BUILD OS · REUSABLE RULE
Verify the current behavior before asking an agent to refactor it
Rule
Capture the existing behavior and the regression check before broadening a code change.
Why it matters
An agent can satisfy a local request while changing an adjacent behavior that was never named in the prompt.
Failure mode
A change appears correct by inspection, then breaks an unrelated route or user flow.
Implementation
- Inspect the current route and its callers.
- Name invariants and edge cases.
- Choose a focused test or reproducible manual check.
- Review the diff and run the check after the change.
Verification
- The check fails when the original defect is reintroduced.
- Existing nearby flows still pass.
- The final report names files changed and checks actually run.
Evidence and provenance
DocumentéThe published agent workflow note documents the Inspect → Report → Plan → Modify → Verify sequence; no comparative benchmark is implied.
Source updated 2026-09-26: published field note.