FA-42679 / Listener lifecycle / Member archive

Merge reports delayed errors before all inner callbacks finish · case 04

Merge reports delayed errors before all inner callbacks finish; the returned lifecycle plan violates the stated transition contract.

Member previewVariant 4 · 3 implementations · 7 checks per implementation

Case contract

Plan a bounded-concurrency merge observer. Active inner IDs occupy slots, reserved synchronous starts also occupy slots, and pending outer items are FIFO. Fill only free slots; completion removes the matching inner ID. Outer completion waits for active, reserved and pending work. Fail-fast cancels siblings; delay-error retains them and accumulates errors until all work drains. New delayed-error entries are [failing_inner_id,error] records; preserve the supplied done identity instead of storing only the message. Inputs are finite state snapshots, including transitional and stale states; output fields are the exact independent actions/metadata defined by the corrected expression table. Numeric fixture capacities and counts vary with N. Field definitions, each independently computed from the input snapshot: slots = max(0,s['limit']-len(s['active'])-s['reserved']); starts = s['pending'][:max(0,s['limit']-len(s['active'])-s['reserved'])]; pending = s['pending'][max(0,s['limit']-len(s['active'])-s['reserved']):]; active = [x for x in s['active'] if x!=s['done']]; finish = s['outer_done'] and not s['active'] and not s['pending'] and s['reserved']==0; cancel_siblings = s['cancel'] or (s['error'] is not None and not s['delay_error']); errors = list(s['errors'])+([[s['done'],s['error']]] if s['error'] is not None else []); report_delayed = s['delay_error'] and bool(s['errors']) and s['outer_done'] and not s['active'] and not s['pending'] and s['reserved']==0; unknown_completion = s['done'] is not None and s['done'] not in s['active']; release_slots = int(s['done'] is not None and s['done'] in s['active'])

Why this case matters

Observer implementations need to preserve this state while subscriptions enter, execute, and leave their lifecycle.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
transition 0	`{"active": ["a", "b"], "cancel_siblings": true, "errors": ["old", ["missing", "bad"]], "finish": false, "pending": ["x", "y", "z"], "release_slots": 0, "report_delayed": true, "slots": 0, "starts": [], "unknown_completion": true}`	`{"active": ["a", "b"], "cancel_siblings": true, "errors": ["old", ["missing", "bad"]], "finish": false, "pending": ["x", "y", "z"], "release_slots": 0, "report_delayed": false, "slots": 0, "starts": [], "unknown_completion": true}`	Failed

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