FA-10676 / Raster clipping / Open access

Span merge touching · case 01

Touching coverage spans remain separate and create redundant raster work.

Verified by executionVariant 1 · 4 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

Touching coverage spans remain separate and create redundant raster work.

VERIFIED REPAIR

Use the stage contract: Return sorted disjoint half-open raster spans after dropping zero/negative lengths and coalescing both overlapping and adjacent spans.

Unsuccessful approach: Replacing the merged end with a contained span end shrinks coverage and retains empty spans.

Case contract

Return sorted disjoint half-open raster spans after dropping zero/negative lengths and coalescing both overlapping and adjacent spans.

Why this case matters

A deterministic software graphics stage with explicit channel and coordinate conventions; no hardware, device profile or API behavior is inferred.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(spans):
    out=[]
    for left,right in sorted(spans):
        if right<=left: continue
        if out and left<out[-1][1]: out[-1][1]=max(out[-1][1],right)
        else: out.append([left,right])
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1', solve(*([[0, 2], [2, 4]],)), [[0, 4]])
check('fixture 2', solve(*([[0, 5], [1, 2]],)), [[0, 5]])
check('fixture 3', solve(*([[3, 3], [1, 2]],)), [[1, 2]])
check('fixture 4', solve(*([],)), [])
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
fixture 1	`[[0, 2], [2, 4]]`	`[[0, 4]]`	Failed
fixture 2	`[[0, 5]]`	`[[0, 5]]`	Passed
fixture 3	`[[1, 2]]`	`[[1, 2]]`	Passed
fixture 4	`[]`	`[]`	Passed

SHA-256 / 001eeec722b5fbb631adb5d8e391219748a25f2196b678036eaa50fafcfa53bf

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(spans):
    out=[]
    for left,right in sorted(spans):
        if out and left<=out[-1][1]: out[-1][1]=right
        else: out.append([left,right])
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1', solve(*([[0, 2], [2, 4]],)), [[0, 4]])
check('fixture 2', solve(*([[0, 5], [1, 2]],)), [[0, 5]])
check('fixture 3', solve(*([[3, 3], [1, 2]],)), [[1, 2]])
check('fixture 4', solve(*([],)), [])
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
fixture 1	`[[0, 4]]`	`[[0, 4]]`	Passed
fixture 2	`[[0, 2]]`	`[[0, 5]]`	Failed
fixture 3	`[[1, 2], [3, 3]]`	`[[1, 2]]`	Failed
fixture 4	`[]`	`[]`	Passed

SHA-256 / 3c18e45a4b141cf169ba23d2b79cd027860f1d74dc22b74289fc311d5849b593

3 / The verified repair

Exit 0

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(spans):
    out=[]
    for left,right in sorted(spans):
        if right<=left: continue
        if out and left<=out[-1][1]: out[-1][1]=max(out[-1][1],right)
        else: out.append([left,right])
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1', solve(*([[0, 2], [2, 4]],)), [[0, 4]])
check('fixture 2', solve(*([[0, 5], [1, 2]],)), [[0, 5]])
check('fixture 3', solve(*([[3, 3], [1, 2]],)), [[1, 2]])
check('fixture 4', solve(*([],)), [])
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
fixture 1	`[[0, 4]]`	`[[0, 4]]`	Passed
fixture 2	`[[0, 5]]`	`[[0, 5]]`	Passed
fixture 3	`[[1, 2]]`	`[[1, 2]]`	Passed
fixture 4	`[]`	`[]`	Passed

SHA-256 / c2987cffcb499c4d39972b54bcb2e4e089cff5b7cc0ea61ff67bb7303156f05c

Verification & scope

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 2026-09-29T14:38:41.200323+00:00.

Case digest / 9a0fda71d0848bd25b9bed1d5781518a1914ee5b32c2218fab530e32caab4509