feat(FN-2441): singularize one-step progress labels

- Update TaskCard step toggle label to render "step" when the unified total is 1
- Update TaskDetailModal completion label to use singular/plural based on total step count
- Add regression tests in TaskCard and TaskDetailModal suites to verify singular labels and reject incorrect plural forms
- Tighten existing completion-count assertions to cover singular/plural text expectations

packages/dashboard/app/components/TaskCard.test.tsx

@@ -113,6 +113,21 @@ describe("TaskCard", () => {
     expect(screen.getByText("5 steps")).toBeDefined();
   });
 
+  it("uses singular step label when unified progress total is one", () => {
+    render(
+      <TaskCard
+        task={makeTask({
+          steps: [{ name: "Step 0", status: "done" }],
+        })}
+        onOpenDetail={noop}
+        addToast={noop}
+      />,
+    );
+
+    expect(screen.getByText("1 step")).toBeDefined();
+    expect(screen.queryByText("1 steps")).toBeNull();
+  });
+
   it("renders workflow checks after normal steps with mapped statuses", () => {
     const { container } = render(
       <TaskCard

packages/dashboard/app/components/TaskCard.tsx

@@ -995,7 +995,7 @@ function TaskCardComponent({
               aria-expanded={showSteps}
               aria-label={showSteps ? "Hide steps" : "Show steps"}
             >
-              <span>{unifiedProgress.total} steps</span>
+              <span>{unifiedProgress.total} step{unifiedProgress.total === 1 ? "" : "s"}</span>
               <ChevronDown
                 size={14}
                 className={`card-steps-toggle-icon${showSteps ? " expanded" : ""}`}

packages/dashboard/app/components/TaskDetailModal.tsx

@@ -1415,7 +1415,7 @@ export function TaskDetailModal({
                   ))}
                 </div>
                 <span className="step-progress-label">
-                  {workingTask.steps.filter(s => s.status === "done").length}/{workingTask.steps.length} steps
+                  {workingTask.steps.filter(s => s.status === "done").length}/{workingTask.steps.length} step{workingTask.steps.length === 1 ? "" : "s"}
                 </span>
               </div>
             ) : (

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

@@ -1563,6 +1563,25 @@ describe("TaskCard steps toggle", () => {
     expect(toggle.textContent).toContain("2 steps");
   });
 
+  it("shows singular step label for one-step tasks", () => {
+    const task = makeTask({
+      column: "todo",
+      steps: [{ name: "Only step", status: "pending" }],
+    });
+
+    render(
+      <TaskCard
+        task={task}
+        onOpenDetail={vi.fn()}
+        addToast={noopToast}
+      />
+    );
+
+    const toggle = screen.getByRole("button", { name: /Show steps/i });
+    expect(toggle.textContent).toContain("1 step");
+    expect(toggle.textContent).not.toContain("1 steps");
+  });
+
   it("clicking toggle expands and shows step list", () => {
     // Use 'todo' column to test default collapsed behavior
     const task = makeTask({

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

@@ -2220,6 +2220,25 @@ describe("TaskDetailModal", () => {
       expect((segments[3] as HTMLElement).style.backgroundColor).toBe("var(--text-dim, #484f58)");
     });
 
+    it("displays singular completion label for one-step tasks", () => {
+      render(
+        <TaskDetailModal
+          task={makeTask({
+            steps: [{ name: "Step 1", status: "done" }],
+          })}
+          onClose={noop}
+          onMoveTask={noopMove}
+          onDeleteTask={noopDelete}
+          onMergeTask={noopMerge}
+          onOpenDetail={noopOpenDetail}
+          addToast={noop}
+        />,
+      );
+
+      expect(screen.getByText("1/1 step")).toBeTruthy();
+      expect(screen.queryByText("1/1 steps")).toBeNull();
+    });
+
     it("displays correct completion count", () => {
       render(
         <TaskDetailModal
@@ -2241,6 +2260,7 @@ describe("TaskDetailModal", () => {
       );
 
       expect(screen.getByText("2/4 steps")).toBeTruthy();
+      expect(screen.queryByText("2/4 step")).toBeNull();
     });
 
     it("has data-tooltip attribute with step name and status on each segment", () => {