FA-76646 / Email MIME structure / Open access
Collect the plain-text body to display: attachment before message · case 01
The text of an attached message is shown as part of the body.
ROOT CAUSE
The attachment before message decision evaluates `if t == 'message/rfc822': return walk(n['body']) if disp == 'attachment': return []` where the contract requires `if disp == 'attachment': return [] if t == 'message/rfc822': return walk(n['body'])`.
VERIFIED REPAIR
Use `if disp == 'attachment': return [] if t == 'message/rfc822': return walk(n['body'])` for the attachment before message decision and keep every other rule of the model unchanged.
Unsuccessful approach: Exempting text/plain from the attachment rule shows attached log files instead. The attempted `if disp == 'attachment' and t != 'text/plain': return [] if t == 'message/rfc822': return walk(n['body'])` still disagrees with a fixture.
Case contract
Returns the text/plain strings to display in order. Types compare case-insensitively. multipart/alternative yields the result of its last child that yields any text; other multiparts concatenate their children. Entities with an attachment disposition yield nothing. A message/rfc822 without attachment disposition yields its body; text/plain yields its text; everything else yields nothing.
Why this case matters
Text extraction powers previews, replies and search; wrong choices quote attachments or skip the real body.
1 / The failure
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(tree):
def walk(n):
t = n['type'].lower()
disp = (n.get('disp') or 'inline').lower()
if t == 'multipart/alternative':
for child in reversed(n['parts']):
got = walk(child)
if got:
return got
return []
if t.startswith('multipart/'):
out = []
for child in n['parts']:
out.extend(walk(child))
return out
if t == 'message/rfc822':
return walk(n['body'])
if disp == 'attachment':
return []
if t == 'text/plain':
return [n['text']]
return []
return walk(tree)
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_CASES = {1: [('richer alternative holds text', ({'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'A1'}, {'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'B1'}, {'type': 'image/png'}]}]},), ['B1']), ('html last alternative', ({'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'plain 1'}, {'type': 'text/html'}]},), ['plain 1']), ('attached message and log', ({'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'hi'}, {'type': 'message/rfc822', 'disp': 'attachment', 'body': {'type': 'text/plain', 'text': 'inner'}}, {'type': 'text/plain', 'disp': 'attachment', 'text': 'log 1'}]},), ['hi']), ('inline forwarded alternative', ({'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'x'}, {'type': 'message/rfc822', 'body': {'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'fw1'}, {'type': 'text/html'}]}}]},), ['x', 'fw1']), ('mixed-case types', ({'type': 'MULTIPART/Mixed', 'parts': [{'type': 'Text/Plain', 'text': 't1'}, {'type': 'TEXT/PLAIN', 'text': 'u'}]},), ['t1', 'u']), ('no text at all', ({'type': 'multipart/mixed', 'parts': [{'type': 'image/png'}, {'type': 'application/pdf'}]},), [])], 2: [('richer alternative holds text', ({'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'A2'}, {'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'B2'}, {'type': 'image/png'}]}]},), ['B2']), ('html last alternative', ({'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'plain 2'}, {'type': 'text/html'}]},), ['plain 2']), ('attached message and log', ({'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'hi'}, {'type': 'message/rfc822', 'disp': 'attachment', 'body': {'type': 'text/plain', 'text': 'inner'}}, {'type': 'text/plain', 'disp': 'attachment', 'text': 'log 2'}]},), ['hi']), ('inline forwarded alternative', ({'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'x'}, {'type': 'message/rfc822', 'body': {'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'fw2'}, {'type': 'text/html'}]}}]},), ['x', 'fw2']), ('mixed-case types', ({'type': 'MULTIPART/Mixed', 'parts': [{'type': 'Text/Plain', 'text': 't2'}, {'type': 'TEXT/PLAIN', 'text': 'u'}]},), ['t2', 'u']), ('no text at all', ({'type': 'multipart/mixed', 'parts': [{'type': 'image/png'}, {'type': 'application/pdf'}]},), [])], 3: [('richer alternative holds text', ({'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'A3'}, {'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'B3'}, {'type': 