Fix Foundry handoff creation flow

factory/packages/backend/src/actors/handoff/index.ts

@@ -51,6 +51,7 @@ export interface HandoffInput {
   agentType: AgentType | null;
   explicitTitle: string | null;
   explicitBranchName: string | null;
+  initialPrompt: string | null;
 }
 
 interface InitializeCommand {
@@ -129,6 +130,7 @@ export const handoff = actor({
     agentType: input.agentType,
     explicitTitle: input.explicitTitle,
     explicitBranchName: input.explicitBranchName,
+    initialPrompt: input.initialPrompt,
     initialized: false,
     previousStatus: null as string | null,
   }),

factory/packages/backend/src/actors/handoff/workflow/init.ts

@@ -413,7 +413,10 @@ export async function initCreateSessionActivity(
       : undefined;
 
   return await sandboxInstance.createSession({
-    prompt: buildAgentPrompt(loopCtx.state.task),
+    prompt:
+      typeof loopCtx.state.initialPrompt === "string"
+        ? loopCtx.state.initialPrompt
+        : buildAgentPrompt(loopCtx.state.task),
     cwd,
     agent: (loopCtx.state.agentType ?? config.default_agent) as any
   });

factory/packages/backend/src/actors/project/actions.ts

@@ -43,6 +43,7 @@ interface CreateHandoffCommand {
   agentType: AgentType | null;
   explicitTitle: string | null;
   explicitBranchName: string | null;
+  initialPrompt: string | null;
   onBranch: string | null;
 }
 
@@ -387,7 +388,8 @@ async function createHandoffMutation(c: any, cmd: CreateHandoffCommand): Promise
       providerId: cmd.providerId,
       agentType: cmd.agentType,
       explicitTitle: onBranch ? null : cmd.explicitTitle,
-      explicitBranchName: onBranch ? null : cmd.explicitBranchName
+      explicitBranchName: onBranch ? null : cmd.explicitBranchName,
+      initialPrompt: cmd.initialPrompt,
     });
   } catch (error) {
     if (onBranch) {

factory/packages/backend/src/actors/workspace/actions.ts

@@ -295,6 +295,7 @@ async function createHandoffMutation(c: any, input: CreateHandoffInput): Promise
     agentType: input.agentType ?? null,
     explicitTitle: input.explicitTitle ?? null,
     explicitBranchName: input.explicitBranchName ?? null,
+    initialPrompt: input.initialPrompt ?? null,
     onBranch: input.onBranch ?? null
   });
 
@@ -312,9 +313,10 @@ async function createHandoffMutation(c: any, input: CreateHandoffInput): Promise
 
   const handoff = getHandoff(c, c.state.workspaceId, repoId, created.handoffId);
   await handoff.provision({ providerId });
+  const provisioned = await handoff.get();
 
   await workspaceActions.notifyWorkbenchUpdated(c);
-  return created;
+  return provisioned;
 }
 
 async function refreshProviderProfilesMutation(c: any, command?: RefreshProviderProfilesCommand): Promise<void> {
@@ -440,16 +442,20 @@ export const workspaceActions = {
     c.broadcast("workbenchUpdated", { at: Date.now() });
   },
 
-  async createWorkbenchHandoff(c: any, input: HandoffWorkbenchCreateHandoffInput): Promise<{ handoffId: string }> {
+  async createWorkbenchHandoff(c: any, input: HandoffWorkbenchCreateHandoffInput): Promise<{ handoffId: string; tabId?: string }> {
     const created = await workspaceActions.createHandoff(c, {
       workspaceId: c.state.workspaceId,
       repoId: input.repoId,
       task: input.task,
       ...(input.title ? { explicitTitle: input.title } : {}),
       ...(input.branch ? { explicitBranchName: input.branch } : {}),
+      ...(input.initialPrompt !== undefined ? { initialPrompt: input.initialPrompt } : {}),
       ...(input.model ? { agentType: agentTypeForModel(input.model) } : {})
     });
-    return { handoffId: created.handoffId };
+    return {
+      handoffId: created.handoffId,
+      ...(created.activeSessionId ? { tabId: created.activeSessionId } : {}),
+    };
   },
 
   async markWorkbenchUnread(c: any, input: HandoffWorkbenchSelectInput): Promise<void> {