every.channel/evolution/proposals/ECP-0047-coverage-reporting.md

ECP-0047: Coverage Reporting (cargo-llvm-cov)

Why

We want high confidence in stream processing, transport, and cryptographic verification code. That requires:

• repeatable coverage measurement, and
• a visible baseline so we can drive coverage up without guessing.

Proposal

Adopt cargo llvm-cov as the canonical Rust coverage tool in this repo (already provided by flake.nix).

Add:

• scripts/coverage.sh to generate an HTML report and write a summary table to tmp/coverage/summary.txt.

Notes:

• #[ignore] E2E tests are excluded by default and do not contribute to coverage.
• We will expand unit and non-ignored integration tests in the crates that matter most for correctness (chunk framing, manifest validation, encryption, ingest adapters).

Reversibility

High. This adds a script and a convention; it does not change runtime behavior.