'image/png'}]}]},), ['B3']), ('html last alternative', ({'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'plain 3'}, {'type': 'text/html'}]},), ['plain 3']), ('attached message and log', ({'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'hi'}, {'type': 'message/rfc822', 'disp': 'attachment', 'body': {'type': 'text/plain', 'text': 'inner'}}, {'type': 'text/plain', 'disp': 'attachment', 'text': 'log 3'}]},), ['hi']), ('inline forwarded alternative', ({'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'x'}, {'type': 'message/rfc822', 'body': {'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'fw3'}, {'type': 'text/html'}]}}]},), ['x', 'fw3']), ('mixed-case types', ({'type': 'MULTIPART/Mixed', 'parts': [{'type': 'Text/Plain', 'text': 't3'}, {'type': 'TEXT/PLAIN', 'text': 'u'}]},), ['t3', 'u']), ('no text at all', ({'type': 'multipart/mixed', 'parts': [{'type': 'image/png'}, {'type': 'application/pdf'}]},), [])], 4: [('richer alternative holds text', ({'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'A4'}, {'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'B4'}, {'type': 'image/png'}]}]},), ['B4']), ('html last alternative', ({'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'plain 4'}, {'type': 'text/html'}]},), ['plain 4']), ('attached message and log', ({'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'hi'}, {'type': 'message/rfc822', 'disp': 'attachment', 'body': {'type': 'text/plain', 'text': 'inner'}}, {'type': 'text/plain', 'disp': 'attachment', 'text': 'log 4'}]},), ['hi']), ('inline forwarded alternative', ({'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'x'}, {'type': 'message/rfc822', 'body': {'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'fw4'}, {'type': 'text/html'}]}}]},), ['x', 'fw4']), ('mixed-case types', ({'type': 'MULTIPART/Mixed', 'parts': [{'type': 'Text/Plain', 'text': 't4'}, {'type': 'TEXT/PLAIN', 'text': 'u'}]},), ['t4', 'u']), ('no text at all', ({'type': 'multipart/mixed', 'parts': [{'type': 'image/png'}, {'type': 'application/pdf'}]},), [])], 5: [('richer alternative holds text', ({'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'A5'}, {'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'B5'}, {'type': 'image/png'}]}]},), ['B5']), ('html last alternative', ({'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'plain 5'}, {'type': 'text/html'}]},), ['plain 5']), ('attached message and log', ({'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'hi'}, {'type': 'message/rfc822', 'disp': 'attachment', 'body': {'type': 'text/plain', 'text': 'inner'}}, {'type': 'text/plain', 'disp': 'attachment', 'text': 'log 5'}]},), ['hi']), ('inline forwarded alternative', ({'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'x'}, {'type': 'message/rfc822', 'body': {'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'fw5'}, {'type': 'text/html'}]}}]},), ['x', 'fw5']), ('mixed-case types', ({'type': 'MULTIPART/Mixed', 'parts': [{'type': 'Text/Plain', 'text': 't5'}, {'type': 'TEXT/PLAIN', 'text': 'u'}]},), ['t5', 'u']), ('no text at all', ({'type': 'multipart/mixed', 'parts': [{'type': 'image/png'}, {'type': 'application/pdf'}]},), [])]}
for _label, _args, _expected in _CASES[N]:
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 fixture | Actual | Expected | Outcome |
|---|---|---|---|
| richer alternative holds text | ['B1'] | ['B1'] | Passed |
| html last alternative | ['plain 1'] | ['plain 1'] | Passed |
| attached message and log | ['hi', 'inner'] | ['hi'] | Failed |
| inline forwarded alternative | ['x', 'fw1'] | ['x', 'fw1'] | Passed |
| mixed-case types | ['t1', 'u'] | ['t1', 'u'] | Passed |
| no text at all | [] | [] | Passed |
SHA-256 / 991e16642bd89be52d1dc4b82881321f510d0e722b95300d189dc75697106f47
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(tree):
def walk(n):
t = n['type'].lower()
disp = (n.get('disp') or 'inline').lower()
if t == 'multipart/alternative':
for child in reversed(n['parts']):
got = walk(child)
if got:
return got
return []
if t.startswith('multipart/'):
out = []
for child in n['parts']:
out.extend(walk(child))
return out
if disp == 'attachment' and t != 'text/plain':
return []
if t == 'message/rfc822':
return walk(n['body'])
if t == 'text/plain':
return [n['text']]
return []
return walk(tree)
