FAILURE MAP
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FA-50116 / PCM sample encoding / Open access

Pcm escaped residuals: escape literal · case 01

An escaped absolute PCM anchor is added as a residual.

Verified by executionVariant 1 · 8 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

An escaped absolute PCM anchor is added as a residual.

VERIFIED REPAIR

Use the stated conversion contract at escape literal.

Unsuccessful approach: Adding the block seed still fails to replace predictor with the literal amplitude.

Case contract

Decode a stipulated PCM residual stream with an escape token followed by an absolute sample anchor; report a dangling escape without losing valid prefix state.

Why this case matters

Offline PCM interchange uses these exact bounded packet and sample representation decisions.

1 / The failure

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(tokens, initial, escape):
    out=[]
    previous=initial
    cursor=0
    while cursor<len(tokens):
        token=tokens[cursor]
        cursor+=1
        if token==escape:
            if cursor==len(tokens):
                return [out,previous,'truncated']
            previous+=tokens[cursor]
            cursor+=1
        else:
            previous+=token
        out.append(previous)
    return [out,previous,'ok']
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('oracle 1', solve(*([1, 99, 20, -2], 10, 99)), [[11, 20, 18], 18, 'ok'])
check('oracle 2', solve(*([99, -5, 2], 1, 99)), [[-5, -3], -3, 'ok'])
check('oracle 3', solve(*([1, 99], 3, 99)), [[4], 4, 'truncated'])
check('oracle 4', solve(*([], 4, 99)), [[], 4, 'ok'])
check('oracle 5', solve(*([0, 1, 0], 2, 99)), [[2, 3, 3], 3, 'ok'])
check('oracle 6', solve(*([8, 9, 0], 1, 7)), [[9, 18, 18], 18, 'ok'])
check('oracle 7', solve(*([7, 3, 7, 8], 0, 7)), [[3, 8], 8, 'ok'])
if N == 1: check('variant packet 1', solve(*[[1, 99, 20, -2, 1, 99, 20, -2], 10, 99]), [[11, 20, 18, 19, 20, 18], 18, 'ok'])
if N == 2: check('variant packet 2', solve(*[[1, 99, 20, -2, 1, 99, 20, -2, 1, 99, 20, -2], 10, 99]), [[11, 20, 18, 19, 20, 18, 19, 20, 18], 18, 'ok'])
if N == 3: check('variant packet 3', solve(*[[1, 99, 20, -2, 1, 99, 20, -2, 1, 99, 20, -2, 1, 99, 20, -2], 10, 99]), [[11, 20, 18, 19, 20, 18, 19, 20, 18, 19, 20, 18], 18, 'ok'])
if N == 4: check('variant packet 4', solve(*[[1, 99, 20, -2, 1, 99, 20, -2, 1, 99, 20, -2, 1, 99, 20, -2, 1, 99, 20, -2], 10, 99]), [[11, 20, 18, 19, 20, 18, 19, 20, 18, 19, 20, 18, 19, 20, 18], 18, 'ok'])
if N == 5: check('variant packet 5', solve(*[[1, 99, 20, -2, 1, 99, 20, -2, 1, 99, 20, -2, 1, 99, 20, -2, 1, 99, 20, -2, 1, 99, 20, -2], 10, 99]), [[11, 20, 18, 19, 20, 18, 19, 20, 18, 19, 20, 18, 19, 20, 18, 19, 20, 18], 18, 'ok'])
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 fixtureActualExpectedOutcome
oracle 1[[11, 31, 29], 29, 'ok'][[11, 20, 18], 18, 'ok']Failed
oracle 2[[-4, -2], -2, 'ok'][[-5, -3], -3, 'ok']Failed
oracle 3[[4], 4, 'truncated'][[4], 4, 'truncated']Passed
oracle 4[[], 4, 'ok'][[], 4, 'ok']Passed
oracle 5[[2, 3, 3], 3, 'ok'][[2, 3, 3], 3, 'ok']Passed
oracle 6[[9, 18, 18], 18, 'ok'][[9, 18, 18], 18, 'ok']Passed
oracle 7[[3, 11], 11, 'ok'][[3, 8], 8, 'ok']Failed
variant packet 1[[11, 31, 29, 30, 50, 48], 48, 'ok'][[11, 20, 18, 19, 20, 18], 18, 'ok']Failed

