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Concepts

Particles

A particle is a single, focused prompt component:

System Prompts

A system prompt combines particles into complete behavior. Each system prompt can include multiple particles, ordered by category (role → tone → guardrails → constraints → format).

Create Particle


Create System Prompt

Compose particles into a complete prompt:
Response includes composed content:

Attach to Model


Versioning

Particles are automatically versioned. Updates create new versions:

Pin Versions

Lock a system prompt to specific particle versions for stability:

Composition Order

Particles are ordered by:
  1. Category priority (fixed): role → tone → guardrails → constraints → format
  2. Order within category (customizable via order field)

Best Practices


FAQ

When should I use particles vs. a single prompt?

Use particles when you have multiple models sharing common behavior (same tone, same guardrails). For simple, one-off assistants, a single prompt via the systemPrompt parameter in the Chat API is fine.

How do I roll back a particle change?

Pin the system prompt to the previous particle version. Particle versions are immutable—nothing is deleted.

Can I override the system prompt at runtime?

Yes. Pass systemPrompt in the Chat API request to override the model’s attached prompt for that specific request.

What’s the max prompt length?

No hard limit, but keep total prompt + context under the model’s context window. Aim for under 2,000 tokens for system prompts.

Models API

Attach prompts to models

Chat API

Override prompts at runtime