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_CASES = {1: [('richer alternative holds text', ({'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'A1'}, {'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'B1'}, {'type': 'image/png'}]}]},), ['B1']), ('html last alternative', ({'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'plain 1'}, {'type': 'text/html'}]},), ['plain 1']), ('attached message and log', ({'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'hi'}, {'type': 'message/rfc822', 'disp': 'attachment', 'body': {'type': 'text/plain', 'text': 'inner'}}, {'type': 'text/plain', 'disp': 'attachment', 'text': 'log 1'}]},), ['hi']), ('inline forwarded alternative', ({'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'x'}, {'type': 'message/rfc822', 'body': {'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'fw1'}, {'type': 'text/html'}]}}]},), ['x', 'fw1']), ('mixed-case types', ({'type': 'MULTIPART/Mixed', 'parts': [{'type': 'Text/Plain', 'text': 't1'}, {'type': 'TEXT/PLAIN', 'text': 'u'}]},), ['t1', 'u']), ('no text at all', ({'type': 'multipart/mixed', 'parts': [{'type': 'image/png'}, {'type': 'application/pdf'}]},), [])], 2: [('richer alternative holds text', ({'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'A2'}, {'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'B2'}, {'type': 'image/png'}]}]},), ['B2']), ('html last alternative', ({'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'plain 2'}, {'type': 'text/html'}]},), ['plain 2']), ('attached message and log', ({'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'hi'}, {'type': 'message/rfc822', 'disp': 'attachment', 'body': {'type': 'text/plain', 'text': 'inner'}}, {'type': 'text/plain', 'disp': 'attachment', 'text': 'log 2'}]},), ['hi']), ('inline forwarded alternative', ({'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'x'}, {'type': 'message/rfc822', 'body': {'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'fw2'}, {'type': 'text/html'}]}}]},), ['x', 'fw2']), ('mixed-case types', ({'type': 'MULTIPART/Mixed', 'parts': [{'type': 'Text/Plain', 'text': 't2'}, {'type': 'TEXT/PLAIN', 'text': 'u'}]},), ['t2', 'u']), ('no text at all', ({'type': 'multipart/mixed', 'parts': [{'type': 'image/png'}, {'type': 'application/pdf'}]},), [])], 3: [('richer alternative holds text', ({'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'A3'}, {'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'B3'}, {'type': 'image/png'}]}]},), ['B3']), ('html last alternative', ({'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'plain 3'}, {'type': 'text/html'}]},), ['plain 3']), ('attached message and log', ({'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'hi'}, {'type': 'message/rfc822', 'disp': 'attachment', 'body': {'type': 'text/plain', 'text': 'inner'}}, {'type': 'text/plain', 'disp': 'attachment', 'text': 'log 3'}]},), ['hi']), ('inline forwarded alternative', ({'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'x'}, {'type': 'message/rfc822', 'body': {'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'fw3'}, {'type': 'text/html'}]}}]},), ['x', 'fw3']), ('mixed-case types', ({'type': 'MULTIPART/Mixed', 'parts': [{'type': 'Text/Plain', 'text': 't3'}, {'type': 'TEXT/PLAIN', 'text': 'u'}]},), ['t3', 'u']), ('no text at all', ({'type': 'multipart/mixed', 'parts': [{'type': 'image/png'}, {'type': 'application/pdf'}]},), [])], 4: [('richer alternative holds text', ({'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'A4'}, {'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'B4'}, {'type': 'image/png'}]}]},), ['B4']), ('html last alternative', ({'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'plain 4'}, {'type': 'text/html'}]},), ['plain 4']), ('attached message and log', ({'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'hi'}, {'type': 'message/rfc822', 'disp': 'attachment', 'body': {'type': 'text/plain', 'text': 'inner'}}, {'type': 'text/plain', 'disp': 'attachment', 'text': 'log 4'}]},), ['hi']), ('inline forwarded alternative', ({'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'x'}, {'type': 'message/rfc822', 'body': {'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'fw4'}, {'type': 'text/html'}]}}]},), ['x', 'fw4']), ('mixed-case types', ({'type': 'MULTIPART/Mixed', 'parts': [{'type': 'Text/Plain', 'text': 't4'}, {'type': 'TEXT/PLAIN', 'text': 'u'}]},), ['t4', 'u']), ('no text at all', ({'type': 'multipart/mixed', 'parts': [{'type': 'image/png'}, {'type': 