chore: skip all pauses in all DevTools universes (#631)

Author: szuend

src/DevtoolsUtils.ts

@@ -247,6 +247,8 @@ const DEFAULT_FACTORY: TargetUniverseFactoryFn = async (page: Page) => {
   const connection = new PuppeteerDevToolsConnection(session);
 
   const targetManager = universe.context.get(TargetManager);
+  targetManager.observeModels(DebuggerModel, SKIP_ALL_PAUSES);
+
   const target = targetManager.createTarget(
     'main',
     '',
@@ -258,3 +260,18 @@ const DEFAULT_FACTORY: TargetUniverseFactoryFn = async (page: Page) => {
   );
   return {target, universe};
 };
+
+// We don't want to pause any DevTools universe session ever on the MCP side.
+//
+// Note that calling `setSkipAllPauses` only affects the session on which it was
+// sent. This means DevTools can still pause, step and do whatever. We just won't
+// see the `Debugger.paused`/`Debugger.resumed` events on the MCP side.
+const SKIP_ALL_PAUSES = {
+  modelAdded(model: DebuggerModel): void {
+    void model.agent.invoke_setSkipAllPauses({skip: true});
+  },
+
+  modelRemoved(): void {
+    // Do nothing.
+  },
+};

tests/DevtoolsUtils.test.ts

@@ -9,7 +9,10 @@ import {afterEach, describe, it} from 'node:test';
 
 import sinon from 'sinon';
 
-import {AggregatedIssue} from '../node_modules/chrome-devtools-frontend/mcp/mcp.js';
+import {
+  AggregatedIssue,
+  DebuggerModel,
+} from '../node_modules/chrome-devtools-frontend/mcp/mcp.js';
 import {
   extractUrlLikeFromDevToolsTitle,
   urlsEqual,
@@ -240,4 +243,23 @@ describe('UniverseManager', () => {
       assert.notStrictEqual(manager.get(page), null);
     });
   });
+
+  it('ignores pauses', async () => {
+    await withBrowser(async (browser, page) => {
+      const manager = new UniverseManager(browser);
+      await manager.init([page]);
+      const targetUniverse = manager.get(page);
+      assert.ok(targetUniverse);
+      const model = targetUniverse.target.model(DebuggerModel);
+      assert.ok(model);
+
+      const pausedSpy = sinon.stub();
+      model.addEventListener('DebuggerPaused' as any, pausedSpy); // eslint-disable-line
+
+      const result = await page.evaluate('debugger; 1 + 1');
+      assert.strictEqual(result, 2);
+
+      sinon.assert.notCalled(pausedSpy);
+    });
+  });
 });