CLAUDE.md

Behavioral guidelines to reduce common LLM coding mistakes. Merge with project-specific instructions as needed.

Tradeoff: These guidelines bias toward caution over speed. For trivial tasks, use judgment.

Shared Rules

Shared repository rules live here:

• ./.shared-agents/common/linting.md

Validation

Before finishing any code task, follow:

• ./.shared-agents/common/linting.md

Do not finish with known safe-to-fix issues in the changed scope.

Model Selection

For cost efficiency without quality loss, use the opusplan alias (/model opusplan): Opus plans and reviews, then auto-switches to Sonnet for execution within the same session. Keep planning and final review on the top model and let Sonnet handle mechanical execution. Do not downgrade further (e.g. Haiku) for non-trivial work — failed loops cost more than they save.

Route subagents by difficulty — each agent's own model sets its cost, whatever model the main session runs:

• research and hard analysis → researcher (Opus)
• implementing an already-decided plan → executor (Sonnet)
• codebase search → Explore (Haiku), rather than reading widely inline, so the orchestrator's context stays clean

Keep planning and review on the main thread.

Keystone

Invoke the keystone skill before implementing non-trivial logic, structuring a module, or judging whether existing code reads well — it carries the reading standard all code is written to. React components, pages, and features take keystone-react on top of it.

1. Think Before Coding

Don't assume. Don't hide confusion. Surface tradeoffs.

Before implementing:

• State your assumptions explicitly. If uncertain, ask.
• If multiple interpretations exist, present them - don't pick silently.
• If a simpler approach exists, say so. Push back when warranted.
• If something is unclear, stop. Name what's confusing. Ask.

2. Simplicity First

Minimum code that solves the problem. Nothing speculative.

• No features beyond what was asked.
• No abstractions for single-use code.
• No "flexibility" or "configurability" that wasn't requested.
• No error handling for impossible scenarios.
• If you write 200 lines and it could be 50, rewrite it.

Ask yourself: "Would a senior engineer say this is overcomplicated?" If yes, simplify.

3. Surgical Changes

Touch only what you must. Clean up only your own mess.

When editing existing code:

• Don't "improve" adjacent code, comments, or formatting.
• Don't refactor things that aren't broken.
• Match existing style, even if you'd do it differently.
• If you notice unrelated dead code, mention it - don't delete it.

When your changes create orphans:

• Remove imports/variables/functions that YOUR changes made unused.
• Don't remove pre-existing dead code unless asked.

The test: Every changed line should trace directly to the user's request.

4. Goal-Driven Execution

Define success criteria. Loop until verified.

Transform tasks into verifiable goals:

• "Add validation" → "Write tests for invalid inputs, then make them pass"
• "Fix the bug" → "Write a test that reproduces it, then make it pass"
• "Refactor X" → "Ensure tests pass before and after"

For multi-step tasks, state a brief plan:

1. [Step] → verify: [check]
2. [Step] → verify: [check]
3. [Step] → verify: [check]

Strong success criteria let you loop independently. Weak criteria ("make it work") require constant clarification.

5. Design Patterns

Reach for an established pattern before inventing structure.

When a problem maps cleanly to a known pattern, use it — don't build a bespoke solution that a reviewer will have to reverse-engineer.

Context7

Context7 is the default source for library and framework documentation.

• Use the context7 tool when you need library or API documentation.
• Use the context7 tool when you need code generation, setup instructions, or configuration steps.
• Do not rely on memory for library versions or APIs when verification is needed.

Shell Tool Preferences

Prefer modern CLI search tools for efficiency:

• Use fd instead of find.
• Use rg instead of grep.

If either tool is missing, inform the user and ask before running an install command.

These guidelines are working if: fewer unnecessary changes in diffs, fewer rewrites due to overcomplication, and clarifying questions come before implementation rather than after mistakes.