fix(desktop): don't kill a backend that is still starting - #1809
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The launcher waited a flat five minutes from spawn for the backend to report ready, then killed it and tried again. On a host where the cold start genuinely takes longer — the reporter's project lived on a mapped network drive, and `import torch` off one is slow the first time, as is a first CUDA load or a cold spinning disk — that deadline expired *while the backend was still importing*. The respawn threw away the warm page cache and raced the same clock, so the app could never start, and it blamed the backend: "the backend never reported ready". Launching that same backend by hand reached ready in well under a minute once the cache was warm. A backend answering `/startup/progress` with `status: "starting"` is not one we have to guess about: it bound its socket, it is serving HTTP, and it is naming the step it is on. Killing it cannot make the retry faster, and the launcher knows nothing the user doesn't. So keep waiting while it answers, and keep narrating each step. The budget still governs silence — nothing answering, or a self-reported `failed` — where a slow backend and a wedged one really are indistinguishable and the existing stderr-tail failure is the right answer. The splash needed the same correction. Its stall watchdog keys on `bootstrap_status`, which sits on `starting_backend` for the whole of a slow start, so it would have called the launch stuck at six minutes anyway; the proof of life arrives on the separate `bootstrap-log` stream. Output now counts as activity, and a genuinely silent backend still trips the watchdog so the info-less spinner of #879 stays fixed. Fixes #1791. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01HR6J9zKQop9TGGVUwjypnF
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| Filename | Overview |
|---|---|
| frontend/src-tauri/src/bootstrap.rs | Adds generation-based startup-wait preemption and guards timeout publication against stale launch attempts. |
| frontend/src-tauri/src/tools.rs | Handles the macOS process-group signaling race while preserving errors for live, reaped, or unverifiable roots. |
| frontend/src-tauri/tests/backend_lifecycle.rs | Verifies that lifecycle takeover can preempt a launch before its readiness polling begins. |
| frontend/src/components/BootstrapSplash.jsx | Treats backend bootstrap log output as activity for the splash stall watchdog. |
| frontend/src/test/BootstrapSplashSlowBackendStall.test.jsx | Covers prolonged narrated startup and the existing silent-start stall behavior. |
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Included review availability: Your plan provides up to 10 included reviews per hour; 0 remain after this review. 📝 WalkthroughWalkthroughThe desktop bootstrap now tracks backend progress and log activity, supports readiness-wait preemption, and suppresses stale timeout publication. macOS process shutdown now accepts EPERM only after verified unreaped process exit. ChangesBackend startup lifecycle
macOS process shutdown
Estimated code review effort: 4 (Complex) | ~60 minutes Merge Risk: ⚪ Minimal · up to Slow but active backend startups can continue without premature restart, while silent or failed startups still time out. Retry avoids stale timeout states, and macOS shutdown preserves permission failures unless the exiting root process is verified. 🚥 Pre-merge checks | ✅ 6 | ❌ 3❌ Failed checks (3 warnings)
✅ Passed checks (6 passed)
Full details: Docstring CoverageExplanation Docstring coverage is 77.14% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 35 functions across 5 files. (2 skipped: 2 unsupported.) Full details: Cross-Platform Default ParityExplanation The PR changes default shutdown behavior only on macOS. Resolution Make the shutdown result parity-preserving across macOS, Windows, and Linux, or gate the Darwin
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In `@frontend/src-tauri/src/bootstrap.rs`:
- Around line 853-855: Update the startup progress handling around last_step so
repeated starting responses for the same non-empty step periodically emit a
throttled liveness signal, keeping BootstrapSplash alive during long-running
steps without emitting on every response. Preserve the existing first-emission
behavior for new steps, and add a regression test covering an unchanged step.
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Greptile's P1 on #1809, and it is right. `launch_backend_and_wait` holds `BackendState::lifecycle` around the entire launch, including the readiness wait — which this branch just made unbounded for as long as the backend answers `/startup/progress`. Retry, Clean & Retry, reset and uninstall all need that same lock, so on a slow start the user's own escape hatch would block behind the wait instead of interrupting it: an app with no way out, which is worse than the early kill the branch set out to remove. Every flow that is about to take lifecycle ownership now bumps a generation counter first, before reaching for the lock. The waiting loop snapshots that counter once its caller holds ownership — so a bump that predates it is not mistaken for a preemption — and stands down within one 500 ms poll when it changes, releasing the lock for whoever asked. That also settles what happens at the splash's six-minute stall budget: it flips to failed and offers Retry and the logs, and Retry now actually works, while its /health recovery poll still walks straight into the app if the slow start finishes first. Either way the user gets out. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01HR6J9zKQop9TGGVUwjypnF
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Inline comments:
In `@frontend/src-tauri/src/bootstrap.rs`:
- Around line 689-691: Capture the wait generation before acquiring
BackendState::lifecycle, then re-check it after ownership is obtained so a Retry
preemption during startup cannot be accepted by the old wait. Update the
relevant bootstrap flow and add a deterministic regression test covering
preemption in this interval, verifying Retry obtains lifecycle ownership.
