FA-7481 / Multiplexed protocols / Open access

Http2 padding consumes flow control credit · case 01

Http2 padding consumes flow control credit.

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

ROOT CAUSE

The faulty implementation uses `data` for the http2-padding-consumes-flow-control-credit decision.

VERIFIED REPAIR

Apply the explicit http2-padding-consumes-flow-control-credit contract, including the tested boundary and negative cases.

Unsuccessful approach: The attempted repair uses `data+padding` and still violates a separate fixture.

Case contract

Bounded offline decision model: http2 padding consumes flow control credit. Inputs are already validated protocol fields; the explicit fixtures define the supported policy, not a complete protocol implementation.

Why this case matters

This deterministic multiplexed protocols model isolates the http2-padding-consumes-flow-control-credit policy at a network component boundary.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import ipaddress
import re
from urllib.parse import urlsplit, urljoin
N = 1
observations = []
def solve(data, padding, has_padding):
    return data
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(10, 3, True), 14)", "check('fixture 2', solve(10, 0, True), 11)", "check('fixture 3', solve(10, 0, False), 10)", "check('fixture 4', solve(0, 0, False), 0)"]
for _line in _fixtures[N % len(_fixtures):] + _fixtures[:N % len(_fixtures)]:
    exec(_line)
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 2	`10`	`11`	Failed
fixture 3	`10`	`10`	Passed
fixture 4	`0`	`0`	Passed
fixture 1	`10`	`14`	Failed

SHA-256 / 1a89fd89db1f58ed04c277a5570ce5c10de3b777efaaf1859fb8cd408936d1a9

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import ipaddress
import re
from urllib.parse import urlsplit, urljoin
N = 1
observations = []
def solve(data, padding, has_padding):
    return data+padding
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(10, 3, True), 14)", "check('fixture 2', solve(10, 0, True), 11)", "check('fixture 3', solve(10, 0, False), 10)", "check('fixture 4', solve(0, 0, False), 0)"]
for _line in _fixtures[N % len(_fixtures):] + _fixtures[:N % len(_fixtures)]:
    exec(_line)
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 2	`10`	`11`	Failed
fixture 3	`10`	`10`	Passed
fixture 4	`0`	`0`	Passed
fixture 1	`13`	`14`	Failed

SHA-256 / 18140804c72960bef0016a12e9a5f112aca22f03defecdf9e27b9c30524e5010

3 / The verified repair

Exit 0

"""Failure Map reference implementation. Python standard library only."""
import json
import ipaddress
import re
from urllib.parse import urlsplit, urljoin
N = 1
observations = []
def solve(data, padding, has_padding):
    return data+padding+int(has_padding)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(10, 3, True), 14)", "check('fixture 2', solve(10, 0, True), 11)", "check('fixture 3', solve(10, 0, False), 10)", "check('fixture 4', solve(0, 0, False), 0)"]
for _line in _fixtures[N % len(_fixtures):] + _fixtures[:N % len(_fixtures)]:
    exec(_line)
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 2	`11`	`11`	Passed
fixture 3	`10`	`10`	Passed
fixture 4	`0`	`0`	Passed
fixture 1	`14`	`14`	Passed

SHA-256 / fa65284aecbb40ee7576854fffe2060fba996eefbc08434d186a8b85c4cbe00b

Verification & scope

Bounded deterministic policy model over validated inputs; not a complete protocol stack or an interoperability claim. The five variants rotate the same explicit fixture set. 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 2026-09-29T14:38:12.416174+00:00.

Case digest / 7031272511c067cb5e6b127684b3f3468d7f13c6f2f25eaa3e8453a04521210b