FA-11806 / Document structure integrity / Open access

A heading attaches to a previous sibling instead of a shallower heading · case 01

A heading attaches to a previous sibling instead of a shallower heading in the controlled document model.

Verified by executionVariant 1 · 6 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

An outline builder treats the immediately previous heading as the parent.

THE FAILURE

An outline builder treats the immediately previous heading as the parent.

Unsuccessful approach: Requiring an exact preceding level drops a legal parent when the outline skips a level.

Case contract

For each positive heading level, return the index of the nearest preceding heading with a strictly smaller level, or None.

Why this case matters

Structured editing must preserve document semantics independently of visual rendering.

1 / The failure

Exit 1

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

N = 1
observations = []
def solve(levels):
    return [None]+list(range(len(levels)-1)) if levels else []
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [(([1,3,3,2+N],),[None,0,0,0 if N==1 else 2]), (([],),[]), (([2],),[None]), (([1,1],),[None,None]), (([1,4],),[None,0]), (([2,4,1,3],),[None,0,None,2])]
for i, (args, expected) in enumerate(fixtures):
    check("document fixture " + str(i), solve(*args), 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
document fixture 0	`[None, 0, 1, 2]`	`[None, 0, 0, 0]`	Failed
document fixture 1	`[]`	`[]`	Passed
document fixture 2	`[None]`	`[None]`	Passed
document fixture 3	`[None, 0]`	`[None, None]`	Failed
document fixture 4	`[None, 0]`	`[None, 0]`	Passed
document fixture 5	`[None, 0, 1, 2]`	`[None, 0, None, 2]`	Failed

SHA-256 / 9f5df43765a8c7bb91c84c66443d8ff2f4374cb1f9fa9638df4b7ed3dff67636

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(levels):
    return [next((j for j in range(i-1,-1,-1) if levels[j]==level-1),None) for i,level in enumerate(levels)]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [(([1,3,3,2+N],),[None,0,0,0 if N==1 else 2]), (([],),[]), (([2],),[None]), (([1,1],),[None,None]), (([1,4],),[None,0]), (([2,4,1,3],),[None,0,None,2])]
for i, (args, expected) in enumerate(fixtures):
    check("document fixture " + str(i), solve(*args), 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
document fixture 0	`[None, None, None, None]`	`[None, 0, 0, 0]`	Failed
document fixture 1	`[]`	`[]`	Passed
document fixture 2	`[None]`	`[None]`	Passed
document fixture 3	`[None, None]`	`[None, None]`	Passed
document fixture 4	`[None, None]`	`[None, 0]`	Failed
document fixture 5	`[None, None, None, 0]`	`[None, 0, None, 2]`	Failed

SHA-256 / 17439a3a563e2534a082c937862f02412b38f0b4498a7b877a3669389d3285b3

HELD IN THE MEMBER ARCHIVE

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

This mechanism has 6 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.

Member access is invitation-based. Sign in with your invited account to inspect the repair.

Verification & scope

An offline simplified document model, not a claim of conformance to any office file format. 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 2026-09-29T14:38:51.134527+00:00.

Case digest / c95943cb085e0e985dfd9cb1e58b36e9a0dbb6da76a5acf2c781c426a560044e