You are helping me build the following AI agent workflow.

## Goal
WhatsApp Personal AI Assistant: Send voice, images, or PDFs via WhatsApp to get AI-powered scheduling, email management, web searches, and audio responses.

## Specification
- What it does: Send voice messages, images, or PDFs via WhatsApp to instantly get help with scheduling, email management, web searches, and receive audio responses. The system transcribes your inputs and uses Gmail and Google Calendar to execute these tasks directly within the chat.
- Trigger: Triggered by an event (Event · on WhatsApp message)
- Autonomy: Fully hands-off
- Expected setup effort: a few focused days
- Tools/services involved:
  - WhatsApp Business Cloud: Receive and send messages
  - OpenAI: Transcription, image analysis, TTS
  - Anthropic Chat Model: Agent reasoning and tool use
  - Gmail: Send and search emails
  - Google Calendar: Create and read events

## Known pitfalls, handle each one explicitly in your implementation
1. WhatsApp has strict template message rules for initiating conversations so you must use pre-approved templates for outbound messages to avoid bans.
2. Audio transcription latency can frustrate users so implement asynchronous processing with a status update mechanism rather than blocking the webhook.
3. Tool execution failures like Gmail auth errors will crash the flow so add robust error handling that returns a polite failure message instead of crashing.
4. Token limits in Anthropic may truncate long context from PDFs so implement chunking strategies for document extraction to stay within safe bounds.

## Reference implementation
https://n8n.io/workflows/8920 (workflow template)
Fetch and inspect this before building. If it matches my stack, adapt it;
if not, rebuild the pattern with my tools.

## Process requirements
1. Before building: ask me which of the listed tools I actually use and
   what my platform is (n8n / Make / code / other). Do not assume.
2. Adapt the pattern to my answers; do not force the reference stack.
3. Address every pitfall above; tell me how you handled each.
4. Provide a test plan I can run before letting this touch real data.
5. Ask before any step that sends messages, modifies data, or spends money.

Source: https://usecasesforagents.com/use-case/whatsapp-personal-ai-assistant/ via usecasesforagents.com