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FA-80411 / Bidirectional text layout / Open access

Weak type resolution: European number context start · case 01

Numbers at the start of a sequence ignore the sequence start type.

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

ROOT CAUSE

W7 starts its last-strong search from R instead of sos.

VERIFIED REPAIR

Initialise the W7 context with sos.

Unsuccessful approach: Initialising with L is the opposite constant, still ignoring sos.

Case contract

Input [classes of one isolating run sequence, sos]. W1 NSM takes the previous type (sos at start; ON after LRI/RLI/FSI/PDI). W2 EN after the last strong AL becomes AN. W3 AL->R. W4 a single ES between EN and EN -> EN; a single CS between two numbers of the same type takes that type. W5 a run of ET adjacent to EN -> EN. W6 remaining ES/ET/CS -> ON. W7 EN whose last strong (sos at start) is L -> L. Return resolved classes.

Why this case matters

Mixed right-to-left and left-to-right text must resolve levels and visual order exactly, or words, numbers and carets land in the wrong place.

1 / The failure

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

N = 1
observations = []
def solve(x):
    types, sos = x
    t = list(types)
    n = len(t)
    prev = sos
    for i in range(n):
        if t[i] == 'NSM':
            t[i] = 'ON' if prev in ('LRI', 'RLI', 'FSI', 'PDI') else prev
        prev = t[i]
    last_strong = 'R'
    for i in range(n):
        if t[i] in ('L', 'R', 'AL'):
            last_strong = t[i]
        elif t[i] == 'EN' and last_strong == 'AL':
            t[i] = 'AN'
    t = ['R' if c == 'AL' else c for c in t]
    for i in range(1, n - 1):
        if t[i] == 'ES' and t[i - 1] == 'EN' and t[i + 1] == 'EN':
            t[i] = 'EN'
        elif t[i] == 'CS' and t[i - 1] == t[i + 1] and t[i - 1] in ('EN', 'AN'):
            t[i] = t[i - 1]
    i = 0
    while i < n:
        if t[i] == 'ET':
            j = i
            while j < n and t[j] == 'ET':
                j += 1
            if (i > 0 and t[i - 1] == 'EN') or (j < n and t[j] == 'EN'):
                for k in range(i, j):
                    t[k] = 'EN'
            i = j
        else:
            i += 1
    t = ['ON' if c in ('ES', 'ET', 'CS') else c for c in t]
    strong = 'R'
    for i in range(n):
        if t[i] in ('L', 'R'):
            strong = t[i]
        elif t[i] == 'EN' and strong == 'L':
            t[i] = 'L'
    return t
