feat: add the agent transcript client and hydrated turn and block types used to rehydrate a reopened assistant conversation

web/src/lib/api/client/app/agent/getAgentMessages.ts

@@ -0,0 +1,14 @@
+import type { AgentTranscript } from "@/lib/api/models/app/agent/Agent";
+import Request from "../../Request";
+
+// Loads a session's hydrated transcript so a reopened workspace tab rehydrates
+// its conversation (and any pending approval) from the server.
+export default async function getAgentMessages(
+    sessionId: string,
+): Promise<AgentTranscript> {
+    return await Request<AgentTranscript>({
+        method: "GET",
+        url: `/ai/sessions/${sessionId}/messages`,
+        authorization: true,
+    });
+}

web/src/lib/api/models/app/agent/Agent.ts

@@ -27,6 +27,33 @@ export interface AgentSessionsPage {
     pagination: { next_cursor: string | null; has_more: boolean };
 }
 
+// A persisted transcript block, hydrated server-side into the same shape the
+// live stream renders (see internal/app/aiagent HydratedBlock).
+export interface AgentHydratedBlock {
+    kind: "text" | "tool";
+    text?: string;
+    tool?: string;
+    args_summary?: string;
+    result?: string;
+    entity_type?: string;
+    entity_id?: string;
+    open_url?: string;
+    done: boolean;
+}
+
+export interface AgentHydratedTurn {
+    role: "user" | "assistant";
+    blocks: AgentHydratedBlock[];
+}
+
+// GET /ai/sessions/:id/messages — a reopened session's history + any pending
+// approval, so a tab rehydrates identically to a live run.
+export interface AgentTranscript {
+    title: string;
+    turns: AgentHydratedTurn[];
+    pending: PendingAgentTool | null;
+}
+
 // AgentStreamEvent is one SSE step from a message/approval run.
 export interface AgentStreamEvent {
     type: