Add CLAUDE.md with project-specific rules (test structure, naming conventions, MCP tools reference). Add .mcp.json for rust-mcp and crates-io MCP servers. Add rust-toolchain.toml pinning stable with rustfmt and clippy. Add .claude/settings.json with PostToolUse hook that runs cargo test automatically after every file edit. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>