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FA-35881 / Tab interfaces / Open access

Collapse empty pane: collapse trigger · case 01

The tab workspace reports an incorrect collapse trigger.

Verified by executionVariant 1 · 7 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The collapse trigger decision uses x['remaining']==0 instead of x['remaining']==0 and not x['root'].

THE FAILURE

The collapse trigger decision uses x['remaining']==0 instead of x['remaining']==0 and not x['root'].

Unsuccessful approach: The partial repair not x['root'] still violates a workspace boundary or normal case.

Case contract

A pane disappears only after its last tab closes; promote its sibling subtree, remove the separator, transfer active-pane ownership and retain sibling extent.

Why this case matters

Offline tab/panel workspace behavior; no browser or desktop framework is emulated.

1 / The failure

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x):
    r0 = x['remaining']==0
    r1 = x['remaining']==0 and x['root']
    r2 = x['sibling'] if x['remaining']==0 and not x['root'] else x['pane']
    r3 = x['gutter'] if x['remaining']==0 and not x['root'] else 0
    r4 = x['sibling'] if x['remaining']==0 and not x['root'] and x['active']==x['pane'] else x['active']
    r5 = x['width']+x['sibling_width']+x['gutter'] if x['remaining']==0 and not x['root'] else x['sibling_width']
    return [r0,r1,r2,r3,r4,r5]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = {1: [({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 300, 'sibling_width': 200, 'gutter': 8}, [True, False, 'q', 8, 'q', 508]), ({'remaining': 1, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 300, 'sibling_width': 200, 'gutter': 8}, [False, False, 'p', 0, 'p', 200]), ({'remaining': 0, 'root': True, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 300, 'sibling_width': 200, 'gutter': 8}, [False, True, 'p', 0, 'p', 200]), ({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'q', 'width': 300, 'sibling_width': 200, 'gutter': 8}, [True, False, 'q', 8, 'q', 508]), ({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 0, 'sibling_width': 200, 'gutter': 8}, [True, False, 'q', 8, 'q', 208]), ({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 300, 'sibling_width': 200, 'gutter': 0}, [True, False, 'q', 0, 'q', 500]), ({'remaining': 1, 'root': True, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 300, 'sibling_width': 200, 'gutter': 8}, [False, False, 'p', 0, 'p', 200])], 2: [({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 600, 'sibling_width': 400, 'gutter': 16}, [True, False, 'q', 16, 'q', 1016]), ({'remaining': 1, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 600, 'sibling_width': 400, 'gutter': 16}, [False, False, 'p', 0, 'p', 400]), ({'remaining': 0, 'root': True, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 600, 'sibling_width': 400, 'gutter': 16}, [False, True, 'p', 0, 'p', 400]), ({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'q', 'width': 600, 'sibling_width': 400, 'gutter': 16}, [True, False, 'q', 16, 'q', 1016]), ({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 0, 'sibling_width': 400, 'gutter': 16}, [True, False, 'q', 16, 'q', 416]), ({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 600, 'sibling_width': 400, 'gutter': 0}, [True, False, 'q', 0, 'q', 1000]), ({'remaining': 1, 'root': True, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 600, 'sibling_width': 400, 'gutter': 16}, [False, False, 'p', 0, 'p', 400])], 3: [({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 900, 'sibling_width': 600, 'gutter': 24}, [True, False, 'q', 24, 'q', 1524]), ({'remaining': 1, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 900, 'sibling_width': 600, 'gutter': 24}, [False, False, 'p', 0, 'p', 600]), ({'remaining': 0, 'root': True, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 900, 'sibling_width': 600, 'gutter': 24}, [False, True, 'p', 0, 'p', 600]), ({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'q', 'width': 900, 'sibling_width': 600, 'gutter': 24}, [True, False, 'q', 24, 'q', 1524]), ({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 0, 'sibling_width': 600, 'gutter': 24}, [True, False, 'q', 24, 'q', 624]), ({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 900, 'sibling_width': 600, 'gutter': 0}, [True, False, 'q', 0, 'q', 1500]), ({'remaining': 1, 'root': True, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 900, 'sibling_width': 600, 'gutter': 24}, [False, False, 'p', 0, 'p', 600])], 4: [({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 1200, 'sibling_width': 800, 'gutter': 32}, [True, False, 'q', 32, 'q', 2032]), ({'remaining': 1, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 1200, 'sibling_width': 800, 'gutter': 32}, [False, False, 'p', 0, 'p', 800]), ({'remaining': 0, 'root': True, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 1200, 'sibling_width': 800, 'gutter': 32}, [False, True, 'p', 0, 'p', 800]), ({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'q', 'width': 1200, 'sibling_width': 800, 'gutter': 32}, [True, False, 'q', 32, 'q', 2032]), ({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 0, 'sibling_width': 800, 'gutter': 32}, [True, False, 'q', 32, 'q', 832]), ({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 1200, 'sibling_width': 800, 'gutter': 0}, [True, False, 'q', 0, 'q', 2000]), ({'remaining': 1, 'root': True, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 1200, 'sibling_width': 800, 'gutter': 32}, [False, False, 'p', 0, 'p', 800])], 5: [({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 1500, 'sibling_width': 1000, 'gutter': 40}, [True, False, 'q', 40, 'q', 2540]), ({'remaining': 1, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 1500, 'sibling_width': 1000, 'gutter': 40}, [False, False, 'p', 0, 'p', 1000]), ({'remaining': 0, 'root': True, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 1500, 'sibling_width': 1000, 'gutter': 40}, [False, True, 'p', 0, 'p', 1000]), ({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'q', 'width': 1500, 'sibling_width': 1000, 'gutter': 40}, [True, False, 'q', 40, 'q', 2540]), ({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 0, 'sibling_width': 1000, 'gutter': 40}, [True, False, 'q', 40, 'q', 1040]), ({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 1500, 'sibling_width': 1000, 'gutter': 0}, [True, False, 'q', 0, 'q', 2500]), ({'remaining': 1, 'root': True, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 1500, 'sibling_width': 1000, 'gutter': 40}, [False, False, 'p', 0, 'p', 1000])]}
for i, (inputs, expected) in enumerate(fixtures[N]):
    check("workspace regression "+str(i), solve(inputs), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
Boundary fixtureActualExpectedOutcome
workspace regression 0[True, False, 'q', 8, 'q', 508][True, False, 'q', 8, 'q', 508]Passed
workspace regression 1[False, False, 'p', 0, 'p', 200][False, False, 'p', 0, 'p', 200]Passed
workspace regression 2[True, True, 'p', 0, 'p', 200][False, True, 'p', 0, 'p', 200]Failed
workspace regression 3[True, False, 'q', 8, 'q', 508][True, False, 'q', 8, 'q', 508]Passed
workspace regression 4[True, False, 'q', 8, 'q', 208][True, False, 'q', 8, 'q', 208]Passed
workspace regression 5[True, False, 'q', 0, 'q', 500][True, False, 'q', 0, 'q', 500]Passed
workspace regression 6[False, False, 'p', 0, 'p', 200][False, False, 'p', 0, 'p', 200]Passed

