FA-11796 / Document structure integrity / Open access

An explicitly empty section header incorrectly inherits content · case 01

An explicitly empty section header incorrectly inherits content in the controlled document model.

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

ROOT CAUSE

Every missing header is replaced with the global default instead of the previous section header.

VERIFIED REPAIR

Resolve only None through the preceding section and retain explicit empty content.

Unsuccessful approach: A truthiness fallback conflates an explicitly blank header with a linked header.

Case contract

Each section header is a string or None; None links to the previous resolved header, initially default, while empty string explicitly clears it.

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(headers):
    return [x or 'default' for x in headers]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [((['H'+str(N),None,'',None],),['H'+str(N),'H'+str(N),'','']), (([],),[]), (([None],),['default']), (([''],),['']), ((['a',None],),['a','a']), ((['a','b',None],),['a','b','b'])]
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	`['H1', 'default', 'default', 'default']`	`['H1', 'H1', '', '']`	Failed
document fixture 1	`[]`	`[]`	Passed
document fixture 2	`['default']`	`['default']`	Passed
document fixture 3	`['default']`	`['']`	Failed
document fixture 4	`['a', 'default']`	`['a', 'a']`	Failed
document fixture 5	`['a', 'b', 'default']`	`['a', 'b', 'b']`	Failed

SHA-256 / fde00e64850167971739f47e84c0d43cd5ad39b1bc7e5c44febdc9e6bbc22f40

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(headers):
    out=[]
    last='default'
    for x in headers:
        last=x or last
        out.append(last)
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [((['H'+str(N),None,'',None],),['H'+str(N),'H'+str(N),'','']), (([],),[]), (([None],),['default']), (([''],),['']), ((['a',None],),['a','a']), ((['a','b',None],),['a','b','b'])]
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	`['H1', 'H1', 'H1', 'H1']`	`['H1', 'H1', '', '']`	Failed
document fixture 1	`[]`	`[]`	Passed
document fixture 2	`['default']`	`['default']`	Passed
document fixture 3	`['default']`	`['']`	Failed
document fixture 4	`['a', 'a']`	`['a', 'a']`	Passed
document fixture 5	`['a', 'b', 'b']`	`['a', 'b', 'b']`	Passed

SHA-256 / dc1028079c178deb645b825ad177e3feb9cd90f9ba5f5ba17a6c7137001533b1

3 / The verified repair

Exit 0

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

N = 1
observations = []
def solve(headers):
    out=[]
    last='default'
    for x in headers:
        if x is not None: last=x
        out.append(last)
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [((['H'+str(N),None,'',None],),['H'+str(N),'H'+str(N),'','']), (([],),[]), (([None],),['default']), (([''],),['']), ((['a',None],),['a','a']), ((['a','b',None],),['a','b','b'])]
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	`['H1', 'H1', '', '']`	`['H1', 'H1', '', '']`	Passed
document fixture 1	`[]`	`[]`	Passed
document fixture 2	`['default']`	`['default']`	Passed
document fixture 3	`['']`	`['']`	Passed
document fixture 4	`['a', 'a']`	`['a', 'a']`	Passed
document fixture 5	`['a', 'b', 'b']`	`['a', 'b', 'b']`	Passed

SHA-256 / 86d4f857315ec827a9c1eb23c216454f00d048aecd7a8cc0e6489d887f7537b9

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 2026-09-29T14:38:51.092583+00:00.

Case digest / 28caf3b650b1f481ffca7354557f46c07424c603dfd433c2967ff5a0aad8df7b