feat(daemon): add remote backend JSON-RPC prototype

[slkzgm]

This PR adds an optional daemon prototype that can host CodexMonitor's backend logic in a separate process.

Motivation:

• Unlock a future Remote backend mode (see RFC: Optional remote backend mode (WSL2 daemon / native Windows UI) #54) where the UI can run natively on Windows/macOS while codex (and repo access) stays on another environment (WSL2, dev box, container, etc.).

What’s included:

• New binary: src-tauri/src/bin/codex_monitor_daemon.rs
• Simple line-delimited JSON-RPC protocol over TCP (requests/responses + notifications for events)
• Default bind is 127.0.0.1:<port> and the daemon requires a shared token unless --insecure-no-auth is used.
• Documentation: REMOTE_BACKEND_POC.md

What’s not included:

• No wiring in the desktop app yet (no setting / proxy layer). This is intentionally kept as a standalone building block.

Testing:

• cargo test (in src-tauri/)
• Manual smoke test using REMOTE_BACKEND_POC.md

[slkzgm]

Pushed a small follow-up commit to keep the daemon in sync with the current app-server RPC surface (e.g. turn/start, account/rateLimits/read, skills/list with cwd). This should make the upcoming remote-proxy work usable without having to retrofit the server later.

[Dimillian]

When launching the app in dev

❯ npm run tauri dev

> [email protected] tauri
> tauri dev

     Running BeforeDevCommand (`npm run dev`)

> [email protected] dev
> vite


  VITE v7.3.1  ready in 126 ms

  ➜  Local:   http://localhost:1420/
     Running DevCommand (`cargo  run --no-default-features --color always --`)
error: `cargo run` could not determine which binary to run. Use the `--bin` option to specify a binary, or the `default-run` manifest key.
available binaries: codex-monitor, codex_monitor_daemon
        Info Watching /Users/dimillian/Documents/Dev/CodexMonitor/src-tauri for changes...

[Dimillian]

@codex review

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 6aad947ee5

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[chatgpt-codex-connector]

Handle broadcast lag without killing event stream

In handle_client the event-forwarding loop is while let Ok(event) = rx.recv().await, but tokio::sync::broadcast::Receiver::recv returns Err(Lagged(_)) when the receiver falls behind (e.g., a slow client or a burst of terminal output). This code exits the loop on that error, so the client silently stops receiving all future events even though the TCP connection stays open. Consider handling Err(Lagged) by continuing (and optionally notifying the client) or re-subscribing so a temporary backlog doesn’t permanently drop the event stream.

Useful? React with 👍 / 👎.

[slkzgm]

Pushed two small follow-ups addressing the dev run issue + the event stream robustness feedback:

• Fixed npm run tauri dev (cargo run ambiguity with 2 bins) by setting default-run = "codex-monitor" in src-tauri/Cargo.toml.
• Made the daemon event-forwarding task resilient to broadcast::RecvError::Lagged(_) (now continues on lag and only breaks on Closed / disconnect), so a slow client/burst won't permanently stop events.

Commits: fc62fac, 42b2f0b.

[slkzgm]

CI was failing because upstream main added a codex_home: Option parameter to spawn_workspace_session (GitHub Actions builds the PR merge commit).

I rebased this branch on current main (v0.6.8) and updated the daemon to pass the resolved legacy .codexmonitor dir as CODEX_HOME (or None otherwise). CI should now be green again.

[Dimillian]

Thanks!