Audit correction. The manifest test was documented -- in its own doc comment, in
DECISIONS.md, and in P3's commit message -- as "exhaustive single-byte
perturbation". It tried three XOR deltas per byte. The claim was false as
executed, and the "guard is total" conclusion leaned on it.
Both tests now do what their names say:
every_single_byte_replacement_of_a_manifest_is_rejected -- each byte, each of
the 255 other values. 0.15s.
compression_none_rejects_a_non_zero_parameter_byte -- every one of the 255
non-zero parameter bytes, plus a round-trip of all 256 values through Zstd and
Reserved, so the strictness is shown to be confined to None.
And the totality claim is re-seated where it belongs: on the argument, not on a
finite test. manifest_id is derived from the body, so a body edit fails the id
check and an id edit fails the derivation; encode_body sorts and deduplicates
every vector, so an out-of-order or duplicated encoding cannot round-trip. The
test is evidence for that argument over ONE constructed manifest, and is blind
to multi-byte perturbations entirely. Both the doc comment and DECISIONS.md now
say so.
Worth recording: restoring the leniency fails the codec test and the index test,
and leaves the manifest test GREEN -- the guard rejects those bytes whatever the
sub-codec does. That is not a weak test. It is the asymmetry that hid the bug,
and it locks the guard rather than the codec. A suite where every test fails on
every mutation would be telling us less.
No codec or wire-format change; the strict branch was already correct.
Gate: fmt clean, clippy 0, 30 targets / 1012 passed / 0 failed, docs 0 under
-D warnings, conformance 8/8, zero golden churn.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Levi Neuwirth
09a7f62802