0385 — The abandoned-routines tracking map stays unbounded; no config knob

Context. pkg/consumer/metrics/abandoned_routines.go carried a comment proposing to bound its tracking map with a ConcurrentBoundedRingBuffer-style structure, on the premise that the map could grow without limit.

Decision. Not bounded — the premise didn’t survive analysis. An entry exists only while its abandoned goroutine is still running (Remove fires when the routine finally returns), so the map exactly mirrors live abandoned goroutines: ~50 bytes per entry versus at least 2KB of goroutine stack plus whatever the zombie pins (the deserialized work message, the timeout ctx). Bounding the map would bound under 3% of the leak while the 97% can’t be reclaimed anyway, and evicting a live key breaks the metrics: the routine’s eventual Remove finds nothing, the otel outstanding counter drifts upward permanently, and the latency sample is lost.

Consequences. The config-vs-constant question dies with the bound — no bound, no knob. Rejected: the ring-buffer structure — selfClearLatencies can drop old samples harmlessly, but the map is a set of live keys, not a window of history, so the structure doesn’t transfer. The analysis did surface a real unbounded-growth path, an Add/Remove ordering race, fixed separately.