First increment of the observability epic (T-425), the productive pivot after
the ConPTY freeze refused to reproduce on CI: if we can't reproduce it, make
the next occurrence leave evidence.
- FileLogSink (lib/kernel/src/file_log_sink.dart): synchronous, crash-survivable
LogSink. Appends each record as one JSON line to a size-rotated file; fsyncs
warn/error + risky-source (pty/ffi/conpty/watchdog) records immediately so the
last breadcrumb is on disk before a hard death, batches the rest on a timer.
Never throws. Flutter-free → unit-tested under dart test against a temp dir.
- logDirectory() (paths.dart): persistent per-platform log dir (LOCALAPPDATA /
~/Library/Logs / $XDG_STATE_HOME) — durable across reboot, unlike the
ephemeral socketDirectory.
- resolveLogLevel() (log.dart): the requested dev/prod toggle. CLIDE_LOG
dart-define → CLIDE_LOG env → app.log.level setting → warn(release)/info(debug).
Lenient parse; an invalid source falls through.
- Boot wiring (facade.boot + main.dart): FileLogSink leads the sink chain (so a
crash records before the volatile stderr/ring sinks) and the resolved level
sets Logger.minLevel.
Tests: FileLogSink (JSON shape, error/stack, rotation cap, append-across-restart,
timer-cancel), resolveLogLevel precedence + fall-through, logDirectory per-OS.
Coverage gate 95.11%.
Follow-ups under T-425: live toggle CLI/command/chip (T-433), FFI breadcrumbs
(T-434), watchdog isolate (T-435), CI artifact wiring (T-436).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
jpmschweitzerandClaude Opus 4.8
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