swarm stage 2: peer-to-peer channel — /peer endpoints + peer tool ...

Server side (navi/api/routes/peer.py, port 8099):
- GET /peer/hello — open discovery ping (name, uuid prefix, version)
- GET /peer/status — PSK; identity, uptime, machine facts, hive view
- POST /peer/ask — PSK; one-shot agent run under PEER_ASK_PROFILE
  (default server_admin) answers, one concurrent ask at a time
- loop guard: answering agent runs without the peer tool (deterministic
  recursion cut) + own-uuid asks refused with 409
- verify_swarm_key in navi/swarm.py accepts .swarm-key.previous
  (rotation window, constant-time)

Client side (navi/tools/peer.py):
- peer tool: list (hive book, stale cache fallback marked), status,
  ask by swarm name; asks go direct peer-to-peer, hive never on the
  message path
- audit events on both sides (peer.ask_sent/received/answered/failed)

peer tool added to server_admin, navi_code, developer profiles.

swarm stage 1: instance identity, PSK, hive registry, announce loop ...

- navi/identity.py: adjective-animal names + uuid in instance.json
  (generated at install, renameable by hand)
- navi/swarm.py: HiveAnnouncer - periodic POST /announce to the hive
  with non-blocking reachability tracking (transitional logs, /health
  export, hive_status context provider reports outages to the agent)
- hive/: standalone FastAPI address book (SQLite, port 8087, PSK via
  X-Swarm-Key with .swarm-key.previous rotation window, TTL online
  status, host from client IP, port from payload). Not installed or
  started by default - run manually on the main server.
- ports moved to 8099 (API) / 8098 (UI MCP)
- install.sh: PYTHONIOENCODING=utf-8 in the systemd unit, generates
  instance.json and .swarm-key on fresh installs

profiles: retire gate flags and retrain prompts for the plan tool ...

- drop planning_enabled / planning_mandatory / planning_phase2_enabled /
  observe_skips_plan_enabled / adaptive_replan_enabled from AgentProfile,
  the loader and admin serialization
- add `plan` to native tools of developer, navi_code, tool_developer,
  secretary, server_admin, modeler_3d — without the gate they would
  otherwise lose planning entirely
- system prompts: call plan for non-trivial multi-step work before
  execution; complex plans get presented for confirmation; stuck or goal
  changed -> plan with a reason

security: critical batch 1 — RCE/XSS/CORS/webhook hardening ...

Backend:
- auth/deps: fix refresh-lock clock race (cleanup now monotonic like the cache)
- core/registry: add missing structlog logger (NameError on fallback path)
- config: GNAUTH_WEBHOOK_SECRET, NAVI_ALLOWED_ORIGINS (+list property)
- webhooks: HMAC-SHA256 signature verification (503 unconfigured in auth mode,
  unsigned+warning in no-auth mode, 403 bad/stale signature, 400 bad JSON)
- main: CORS from NAVI_ALLOWED_ORIGINS in auth mode (fail-fast on empty),
  eval router behind require_admin, /debug only registered in no-auth mode
- auth routes: mobile-done sid validation (32 hex) + CSP header + safe JS
  escaping (reflected XSS); Secure cookie flag via helper (https base URL)
- websocket: anonymous WS rejected in auth mode (closes legacy-session RCE);
  socket registered only after access checks; stop_session auth gate
- messages: REST agent start now takes session lock + busy flag (409 on
  active run), contextvars reset in finally

Webclient:
- useMarkdown: DOMPurify.sanitize on all rendered markdown (stored XSS),
  image-URL scheme whitelist, delegated error listener (no inline onerror)
- html.html artifact viewer: sandbox without allow-same-origin (opaque origin)
- tests: DOMPurify runs under jsdom (happy-dom Node.prototype.nodeName getter
  breaks DOMPurify); useWebSocket tests get localStorage stub + ui-kit alias

Tests: pytest 1049 passed, 1 skipped; vitest 61 passed

terminal: REST list/close endpoints + async client helpers (Etap 2) ...

