search-before-buildinglisted

# Search Before Building Before implementing new functionality, verify it does not already exist and that the best option has been considered. ## When to Use - About to add a new helper, utility, or abstraction - Task says "add X" and X sounds like a solved problem - Considering a new external dependency - Agent proposes writing something from scratch without checking first ## Four-Step Check Run in order. Stop when you find a satisfactory answer. ### Step 1 — Repo-first Search the current codebase before anything else: ```bash rg "<keyword>" src/ lib/ --type ts --type js -l rg "<keyword>" --glob "*.py" -l ``` Check: Does equivalent logic already exist? Is it importable as-is, or would it need wrapper work? ### Step 2 — Package registry Search the relevant registry for the project language: | Language | Registry | Search method | |----------|----------|---------------| | TypeScript/JS | npm | `npm search <keyword>` or npmjs.com | | Python | PyPI | `pip index search <keyword>` or pypi.org | | Go | pkg.go.dev | web search `site:pkg.go.dev <keyword>` | | Rust | crates.io | `cargo search <keyword>` | Score each candidate: - Maintenance: last commit < 1 year, open issues ratio - Popularity: weekly downloads or GitHub stars - License: MIT / Apache-2.0 / BSD preferred; check for GPL/commercial constraints - Size: avoid heavy packages for a single feature ### Step 3 — MCP / tool servers Check whether an MCP server already provides this capability: ```bash # List curre