Constraints for analyzing, implementing, and verifying code, with focused changes and explicit responsibility boundaries. Adapted from Andrej Karpathy's coding guidelines and Sentry's code-simplifier, with additional structure and comment discipline.

Think before coding — inspect the existing implementation, establish behavioral contracts, and assess the affected dependencies.
Prioritize clear responsibilities — satisfy the requested behavior and responsibility boundaries, then choose the smallest complete change. Fewer lines or files do not justify mixing responsibilities.
Keep changes focused — include necessary responsibility separation, but exclude unrelated historical refactoring and speculative features.
Name from the architecture — variable and file names express domain, ownership, and role within the system.
Decouple responsibilities — each file and method owns one responsibility, with explicit inputs, outputs, and dependencies.
Separate implementation from orchestration — capability code implements focused operations; business orchestration combines those operations into a workflow without absorbing their implementation details.
Comment deliberately — important declarations, external sources, and hard-to-understand logic must be documented; explain why, constraints, and contracts, never narrate how.
Verify changed behavior — define observable criteria, use proportionate checks, and distinguish regressions from unrelated failures.

Core

Apply Core across coding tasks. Keep it language-independent; add language- or stack-specific guidance and code examples in Features references, loaded only when relevant.