Fix exporter

app.py

@@ -240,11 +240,13 @@ async def health() -> Dict[str, str]:
 
 
 @app.get("/files/{session_id}/{kind}/{filename}")
-async def serve_generated_file(session_id: str, kind: str, filename: str):
+async def serve_generated_file(session_id: str, kind: str, filename: str, download: bool = False):
     path = _session_root(session_id) / kind / filename
     if not path.exists():
         return JSONResponse({"error": "file not found"}, status_code=404)
-    return FileResponse(path)
+    if download:
+        return FileResponse(path, filename=filename)
+    return FileResponse(path, content_disposition_type="inline")
 
 
 app.mount("/static", StaticFiles(directory=str(FRONTEND_DIR)), name="frontend-static")

frontend/app.js

@@ -251,7 +251,7 @@ const actionHandlers = {
       downloadCurrentExport();
       return;
     }
-    await requestExport();
+    await requestExport({ autoDownload: true });
   },
   goConfigure() {
     state.step = "configure";
@@ -427,7 +427,7 @@ function updateRenderState(payload) {
   }
 }
 
-async function requestExport() {
+async function requestExport(options = {}) {
   if (!state.client) return;
   state.errorMessage = "";
   state.statusMessage = `Preparing ${state.exportFormat.toUpperCase()} export…`;
@@ -447,7 +447,12 @@ async function requestExport() {
     state.exportFile = payload;
     state.exportPlayerTrackIndex = clampTrackIndex(state.exportPlayerTrackIndex, Math.max(1, includedChapters().length));
     state.previewUrl = payload.url || state.previewUrl;
-    state.statusMessage = `${state.exportFormat.toUpperCase()} export ready.`;
+    if (options.autoDownload && payload.url) {
+      downloadCurrentExport(payload);
+      state.statusMessage = `${state.exportFormat.toUpperCase()} export ready. Download starting…`;
+    } else {
+      state.statusMessage = `${state.exportFormat.toUpperCase()} export ready.`;
+    }
   } catch (error) {
     state.errorMessage = error.message;
   }
@@ -867,7 +872,7 @@ function renderExport() {
       </div>
       <div>
         <button class="btn-primary" data-action="exportBook">${state.exportFile ? "Download again" : "Download audiobook"}</button>
-        ${state.exportFile ? `<div style="margin-top:10px;"><a href="${state.exportFile.url}" target="_blank" rel="noopener" download="${escapeAttr(exportFilename())}">Open exported file</a></div>` : `<div style="margin-top:10px; color:var(--faint); font-size:12.5px;">with embedded chapter markers</div>`}
+        ${state.exportFile ? `<div style="margin-top:10px;"><a href="${escapeAttr(buildDownloadUrl(state.exportFile.url))}" target="_blank" rel="noopener" download="${escapeAttr(exportFilename())}">Download exported file</a></div>` : `<div style="margin-top:10px; color:var(--faint); font-size:12.5px;">with embedded chapter markers</div>`}
       </div>
     </div>
 
@@ -1330,14 +1335,20 @@ function exportFilename() {
   return `${base}.${state.exportFormat}`;
 }
 
-function downloadCurrentExport() {
-  if (!state.exportFile?.url) return;
-  const link = document.createElement("a");
-  link.href = state.exportFile.url;
-  link.download = exportFilename();
-  document.body.appendChild(link);
-  link.click();
-  link.remove();
+function buildDownloadUrl(url) {
+  const downloadUrl = new URL(url, window.location.origin);
+  downloadUrl.searchParams.set("download", "1");
+  return downloadUrl.toString();
+}
+
+function downloadCurrentExport(exportFile = state.exportFile) {
+  if (!exportFile?.url) return;
+  document.getElementById("download-frame")?.remove();
+  const frame = document.createElement("iframe");
+  frame.id = "download-frame";
+  frame.hidden = true;
+  frame.src = buildDownloadUrl(exportFile.url);
+  document.body.appendChild(frame);
 }
 
 function canStartRender() {

tests/test_frontend_export_controls.py

@@ -17,3 +17,10 @@ def test_export_screen_uses_downloadable_export_links() -> None:
 
     assert "downloadCurrentExport()" in source
     assert 'download="${escapeAttr(exportFilename())}"' in source
+
+
+def test_export_screen_prepares_attachment_downloads() -> None:
+    source = Path("frontend/app.js").read_text(encoding="utf-8")
+
+    assert "await requestExport({ autoDownload: true });" in source
+    assert 'searchParams.set("download", "1")' in source

tests/test_render_api.py

@@ -1,3 +1,4 @@
+import asyncio
 import importlib
 import sys
 from types import SimpleNamespace
@@ -5,6 +6,7 @@ from types import SimpleNamespace
 import pytest
 
 import gradio as gr
+from fastapi.responses import FileResponse
 
 
 def test_start_render_api_registers_one_streamed_output() -> None:
@@ -102,3 +104,28 @@ def test_generate_preview_api_exposes_model_and_backend(monkeypatch) -> None:
     assert payload["url"] == "/files/session-a/previews/c1.wav"
     assert payload["backend"] == "modal"
     assert payload["model"] == "magpie"
+
+
+def test_serve_generated_file_supports_attachment_downloads(tmp_path, monkeypatch) -> None:
+    sys.modules.pop("app", None)
+    module = importlib.import_module("app")
+
+    session_root = tmp_path / "session-a"
+    export_path = session_root / "exports" / "reading-room.m4a"
+    export_path.parent.mkdir(parents=True, exist_ok=True)
+    export_path.write_bytes(b"m4a")
+
+    monkeypatch.setattr(module, "_session_root", lambda _session_id: session_root)
+
+    response = asyncio.run(
+        module.serve_generated_file(
+            session_id="session-a",
+            kind="exports",
+            filename="reading-room.m4a",
+            download=True,
+        )
+    )
+
+    assert isinstance(response, FileResponse)
+    assert "attachment" in response.headers["content-disposition"]
+    assert "reading-room.m4a" in response.headers["content-disposition"]