fix(desktop): keep preview download settings out of app exports

apps/desktop/src/preview/CdpRelay.test.ts

@@ -178,7 +178,7 @@ describe("CDP relay extra sessions", () => {
 });
 
 describe("CDP relay downloads", () => {
-  it("applies the server's download directory and reports downloads on the root session", async () => {
+  it("captures preview downloads without changing the default browser context", async () => {
     const send = vi.fn(async () => ({}));
     const directories: Array<string | null> = [];
     const written: Array<Record<string, unknown>> = [];
@@ -201,15 +201,99 @@ describe("CDP relay downloads", () => {
     );
     await settle();
     expect(directories).toEqual(["/srv/artifacts"]);
-    expect(send).toHaveBeenCalledWith(
-      "Browser.setDownloadBehavior",
-      { behavior: "allowAndName", downloadPath: "/srv/artifacts", eventsEnabled: true },
-      undefined,
-    );
+    expect(send.mock.calls).toEqual([
+      ["Page.setDownloadBehavior", { behavior: "default" }, undefined],
+    ]);
     written.length = 0;
-    relay.event("Browser.downloadWillBegin", { guid: "g1", suggestedFilename: "r.csv" }, "");
+    relay.event("Page.downloadWillBegin", { guid: "g1", suggestedFilename: "r.csv" }, "");
+    relay.event("Page.downloadProgress", { guid: "g1", state: "completed" }, "");
     expect(written).toEqual([
       { method: "Browser.downloadWillBegin", params: { guid: "g1", suggestedFilename: "r.csv" } },
+      { method: "Browser.downloadProgress", params: { guid: "g1", state: "completed" } },
     ]);
   });
+
+  it("keeps denial scoped to the preview and restores Electron's save handling when allowed", async () => {
+    const send = vi.fn(async () => ({}));
+    const directories: Array<string | null> = [];
+    const relay = createCdpRelayConnection(
+      makeTarget(send, (directory) => directories.push(directory)),
+      () => {},
+    );
+    for (const [id, behavior] of ["deny", "allowAndName"].entries()) {
+      relay.receive(
+        JSON.stringify({
+          id,
+          method: "Browser.setDownloadBehavior",
+          params: { behavior, downloadPath: "/srv/artifacts" },
+        }),
+      );
+      await settle();
+    }
+    expect(directories).toEqual([null, "/srv/artifacts"]);
+    expect(send.mock.calls).toEqual([
+      ["Page.setDownloadBehavior", { behavior: "deny" }, undefined],
+      ["Page.setDownloadBehavior", { behavior: "default" }, undefined],
+    ]);
+  });
+
+  it("does not publish download events when the connection has disabled them", async () => {
+    const written: Array<Record<string, unknown>> = [];
+    const relay = createCdpRelayConnection(makeTarget(vi.fn(async () => ({}))), (raw) =>
+      written.push(JSON.parse(raw)),
+    );
+    relay.receive(JSON.stringify({ id: 1, method: "Target.setAutoAttach", params: {} }));
+    relay.receive(
+      JSON.stringify({
+        id: 2,
+        method: "Browser.setDownloadBehavior",
+        params: { behavior: "allowAndName", downloadPath: "/srv/artifacts", eventsEnabled: false },
+      }),
+    );
+    await settle();
+    written.length = 0;
+    relay.event("Page.downloadWillBegin", { guid: "g1" }, "");
+    relay.event("Page.downloadProgress", { guid: "g1", state: "completed" }, "");
+    expect(written).toEqual([]);
+  });
+
+  it.each([false, true])(
+    "keeps the previous download event setting (%s) when configuration fails",
+    async (enabled) => {
+      const send = vi
+        .fn(async () => ({}))
+        .mockResolvedValueOnce({})
+        .mockRejectedValueOnce(new Error("Page command rejected"));
+      const written: Array<Record<string, unknown>> = [];
+      const relay = createCdpRelayConnection(makeTarget(send), (raw) =>
+        written.push(JSON.parse(raw)),
+      );
+      relay.receive(JSON.stringify({ id: 1, method: "Target.setAutoAttach", params: {} }));
+      for (const [id, eventsEnabled] of [enabled, !enabled].entries()) {
+        relay.receive(
+          JSON.stringify({
+            id: id + 2,
+            method: "Browser.setDownloadBehavior",
+            params: { behavior: "allowAndName", downloadPath: "/srv/artifacts", eventsEnabled },
+          }),
+        );
+        await settle();
+      }
+      expect(written).toContainEqual({
+        id: 3,
+        error: { code: -32000, message: "Page command rejected" },
+      });
+      written.length = 0;
+      relay.event("Page.downloadWillBegin", { guid: "g1" }, "");
+      relay.event("Page.downloadProgress", { guid: "g1", state: "completed" }, "");
+      expect(written).toEqual(
+        enabled
+          ? [
+              { method: "Browser.downloadWillBegin", params: { guid: "g1" } },
+              { method: "Browser.downloadProgress", params: { guid: "g1", state: "completed" } },
+            ]
+          : [],
+      );
+    },
+  );
 });

