Step 2b: package codec is rewritten without reflection or struct tags. A
strict Decoder accepts only the spec §58 profile, Unmarshal decodes,
re-encodes and compares, Peek reads the type tag and version, and Walk is a
bounded iterative helper for vectors and fuzzing. Every schema has its own
hand-written encoder and decoder that checks all CDDL rules before the
fields with their own error codes. github.com/fxamacker/cbor/v2 and
github.com/x448/float16 are gone; nothing replaces them. Valid objects
encode and decode exactly as before (1.34 million differential verdicts);
the invalid-input differences are documented in CHANGELOG and
traceability decision 12. A review found and fixed an access_policy check
that truncated to uint8.
Step 3: testdata gains vectors/cbor.json (generic and per-schema CBOR
vectors), vectors/mutations.json (the 55-case mutation corpus, replayable
offline), vectors/inspect_differential.json (1,825 fixed-seed mutations
with the Go verdict) and one inspect -json golden per fixture, all
regenerated byte-identically by genfixtures and documented in
testdata/README.md for second implementations.
Gate green with 90 s of fuzzing per target on all 15 targets; codec at
100 % coverage; pre-existing testdata byte-identical.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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