..08 mirror to OQ-01..08
one-to-one with statuses/resolutions carried; new Phase 1 questions
append (OQ-09 scheduler collapse, OQ-10 contract versioning).
Open Phase 1 work: OQ-04 contract pinning (high), OQ-05 queue
semantics depth (high), OQ-06 honker-core quality read (high;
fork-trigger gate), OQ-08 capability surface, OQ-09, OQ-10.

Erratum fixed in phase-0 OQ-ST-04 (thread-affinity friction is
SQLite-side, previously garbled as pg-side) and a stale scheduler-
boundary pointer corrected in consumer-inventory.md. Two review
passes run (findings: OQ-promotion numbering faithfulness, ADR
back-reference sync) — all critical/warning findings resolved.

docs/research/phase-0.md

@@ -1,10 +1,11 @@
 ---
 status: draft
-last_updated: 2026-10-04 (Phase 0 research complete. Both POCs ran, passed,
-and are folded into the register; the register itself was restructured
-after the findings review for consistency. OQ-ST-01/02/03/07 resolved;
-OQ-ST-04/05/06 de-risked with only contract/design work remaining;
-OQ-ST-08 open. Convergence recorded in §Convergence. Next: Phase 1.)
+last_updated: 2026-10-04 (Phase 0 complete and the register promoted:
+docs/architecture/ opened with ADR-001..007 carrying the resolved
+decisions and the OQ tracker mirroring OQ-ST-01..08 1:1. Phase 0
+research itself is closed; remaining work is in docs/architecture/
+open-questions.md. One erratum fixed in OQ-ST-04's tx-friction line —
+thread-affinity is SQLite-side, previously garbled as "pg-side".)
 ---
 
 # alkstore — Phase 0 (Exploration)
@@ -370,7 +371,10 @@ convention in the contract.
 ## Open Questions
 
 Register in `docs/research/phase-0.md`; IDs OQ-ST-NN (stable, append
-only). Promotion target: Phase 1 `docs/architecture/open-questions.md`.
+only). Promotion target: Phase 1 `docs/architecture/open-questions.md`
+— **promoted 2026-10-04**: OQ-ST-01..08 mirror 1:1 to OQ-01..08 there
+(their statuses and resolutions carried; resolved decisions carried
+into ADRs 001–007), and new Phase 1 questions append from OQ-09.
 Status conventions: `resolved` (evidence recorded here); `open —
 <work-type>` where the work-type names the remaining work and the
 entry is de-risked (the remainder is Phase 1 architecture work, not
@@ -591,11 +595,14 @@ Evidence now in hand (both POCs, 2026-10-04):
   caller-held tx handle (`*_tx` methods on the handle); pg's instance
   is async-native (tokio-postgres Client is Send+Sync — the handle
   holds the pooled connection directly, no spawn_blocking), SQLite's
-  is a bridged writer-slot lease. The core-crate `TxHandle` trait
-  from POC #1's sketch stands unchanged; the per-engine difference is
-  bridging mechanism, not trait shape. Phase 1 starts from that shape
-  plus its two recorded frictions (the `as_any_mut` downcast and the
-  thread-affinity of rusqlite tx ops — the latter pg-side only).
+   is a bridged writer-slot lease. The core-crate `TxHandle` trait
+   from POC #1's sketch stands unchanged; the per-engine difference is
+   bridging mechanism, not trait shape. Phase 1 starts from that shape
+   plus its two recorded frictions (the `as_any_mut` downcast and the
+   thread-affinity of rusqlite tx ops — the latter SQLite-side only;
+   erratum 2026-10-04, this line previously said "pg-side only," which
+   garbled POC #2's finding that the affinity friction does not carry
+   over to pg).
 
 ### OQ-ST-05: Queue semantics — adopt, fork, or re-derive?
 
@@ -743,8 +750,10 @@ The expected sequence, with what actually happened:
    with the POCs; per-subsystem votes recorded at the OQs. Remaining:
    the semantics-depth design inputs (OQ-ST-05) and the Phase-1
    quality read (OQ-ST-06's fork trigger).
-5. **Converge** — done (§Convergence). Phase 1 opens with the ADR
-   backlog this register becomes.
+5. **Converge** — done (§Convergence). Phase 1 opened 2026-10-04:
+    `docs/architecture/` now exists (README index, seven ADRs
+    001–007 carrying this register's resolved decisions, spec docs,
+    and the promoted open-questions tracker).
 
 ## References