fix: keep dashboard importable without Unix PTY modules

[bgmbgm94]

Summary

Native Windows is documented as an early-beta runtime, but the dashboard /chat embedded terminal path is still the main native-Windows gap because it depends on POSIX PTY primitives. This PR keeps the rest of the dashboard usable and makes the /chat failure mode friendlier while testing there:

• Guard Unix-only fcntl and termios imports in hermes_cli.pty_bridge
• Keep hermes_cli.web_server importable when PTY support is unavailable
• Preserve existing Linux/macOS behavior: PtyBridge.is_available() remains true only when ptyprocess, fcntl, and termios are all available and the platform is not native Windows
• Add a regression test that simulates missing Unix PTY modules and verifies non-PTY dashboard routes can still import while PTY spawn reports unavailable
• Strengthen the embedded-chat WebSocket test so PTY unavailability sends a clear message and closes the socket instead of crashing the dashboard server

Related to #5246 and complements #5247. That PR covers tools/memory_tool.py plus guarded SIGKILL lookups; this PR covers the dashboard chat PTY bridge import path, which is a separate fcntl/termios import site.

Testing

• python -m pytest tests/hermes_cli/test_web_server.py::TestNativeWindowsPtyImportFallback::test_web_server_imports_when_unix_pty_modules_are_missing tests/hermes_cli/test_web_server.py::TestPtyWebSocket -q -o addopts=
  • 12 passed
• python -m pytest tests/hermes_cli/test_web_server.py -q -o addopts=
  • 138 passed
• ruff check hermes_cli/pty_bridge.py tests/hermes_cli/test_web_server.py
  • All checks passed!
• Native Windows Python smoke via the Hermes Windows venv:
  • platform= win32
  • fcntl= None
  • termios= None
  • pty_available= False
  • web_server_app= True

Note: I could not run the pytest target inside the Windows Hermes venv because that venv does not have pytest installed. The Linux/WSL venv ran the regression suite above, and the native Windows Python smoke directly verified this import path with missing fcntl/termios.

[Copilot]

Pull request overview

Improves the dashboard’s robustness on native Windows / non-POSIX environments by making the PTY bridge optional at import-time, so hermes_cli.web_server can still load and serve non-PTY routes even when Unix PTY modules aren’t present.

Changes:

• Guard fcntl / termios imports in hermes_cli.pty_bridge and make PTY availability depend on ptyprocess + fcntl + termios + non-Windows platform.
• Add a regression test ensuring hermes_cli.web_server remains importable when Unix PTY modules are missing and that PTY spawn reports unavailable.
• Strengthen the /api/pty WebSocket test to assert the endpoint sends an error message and then closes cleanly when PTY spawn is unavailable.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
hermes_cli/pty_bridge.py	Makes Unix-only dependencies optional at import-time and refines the PTY availability gate.
tests/hermes_cli/test_web_server.py	Adds regression coverage for missing Unix PTY modules and tightens WebSocket failure-mode assertions.

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[bgmbgm94]

Thanks, agreed — the unavailable path should keep the graceful import behavior but still surface an actionable spawn-time reason. I'll update the spawn error to distinguish native Windows from missing Unix PTY modules and add regression coverage for that message.

[teknium1]

Closing as superseded by #42251, which adds an actual ConPTY backend (hermes_cli/win_pty_bridge.py) rather than only guarding the import. The graceful-degradation idea was right — your PR was the first to make the dashboard's non-chat tabs survive a POSIX-only-pty_bridge import on Windows — but the real fix is to make the chat tab itself work, which #42251 does. Thanks for the early push on this.

[bgmbgm94]

Thanks for the clear explanation and for carrying the Windows dashboard fix forward in #42251. Agreed that the ConPTY backend is the right final shape here, so I’m closing this as superseded.

[bgmbgm94]

Thanks for the clear explanation and for carrying the Windows dashboard fix forward in #42251. Agreed that the ConPTY backend is the right final shape here, so I’m closing this as superseded.