Use cases

A team cutting CI time

Add the three actions to your workflow: your test step runs the selected command, or your normal suite when select says full. Savings depend on structure. In the Cirq monorepo, PRs touching only cirq-google skipped 79.8% of test time; PRs in cirq-core, which every other package imports, skipped 20.2%.

A coding agent running only the relevant tests

siftwise mcp gives an agent three tools: select_tests before it runs tests, triage_failure when tests fail and before it tries to fix them, and explain when a selection or verdict surprises it. Uncommitted work counts, untracked files included. Results stay under 8,000 characters and never contain the API token.

Triaging failures: regression, flaky or pre-existing

The sticky PR comment gets a Failures table (test, verdict, confidence, one reason), new regressions first, never with raw failure messages. To gate on it, set fail-on: new_regression,unknown. Known flakes go in known_flaky; for a PR the base commit's list applies, so a PR can't excuse its own failures. rerun-unknown re-runs unknown pytest failures; one that passes is flaky.

Measuring recall before you rely on it

Set shadow: 10% on the select step. A sampled run still runs the full suite while siftwise stores what it would have selected, then checks every failure against it. Each miss gets a cause: new_test, flaky_history, config_gap (with a suggested [[depends]] rule to review), no_link or unknown. siftwise report shows recall over time, the selective-only figure always next to the overall one.