FA-38571 / Tree accessibility / Open access

Persisted hierarchical expansion restoration: Visibility ignores outer collapsed ancestry · case 01

Visibility ignores outer collapsed ancestry produces the wrong hierarchical widget state in a regression fixture.

Verified by executionVariant 1 · 8 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The expansion-restore contract is violated at `all(a in expanded for a in d['ancestors'].get(x,[]))` by replacing it with `any(a in expanded for a in d['ancestors'].get(x,[]))`.

VERIFIED REPAIR

Restore `all(a in expanded for a in d['ancestors'].get(x,[]))` at this fault site while retaining the other tree state decisions.

Unsuccessful approach: The partial repair `not d['ancestors'].get(x) or d['ancestors'][x][-1] in expanded` still violates a boundary or preservation case.

Case contract

Only present branch IDs may be restored. Ancestors of restored open branches are opened unless explicitly blocked. Selection and focus restore independently: selection keeps present enabled rows; hidden focus falls back to nearest visible ancestor. The persisted root instance must match.

Why this case matters

Offline executable model of a hierarchical accessibility interaction; inputs are bounded and valid as stipulated. No browser, assistive technology, or normative ARIA conformance is claimed.

1 / The failure

Exit 1

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

N = 1
observations = []
def solve(d):
    valid=d['saved_tree']==d['tree']
    wanted=set(d['saved_open']) if valid else set()
    branches=wanted & set(d['branches'])
    ancestors={a for x in branches for a in d['ancestors'].get(x,[])}
    expanded=(branches|ancestors)-set(d['blocked'])
    selected=[x for x in d['saved_selected'] if valid and x in d['present'] and x not in d['disabled']]
    visible=[x for x in d['present'] if any(a in expanded for a in d['ancestors'].get(x,[]))]
    candidate=d['saved_focus'] if valid else None
    fallback=next((a for a in reversed(d['ancestors'].get(candidate,[])) if a in visible),None)
    focus=candidate if candidate in visible else (fallback if fallback is not None else (visible[0] if visible else None))
    return [sorted(expanded),selected,visible,focus]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = {1: [('deep saved', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']), ('deep branch alone', {'saved_tree': 't', 'tree': 't', 'saved_open': ['b'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']), ('foreign snapshot', {'saved_tree': 'other', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'other'}, [[], [], ['r', 'other'], 'r']), ('blocked middle', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': ['b'], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'r'], ['leaf'], ['r', 'a', 'b', 'other'], 'b']), ('blocked root', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': ['r'], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b'], ['leaf'], ['r', 'other'], 'r']), ('no saved branch', {'saved_tree': 't', 'tree': 't', 'saved_open': [], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [[], ['leaf'], ['r', 'other'], 'r']), ('missing focus', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'gone'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'r']), ('deep varying chain', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf'], 'present': ['r', 'a', 'b', 'leaf', 'other', 'v0'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other', 'v0'], 'leaf'])], 2: [('deep saved', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']), ('deep branch alone', {'saved_tree': 't', 'tree': 't', 'saved_open': ['b'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']), ('foreign snapshot', {'saved_tree': 'other', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'other'}, [[], [], ['r', 'other'], 'r']), ('blocked middle', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': ['b'], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'r'], ['leaf'], ['r', 'a', 'b', 'other'], 'b']), ('blocked root', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': ['r'], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b'], ['leaf'], ['r', 'other'], 'r']), ('no saved branch', {'saved_tree': 't', 'tree': 't', 'saved_open': [], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [[], ['leaf'], ['r', 'other'], 'r']), ('missing focus', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'gone'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'r']), ('deep varying chain', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf'], 'present': ['r', 'a', 'b', 'leaf', 'other', 'v0', 'v1'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other', 'v0', 'v1'], 'leaf'])], 3: [('deep saved', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']), ('deep