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: European number context start', [['ON', 'EN'], 'L'], ['ON', 'L']), ('regression: European number context start', [['EN', 'NSM'], 'L'], ['L', 'L']), ('partial-repair probe', [['ES', 'ON', 'ET', 'CS', 'EN', 'EN', 'NSM', 'LRI', 'CS', 'PDI', 'EN'], 'R'], ['ON', 'ON', 'ON', 'ON', 'EN', 'EN', 'EN', 'LRI', 'ON', 'PDI', 'EN']), ('partial-repair probe', [['ET', 'ES', 'NSM', 'CS', 'EN', 'CS', 'EN'], 'R'], ['ON', 'ON', 'ON', 'ON', 'EN', 'EN', 'EN']), ('NSM after isolate initiator', [['LRI', 'NSM', 'L', 'PDI'], 'R'], ['LRI', 'ON', 'L', 'PDI']), ('Arabic number context', [['AL', 'EN', 'CS', 'EN'], 'L'], ['R', 'AN', 'AN', 'AN']), ('control layout', [['LRI', 'WS', 'ET'], 'R'], ['LRI', 'WS', 'ON']), ('control layout', [['AN', 'AL', 'L', 'EN', 'EN', 'AL', 'WS', 'ET'], 'R'], ['AN', 'R', 'L', 'L', 'L', 'R', 'WS', 'ON'])], [('regression: European number context start', [['EN', 'ON', 'R', 'AL', 'ES', 'AL'], 'L'], ['L', 'ON', 'R', 'R', 'ON', 'R']), ('regression: European number context start', [['LRI', 'EN', 'R', 'NSM', 'R', 'L', 'ON', 'EN'], 'L'], ['LRI', 'L', 'R', 'R', 'R', 'L', 'ON', 'L']), ('partial-repair probe', [['AN', 'EN'], 'R'], ['AN', 'EN']), ('partial-repair probe', [['CS', 'EN', 'EN'], 'R'], ['ON', 'EN', 'EN']), ('Arabic number context', [['AL', 'EN', 'CS', 'EN'], 'L'], ['R', 'AN', 'AN', 'AN']), ('NSM chain after R', [['R', 'NSM', 'NSM', 'EN'], 'L'], ['R', 'R', 'R', 'EN']), ('control layout', [['ES', 'NSM', 'AL'], 'R'], ['ON', 'ON', 'R']), ('control layout', [['CS', 'R', 'AN', 'L', 'NSM', 'EN', 'EN', 'AN', 'ET', 'AL', 'WS'], 'R'], ['ON', 'R', 'AN', 'L', 'L', 'L', 'L', 'AN', 'ON', 'R', 'WS'])], [('regression: European number context start', [['ES', 'EN'], 'L'], ['ON', 'L']), ('regression: European number context start', [['EN', 'AN', 'LRI', 'ES', 'ON', 'L', 'EN', 'AL', 'R'], 'L'], ['L', 'AN', 'LRI', 'ON', 'ON', 'L', 'L', 'R', 'R']), ('partial-repair probe', [['CS', 'EN', 'PDI', 'ES', 'ET', 'R'], 'R'], ['ON', 'EN', 'PDI', 'ON', 'ON', 'R']), ('partial-repair probe', [['AN', 'AN', 'CS', 'EN', 'ON', 'EN', 'EN'], 'R'], ['AN', 'AN', 'ON', 'EN', 'ON', 'EN', 'EN']), ('percent after number', [['EN', 'ET', 'ET', 'L'], 'R'], ['EN', 'EN', 'EN', 'L']), ('NSM chain after R', [['R', 'NSM', 'NSM', 'EN'], 'L'], ['R', 'R', 'R', 'EN']), ('control layout', [['ES', 'NSM', 'R', 'AL'], 'L'], ['ON', 'ON', 'R', 'R']), ('control layout', [['LRI', 'AL', 'ES', 'LRI'], 'R'], ['LRI', 'R', 'ON', 'LRI'])], [('regression: European number context start', [['EN', 