docs(reviews): post-remediation re-review — gate passed, specs to reviewed

- docs/reviews/002-post-remediation-review.md: verifies all 14 review-001
  findings landed faithfully (sibling-source re-verification + gix-transport
  async_trait(?Send) check + four-config/MSRV probes), records the eight
  residual findings (R-1..R-8) and their resolutions (ADR-018 + doc batch)
- README lifecycle: draft→reviewed allows properly-tracked non-circular
  OQ deferrals (release-timing OQ-03 no longer blocks the transition) — R-7
- overview/transport/backend/doors/open-questions: frontmatter flipped to
  reviewed, timestamps refreshed; ADR-018 added to all ADR tables and the
  OQ-03 freeze-inventory narrative

Phase-1 gate verdict: decomposition may begin
Verification: cargo doc/test/clippy/fmt clean; four feature configs +
MSRV 1.88 check/clippy clean

docs/architecture/overview.md

@@ -1,6 +1,6 @@
 ---
-status: draft
-last_updated: 2026-09-25
+status: reviewed
+last_updated: 2026-09-30
 ---
 
 # Overview: alkgit
@@ -32,8 +32,8 @@ Single crate `alkgit`:
 | Producer | `GitAdapter` (`alk/git` ALPN via alkcall `ProtocolHandler`; parses the ADR-016 request-line preamble), channels `register_openable` (`channels/git/sub` — open-op params `{repo, service}`, the negotiation + service selector + ACL point; ADR-016) | POC-1 verbatim |
 | Consumer | `GitSession` typed client (`connect_direct`, `open_via_channels`) — ADR-017: `ls_refs`/`fetch`/`push`; fetch via gitoxide client machinery over a custom alkcall Transport, push hand-rolled to ADR-013's shapes; the replication/mirroring primitive for alknet | new, specified (grammar capture-grounded: ADR-013/014 + captures) |
 | Substrate | duplex session + stateless request/response layer (ADR-005); wire framing, V2 state machines (ADR-003) | POC-1, POC-3 |
-| Backends | `GitRegistry` (+ write supertrait), `GitRefs`, `GitPackGen`, `GitPackIngest` traits; impls behind the default-on `gix` (engine) and `registry-file` (records) features | POC-2 (gix impl) |
-| Management ops | `git/repo/*` call ops over `GitRegistryStore` (ADR-012 §3) — the JSON half alongside the `alk/git` open op (first dual-kind payload; ADR-012 §5) | thin over the store trait |
+| Backends | `GitRegistry` (+ write supertrait), `GitRefs`, `GitPackGen`, `GitPackIngest` traits (signatures pinned: ADR-018); impls behind the default-on `gix` (engine) and `registry-file` (records) features | POC-2 (gix impl) |
+| Management ops | `git/repo/*` call ops over `GitRegistryStore` (ADR-012 §3) — the JSON half alongside the `alk/git` open op (first dual-kind payload; ADR-012 §5); types/schemas pinned in backend.md §"Registry types and schemas" | thin over the store trait |
 
 Feature model: `gix` (engine impls) and `registry-file` (record store +
 ops) are independent default-on seams (ADR-012 §4);
@@ -95,6 +95,7 @@ multi-round negotiation are design-complete against real-client captures
 | [015](decisions/015-manage-grant-and-op-gate.md) | Manage grant + op gate | `manage` tier, admin-OR-manage gate, create seeds manage |
 | [016](decisions/016-native-session-preamble.md) | Native session preamble | `{repo, service}` open-op params, request-line preamble, service in the tuple |
 | [017](decisions/017-consumer-half-git-session.md) | Consumer half | `GitSession` typed client, custom alkcall Transport + gix-protocol fetch, hand-rolled push |
+| [018](decisions/018-backend-trait-signatures-and-storage-error-model.md) | Trait signatures + storage errors | object-storage trait signatures pinned, `StorageError` for traits 3–5, `&RepoRecord` repo param |
 
 ## Open Questions
 
@@ -105,7 +106,8 @@ Key questions tracked in [open-questions.md](open-questions.md):
   the ADR-015 three-action grant shape must land in it; the ADR-016
   native preamble wire shapes — `{repo, service}` params schema and the
   request-line grammar — entered it; ADR-017's `GitSession` public API
-  enters it).
+  enters it; ADR-018's trait signatures + shared types + `StorageError`
+  complete the backend-seam inventory).
 - **OQ-05**: sha256 policy (deferred(scope), low).
 - **OQ-16**: grant-key identity namespace (deferred(scope); blocks
   nothing in v1 — ADR-015 §7).