FA-99676 / Chunk citation alignment / Open access

A citation anchor is assigned to every overlapping chunk · case 01

A citation anchor is assigned to every overlapping chunk.

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

ROOT CAUSE

Overlap duplicates the same source anchor in stitched output.

THE FAILURE

Overlap duplicates the same source anchor in stitched output.

Unsuccessful approach: Keeping only chunks that contain the entire span drops valid citations split across chunk boundaries.

Case contract

Given chunks [start,end] and citation [s,e), return indices of chunks containing s, selecting the earliest only; chunk containment is start <= s < end.

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(chunks, span):
    s,e=span
    return [i for i,(a,b) in enumerate(chunks) if a<e and s<b]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('overlap earliest',solve([[0,5],[3,8]],[4,7]),[0])
check('anchor second',solve([[0,2],[2,5]],[2,4]),[1])
check('at end excluded',solve([[0,2]],[2,3]),[])
check('empty chunks',solve([],[0,1]),[])
check('anchor despite tail crossing',solve([[0,3],[3,6]],[2,5]),[0])
check('no containing start',solve([[0,2]],[4,5]),[])
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
overlap earliest	`[0, 1]`	`[0]`	Failed
anchor second	`[1]`	`[1]`	Passed
at end excluded	`[]`	`[]`	Passed
empty chunks	`[]`	`[]`	Passed
anchor despite tail crossing	`[0, 1]`	`[0]`	Failed
no containing start	`[]`	`[]`	Passed

SHA-256 / 36d9c9083c5fb0ff37b13b338daa2f57b2400fb08d99770d661688bf76a55d54

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(chunks, span):
    s,e=span
    return [i for i,(a,b) in enumerate(chunks) if a<=s and e<=b][:1]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('overlap earliest',solve([[0,5],[3,8]],[4,7]),[0])
check('anchor second',solve([[0,2],[2,5]],[2,4]),[1])
check('at end excluded',solve([[0,2]],[2,3]),[])
check('empty chunks',solve([],[0,1]),[])
check('anchor despite tail crossing',solve([[0,3],[3,6]],[2,5]),[0])
check('no containing start',solve([[0,2]],[4,5]),[])
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
overlap earliest	`[1]`	`[0]`	Failed
anchor second	`[1]`	`[1]`	Passed
at end excluded	`[]`	`[]`	Passed
empty chunks	`[]`	`[]`	Passed
anchor despite tail crossing	`[]`	`[0]`	Failed
no containing start	`[]`	`[]`	Passed

SHA-256 / 18ebcdd93a7af0dcac78ec86ab1108f7869405ed0d2af5a850476c0ddf7897de

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

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 2026-09-30T16:48:26.742010+00:00.

Case digest / 3786b9810824273e63e3cf5ac90c0b24901da9d1043fa39f4f9809ab2ec76862