fix: reserve and clear task worktrees correctly

packages/dashboard/src/routes.test.ts

@@ -701,10 +701,10 @@ describe("POST /tasks/:id/retry", () => {
 
     expect(res.status).toBe(200);
     expect(store.updateTask).toHaveBeenCalledWith("KB-001", {
-      status: undefined,
-      error: undefined,
-      worktree: undefined,
-      branch: undefined,
+      status: null,
+      error: null,
+      worktree: null,
+      branch: null,
     });
     expect(store.moveTask).toHaveBeenCalledWith("KB-001", "todo");
   });
@@ -734,10 +734,10 @@ describe("POST /tasks/:id/retry", () => {
 
     expect(res.status).toBe(200);
     expect(store.updateTask).toHaveBeenCalledWith("KB-001", {
-      status: undefined,
-      error: undefined,
-      worktree: undefined,
-      branch: undefined,
+      status: null,
+      error: null,
+      worktree: null,
+      branch: null,
     });
     expect(store.moveTask).toHaveBeenCalledWith("KB-001", "todo");
   });
@@ -755,10 +755,10 @@ describe("POST /tasks/:id/retry", () => {
 
     expect(res.status).toBe(200);
     expect(store.updateTask).toHaveBeenCalledWith("KB-001", {
-      status: undefined,
-      error: undefined,
-      worktree: undefined,
-      branch: undefined,
+      status: null,
+      error: null,
+      worktree: null,
+      branch: null,
     });
     expect(store.moveTask).toHaveBeenCalledWith("KB-001", "todo");
     expect(store.logEntry).toHaveBeenCalledWith("KB-001", "Retry requested from dashboard");

packages/dashboard/src/routes.ts

@@ -1794,10 +1794,10 @@ export function createApiRoutes(store: TaskStore, options?: ServerOptions): Rout
         return;
       }
       await scopedStore.updateTask(req.params.id, {
-        status: undefined,
-        error: undefined,
-        worktree: undefined,
-        branch: undefined,
+        status: null,
+        error: null,
+        worktree: null,
+        branch: null,
       });
       await scopedStore.logEntry(req.params.id, "Retry requested from dashboard");
       const updated = await scopedStore.moveTask(req.params.id, "todo");