Migration plan: sdlc/#417/audit.md (root: #417). PRs 4-5. Check in a tiny fixture chunk; assert serialize.write_chunk output byte-identical; write docs/chunk-bin-format.md as the single normative spec. Add requirements-dev.txt with pytest; drop per-file main/sys.path runners. Verify: corrupting one header byte fails the test. Addresses X1, T1. Safety net for the refactor PRs.
Migration plan: sdlc/#417/audit.md (root: #417). PRs 4-5. Check in a tiny fixture chunk; assert serialize.write_chunk output byte-identical; write docs/chunk-bin-format.md as the single normative spec. Add requirements-dev.txt with pytest; drop per-file main/sys.path runners. Verify: corrupting one header byte fails the test. Addresses X1, T1. Safety net for the refactor PRs.