'application/pdf'}]},), [])], 5: [('richer alternative holds text', ({'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'A5'}, {'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'B5'}, {'type': 'image/png'}]}]},), ['B5']), ('html last alternative', ({'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'plain 5'}, {'type': 'text/html'}]},), ['plain 5']), ('attached message and log', ({'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'hi'}, {'type': 'message/rfc822', 'disp': 'attachment', 'body': {'type': 'text/plain', 'text': 'inner'}}, {'type': 'text/plain', 'disp': 'attachment', 'text': 'log 5'}]},), ['hi']), ('inline forwarded alternative', ({'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'x'}, {'type': 'message/rfc822', 'body': {'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'fw5'}, {'type': 'text/html'}]}}]},), ['x', 'fw5']), ('mixed-case types', ({'type': 'MULTIPART/Mixed', 'parts': [{'type': 'Text/Plain', 'text': 't5'}, {'type': 'TEXT/PLAIN', 'text': 'u'}]},), ['t5', 'u']), ('no text at all', ({'type': 'multipart/mixed', 'parts': [{'type': 'image/png'}, {'type': 'application/pdf'}]},), [])]}
for _label, _args, _expected in _CASES[N]:
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 fixture | Actual | Expected | Outcome |
|---|---|---|---|
| richer alternative holds text | ['B1'] | ['B1'] | Passed |
| html last alternative | ['plain 1'] | ['plain 1'] | Passed |
| attached message and log | ['hi', 'log 1'] | ['hi'] | Failed |
| inline forwarded alternative | ['x', 'fw1'] | ['x', 'fw1'] | Passed |
| mixed-case types | ['t1', 'u'] | ['t1', 'u'] | Passed |
| no text at all | [] | [] | Passed |
SHA-256 / 7f114b027a8e8215f5c25eb4f9df0d44c7b17c0aa2e4cb2f16b59853dfc17d21
3 / The verified repair
Exit 0"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(tree):
def walk(n):
t = n['type'].lower()
disp = (n.get('disp') or 'inline').lower()
if t == 'multipart/alternative':
for child in reversed(n['parts']):
got = walk(child)
if got:
return got
return []
if t.startswith('multipart/'):
out = []
for child in n['parts']:
out.extend(walk(child))
return out
if disp == 'attachment':
return []
if t == 'message/rfc822':
return walk(n['body'])
if t == 'text/plain':
return [n['text']]
return []
return walk(tree)
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_CASES = {1: [('richer alternative holds text', ({'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'A1'}, {'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'B1'}, {'type': 'image/png'}]}]},), ['B1']), ('html last alternative', ({'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'plain 1'}, {'type': 'text/html'}]},), ['plain 1']), ('attached message and log', ({'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'hi'}, {'type': 'message/rfc822', 'disp': 'attachment', 'body': {'type': 'text/plain', 'text': 'inner'}}, {'type': 'text/plain', 'disp': 'attachment', 'text': 'log 1'}]},), ['hi']), ('inline forwarded alternative', ({'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'x'}, {'type': 'message/rfc822', 'body': {'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'fw1'}, {'type': 'text/html'}]}}]},), ['x', 'fw1']), ('mixed-case types', ({'type': 'MULTIPART/Mixed', 'parts': [{'type': 'Text/Plain', 'text': 't1'}, {'type': 'TEXT/PLAIN', 'text': 'u'}]},), ['t1', 'u']), ('no text at all', ({'type': 'multipart/mixed', 'parts': [{'type': 'image/png'}, {'type': 'application/pdf'}]},), [])], 2: [('richer alternative holds text', ({'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'A2'}, {'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'B2'}, {'type': 'image/png'}]}]},), ['B2']), ('html last alternative', ({'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'plain 2'}, {'type': 'text/html'}]},), ['plain 2']), ('attached message and log', ({'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'hi'}, {'type': 'message/rfc822', 'disp': 'attachment', 'body': {'type': 'text/plain', 'text': 'inner'}}, {'type': 'text/plain', 'disp': 'attachment', 'text': 'log 2'}]},), ['hi']), ('inline forwarded alternative', ({'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'x'}, {'type': 'message/rfc822', 'body': {'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'fw2'}, {'type': 'text/html'}]}}]},), ['x', 'fw2']), ('mixed-case types', ({'type': 'MULTIPART/Mixed', 'parts': [{'type': 'Text/Plain', 'text': 't2'}, {'type': 'TEXT/PLAIN', 'text': 