Default sub-issues to parent workspace

ui/src/components/NewIssueDialog.test.tsx

@@ -311,12 +311,37 @@ describe("NewIssueDialog", () => {
   });
 
   it("submits parent and goal context for sub-issues", async () => {
+    mockProjectsApi.list.mockResolvedValue([
+      {
+        id: "project-1",
+        name: "Alpha",
+        description: null,
+        archivedAt: null,
+        color: "#445566",
+        executionWorkspacePolicy: {
+          enabled: true,
+          defaultMode: "shared_workspace",
+        },
+      },
+    ]);
+    mockExecutionWorkspacesApi.list.mockResolvedValue([
+      {
+        id: "workspace-1",
+        name: "Parent workspace",
+        status: "active",
+        branchName: "feature/pap-1",
+        cwd: "/tmp/workspace-1",
+        lastUsedAt: new Date("2026-04-06T16:00:00.000Z"),
+      },
+    ]);
+    mockInstanceSettingsApi.getExperimental.mockResolvedValue({ enableIsolatedWorkspaces: true });
     dialogState.newIssueDefaults = {
       parentId: "issue-1",
       parentIdentifier: "PAP-1",
       parentTitle: "Parent issue",
       title: "Child issue",
       projectId: "project-1",
+      executionWorkspaceId: "workspace-1",
       goalId: "goal-1",
     };
 
@@ -340,9 +365,75 @@ describe("NewIssueDialog", () => {
         parentId: "issue-1",
         goalId: "goal-1",
         projectId: "project-1",
+        executionWorkspaceId: "workspace-1",
       }),
     );
 
     act(() => root.unmount());
   });
+
+  it("warns when a sub-issue stops matching the parent workspace", async () => {
+    mockProjectsApi.list.mockResolvedValue([
+      {
+        id: "project-1",
+        name: "Alpha",
+        description: null,
+        archivedAt: null,
+        color: "#445566",
+        executionWorkspacePolicy: {
+          enabled: true,
+          defaultMode: "shared_workspace",
+        },
+      },
+    ]);
+    mockExecutionWorkspacesApi.list.mockResolvedValue([
+      {
+        id: "workspace-1",
+        name: "Parent workspace",
+        status: "active",
+        branchName: "feature/pap-1",
+        cwd: "/tmp/workspace-1",
+        lastUsedAt: new Date("2026-04-06T16:00:00.000Z"),
+      },
+      {
+        id: "workspace-2",
+        name: "Other workspace",
+        status: "active",
+        branchName: "feature/pap-2",
+        cwd: "/tmp/workspace-2",
+        lastUsedAt: new Date("2026-04-06T16:01:00.000Z"),
+      },
+    ]);
+    mockInstanceSettingsApi.getExperimental.mockResolvedValue({ enableIsolatedWorkspaces: true });
+    dialogState.newIssueDefaults = {
+      parentId: "issue-1",
+      parentIdentifier: "PAP-1",
+      parentTitle: "Parent issue",
+      title: "Child issue",
+      projectId: "project-1",
+      executionWorkspaceId: "workspace-1",
+      parentExecutionWorkspaceLabel: "Parent workspace",
+      goalId: "goal-1",
+    };
+
+    const { root } = renderDialog(container);
+    await flush();
+
+    expect(container.textContent).not.toContain("will no longer use the parent issue workspace");
+
+    const selects = Array.from(container.querySelectorAll("select"));
+    const modeSelect = selects[0] as HTMLSelectElement | undefined;
+    expect(modeSelect).not.toBeUndefined();
+
+    await act(async () => {
+      modeSelect!.value = "shared_workspace";
+      modeSelect!.dispatchEvent(new Event("change", { bubbles: true }));
+    });
+    await flush();
+
+    expect(container.textContent).toContain("will no longer use the parent issue workspace");
+    expect(container.textContent).toContain("Parent workspace");
+
+    act(() => root.unmount());
+  });
 });

ui/src/components/NewIssueDialog.tsx

@@ -301,6 +301,8 @@ export function NewIssueDialog() {
   const isSubIssueMode = Boolean(newIssueDefaults.parentId);
   const parentIssueLabel = newIssueDefaults.parentIdentifier
     ?? (newIssueDefaults.parentId ? newIssueDefaults.parentId.slice(0, 8) : "");
+  const parentExecutionWorkspaceId = newIssueDefaults.executionWorkspaceId ?? "";
+  const parentExecutionWorkspaceLabel = newIssueDefaults.parentExecutionWorkspaceLabel ?? parentExecutionWorkspaceId;
 