'AL', 'ES', 'R', 'LRI'], 'L'], ['L', 'R', 'ON', 'R', 'LRI']), ('regression: European number context start', [['EN', 'NSM', 'R'], 'L'], ['L', 'L', 'R']), ('partial-repair probe', [['CS', 'NSM', 'EN', 'AN', 'ET', 'ON'], 'R'], ['ON', 'ON', 'EN', 'AN', 'ON', 'ON']), ('partial-repair probe', [['ET', 'EN', 'ON', 'PDI', 'CS', 'PDI', 'ES'], 'R'], ['EN', 'EN', 'ON', 'PDI', 'ON', 'PDI', 'ON']), ('percent after number', [['EN', 'ET', 'ET', 'L'], 'R'], ['EN', 'EN', 'EN', 'L']), ('NSM chain after R', [['R', 'NSM', 'NSM', 'EN'], 'L'], ['R', 'R', 'R', 'EN']), ('control layout', [['WS', 'R', 'L', 'CS', 'AL', 'EN', 'AL', 'LRI', 'EN'], 'R'], ['WS', 'R', 'L', 'ON', 'R', 'AN', 'R', 'LRI', 'AN']), ('control layout', [['CS', 'R'], 'L'], ['ON', 'R'])], [('regression: European number context start', [['ES', 'EN'], 'L'], ['ON', 'L']), ('regression: European number context start', [['WS', 'EN', 'AL', 'CS', 'NSM', 'WS', 'EN'], 'L'], ['WS', 'L', 'R', 'ON', 'ON', 'WS', 'AN']), ('partial-repair probe', [['EN', 'L', 'CS', 'EN'], 'R'], ['EN', 'L', 'ON', 'L']), ('partial-repair probe', [['AN', 'PDI', 'EN', 'CS', 'R', 'NSM', 'AN', 'ET'], 'R'], ['AN', 'PDI', 'EN', 'ON', 'R', 'R', 'AN', 'ON']), ('NSM chain after R', [['R', 'NSM', 'NSM', 'EN'], 'L'], ['R', 'R', 'R', 'EN']), ('NSM after isolate initiator', [['LRI', 'NSM', 'L', 'PDI'], 'R'], ['LRI', 'ON', 'L', 'PDI']), ('control layout', [['LRI', 'AN', 'L', 'AL', 'ON'], 'R'], ['LRI', 'AN', 'L', 'R', 'ON']), ('control layout', [['R', 'NSM', 'AN', 'CS', 'ET', 'ET', 'LRI', 'NSM', 'L', 'EN', 'R'], 'R'], ['R', 'R', 'AN', 'ON', 'ON', 'ON', 'LRI', 'ON', 'L', 'L', 'R'])]]
for label, args, expected in fixtures[N - 1]:
    check(label, solve(args), expected)
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
regression: European number context start['ON', 'EN']['ON', 'L']Failed
regression: European number context start['EN', 'EN']['L', 'L']Failed
partial-repair probe['ON', 'ON', 'ON', 'ON', 'EN', 'EN', 'EN', 'LRI', 'ON', 'PDI', 'EN']['ON', 'ON', 'ON', 'ON', 'EN', 'EN', 'EN', 'LRI', 'ON', 'PDI', 'EN']Passed
partial-repair probe['ON', 'ON', 'ON', 'ON', 'EN', 'EN', 'EN']['ON', 'ON', 'ON', 'ON', 'EN', 'EN', 'EN']Passed
NSM after isolate initiator['LRI', 'ON', 'L', 'PDI']['LRI', 'ON', 'L', 'PDI']Passed
Arabic number context['R', 'AN', 'AN', 'AN']['R', 'AN', 'AN', 'AN']Passed
control layout['LRI', 'WS', 'ON']['LRI', 'WS', 'ON']Passed
control layout['AN', 'R', 'L', 'L', 'L', 'R', 'WS', 'ON']['AN', 'R', 'L', 'L', 'L', 'R', 'WS', 'ON']Passed

