FA-26406 / HTTP ranges / Open access

Explicit identity exclusion prevents uncompressed range fallback · case 01

Explicit identity exclusion prevents uncompressed range fallback.

Verified by executionVariant 1 · 6 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The identity-quality-zero decision uses return ["compressed206" if compressed_seekable else "identity206",payload].

THE FAILURE

The identity-quality-zero decision uses return ["compressed206" if compressed_seekable else "identity206",payload].

Unsuccessful approach: The partial repair uses return ["compressed206",payload] if compressed_seekable else (["identity206",payload] if identity_q>=0 else ["406",""]), which still violates the stated contract.

Case contract

Local negotiation returns compressed206 if seekable; otherwise identity206 only for positive identity quality, else 406. payload propagates for accepted responses.

Why this case matters

Range responses combine representation identity, conditional requests, framing, and partial-object state.

1 / The failure

Exit 1

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

N = 1
observations = []
def solve(identity_q, compressed_seekable, payload):
    return ["compressed206" if compressed_seekable else "identity206",payload]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('identity-quality-zero fixture 0', solve(0,False,"p"*N), ["406",""])
check('identity-quality-zero fixture 1', solve(1,False,"p"*N), ["identity206","p"*N])
check('identity-quality-zero fixture 2', solve(0,True,"p"), ["compressed206","p"])
check('identity-quality-zero fixture 3', solve(0.5,False,"p"), ["identity206","p"])
check('identity-quality-zero fixture 4', solve(1,True,""), ["compressed206",""])
check('identity-quality-zero fixture 5', solve(0,False,""), ["406",""])
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
identity-quality-zero fixture 0	`['identity206', 'p']`	`['406', '']`	Failed
identity-quality-zero fixture 1	`['identity206', 'p']`	`['identity206', 'p']`	Passed
identity-quality-zero fixture 2	`['compressed206', 'p']`	`['compressed206', 'p']`	Passed
identity-quality-zero fixture 3	`['identity206', 'p']`	`['identity206', 'p']`	Passed
identity-quality-zero fixture 4	`['compressed206', '']`	`['compressed206', '']`	Passed
identity-quality-zero fixture 5	`['identity206', '']`	`['406', '']`	Failed

SHA-256 / a401bbf69b762bdc90ae8c210327d15e3514663224afc61f4d159077f4e880c5

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(identity_q, compressed_seekable, payload):
    return ["compressed206",payload] if compressed_seekable else (["identity206",payload] if identity_q>=0 else ["406",""])
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('identity-quality-zero fixture 0', solve(0,False,"p"*N), ["406",""])
check('identity-quality-zero fixture 1', solve(1,False,"p"*N), ["identity206","p"*N])
check('identity-quality-zero fixture 2', solve(0,True,"p"), ["compressed206","p"])
check('identity-quality-zero fixture 3', solve(0.5,False,"p"), ["identity206","p"])
check('identity-quality-zero fixture 4', solve(1,True,""), ["compressed206",""])
check('identity-quality-zero fixture 5', solve(0,False,""), ["406",""])
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
identity-quality-zero fixture 0	`['identity206', 'p']`	`['406', '']`	Failed
identity-quality-zero fixture 1	`['identity206', 'p']`	`['identity206', 'p']`	Passed
identity-quality-zero fixture 2	`['compressed206', 'p']`	`['compressed206', 'p']`	Passed
identity-quality-zero fixture 3	`['identity206', 'p']`	`['identity206', 'p']`	Passed
identity-quality-zero fixture 4	`['compressed206', '']`	`['compressed206', '']`	Passed
identity-quality-zero fixture 5	`['identity206', '']`	`['406', '']`	Failed

SHA-256 / 6aff8f3c748ea34d3872c8aee114650357d712769efe8c9f842fbfc804f75187

HELD IN THE MEMBER ARCHIVE

The verified repair and its recorded checks are member-only.

This mechanism has 6 recorded checks per implementation. The open-access tier publishes the failure and the unsuccessful fix; the repaired source that passes every check, and the observations that prove it, are available to members.

Every case sharing this mechanism uses the same contract and the same repair, so this one record is held back for all of them.

Member access is invitation-based. Sign in with your invited account to inspect the repair.

Verification & scope

Deterministic simplified range service, with stipulated local policies and already parsed trusted inputs; not a complete HTTP implementation. 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 2026-09-29T14:41:15.695087+00:00.

Case digest / e161a3fbc2f928077ba07f4ed886a0eee8381500199473fdc0a7fac2a1fd45b5