branch alone', {'saved_tree': 't', 'tree': 't', 'saved_open': ['b'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']), ('foreign snapshot', {'saved_tree': 'other', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'other'}, [[], [], ['r', 'other'], 'r']), ('blocked middle', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': ['b'], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'r'], ['leaf'], ['r', 'a', 'b', 'other'], 'b']), ('blocked root', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': ['r'], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b'], ['leaf'], ['r', 'other'], 'r']), ('no saved branch', {'saved_tree': 't', 'tree': 't', 'saved_open': [], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [[], ['leaf'], ['r', 'other'], 'r']), ('missing focus', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'gone'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'r']), ('deep varying chain', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf'], 'present': ['r', 'a', 'b', 'leaf', 'other', 'v0', 'v1', 'v2'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other', 'v0', 'v1', 'v2'], 'leaf'])], 4: [('deep saved', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']), ('deep branch alone', {'saved_tree': 't', 'tree': 't', 'saved_open': ['b'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']), ('foreign snapshot', {'saved_tree': 'other', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'other'}, [[], [], ['r', 'other'], 'r']), ('blocked middle', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': ['b'], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'r'], ['leaf'], ['r', 'a', 'b', 'other'], 'b']), ('blocked root', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': ['r'], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b'], ['leaf'], ['r', 'other'], 'r']), ('no saved branch', {'saved_tree': 't', 'tree': 't', 'saved_open': [], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [[], ['leaf'], ['r', 'other'], 'r']), ('missing focus', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'gone'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'r']), ('deep varying chain', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf'], 'present': ['r', 'a', 'b', 'leaf', 'other', 'v0', 'v1', 'v2', 'v3'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other', 'v0', 'v1', 'v2', 'v3'], 'leaf'])], 5: [('deep saved', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']), ('deep branch alone', {'saved_tree': 't', 'tree': 't', 'saved_open': ['b'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']), ('foreign snapshot', {'saved_tree': 'other', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'other'}, [[], [], ['r', 'other'], 'r']), ('blocked middle', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': ['b'], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'r'], ['leaf'], ['r', 'a', 'b', 'other'], 'b']), ('blocked root', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': ['r'], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b'], ['leaf'], ['r', 'other'], 'r']), ('no saved branch', {'saved_tree': 't', 'tree': 't', 'saved_open': [], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [[], ['leaf'], ['r', 'other'], 'r']), ('missing focus', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'gone'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'r']), ('deep varying chain', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf'], 'present': ['r', 'a', 'b', 'leaf', 'other', 'v0', 'v1', 'v2', 'v3', 'v4'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other', 'v0', 'v1', 'v2', 'v3', 'v4'], 'leaf'])]}
for label, data, expected in cases[N]:
    check(label, solve(data), 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 fixture	Actual	Expected	Outcome
deep saved	`[['a', 'b', 'r'], ['leaf'], ['a', 'b', 'leaf'], 'leaf']`	`[['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']`	Failed
deep branch alone	`[['a', 'b', 'r'], ['leaf'], ['a', 'b', 'leaf'], 'leaf']`	`[['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']`	Failed
foreign snapshot	`[[], [], [], None]`	`[[], [], ['r', 'other'], 'r']`	Failed
blocked middle	`[['a', 'r'], ['leaf'], ['a', 'b', 'leaf'], 'leaf']`	`[['a', 'r'], ['leaf'], ['r', 'a', 'b', 'other'], 'b']`	Failed
blocked root	`[['a', 'b'], ['leaf'], ['b', 'leaf'], 'leaf']`	`[['a', 'b'], ['leaf'], ['r', 'other'], 'r']`	Failed
no saved branch	`[[], ['leaf'], [], None]`	`[[], ['leaf'], ['r', 'other'], 'r']`	Failed
missing focus	`[['a', 'b', 'r'], ['leaf'], ['a', 'b', 'leaf'], 'a']`	`[['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'r']`	Failed
deep varying chain	`[['a', 'b', 'r'], ['leaf'], ['a', 'b', 'leaf'], 'leaf']`	`[['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other', 'v0'], 'leaf']`	Failed

