fix(frontend): retain presented artifacts in header dropdown (#3854)

* fix(frontend): retain presented artifacts in dropdown

* refactor(agents): trim file editing prompt context

* Revert "refactor(agents): trim file editing prompt context"

This reverts commit cad105265024335222e374692dde37424d11024b.

frontend/src/components/workspace/artifacts/artifact-file-detail.tsx

@@ -84,13 +84,41 @@ export function ArtifactFileDetail({
     }
     return filepathFromProps;
   }, [filepathFromProps, isWriteFile]);
-  const artifactOptions = useMemo(() => {
-    const list = artifacts ?? [];
-    if (list.includes(filepath)) {
-      return list;
+  // Keep these local because ChatBox replaces context artifacts with thread state.
+  const [openedPresentedFilepaths, setOpenedPresentedFilepaths] = useState<
+    string[]
+  >(() => {
+    if (isWriteFile || artifacts.includes(filepath)) {
+      return [];
     }
-    return [filepath, ...list];
-  }, [artifacts, filepath]);
+    return [filepath];
+  });
+  useEffect(() => {
+    if (isWriteFile || artifacts.includes(filepath)) {
+      return;
+    }
+    setOpenedPresentedFilepaths((current) => {
+      if (current.includes(filepath)) {
+        return current;
+      }
+      return [...current, filepath];
+    });
+  }, [artifacts, filepath, isWriteFile]);
+  const artifactOptions = useMemo(() => {
+    if (isWriteFile) {
+      return artifacts;
+    }
+    const currentIsPresented = !artifacts.includes(filepath);
+    const presentedFilepaths =
+      currentIsPresented && !openedPresentedFilepaths.includes(filepath)
+        ? [...openedPresentedFilepaths, filepath]
+        : openedPresentedFilepaths;
+    const presentedSet = new Set(presentedFilepaths);
+    return [
+      ...presentedFilepaths,
+      ...artifacts.filter((artifact) => !presentedSet.has(artifact)),
+    ];
+  }, [artifacts, filepath, isWriteFile, openedPresentedFilepaths]);
   const isSkillFile = useMemo(() => {
     return filepath.endsWith(".skill");
   }, [filepath]);

frontend/tests/e2e/artifact-preview.spec.ts

@@ -262,16 +262,16 @@ test.describe("Artifact preview stability", () => {
     ).toBeVisible();
   });
 
-  test("shows the title for a presented artifact missing from thread artifacts", async ({
+  test("keeps an opened presented artifact in the header dropdown", async ({
     page,
   }) => {
     mockLangGraphAPI(page, {
       threads: [
         {
           thread_id: PRESENTED_THREAD_ID,
-          title: "Presented artifact title fallback",
+          title: "Presented artifact dropdown history",
           messages: presentFilesMessages(),
-          artifacts: [],
+          artifacts: [MARKDOWN_ARTIFACT_PATH],
         },
       ],
     });
@@ -284,6 +284,15 @@ test.describe("Artifact preview stability", () => {
           body: "# Presented Report\n\nGenerated content",
         }),
     );
+    await page.route(
+      `**/api/threads/${PRESENTED_THREAD_ID}/artifacts/artifact-fixtures/report.md`,
+      (route) =>
+        route.fulfill({
+          status: 200,
+          contentType: "text/markdown",
+          body: "# Thread Report\n\nTracked artifact content",
+        }),
+    );
 
     await page.goto(`/workspace/chats/${PRESENTED_THREAD_ID}`);
 
@@ -295,11 +304,20 @@ test.describe("Artifact preview stability", () => {
 
     const artifactsPanel = page.locator("#artifacts");
 
-    // 1. Header title should fall back to the current filepath even though
-    //    thread.values.artifacts is empty.
     await expect(artifactsPanel.getByText("presented-report.md")).toBeVisible();
+    await expect(artifactsPanel.getByText("Presented Report")).toBeVisible();
 
-    // 2. Preview content should still render correctly.
+    const artifactSelect = artifactsPanel.getByRole("combobox");
+    await artifactSelect.click();
+    await page.getByRole("option", { name: "report.md", exact: true }).click();
+    await expect(artifactsPanel.getByText("Thread Report")).toBeVisible();
+
+    await artifactSelect.click();
+    const presentedOption = page.getByRole("option", {
+      name: "presented-report.md",
+    });
+    await expect(presentedOption).toBeVisible();
+    await presentedOption.click();
     await expect(artifactsPanel.getByText("Presented Report")).toBeVisible();
   });
 });