Adversarial review of the new multipart keying turned up collisions where
two different provider requests computed the same replay key, which is the
dangerous failure for a replay harness: the second request silently gets the
first one's response instead of missing loudly.
- a part counts as an upload when it has a filename or declares its own
content type, and the declared content type joins the identity, so two
uploads of the same bytes under the same field no longer collapse
- the uploaded parts contribute a JSON list of [field, filename, type]
triples instead of a "field:filename" string, so a separator inside a
filename can no longer impersonate a field boundary
- repeated field names get a "name[n]" suffix with a literal "[" doubled
first, so a repeated field and a literally indexed one stay distinct
- a field value that is not UTF-8 is stored as a base64 sha256 digest;
base64 rather than hex because the canonicalizer rewrites 64-character
hex runs to <sha256> and folded every binary value onto one key
- a field whose name reads as a credential is stored as <secret>. This
stays key-preserving because the key is recomputed from the stored
request rather than saved beside it, so the live request carrying the
real value still matches its redacted fixture
- the uploaded byte length leaves the key. The canonicalizer absorbs
timestamp and id drift inside a file, and that drift moves the count,
so keeping it there made re-records miss
Also stops a lookalike parameter such as "xboundary=" from being read as
the multipart boundary, and gives the OpenAI batch backend model a single
constant instead of three copies of the literal.
BUNDLE_FORMAT_VERSION goes to 3 because all of this moves recorded keys.
A bundle recorded under the old rules now fails naming both versions
instead of missing on every call.
Replay previously matched interactions by transport verb and path in
recorded order, so a request whose body drifted from the recording
silently replayed the stale response, and reordering two independent
calls broke replay even though both were recorded. Match keys are now
canonical: fixture_canonical.py strips volatile headers and credential
fields, replaces unique markers, generated ids, uuids, and timestamps
with fixed placeholders, sorts object keys, and hashes what remains, so
a key is stable across runs and machines while any real content drift
is a hard ReplayMiss naming the computed key, the closest recorded key
with its file, and a content diff, with no fallthrough to a live call.
Matching is order-independent across distinct keys and FIFO within one
key. Recording now also redacts credential body and form fields (not
just auth headers) so provider keys never land in bundles.
Resolves LIT-5741
