feat(FN-4613): complete Step 3 — guard acceptance visibility regressions

Fusion-Task-Id: FN-4613
Fusion-Task-Lineage: 07ecbe9c-cfee-42d8-b9d2-8b99b2cce9e6

packages/dashboard/app/components/MissionManager.tsx

@@ -824,30 +824,56 @@ export function MissionManager({ isOpen, isInline = false, onClose, addToast, pr
         return;
       }
       setSelectedMission(data);
-      // Auto-expand first milestone and slice
       if (data.milestones.length > 0) {
         const firstMilestoneId = data.milestones[0].id;
-        setSelectedMilestoneId(firstMilestoneId);
+        const milestoneIds = new Set(data.milestones.map((milestone) => milestone.id));
+        const selectedMilestoneStillExists = selectedMilestoneIdRef.current
+          && milestoneIds.has(selectedMilestoneIdRef.current);
+        const nextSelectedMilestoneId = selectedMilestoneStillExists
+          ? selectedMilestoneIdRef.current
+          : firstMilestoneId;
+
+        setSelectedMilestoneId(nextSelectedMilestoneId);
         setValidationRoundsExpanded(true);
-        setExpandedMilestones(new Set([firstMilestoneId]));
+
-        // Load assertions and validation rollup for the first milestone (inline to avoid forward ref)
+        // FN-4613: preserve user-expanded milestones/slices across refetch instead of resetting to first-only.
-        fetchAssertions(firstMilestoneId, projectId).then((assertions) => {
+        setExpandedMilestones((prev) => {
+          const next = new Set(Array.from(prev).filter((milestoneId) => milestoneIds.has(milestoneId)));
+          next.add(nextSelectedMilestoneId);
+          return next;
+        });
+
+        const availableSliceIds = new Set(
+          data.milestones.flatMap((milestone) => milestone.slices.map((slice) => slice.id)),
+        );
+        const selectedMilestone = data.milestones.find((milestone) => milestone.id === nextSelectedMilestoneId);
+        const selectedMilestoneFirstSliceId = selectedMilestone?.slices[0]?.id ?? null;
+        setExpandedSlices((prev) => {
+          const next = new Set(Array.from(prev).filter((sliceId) => availableSliceIds.has(sliceId)));
+          if (selectedMilestoneFirstSliceId) {
+            const hasExpandedSliceForSelectedMilestone = selectedMilestone?.slices.some((slice) => next.has(slice.id)) ?? false;
+            if (!hasExpandedSliceForSelectedMilestone) {
+              next.add(selectedMilestoneFirstSliceId);
+            }
+          }
+          return next;
+        });
+
+        // Load assertions and validation rollup for the selected milestone.
+        fetchAssertions(nextSelectedMilestoneId, projectId).then((assertions) => {
           setAssertionsByMilestone((prev) => {
             const next = new Map(prev);
-            next.set(firstMilestoneId, assertions);
+            next.set(nextSelectedMilestoneId, assertions);
             return next;
           });
         }).catch(() => { /* silently fail */ });
-        fetchMilestoneValidation(firstMilestoneId, projectId).then((rollup) => {
+        fetchMilestoneValidation(nextSelectedMilestoneId, projectId).then((rollup) => {
           setValidationRollupByMilestone((prev) => {
             const next = new Map(prev);
-            next.set(firstMilestoneId, rollup);
+            next.set(nextSelectedMilestoneId, rollup);
             return next;
           });
         }).catch(() => { /* silently fail */ });
-        if (data.milestones[0].slices.length > 0) {
-          setExpandedSlices(new Set([data.milestones[0].slices[0].id]));
-        }
       } else {
         setSelectedMilestoneId(null);
         setValidationTelemetry(null);
@@ -898,6 +924,18 @@ export function MissionManager({ isOpen, isInline = false, onClose, addToast, pr
 
   useEffect(() => {
     setValidationRoundsExpanded(true);
+    if (!selectedMilestoneId) {
+      return;
+    }
+    // FN-4613: selecting a milestone from any navigation path keeps its acceptance criteria visible.
+    setExpandedMilestones((prev) => {
+      if (prev.has(selectedMilestoneId)) {
+        return prev;
+      }
+      const next = new Set(prev);
+      next.add(selectedMilestoneId);
+      return next;
+    });
   }, [selectedMilestoneId]);
 
   const refreshValidationTelemetry = useCallback((milestoneId: string) => {

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

@@ -4234,6 +4234,127 @@ describe("MissionManager", () => {
     });
   });
 