The /terminals modal and the status-bar count need a server source for the
session's persistent terminals (background dev servers, etc.) and a way to
force-close one. Add REST endpoints over the existing TerminalManager:

- GET /sessions/{id}/terminals → terminal_manager.list(session_id) →
  {session_id, terminals: [summary,...]}. Access-checked (navi.sessions.read_all).
- POST /sessions/{id}/terminals/{name}/close → terminal_manager.close(...)
  → {session_id, terminal_name, closed: bool}. Name is URL-encoded by the
  client (terminal names may contain spaces).
- clients/terminal/api.py (async): list_terminals(session_id),
  close_terminal(session_id, name) — for the TUI modal + status-bar seed.

Tests: list empty / list returns active / close routes to manager / 404 on
unknown session (fake TerminalManager injected into the container, mirroring the
kv_store injection pattern). Full suite: 972 passed, 1 skipped.

Plan: docs/terminal_tool_plan.md — Etap 2 of 5.

Автономность мелких моделей: OUTPUT DISCIPLINE, milestone-todo, перехват финала хода ...

Два последовательных захода над одной проблемой — мелкие модели (12–30B) в navi_code
теряют автономность на трудных шагах: «остановился поболтать» вместо действия и
слишком большое расстояние между пунктами плана.

Заход 1 (З1–З3):
- З1: OUTPUT DISCIPLINE в системном промпте navi_code — «act, don't announce»,
  без few-shot антипримеров. Контракт хода: ответ без tool_calls = конец хода, поэтому
  объявление намерения текстом убивает автономность; правила заставляют вызывать
  инструмент в том же ходе.
- З2: плоский todo + метка группы milestone + декомпозиция. _parse_plan_steps
  возвращает list[tuple[milestone, text]]; milestone — метка группировки (не сущность,
  без статуса), «done» вычисляется при рендеринге; подшаги = больше плоских шагов
  (без вложенности). TUI side-panel группирует по milestone (плоский фолбэк при пустом
  milestone). Plan depth: max 15→20 + правило декомпозиции.
- З3: adaptive re-plan «длинный шаг» — nudge «разбей шаг» при in_progress ≥ порога
  итераций без смены todo (порог 4, раньше общего anti-stall warning на 8).

Заход 2 (шаги 1–3, после cloud-теста 31b vs 12b):
Корневая структурная причина: весь спасательный механизм (anti-stall warning с явным
предложением reflect, adaptive re-plan) живёт только внутри tool-цикла — nudge
инжектируется в pre_turn *следующей* итерации, которой при «остановился поболтать»
нет (ход закрылся по return до post_turn). 31b застревала через «продолжаю
tool-итерации» → дожала до warning → спаслась; 12b — через «замолчала текстом» → мимо
всех nudge.

- Шаг 1: перехват финала хода. Если модель выдала bare-text, но в todo есть открытые
  шаги (pending/in_progress) и лимит не исчерпан — НЕ эмитить StreamEnd, а сохранить
  ассистентский текст в session.context, поставить системный nudge и continue
  (без StreamEnd, без workers — консистентно с multi-iteration tool-турами). Счётчик
  final_interceptions на AgentTurnContext, лимит final_intercept_limit (default 2),
  эскалация жёсткости (мягкий → «second stop»). has_open_steps в todo.py: пустой
  todo → False (защита casual-сообщений), failed/skipped терминальны. Профильные
  флаги final_intercept_enabled/limit в base.py + loader + admin.
- Шаг 2: жёсткий reflect-триггер в промпте — «~3 tool attempts on the same step
  without progress → call reflect IN THIS TURN (tool call, not reasoning aloud)».
- Шаг 3: открыть replan для застревания — «call replan when reflect showed the whole
  approach is dead (not one failed step, but the approach itself)».

Тесты: 874 passed, 1 skipped. Новые — has_open_steps (5), final intercept (5),
milestone-группировка, adaptive long-step nudge, парсер шагов с milestone-маркером.

cloud: navi_code model → gemma4:31b-cloud для тестирования догадки (31b признала
застревание, 12b — нет); .env cloud-host уже gitignored.

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

Isolate sub-agent todo + render live todo in TUI side panel ...