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In `@frontend/src-tauri/tests/backend_lifecycle.rs`:
- Line 1776: Update the test cleanup around the bootstrap thread and wait_until
assertion so every exit path writes release, then joins bootstrap before
asserting the wait result. Ensure timeout handling does not detach the thread
while it still holds BackendState.lifecycle, while preserving the existing
success assertion behavior.
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Fixes #1791.
The report
The Windows desktop app sits at
starting_backendforever and then reports "the backend never reported ready". The same backend, launched by hand withuv run python backend/main.py, reachesPreload complete — model readyin 20–60 s — and once it is running, the GUI attaches to it and works fine. Self-check passes 11/11, including deep synthesis.The reporter's project lives on
Z:\Omnivoice\project— a mapped network drive.Root cause
spawn_backend_until_readywaited a flatstartup_budget()(300 s) from spawn:On a host where the cold start genuinely exceeds that —
import torchoff a network drive, a first CUDA DLL load, a cold spinning disk — the deadline expires while the backend is still importing. The launcher then kills the child and respawns it; the respawn discards the warm page cache and races the same clock, so it can never converge. The reporter's thread dumps show exactly this: the startup worker insidetorch.__init__for the whole window, and the log carriesPrevious backend run (pid …, version 0.5.1) ended uncleanlyfollowed by another spawn.The loop already polled
/startup/progress— it just used the answer for narration only, never to decide whether to keep waiting.The fix
A backend answering
status: "starting"is not one we have to guess about: it bound its socket, it is serving HTTP, and it is naming the step it is on. Killing it cannot make the retry faster, and the launcher has no information the user lacks. So the wait now keys on liveness rather than a wall clock:The budget still governs silence — nothing answering on the port, or a self-reported
failed— because there a slow backend and a wedged one really are indistinguishable, and the existing failure path (stderr tail + Retry) is the right answer. That path is unchanged.The escape hatch stays deliberate rather than clock-driven: the splash surfaces Retry and the logs on its own stall budget, and its
/healthrecovery poll walks straight into the app if the slow start does finish.The splash needed the same correction
useBootstrapStage's stall watchdog keys onbootstrap_status, which sits onstarting_backendfor the entire slow start — so it would have declared the launch stuck at six minutes regardless of what Rust did. The narration that proves the backend is alive ("Loading ML runtime (PyTorch)…") arrives on the separatebootstrap-logevent stream. Output now counts as activity. A genuinely silent backend still trips the watchdog, so the info-less infinite spinner of #879 stays fixed.Tests
Both fail before / pass after, verified locally.
bootstrap.rs::a_backend_that_is_still_starting_is_never_timed_out— astartingbackend is kept at 3600 s; silence still expires exactly at the budget;failedand an unrecognised status get no extension.BootstrapSplashSlowBackendStall.test.jsx— 20 minutes ofstarting_backendwith a step arriving every 4 minutes never flips tofailed; a silent 6 minutes still does.Full suites on this branch: 2597 frontend, 237 Rust lib + 24
backend_lifecycle. No doc describes the readiness budget, so there is no docs-sync impact.Not fixed here
The reporter also observed PostHog DNS/TLS timeouts on their restricted network and an unreachable
huggingface.co. Those are worth their own look, but they are not what failed the launch — the backend was making progress the whole time and was killed anyway.🤖 Generated with Claude Code
https://claude.ai/code/session_01HR6J9zKQop9TGGVUwjypnF
The desktop launcher now keeps healthy slow backends alive while startup progress or
bootstrap-logactivity continues, and Retry can preempt stale readiness waits. Silent or failed backends retain timeout handling, while Darwin shutdown now verifies process exit before accepting permission errors. Review whether continuous progress could delay failure detection for an unhealthy backend.