fix(test): a partial test run says what it did not cover

[TinDang97]

A partial test run says what it did not cover

Across a full session I reported "suite green" from pytest add-method/tests/ while add-method/tooling/ — 8 checks including the ENGINE_MD5 pins CI also runs — was red. Every green was true of the suite I ran and silent about the one I didn't, and a red branch reached the point of merge on the strength of it.

The repo was not at fault. pytest.ini already made a bare pytest from add-method/ collect everything, and its comment already explained why tooling/ had to stay collectable. Nothing here stops a narrow run, and nothing should — running one directory while iterating is usually the right thing to do. What's fixed is the ambiguity:

================================= PARTIAL RUN ==================================
not collected: tooling — this run says nothing about it.
full suite:    python3 -m pytest -q      (from add-method/, what CI runs)

Design

• Roots are discovered, never listed. A hand-maintained list would have omitted tooling/ for the same reason a person does: it doesn't look like a test directory, it looks like the engine's home.
• No off switch. The one thing this must survive is somebody finding it inconvenient.
• Never fails the run. An error would only teach people to silence it. It informs; it does not gate.
• Silent on a complete run. A notice that appears every time is one nobody reads.

Three real defects, each caught by the new checks rather than by reading

1. tests/eval had never run — not in a bare run, not in CI. norecursedirs matches a basename, so the entry meant for the top-level eval/ fixture project also swallowed the eval driver that pytest.ini's own comment names. Two tests, absent from every count this repo has ever reported.
2. The first fix broke position-independence. --ignore=eval resolves against rootdir, so it stopped applying the moment pytest ran from the repo root — caught by this task's own receipt run. Now collect_ignore anchored to the conftest's directory, which holds from either invocation point.
3. import conftest silently resolved to tests/engine/conftest.py on a full run. It passed in isolation and failed 700 tests in — the same class of mistake this task exists to fix: a narrow run agreeing with you and a full run not.

Verification

• Collection 715 → 721
• 714 passed, 7 skipped, verified from both add-method/ and the repo root
• partial-run-visible gate PASS @ plan, receipt runs/2.md, freshness: fresh
• Re-frozen once to widen scope to pytest.ini, after the reachability check found the uncollected suite on its first execution