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# Periscope Cursor Engineering Rules

Mandatory for every Cursor agent working on Periscope. This section is copied from `docs/development/CODING_CONSTITUTION.md` and must not contradict that master.

## 4. Testing

- Write tests before considering a slice done. Prefer tests that lock behavior (graph topology, finding codes, via≠pad, review isolation) over tests that assert overlay stamps or file provenance comments.
- `pytest` from the worktree with the project venv. Do not claim green from a system Python missing deps.
- One malformed IC must not kill the whole review; keep per-IC isolation tests.
- Do not add tests whose only job is to require `Native Periscope overlay` in a copied file.
- UI changes: exercise the flow (not a single screenshot). If no browser tools, say what was not verified.
- Installing docs/rules is a docs phase: existence and internal consistency of the seven `.mdc` files plus this master is the check. There is no product pytest gate for markdown-only.