Phase 1 — sub-agent todo isolation (backend):
- Add current_todo_session_id ContextVar; subagent_runner scopes it to the
  sub-agent's ephemeral run id so its auto-populated plan and todo updates
  land in an isolated KV row instead of clobbering the parent session's todo
  (which the parent's goal-anchoring reads every iteration).
- todo._sid() and planning.set_tasks prefer current_todo_session_id; the
  parent run leaves it unset, so all existing todo consumers (anti-stall,
  goal anchor, get_progress_message) behave exactly as before.

Phase 2 — live todo in the TUI right column:
- TodoUpdated event + emit it from the agent loop after planning auto-populate
  and after each tool-execution turn.
- GET /sessions/{id}/todos reads the parent session's todo KV row (explicit
  user_id/session_id, optional injected kv).
- api.get_todos + TodoList/TodoPanel widgets: status-coloured markers
  (pending dim, in_progress accent+bold, done success, failed error, skipped
  dim), progress header, scrollable panel below the auto-height info block.
- Hybrid delivery: REST seeds the panel on attach/switch, todo_updated WS
  events update it live.

Sub-agent todos as nested sub-lists is deferred to a later phase.

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

agent: bounded autonomy — scope boundary + observe-vs-act ...

navi_code had unwanted "free flight": an observe request ("look at a
directory") triggered the full Phase 3 plan with milestones + auto-todo,
and goal_anchoring then drove the agent to finish those steps, climbing
into sibling projects and executing milestone docs it found.

Two toggleable, default-off profile flags (on for navi_code):

- scope_boundary_enabled: injects a standing system message keeping the
  agent within the literally requested scope; forbids acting on
  discovered TODO/roadmap/milestone docs (report only).
- observe_skips_plan_enabled: Phase 1 classifies MODE: observe|act; an
  observe request skips Phase 2/3 — no multi-step plan, no auto-todo, no
  "execute step by step" prompt. The agent just gathers info and answers.
  Independent of force_plan (observe on the first message still skips).

Free flight stays reproducible by flipping both flags off.

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

Fix MCP names and profile API format consistency ...

- Replace stale mcp__navi_web__* / mcp__navi_3d__* names with canonical
  mcp__navi-web__* / mcp__navi-3d__* across prompts and key_tools.
- Update /agents/profiles and /admin/profiles endpoints to expose
  tools.agent / tools.subagent instead of deprecated enabled_tools fields.
- Update docs/mechanics.md to reference the new tools structure.
- Archive stale docs/visual.html.

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

Navi Code: Phase 1 — terminal-first profile, default profile mechanism, env/persona, tests ...

- Add navi_code profile (terminal-first coding assistant)
- Add NAVI_DEFAULT_PROFILE_ID setting and POST /sessions default profile fallback
- Add persona_navi_code.txt and .env.navi_code.example
- Add docs/plan_navi_code.md phased plan
- Update tests to verify default-profile selection in no-auth mode

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

Fix review issues for NAVI_AUTH_ENABLED feature ...

- Return 503 from /auth/login and /auth/callback when NAVI_AUTH_ENABLED=false
- Return model_copy() of _ANONYMOUS_USER to prevent accidental mutation
- Clean up __import__(datetime) in auth DDL
- Reorder FakeChatSession definition before use in tests
- Remove dead monkeypatch code in no-auth integration fixture
- Add unit test for get_current_user_ws in no-auth mode
- Add integration tests rejecting OAuth endpoints in no-auth mode

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

Add NAVI_AUTH_ENABLED switch for optional auth ...

- Add navi_auth_enabled setting (default true) to navi/config.py and .env.example
- When disabled, treat every request as anonymous admin user (id='anonymous')
- Create/update fixed anonymous navi_users row on startup
- Bypass OAuth/cookie/API-token resolution in navi/auth/deps.py
- Update /auth/status to return {enabled, configured}
- Log security warning on startup when auth is disabled
- Update webclient: skip fetchMe/login screen, show Local mode footer,
  expose /admin link, warn in API keys panel
- Rebuild webclient production bundle
- Add unit and integration tests for no-auth mode
- Update docs: auth.md, config.md, api.md, api_tokens.md, sessions.md,
  websocket.md, mechanics.md, index.md

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

Remove offline_access from OAuth scopes ...

gnexus-auth does not support offline_access yet (SUPPORTED scopes are
only openid, email, profile, roles, permissions). Requesting it caused
invalid_scope error and login failures.

