Module diag 

Process-wide diagnostics: capture every WARN+ tracing event and panic.

Each one ends up in (a) the rolling log file, (b) a global ring buffer surfaced through MetricsSnapshot → the F12 panel and fmf stats, and (c) any registered sinks (the FFI forwards them as ENGINE_ERROR events to the UI). The layer responsible for the “don’t go silent” arm of “don’t crash / don’t hang / don’t go silent”.

Structs

DiagLayer

Routes WARN/ERROR tracing events into the diagnostics ring + sinks. Events with target: "panic" are classified as panics.

ErrorEvent

One captured diagnostic event: the unit stored in the ring and fanned out to sinks.

FieldGrab 🔒

SinkGuard

Lifetime handle for a registered sink; dropping it unregisters the sink.

Enums

Severity

Severity class of a captured diagnostic event, in ascending order.

Constants

RING_CAP 🔒

Statics

LOG_GUARD 🔒

RING 🔒

SEQ 🔒

SINKS 🔒

SINK_IDS 🔒

START 🔒

Functions

error_chain

Full error cause chain as one line.

init_diag

The one diagnostics bootstrap: file/stderr logging + panic capture + diag-ring wiring, idempotent — FFI fmf_engine_create, the service entry points and the CLI all call exactly this (ADR-0018).

init_logging

Initialize process-wide logging once.

install_panic_hook

Route every panic (any thread) through tracing with a backtrace, so it reaches the log file, the ring and the UI. Idempotent.

recent_errors

Snapshot of the diagnostics ring (oldest first), capped at the ring size.

record

Record one diagnostic event (ring + sinks). Normally reached via the tracing layer rather than called directly.

register_sink

Register a fan-out target for new error events; dropping the guard unregisters it (the FFI ties this to the engine handle’s lifetime).

resolve_log_dir

Resolves the engine log directory.

Type Aliases

Sink 🔒