Why

The Ink TUI drives tui_gateway's dispatcher over newline-delimited JSON-RPC on stdio. That same dispatcher is what any browser/iOS/Android client would want to talk to — the protocol is transport-agnostic, but the code wasn't. This PR makes it transport-agnostic in practice, mounts a WebSocket bridge on the existing FastAPI dashboard, and adds a /chat page to the dashboard that drives the full agent loop over the socket as a live proof.

Goal: one dispatcher, multiple frontends. Ink keeps working byte-identically; new clients speak the same dialect over WebSocket without duplicating a single handler.

Backend

tui_gateway/transport.py (new)
Minimal Transport protocol + contextvars.ContextVar binding + a module-level StdioTransport. The stdio stream is resolved through a callback so the ~100 existing tests that monkeypatch.setattr(server, "_real_stdout", ...) keep working without modification.

tui_gateway/server.py
write_json and dispatch are now transport-aware. Precedence for routing:

1. Event frames with a session id → the session's bound transport (so async emits land on the right client even from pool worker threads).
2. Otherwise the transport bound on the current contextvar (set by dispatch for the lifetime of a request, propagated to pool workers via contextvars.copy_context()).
3. Otherwise the module-level stdio transport — the legacy path. tui_gateway/entry.py is unchanged externally; Ink's stdio handshake behaves identically.

_sessions[sid]["transport"] is populated at every session-creation call site (session.create, _init_session covering session.resume and session.branch).

tui_gateway/ws.py (new)
WSTransport + handle_ws coroutine. write is safe from any thread — it detects when it's called from the loop thread that owns the socket and fire-and-forget-schedules instead of deadlocking, otherwise uses run_coroutine_threadsafe(...).result(). handle_ws awaits writes inline via write_async for the frames it controls.

hermes_cli/web_server.py
Mounts /api/ws on the existing FastAPI app with the same ephemeral session-token gate used for REST. Adds HERMES_DASHBOARD_DEV_TOKEN env override so the Vite dev server (different port than the FastAPI backend) can share the token with the backend — no separate token-dispensing endpoint.

Frontend

web/src/lib/gatewayClient.ts (new)
Browser WebSocket JSON-RPC client, mirrors ui-tui/src/gatewayClient.ts. State listeners, typed on(type, cb) subscriptions, request/response map with timeout, reconnect on close.

web/src/lib/slashExec.ts (new)
Slash command pipeline: try slash.exec, fall back to command.dispatch, resolve the exec/plugin/alias/skill/send directives. Mirrors ui-tui/src/app/createSlashHandler.ts.

web/src/pages/ChatPage.tsx (new)
The chat view. Handles message.start/delta/complete, tool.start/progress/complete, error, session.info. Composer with Enter-to-send / Shift+Enter for newline. Interrupt button while busy. Reset session button. Copyable session id. Resume from ?resume=<id>.

web/src/components/SlashPopover.tsx (new)
Autocomplete popover above the composer — debounced complete.slash, arrow keys / Tab to apply, Esc to close. Parent owns key dispatch via a minimal handleKey ref.

web/src/components/ModelPickerDialog.tsx (new)
Two-stage provider/model picker modal, mirrors ui-tui/src/components/modelPicker.tsx. Search filter across providers + models, global-persist toggle. Confirms by emitting /model <m> --provider <slug> [--global] through the slash pipeline (same code path as typing /model in the composer).

web/src/components/ToolCall.tsx (new)
Expandable tool call row. Collapsed: chevron + name + context + status dot + elapsed. Expanded: context, streaming preview while running, colorized inline_diff, final summary or error. Errors auto-expand. Historical tools from session.resume hide the elapsed badge.

web/src/App.tsx
Logo wrapped in <Link to="/">, Chat entry added to the nav.

web/src/pages/SessionsPage.tsx
Every session row gets a play button, expanded panel gets an "Open in chat" button. Both navigate to /chat?resume=<id> which triggers session.resume and hydrates the transcript before any live events.

web/vite.config.ts
/api proxy configured with ws: true so WebSocket upgrades forward in dev mode. injectDevToken plugin reads HERMES_DASHBOARD_DEV_TOKEN and injects it into the served index.html matching the production bootstrap, so window.__HERMES_SESSION_TOKEN__ is present in both deployment modes.

Tests

tests/hermes_cli/test_web_server.py grows three classes (15 new tests, all passing):

• TestTuiGatewayWebSocket — handshake + gateway.ready, auth rejection (missing/bad token), parse errors, unknown methods, inline + pool handler round-trips, session event routing via the session-bound transport, WS disconnect resets the session's transport back to stdio so stray emits don't crash.
• TestTuiGatewayTransportParity — same RPC over stdio vs WebSocket produces byte-identical response envelopes. Unknown method, inline handler, error envelope, explicit stdio transport — all compared as ===.
• TestTuiGatewayE2EAnyPort — scripted multi-RPC conversation run identically through server.handle_request (direct) and through a live WS; ordered response sequence must match (modulo random session ids). This is the "Ink --tui in any port" check.

Existing tests under tests/tui_gateway/ and tests/test_tui_gateway_server.py all still pass unchanged. Backward compat is preserved because "no transport bound" falls back to the legacy stdio behavior.

Test plan

• scripts/run_tests.sh tests/tui_gateway/ tests/test_tui_gateway_server.py tests/hermes_cli/test_web_server.py — 180 passed
• web/: tsc -b --noEmit clean, eslint clean on all touched files, vite build passes (426 KB / 130 KB gzipped)
• Live stdio smoke vs python -m tui_gateway.entry: gateway.ready ✓, parse error ✓, unknown method ✓, clean exit ✓
• Manual: hermes dashboard, open /chat, stream a response, trigger tool calls, use /help and /model, open a session from /sessions and resume it

Try it

hermes dashboard          # builds web, serves on :9119, click Chat

Dev with HMR:

export HERMES_DASHBOARD_DEV_TOKEN="dev-\$(openssl rand -hex 16)"
hermes dashboard --no-open           # terminal 1
cd web && npm run dev                # terminal 2, :5173

Not in this PR (additive follow-ups)

• Approvals / clarify / sudo / secret prompt UIs — the events already fire and GatewayClient.on(...) has typed hooks for each; just need the UI surfaces.
• Resume picker modal inside /chat (currently you go via /sessions).
• File + image attachments.
• iOS client — same WebSocket protocol; the JSON-RPC surface, token auth model, and event schema all translate directly to URLSessionWebSocketTask + SwiftUI.