Arch Tools — Session Create

Use this endpoint when you need to establish a stateful AI session with a configurable model and system prompt before sending a series of messages. Prefer this over direct one-shot AI calls when your workflow requires persistent context, multi-turn conversations, or when you need to scope the AI to a specific persona or role via a system prompt. Especially useful as the first step in an agentic workflow where downstream tools will reference the same session.

• Invalid model name provided — returns 400 with model not supported error
• TTL value out of acceptable range — returns 400 with validation error
• Missing or malformed system prompt — returns 400
• Payment failure or insufficient USDC balance — returns 402
• Session creation quota exceeded — returns 429 rate limit error
• Internal server error during session initialization — returns 500