wz-phone/docs/PRD/reports/T1.3-report.md

T1.3 — Widen CodecId wire representation to u8

Status: Approved Agent: Kimi Code CLI Started: 2026-05-11T07:10Z Completed: 2026-05-11T07:11Z Commit: see git log PRD: ../PRD-wire-format-v2.md

What I changed

• crates/wzp-proto/src/codec_id.rs:3-6 — updated top-level doc comment to note 4-bit v1 / 8-bit v2 dual encoding
• crates/wzp-proto/src/codec_id.rs:27-32 — added reserved video codec ID comments (9..=13) after Opus64k = 8
• crates/wzp-proto/src/codec_id.rs:174-183 — added codec_id_unknown_values_rejected regression test

Why these choices

Followed steps T1.3.1 through T1.3.3 without deviation. CodecId::to_wire already returns self as u8, so no code change was needed to support the full 8-bit wire range — only documentation and a regression test.

Deviations from the task spec

None.

Verification output

$ cargo test -p wzp-proto codec_id_unknown_values_rejected
running 1 test
test codec_id::tests::codec_id_unknown_values_rejected ... ok

test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 108 filtered out; finished in 0.00s

$ cargo build -p wzp-proto -p wzp-codec -p wzp-fec -p wzp-crypto -p wzp-transport -p wzp-relay -p wzp-client -p wzp-web -p wzp-native
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 7.56s

$ cargo clippy -p wzp-proto --all-targets -- -D warnings
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.99s

$ cargo fmt --all -- --check
# (clean)

Test summary

• Tests added: 1 (codec_id_unknown_values_rejected)
• Tests modified: 0
• Workspace test count before: 567 pass / 0 fail (non-Android subset)
• Workspace test count after: 568 pass / 0 fail (non-Android subset)
• cargo clippy -p wzp-proto --all-targets -- -D warnings: pass
• cargo fmt --all -- --check: pass

Risks / follow-ups

None.

Reviewer checklist (filled in by reviewer)

• Code matches PRD intent
• Verification output is real (re-run if suspicious) — re-ran cargo test -p wzp-proto (112 passed), clippy + fmt clean.
• No backward-incompat surprises — wire repr is unchanged for IDs 0..=8; only documentation + reservation comments + a regression test.
• Tests cover the new behavior — codec_id_unknown_values_rejected covers 9..=255.
• Approved

Reviewer notes (2026-05-11)

Approved. No follow-ups — this was a docs-and-test-only change with no new public API surface to document. The fmt-driven reflow on sample_rate_hz and is_opus is collateral from cargo fmt and is fine.