docs(multiuser): plan status, CLAUDE.md, security-architecture, README + changeset

Stamp the plan doc with shipped-by-phase status; add the multi-user Key Patterns
entry + State Files + case-spaces note to CLAUDE.md; add a multi-user section to
the security architecture (threat model: workspace separation, not a security
boundary) and a README opt-in section; add a minor changeset.

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

CLAUDE.md

@@ -196,6 +196,8 @@ Codeman is a Claude Code session manager with web interface and autonomous Ralph
 
 **Cross-session search** (COD-113/#133): `GET /api/search?q=&types=&limit=` federates an **in-memory** search across all live sessions — session metadata (name/workingDir/id), run-summary events, and per-session attachment-history file entries (workspace-relative path only; the server-private `externalPath` is never read). Pure core `searchSources()` in `search-service.ts` (substring-matches with hard per-type caps — no regex, so no ReDoS; no filesystem reads, so no traversal); `harvestSources()` in `search-routes.ts` gathers the in-memory sources. `SearchQuerySchema` bounds `q` (1–200), allowlists `types` (`session,event,file`), clamps `limit` (1–60). Returns the `{success,data}` envelope. Frontend: history-panel search box in `terminal-ui.js`. Types: `src/types/search.ts`.
 
+**Multi-user mode** (opt-in `--multiuser` / `CODEMAN_MULTIUSER=1`, OFF by default; branch `feat/multiuser-mode`, design `docs/multi-user-plan.md`): named users with individually scrypt-hashed passwords in `~/.codeman/users.json` (via `src/user-store.ts`: atomic 0600 write, short-TTL cache, SERIALIZED read-modify-write so a fire-and-forget `touchLastLogin` can't clobber a concurrent route write, last-admin invariants). Gated everywhere by `isMultiUserMode()` (`src/config/multiuser.ts`); when OFF, behavior is byte-identical to single-user (all scoping helpers short-circuit). ⚠️ **Not a security boundary at the agent layer** — every session still runs as the SAME OS account; this separates WORKSPACES, it does not sandbox users (Docker cases are the isolation story). Auth: a PARALLEL async branch in `middleware/auth.ts` (single-user branch untouched) verifies `username:password` against the store, mints identity-carrying cookies (`AuthSessionRecord` gains `username`/`role`/`mustChangePassword`), decorates `req.authUser` (Fastify augmentation; single-user leaves it undefined and the ownership helpers default to a synthetic admin), enforces a per-username failure bucket + the `mustChangePassword` lockbox. Ownership threads through `Session.owner` (stamped from `req.authUser`/`job.owner` at every `new Session()`, round-tripped via `MuxSession.owner` on recovery); `findSessionOrFail(ctx,id,req)` does a NOT_FOUND owner check; list endpoints + `getLightState` + SSE (`deriveSseHint` routes session-scoped events by owner, fail-closed; machine-level + host-plan telemetry admin-only) + WS + search + file-preview all filter by owner. §6.3 permission policy: non-granted users are forced to `--permission-mode auto` (via `resolveClaudeModeForUser` at all spawn sites, incl. one-shots because `buildPromptArgs` now respects the session mode), and shell mode / cron `launchCommand` require the `canBypassPermissions` grant. Cases live in per-user `~/codeman-users/<name>/cases` (`resolveCasesDir`); a non-admin's `workingDir` is realpath-confined there; host CRUD is admin-only. Admin API `src/web/routes/admin-routes.ts` (`/api/admin/users*`, one-time passwords, audit log `admin-audit.jsonl`) + self-service `/api/me` + `/api/me/password` (`me-routes.ts`); frontend `public/admin-ui.js` (identity boot, change-password modal + interceptor, admin Users tab). CLI `codeman users add|passwd|list|rm`. Per-user session cap via `assertSessionCapacity`/`sessionCapacityMessage`. Tests: `test/user-store.test.ts`, `test/multiuser-auth.test.ts`, `test/ownership-scoping.test.ts`, `test/admin-routes.test.ts`, `test/admin-ui.test.ts`.
+
 **Away digest** (COD-41/#136): `GET /api/away-digest?range=&since=&until=&lastViewed=` aggregates "what happened while you were away" from the lifecycle log + run-summary events + live sessions + daily token stats + recently-completed subagents into needs-attention/completed/still-running/idle/informational sections. Pure aggregator in `web/away-digest.ts` (`resolveAwayDigestRange()` validates the window — `since-last-visit`/`1h`/`today`/`24h`/`custom`, server-local TZ; `buildAwayDigest()` classifies). Header-button modal in `panels-ui.js` (button hidden on phones — regression-guarded). ⚠️ Returns `{success:true,digest}` (a legacy raw-ish shape, consistent with the other raw GET handlers in `system-routes.ts` — `{entries}`/`{config}`/`{files}`/`getSystemStats()`); frontend + tests read `.digest`. Subagent lookback is a fixed 60-min window regardless of range.
 