SHA-256 / 11fa11c9274791684ee2a29a5184fdf2bafabf1ecda50f1931803e78690f429c

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(x):
    types, sos = x
    t = list(types)
    n = len(t)
    prev = sos
    for i in range(n):
        if t[i] == 'NSM':
            t[i] = 'ON' if prev in ('LRI', 'RLI', 'FSI', 'PDI') else prev
        prev = t[i]
    last_strong = 'L'
    for i in range(n):
        if t[i] in ('L', 'R', 'AL'):
            last_strong = t[i]
        elif t[i] == 'EN' and last_strong == 'AL':
            t[i] = 'AN'
    t = ['R' if c == 'AL' else c for c in t]
    for i in range(1, n - 1):
        if t[i] == 'ES' and t[i - 1] == 'EN' and t[i + 1] == 'EN':
            t[i] = 'EN'
        elif t[i] == 'CS' and t[i - 1] == t[i + 1] and t[i - 1] in ('EN', 'AN'):
            t[i] = t[i - 1]
    i = 0
    while i < n:
        if t[i] == 'ET':
            j = i
            while j < n and t[j] == 'ET':
                j += 1
            if (i > 0 and t[i - 1] == 'EN') or (j < n and t[j] == 'EN'):
                for k in range(i, j):
                    t[k] = 'EN'
            i = j
        else:
            i += 1
    t = ['ON' if c in ('ES', 'ET', 'CS') else c for c in t]
    strong = 'L'
    for i in range(n):
        if t[i] in ('L', 'R'):
            strong = t[i]
        elif t[i] == 'EN' and strong == 'L':
            t[i] = 'L'
    return t
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: European number context start', [['ON', 'EN'], 'L'], ['ON', 'L']), ('regression: European number context start', [['EN', 'NSM'], 'L'], ['L', 'L']), ('partial-repair probe', [['ES', 'ON', 'ET', 'CS', 'EN', 'EN', 'NSM', 'LRI', 'CS', 'PDI', 'EN'], 'R'], ['ON', 'ON', 'ON', 'ON', 'EN', 'EN', 'EN', 'LRI', 'ON', 'PDI', 'EN']), ('partial-repair probe', [['ET', 'ES', 'NSM', 'CS', 'EN', 'CS', 'EN'], 'R'], ['ON', 'ON', 'ON', 'ON', 'EN', 'EN', 'EN']), ('NSM after isolate initiator', [['LRI', 'NSM', 'L', 'PDI'], 'R'], ['LRI', 'ON', 'L', 'PDI']), ('Arabic number context', [['AL', 'EN', 'CS', 'EN'], 'L'], ['R', 'AN', 'AN', 'AN']), ('control layout', [['LRI', 'WS', 'ET'], 'R'], ['LRI', 'WS', 'ON']), ('control layout', [['AN', 'AL', 'L', 'EN', 'EN', 'AL', 'WS', 'ET'], 'R'], ['AN', 'R', 'L', 'L', 'L', 'R', 'WS', 'ON'])], [('regression: European number context start', [['EN', 'ON', 'R', 'AL', 'ES', 'AL'], 'L'], ['L', 'ON', 'R', 'R', 'ON', 'R']), ('regression: European number context start', [['LRI', 'EN', 'R', 'NSM', 'R', 'L', 'ON', 'EN'], 'L'], ['LRI', 'L', 'R', 'R', 'R', 'L', 'ON', 'L']), ('partial-repair probe', [['AN', 'EN'], 'R'], ['AN', 'EN']), ('partial-repair probe', [['CS', 'EN', 'EN'], 'R'], ['ON', 'EN', 'EN']), ('Arabic number context', [['AL', 'EN', 'CS', 'EN'], 'L'], ['R', 'AN', 'AN', 'AN']), ('NSM chain after R', [['R', 'NSM', 'NSM', 'EN'], 'L'], ['R', 'R', 'R', 'EN']), ('control layout', [['ES', 'NSM', 'AL'], 'R'], ['ON', 'ON', 'R']), ('control layout', [['CS', 'R', 'AN', 'L', 'NSM', 'EN', 'EN', 'AN', 'ET', 'AL', 'WS'], 'R'], ['ON', 'R', 'AN', 'L', 'L', 'L', 'L', 'AN', 'ON', 'R', 'WS'])], [('regression: European number context start', [['ES', 'EN'], 'L'], ['ON', 'L']), ('regression: European number context start', [['EN', 'AN', 