Iter 39. Defends the wire-format CRC contract from silent polynomial
substitution. ADR-119 §2.4 specifies CRC-32/ISO-HDLC (same as Ethernet
and zlib), NOT CRC-32C (Castagnoli) or any other variant. Two BFLD
implementations that disagree on the polynomial treat every frame
from the other as corrupt.
Added (in tests/crc32_polynomial.rs):
- 7 named tests using canonical CRC vectors from the reveng catalogue
(https://reveng.sourceforge.io/crc-catalogue/all.htm):
check_string_matches_canonical_iso_hdlc_value
CRC-32/ISO-HDLC of the standard "123456789" check string is
0xCBF43926. This is THE canonical vector for the algorithm.
empty_payload_yields_zero_crc
init=0xFFFFFFFF, xorout=0xFFFFFFFF → empty payload CRC is 0.
single_zero_byte_has_a_specific_value
CRC-32/ISO-HDLC of [0x00] is 0xD202EF8D — well-known constant.
flipping_a_single_payload_byte_changes_the_crc
Sensitivity property: any one-bit flip MUST change the CRC.
Catches a stuck CRC implementation.
iso_hdlc_distinguishes_from_castagnoli_for_same_input
CRC-32C/Castagnoli of "123456789" is 0xE3069283.
Our value MUST differ. Documents the failure mode for a future
reviewer who fires the test.
known_short_inputs_have_documented_crcs
Three additional vectors: "a", "abc", "hello world".
Each pins a specific 32-bit value against the active polynomial.
crc_is_deterministic_across_repeated_calls
Sanity for pure-function correctness.
These tests are no_std-compatible so they run in BOTH feature configs.
The no_default count therefore jumps from 80 to 87.
ADR-124 status (iter step 0 sibling check):
- docs/adr/ADR-124-rvagent-mcp-ruvector-npm-integration.md unchanged
at 431 lines. SENSE-BRIDGE scope remains orthogonal.
ACs progressed:
- ADR-119 §2.4 "CRC-32/ISO-HDLC" contract — the test surface now
catches any future PR that swaps the polynomial. crc 4.x ships
CRC_32_ISO_HDLC alongside half a dozen other CRC-32 variants;
a typo in src/frame.rs::CRC32_ALG could otherwise silently flip
the wire-format contract.
Test config:
- cargo test --no-default-features → 87 passed (80 + 7 no_std-compat)
- cargo test → 262 passed (255 + 7)
Out of scope (next iter target):
- PR-readiness pivot: CHANGELOG, witness bundle, AC closeout table.
External-resource-gated work (KIT BFId, Pi5/Nexmon) still skipped.
Co-Authored-By: claude-flow <ruv@ruv.net>
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