FA-41659 / Listener lifecycle / Member archive

An inner cancellation erases the outer callback context · case 04

An inner cancellation erases the outer callback context; the returned lifecycle plan violates the stated transition contract.

Member previewVariant 4 · 3 implementations · 8 checks per implementation

Case contract

Plan a nested observer emission with bounded depth. A nested event queues when serialization is enabled; otherwise it opens a child frame if below the limit. Preserve the outer event/context, unwind exactly one frame, and drain deferred events only after the outermost callback completes. A cancelled inner frame never cancels its parent. 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: queue = s['serial'] and s['depth']>0 and s['event'] is not None; enter = s['event'] is not None and not(s['serial'] and s['depth']>0) and s['depth']<s['limit']; outer_event = s['outer']; context = s['context']; unwind = s['frames'][:-1] if s['complete'] else list(s['frames']); drain = list(s['pending']) if s['complete'] and s['depth']<=1 else []; parent_cancel = False; overflow = s['event'] is not None and s['depth']>=s['limit'] and not(s['serial'] and s['depth']>0); next_depth = max(0,s['depth']-int(s['complete'])); queued_order = list(s['pending'])+([s['event']] if s['serial'] and s['depth']>0 and s['event'] is not None else [])

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	`{"context": null, "drain": [], "enter": false, "next_depth": 0, "outer_event": null, "overflow": true, "parent_cancel": false, "queue": false, "queued_order": ["a", "b"], "unwind": ["root"]}`	`{"context": "ctx", "drain": [], "enter": false, "next_depth": 0, "outer_event": null, "overflow": true, "parent_cancel": false, "queue": false, "queued_order": ["a", "b"], "unwind": ["root"]}`	Failed

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