catalyst-functions

How It Works

Intent check — do this first:

• If the user is asking a how-to or conceptual question ("how do I write a function", "show me a Basic I/O handler", "how does Security Rules work"), answer directly with the correct code or explanation. Do NOT inspect the working directory, do NOT generate a CLAUDE.md, do NOT switch into codebase-analysis mode. Empty directory = fine for how-to questions.
• Only inspect the filesystem when the user explicitly asks to scaffold, add, or deploy something in their project.

1. Verify local scaffold (only when scaffolding, not for how-to questions) — both catalyst init and functions:add support non-interactive mode (CLI v1.27.0+). Check whether .catalystrc exists. If missing, use MCP tools to get the org ID and project ID, then run:

   catalyst init --org <orgId> -p <projectId> -ni
   

   Never ask the user to run catalyst init interactively. NI mode can only link an existing project — if none exists, tell the user to create one in the console first. catalyst.json does not exist yet after init -ni — that is expected. Add functions next (this creates catalyst.json):

   catalyst functions:add --name <name> --type <type> --stack <stack> -ni
   # e.g. catalyst functions:add --name api --type aio --stack node20 -ni
   

2. Identify the function type — Basic I/O for simple request/response, Advanced I/O for raw HTTP control, Event for trigger-based, Cron/Job for scheduled, Integration for Zoho service events, Browser Logic for Puppeteer.

3. Load references/functions-basics.md — for the matching handler signature, catalyst-config.json keys, SDK init pattern, and CORS setup.

4. Load references/functions-advanced.md — for file uploads (busboy), streaming responses, error handling, or chaining functions.

5. Load references/api-gateway.md — for routing rules, rate limiting, or gateway-level CORS.

6. Validate config — Confirm catalyst-config.json uses deployment + execution keys only. Never use function or entry_point.