Knowledge indexing for Obsidian vaults — explore your notes by concept, not keyword. Enzyme reads the tags, links, and folders you already use, builds semantic clusters, and generates catalysts: thematic questions that surface content keyword search won't find. Ships as a small CLI binary bundled in the plugin. The `/enzyme` skill lets Claude Code see what's trending in your vault with `petri`, search by theme with `catalyze`, and create notes that inherit tags from retrieved content. Requires a BYOK OpenAI or OpenRouter API key for catalyst generation.