c527caccc5
Deterministic-seed fuzz coverage of the byte-decoding surface:
- secs2::decode on 2000 random buffers
- secs2::decode on every truncation of a real encoding + 500
one-byte flips of the full encoding
- hsms::Frame::decode on 1000 random payloads
- hsms::Header::decode on 2000 random 10-byte buffers
- secsi::Block::decode on 2000 random buffers
- secs2 encode/decode round-trip identity across a battery of every
Item factory (List, ASCII, Binary, Boolean, U1..U8, I1..I8, F4/F8,
nested List)
- oversize <A 3 length-bytes> length-prefix doesn't allocate GBs
- 64-level nested List round-trip doesn't blow the stack
Contract is binary: no crash, no UB. Each decoder is allowed to throw
or return whatever; we deliberately don't assert *what* result comes
back, only that control returns. Fixed PRNG seeds make any failure
reproducible from the CI log alone.
Closes #8 in the test-gap backlog.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>