'LRI', 'ES', 'ON', 'L', 'EN', 'AL', 'R'], 'L'], ['L', 'AN', 'LRI', 'ON', 'ON', 'L', 'L', 'R', 'R']), ('partial-repair probe', [['CS', 'EN', 'PDI', 'ES', 'ET', 'R'], 'R'], ['ON', 'EN', 'PDI', 'ON', 'ON', 'R']), ('partial-repair probe', [['AN', 'AN', 'CS', 'EN', 'ON', 'EN', 'EN'], 'R'], ['AN', 'AN', 'ON', 'EN', 'ON', 'EN', 'EN']), ('percent after number', [['EN', 'ET', 'ET', 'L'], 'R'], ['EN', 'EN', 'EN', 'L']), ('NSM chain after R', [['R', 'NSM', 'NSM', 'EN'], 'L'], ['R', 'R', 'R', 'EN']), ('control layout', [['ES', 'NSM', 'R', 'AL'], 'L'], ['ON', 'ON', 'R', 'R']), ('control layout', [['LRI', 'AL', 'ES', 'LRI'], 'R'], ['LRI', 'R', 'ON', 'LRI'])], [('regression: European number context start', [['EN', 'AL', 'ES', 'R', 'LRI'], 'L'], ['L', 'R', 'ON', 'R', 'LRI']), ('regression: European number context start', [['EN', 'NSM', 'R'], 'L'], ['L', 'L', 'R']), ('partial-repair probe', [['CS', 'NSM', 'EN', 'AN', 'ET', 'ON'], 'R'], ['ON', 'ON', 'EN', 'AN', 'ON', 'ON']), ('partial-repair probe', [['ET', 'EN', 'ON', 'PDI', 'CS', 'PDI', 'ES'], 'R'], ['EN', 'EN', 'ON', 'PDI', 'ON', 'PDI', 'ON']), ('percent after number', [['EN', 'ET', 'ET', 'L'], 'R'], ['EN', 'EN', 'EN', 'L']), ('NSM chain after R', [['R', 'NSM', 'NSM', 'EN'], 'L'], ['R', 'R', 'R', 'EN']), ('control layout', [['WS', 'R', 'L', 'CS', 'AL', 'EN', 'AL', 'LRI', 'EN'], 'R'], ['WS', 'R', 'L', 'ON', 'R', 'AN', 'R', 'LRI', 'AN']), ('control layout', [['CS', 'R'], 'L'], ['ON', 'R'])], [('regression: European number context start', [['ES', 'EN'], 'L'], ['ON', 'L']), ('regression: European number context start', [['WS', 'EN', 'AL', 'CS', 'NSM', 'WS', 'EN'], 'L'], ['WS', 'L', 'R', 'ON', 'ON', 'WS', 'AN']), ('partial-repair probe', [['EN', 'L', 'CS', 'EN'], 'R'], ['EN', 'L', 'ON', 'L']), ('partial-repair probe', [['AN', 'PDI', 'EN', 'CS', 'R', 'NSM', 'AN', 'ET'], 'R'], ['AN', 'PDI', 'EN', 'ON', 'R', 'R', 'AN', 'ON']), ('NSM chain after R', [['R', 'NSM', 'NSM', 'EN'], 'L'], ['R', 'R', 'R', 'EN']), ('NSM after isolate initiator', [['LRI', 'NSM', 'L', 'PDI'], 'R'], ['LRI', 'ON', 'L', 'PDI']), ('control layout', [['LRI', 'AN', 'L', 'AL', 'ON'], 'R'], ['LRI', 'AN', 'L', 'R', 'ON']), ('control layout', [['R', 'NSM', 'AN', 'CS', 'ET', 'ET', 'LRI', 'NSM', 'L', 'EN', 'R'], 'R'], ['R', 'R', 'AN', 'ON', 'ON', 'ON', 'LRI', 'ON', 'L', 'L', 'R'])]]
for label, args, expected in fixtures[N - 1]:
    check(label, solve(args), expected)
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
regression: European number context start['ON', 'L']['ON', 'L']Passed
regression: European number context start['L', 'L']['L', 'L']Passed
partial-repair probe['ON', 'ON', 'ON', 'ON', 'L', 'L', 'L', 'LRI', 'ON', 'PDI', 'L']['ON', 'ON', 'ON', 'ON', 'EN', 'EN', 'EN', 'LRI', 'ON', 'PDI', 'EN']Failed
partial-repair probe['ON', 'ON', 'ON', 'ON', 'L', 'L', 'L']['ON', 'ON', 'ON', 'ON', 'EN', 'EN', 'EN']Failed
NSM after isolate initiator['LRI', 'ON', 'L', 'PDI']['LRI', 'ON', 'L', 'PDI']Passed
Arabic number context['R', 'AN', 'AN', 'AN']['R', 'AN', 'AN', 'AN']Passed
control layout['LRI', 'WS', 'ON']['LRI', 'WS', 'ON']Passed
control layout['AN', 'R', 'L', 'L', 'L', 'R', 'WS', 'ON']['AN', 'R', 'L', 'L', 'L', 'R', 'WS', 'ON']Passed

