fix(ui): return to current document revision preview

ui/src/components/IssueDocumentsSection.test.tsx

@@ -119,6 +119,35 @@ vi.mock("@/components/ui/dropdown-menu", async () => {
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
 (globalThis as any).IS_REACT_ACT_ENVIRONMENT = true;
 
+const localStorageEntries = new Map<string, string>();
+
+function ensureLocalStorageMock() {
+  if (
+    typeof window.localStorage?.getItem === "function"
+    && typeof window.localStorage?.setItem === "function"
+    && typeof window.localStorage?.removeItem === "function"
+    && typeof window.localStorage?.clear === "function"
+  ) {
+    return;
+  }
+
+  Object.defineProperty(window, "localStorage", {
+    configurable: true,
+    value: {
+      getItem: (key: string) => localStorageEntries.get(key) ?? null,
+      setItem: (key: string, value: string) => {
+        localStorageEntries.set(key, value);
+      },
+      removeItem: (key: string) => {
+        localStorageEntries.delete(key);
+      },
+      clear: () => {
+        localStorageEntries.clear();
+      },
+    },
+  });
+}
+
 function deferred<T>() {
   let resolve!: (value: T) => void;
   const promise = new Promise<T>((res) => {
@@ -221,6 +250,7 @@ describe("IssueDocumentsSection", () => {
   beforeEach(() => {
     container = document.createElement("div");
     document.body.appendChild(container);
+    ensureLocalStorageMock();
     window.localStorage.clear();
     vi.clearAllMocks();
     markdownEditorMockState.emitMountEmptyChange = false;
@@ -311,6 +341,79 @@ describe("IssueDocumentsSection", () => {
     queryClient.clear();
   });
 
+  it("returns from a historical preview when the current revision only exists in derived state", async () => {
+    const currentDocument = createIssueDocument({
+      body: "Current plan body",
+      latestRevisionId: "revision-4",
+      latestRevisionNumber: 4,
+      updatedAt: new Date("2026-03-31T12:05:00.000Z"),
+    });
+    const issue = createIssue();
+    const root = createRoot(container);
+    const queryClient = new QueryClient({
+      defaultOptions: {
+        queries: {
+          retry: false,
+        },
+        mutations: {
+          retry: false,
+        },
+      },
+    });
+
+    mockIssuesApi.listDocuments.mockResolvedValue([currentDocument]);
+    queryClient.setQueryData(
+      queryKeys.issues.documentRevisions(issue.id, "plan"),
+      [
+        createRevision({
+          id: "revision-3",
+          revisionNumber: 3,
+          body: "Historical plan body",
+          createdAt: new Date("2026-03-31T11:00:00.000Z"),
+        }),
+      ],
+    );
+
+    await act(async () => {
+      root.render(
+        <QueryClientProvider client={queryClient}>
+          <IssueDocumentsSection issue={issue} canDeleteDocuments={false} />
+        </QueryClientProvider>,
+      );
+    });
+    await flush();
+    await flush();
+
+    expect(container.textContent).toContain("Current plan body");
+
+    const revisionButtons = Array.from(container.querySelectorAll("button"));
+    const historicalRevisionButton = revisionButtons.find((button) => button.textContent?.includes("rev 3"));
+    expect(historicalRevisionButton).toBeTruthy();
+
+    await act(async () => {
+      historicalRevisionButton?.dispatchEvent(new MouseEvent("click", { bubbles: true }));
+    });
+
+    expect(container.textContent).toContain("Viewing revision 3");
+    expect(container.textContent).toContain("Historical plan body");
+
+    const currentRevisionButton = Array.from(container.querySelectorAll("button"))
+      .find((button) => button.textContent?.includes("rev 4"));
+    expect(currentRevisionButton).toBeTruthy();
+
+    await act(async () => {
+      currentRevisionButton?.dispatchEvent(new MouseEvent("click", { bubbles: true }));
+    });
+
+    expect(container.textContent).not.toContain("Viewing revision 3");
+    expect(container.textContent).toContain("Current plan body");
+
+    await act(async () => {
+      root.unmount();
+    });
+    queryClient.clear();
+  });
+
   it("ignores mount-time editor change noise before a document is actively being edited", async () => {
     markdownEditorMockState.emitMountEmptyChange = true;
 

ui/src/components/IssueDocumentsSection.tsx

@@ -537,13 +537,13 @@ export function IssueDocumentsSection({
   }, []);
 
   const previewRevision = useCallback((doc: IssueDocument, revisionId: string) => {
-    const revisions = getDocumentRevisions(doc.key);
-    const selectedRevision = revisions.find((revision) => revision.id === revisionId);
-    if (!selectedRevision) return;
-    if (selectedRevision.id === doc.latestRevisionId) {
+    if (revisionId === doc.latestRevisionId) {
       returnToLatestRevision(doc.key);
       return;
     }
+    const revisions = getDocumentRevisions(doc.key);
+    const selectedRevision = revisions.find((revision) => revision.id === revisionId);
+    if (!selectedRevision) return;
     if (documentConflict?.key === doc.key || documentHasUnsavedChanges(doc, draft)) {
       setError("Save or cancel your local changes before viewing an older revision.");
       return;