Fork assistant turns into new drafts (#1788)

* feat(chat): fork assistant turns into new drafts

Builds chat-history attachments on the daemon and routes them into draft composers so users can continue an assistant turn in an existing workspace tab or New Workspace.

* fix(chat): clean up fork draft handling

* fix(chat): address fork draft review feedback

* fix(server): build fork context from bounded timeline

* fix(app): restore assistant turn footer in streams

* fix(app): preserve fork draft setup

* fix(app): tighten assistant fork footers

* fix(app): lock active fork draft handoff

* fix(app): preserve attachment-only draft retries

* fix(app): unify composer attachment scopes

* fix(app): align chat history attachment labels

* fix(app): centralize attachment pill content

* fix(app): trim fork context for workspace naming

packages/client/src/daemon-client.ts

@@ -26,6 +26,7 @@ import type {
   FileUploadResponse,
   FileExplorerResponse,
   FetchAgentTimelineResponseMessage,
+  AgentForkContextResponseMessage,
   GitSetupOptions,
   CheckoutStatusResponse,
   CheckoutCommitResponse,
@@ -456,6 +457,7 @@ type ScheduleUpdatePayload = Extract<
   { type: "schedule/update/response" }
 >["payload"];
 export type FetchAgentTimelinePayload = FetchAgentTimelineResponseMessage["payload"];
+export type AgentForkContextPayload = AgentForkContextResponseMessage["payload"];
 
 export type FetchAgentTimelineDirection = FetchAgentTimelinePayload["direction"];
 export type FetchAgentTimelineProjection = FetchAgentTimelinePayload["projection"];
@@ -502,6 +504,10 @@ function normalizeListCommandsOptions(
   }
   return { agentId: input, ...legacyOptions };
 }
+export interface AgentForkContextOptions {
+  boundaryMessageId?: string;
+  requestId?: string;
+}
 
 type AgentRefreshedStatusPayload = z.infer<typeof AgentRefreshedStatusPayloadSchema>;
 type RestartRequestedStatusPayload = z.infer<typeof RestartRequestedStatusPayloadSchema>;
@@ -2405,6 +2411,41 @@ export class DaemonClient {
     return payload;
   }
 
+  async buildAgentForkContext(
+    agentId: string,
+    options: AgentForkContextOptions = {},
+  ): Promise<AgentForkContextPayload> {
+    const resolvedRequestId = this.createRequestId(options.requestId);
+    const message = SessionInboundMessageSchema.parse({
+      type: "agent.fork_context.request",
+      agentId,
+      requestId: resolvedRequestId,
+      ...(options.boundaryMessageId ? { boundaryMessageId: options.boundaryMessageId } : {}),
+    });
+
+    const payload = await this.sendRequest({
+      requestId: resolvedRequestId,
+      message,
+      timeout: 15000,
+      options: { skipQueue: true },
+      select: (msg) => {
+        if (msg.type !== "agent.fork_context.response") {
+          return null;
+        }
+        if (msg.payload.requestId !== resolvedRequestId) {
+          return null;
+        }
+        return msg.payload;
+      },
+    });
+
+    if (payload.error) {
+      throw new Error(payload.error);
+    }
+
+    return payload;
+  }
+
   // ============================================================================
   // Agent Interaction
   // ============================================================================