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A persona is the core of Whatsy’s intelligence. It tells the local LLM who it is replying as, how that person writes, and what their replies should sound like. A well-crafted persona makes automated replies feel natural and personal; a vague one produces generic-sounding responses that don’t match your style. Spending a few minutes getting the persona right makes a significant difference in quality.

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What goes into a persona

Every persona is made up of four components:
  • Name and description — a label and summary for your own reference (e.g. “The Professional”, “Polite, concise, focused on scheduling”)
  • Tone — a short phrase describing the communication style (e.g. “Formal / Direct”, “Warm / Casual”, “Helpful / Patient”)
  • Writing instructions — a markdown system prompt that describes exactly how you write, what to avoid, and any special rules
  • Example reply pairs — real or representative message exchanges showing an incoming message and the reply you would send

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Creating a persona in the app

1

Open the Personas view

Open the Whatsy app and click Personas in the left sidebar. You’ll see your persona library. Any existing personas are listed here as cards showing their name, status (active or draft), and total chats handled.
2

Create a new persona

Click the + New Persona button in the top-right corner. Whatsy creates a new draft persona and opens the persona editor automatically.
3

Enter a name and description

In the Name field, give the persona a memorable label (e.g. “Out of Office”, “Weekend Mode”). In the Description field, write a one-sentence summary of the persona’s purpose and audience — this is only for your reference.
4

Describe the tone

Fill in the Tone field with a short phrase that captures the communication style. Examples: Casual / Warm, Formal / Direct, Helpful / Patient. This feeds directly into the LLM prompt and shapes the overall register of replies.
5

Write your persona instructions

The System Prompt field is where you describe how you actually write. Be specific — the more detail you give, the better the output. See the example below for a starting point.
6

Add example reply pairs

Scroll to the Example Replies section and click Add to insert a pair. Each pair has an Incoming field (the message someone sends you) and a Reply field (what you would write back). Add at least five pairs to give the model enough signal.
7

Save and activate

Click Save to save the persona as a draft. Review your instructions and examples, then click Set as Active in the editor header to make this the persona Whatsy uses for auto-replies.

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Example persona instructions

Write your system prompt in markdown. Here is a solid starting point you can adapt: 
You are replying as the user in their personal WhatsApp chats. Match their style and tone exactly.

- Write in all lowercase.
- Be warm and natural, not stiff or formal.
- Keep replies short — one to three sentences at most.
- Use emojis sparingly, only when they feel natural.
- Never reveal that you are an AI or an automated system.
- If you don't know the answer to something specific, say you'll follow up later.
- Don't use bullet points or headers in replies — write conversationally.

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Example reply pairs

Include pairs that cover the kinds of messages you actually receive. Here are three examples to illustrate the format:
Incoming messageYour reply
Hey, are you free to catch up this week?yeah for sure! how does thursday afternoon work for you?
When will the report be ready?Should have it over to you by end of day Friday. I’ll ping you when it’s done.
Can you recommend a good plumber?i used a guy called Mike last year — super reliable. want me to dig up his number?
The more specific and varied your examples, the better the LLM can calibrate to your voice. Aim for at least ten pairs that cover different topics and message lengths. Include a mix of short casual replies and slightly longer ones so the model learns when to be brief and when to say more.

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Activating a persona

Only one persona can be active at a time. To switch which persona handles auto-replies, open the persona you want in the editor and click Set as Active. The previously active persona automatically reverts to draft status. The dashboard always shows which persona is currently active.

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Working with multiple personas

You can maintain as many draft personas as you like — for example, a “Vacation Mode” persona for when you’re travelling, a “Professional” persona for business contacts, and a casual one for friends. Switch between them by opening the relevant persona and clicking Set as Active. Use behavior rules to route specific contacts or message types to a particular persona automatically.