'u'}]},), ['t2', 'u']), ('no text at all', ({'type': 'multipart/mixed', 'parts': [{'type': 'image/png'}, {'type': 'application/pdf'}]},), [])], 3: [('richer alternative holds text', ({'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'A3'}, {'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'B3'}, {'type': 'image/png'}]}]},), ['B3']), ('html last alternative', ({'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'plain 3'}, {'type': 'text/html'}]},), ['plain 3']), ('attached message and log', ({'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'hi'}, {'type': 'message/rfc822', 'disp': 'attachment', 'body': {'type': 'text/plain', 'text': 'inner'}}, {'type': 'text/plain', 'disp': 'attachment', 'text': 'log 3'}]},), ['hi']), ('inline forwarded alternative', ({'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'x'}, {'type': 'message/rfc822', 'body': {'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'fw3'}, {'type': 'text/html'}]}}]},), ['x', 'fw3']), ('mixed-case types', ({'type': 'MULTIPART/Mixed', 'parts': [{'type': 'Text/Plain', 'text': 't3'}, {'type': 'TEXT/PLAIN', 'text': 'u'}]},), ['t3', 'u']), ('no text at all', ({'type': 'multipart/mixed', 'parts': [{'type': 'image/png'}, {'type': 'application/pdf'}]},), [])], 4: [('richer alternative holds text', ({'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'A4'}, {'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'B4'}, {'type': 'image/png'}]}]},), ['B4']), ('html last alternative', ({'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'plain 4'}, {'type': 'text/html'}]},), ['plain 4']), ('attached message and log', ({'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'hi'}, {'type': 'message/rfc822', 'disp': 'attachment', 'body': {'type': 'text/plain', 'text': 'inner'}}, {'type': 'text/plain', 'disp': 'attachment', 'text': 'log 4'}]},), ['hi']), ('inline forwarded alternative', ({'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'x'}, {'type': 'message/rfc822', 'body': {'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'fw4'}, {'type': 'text/html'}]}}]},), ['x', 'fw4']), ('mixed-case types', ({'type': 'MULTIPART/Mixed', 'parts': [{'type': 'Text/Plain', 'text': 't4'}, {'type': 'TEXT/PLAIN', 'text': 'u'}]},), ['t4', 'u']), ('no text at all', ({'type': 'multipart/mixed', 'parts': [{'type': 'image/png'}, {'type': 'application/pdf'}]},), [])], 5: [('richer alternative holds text', ({'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'A5'}, {'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'B5'}, {'type': 'image/png'}]}]},), ['B5']), ('html last alternative', ({'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'plain 5'}, {'type': 'text/html'}]},), ['plain 5']), ('attached message and log', ({'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'hi'}, {'type': 'message/rfc822', 'disp': 'attachment', 'body': {'type': 'text/plain', 'text': 'inner'}}, {'type': 'text/plain', 'disp': 'attachment', 'text': 'log 5'}]},), ['hi']), ('inline forwarded alternative', ({'type': 'multipart/mixed', 'parts': [{'type': 'text/plain', 'text': 'x'}, {'type': 'message/rfc822', 'body': {'type': 'multipart/alternative', 'parts': [{'type': 'text/plain', 'text': 'fw5'}, {'type': 'text/html'}]}}]},), ['x', 'fw5']), ('mixed-case types', ({'type': 'MULTIPART/Mixed', 'parts': [{'type': 'Text/Plain', 'text': 't5'}, {'type': 'TEXT/PLAIN', 'text': 'u'}]},), ['t5', 'u']), ('no text at all', ({'type': 'multipart/mixed', 'parts': [{'type': 'image/png'}, {'type': 'application/pdf'}]},), [])]}
for _label, _args, _expected in _CASES[N]:
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 fixture | Actual | Expected | Outcome |
|---|---|---|---|
| richer alternative holds text | ['B1'] | ['B1'] | Passed |
| html last alternative | ['plain 1'] | ['plain 1'] | Passed |
| attached message and log | ['hi'] | ['hi'] | Passed |
| inline forwarded alternative | ['x', 'fw1'] | ['x', 'fw1'] | Passed |
| mixed-case types | ['t1', 'u'] | ['t1', 'u'] | Passed |
| no text at all | [] | [] | Passed |
SHA-256 / f1be4396ec22927d1b8a710afb41affde67f9ec6d7239ad0d04e2efbb6c09514
Verification & scope
Stipulated offline model over pre-parsed MIME dictionaries; not a conforming MIME parser, generator or mail client. 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 2026-09-29T14:49:18.097366+00:00.
Case digest / 224e0f68b1d0bba99d3ef0bad863717ebed682aa525c244a8c712443c70fe954