Ethan has 700+ custom tools but no reverse map from a *problem phrase* to the tool that already solves it, so new sessions keep rebuilding near-duplicates (tool-recall, tool-rediscovery-card, tool-half-life all attack this after the fact). This builds a one-shot semantic index of every tool's purpose line and injects a 'you already built this' warning into any session where Ethan states an intent that matches an existing tool above threshold.
Create ~/bin/tool-prior-art: (1) build step walks ~/bin/* and ~/.claude/skills/*, extracts the first comment block / --help line of each as a purpose string, writes ~/.cache/tool-prior-art/index.jsonl; (2) embed each purpose via the existing embed-batch-submit tool, cache vectors keyed by file mtime so rebuilds are incremental. Then add a UserPromptSubmit hook in ~/.claude/settings.json that pipes the prompt to `tool-prior-art match --top 3 --min-score 0.72`; on a hit it emits additionalContext: 'Prior art: ~/bin/