SHA-256 / 56f47dc2a280f4ec59e4eea05da78392967d22d97329c7fd73744d7a3d2d01c0

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x):
    r0 = not x['root']
    r1 = x['remaining']==0 and x['root']
    r2 = x['sibling'] if x['remaining']==0 and not x['root'] else x['pane']
    r3 = x['gutter'] if x['remaining']==0 and not x['root'] else 0
    r4 = x['sibling'] if x['remaining']==0 and not x['root'] and x['active']==x['pane'] else x['active']
    r5 = x['width']+x['sibling_width']+x['gutter'] if x['remaining']==0 and not x['root'] else x['sibling_width']
    return [r0,r1,r2,r3,r4,r5]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = {1: [({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 300, 'sibling_width': 200, 'gutter': 8}, [True, False, 'q', 8, 'q', 508]), ({'remaining': 1, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 300, 'sibling_width': 200, 'gutter': 8}, [False, False, 'p', 0, 'p', 200]), ({'remaining': 0, 'root': True, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 300, 'sibling_width': 200, 'gutter': 8}, [False, True, 'p', 0, 'p', 200]), ({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'q', 'width': 300, 'sibling_width': 200, 'gutter': 8}, [True, False, 'q', 8, 'q', 508]), ({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 0, 'sibling_width': 200, 'gutter': 8}, [True, False, 'q', 8, 'q', 208]), ({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 300, 'sibling_width': 200, 'gutter': 0}, [True, False, 'q', 0, 'q', 500]), ({'remaining': 1, 'root': True, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 300, 'sibling_width': 200, 'gutter': 8}, [False, False, 'p', 0, 'p', 200])], 2: [({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 600, 'sibling_width': 400, 'gutter': 16}, [True, False, 'q', 16, 'q', 1016]), ({'remaining': 1, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 600, 'sibling_width': 400, 'gutter': 16}, [False, False, 'p', 0, 'p', 400]), ({'remaining': 0, 'root': True, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 600, 'sibling_width': 400, 'gutter': 16}, [False, True, 'p', 0, 'p', 400]), ({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'q', 'width': 600, 'sibling_width': 400, 'gutter': 16}, [True, False, 'q', 16, 'q', 1016]), ({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 0, 'sibling_width': 400, 'gutter': 16}, [True, False, 'q', 16, 'q', 416]), ({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 600, 'sibling_width': 400, 'gutter': 0}, [True, False, 'q', 0, 'q', 1000]), ({'remaining': 1, 'root': True, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 600, 'sibling_width': 400, 'gutter': 16}, [False, False, 'p', 0, 'p', 400])], 3: [({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 900, 'sibling_width': 600, 'gutter': 24}, [True, False, 'q', 24, 'q', 1524]), ({'remaining': 1, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 900, 'sibling_width': 600, 'gutter': 24}, [False, False, 'p', 0, 'p', 600]), ({'remaining': 0, 'root': True, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 900, 'sibling_width': 600, 'gutter': 24}, [False, True, 'p', 0, 'p', 600]), ({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'q', 'width': 900, 'sibling_width': 600, 'gutter': 24}, [True, False, 'q', 24, 'q', 1524]), ({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 0, 'sibling_width': 600, 'gutter': 24}, [True, False, 'q', 24, 'q', 624]), ({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 900, 'sibling_width': 600, 'gutter': 0}, [True, False, 'q', 0, 'q', 1500]), ({'remaining': 1, 'root': True, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 900, 'sibling_width': 600, 'gutter': 24}, [False, False, 'p', 0, 'p', 600])], 4: [({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 1200, 'sibling_width': 800, 