---
title: "Universal API"
description: "Feature checklist and normalization rules."
---

## Feature checklist

- [x] Session creation and lifecycle events
- [x] Message streaming (assistant and tool messages)
- [x] Tool call and tool result normalization
- [x] File and image parts
- [x] Human-in-the-loop questions
- [x] Permission prompts and replies
- [x] Plan approval normalization (Claude -> question)
- [x] Event streaming over SSE
- [ ] Persistent storage (out of scope)

## Normalization rules

- **Session ID** is always the client-provided ID.
- **Agent session ID** is surfaced in events but never replaces the primary session ID.
- **Tool calls** map to `UniversalMessagePart::ToolCall` and results to `ToolResult`.
- **File and image parts** map to `AttachmentSource` with `Path`, `Url`, or base64 `Data`.

## Agent mode vs permission mode

- **agentMode**: behavior or system prompt strategy (build/plan/custom).
- **permissionMode**: capability restrictions (default/plan/bypass).

These are separate concepts and must be configured independently.