SHA-256 / 4c819ff6e5cdfbdb0d4b12a7f59da2caafa1b71c5bdbf64c4924c01f3ec5659c

3 / The verified repair

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

N = 1
observations = []
def solve(x):
    types, sos = x
    t = list(types)
    n = len(t)
    prev = sos
    for i in range(n):
        if t[i] == 'NSM':
            t[i] = 'ON' if prev in ('LRI', 'RLI', 'FSI', 'PDI') else prev
        prev = t[i]
    last_strong = sos
    for i in range(n):
        if t[i] in ('L', 'R', 'AL'):
            last_strong = t[i]
        elif t[i] == 'EN' and last_strong == 'AL':
            t[i] = 'AN'
    t = ['R' if c == 'AL' else c for c in t]
    for i in range(1, n - 1):
        if t[i] == 'ES' and t[i - 1] == 'EN' and t[i + 1] == 'EN':
            t[i] = 'EN'
        elif t[i] == 'CS' and t[i - 1] == t[i + 1] and t[i - 1] in ('EN', 'AN'):
            t[i] = t[i - 1]
    i = 0
    while i < n:
        if t[i] == 'ET':
            j = i
            while j < n and t[j] == 'ET':
                j += 1
            if (i > 0 and t[i - 1] == 'EN') or (j < n and t[j] == 'EN'):
                for k in range(i, j):
                    t[k] = 'EN'
            i = j
        else:
            i += 1
    t = ['ON' if c in ('ES', 'ET', 'CS') else c for c in t]
    strong = sos
    for i in range(n):
        if t[i] in ('L', 'R'):
            strong = t[i]
        elif t[i] == 'EN' and strong == 'L':
            t[i] = 'L'
    return t
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: European number context start', [['ON', 'EN'], 'L'], ['ON', 'L']), ('regression: European number context start', [['EN', 'NSM'], 'L'], ['L', 'L']), ('partial-repair probe', [['ES', 'ON', 'ET', 'CS', 'EN', 'EN', 'NSM', 'LRI', 'CS', 'PDI', 'EN'], 'R'], ['ON', 'ON', 'ON', 'ON', 'EN', 'EN', 'EN', 'LRI', 'ON', 'PDI', 'EN']), ('partial-repair probe', [['ET', 'ES', 'NSM', 'CS', 'EN', 'CS', 'EN'], 'R'], ['ON', 'ON', 'ON', 'ON', 'EN', 'EN', 'EN']), ('NSM after isolate initiator', [['LRI', 'NSM', 'L', 'PDI'], 'R'], ['LRI', 'ON', 'L', 'PDI']), ('Arabic number context', [['AL', 'EN', 'CS', 'EN'], 'L'], ['R', 'AN', 'AN', 'AN']), ('control layout', [['LRI', 'WS', 'ET'], 'R'], ['LRI', 'WS', 'ON']), ('control layout', [['AN', 'AL', 'L', 'EN', 'EN', 'AL', 'WS', 'ET'], 'R'], ['AN', 'R', 'L', 'L', 'L', 'R', 'WS', 'ON'])], [('regression: European number context start', [['EN', 'ON', 'R', 'AL', 'ES', 'AL'], 'L'], ['L', 'ON', 'R', 'R', 'ON', 'R']), ('regression: European number context start', [['LRI', 'EN', 'R', 'NSM', 'R', 'L', 'ON', 'EN'], 'L'], ['LRI', 'L', 'R', 'R', 'R', 'L', 'ON', 'L']), ('partial-repair probe', [['AN', 'EN'], 'R'], ['AN', 'EN']), ('partial-repair probe', [['CS', 'EN', 'EN'], 'R'], ['ON', 'EN', 'EN']), ('Arabic number context', [['AL', 'EN', 'CS', 'EN'], 'L'], ['R', 'AN', 'AN', 'AN']), ('NSM chain after R', [['R', 'NSM', 'NSM', 'EN'], 'L'], ['R', 'R', 'R', 'EN']), ('control layout', [['ES', 'NSM', 'AL'], 'R'], ['ON', 'ON', 'R']), ('control layout', [['CS', 'R', 'AN', 'L', 'NSM', 'EN', 'EN', 'AN', 'ET', 'AL', 'WS'], 'R'], ['ON', 'R', 'AN', 'L', 'L', 'L', 'L', 'AN', 'ON', 'R', 'WS'])], [('regression: European number context start', [['ES', 'EN'], 'L'], ['ON', 'L']), ('regression: European number context start', [['EN', 'AN', 'LRI', 'ES', 'ON', 'L', 'EN', 'AL', 'R'], 'L'], ['L', 'AN', 'LRI', 'ON', 'ON', 'L', 'L', 'R', 'R']), ('partial-repair probe', [['CS', 'EN', 'PDI', 'ES', 'ET', 'R'], 'R'], ['ON', 'EN', 