Establish which checks still catch real regressions and which costs can be removed without losing that protection. The outcome may be a verified fix, an evidence-backed recommendation, or an explicit decision to stop.

Follow the checkout's , testing guide, and contribution rules. Use their current commands and pinned toolchain, rather than commands remembered from an earlier audit. Preserve the requested scope: investigation alone does not authorize edits; this skill does not grant permission to publish issues, push, or merge. Existing user authorization still applies. Keep audit notes and raw results outside the tracked tree, normally in a task-specific directory.

Fetch when the user asks for latest main. Pin the baseline SHA and inspected workflow revision; use an isolated worktree when changing or comparing code. Do not modify another task's checkout. Record dirty changes and the exact command, toolchain, host, selected tests, instrumentation, and prerequisites. An old run is evidence for its executed revision, even if main advances.

Trace workflow triggers, changed-path selection, job dependencies, reusable actions, package scripts, test discovery, artifact producers, and report gates through to the commands that actually execute. Include scripts, generated data, runtime registration, and subprocess boundaries missing from import graphs. Check positive and negative selection paths: required files must be discovered once per intended test configuration; deliberate platform/configuration repeats are separate coverage. A missing explicit test or missing required report must not turn green. Optional lanes may skip; preserve their stated prerequisites.

Use existing timing and failure artifacts to select suspicious families. Run relevant checks to establish a baseline; reserve a full local suite for broad CI diagnosis or uncertainty that focused checks cannot resolve. Do not rebuild or rerun an unchanged complete suite after every documentation edit.

For each candidate, state the expected observable behavior and its owner, then construct the smallest reproduction against production behavior. Follow the producer and affected consumers before deciding where to fix it.

Classify findings as reproduced defects, supported costs, hypotheses, or unavailable evidence. Record the baseline command, observed output/exit status, expected result, affected scope, and competing explanation. A failure on main may be pre-existing; that does not by itself make it irrelevant to a CI audit. Attribute PR failures using the executed revision and a clean baseline, not just their resemblance to a previous failure. Retry only to test a specific transient explanation; retain the original failure and stop when repetition adds no evidence. A passing retry does not establish a root cause or a fix.

Read measurement and CI checks when investigating slowness, caching, runner waits, shared artifacts, or log noise. Compare equivalent completed work before claiming a speedup. Distinguish setup/build time, test execution, coverage instrumentation, dependency waits, and runner scheduling; state which costs remain unmeasured.

Prefer removing proven duplicate preparation, reusing immutable setup, and reducing repeated subprocess work before shrinking correctness coverage. Preserve independent sessions where lifecycle or concurrency is the oracle. Keep live tests fresh; a cached previous pass cannot validate current host, installed provider contents, permissions, or external state.

If implementation is authorized, make the smallest structural change at the owning boundary and add a regression that fails on the baseline for the right reason. Retest affected consumers and meaningful negative paths; verify cache invalidation or discovery when those mechanisms change. Read the installed Turbo documentation before changing its configuration or commands.

Run the repository's applicable checks and inspect complete current-head CI results before an authorized merge. Preserve required coverage and discovery gates. Do not suppress a failure, add blanket retries, raise timeouts, or delete distinct assertions solely to make CI green. Changes to these controls need their own demonstrated reason and retained failure detection.

Report each confirmed issue with exact revision, reproduction, consequence, proposed correction, and validation limits. Report performance with workload and measurements, not just a percentage. Use English issue/PR records when requested; follow the user's assignment, commit identity, review, and merge preferences without assuming them for other users. Open ready-for-review PRs only when that lifecycle is authorized. Resolve necessary review findings and check final main against the tested tree after merging.

Stop when the authorized work is verified, remaining benefits are unproven, or further changes would trade correctness for speculative speed. List genuine uncertainties without turning them into additional optimization rounds.