Session update union type.

A SessionUpdate can be one of several variants, discriminated by the type field:

• "user_message_chunk" - Streaming user message content
• "agent_message_chunk" - Streaming agent response content
• "agent_thought_chunk" - Streaming agent reasoning content
• "tool_call" - Notification of a new tool call
• "tool_call_update" - Status update for an existing tool call
• "plan" - Agent's execution plan for complex tasks
• "available_commands_update" - Changes in available commands
• "current_mode_update" - Session mode changes

Usage

You can use any of the variant structs directly:

# User message chunk
%ACPex.Schema.Types.SessionUpdate.UserMessageChunk{
  session_update: "update-123",
  content: %{"type" => "text", "text" => "Hello"}
}

# Tool call
%ACPex.Schema.Types.SessionUpdate.ToolCall{
  session_update: "update-456",
  tool_call_id: "tool-789",
  title: "Read File",
  status: "running"
}

Or use maps (which will be validated at runtime):

%{
  "type" => "user_message_chunk",
  "sessionUpdate" => "update-123",
  "content" => %{"type" => "text", "text" => "Hello"}
}

Decoding from JSON

Use the decode/1 function to decode JSON into the appropriate variant struct:

json = ~s({"type":"user_message_chunk","sessionUpdate":"u1","content":{"type":"text","text":"Hi"}})
{:ok, %ACPex.Schema.Types.SessionUpdate.UserMessageChunk{}} = SessionUpdate.decode(json)

Encoding to JSON

All variant structs implement Jason.Encoder:

update = %ACPex.Schema.Types.SessionUpdate.UserMessageChunk{
  session_update: "u1",
  content: %{"type" => "text", "text" => "Hi"}
}
Jason.encode!(update)