SHA-256 / 2945425e1b300bee36fb54ed27e3a78c2fbd575fcd0d338e3ebab864289daa0d

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(tokens, initial, escape):
    out=[]
    previous=initial
    cursor=0
    while cursor<len(tokens):
        token=tokens[cursor]
        cursor+=1
        if token==escape:
            if cursor==len(tokens):
                return [out,previous,'truncated']
            previous=initial+tokens[cursor]
            cursor+=1
        else:
            previous+=token
        out.append(previous)
    return [out,previous,'ok']
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('oracle 1', solve(*([1, 99, 20, -2], 10, 99)), [[11, 20, 18], 18, 'ok'])
check('oracle 2', solve(*([99, -5, 2], 1, 99)), [[-5, -3], -3, 'ok'])
check('oracle 3', solve(*([1, 99], 3, 99)), [[4], 4, 'truncated'])
check('oracle 4', solve(*([], 4, 99)), [[], 4, 'ok'])
check('oracle 5', solve(*([0, 1, 0], 2, 99)), [[2, 3, 3], 3, 'ok'])
check('oracle 6', solve(*([8, 9, 0], 1, 7)), [[9, 18, 18], 18, 'ok'])
check('oracle 7', solve(*([7, 3, 7, 8], 0, 7)), [[3, 8], 8, 'ok'])
if N == 1: check('variant packet 1', solve(*[[1, 99, 20, -2, 1, 99, 20, -2], 10, 99]), [[11, 20, 18, 19, 20, 18], 18, 'ok'])
if N == 2: check('variant packet 2', solve(*[[1, 99, 20, -2, 1, 99, 20, -2, 1, 99, 20, -2], 10, 99]), [[11, 20, 18, 19, 20, 18, 19, 20, 18], 18, 'ok'])
if N == 3: check('variant packet 3', solve(*[[1, 99, 20, -2, 1, 99, 20, -2, 1, 99, 20, -2, 1, 99, 20, -2], 10, 99]), [[11, 20, 18, 19, 20, 18, 19, 20, 18, 19, 20, 18], 18, 'ok'])
if N == 4: check('variant packet 4', solve(*[[1, 99, 20, -2, 1, 99, 20, -2, 1, 99, 20, -2, 1, 99, 20, -2, 1, 99, 20, -2], 10, 99]), [[11, 20, 18, 19, 20, 18, 19, 20, 18, 19, 20, 18, 19, 20, 18], 18, 'ok'])
if N == 5: check('variant packet 5', solve(*[[1, 99, 20, -2, 1, 99, 20, -2, 1, 99, 20, -2, 1, 99, 20, -2, 1, 99, 20, -2, 1, 99, 20, -2], 10, 99]), [[11, 20, 18, 19, 20, 18, 19, 20, 18, 19, 20, 18, 19, 20, 18, 19, 20, 18], 18, 'ok'])
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 fixtureActualExpectedOutcome
oracle 1[[11, 30, 28], 28, 'ok'][[11, 20, 18], 18, 'ok']Failed
oracle 2[[-4, -2], -2, 'ok'][[-5, -3], -3, 'ok']Failed
oracle 3[[4], 4, 'truncated'][[4], 4, 'truncated']Passed
oracle 4[[], 4, 'ok'][[], 4, 'ok']Passed
oracle 5[[2, 3, 3], 3, 'ok'][[2, 3, 3], 3, 'ok']Passed
oracle 6[[9, 18, 18], 18, 'ok'][[9, 18, 18], 18, 'ok']Passed
oracle 7[[3, 8], 8, 'ok'][[3, 8], 8, 'ok']Passed
variant packet 1[[11, 30, 28, 29, 30, 28], 28, 'ok'][[11, 20, 18, 19, 20, 18], 18, 'ok']Failed

