This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

A Val Town script that automatically cross-posts Farcaster casts to Twitter/X using Neynar webhooks. It runs as a serverless HTTP endpoint on Val Town's Deno-based platform.

# Type check
deno check index.ts

# Run locally (for testing)
deno run --allow-net --allow-env index.ts

Single-file HTTP handler (index.ts):

• Receives cast.created webhooks from Neynar
• Filters out replies (only cross-posts original casts)
• Downloads images from imagedelivery.net and uploads natively to Twitter
• Appends video/other URLs to tweet text (relies on Twitter unfurling)
• Posts to Twitter using twitter-api-v2 npm package

Key flow:

1. Webhook POST → parse CastCreatedWebhook payload
2. Skip if reply (parent_hash !== null)
3. Separate embeds: images → upload to Twitter; videos/URLs → append to text
4. Validate 280 char limit
5. Tweet via Twitter API v2

• Uses Deno.env.get() for environment variables
• Imports npm packages via npm: prefix (e.g., npm:twitter-api-v2)
• HTTP trigger pattern: export default async function(req: Request): Promise<Response>
• TypeScript with strict mode enabled

• TWITTER_API_KEY
• TWITTER_API_SECRET
• TWITTER_ACCESS_TOKEN
• TWITTER_ACCESS_TOKEN_SECRET

Twitter API keys must have OAuth 1.0a with Read/Write permissions configured.