fix(browser): park webviews permanently paintable

Delete the renderer capture prep handshake and keep screenshots on the serialized invalidate/retry path. The capture harness now defaults to the production P1 attach-off parking check.

packages/desktop/src/features/browser-webviews/index.test.ts

@@ -0,0 +1,44 @@
+import { describe, expect, test } from "vitest";
+import { getPaseoBrowserIdForWebContents, registerPaseoBrowserWebContents } from "./index.js";
+
+class FakeRegisteredWebContents {
+  public readonly backgroundThrottlingCalls: boolean[] = [];
+  private destroyedListener: (() => void) | null = null;
+  private destroyed = false;
+
+  public constructor(public readonly id: number) {}
+
+  public isDestroyed(): boolean {
+    return this.destroyed;
+  }
+
+  public setBackgroundThrottling(allowed: boolean): void {
+    this.backgroundThrottlingCalls.push(allowed);
+  }
+
+  public once(event: "destroyed", listener: () => void): void {
+    expect(event).toBe("destroyed");
+    this.destroyedListener = listener;
+  }
+
+  public destroy(): void {
+    this.destroyed = true;
+    this.destroyedListener?.();
+  }
+}
+
+describe("registerPaseoBrowserWebContents", () => {
+  test("disables guest background throttling once when the webview is registered", () => {
+    const contents = new FakeRegisteredWebContents(9001);
+
+    registerPaseoBrowserWebContents(contents, "browser-throttle");
+
+    expect(contents.backgroundThrottlingCalls).toEqual([false]);
+    expect(getPaseoBrowserIdForWebContents(contents)).toBe("browser-throttle");
+
+    contents.destroy();
+
+    expect(getPaseoBrowserIdForWebContents(contents)).toBeNull();
+    expect(contents.backgroundThrottlingCalls).toEqual([false]);
+  });
+});

packages/desktop/src/features/browser-webviews/index.ts

@@ -11,6 +11,16 @@ export type { BrowserWorkspaceRegistration };
 
 const browserRegistry = new PaseoBrowserWebviewRegistry();
 
+interface BrowserWebContentsIdentity {
+  readonly id: number;
+  isDestroyed(): boolean;
+}
+
+interface RegisteredBrowserWebContents extends BrowserWebContentsIdentity {
+  setBackgroundThrottling(allowed: boolean): void;
+  once(event: "destroyed", listener: () => void): void;
+}
+
 function getBrowserIdFromWebviewPartition(partition: string | undefined): string | null {
   const prefix = "persist:paseo-browser-";
   if (!partition?.startsWith(prefix)) {
@@ -36,14 +46,20 @@ export function listRegisteredPaseoBrowserIds(): string[] {
     .filter((browserId) => getPaseoBrowserWebContents(browserId));
 }
 
-export function registerPaseoBrowserWebContents(contents: WebContents, browserId: string): void {
+export function registerPaseoBrowserWebContents(
+  contents: RegisteredBrowserWebContents,
+  browserId: string,
+): void {
+  contents.setBackgroundThrottling(false);
   browserRegistry.registerWebContents({ webContentsId: contents.id, browserId });
   contents.once("destroyed", () => {
     browserRegistry.unregisterWebContents(contents.id);
   });
 }
 
-export function getPaseoBrowserIdForWebContents(contents: WebContents | null): string | null {
+export function getPaseoBrowserIdForWebContents(
+  contents: BrowserWebContentsIdentity | null,
+): string | null {
   if (!contents || contents.isDestroyed()) {
     return null;
   }