SHA-256 / 5d9d5e8e047ae7d28a1799eff59396b92db7b5219ee3b80046cd3cbb0e4aa23d

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(d):
    valid=d['saved_tree']==d['tree']
    wanted=set(d['saved_open']) if valid else set()
    branches=wanted & set(d['branches'])
    ancestors={a for x in branches for a in d['ancestors'].get(x,[])}
    expanded=(branches|ancestors)-set(d['blocked'])
    selected=[x for x in d['saved_selected'] if valid and x in d['present'] and x not in d['disabled']]
    visible=[x for x in d['present'] if not d['ancestors'].get(x) or d['ancestors'][x][-1] in expanded]
    candidate=d['saved_focus'] if valid else None
    fallback=next((a for a in reversed(d['ancestors'].get(candidate,[])) if a in visible),None)
    focus=candidate if candidate in visible else (fallback if fallback is not None else (visible[0] if visible else None))
    return [sorted(expanded),selected,visible,focus]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = {1: [('deep saved', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']), ('deep branch alone', {'saved_tree': 't', 'tree': 't', 'saved_open': ['b'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']), ('foreign snapshot', {'saved_tree': 'other', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'other'}, [[], [], ['r', 'other'], 'r']), ('blocked middle', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': ['b'], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'r'], ['leaf'], ['r', 'a', 'b', 'other'], 'b']), ('blocked root', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': ['r'], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b'], ['leaf'], ['r', 'other'], 'r']), ('no saved branch', {'saved_tree': 't', 'tree': 't', 'saved_open': [], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [[], ['leaf'], ['r', 'other'], 'r']), ('missing focus', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'gone'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'r']), ('deep varying chain', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf'], 'present': ['r', 'a', 'b', 'leaf', 'other', 'v0'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other', 'v0'], 'leaf'])], 2: [('deep saved', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']), ('deep branch alone', {'saved_tree': 't', 'tree': 't', 'saved_open': ['b'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']), ('foreign snapshot', {'saved_tree': 'other', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'other'}, [[], [], ['r', 'other'], 'r']), ('blocked middle', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': ['b'], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'r'], ['leaf'], ['r', 'a', 'b', 'other'], 'b']), ('blocked root', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': ['r'], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b'], ['leaf'], ['r', 'other'], 'r']), ('no saved branch', {'saved_tree': 't', 'tree': 't', 'saved_open': [], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [[], ['leaf'], ['r', 'other'], 'r']), ('missing focus', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'gone'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'r']), ('deep varying chain', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf'], 'present': ['r', 'a', 'b', 'leaf', 'other', 'v0', 'v1'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other', 'v0', 'v1'], 'leaf'])], 3: [('deep saved', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']), ('deep branch alone', {'saved_tree': 't', 'tree': 't', 'saved_open': ['b'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']), ('foreign snapshot', {'saved_tree': 'other', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'other'}, [[], [], ['r', 'other'], 'r']), ('blocked middle', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': ['b'], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'r'], ['leaf'], ['r', 'a', 'b', 'other'], 'b']), ('blocked root', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': ['r'], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b'], ['leaf'], ['r', 'other'], 'r']), ('no saved branch', {'saved_tree': 't', 'tree': 't', 'saved_open': [], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [[], ['leaf'], ['r', 'other'], 'r']), ('missing focus', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'gone'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'r']), ('deep varying chain', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf'], 'present': ['r', 'a', 'b', 'leaf', 'other', 'v0', 'v1', 'v2'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other', 'v0', 'v1', 'v2'], 'leaf'])], 4: [('deep saved', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']), ('deep branch alone', {'saved_tree': 't', 'tree': 't', 'saved_open': ['b'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']), ('foreign snapshot', {'saved_tree': 'other', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'other'}, [[], [], ['r', 'other'], 'r']), ('blocked middle', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': ['b'], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'r'], ['leaf'], ['r', 'a', 'b', 'other'], 'b']), ('blocked root', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': ['r'], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b'], ['leaf'], ['r', 'other'], 'r']), ('no saved branch', {'saved_tree': 't', 'tree': 't', 'saved_open': [], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [[], ['leaf'], ['r', 'other'], 'r']), ('missing focus', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'gone'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'r']), ('deep varying chain', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf'], 'present': ['r', 'a', 'b', 'leaf', 'other', 'v0', 'v1', 'v2', 'v3'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other', 'v0', 'v1', 'v2', 'v3'], 'leaf'])], 5: [('deep saved', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']), ('deep branch alone', {'saved_tree': 't', 'tree': 't', 'saved_open': ['b'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']), ('foreign snapshot', {'saved_tree': 'other', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'other'}, [[], [], ['r', 'other'], 'r']), ('blocked middle', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': ['b'], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'r'], ['leaf'], ['r', 'a', 'b', 'other'], 'b']), ('blocked root', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': ['r'], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b'], ['leaf'], ['r', 'other'], 'r']), ('no saved branch', {'saved_tree': 't', 'tree': 't', 'saved_open': [], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [[], ['leaf'], ['r', 'other'], 'r']), ('missing focus', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'gone'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'r']), ('deep varying chain', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf'], 'present': ['r', 'a', 'b', 'leaf', 'other', 'v0', 'v1', 'v2', 'v3', 'v4'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other', 'v0', 'v1', 'v2', 'v3', 'v4'], 'leaf'])]}
for label, data, expected in cases[N]:
    check(label, solve(data), 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 fixture	Actual	Expected	Outcome
deep saved	`[['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']`	`[['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']`	Passed
deep branch alone	`[['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']`	`[['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']`	Passed
foreign snapshot	`[[], [], ['r', 'other'], 'r']`	`[[], [], ['r', 'other'], 'r']`	Passed
blocked middle	`[['a', 'r'], ['leaf'], ['r', 'a', 'b', 'other'], 'b']`	`[['a', 'r'], ['leaf'], ['r', 'a', 'b', 'other'], 'b']`	Passed
blocked root	`[['a', 'b'], ['leaf'], ['r', 'b', 'leaf', 'other'], 'leaf']`	`[['a', 'b'], ['leaf'], ['r', 'other'], 'r']`	Failed
no saved branch	`[[], ['leaf'], ['r', 'other'], 'r']`	`[[], ['leaf'], ['r', 'other'], 'r']`	Passed
missing focus	`[['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'r']`	`[['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'r']`	Passed
deep varying chain	`[['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other', 'v0'], 'leaf']`	`[['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other', 'v0'], 'leaf']`	Passed

