feat(logging): record renderer and helper process crashes

[chris-yoshih]

Description

Another suggestion — independent of #2971, either can stand alone.

render-process-gone and child-process-gone have no handlers anywhere in the
repo. When a renderer, GPU, or utility process dies, no main-process code path
runs: the window white-screens or a feature quietly stops working, and
uncaughtException never fires, so registerProcessErrorLogging doesn't see it
either. emdash.log just ends mid-session.

That's the worst case for the failure mode #80's memory watchdog exists for. An
OS-killed renderer is exactly what leaves no trace — the evidence is a platform
crash report (a macOS JetsamEvent, say), outside the app, kept only if the OS
felt like it. This puts the cause in emdash's own log next to the rest of the
session, so reason and exitCode are one grep away.

clean-exit is dropped rather than recorded. Electron reports it for every
helper that terminates normally at shutdown, so logging it would mean a burst of
errors on every ordinary quit. For a renderer death the report also carries the
WebContents URL, which separates the app window from a browser-pane webview —
a page in the in-app browser crashing says nothing about emdash.

Shape. reportRenderProcessGone / reportChildProcessGone are pure
functions returning a message plus fields, or null for a clean exit — no
Electron import, so the filtering and field selection are directly testable.
registerProcessCrashLogging(app, log) is the wiring, typed against a narrowed
ProcessCrashEventSource interface rather than Electron.App so a test can
hand it a stub emitter. Same split as dev-worktree-profile.ts and
reap-dev-profiles.ts. index.ts gains one import and one call, next to the
existing registerProcessErrorLogging.

One thing worth flagging: reading contents.getURL() on a WebContents that is
already tearing down can throw, so it's wrapped and the URL is simply omitted
when unavailable — the crash still gets logged.

Related issues

None filed. It came up while reading #80 — the watchdog catches the run-up to a
memory kill, but if the kill lands anyway there's nothing in the log to confirm
what happened.

Testing

• oxfmt --check, oxlint, tsgo --noEmit on apps/emdash-desktop — all clean.
• vitest run --project node — 283 files / 2032 tests pass, including 10 new
  ones: oom / crashed / killed renderer reasons, clean-exit suppressed
  on both events, a missing URL falling back to undefined, child-process type
  and serviceName passthrough, and the registration seam driven by a stub
  emitter (both handlers registered, both firing, clean exits producing no log
  call).
• Not run: the full workspace pnpm run test across every project. No manual
  crash reproduction — I didn't want to guess at forcing an OOM kill on a real
  session, so the Electron event payloads are taken from the documented shapes
  and exercised through the stub rather than from a live crash. If you'd rather
  see a real one in a log before taking this, that's fair.

Screenshot/Recording (if applicable)

n/a — log output only.

Checklist

• I kept this PR small and focused
• I ran a self-review before opening this PR
• I ran the relevant local checks or explained why not
• I updated docs when behavior or setup changed — no docs describe log contents
• I added or updated tests when behavior changed, or explained why not
• I only added comments where the logic is not obvious
• I used Conventional Commits for commit messages and the PR title

[greptile-apps]

Greptile Summary

Adds app-wide logging for abnormal Electron renderer and helper-process exits.

• Records process reason, exit code, renderer URL, and helper metadata through the existing file logger.
• Suppresses normal clean-exit events and tolerates destroyed WebContents instances.
• Registers the handlers during main-process startup and adds focused unit and wiring tests.

Confidence Score: 5/5

The PR appears safe to merge, with no concrete correctness or security failures identified in the changed paths.

The new listeners match the intended Electron process-gone event flow, use the initialized non-throwing logger, suppress ordinary teardown events, and retain crash logging when renderer URL lookup fails.

Important Files Changed

Filename	Overview
apps/emdash-desktop/src/main/app/process-crash-logging.ts	Adds focused process-exit report builders and Electron event registration with clean-exit filtering and safe URL lookup.
apps/emdash-desktop/src/main/app/process-crash-logging.test.ts	Covers renderer and helper crash reports, clean-exit suppression, registration wiring, and unavailable renderer URLs.
apps/emdash-desktop/src/main/index.ts	Registers process crash logging after file-logger initialization during synchronous main-process setup.

_{Reviews (1): Last reviewed commit: "feat(logging): record renderer and helpe..." | Re-trigger Greptile}