apps/desktop/src/preview/CdpRelay.ts

@@ -53,6 +53,7 @@ export function createCdpRelayConnection(
 ): CdpRelayConnection {
   const send = (message: Record<string, unknown>) => write(JSON.stringify(message));
   let attached = false;
+  let downloadEventsEnabled = false;
   /** Relay-created page sessions share one real debugger; child frame sessions retain their own ids. */
   const sessions = new Map<string, "browser" | "page">([[PAGE_SESSION_ID, "page"]]);
   let sessionSequence = 0;
@@ -78,8 +79,14 @@ export function createCdpRelayConnection(
         const directory = command.params?.["downloadPath"];
         const allowed = command.params?.["behavior"] !== "deny" && typeof directory === "string";
         target.setDownloadDirectory(allowed ? directory : null);
-        const { browserContextId: _ignored, ...params } = command.params ?? {};
-        return target.send("Browser.setDownloadBehavior", params, undefined);
+        // Browser-scoped behavior targets Electron's app session; preview paths belong to will-download.
+        const result = await target.send(
+          "Page.setDownloadBehavior",
+          { behavior: command.params?.["behavior"] === "deny" ? "deny" : "default" },
+          undefined,
+        );
+        downloadEventsEnabled = command.params?.["eventsEnabled"] === true;
+        return result;
       }
       case "Browser.getVersion":
         return {
@@ -186,9 +193,10 @@ export function createCdpRelayConnection(
     },
     event: (method, params, sessionId) => {
       if (!attached) return;
+      if (method.startsWith("Page.download")) method = method.replace("Page.", "Browser.");
       // Download events are the browser's; Playwright listens on its root session.
       if (method.startsWith("Browser.download")) {
-        send({ method, params });
+        if (downloadEventsEnabled) send({ method, params });
         return;
       }
       // Electron reports the page's own events with an empty session id.

apps/desktop/src/preview/DesktopBrowserHost.test.ts

@@ -934,9 +934,11 @@ describe("DesktopBrowserHost", () => {
           }),
         }),
       );
-      debuggee.emit("Browser.downloadWillBegin", { guid: "guid-1", suggestedFilename: "r.csv" });
+      debuggee.emit("Page.downloadWillBegin", { guid: "guid-1", suggestedFilename: "r.csv" });
+      expect(host.placeDownload(makeDebuggee().tab.webContents, item)).toBe(false);
       expect(host.placeDownload(debuggee.tab.webContents, item)).toBe(true);
       expect(paths).toEqual(["/srv/downloads/guid-1"]);
+      expect(host.placeDownload(debuggee.tab.webContents, item)).toBe(false);
     }),
   );
 

apps/desktop/src/preview/DesktopBrowserHost.ts

@@ -422,7 +422,7 @@ export const make = Effect.gen(function* () {
       focusReleasing: false,
       screencasts: new Set(),
       onMessage: (_event, method, params, sessionId) => {
-        if (method === "Browser.downloadWillBegin") {
+        if (method === "Page.downloadWillBegin") {
           const guid = (params as { guid?: unknown } | undefined)?.guid;
           tab.pendingDownloadGuid = typeof guid === "string" ? guid : null;
         }