SHA-256 / 85efd7ece52154a110e70ab0e5b5041674db3c1e76af548297a981572ca17d5f

3 / The verified repair

Exit 0

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

N = 1
observations = []
def solve(d):
    valid=d['saved_tree']==d['tree']
    wanted=set(d['saved_open']) if valid else set()
    branches=wanted & set(d['branches'])
    ancestors={a for x in branches for a in d['ancestors'].get(x,[])}
    expanded=(branches|ancestors)-set(d['blocked'])
    selected=[x for x in d['saved_selected'] if valid and x in d['present'] and x not in d['disabled']]
    visible=[x for x in d['present'] if all(a in expanded for a in d['ancestors'].get(x,[]))]
    candidate=d['saved_focus'] if valid else None
    fallback=next((a for a in reversed(d['ancestors'].get(candidate,[])) if a in visible),None)
    focus=candidate if candidate in visible else (fallback if fallback is not None else (visible[0] if visible else None))
    return [sorted(expanded),selected,visible,focus]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = {1: [('deep saved', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']), ('deep branch alone', {'saved_tree': 't', 'tree': 't', 'saved_open': ['b'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']), ('foreign snapshot', {'saved_tree': 'other', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'other'}, [[], [], ['r', 'other'], 'r']), ('blocked middle', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': ['b'], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'r'], ['leaf'], ['r', 'a', 'b', 'other'], 'b']), ('blocked root', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': ['r'], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b'], ['leaf'], ['r', 'other'], 'r']), ('no saved branch', {'saved_tree': 't', 'tree': 't', 'saved_open': [], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [[], ['leaf'], ['r', 'other'], 'r']), ('missing focus', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'gone'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'r']), ('deep varying chain', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf'], 'present': ['r', 'a', 'b', 'leaf', 'other', 'v0'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other', 'v0'], 'leaf'])], 2: [('deep saved', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']), ('deep branch alone', {'saved_tree': 't', 'tree': 't', 'saved_open': ['b'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']), ('foreign snapshot', {'saved_tree': 'other', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'other'}, [[], [], ['r', 'other'], 'r']), ('blocked middle', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': ['b'], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'r'], ['leaf'], ['r', 'a', 'b', 'other'], 'b']), ('blocked root', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': ['r'], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b'], ['leaf'], ['r', 'other'], 'r']), ('no saved branch', {'saved_tree': 't', 'tree': 't', 'saved_open': [], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [[], ['leaf'], ['r', 'other'], 'r']), ('missing focus', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'gone'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'r']), ('deep varying chain', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf'], 'present': ['r', 'a', 'b', 'leaf', 'other', 'v0', 'v1'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other', 'v0', 'v1'], 'leaf'])], 3: [('deep saved', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']), ('deep branch alone', {'saved_tree': 't', 'tree': 't', 'saved_open': ['b'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']), ('foreign snapshot', {'saved_tree': 'other', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'other'}, [[], [], ['r', 'other'], 'r']), ('blocked middle', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': ['b'], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'r'], ['leaf'], ['r', 'a', 'b', 'other'], 'b']), ('blocked root', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': ['r'], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b'], ['leaf'], ['r', 'other'], 'r']), ('no saved branch', {'saved_tree': 't', 'tree': 't', 'saved_open': [], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [[], ['leaf'], ['r', 'other'], 'r']), ('missing focus', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'gone'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'r']), ('deep varying chain', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf'], 'present': ['r', 'a', 