FA-41738 / Listener lifecycle / Member archive

Ignored prevent-default calls are not diagnosed for passive listeners · case 03

Ignored prevent-default calls are not diagnosed for passive listeners; the returned lifecycle plan violates the stated transition contract.

Member previewVariant 3 · 3 implementations · 8 checks per implementation

Case contract

A stipulated non-UI event path is root-to-target. Capture visits ancestors in that order; bubble visits ancestors in reverse only for bubbling events. Target is visited once. stopPropagation prevents later nodes but not sibling callbacks on the current node; stopImmediate prevents both. Only cancelable, nonpassive listeners may prevent the default action. A prior prevented marker is monotonic. 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: capture = s['path'][:-1]; bubble = list(reversed(s['path'][:-1])) if s['bubbles'] else []; target = s['path'][-1] if s['path'] else None; next_node = not s['stopped'] and not s['immediate']; siblings = 0 if s['immediate'] else s['siblings']; default_prevented = s['prevented'] or (s['prevent'] and s['cancelable'] and not s['passive']); default_run = not s['prevented'] and not(s['prevent'] and s['cancelable'] and not s['passive']); current_target = s['current']; path_copy = list(s['path']); prevent_ignored = s['prevent'] and (s['passive'] or not s['cancelable'])

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	`{"bubble": ["middle", "root"], "capture": ["root", "middle"], "current_target": "root", "default_prevented": false, "default_run": true, "next_node": false, "path_copy": ["root", "middle", "target"], "prevent_ignored": false, "siblings": 9, "target": "target"}`	`{"bubble": ["middle", "root"], "capture": ["root", "middle"], "current_target": "root", "default_prevented": false, "default_run": true, "next_node": false, "path_copy": ["root", "middle", "target"], "prevent_ignored": true, "siblings": 9, "target": "target"}`	Failed

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