Keep refresh token support as-is — tokens are still issued and
refreshed, just bound to the SSO session lifetime.

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

Fix OAuth callback to handle missing code and error responses ...

FastAPI validated code/state as required query params before the
handler body ran, so any OAuth error response (e.g. invalid_scope
from offline_access, user denied consent) produced an opaque 422
"Field required" instead of a readable error message.

- Make code, state, error, error_description all optional with defaults
- Detect OAuth error responses and return a clear 400 with the error
- Guard state[:8] slicing when state may be None

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

Make shared files and published content publicly accessible ...

Remove auth requirements from:
- GET /sessions/{id}/files/{filename} — direct download links (session ID
  acts as unguessable capability token)
- GET /sessions/{id}/content — published inline content list

Both endpoints still verify session exists and protect against path
traversal. File upload and file listing remain auth-gated.

Update tests to match new signatures.

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

Fix frequent OAuth logouts: offline_access scope, transient error handling, fetchMe resilience ...

- Add 'offline_access' to OAuth scopes so gnexus-auth issues offline
  refresh tokens instead of SSO-session-bound ones.
- Distinguish TokenRefreshException (invalid/expired refresh token)
  from transient network errors during token refresh:
  * TokenRefreshException → logout (token genuinely dead)
  * Other exceptions → fallback to cached user or API token
- Improve refresh failure logging with exc_type and error message.
- Frontend fetchMe: swallow non-401 errors so transient 5xx/network
  failures don't flash the login screen.

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

Add persistent multi-session terminal tool with background support ...

- New TerminalManager module: named subprocess sessions per Navi session,
  background readers, event-sink streaming, idle auto-cleanup
- Refactor terminal tool to multi-action: run, open, close, list,
  status, send_input
- Add TerminalOutputDelta and TerminalClosed events for streaming
- Wire TerminalManager into AppContainer, orchestrator, and registry
- Persist session_metadata in Session model and pg_session_store
- Close all session terminals on session delete
- Webclient: handle terminal_output/terminal_closed WS events,
  display live terminal output in tool cards
- Update unit tests for new terminal actions

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Fix 19 issues found in full codebase review ...

Backend:
- Stop session auth bypass: require auth for owned sessions, reject anonymous with 401
- upload_file: stream chunks directly to disk instead of buffering in RAM
- MCP config: validate name against path traversal regex
- auth deps: cleanup stale refresh locks periodically
- auth routes: expire mobile auth states after 10 min to prevent unbounded growth
- compressor: meta-summarize existing summaries before compression; preserve assistant content when tool_calls present; rewrite hard_truncate to keep whole turns
- orchestrator: configurable WS replay buffer size; async cleanup/remove_websocket/clear_busy; fix run_recall ContextVar order to avoid deadlock on _build_agent failure; await cleanup in finally
- agent: persist image_msg in session.messages; remove archived messages from session after archive; remove duplicate StreamStopped yield on tool stop
- websocket: try/except around create_task with cleanup on failure; await remove_websocket

Frontend:
- App.vue: hashchange listener lifecycle in onMounted/onUnmounted
- MessageList.vue: passive scroll, flash timeout cleanup, archive scroll snapshot
- InputBar.vue: 300 ms debounce on draft save to localStorage
- SessionList.vue: remove :key from DynamicScroller to avoid remount jitter

Tests: 422 passed, 1 skipped

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Add archive message pagination, configurable WS replay buffer ...

Backend:
- Add archive_threshold to Session model and getSession response
- Add next_before_seq to archive endpoint for cursor pagination
- Make WS replay buffer size configurable via WS_REPLAY_BUFFER_SIZE

Webclient:
- Add getArchivedMessages API function
- Add archive pagination state and loadArchivedMessages to chat store
- MessageList: auto-load older messages on scroll-to-top with scroll
  position preservation and loading spinner

Docs: update config.md with new env vars

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Fix broken MCP admin endpoints after deps refactor ...

