* chore(blocking-io): fail-loud repo-root resolution and shared detector CLI shim
The three detectors resolved REPO_ROOT with depth-indexed
Path(__file__).resolve().parents[4]. If a detector file ever moves to a
different directory depth, scan roots resolve under the wrong directory
and the detector reports zero findings with no error — a silent-zero
failure shape for a detection tool.
- Add support/detectors/repo_root.py: resolve the repo root by walking
upward to the .git marker (checked with exists() so git worktrees,
where .git is a file, also resolve), raising RuntimeError when no
marker is found. All three detectors use it at import time, so a
relocated detector fails loudly instead of scanning an empty tree.
- Extract scripts/_detector_cli.py from the three character-identical
CLI shims; the sys.path computation lives in one place and raises
when backend/tests cannot be found.
- tests/test_detector_repo_root.py pins: resolution from an unmarked
location raises instead of returning an empty scan; all three
detectors share the resolved root; each CLI shim delegates to its
detector.
Testing: backend `make test` (4278 passed); smoke-ran
`make detect-blocking-io`, `make detect-thread-boundaries`, and
`scripts/scan_changed_blocking_io.py --base upstream/main`.
Closes#3510 (review follow-up to #3503).
* chore(blocking-io): declare detector modules import-only, drop script-mode residue
Adversarial review caught that blocking_io_static.py and
thread_boundaries.py kept shebangs and __main__ blocks but can no longer
run as plain scripts: the new `from support.detectors.repo_root import`
executes before anything puts backend/tests on sys.path, so direct
invocation dies with ModuleNotFoundError before argparse.
Direct execution was never a documented entry point (Makefile targets,
the scripts/ shims, the blocking-io-guard skill, and tests all go
through the support.detectors package), so converge on import-only
instead of re-adding per-module bootstrap: drop the shebangs and the now
unreachable __main__ blocks (plus the `import sys` they kept alive) and
state the supported entry points in each module docstring. The shim
delegation tests in test_detector_repo_root.py pin the supported CLI
paths.
Testing: backend `make test` (4278 passed); `make detect-blocking-io`
and `make detect-thread-boundaries` smoke-ran.
* feat(blocking-io): add changed-lines blocking-IO scanner (L1)
* feat(blocking-io): add scan-changed CLI wrapper
* feat(skill): add blocking-io-guard developer SOP skill
* docs(blocking-io): point contributors at the blocking-io-guard skill
* style(blocking-io): apply ruff format to scanner and tests
* docs(backend): document changed-lines blocking-IO scanner in CLAUDE.md
* feat(skill): add post-fix re-scan check and PR batching policy
* refactor(skill): fix SOP step ordering, align template with repo conventions
- Move re-scan into an explicit 'apply the fix' step (was wedged after
anchor generation while telling you to go back before the anchor)
- Renumber steps 0-6; drop undefined 'L1' jargon
- Mode A: document that the diff is <base>...HEAD (commit first)
- Mode B: prefer make detect-blocking-io + findings JSON file
- anchor template: module-level pytestmark per tests/blocking_io convention
- CLAUDE.md: fix 'git diff --base' phrasing
* fix(skill): catch findings introduced without touching the blocking line
Review follow-up: changed-line intersection alone misses the case where a
new async caller exposes an old sync helper — the static finding sits on
the untouched blocking line, so Mode A returned empty and the SOP stopped
on a false 'no blocking-IO surface'.
Selection is now a union over the changed files:
- findings on added lines of git diff <base>...HEAD (kept: a second
identical symbol in an already-flagged function collides on the stable
key and only this selection sees it);
- findings new versus the merge base, matched by (path, function,
symbol) — never line numbers.
Base sources are materialized via git show <merge-base>:<path>; files
absent at base count every head finding as new. SKILL.md now states the
residual same-file-only blind spot (cross-file async callers) instead of
treating an empty list as proof of zero exposure, and only requires
reading sop-skeleton.md when generalizing to another detector domain.
* docs(skill): examples teach test-writing, the teeth check defines the rule
All examples in the references/template are filesystem-flavored; make
explicit that they are instances, not the SOP's boundary — the same rules
apply to every detector category (FILE_IO, HTTP, SUBPROCESS, SLEEP) and
acceptance is always red/green teeth, never similarity to an example.
Neutralize the template's arrange comment accordingly.
* fix(blocking-io): harden changed-lines scanner per review
- Dedup the union selection by the stable key (path, function, symbol)
instead of dict identity, so a future selector returning copied dicts
cannot silently empty the result.
- parse_changed_lines now handles any unified diff: context lines advance
the new-file counter, \-markers and deletions do not, and the counter
resets at each +++ header. Previously correct only for --unified=0.
- Add blocking_io_static.scan_source (in-memory scan); base-version
comparison no longer round-trips through temp files.
- Empty Mode A report now prints the same-file-only reachability caveat
at the point of use instead of relying on the SOP text alone.
* docs(skill): bound best-effort cleanup when the offload sits in finally
Lesson from the #3505 review: the SOP routinely drives 'offload the
cleanup branch' transformations, and an awaited cleanup in finally can
mask or stall the primary exception. One sentence in Step 2 closes that
gap at the point where the fix is written.
AochenShen99