'PDI', 'ON', 'ON', 'R']), ('partial-repair probe', [['AN', 'AN', 'CS', 'EN', 'ON', 'EN', 'EN'], 'R'], ['AN', 'AN', 'ON', 'EN', 'ON', 'EN', 'EN']), ('percent after number', [['EN', 'ET', 'ET', 'L'], 'R'], ['EN', 'EN', 'EN', 'L']), ('NSM chain after R', [['R', 'NSM', 'NSM', 'EN'], 'L'], ['R', 'R', 'R', 'EN']), ('control layout', [['ES', 'NSM', 'R', 'AL'], 'L'], ['ON', 'ON', 'R', 'R']), ('control layout', [['LRI', 'AL', 'ES', 'LRI'], 'R'], ['LRI', 'R', 'ON', 'LRI'])], [('regression: European number context start', [['EN', 'AL', 'ES', 'R', 'LRI'], 'L'], ['L', 'R', 'ON', 'R', 'LRI']), ('regression: European number context start', [['EN', 'NSM', 'R'], 'L'], ['L', 'L', 'R']), ('partial-repair probe', [['CS', 'NSM', 'EN', 'AN', 'ET', 'ON'], 'R'], ['ON', 'ON', 'EN', 'AN', 'ON', 'ON']), ('partial-repair probe', [['ET', 'EN', 'ON', 'PDI', 'CS', 'PDI', 'ES'], 'R'], ['EN', 'EN', 'ON', 'PDI', 'ON', 'PDI', 'ON']), ('percent after number', [['EN', 'ET', 'ET', 'L'], 'R'], ['EN', 'EN', 'EN', 'L']), ('NSM chain after R', [['R', 'NSM', 'NSM', 'EN'], 'L'], ['R', 'R', 'R', 'EN']), ('control layout', [['WS', 'R', 'L', 'CS', 'AL', 'EN', 'AL', 'LRI', 'EN'], 'R'], ['WS', 'R', 'L', 'ON', 'R', 'AN', 'R', 'LRI', 'AN']), ('control layout', [['CS', 'R'], 'L'], ['ON', 'R'])], [('regression: European number context start', [['ES', 'EN'], 'L'], ['ON', 'L']), ('regression: European number context start', [['WS', 'EN', 'AL', 'CS', 'NSM', 'WS', 'EN'], 'L'], ['WS', 'L', 'R', 'ON', 'ON', 'WS', 'AN']), ('partial-repair probe', [['EN', 'L', 'CS', 'EN'], 'R'], ['EN', 'L', 'ON', 'L']), ('partial-repair probe', [['AN', 'PDI', 'EN', 'CS', 'R', 'NSM', 'AN', 'ET'], 'R'], ['AN', 'PDI', 'EN', 'ON', 'R', 'R', 'AN', 'ON']), ('NSM chain after R', [['R', 'NSM', 'NSM', 'EN'], 'L'], ['R', 'R', 'R', 'EN']), ('NSM after isolate initiator', [['LRI', 'NSM', 'L', 'PDI'], 'R'], ['LRI', 'ON', 'L', 'PDI']), ('control layout', [['LRI', 'AN', 'L', 'AL', 'ON'], 'R'], ['LRI', 'AN', 'L', 'R', 'ON']), ('control layout', [['R', 'NSM', 'AN', 'CS', 'ET', 'ET', 'LRI', 'NSM', 'L', 'EN', 'R'], 'R'], ['R', 'R', 'AN', 'ON', 'ON', 'ON', 'LRI', 'ON', 'L', 'L', 'R'])]]
for label, args, expected in fixtures[N - 1]:
    check(label, solve(args), expected)
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
regression: European number context start['ON', 'L']['ON', 'L']Passed
regression: European number context start['L', 'L']['L', 'L']Passed
partial-repair probe['ON', 'ON', 'ON', 'ON', 'EN', 'EN', 'EN', 'LRI', 'ON', 'PDI', 'EN']['ON', 'ON', 'ON', 'ON', 'EN', 'EN', 'EN', 'LRI', 'ON', 'PDI', 'EN']Passed
partial-repair probe['ON', 'ON', 'ON', 'ON', 'EN', 'EN', 'EN']['ON', 'ON', 'ON', 'ON', 'EN', 'EN', 'EN']Passed
NSM after isolate initiator['LRI', 'ON', 'L', 'PDI']['LRI', 'ON', 'L', 'PDI']Passed
Arabic number context['R', 'AN', 'AN', 'AN']['R', 'AN', 'AN', 'AN']Passed
control layout['LRI', 'WS', 'ON']['LRI', 'WS', 'ON']Passed
control layout['AN', 'R', 'L', 'L', 'L', 'R', 'WS', 'ON']['AN', 'R', 'L', 'L', 'L', 'R', 'WS', 'ON']Passed

SHA-256 / 942cdbdbe6b395ef66ba7ecc56bee65edc6f44fda54711505d7d1ad57c83695e

Verification & scope

A deterministic toy bidi model over stipulated class labels and integer levels; it is inspired by, but does not claim conformance to, any published algorithm. 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 2026-09-29T14:49:53.537251+00:00.

Case digest / 2adbb395e521f6c0c876749ad9a486c91c43fa2a8597f155878f666a0f281b34