fix(daemon): timeout WebSocket serial opens

[zackees]

Summary

• wrap WebSocket serial attach open_port(...) in a 30 second timeout matching HTTP monitor/deploy monitor behavior
• send a serial error frame on timeout/error and return from the WebSocket handler so the socket closes and the pending attach guard drops
• add regression coverage with an injected hung open future proving the timeout error and pending attach cleanup

Closes #977

Verification

• soldr --no-cache cargo test --target-dir target-codex-977-nocache -p fbuild-daemon --no-default-features handlers::websockets -j 2 (captured pass: 8 passed)
• soldr --no-cache cargo check --target-dir target-codex-977-nocache -p fbuild-daemon --no-default-features -j 2
• soldr cargo fmt --all --check
• git diff --check

Note: after the captured focused test pass, I made a readability-only cleanup in the test helper and re-ran soldr cargo fmt --all --check plus git diff --check; repeated no-cache/cached test capture attempts after that cleanup exceeded the local tool timeout while compiling or left orphaned Cargo wrappers, so I stopped the orphaned verification process tree.

Summary by CodeRabbit

• Bug Fixes

  • WebSocket serial attach now times out if opening a port takes too long, instead of waiting indefinitely.
  • Users now get a clearer error message when the serial port can’t be opened in time, including a helpful explanation and deadline details.
  • If the open attempt times out, the connection sends an error response and cleans up pending attach state properly.

• Tests

  • Added coverage for timeout handling and cleanup behavior during serial attach.

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 07611cd3-244f-4fe4-97c2-7dee09370125

📥 Commits

Reviewing files that changed from the base of the PR and between 3cbc49d and 3956201.

📒 Files selected for processing (2)

• crates/fbuild-daemon/src/handlers/websockets.rs
• crates/fbuild-daemon/src/handlers/websockets_tests.rs

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📝 Walkthrough

Walkthrough

Adds a WS_SERIAL_OPEN_PORT_TIMEOUT (30s) constant and helper functions wrapping the WebSocket serial attach open_port call in tokio::time::timeout, replacing the unbounded await with a timeout-bounded version that sends an error frame on failure. Adds regression tests for timeout behavior and pending-attach cleanup.

Changes

WebSocket serial open_port timeout

Layer / File(s)	Summary
Timeout helper and constant crates/fbuild-daemon/src/handlers/websockets.rs	Adds Future import, WS_SERIAL_OPEN_PORT_TIMEOUT (30s) constant, format_timeout_for_error, and await_ws_serial_open_port to wrap open_port futures with tokio::time::timeout.
Attach handler wiring crates/fbuild-daemon/src/handlers/websockets.rs	Replaces the direct open_port(...).await call in the attach path with await_ws_serial_open_port(...), using its formatted error string while preserving the error-frame send/early-return behavior.
Timeout and pending-attach cleanup tests crates/fbuild-daemon/src/handlers/websockets_tests.rs	Adds tokio tests confirming await_ws_serial_open_port times out with a descriptive error, and that the pending-attach guard clears pending-attach count/info and busy_reason after a timeout.

Estimated code review effort: 2 (Simple) | ~15 minutes

Sequence Diagram(s)

sequenceDiagram
  participant Client
  participant WebSocketHandler
  participant SerialManager

  Client->>WebSocketHandler: Attach message
  WebSocketHandler->>SerialManager: open_port(port, baud, client_id) with 30s timeout
  alt open_port completes
    SerialManager-->>WebSocketHandler: Ok/Err result
  else timeout elapses
    SerialManager-->>WebSocketHandler: (no response)
    WebSocketHandler-->>Client: SerialServerMessage::Error (timeout)
  end
  WebSocketHandler->>WebSocketHandler: drop pending-attach guard

Loading

Related issues: #977 (direct)

Suggested labels: daemon, websockets, timeout

Suggested reviewers: none identified

🐰 A timer ticks while ports awaken slow,
Thirty seconds granted, then the plug must go,
Guards drop quietly, counts return to naught,
No more wedged whispers where the daemon's caught.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/977-ws-open-timeout

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