tools(relay): durable JSONL message log + pm wrapper + 120-char preview

- queue.ts: append every posted message to relay-log.jsonl (full body,
  survives the consume-once drain + restarts). gitignored.
- server.ts: bump the stdout preview from 60 to 120 chars.
- tools/relay/pm: absolute-path bash wrapper (read|pending|send) so relay
  ops work from any cwd without cd or hand-built JSON escaping.
- Fold in Dev-C's Phase 6 ARCHITECTURE.md slice as a coordination artifact.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/superpowers/coordination/v0.7-dev-c-architecture-slice.md

@@ -0,0 +1,68 @@
+# Dev-C ARCHITECTURE.md slice — Plan C Phase 6 (`get_vault_status` + sidebar status indicator)
+
+Ready-to-fold additions for `extension/ARCHITECTURE.md`, scoped to Dev-C's Phase 6 work only.
+Phase 3 (`create_vault`/`attach_vault`, setup-SW migration) and Phase 4 (the `vault.ts` →
+`vault-shell`/`vault-sidebar`/`vault-list`/`vault-drawer`/`vault-form-wrapper` split) doc updates
+are Dev-A's / Dev-B's slices — not included here.
+
+Merged to origin/main as `397cc78` (Merge Plan C Phase 6). Local source ref: `675452a`.
+
+---
+
+## 1. SW message-protocol row — `get_vault_status` (read-only, popup-only)
+
+**Where:** the `router/popup-only.ts` bullet in the service-worker module map (around line 270),
+and/or wherever the read-only popup messages are enumerated.
+
+**Add:**
+
+> - `get_vault_status` (popup-only, read-only) — returns the cached sync summary
+>   `{ ahead, behind, lastSyncAt, pendingItems }` with **no network call**. `ahead`/`behind`/
+>   `lastSyncAt` are read straight off `state.gitHost` (populated by the `sync` handler, which
+>   records `lastSyncAt = Math.floor(Date.now()/1000)` — unix **seconds** — after a successful
+>   manifest fetch). `pendingItems` is a live count of active (non-trashed) manifest entries via
+>   `vault.listItems(manifest).length`. `ahead`/`behind` are structurally always `0` in the
+>   extension (it writes straight to the host via the Contents REST API; there is no local commit
+>   graph) and exist for parity with `relicario status`. Handler: `vault.handleGetVaultStatus(state)`
+>   — synchronous; its `Pick<GitHost,'lastSyncAt'|'ahead'|'behind'>`-typed param both breaks the
+>   `PopupState` import cycle and structurally forbids it from making a network call.
+
+## 2. `git-host.ts` cache fields
+
+**Where:** the `git-host.ts` bullet in the SW module map (around line 299, listing the interface methods).
+
+**Amend** the interface description to note the cached sync metadata:
+
+> The `GitHost` interface also carries cached sync metadata —
+> `lastSyncAt: number | null` (unix seconds), `ahead: number`, `behind: number` — initialized to
+> `null`/`0`/`0` in both `GiteaHost` and `GitHubHost`. The cache rides the gitHost lifecycle: it is
+> created on unlock and cleared whenever `state.gitHost` is nulled — on session-timer expiry
+> (`index.ts`) **and** on the explicit `lock` message handler (`popup-only.ts`), which now nulls
+> `state.gitHost` symmetrically so a lock→unlock cycle can't surface a stale `lastSyncAt`.
+
+## 3. Sidebar status-indicator UI flow
+
+**Where:** the `src/vault/` module map (around line 184). Add a `vault-status.ts` entry and a note on
+the `vault-sidebar.ts` footer wiring. (If Dev-B's Phase 4 slice has already added the `vault-sidebar.ts`
+entry, fold the status note into it rather than duplicating.)
+
+**Add:**
+
+> - `vault-status.ts` — sidebar-footer sync indicator renderer. `renderStatusIndicator(el, status)`
+>   is pure DOM: it renders, by priority, `N pending` / `N ahead` / `N behind`, falling back to
+>   `in sync`, plus a `last sync <relativeTime>` / `never synced` line. Reuses `shared/glyphs.ts`
+>   (`GLYPH_PENDING`/`AHEAD`/`BEHIND`/`SYNCED`) and `shared/relative-time.ts`. `VaultStatus` is an
+>   alias of `GetVaultStatusResponse['data']`, so the renderer's input shape is single-sourced from
+>   the message contract and can't drift from the SW handler.
+> - **Status-indicator flow** (in the `vault-sidebar.ts` entry): the footer holds a
+>   `#vault-status-slot` plus a manual `↻` refresh button (`GLYPH_REFRESH`). `wireSidebar` calls
+>   `refreshStatus()` once on mount and again on the button's click — sending `get_vault_status` via
+>   `ctx.sendMessage` and rendering the result into the slot. There is **no timer polling**: the
+>   indicator only refreshes on mount + explicit button press, matching the spec's
+>   no-network-without-user-intent discipline (sync is user-initiated).
+
+## 4. Living-docs note
+
+This closes the last `relicario status` CLI/extension parity gap (called out in the extension
+restructure spec, `docs/superpowers/specs/2026-05-04-extension-restructure-design.md`). `STATUS.md`
+should move the extension-restructure line to shipped as part of the Task 7.1 pass.