FA-99641 / Chunk citation alignment / Open access

Chunk-local offsets omit the chunk base · case 01

Chunk-local offsets omit the chunk base.

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

ROOT CAUSE

A local span is treated as a document offset.

THE FAILURE

A local span is treated as a document offset.

Unsuccessful approach: Adding the base only to the start leaves the end local.

Case contract

Given chunk start b and local half-open span [s,e), return global [b+s,b+e).

Why this case matters

A deterministic citation bookkeeping model isolates source attribution from rendering and retrieval.

1 / The failure

Exit 1

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

N = 1
observations = []
def solve(base, span):
    s,e=span
    return [s,e]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('offset',solve(N,[2,5]),[N+2,N+5])
check('zero local',solve(N,[0,1]),[N,N+1])
check('nonzero base',solve(7,[3,4]),[10,11])
check('empty span',solve(N,[2,2]),[N+2,N+2])
check('wide span',solve(2,[1,8]),[3,10])
check('base zero',solve(0,[4,6]),[4,6])
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
offset	`[2, 5]`	`[3, 6]`	Failed
zero local	`[0, 1]`	`[1, 2]`	Failed
nonzero base	`[3, 4]`	`[10, 11]`	Failed
empty span	`[2, 2]`	`[3, 3]`	Failed
wide span	`[1, 8]`	`[3, 10]`	Failed
base zero	`[4, 6]`	`[4, 6]`	Passed

SHA-256 / cef6adcba993d5835d10c535a2e9dfd91c2016c6134892c7406672cc02029f37

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(base, span):
    s,e=span
    return [base+s,e]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('offset',solve(N,[2,5]),[N+2,N+5])
check('zero local',solve(N,[0,1]),[N,N+1])
check('nonzero base',solve(7,[3,4]),[10,11])
check('empty span',solve(N,[2,2]),[N+2,N+2])
check('wide span',solve(2,[1,8]),[3,10])
check('base zero',solve(0,[4,6]),[4,6])
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
offset	`[3, 5]`	`[3, 6]`	Failed
zero local	`[1, 1]`	`[1, 2]`	Failed
nonzero base	`[10, 4]`	`[10, 11]`	Failed
empty span	`[3, 2]`	`[3, 3]`	Failed
wide span	`[3, 8]`	`[3, 10]`	Failed
base zero	`[4, 6]`	`[4, 6]`	Passed

SHA-256 / e9c353666c867d9fd2b68233483e7444c2a9b0cdfb607ad1e3760dc3c275a16b

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.

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Verification & scope

Inputs are small integer offsets and identifiers under the stated toy contract; this does not define a document format or production citation API. 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 2026-09-30T16:48:26.712558+00:00.

Case digest / c3884cbfe013a8247a5a9321ec7575c739563b23121ef1e6d5b7f3c4798a067a