Portable engineering policies for coding agents — git, testing, logging, and language conventions written once and referenced everywhere
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Cursor rule Claude CodeCursor
Use when two or more agent sessions may work on the same repository concurrently — covers the per-feature lock-file protocol, stale-lock detection, worktree isolation rules, and what to do when a feature is already locked.
Cursor rule Cursor needs its repo
Use when writing tests for critical business logic, auditing test suite quality beyond line coverage, or interpreting surviving mutants — covers mutation operators, mutation score thresholds, and tooling (mutmut, Stryker, gremlins) for Python, TypeScript/JS, and Go.
Cursor rule Cursor
Use when diagnosing slow code, high memory usage, or CPU spikes — language-agnostic profiling workflow: form a hypothesis, identify the hot path, benchmark before and after, and interpret profiler output. Includes Python (cProfile, py-spy), Go (pprof), and Node.js (--inspect, clinic.js) tooling.
Cursor rule Cursor
Use when starting a complex multi-step task, a research project, or any task requiring more than 5 tool calls — creates and maintains taskplan.md, findings.md, and progress.md to preserve state across context resets.
Cursor rule Cursor
Use when asked to port, migrate, or add equivalent agent instructions, skills, or custom sub-agents for a different coding tool than the one already configured — e.g. "add Cursor support from our CLAUDE.md", "we're switching from Cursor to Codex, port our rules", "make this work for Copilot too", "port our review…
Cursor rule Cursor
Use on the first run in a project, or when asked to set the harness up, tailor it to this repository, or work out which conventions apply here — inventories what the project already does, interviews the owner about the decisions only they can make, and applies a confirmed plan without overwriting existing setup.
Cursor rule Cursor
Use when writing or reviewing Python code — naming conventions, type hints, common pitfalls (mutable defaults, bare except, is-vs-==), and testing structure.
Cursor rule Cursor
Use when writing, reviewing, or optimizing React or Next.js code — component architecture, hooks rules, server vs. client components, data fetching patterns, bundle size, and accessibility in React.
Cursor rule Cursor
Use before restructuring code — covers behavior-preservation contracts, characterization tests, incremental reversible steps, and protected public contracts. Ensure refactoring remains a code change, not a feature change.
Cursor rule Cursor
Use before implementing a significant feature or change when requirements are ambiguous, underspecified, or likely to have multiple reasonable interpretations, or when a requirement arrives pre-formed as an issue, audit finding, or review comment whose claim needs checking — covers verifying the premise before acting…
Cursor rule Cursor
Use when reviewing code for security vulnerabilities, performing a security audit, or checking for OWASP Top 10 issues — covers injection flaws, broken access control, cryptographic failures, secrets exposure, dependency vulnerabilities, and language-specific pitfalls for Python, TypeScript/JavaScript, and Go.
Cursor rule Cursor
Use when designing classes or APIs to evaluate SOLID compliance — SRP, OCP, LSP, ISP, DIP. Covers what each principle means, how to diagnose violations by symptom, and how to refactor.
Cursor rule Cursor
Use when writing tests, deciding on test coverage, choosing between unit/integration/E2E tests, applying TDD, or reviewing test quality — covers rigor tiers, the Red-Green-Refactor cycle, coverage requirements, and Playwright for UI testing.
Cursor rule Cursor
Use when writing, reviewing, or refactoring TypeScript or JavaScript code — naming conventions, type annotations, private fields, null vs. undefined, async/await pitfalls, and module structure.
At most 3 mods per repository are shown here, and a mod shipped inside a plugin is left to that plugin's page — the rest are on their repository pages: