WhatsApp support bot with Google Drive RAG, GPT-4.1-mini and Cohere reranking

WhatsApp RAG Agent (Text + Voice) with Weekly Google Drive Sync

One-line summary : Answers WhatsApp in under 100 words, understands voice notes, and retrieves trusted answers from your Google Drive docs (RAG) kept fresh weekly.

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What this template does

• Reply to WhatsApp messages in a polite, human tone with ≤100 words.
• Understands text and voice notes: auto-downloads audio and transcribes to text.
• Retrieves answers from your knowledge base (RAG): Google Drive docs → chunk → embed → store in Supabase → rerank with Cohere.
• Keeps short-term memory across the conversation to avoid repetition.
• Weekly doc sync from a selected Google Drive folder so non-technical staff can update content without touching n8n.

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Why it matters

• Zero busywork: Update a Google Doc; the bot learns it on the next sync.
• Trustworthy answers: Responses come from your vetted docs, not random web text.
• Voice-first friendly: Handles the WhatsApp reality of “send a voice note.”
• Safer by design: Guardrails—no pricing unless in KB, no pushy sales, no medical advice.

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Triggers

• WhatsApp Trigger: Receives incoming messages (text or audio).
• Google Drive Trigger (weekly): Detects new/updated files in the chosen folder for ingestion.

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App credentials required

• WhatsApp Business Cloud (App ID, Token, Phone Number ID)
• OpenAI (Chat + Embeddings)
• Cohere (Rerank)
• Supabase (SUPABASE_URL, ANON_KEY)
• Google Drive (OAuth2) + target Folder ID

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Suggested environment variables

WHATSAPP_APP_ID=
WHATSAPP_TOKEN=
WHATSAPP_PHONE_NUMBER_ID=
OPENAI_API_KEY=
COHERE_API_KEY=
SUPABASE_URL=
SUPABASE_ANON_KEY=
GDRIVE_FOLDER_ID=
RAG_TABLE_NAME="documents"     # table to store vectors/metadata
MAX_ANSWER_WORDS=100            # guardrail for concise replies

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Architecture overview

• Answer-time lane (RAG Tool):

  1. Receive WhatsApp message → 2) Transcribe audio if present → 3) Maintain short-term memory → 4) Retrieve from Supabase vectors (topK) → 5) Rerank with Cohere → 6) Compose ≤100-word reply with sources → 7) Send on WhatsApp.

• Ingest lane (Weekly Sync): A) Detect Drive file updates → B) Download & convert (Docs → text/plain) → C) Chunk (size/overlap) → D) Embed with OpenAI → E) Upsert to Supabase with metadata & hashes.

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How it works (node rundown)

#	Node	Key Inputs	Key Outputs
1	WhatsApp Trigger	Incoming message	Raw WhatsApp payload
2	Switch (Attachment presence/type)	Payload	Route: Text or Audio
3	HTTP Request (Audio path)	attachments[0].data_url	Audio file
4	OpenAI – Translate/ASR	Audio file	Transcribed text
5	Merge	Text path + Audio path	Unified text message
6	Simple Memory	Recent turns	Short-term context
7	OpenAI Chat Model	Prompt + message + memory	Draft answer (tool calls allowed)
8	Supabase Vector Tool (retrieve-as-tool)	Query text, topK=10	Candidate KB passages
9	Cohere Reranker	Candidates	Re-ranked context
10	Send WhatsApp Message	to, body	Reply sent
11	Google Drive Trigger (weekly)	Folder ID, fileUpdated	Changed files
12	Set (File Id)	id from trigger	File ref
13	Google Drive – Download File	Id (Docs→txt)	Raw text
14	Character Text Splitter	chunkSize=2000, overlap=300	Chunks
15	Default Data Loader	Binary→Document	Clean docs
16	OpenAI Embeddings (ingest)	Chunks	Vectors
17	Supabase Vector Store (insert)	Table: documents	Upserted KB

Notes

• The KB Tool is the combo of steps 8–9–7 at answer time (retrieve → rerank → answer).
• The Ingest lane is steps 11–17 (weekly sync of your Drive folder).

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Setup (7‑minute sprint)

1. Import the workflow JSON.

2. Connect credentials: WhatsApp, OpenAI, Cohere, Supabase, Google Drive.

3. Google Drive Trigger: paste your Folder ID; keep fileUpdated event.

4. Download File: ensure Google Docs convert to text/plain.

5. Supabase Vector Store (insert): set table name to documents (or your schema).

6. Character Text Splitter: keep chunkSize=2000, overlap=300 (balanced recall/latency).

7. Retrieve-as-tool: set topK=10 and enable reranker.

8. Send WhatsApp Message mapping:

   • Recipient: {{$("WhatsApp Trigger").item.json.messages[0].from}}
   • Body: {{$json.output}}

9. Test:

   • Send a text and a voice note to your WhatsApp number → confirm concise answers.
   • Drop a Google Doc into the watched folder → verify it’s chunked/embedded on the next weekly poll (or run ingest nodes once manually).

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Prompt, tone & guardrails

• System prompt:

  • Be polite, human, and concise (≤ MAX_ANSWER_WORDS).
  • Cite or reference only the KB content; if unknown, say so and offer to escalate.
  • No prices unless present in the KB. No medical advice.

• Temperature: start at 0.2 for factual replies.

• Memory window: keep a short rolling buffer (e.g., last 4–6 turns).

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Data model (minimum viable)

Table documents (example columns):

• id (uuid)
• source_url (text)
• title (text)
• chunk (text)
• embedding (vector/float[] depending on extension)
• chunk_hash (text)
• updated_at (timestamp)

Indexes

• Unique index on chunk_hash to dedupe
• Index on updated_at for syncs

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Observability & ops

• Log question, selected chunk ids/hashes, and final response to a DB/Sheet for QA.
• Add a low-confidence route (score threshold) → Slack/Telegram escalation to a human.
• Track latency and token usage to tune topK and chunk sizes.

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Customization

• Latency vs quality: try topK=6–8 and chunkSize=1200 for speed.
• Languages: ASR node can be swapped for native multilingual output.
• Escalation: add channel handoff on low confidence or no KB hits.
• Sync cadence: change Drive Trigger to daily if content updates frequently.

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Safety & compliance

• No medical advice. If uncertain or clinical, ask to schedule a consult or refer to the right department.
• PII: Don’t log full phone numbers in plaintext analytics; hash where possible.
• Prices & rates: Only answer if present in the KB; otherwise hand off to front desk.

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Troubleshooting

• No reply sent: Ensure Send message node reads {{$json.output}} (Agent’s response property).
• Audio path failing: Confirm attachments[0].data_url exists and HTTP node fetches a valid file.
• KB not updating: Manually execute the ingest lane; check rows in Supabase.
• Irrelevant answers: Lower temperature to 0.2, increase overlap to 400, and verify Drive docs are clean and structured.

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Categories & tags

• Categories: AI, Customer Support, Healthcare Ops, RAG, WhatsApp
• Tags: WhatsApp, RAG, Google Drive, Supabase, OpenAI, Cohere, Voice Notes

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Pricing (rough, BYO keys)

• n8n: self-host free; n8n.cloud billed by plan.
• OpenAI, Cohere: usage-based by tokens/calls.
• Supabase: free tier + usage; vector storage billed by size.
• WhatsApp Cloud: Meta pricing per conversation.

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Nodes used in workflow

WhatsApp Trigger, Switch, HTTP Request, OpenAI (ASR + Chat + Embeddings), Merge, Simple Memory, Supabase Vector Tool (retrieve), Cohere Reranker, Google Drive Trigger, Set, Google Drive – Download, Character Text Splitter, Default Data Loader.