FA-8676 / Client navigation / Open access

Navigation active-link matching: Sibling prefixes mark unrelated navigation items active · case 01

Sibling prefixes mark unrelated navigation items active.

Verified by executionVariant 1 · 11 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The segment operation uses `path.startswith(link)` where the contract requires `path.startswith(link + '/')`.

VERIFIED REPAIR

Implement the segment operation as `path.startswith(link + '/')`.

Unsuccessful approach: Substring matching also activates nested unrelated segment names.

Case contract

Ignore URL query and fragment; normalize trailing slashes with root preserved; honor case policy; section matches require a slash boundary and root matches exactly.

Why this case matters

A deterministic model of navigation active-link matching; this isolates one interface invariant without requiring a browser.

1 / The failure

Exit 1

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

N = 1
observations = []
def solve(path, link, exact, case_sensitive):
    path = path.split('?', 1)[0].split('#', 1)[0]
    link = link.rstrip('/') or '/'
    path = path.rstrip('/') or '/'
    if not case_sensitive: path, link = path.casefold(), link.casefold()
    if exact or link == '/': return path == link
    return path == link or path.startswith(link)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('query', solve('/docs?x=1', '/docs', True, True), True)
check('fragment', solve('/docs#intro', '/docs', True, True), True)
check('slash', solve('/docs', '/docs/', True, True), True)
check('root', solve('/docs', '/', False, True), False)
check('root itself', solve('/', '/', True, True), True)
check('fold', solve("/DOCS", "/docs", True, False), True)
check('sensitive', solve("/DOCS", "/docs", True, True), False)
check('child', solve('/docs/a', '/docs', False, True), True)
check('prefix sibling', solve('/docstring', '/docs', False, True), False)
check('parameterized route segment', solve('/section'+str(N)+'/child','/section'+str(N),False,True), True)
for repetition in range(N):
    check('repeat prefix sibling', solve('/docstring', '/docs', False, True), False)
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
query	`True`	`True`	Passed
fragment	`True`	`True`	Passed
slash	`True`	`True`	Passed
root	`False`	`False`	Passed
root itself	`True`	`True`	Passed
fold	`True`	`True`	Passed
sensitive	`False`	`False`	Passed
child	`True`	`True`	Passed
prefix sibling	`True`	`False`	Failed
parameterized route segment	`True`	`True`	Passed
repeat prefix sibling	`True`	`False`	Failed

SHA-256 / ee64f88d5b7f9d5e44d6bd53c93087bb51b8156baac29ea7b33a2c06116d4302

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(path, link, exact, case_sensitive):
    path = path.split('?', 1)[0].split('#', 1)[0]
    link = link.rstrip('/') or '/'
    path = path.rstrip('/') or '/'
    if not case_sensitive: path, link = path.casefold(), link.casefold()
    if exact or link == '/': return path == link
    return path == link or link in path
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('query', solve('/docs?x=1', '/docs', True, True), True)
check('fragment', solve('/docs#intro', '/docs', True, True), True)
check('slash', solve('/docs', '/docs/', True, True), True)
check('root', solve('/docs', '/', False, True), False)
check('root itself', solve('/', '/', True, True), True)
check('fold', solve("/DOCS", "/docs", True, False), True)
check('sensitive', solve("/DOCS", "/docs", True, True), False)
check('child', solve('/docs/a', '/docs', False, True), True)
check('prefix sibling', solve('/docstring', '/docs', False, True), False)
check('parameterized route segment', solve('/section'+str(N)+'/child','/section'+str(N),False,True), True)
for repetition in range(N):
    check('repeat prefix sibling', solve('/docstring', '/docs', False, True), False)
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
query	`True`	`True`	Passed
fragment	`True`	`True`	Passed
slash	`True`	`True`	Passed
root	`False`	`False`	Passed
root itself	`True`	`True`	Passed
fold	`True`	`True`	Passed
sensitive	`False`	`False`	Passed
child	`True`	`True`	Passed
prefix sibling	`True`	`False`	Failed
parameterized route segment	`True`	`True`	Passed
repeat prefix sibling	`True`	`False`	Failed

SHA-256 / 2965d05e45eb5ad29245c5956cb9343830832df57e47b10cec642a7da2e5ea00

3 / The verified repair

Exit 0

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

N = 1
observations = []
def solve(path, link, exact, case_sensitive):
    path = path.split('?', 1)[0].split('#', 1)[0]
    link = link.rstrip('/') or '/'
    path = path.rstrip('/') or '/'
    if not case_sensitive: path, link = path.casefold(), link.casefold()
    if exact or link == '/': return path == link
    return path == link or path.startswith(link + '/')
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('query', solve('/docs?x=1', '/docs', True, True), True)
check('fragment', solve('/docs#intro', '/docs', True, True), True)
check('slash', solve('/docs', '/docs/', True, True), True)
check('root', solve('/docs', '/', False, True), False)
check('root itself', solve('/', '/', True, True), True)
check('fold', solve("/DOCS", "/docs", True, False), True)
check('sensitive', solve("/DOCS", "/docs", True, True), False)
check('child', solve('/docs/a', '/docs', False, True), True)
check('prefix sibling', solve('/docstring', '/docs', False, True), False)
check('parameterized route segment', solve('/section'+str(N)+'/child','/section'+str(N),False,True), True)
for repetition in range(N):
    check('repeat prefix sibling', solve('/docstring', '/docs', False, True), False)
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
query	`True`	`True`	Passed
fragment	`True`	`True`	Passed
slash	`True`	`True`	Passed
root	`False`	`False`	Passed
root itself	`True`	`True`	Passed
fold	`True`	`True`	Passed
sensitive	`False`	`False`	Passed
child	`True`	`True`	Passed
prefix sibling	`False`	`False`	Passed
parameterized route segment	`True`	`True`	Passed
repeat prefix sibling	`False`	`False`	Passed

SHA-256 / 5f4fba5b804be1fd36d31301a615d617455f49d9f15a48c72b61e31b818c9a6b

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 2026-09-29T14:38:23.444198+00:00.

Case digest / abc5128f2c0eb77c526ad4cd7829a6c87571d891f4c7df7c913142c84575134d