'gutter': 32}, [True, False, 'q', 32, 'q', 2032]), ({'remaining': 1, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 1200, 'sibling_width': 800, 'gutter': 32}, [False, False, 'p', 0, 'p', 800]), ({'remaining': 0, 'root': True, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 1200, 'sibling_width': 800, 'gutter': 32}, [False, True, 'p', 0, 'p', 800]), ({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'q', 'width': 1200, 'sibling_width': 800, 'gutter': 32}, [True, False, 'q', 32, 'q', 2032]), ({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 0, 'sibling_width': 800, 'gutter': 32}, [True, False, 'q', 32, 'q', 832]), ({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 1200, 'sibling_width': 800, 'gutter': 0}, [True, False, 'q', 0, 'q', 2000]), ({'remaining': 1, 'root': True, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 1200, 'sibling_width': 800, 'gutter': 32}, [False, False, 'p', 0, 'p', 800])], 5: [({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 1500, 'sibling_width': 1000, 'gutter': 40}, [True, False, 'q', 40, 'q', 2540]), ({'remaining': 1, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 1500, 'sibling_width': 1000, 'gutter': 40}, [False, False, 'p', 0, 'p', 1000]), ({'remaining': 0, 'root': True, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 1500, 'sibling_width': 1000, 'gutter': 40}, [False, True, 'p', 0, 'p', 1000]), ({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'q', 'width': 1500, 'sibling_width': 1000, 'gutter': 40}, [True, False, 'q', 40, 'q', 2540]), ({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 0, 'sibling_width': 1000, 'gutter': 40}, [True, False, 'q', 40, 'q', 1040]), ({'remaining': 0, 'root': False, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 1500, 'sibling_width': 1000, 'gutter': 0}, [True, False, 'q', 0, 'q', 2500]), ({'remaining': 1, 'root': True, 'sibling': 'q', 'pane': 'p', 'active': 'p', 'width': 1500, 'sibling_width': 1000, 'gutter': 40}, [False, False, 'p', 0, 'p', 1000])]}
for i, (inputs, expected) in enumerate(fixtures[N]):
    check("workspace regression "+str(i), solve(inputs), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
Boundary fixtureActualExpectedOutcome
workspace regression 0[True, False, 'q', 8, 'q', 508][True, False, 'q', 8, 'q', 508]Passed
workspace regression 1[True, False, 'p', 0, 'p', 200][False, False, 'p', 0, 'p', 200]Failed
workspace regression 2[False, True, 'p', 0, 'p', 200][False, True, 'p', 0, 'p', 200]Passed
workspace regression 3[True, False, 'q', 8, 'q', 508][True, False, 'q', 8, 'q', 508]Passed
workspace regression 4[True, False, 'q', 8, 'q', 208][True, False, 'q', 8, 'q', 208]Passed
workspace regression 5[True, False, 'q', 0, 'q', 500][True, False, 'q', 0, 'q', 500]Passed
workspace regression 6[False, False, 'p', 0, 'p', 200][False, False, 'p', 0, 'p', 200]Passed

SHA-256 / a23d21f9d2d2cdb51bb7279a0232aed8b8faab37d6b210498c65b989e4bb3b93

HELD IN THE MEMBER ARCHIVE

The verified repair and its recorded checks are member-only.

This mechanism has 7 recorded checks per implementation. The open-access tier publishes the failure and the unsuccessful fix; the repaired source that passes every check, and the observations that prove it, are available to members.

Every case sharing this mechanism uses the same contract and the same repair, so this one record is held back for all of them.

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Verification & scope

Finite stipulated workspace snapshots only. Independent result fields describe observable obligations, not a full UI runtime. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.

Observations recorded using Python 3.12.14 at 2026-09-29T14:42:46.082694+00:00.

Case digest / 424390c8ca311ba78e5d88fa6d8401c91ac20049c8ad3748325cd97e8e80d0d7