Replace stale `_mcp_manager` module-level import with `get_mcp_manager()`
calls in admin endpoints. The module-level variable was removed during the
AppContainer refactor, causing 500 errors on:
- POST /admin/mcp/{server}/reconnect
- GET /admin/mcp/status
- POST /admin/mcp/test

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Apply review fixes to API token auth system ...

Backend:
- navi/auth/deps.py: replace 3 DB round-trips with single JOIN query for
  token resolution; update last_used_at still separate (best-effort)
- navi/api/routes/api_tokens.py: replace asyncpg-specific "UPDATE 1"
  string check with RETURNING id fetchrow; increase token_prefix from
  8 to 12 chars for better visual identification; add security notes
- tests/unit/auth/test_api_tokens.py: update tests for JOIN query and
  RETURNING-based revoke

Frontend:
- webclient/src/components/settings/ShowTokenModal.vue: new modal that
  shows the plain token in a readonly field with copy button and
  explicit warning — replaces the transient toast notification
- webclient/src/components/settings/ApiKeysPanel.vue: use ShowTokenModal
- webclient/src/composables/useWebSocket.js: add security comment about
  localStorage XSS risk and query param log exposure

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Add API token auth system for headless/micro clients ...

Backend:
- navi/auth/_ddl.py: add api_tokens table with boot-time migration
- navi/auth/deps.py: _resolve_user now falls back to X-Api-Token header
  and ?api_token query param for WebSocket auth
- navi/auth/__init__.py: add ApiToken pydantic model
- navi/api/routes/api_tokens.py: CRUD endpoints (POST/GET/DELETE)
- navi/main.py: wire api_tokens router

Frontend:
- webclient/src/App.vue: add #settings hash routing
- webclient/src/components/settings/: SettingsView, ApiKeysPanel,
  CreateKeyModal with copy-to-clipboard flow
- webclient/src/api/index.js: token CRUD API functions
- webclient/src/stores/apiTokens.js: Pinia store
- webclient/src/components/sidebar/AppSidebar.vue: settings link
- webclient/src/composables/useWebSocket.js: append ?api_token= when
  localStorage token is present

Tests:
- tests/unit/auth/test_api_tokens.py: 10 unit tests covering token
  resolution (header + query param), revoke, missing/revoked tokens,
  orphan users, and CRUD endpoints

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Migrate MCP tool naming from mcp:server:tool to mcp__server__tool ...

The colon separator (mcp:server:tool) confuses many LLMs during
tool-calling because colons appear in schemas and URLs. Switch to
double-underscore separator (mcp__server__tool) for robust parsing.

Key changes:
- navi/mcp/tools.py: add build_mcp_name(), parse_mcp_name(), is_mcp_tool()
- navi/core/tool_executor.py: update _resolve_tool() with new helpers
  and legacy colon fallback for old sessions
- navi/core/tool_utils.py, subagent_runner.py: use build_mcp_name()
- navi/api/routes/{admin,agents}.py: prefix via build_mcp_name()
- navi/tools/{list_tools,reload_tools}.py: migrated
- All profile configs + system_prompt.txt: replace mcp: with mcp__
- manuals/{model_3d,lint_scad,render_3d,spawn_agent}.md: updated
- mcp_servers.d/gnexus-book.json: instructions updated
- docs/{api,profiles,tools,mechanics,visual.html}: updated
- tests: test_tool_executor.py and test_mcp.py aligned

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Replace global lazy singletons with explicit AppContainer + lifespan ...

- Create navi/core/container.py with AppContainer dataclass and create_container()
- Rewrite navi/api/deps.py: remove module-level singletons, add _container global
  fallback + set_container(), use _resolve_container() for all getters
- Replace @app.on_event with @asynccontextmanager lifespan in main.py
- Update routes to use Depends(get_scheduler) instead of calling get_scheduler()
- Fix FastAPI body parsing bug: remove dataclass parameters from Depends getters
  (FastAPI was treating AppContainer sub-dependencies as Body params, forcing
  embed=True on all endpoint body params and causing 422 errors)
- Update websocket.py to use _resolve_container() instead of get_registries()
- Update integration test fixtures to build AppContainer and call set_container()
- Remove obsolete tests/unit/test_startup.py (tests removed _on_startup)
- Fix test_scheduler_loop.py fixture (get_registries no longer exists)

All 387 tests pass (excluding websocket hang tests).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

fix(recall): stabilize scheduled callback system and improve UX ...

