WI-151: emit IFSC slice checksums in the PAR2 test fixture - #143
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…-151) The synthesised PAR2 index only carried Main + FileDesc packets, so a fixture set had no per-slice checksums and rust_par2 reported every file as damaged. Emit IFSC (Input File Slice Checksum) packets too: per file, the File ID followed by (MD5[16] + CRC32[4]) for each slice, with the final partial slice zero-padded to the slice size exactly as PAR2 and rust_par2's verifier compute them. This is the first piece of the WI-151 deterministic PAR2 fixtures and is what the in-flight slice verifier (WI-144) will check decoded slices against. Two tests prove the checksums are byte-exact: an intact file verifies through the slice checksums, and a single corrupted slice is pinpointed by its block index (which only works if the per-slice MD5/CRC are correct). Full nzb-postproc suite stays green. RecoverySlice packets remain out of scope here (they need the encoder and only matter for repair fixtures, WI-146/148). Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01TpoFnScdkRq7qxQLQZe1we
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First piece of the WI-151 deterministic PAR2 damage fixtures (parity-in-flight initiative). Independent of the WI-143/#140 and WI-144/#141 branches.
What
The synthesised PAR2 index (
crates/nzb-postproc/tests/support/par2_fixture.rs) only carried Main + FileDesc packets, so fixtures had no per-slice checksums andrust_par2reported every file as damaged. This adds IFSC (Input File Slice Checksum) packets: per file, the File ID followed by(MD5[16] + CRC32[4])per slice, with the final partial slice zero-padded to the slice size — exactly as PAR2 andrust_par2's verifier compute them. Adds acrc32fastdev-dependency.This is what the in-flight slice verifier (WI-144, #141) will check decoded slices against.
Proof it's byte-exact (
tests/par2_slice_fixture.rs)rust_par2::verify(...).all_correct().damaged_block_indices == [1]after flipping a byte in slice 1, which only holds if the per-slice MD5/CRC32 are correct.Full nzb-postproc suite stays green (59 unit + existing fixture/deobfuscation tests unaffected);
fmt+clippy -D warningsclean.Out of scope (remaining WI-151, follow-ups)
🤖 Generated with Claude Code
https://claude.ai/code/session_01TpoFnScdkRq7qxQLQZe1we