function-dev

# Serverless Function Development on Butterbase Guide for developing and deploying serverless functions on Butterbase's Deno runtime. Covers handler signatures, trigger types, database access, environment variables, and testing. --- ## 1. Handler Signature Every function exports a single `handler` function with this signature: ```typescript export async function handler( request: Request, context: { db: PostgresClient, // RLS-aware DB client env: Record<string, string>, // env vars set on the function user: { id: string } | null, // present for HTTP+auth:required; null for cron waitUntil: (p: Promise<unknown>) => void, // background work after Response (≤30s) idempotency: { claim: (key: string, opts?: { scope?: string; ttlSeconds?: number }) => Promise<boolean> } // atomic dedup for webhook retries } ): Promise<Response> ``` **CRITICAL**: The handler MUST return `new Response()` (Web API standard). Do NOT return plain objects. **Correct:** ```typescript return new Response(JSON.stringify({ message: "ok" }), { status: 200, headers: { "Content-Type": "application/json" } }); ``` **Wrong (will fail):** ```typescript return { status: 200, body: "ok" }; // NOT a Response object! ``` --- ## 2. Trigger Types ### HTTP Trigger Invoke the function via an HTTP request. ```json { "trigger": {...