refactor(sdk): unify message types with pi-ai source of truth

Replace hand-written message/content types in @multica/sdk with
`import type` from @mariozechner/pi-ai and @mariozechner/pi-agent-core.
This ensures compile-time correctness and eliminates type drift between
backend and frontend (e.g. "tool_use" vs "toolCall", "tool_result" vs
"toolResult").

- stream.ts: re-export TextContent, ThinkingContent, ToolCall,
  ImageContent from pi-ai; use AgentEvent from pi-agent-core
- rpc.ts: AgentMessageItem = pi-ai Message (no more manual mirroring)
- connection-store.ts: use SDK types instead of inline hand-written ones
- ContentBlock now includes ImageContent to match backend reality

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

packages/sdk/src/actions/index.ts

@@ -33,8 +33,15 @@ export {
 export {
   StreamAction,
   type StreamPayload,
-  type StreamEvent,
-  type StreamMessageEvent,
-  type StreamToolEvent,
+  type AgentEvent,
+  type ContentBlock,
+  type TextContent,
+  type ThinkingContent,
+  type ToolCall,
+  type ImageContent,
+  // Backward-compatible aliases
+  type TextBlock,
+  type ThinkingBlock,
+  type ToolCallBlock,
   extractTextFromEvent,
 } from "./stream";

packages/sdk/src/actions/rpc.ts

@@ -1,5 +1,7 @@
 /** RPC Actions - 请求/响应模式 */
 
+import type { Message } from "@mariozechner/pi-ai";
+
 export const RequestAction = "request" as const;
 export const ResponseAction = "response" as const;
 
@@ -65,34 +67,11 @@ export interface GetAgentMessagesParams {
   limit?: number;
 }
 
-/** Content block types from the agent engine */
-export interface TextContentBlock {
-  type: "text";
-  text: string;
-}
-
-export interface ThinkingContentBlock {
-  type: "thinking";
-  thinking: string;
-}
-
-export interface ToolCallBlock {
-  type: "tool_use";
-  id: string;
-  name: string;
-  input: unknown;
-}
-
-export interface ImageContentBlock {
-  type: "image";
-  url: string;
-}
-
-/** Agent message returned by getAgentMessages (mirrors pi-ai Message) */
-export type AgentMessageItem =
-  | { role: "user"; content: string | (TextContentBlock | ImageContentBlock)[]; timestamp: number }
-  | { role: "assistant"; content: (TextContentBlock | ThinkingContentBlock | ToolCallBlock)[]; timestamp: number }
-  | { role: "tool_result"; toolCallId: string; content: (TextContentBlock | ImageContentBlock)[]; isError: boolean; timestamp: number }
+/**
+ * Agent message returned by getAgentMessages.
+ * This is pi-ai's Message type — the backend returns it as-is from SessionManager.loadMessages().
+ */
+export type AgentMessageItem = Message;
 
 /** getAgentMessages - response payload */
 export interface GetAgentMessagesResult {

packages/sdk/src/actions/stream.ts

@@ -1,49 +1,47 @@
-/** Stream Action - 流式消息传输 */
+/** Stream Action */
 
 export const StreamAction = "stream" as const;
 
+// --- Content block types (re-exported from pi-ai, the single source of truth) ---
+
+import type {
+  TextContent,
+  ThinkingContent,
+  ToolCall,
+  ImageContent,
+} from "@mariozechner/pi-ai";
+import type { AgentEvent } from "@mariozechner/pi-agent-core";
+
+export type { TextContent, ThinkingContent, ToolCall, ImageContent };
+export type { AgentEvent };
+
+/** Backward-compatible aliases */
+export type TextBlock = TextContent;
+export type ThinkingBlock = ThinkingContent;
+export type ToolCallBlock = ToolCall;
+export type ContentBlock = TextContent | ThinkingContent | ToolCall | ImageContent;
+
+// --- Stream event types ---
+
 /**
- * AgentEvent types forwarded by the Hub to frontend clients.
- * These mirror the subset of AgentEvent from @mariozechner/pi-agent-core
- * that the Hub forwards (filtered at the Hub layer).
+ * Hub forwards AgentEvent from pi-agent-core as-is.
+ * StreamPayload wraps it with routing metadata.
  */
-export interface StreamMessageEvent {
-  type: "message_start" | "message_update" | "message_end";
-  message: {
-    id?: string;
-    role: string;
-    content?: Array<{ type: string; text?: string }>;
-  };
-  assistantMessageEvent?: unknown;
-}
-
-export interface StreamToolEvent {
-  type: "tool_execution_start" | "tool_execution_end";
-  toolCallId: string;
-  toolName: string;
-  args?: unknown;
-  result?: unknown;
-  isError?: boolean;
-}
-
-export type StreamEvent = StreamMessageEvent | StreamToolEvent;
-
-/** 流消息 payload — wraps a raw AgentEvent with stream/agent identifiers */
 export interface StreamPayload {
-  /** 流 ID，关联同一个流的所有消息 */
   streamId: string;
-  /** 所属 agent ID */
   agentId: string;
-  /** Raw agent event from the engine */
-  event: StreamEvent;
+  event: AgentEvent;
 }
 
-/** Extract plain text from an AgentMessage content array */
-export function extractTextFromEvent(event: StreamMessageEvent): string {
-  const content = event.message?.content;
+/** Extract plain text from an AgentEvent that carries a message */
+export function extractTextFromEvent(event: AgentEvent): string {
+  if (!("message" in event)) return "";
+  const msg = event.message;
+  if (!msg || !("content" in msg)) return "";
+  const content = msg.content;
   if (!Array.isArray(content)) return "";
   return content
-    .filter((c) => c.type === "text")
+    .filter((c): c is TextContent => c.type === "text")
     .map((c) => c.text ?? "")
     .join("");
 }