The coverage review found `InvalidLength {declared, have}` is a
zombie: `DatagramReader::feed` never returns `Err` — it buffers
partial frames indefinitely, and the truncated-stream contract is
carried by `is_mid_datagram` (the codec diagnostic) plus
`TunnelIoError::TruncatedDatagram` (the session surface). The
variant's doc claimed it was the truncated-stream error; no spec
(ADR-003, wire.md, bast.md) names it, and no external consumer
exists (verified 2026-09-08 per ADR-005's N-3 amendment), so the
API window is open — removed before the first consumer pins it.
Also removes the `unreachable!` arm its removal strands in the
`local` adapter's recv mapping (a no-panic path; single-variant
destructure now), and records the planned-shape correction in the
completed wire-codec task doc.
Verified: cargo test (--all-features and default), clippy
--all-targets -D warnings, fmt --check, wasm32 check + clippy — all
clean.
glm-5.3-flash
4014ba66a9