From c52745bfbfd1499b6fb07ae6ac3c709ebad56117 Mon Sep 17 00:00:00 2001
From: Niklas Kietaibl <niklas@makeautomation.at>
Date: Thu, 18 Jun 2026 13:07:18 +0700
Subject: [PATCH 1/2] fix(desktop): restore correct filename in save dialog for
 attachment downloads
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Without a will-download handler, Electron derives the suggested filename
from the URL path (/api/attachments/<id>/download → download.txt) and
ignores the Content-Disposition header sent by the server.

Adding the handler and forwarding item.getFilename() — which reads the
Content-Disposition filename — restores the correct name and extension
in the native save dialog.

Fixes #4153
---
 apps/desktop/src/main/index.ts | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/apps/desktop/src/main/index.ts b/apps/desktop/src/main/index.ts
index 03f25cf39b..ac4bcf4690 100644
--- a/apps/desktop/src/main/index.ts
+++ b/apps/desktop/src/main/index.ts
@@ -219,6 +219,16 @@ function createWindow(): void {
     window.webContents.send("locale:system-changed", current);
   });
 
+  // Without this handler, Electron derives the save-dialog filename from the
+  // URL path (e.g. "/api/attachments/<id>/download" → "download.txt") and
+  // ignores the Content-Disposition header sent by the server. Forwarding
+  // getFilename() restores the correct name from Content-Disposition.
+  window.webContents.session.on("will-download", (_event, item) => {
+    item.setSaveDialogOptions({
+      defaultPath: join(app.getPath("downloads"), item.getFilename()),
+    });
+  });
+
   window.webContents.setWindowOpenHandler((details) => {
     openExternalSafely(details.url);
     return { action: "deny" };

From 2a3a849f9ef9891a8644d6a3b99d1b41c90114e0 Mon Sep 17 00:00:00 2001
From: Niklas Kietaibl <niklas@makeautomation.at>
Date: Thu, 18 Jun 2026 14:57:29 +0700
Subject: [PATCH 2/2] refactor: guard will-download handler against duplicate
 session registration

On macOS, app activate can call createWindow() again after all windows
are closed. window.webContents.session is shared, so registering the
will-download handler inside createWindow() would add duplicate listeners.

Extract into installDownloadSaveDialogHandler() with a WeakSet guard so
the handler is registered at most once per session.
---
 apps/desktop/src/main/index.ts | 26 +++++++++++++++++---------
 1 file changed, 17 insertions(+), 9 deletions(-)

diff --git a/apps/desktop/src/main/index.ts b/apps/desktop/src/main/index.ts
index ac4bcf4690..5b6192fa08 100644
--- a/apps/desktop/src/main/index.ts
+++ b/apps/desktop/src/main/index.ts
@@ -29,6 +29,22 @@ import {
   clearFreezeBreadcrumb,
 } from "./freeze-breadcrumb";
 
+// Guards against registering the will-download handler more than once on the
+// same session. window.webContents.session is shared, and createWindow() can
+// be called again on macOS (app "activate" after all windows are closed).
+const downloadDialogSessions = new WeakSet<Electron.Session>();
+
+function installDownloadSaveDialogHandler(window: BrowserWindow): void {
+  const { session } = window.webContents;
+  if (downloadDialogSessions.has(session)) return;
+  downloadDialogSessions.add(session);
+  session.on("will-download", (_event, item) => {
+    item.setSaveDialogOptions({
+      defaultPath: join(app.getPath("downloads"), item.getFilename()),
+    });
+  });
+}
+
 // Bundled icon used for dock/taskbar branding. macOS/Windows production
 // builds let the OS pick up the icon from the .app bundle / .exe resources,
 // but Linux production needs an explicit BrowserWindow `icon` — AppImage
@@ -219,15 +235,7 @@ function createWindow(): void {
     window.webContents.send("locale:system-changed", current);
   });
 
-  // Without this handler, Electron derives the save-dialog filename from the
-  // URL path (e.g. "/api/attachments/<id>/download" → "download.txt") and
-  // ignores the Content-Disposition header sent by the server. Forwarding
-  // getFilename() restores the correct name from Content-Disposition.
-  window.webContents.session.on("will-download", (_event, item) => {
-    item.setSaveDialogOptions({
-      defaultPath: join(app.getPath("downloads"), item.getFilename()),
-    });
-  });
+  installDownloadSaveDialogHandler(window);
 
   window.webContents.setWindowOpenHandler((details) => {
     openExternalSafely(details.url);