Exposes hermes --tui over a PTY-backed WebSocket so the dashboard can
embed the real TUI rather than reimplement its surface. The browser
attaches xterm.js to the socket; keystrokes flow in, PTY output bytes
flow out.
Architecture:
browser <Terminal> (xterm.js)
│ onData ───► ws.send(keystrokes)
│ onResize ► ws.send('\x1b[RESIZE:cols;rows]')
│ write ◄── ws.onmessage (PTY bytes)
▼
FastAPI /api/pty (token-gated, loopback-only)
▼
PtyBridge (ptyprocess) ── spawns node ui-tui/dist/entry.js ──► tui_gateway + AIAgent
Components
----------
hermes_cli/pty_bridge.py
Thin wrapper around ptyprocess.PtyProcess: byte-safe read/write on the
master fd via os.read/os.write (not PtyProcessUnicode — ANSI is
inherently byte-oriented and UTF-8 boundaries may land mid-read),
non-blocking select-based reads, TIOCSWINSZ resize, idempotent
SIGHUP→SIGTERM→SIGKILL teardown, platform guard (POSIX-only; Windows
is WSL-supported only).
hermes_cli/web_server.py
@app.websocket("/api/pty") endpoint gated by the existing
_SESSION_TOKEN (via ?token= query param since browsers can't set
Authorization on WS upgrades). Loopback-only enforcement. Reader task
uses run_in_executor to pump PTY bytes without blocking the event
loop. Writer loop intercepts a custom \x1b[RESIZE:cols;rows] escape
before forwarding to the PTY. The endpoint resolves the TUI argv
through a _resolve_chat_argv hook so tests can inject fake commands
without building the real TUI.
Tests
-----
tests/hermes_cli/test_pty_bridge.py — 12 unit tests: spawn, stdout,
stdin round-trip, EOF, resize (via TIOCSWINSZ + tput readback), close
idempotency, cwd, env forwarding, unavailable-platform error.
tests/hermes_cli/test_web_server.py — TestPtyWebSocket adds 7 tests:
missing/bad token rejection (close code 4401), stdout streaming,
stdin round-trip, resize escape forwarding, unavailable-platform ANSI
error frame + 1011 close, resume parameter forwarding to argv.
96 tests pass under scripts/run_tests.sh.
