check-dependency-capabilities

name	check-dependency-capabilities
description	Use before writing any non-trivial utility, helper, algorithm, data transformation, or wrapper that an installed dependency might already provide. Symptoms — about to hand-roll debounce/merge/groupBy/retry, a stream operator, a validator, or a wrapper around a first-party host/SDK package whose API you don't have in context.

Check Dependency Capabilities

Before hand-writing a utility/helper/wrapper, check whether an installed package already exports it. The index under index/ is generated from every dependency's .d.ts (the authoritative, version-matched API surface).

Steps

0. Ensure the index exists and is fresh. The index is gitignored, so on a fresh clone it won't exist yet. Run the generator if index/symbols.tsv is missing, if index/.manifest.json doesn't match current dependency versions, or if package.json/package-lock.json changed since the manifest:

   node .claude/skills/check-dependency-capabilities/generate.mjs
   

   It regenerates only changed packages (near-instant when nothing changed; full build only on first run).

1. Grep the symbol table for the capability — try the concept and likely names:

   grep -iP '\t(function|const|type|class)\t' .claude/skills/check-dependency-capabilities/index/symbols.tsv | grep -i 'debounce'
   

   Columns are symbol⇥kind⇥package⇥jsdoc-first-line. A hit means a package already provides it.

2. Read the matched package's signatures for exact usage (one scoped file, e.g.):

   cat .claude/skills/check-dependency-capabilities/index/lodash-es.md
   

   (Slug rule: drop a leading @, replace / with __ — @novasamatech/host-api → novasamatech__host-api.md.)

3. Decide. Use the existing export if it fits. Only if nothing matches, write new code — and say in one line what you searched and why nothing fit.

Maintenance

The index is gitignored (project-specific derived data) and regenerated incrementally by generate.mjs (driven by index/.manifest.json). Config (scope, dev deps) lives at the top of generate.mjs. The generator and its node:test suites are self-contained in this folder — no project wiring.