fix(FN-845): fix comment state propagation in dashboard modal

- Fix comment display state not propagating correctly in TaskDetailModal
- Remove unused AgentListModal and AgentsView components and their tests
- Simplify GitManagerModal by removing unused code paths
- Remove dead CSS styles from dashboard stylesheet
- Update README docs to clarify comment display behavior
- Add tests for TaskDetailModal comment state handling

packages/dashboard/app/App.tsx

@@ -638,6 +638,7 @@ function AppInner() {
           onMergeTask={mergeTask}
           onRetryTask={retryTask}
           onDuplicateTask={duplicateTask}
+          onTaskUpdated={(updated) => setDetailTask(prev => prev ? { ...prev, ...updated } : prev)}
           addToast={addToast}
           githubTokenConfigured={githubTokenConfigured}
         />

packages/dashboard/app/components/TaskDetailModal.tsx

@@ -125,6 +125,7 @@ interface TaskDetailModalProps {
   onMergeTask: (id: string) => Promise<MergeResult>;
   onRetryTask?: (id: string) => Promise<Task>;
   onDuplicateTask?: (id: string) => Promise<Task>;
+  onTaskUpdated?: (task: Task) => void;
   addToast: (message: string, type?: ToastType) => void;
   githubTokenConfigured?: boolean;
 }
@@ -146,6 +147,7 @@ export function TaskDetailModal({
   onMergeTask,
   onRetryTask,
   onDuplicateTask,
+  onTaskUpdated,
   addToast,
   githubTokenConfigured,
 }: TaskDetailModalProps) {
@@ -827,7 +829,7 @@ export function TaskDetailModal({
           ) : activeTab === "commits" ? (
             <CommitDiffTab commitSha={task.mergeDetails?.commitSha ?? ""} mergeDetails={task.mergeDetails} />
           ) : activeTab === "comments" ? (
-            <TaskComments task={task} addToast={addToast} projectId={projectId} />
+            <TaskComments task={task} addToast={addToast} projectId={projectId} onTaskUpdated={onTaskUpdated} />
           ) : (
           <>
           {/* Summary section - only for done tasks with summary */}

packages/dashboard/app/components/__tests__/TaskDetailModal.test.tsx

@@ -14,6 +14,7 @@ vi.mock("../../api", () => ({
   rejectPlan: vi.fn().mockResolvedValue({}),
   duplicateTask: vi.fn().mockResolvedValue({}),
   refineTask: vi.fn().mockResolvedValue({}),
+  addSteeringComment: vi.fn(),
   // TaskForm dependencies
   fetchModels: vi.fn().mockResolvedValue({ models: [], favoriteProviders: [] }),
   fetchSettings: vi.fn().mockResolvedValue({ modelPresets: [], autoSelectModelPreset: false, defaultPresetBySize: {} }),
@@ -3439,6 +3440,74 @@ describe("TaskDetailModal", () => {
     });
   });
 
+  describe("comment state propagation (FN-845)", () => {
+    it("passes onTaskUpdated to TaskComments when provided", async () => {
+      const { addSteeringComment } = await import("../../api");
+      const onTaskUpdated = vi.fn();
+      const updatedTask = makeTask({
+        comments: [{ id: "c1", text: "New comment", author: "user", createdAt: "2026-01-01T00:00:00.000Z" }],
+      });
+      vi.mocked(addSteeringComment).mockResolvedValueOnce(updatedTask);
+
+      render(
+        <TaskDetailModal
+          task={makeTask()}
+          onClose={noop}
+          onMoveTask={noopMove}
+          onDeleteTask={noopDelete}
+          onMergeTask={noopMerge}
+          onOpenDetail={noopOpenDetail}
+          onTaskUpdated={onTaskUpdated}
+          addToast={noop}
+        />,
+      );
+
+      // Switch to Comments tab
+      fireEvent.click(screen.getByText("Comments"));
+
+      // Add a comment
+      fireEvent.change(screen.getByPlaceholderText(/Add a comment/), { target: { value: "New comment" } });
+      fireEvent.click(screen.getByText("Add Comment"));
+
+      await waitFor(() => {
+        expect(addSteeringComment).toHaveBeenCalledWith("FN-099", "New comment", undefined);
+        expect(onTaskUpdated).toHaveBeenCalledWith(updatedTask);
+      });
+    });
+
+    it("comment mutations still work when onTaskUpdated is not provided", async () => {
+      const { addSteeringComment } = await import("../../api");
+      const addToast = vi.fn();
+      vi.mocked(addSteeringComment).mockResolvedValueOnce(makeTask({
+        comments: [{ id: "c1", text: "Hello", author: "user", createdAt: "2026-01-01T00:00:00.000Z" }],
+      }));
+
+      render(
+        <TaskDetailModal
+          task={makeTask()}
+          onClose={noop}
+          onMoveTask={noopMove}
+          onDeleteTask={noopDelete}
+          onMergeTask={noopMerge}
+          onOpenDetail={noopOpenDetail}
+          addToast={addToast}
+        />,
+      );
+
+      // Switch to Comments tab
+      fireEvent.click(screen.getByText("Comments"));
+
+      // Add a comment — should succeed without error even without onTaskUpdated
+      fireEvent.change(screen.getByPlaceholderText(/Add a comment/), { target: { value: "Hello" } });
+      fireEvent.click(screen.getByText("Add Comment"));
+
+      await waitFor(() => {
+        expect(addSteeringComment).toHaveBeenCalledWith("FN-099", "Hello", undefined);
+        expect(addToast).toHaveBeenCalledWith("Comment added", "success");
+      });
+    });
+  });
+
   describe("Workflow step ordering in edit mode (FN-836)", () => {
     it("sends ordered enabledWorkflowSteps when saving with reordered steps", async () => {
       const { updateTask, fetchWorkflowSteps } = await import("../../api");