   // Popover states
   const [statusOpen, setStatusOpen] = useState(false);
@@ -517,18 +519,23 @@ export function NewIssueDialog() {
     if (newIssueDefaults.parentId) {
       const defaultProjectId = newIssueDefaults.projectId ?? "";
       const defaultProject = orderedProjects.find((project) => project.id === defaultProjectId);
+      const defaultProjectWorkspaceId = newIssueDefaults.projectWorkspaceId
+        ?? defaultProjectWorkspaceIdForProject(defaultProject);
+      const defaultExecutionWorkspaceMode = newIssueDefaults.executionWorkspaceId
+        ? "reuse_existing"
+        : (newIssueDefaults.executionWorkspaceMode ?? defaultExecutionWorkspaceModeForProject(defaultProject));
       setTitle(newIssueDefaults.title ?? "");
       setDescription(newIssueDefaults.description ?? "");
       setStatus(newIssueDefaults.status ?? "todo");
       setPriority(newIssueDefaults.priority ?? "");
       setProjectId(defaultProjectId);
-      setProjectWorkspaceId(defaultProjectWorkspaceIdForProject(defaultProject));
+      setProjectWorkspaceId(defaultProjectWorkspaceId);
       setAssigneeValue(assigneeValueFromSelection(newIssueDefaults));
       setAssigneeModelOverride("");
       setAssigneeThinkingEffort("");
       setAssigneeChrome(false);
-      setExecutionWorkspaceMode(defaultExecutionWorkspaceModeForProject(defaultProject));
+      setExecutionWorkspaceMode(defaultExecutionWorkspaceMode);
-      setSelectedExecutionWorkspaceId("");
+      setSelectedExecutionWorkspaceId(newIssueDefaults.executionWorkspaceId ?? "");
       executionWorkspaceDefaultProjectId.current = defaultProjectId || null;
     } else if (newIssueDefaults.title) {
       setTitle(newIssueDefaults.title);
@@ -797,6 +804,13 @@ export function NewIssueDialog() {
   const selectedReusableExecutionWorkspace = deduplicatedReusableWorkspaces.find(
     (workspace) => workspace.id === selectedExecutionWorkspaceId,
   );
+  const isUsingParentExecutionWorkspace = isSubIssueMode && parentExecutionWorkspaceId
+    ? executionWorkspaceMode === "reuse_existing" && selectedExecutionWorkspaceId === parentExecutionWorkspaceId
+    : false;
+  const showParentWorkspaceWarning = isSubIssueMode
+    && currentProjectSupportsExecutionWorkspace
+    && Boolean(parentExecutionWorkspaceId)
+    && !isUsingParentExecutionWorkspace;
   const assigneeOptionsTitle =
     assigneeAdapterType === "claude_local"
       ? "Claude options"
@@ -1202,6 +1216,11 @@ export function NewIssueDialog() {
                   Reusing {selectedReusableExecutionWorkspace.name} from {selectedReusableExecutionWorkspace.branchName ?? selectedReusableExecutionWorkspace.cwd ?? "existing execution workspace"}.
                 </div>
               )}
+              {showParentWorkspaceWarning ? (
+                <div className="rounded-md border border-amber-300/60 bg-amber-50 px-2 py-1.5 text-[11px] text-amber-900 dark:border-amber-800/70 dark:bg-amber-950/30 dark:text-amber-100">
+                  Warning: this sub-issue will no longer use the parent issue workspace{parentExecutionWorkspaceLabel ? ` (${parentExecutionWorkspaceLabel})` : ""}.
+                </div>
+              ) : null}
             </div>
           </div>
         )}

ui/src/context/DialogContext.tsx

@@ -4,10 +4,14 @@ interface NewIssueDefaults {
   status?: string;
   priority?: string;
   projectId?: string;
+  projectWorkspaceId?: string;
   goalId?: string;
   parentId?: string;
   parentIdentifier?: string;
   parentTitle?: string;
+  executionWorkspaceId?: string;
+  executionWorkspaceMode?: string;
+  parentExecutionWorkspaceLabel?: string;
   assigneeAgentId?: string;
   assigneeUserId?: string;
   title?: string;

ui/src/pages/IssueDetail.tsx

@@ -507,9 +507,31 @@ export function IssueDetail() {
       parentIdentifier: issue.identifier ?? undefined,
       parentTitle: issue.title,
       projectId: issue.projectId ?? undefined,
+      projectWorkspaceId: issue.projectWorkspaceId ?? undefined,
       goalId: issue.goalId ?? undefined,
+      executionWorkspaceId: issue.executionWorkspaceId ?? undefined,
+      executionWorkspaceMode: issue.executionWorkspaceId ? "reuse_existing" : issue.executionWorkspacePreference ?? undefined,
+      parentExecutionWorkspaceLabel:
+        issue.currentExecutionWorkspace?.name
+          ?? issue.currentExecutionWorkspace?.branchName
+          ?? issue.currentExecutionWorkspace?.cwd
+          ?? issue.executionWorkspaceId
+          ?? undefined,
     });
-  }, [issue?.goalId, issue?.id, issue?.identifier, issue?.projectId, issue?.title, openNewIssue]);
+  }, [
+    issue?.currentExecutionWorkspace?.branchName,
+    issue?.currentExecutionWorkspace?.cwd,
+    issue?.currentExecutionWorkspace?.name,
+    issue?.executionWorkspaceId,
+    issue?.executionWorkspacePreference,
+    issue?.goalId,
+    issue?.id,
+    issue?.identifier,
+    issue?.projectId,
+    issue?.projectWorkspaceId,
+    issue?.title,
+    openNewIssue,
+  ]);
 
   const commentReassignOptions = useMemo(() => {
     const options: Array<{ id: string; label: string; searchText?: string }> = [];