{"abstract":"Overlapping chunk citations include the already stitched prefix.","category":"Chunk citation alignment","checks":7,"contract":"Chunks are source intervals [start,end] in ascending order, each next interval overlaps or touches the prior covered frontier; stitching retains the first chunk in full and discards duplicate prefixes. Citation [chunk_index,local_start,local_end] maps to the nonempty retained piece in output-local coordinates, or None if fully overlapped.","contract_signature":"chunks, citation","evaluation_group":"w3-cca-stitched_overlap","failed_approach":"Clipping away the duplicated prefix still leaves citation coordinates in document space instead of output-local space.","family":"w3-chunk-citation-alignment-stitched-overlap-provenance","id":"FA-99671","implementations":{"attempt":{"sha256":"1a12d9bcd2dc41b36fe16be094a5daacfef1ec7ff34ab5ee216e4dfacf1ddf79","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(chunks, citation):\n    if not chunks: return None\n    i,lo,hi=citation\n    a,b=chunks[i]\n    frontier=max((end for start,end in chunks[:i]),default=a)\n    left=max(a+lo,frontier)\n    right=a+hi\n    return [left,right] if left<right else None\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nchunks=[[N,N+5],[N+3,N+8]]\ncheck('citation straddles duplicated prefix',solve(chunks,[1,1,4]),[5,7])\ncheck('entire citation already stitched',solve(chunks,[1,0,2]),None)\ncheck('citation starts after overlap',solve(chunks,[1,2,5]),[5,8])\ncheck('first chunk unchanged',solve(chunks,[0,1,3]),[1,3])\ncheck('touching chunk boundary',solve([[N,N+2],[N+2,N+4]],[1,0,2]),[2,4])\ncheck('empty citation',solve(chunks,[1,2,2]),None)\ncheck('no chunks',solve([],[0,0,1]),None)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"broken":{"sha256":"abf21de34a2de3f527d506233a6bf2788f93ce0d4bef4b3d539782c772717716","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(chunks, citation):\n    i,lo,hi=citation\n    return [lo,hi]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nchunks=[[N,N+5],[N+3,N+8]]\ncheck('citation straddles duplicated prefix',solve(chunks,[1,1,4]),[5,7])\ncheck('entire citation already stitched',solve(chunks,[1,0,2]),None)\ncheck('citation starts after overlap',solve(chunks,[1,2,5]),[5,8])\ncheck('first chunk unchanged',solve(chunks,[0,1,3]),[1,3])\ncheck('touching chunk boundary',solve([[N,N+2],[N+2,N+4]],[1,0,2]),[2,4])\ncheck('empty citation',solve(chunks,[1,2,2]),None)\ncheck('no chunks',solve([],[0,0,1]),None)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"}},"limitations":"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.","method":"Deterministic executable model with adversarial boundary fixtures.","provenance":{"created_by":"Failure Map","dependencies":"Python standard library","family":"w3-chunk-citation-alignment-stitched-overlap-provenance","generated_at":"2026-09-30T16:48:26.712466+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A deterministic citation bookkeeping model isolates source attribution from rendering and retrieval.","root_cause":"Chunk-local ranges are copied into output coordinates without removing source text covered by an earlier chunk.","sha256":"3b1fb4101529e0c734b61893c52a084bad160f2bd26a6b57ba306d14364a9c69","title":"Overlapping chunk citations include the already stitched prefix · case 01","variant":1,"variant_policy":"The fixture code references N, supplied as 1 through 5. Fixed boundary checks may repeat. These records share one mechanism and must remain together in evaluation splits.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":26.912,"exit_code":1,"observations":[{"actual":[6,8],"check":"citation straddles duplicated prefix","expected":[5,7],"passed":false},{"actual":null,"check":"entire citation already stitched","expected":null,"passed":true},{"actual":[6,9],"check":"citation starts after overlap","expected":[5,8],"passed":false},{"actual":[2,4],"check":"first chunk unchanged","expected":[1,3],"passed":false},{"actual":[3,5],"check":"touching chunk boundary","expected":[2,4],"passed":false},{"actual":null,"check":"empty citation","expected":null,"passed":true},{"actual":null,"check":"no chunks","expected":null,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"citation straddles duplicated prefix\", \"actual\": [6, 8], \"expected\": [5, 7], \"passed\": false}, {\"check\": \"entire citation already stitched\", \"actual\": null, \"expected\": null, \"passed\": true}, {\"check\": \"citation starts after overlap\", \"actual\": [6, 9], \"expected\": [5, 8], \"passed\": false}, {\"check\": \"first chunk unchanged\", \"actual\": [2, 4], \"expected\": [1, 3], \"passed\": false}, {\"check\": \"touching chunk boundary\", \"actual\": [3, 5], \"expected\": [2, 4], \"passed\": false}, {\"check\": \"empty citation\", \"actual\": null, \"expected\": null, \"passed\": true}, {\"check\": \"no chunks\", \"actual\": null, \"expected\": null, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":27.123,"exit_code":1,"observations":[{"actual":[1,4],"check":"citation straddles duplicated prefix","expected":[5,7],"passed":false},{"actual":[0,2],"check":"entire citation already stitched","expected":null,"passed":false},{"actual":[2,5],"check":"citation starts after overlap","expected":[5,8],"passed":false},{"actual":[1,3],"check":"first chunk unchanged","expected":[1,3],"passed":true},{"actual":[0,2],"check":"touching chunk boundary","expected":[2,4],"passed":false},{"actual":[2,2],"check":"empty citation","expected":null,"passed":false},{"actual":[0,1],"check":"no chunks","expected":null,"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"citation straddles duplicated prefix\", \"actual\": [1, 4], \"expected\": [5, 7], \"passed\": false}, {\"check\": \"entire citation already stitched\", \"actual\": [0, 2], \"expected\": null, \"passed\": false}, {\"check\": \"citation starts after overlap\", \"actual\": [2, 5], \"expected\": [5, 8], \"passed\": false}, {\"check\": \"first chunk unchanged\", \"actual\": [1, 3], \"expected\": [1, 3], \"passed\": true}, {\"check\": \"touching chunk boundary\", \"actual\": [0, 2], \"expected\": [2, 4], \"passed\": false}, {\"check\": \"empty citation\", \"actual\": [2, 2], \"expected\": null, \"passed\": false}, {\"check\": \"no chunks\", \"actual\": [0, 1], \"expected\": null, \"passed\": false}], \"passed\": false}\n"}},"member_only":{"stages":["fixed"],"fields":["implementations.fixed","verification.fixed","harness","repair"],"note":"The verified repair, its recorded checks, the repair description, and the scoring harness are available to members."}}