SHA-256 / 78fb2327611eec395aea2854c1c26503879a992a6f11cc124ee61b8fc047f3d3

3 / The verified repair

Exit 0
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(tokens, initial, escape):
    out=[]
    previous=initial
    cursor=0
    while cursor<len(tokens):
        token=tokens[cursor]
        cursor+=1
        if token==escape:
            if cursor==len(tokens):
                return [out,previous,'truncated']
            previous=tokens[cursor]
            cursor+=1
        else:
            previous+=token
        out.append(previous)
    return [out,previous,'ok']
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('oracle 1', solve(*([1, 99, 20, -2], 10, 99)), [[11, 20, 18], 18, 'ok'])
check('oracle 2', solve(*([99, -5, 2], 1, 99)), [[-5, -3], -3, 'ok'])
check('oracle 3', solve(*([1, 99], 3, 99)), [[4], 4, 'truncated'])
check('oracle 4', solve(*([], 4, 99)), [[], 4, 'ok'])
check('oracle 5', solve(*([0, 1, 0], 2, 99)), [[2, 3, 3], 3, 'ok'])
check('oracle 6', solve(*([8, 9, 0], 1, 7)), [[9, 18, 18], 18, 'ok'])
check('oracle 7', solve(*([7, 3, 7, 8], 0, 7)), [[3, 8], 8, 'ok'])
if N == 1: check('variant packet 1', solve(*[[1, 99, 20, -2, 1, 99, 20, -2], 10, 99]), [[11, 20, 18, 19, 20, 18], 18, 'ok'])
if N == 2: check('variant packet 2', solve(*[[1, 99, 20, -2, 1, 99, 20, -2, 1, 99, 20, -2], 10, 99]), [[11, 20, 18, 19, 20, 18, 19, 20, 18], 18, 'ok'])
if N == 3: check('variant packet 3', solve(*[[1, 99, 20, -2, 1, 99, 20, -2, 1, 99, 20, -2, 1, 99, 20, -2], 10, 99]), [[11, 20, 18, 19, 20, 18, 19, 20, 18, 19, 20, 18], 18, 'ok'])
if N == 4: check('variant packet 4', solve(*[[1, 99, 20, -2, 1, 99, 20, -2, 1, 99, 20, -2, 1, 99, 20, -2, 1, 99, 20, -2], 10, 99]), [[11, 20, 18, 19, 20, 18, 19, 20, 18, 19, 20, 18, 19, 20, 18], 18, 'ok'])
if N == 5: check('variant packet 5', solve(*[[1, 99, 20, -2, 1, 99, 20, -2, 1, 99, 20, -2, 1, 99, 20, -2, 1, 99, 20, -2, 1, 99, 20, -2], 10, 99]), [[11, 20, 18, 19, 20, 18, 19, 20, 18, 19, 20, 18, 19, 20, 18, 19, 20, 18], 18, 'ok'])
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 fixtureActualExpectedOutcome
oracle 1[[11, 20, 18], 18, 'ok'][[11, 20, 18], 18, 'ok']Passed
oracle 2[[-5, -3], -3, 'ok'][[-5, -3], -3, 'ok']Passed
oracle 3[[4], 4, 'truncated'][[4], 4, 'truncated']Passed
oracle 4[[], 4, 'ok'][[], 4, 'ok']Passed
oracle 5[[2, 3, 3], 3, 'ok'][[2, 3, 3], 3, 'ok']Passed
oracle 6[[9, 18, 18], 18, 'ok'][[9, 18, 18], 18, 'ok']Passed
oracle 7[[3, 8], 8, 'ok'][[3, 8], 8, 'ok']Passed
variant packet 1[[11, 20, 18, 19, 20, 18], 18, 'ok'][[11, 20, 18, 19, 20, 18], 18, 'ok']Passed

SHA-256 / 8fb1ef408938fe1aaa436580f6ed38ab4209efae2a48f494c76437794a8db3ec

Verification & scope

Stipulated finite model; no claim of hardware timing or full file-format conformance. 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 2026-09-29T14:45:06.152015+00:00.

Case digest / e58c7d8c8dcfcd4b1ba59a732fd8cc9378e203ecdc8e0a404f9e08180e92185b