 **Ralph todo-config** (COD-79/#135): per-session `maxTodos` (FIFO-eviction cap, default 500 = `MAX_TODOS_PER_SESSION`) + `todoExpirationMinutes` (auto-expiry, default 60) set via `POST /api/sessions/:id/ralph-config` (`RalphConfigSchema`, both `.int().positive()`). Stored on the tracker (`setMaxTodos`/`setTodoExpirationMinutes`) and **persisted/read-back via `RalphTrackerState`** (surfaced in the `loopState` getter → `toState()` + SSE broadcast → modal `populateRalphForm`), mirroring how `maxIterations` round-trips. Claude-only (skipped by `isExternalCliMode`).
@@ -267,7 +269,7 @@ Frontend JS modules have `@fileoverview` with `@dependency`/`@loadorder` tags. L
 
 ## State Files
 
-All in `~/.codeman/`: `state.json` (sessions, settings, respawn, orchestrator, `cronJobs`/`cronJobRuns`), `mux-sessions.json` (tmux recovery), `settings.json` (user prefs), `push-keys.json` (VAPID), `push-subscriptions.json`, `session-lifecycle.jsonl` (audit log), `update-status.json` (self-updater progress, polled across the service restart), `linked-cases.json` (linked-case registry used for case-path resolution), `remote-hosts.json` + `remote-cases.json` (remote SSH hosts/cases, COD-94), `docker-hosts.json` + `docker-cases.json` (docker hosts/cases, 1.4.0) + `docker-exports/` (portable container bundles), `subagent-window-states.json` + `subagent-parents.json` (subagent window layout, GET/PUT `/api/subagent-window-states`/`-parents`), `hook-secret` (per-instance hook secret, COD-54), `certs/` (self-signed TLS for `--https`), `.env` (CODEMAN_USERNAME/PASSWORD fallback for the `codeman attach` CLI). Transient: `self-update-runner.sh`.
+All in `~/.codeman/`: `state.json` (sessions, settings, respawn, orchestrator, `cronJobs`/`cronJobRuns`), `mux-sessions.json` (tmux recovery), `settings.json` (user prefs), `push-keys.json` (VAPID), `push-subscriptions.json`, `session-lifecycle.jsonl` (audit log), `update-status.json` (self-updater progress, polled across the service restart), `linked-cases.json` (linked-case registry used for case-path resolution), `remote-hosts.json` + `remote-cases.json` (remote SSH hosts/cases, COD-94), `docker-hosts.json` + `docker-cases.json` (docker hosts/cases, 1.4.0) + `docker-exports/` (portable container bundles), `subagent-window-states.json` + `subagent-parents.json` (subagent window layout, GET/PUT `/api/subagent-window-states`/`-parents`), `hook-secret` (per-instance hook secret, COD-54), `users.json` (multi-user accounts, scrypt hashes, mode 0600) + `admin-audit.jsonl` (multi-user admin action log), `certs/` (self-signed TLS for `--https`), `.env` (CODEMAN_USERNAME/PASSWORD fallback for the `codeman attach` CLI). Transient: `self-update-runner.sh`. Multi-user case spaces live OUTSIDE the data dir at `~/codeman-users/<username>/cases` (shared across instances like `~/codeman-cases`, override `CODEMAN_USER_SPACES_DIR`).
 
 **Generated top-level dirs** (all gitignored — don't edit or commit): `dist/` (esbuild output), `out/`, `coverage/`, `test-results/`, `tmp/`, `screenshots-echo-diag/`. The committed gesture bundle (`src/web/public/gesture/gesture-codeman.js`) IS tracked, but its runtime wasm/model assets (`src/web/public/gesture/wasm/`, `*.task`) are fetched and gitignored.