+  describe("FN-4613: persisted acceptance criteria visibility", () => {
+    const createFn4613MissionDetail = () => {
+      const missionDetail = JSON.parse(JSON.stringify(mockMissionDetail)) as typeof mockMissionDetail;
+      missionDetail.milestones = [
+        {
+          ...missionDetail.milestones[0],
+          id: "MS-001",
+          title: "Milestone One",
+          acceptanceCriteria: "",
+          slices: [
+            {
+              ...missionDetail.milestones[0].slices[0],
+              id: "SL-001",
+              title: "Slice One",
+              features: [
+                {
+                  ...missionDetail.milestones[0].slices[0].features[0],
+                  id: "F-001",
+                  title: "Feature One",
+                  acceptanceCriteria: "",
+                },
+              ],
+            },
+          ],
+        },
+        {
+          ...missionDetail.milestones[0],
+          id: "MS-002",
+          title: "Milestone Two",
+          acceptanceCriteria: "Milestone two acceptance criteria",
+          slices: [
+            {
+              ...missionDetail.milestones[0].slices[0],
+              id: "SL-002",
+              title: "Slice Two",
+              milestoneId: "MS-002",
+              features: [
+                {
+                  ...missionDetail.milestones[0].slices[0].features[0],
+                  id: "F-002",
+                  title: "Feature Two",
+                  sliceId: "SL-002",
+                  acceptanceCriteria: "Feature two acceptance criteria",
+                },
+              ],
+            },
+          ],
+        },
+      ];
+      return missionDetail;
+    };
+
+    it("keeps non-first milestone acceptance discoverable on initial load", async () => {
+      globalThis.fetch = createDetailFetchMockForMissionDetail(createFn4613MissionDetail());
+      render(<MissionManager isOpen={true} onClose={vi.fn()} addToast={vi.fn()} />);
+
+      fireEvent.click(await screen.findByText("Build Auth System"));
+      await waitForDetailLoaded("Milestone One");
+
+      fireEvent.click(screen.getByText("Milestone Two"));
+      expect(screen.getByText("Milestone two acceptance criteria", { exact: false })).toBeInTheDocument();
+    });
+
+    it("preserves expanded non-first milestone after mission detail refetch", async () => {
+      globalThis.EventSource = MockEventSource as unknown as typeof globalThis.EventSource;
+      const missionDetail = createFn4613MissionDetail();
+      const fetchMock = createDetailFetchMockForMissionDetail(missionDetail);
+      globalThis.fetch = fetchMock;
+      render(<MissionManager isOpen={true} onClose={vi.fn()} addToast={vi.fn()} />);
+
+      fireEvent.click(await screen.findByText("Build Auth System"));
+      await waitForDetailLoaded("Milestone One");
+
+      fireEvent.click(screen.getByText("Milestone Two"));
+      await waitFor(() => {
+        expect(screen.getByText("Milestone two acceptance criteria", { exact: false })).toBeInTheDocument();
+      });
+
+      await act(async () => {
+        for (const source of MockEventSource.instances) {
+          source.emit("mission:updated", { id: "M-001", title: "Build Auth System", status: "active" });
+        }
+      });
+
+      await waitFor(() => {
+        expect(screen.getByText("Milestone two acceptance criteria", { exact: false })).toBeInTheDocument();
+      });
+      expect(fetchMock.mock.calls.filter((call) => String(call[0]).includes("/api/missions/M-001")).length).toBeGreaterThan(1);
+    });
+
+    it("surfaces feature acceptance for selected milestone without requiring slice expansion", async () => {
+      const missionDetail = createFn4613MissionDetail();
+      missionDetail.milestones[1].acceptanceCriteria = "";
+      globalThis.fetch = createDetailFetchMockForMissionDetail(missionDetail);
+
+      render(<MissionManager isOpen={true} isInline={true} onClose={vi.fn()} addToast={vi.fn()} />);
+      fireEvent.click(await screen.findByText("Build Auth System"));
+      await waitForDetailLoaded("Milestone One");
+
+      fireEvent.click(screen.getByText("Milestone Two"));
+      const rollup = await screen.findByTestId("milestone-feature-acceptance-rollup");
+      expect(within(rollup).getByText("Feature Two")).toBeInTheDocument();
+      expect(within(rollup).getByText("Feature two acceptance criteria", { exact: false })).toBeInTheDocument();
+    });
+
+    it("keeps milestone acceptance precedence over feature rollup", async () => {
+      const missionDetail = createFn4613MissionDetail();
+      globalThis.fetch = createDetailFetchMockForMissionDetail(missionDetail);
+
+      render(<MissionManager isOpen={true} onClose={vi.fn()} addToast={vi.fn()} />);
+      fireEvent.click(await screen.findByText("Build Auth System"));
+      await waitForDetailLoaded("Milestone One");
+
+      fireEvent.click(screen.getByText("Milestone Two"));
+      await waitFor(() => {
+        expect(screen.getByText("Milestone two acceptance criteria", { exact: false })).toBeInTheDocument();
+      });
+      expect(screen.queryByTestId("milestone-feature-acceptance-rollup")).not.toBeInTheDocument();
+    });
+  });
+
   describe("milestone assertions empty-state", () => {
     const emptyAssertionsCopy = "No assertions defined. Add one to define completion criteria.";