fix(cli): a refused UI configuration is not a failed daemon start

[liuchong]

The bug

daemon start reports failure for a daemon that started and is serving.

test / test-windows-guards goes red with:

RED: `daemon start` after the crash must launch a FRESH daemon:
error: the daemon did not accept the UI configuration; browser was not opened
RED (tests/windows/test_daemon_stability.py): section_crash_recovery failed

That message has exactly one source, in main_run_daemon_ctl. Reaching it means the daemon is already up — the comment directly above it says so, and the handshake is sent over the very control connection that satisfied the daemon's no-client startup window. Only the UI configuration came back short.

Root cause

The handshake is two requests, each bounded by MAIN_CONNECT_TIMEOUT_MS (one second), and missing that window was treated as a failed start.

One second is thin on a loaded machine, and section_crash_recovery manufactures exactly that state: it hard-kills a daemon and immediately starts a fresh one, on a runner still reclaiming the dead process's resources. This is the same environment #1772 addressed, but a different bounded wait — #1772 fixed the startup-transition lock, and this path sits downstream of it. The failure reproduces on a branch that already carries #1772.

The change

Whether a refused UI configuration is fatal now depends on what was asked for.

--port and --open make the UI the point of the command, so they keep the existing nonzero exit. A bare daemon start asks for a daemon and got one, so it warns and succeeds. It also skips the UI-warming notice, which would otherwise announce a port that nothing is serving.

Verification

A seam (CBM_TEST_DAEMON_UI_CONFIG_REFUSED, compiled out without TEST_SEAMS=1) forces the refusal, because reproducing it for real needs a machine loaded enough to miss a bounded handshake — not a state a test can ask for.

tests/windows/test_daemon_lifecycle.py covers both halves of the contract and reports a precondition skip against a non-UI binary. Checked locally against a scripts/build.sh --with-ui TEST_SEAMS=1 build:

• with the fix: green, both new assertions pass
• with the seam kept but the decision reverted to its previous unconditional failure: red on a refused UI configuration must not fail daemon start
• against a non-UI binary: the new section skips, the existing ones stay green

lint-format and lint-cppcheck are clean.

The underlying timing only occurs on Windows CI, so the guard's behaviour there is what this PR is asking to confirm.

[github-actions]

Thanks for opening this — it has been seen, and it is queued.

This note is automated, but it is not a brush-off: it exists so you know where your PR stands instead of having to guess from silence.

Current review status: working through a backlog. 0.9.1-rc.1 is out, so the release freeze that held reviews is over — but it left a large queue of open pull requests behind it, and we are reading through them oldest-first. The background is in discussion #1144.

What that means for this PR, concretely:

• It will not be closed for inactivity. No stale bot touches pull requests here.
• It may still sit a while before a human reads it. That is on us, not on you.
• Older PRs are read first, so a recent one is not being skipped — it is behind a queue.

Things that will genuinely speed it up whenever review does happen:

• Keep it rebased on main — the tree is moving quickly right now, and a conflicting branch cannot be reviewed as the diff you intended.
• Get CI green, or say which failures you believe are pre-existing.
• Keep the change to one claim. Bundled features and refactors get split before they get merged, which costs you a round trip.
• Every commit needs a sign-off (git commit -s) — CI enforces DCO.

If this fixes a bug, a reproduction we can run is worth more than a description of the symptom.

Thanks for contributing, and sorry in advance for the wait.