AGENTS.md

AGENTS.md holds the cross-tool project rules — the conventions any coding agent must follow in this repo. Two modes, detected by whether one already exists at the target: Create (none exists) infers rules from evidence; Update (one exists) merges a new rule into the right section and trims what it duplicates. Updating is the harder half: never blind-append.

Not the same as adjacent artifacts — keep them distinct:

• CLAUDE.md and /init are Claude Code's own memory, not the cross-tool rulebook. A tool that reads its own memory file instead of AGENTS.md gets a one-line import pointing at it (plus any tool-only overrides), never a second copy of the rules.
• settings.json is harness config (the update-config skill), not project conventions.

When a rule belongs in AGENTS.md, put it there — don't scatter the same rule across these files.

Conventions this file must follow (and enforce)