Fix browser file operations and persist visible save times

Preserve JSON Content-Type when custom idempotency headers are supplied. Expose the latest accepted folder operation timestamp so browser saves remain visible before an agent runs and after all files are deleted.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

ui/src/api/client.test.ts

@@ -41,6 +41,27 @@ afterEach(() => {
   vi.unstubAllGlobals();
 });
 
+describe("request headers", () => {
+  it("keeps JSON content type when a mutation supplies an idempotency header", async () => {
+    fetchMock.mockResolvedValue(jsonResponse({ applied: true }));
+    await api.post("/work-folder/operations", { action: "delete", path: "note.md" },
+      { headers: { "Idempotency-Key": "delete-note" } });
+    const request = fetchMock.mock.calls[0]![1] as RequestInit;
+    const headers = new Headers(request.headers);
+    expect(headers.get("Content-Type")).toBe("application/json");
+    expect(headers.get("Idempotency-Key")).toBe("delete-note");
+    expect(JSON.parse(String(request.body))).toEqual({ action: "delete", path: "note.md" });
+  });
+  it("preserves a raw upload's explicit content type", async () => {
+    fetchMock.mockResolvedValue(jsonResponse({ applied: true }));
+    const body = new Blob(["file bytes"]);
+    await api.putRaw("/work-folder/content", body, { headers: { "Idempotency-Key": "upload" } });
+    const request = fetchMock.mock.calls[0]![1] as RequestInit;
+    expect(new Headers(request.headers).get("Content-Type")).toBe("application/octet-stream");
+    expect(request.body).toBe(body);
+  });
+});
+
 describe("tenant-session recovery", () => {
   it("keeps concurrent failures pending and schedules one top-level reload", async () => {
     const reload = vi.fn();

ui/src/api/client.ts

@@ -51,9 +51,9 @@ async function request<T>(path: string, init?: RequestInit): Promise<T> {
   applyObservabilityHeaders(headers);
 
   const res = await fetch(`${BASE}${path}`, {
-    headers,
     credentials: "include",
     ...init,
+    headers,
   });
   if (!res.ok) {
     const errorBody = await res.json().catch(() => null);

ui/src/api/work-folders.ts

@@ -8,14 +8,16 @@ export const workFoldersApi = {
   async list(owner: WorkFolderOwner, trash = false) {
     const files: WorkFile[] = [];
     let cursor: string | null = null;
+    let lastSavedAt: string | null = null;
     do {
       const query = new URLSearchParams({ trash: String(trash), limit: "1000", ...(cursor ? { cursor } : {}) });
       const page: WorkFolderListing = await api.get(`${base(owner)}?${query}`);
       files.push(...page.files);
+      if (page.lastSavedAt && (!lastSavedAt || page.lastSavedAt > lastSavedAt)) lastSavedAt = page.lastSavedAt;
       cursor = page.nextCursor;
     } while (cursor && files.length < 100_000);
     if (cursor) throw new Error("This folder is too large to display in one view");
-    return files;
+    return { files, lastSavedAt };
   },
   upload: (owner: WorkFolderOwner, file: File, filePath: string, operationId: string) =>
     api.putRaw(`${base(owner)}/content?${new URLSearchParams({ path: filePath })}`, file,