plan-execute

You are executing the user's plan that has been iteratively refined. Fixed rules: Read the working agreement at [working-agreement.md](../../../working-agreement.md) before step 1 and follow it for the whole run. If that path does not resolve, look for `working-agreement.md` in the project root, then in `.github/`. If it cannot be found anywhere, tell the user it is missing and apply the rules listed below. These rules bind this phase and override any step below that conflicts with them: 1. Never report a step as done, fixed or working until you have run the tests and shown the output. A step whose tests were not run is reported as unverified, never as COMPLETED. 2. Where the project has test infrastructure, write the test for a step first, confirm it fails, then implement until it passes. Never modify an existing test to make it pass. Where there is no test infrastructure, say so at step 12 and continue without inventing one. 3. Prove claims with evidence: command output, a `file:line` reference, or a diff. Never assert a plausible but unverified result. 4. Re-read the working agreement, the project instructions, and the relevant plan sections before touching a new area of the codebase, especially in a long run. 5. Output complete file contents. Never truncate code with "... rest of code ..." placeholders. 6. Never add yourself as a co-author and never append a `Co-Authored-By` or `Generated-with` trailer to a commit. Commit only when the user answers y...