Backend fixes:
- stop_session now stops headless recall runs via _busy_sessions dict
- _fire_recall sets user ContextVars so tools work correctly
- MaxIterationsReached treated as success, not failure
- skip_next_recall uses GREATEST(trigger_at, now) for overdue recalls
- schedule_recall rejects past trigger times
- timezone offset double-adjustment fixed for aware datetimes
- _fire_recall registers _AgentRun for reconnect/replay support
- session_sync race with stream_start fixed

Frontend improvements:
- Recall banner moved to ChatHeader with live Cancel/Skip buttons
- Recall messages styled with is_recall flag and badge
- Real-time recall updates via WebSocket (recall_update events)
- Recall filter moved to sessions-header as toggle button
- Session list shows clock icon for sessions with pending recall
- Empty state messages for empty/filtered session lists
- Fixed missing api import in ChatHeader.vue

Tests:
- Updated scheduler_loop tests for _busy_sessions dict change

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Refactor: move tool helper modules into _internal subpackage ...

Moves non-tool infrastructure out of navi/tools/ root so that only
actual tool classes live there:

  base.py           → _internal/base.py
  loader.py         → _internal/loader.py
  middleware.py     → _internal/middleware.py
  logging_middleware.py → _internal/logging_middleware.py
  _time_parser.py   → _internal/time_parser.py

All imports updated across core/, api/, mcp/, tools/, and tests/.
No proxy files remain in navi/tools/ root.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Add self-recall (scheduled callback) system ...

Core features:
- schedule_recall tool: once/recurring/immediate callbacks
- manage_recall tool: cancel/skip/list scheduled recalls
- Natural-language time parser (ISO, relative, "tomorrow at 09:00")
- PostgreSQL-backed RecallScheduler with lazy pool init
- Background recall_scheduler_loop with asyncio.Semaphore(3)
- _busy_sessions guard prevents user messages during headless runs
- Agent.run() preserves thinking field for session history visibility
- API endpoints: GET/DELETE/POST for session recall, admin list
- Frontend: recall badge, filter, cancel/skip in sidebar and chat header
- Tests: parser, scheduler CRUD, tools, API, scheduler loop (53 tests)
- Manuals: schedule_recall.md and manage_recall.md

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

feat: admin API endpoints for individual MCP server CRUD ...

Add granular REST endpoints for managing single MCP servers:
- GET  /admin/mcp/config/{server_name}
- PUT  /admin/mcp/config/{server_name}
- DELETE /admin/mcp/config/{server_name}

Bulk endpoints remain for backward compatibility.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Add session search across messages with backend + frontend ...

Backend:
- GET /sessions now accepts `search` query param
- _session_summary computes match_indices and match_preview from messages
- pg_session_store: messages ILIKE added to search_list and count_all
- In-memory store: search_list also filters by message content

Frontend:
- AppSidebar: search toggle icon + debounced input, Ctrl+K shortcut
- SessionItem: highlight matching text, show match_preview from search
- SessionList: pass searchQuery to SessionItem
- SessionsStore: searchQuery/searchActive state, setSearch/clearSearch
- API layer: getSessions accepts search param
- MessageList: scroll to target message + brightness flash animation
- ChatStore: loadSession accepts targetMessageIndex, scrollToMessageIndex ref
- CSS: msg-flash keyframe animation in app.scss
- Tests updated for new getSessions signature

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Add session file directory listing endpoint and Files tab in ArtifactsPanel ...

Backend:
- New GET /sessions/{session_id}/files endpoint (recursive, max depth 10)
- Includes hidden files, returns {path, size, is_dir, modified_at}
- Path traversal protection via resolve() + relative_to(base)
- list_session_files() helper in session_files.py

Webclient:
- Third "Files" tab in ArtifactsPanel alongside Artifacts and Links
- Tree display with depth-based indentation
- File type icons by extension (image, video, code, etc.)
- Download and inline-open actions per file
- Fetch on session load/reload via chatStore.fetchFiles()

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>