'b', 'leaf', 'other', 'v0', 'v1', 'v2'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other', 'v0', 'v1', 'v2'], 'leaf'])], 4: [('deep saved', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']), ('deep branch alone', {'saved_tree': 't', 'tree': 't', 'saved_open': ['b'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']), ('foreign snapshot', {'saved_tree': 'other', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'other'}, [[], [], ['r', 'other'], 'r']), ('blocked middle', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': ['b'], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'r'], ['leaf'], ['r', 'a', 'b', 'other'], 'b']), ('blocked root', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': ['r'], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b'], ['leaf'], ['r', 'other'], 'r']), ('no saved branch', {'saved_tree': 't', 'tree': 't', 'saved_open': [], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [[], ['leaf'], ['r', 'other'], 'r']), ('missing focus', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'gone'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'r']), ('deep varying chain', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf'], 'present': ['r', 'a', 'b', 'leaf', 'other', 'v0', 'v1', 'v2', 'v3'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other', 'v0', 'v1', 'v2', 'v3'], 'leaf'])], 5: [('deep saved', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']), ('deep branch alone', {'saved_tree': 't', 'tree': 't', 'saved_open': ['b'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']), ('foreign snapshot', {'saved_tree': 'other', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'other'}, [[], [], ['r', 'other'], 'r']), ('blocked middle', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': ['b'], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'r'], ['leaf'], ['r', 'a', 'b', 'other'], 'b']), ('blocked root', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': ['r'], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b'], ['leaf'], ['r', 'other'], 'r']), ('no saved branch', {'saved_tree': 't', 'tree': 't', 'saved_open': [], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [[], ['leaf'], ['r', 'other'], 'r']), ('missing focus', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf', 'gone', 'a'], 'present': ['r', 'a', 'b', 'leaf', 'other'], 'disabled': ['a'], 'saved_focus': 'gone'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'r']), ('deep varying chain', {'saved_tree': 't', 'tree': 't', 'saved_open': ['a', 'b', 'leaf', 'gone'], 'branches': ['r', 'a', 'b'], 'ancestors': {'r': [], 'a': ['r'], 'b': ['r', 'a'], 'leaf': ['r', 'a', 'b'], 'other': []}, 'blocked': [], 'saved_selected': ['leaf'], 'present': ['r', 'a', 'b', 'leaf', 'other', 'v0', 'v1', 'v2', 'v3', 'v4'], 'disabled': ['a'], 'saved_focus': 'leaf'}, [['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other', 'v0', 'v1', 'v2', 'v3', 'v4'], 'leaf'])]}
for label, data, expected in cases[N]:
    check(label, solve(data), 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 fixture	Actual	Expected	Outcome
deep saved	`[['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']`	`[['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']`	Passed
deep branch alone	`[['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']`	`[['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'leaf']`	Passed
foreign snapshot	`[[], [], ['r', 'other'], 'r']`	`[[], [], ['r', 'other'], 'r']`	Passed
blocked middle	`[['a', 'r'], ['leaf'], ['r', 'a', 'b', 'other'], 'b']`	`[['a', 'r'], ['leaf'], ['r', 'a', 'b', 'other'], 'b']`	Passed
blocked root	`[['a', 'b'], ['leaf'], ['r', 'other'], 'r']`	`[['a', 'b'], ['leaf'], ['r', 'other'], 'r']`	Passed
no saved branch	`[[], ['leaf'], ['r', 'other'], 'r']`	`[[], ['leaf'], ['r', 'other'], 'r']`	Passed
missing focus	`[['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'r']`	`[['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other'], 'r']`	Passed
deep varying chain	`[['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other', 'v0'], 'leaf']`	`[['a', 'b', 'r'], ['leaf'], ['r', 'a', 'b', 'leaf', 'other', 'v0'], 'leaf']`	Passed

SHA-256 / bc4505aa47e30ddeb3b16427c618a7a81e08add271343ca2484643471ae3d28d

Verification & scope

Synthetic deterministic hierarchical-widget data contract; not an implementation of a browser accessibility tree. 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 2026-09-29T14:43:12.548492+00:00.

Case digest / 7ae4e5d6932de3bec895d5a3e983fbd7bd499246aa4328d64daa33e89aa9e9c9