FA-11266 / Media timeline seeking / Open access
Timestamp wrap unroll nearest forward · case 01
A wrapped media counter is treated as an absolute time and jumps backward.
ROOT CAUSE
A wrapped media counter is treated as an absolute time and jumps backward.
VERIFIED REPAIR
Preserve the media contract: For monotonic sample delivery with less than one wrap between observations, map raw counter in [0,modulus) to the smallest timestamp >=last with that residue.
Unsuccessful approach: Adding raw residue to the last timestamp overcounts progress inside a cycle.
Case contract
For monotonic sample delivery with less than one wrap between observations, map raw counter in [0,modulus) to the smallest timestamp >=last with that residue.
Why this case matters
A deterministic local media controller stage; metadata and downloaded data are supplied explicitly. No external player, service or codec is required.
1 / The failure
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(last, raw, modulus):
return raw
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*(14, 1, 16)),17)
check('fixture 2',solve(*(17, 3, 16)),19)
check('fixture 3',solve(*(3, 3, 16)),3)
check('fixture 4',solve(*(0, 5, 16)),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 |
|---|---|---|---|
| fixture 1 | 1 | 17 | Failed |
| fixture 2 | 3 | 19 | Failed |
| fixture 3 | 3 | 3 | Passed |
| fixture 4 | 5 | 5 | Passed |
SHA-256 / c2f2b31de9aae4977aeb5c9b0df671f4027784e208dd84ef7ca70aac9c01e17a
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(last, raw, modulus):
return last+raw
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*(14, 1, 16)),17)
check('fixture 2',solve(*(17, 3, 16)),19)
check('fixture 3',solve(*(3, 3, 16)),3)
check('fixture 4',solve(*(0, 5, 16)),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 |
|---|---|---|---|
| fixture 1 | 15 | 17 | Failed |
| fixture 2 | 20 | 19 | Failed |
| fixture 3 | 6 | 3 | Failed |
| fixture 4 | 5 | 5 | Passed |
SHA-256 / 49500f442179d32cf0ea64000dd5102840d8c51ccd5fc6c3ffb7a21d0662396e
3 / The verified repair
Exit 0"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(last, raw, modulus):
return last+(raw-last%modulus)%modulus
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*(14, 1, 16)),17)
check('fixture 2',solve(*(17, 3, 16)),19)
check('fixture 3',solve(*(3, 3, 16)),3)
check('fixture 4',solve(*(0, 5, 16)),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 |
|---|---|---|---|
| fixture 1 | 17 | 17 | Passed |
| fixture 2 | 19 | 19 | Passed |
| fixture 3 | 3 | 3 | Passed |
| fixture 4 | 5 | 5 | Passed |
SHA-256 / 09dc1878f98212fc12fb21066d90ca4e25ebe97cec882b800203cbb8aca3cadc
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 2026-09-29T14:38:46.426760+00:00.
Case digest / 9295ab4342f1c1fa02bc0f7a97a3cb71101abe66141f66f8f95b6b22cba31570