tests/overhead_invariants.rs has never run in CI — INV-2/INV-3 are decorative, and #263's INV-4/INV-4b would land unfailable

[fcostaoliveira]

Found while reviewing PR #263.

tests/overhead_invariants.rs has never been executed by CI. Every cargo test invocation in .github/workflows/ci.yml is one of:

• cargo test --lib --bins --release (line 65) — --lib --bins excludes every tests/*.rs integration target
• cargo test --test integration_cli --release (line 70)
• 13 × cargo test --test integration_<engine> --release

overhead_invariants is never named, and there is no bare cargo test, no --tests, and no --all-targets test run. Makefile: test is cargo test --lib --release. cargo clippy --all-targets compiles the file but never runs it.

So INV-2 and INV-3 — the client-overhead invariants — have been decorative since they were added. They can only fail if someone types a bare cargo test locally.

This is not hypothetical for new work either: PR #263 adds INV-4 and INV-4b to the same file, and they would land unfailable.

Fix: add cargo test --test overhead_invariants --release to the test job, or change line 65 to cargo test --release so all targets run.

Worth checking at the same time: tests/integration_vertex.rs also has no CI job. That one is probably intentional (Vertex AI is cloud-only and needs GCP credentials), but it should be an explicit, documented exclusion rather than an accident of the same omission.

Second-order: once the file actually runs, expect the existing invariants to need attention — they have never been enforced, so nothing guarantees they currently pass in a clean CI environment. A reviewer ran them locally at 5/5 on a PR branch, but that is one machine, not the CI image.