From 682ddb1e74e501fe82ecbe689b685325203cf2ea Mon Sep 17 00:00:00 2001
From: Ted Li <tl2493@columbia.edu>
Date: Sun, 24 May 2026 13:23:18 -0700
Subject: [PATCH] fix(daemon): activate tabs before mouse input

---
 .../src/__tests__/command-dispatch.test.ts    | 131 ++++++++++++++++++
 packages/daemon/src/command-dispatch.ts       |   8 ++
 2 files changed, 139 insertions(+)
 create mode 100644 packages/daemon/src/__tests__/command-dispatch.test.ts

diff --git a/packages/daemon/src/__tests__/command-dispatch.test.ts b/packages/daemon/src/__tests__/command-dispatch.test.ts
new file mode 100644
index 0000000..bf2601f
--- /dev/null
+++ b/packages/daemon/src/__tests__/command-dispatch.test.ts
@@ -0,0 +1,131 @@
+import { describe, it } from "node:test";
+import assert from "node:assert/strict";
+import type { Request } from "@bb-browser/shared";
+import { dispatchRequest } from "../command-dispatch.js";
+import type { CdpConnection, CdpTargetInfo } from "../cdp-connection.js";
+import { TabStateManager } from "../tab-state.js";
+
+type RecordedCommand = {
+  scope: "browser" | "session";
+  targetId?: string;
+  method: string;
+  params: Record<string, unknown>;
+};
+
+class FakeCdp {
+  readonly tabManager = new TabStateManager();
+  readonly target: CdpTargetInfo = {
+    id: "target-background",
+    type: "page",
+    title: "Example",
+    url: "https://example.com",
+  };
+  readonly commands: RecordedCommand[] = [];
+  currentTargetId: string | undefined;
+
+  constructor() {
+    const tab = this.tabManager.addTab(this.target.id);
+    tab.refs["1"] = {
+      backendDOMNodeId: 42,
+      role: "button",
+      name: "Submit",
+      tagName: "button",
+    };
+  }
+
+  async ensurePageTarget(): Promise<CdpTargetInfo> {
+    this.currentTargetId = this.target.id;
+    return this.target;
+  }
+
+  async browserCommand<T = unknown>(method: string, params: Record<string, unknown> = {}): Promise<T> {
+    this.commands.push({ scope: "browser", method, params });
+    return {} as T;
+  }
+
+  async sessionCommand<T = unknown>(
+    targetId: string,
+    method: string,
+    params: Record<string, unknown> = {},
+  ): Promise<T> {
+    this.commands.push({ scope: "session", targetId, method, params });
+
+    if (method === "DOM.resolveNode") {
+      return { object: { objectId: "object-1" } } as T;
+    }
+    if (method === "Runtime.callFunctionOn") {
+      return { result: { value: { x: 100, y: 200 } } } as T;
+    }
+    return {} as T;
+  }
+}
+
+function fakeConnection(): CdpConnection {
+  return new FakeCdp() as unknown as CdpConnection;
+}
+
+describe("dispatchRequest input activation", () => {
+  it("activates a background target before resolving click coordinates", async () => {
+    const cdp = fakeConnection();
+
+    const response = await dispatchRequest(cdp, {
+      id: "click-1",
+      method: "click",
+      ref: "1",
+    } satisfies Request);
+
+    assert.equal(response.error, undefined);
+    assert.equal(response.result?.tab, "ound");
+    assert.equal(typeof response.result?.seq, "number");
+
+    const commands = (cdp as unknown as FakeCdp).commands;
+    const activateIndex = commands.findIndex(
+      (cmd) => cmd.scope === "browser" && cmd.method === "Target.activateTarget",
+    );
+    const resolveIndex = commands.findIndex((cmd) => cmd.method === "DOM.resolveNode");
+    const pressIndex = commands.findIndex(
+      (cmd) => cmd.method === "Input.dispatchMouseEvent" && cmd.params.type === "mousePressed",
+    );
+
+    assert.notEqual(activateIndex, -1);
+    assert.notEqual(resolveIndex, -1);
+    assert.notEqual(pressIndex, -1);
+    assert.ok(activateIndex < resolveIndex);
+    assert.ok(activateIndex < pressIndex);
+    assert.deepEqual(commands[activateIndex].params, { targetId: "target-background" });
+  });
+
+  it("activates a background target before dispatching wheel events", async () => {
+    const cdp = fakeConnection();
+
+    const response = await dispatchRequest(cdp, {
+      id: "scroll-1",
+      method: "scroll",
+      direction: "down",
+      pixels: 200,
+    } satisfies Request);
+
+    assert.equal(response.error, undefined);
+    assert.equal(response.result?.tab, "ound");
+    assert.equal(typeof response.result?.seq, "number");
+
+    const commands = (cdp as unknown as FakeCdp).commands;
+    const activateIndex = commands.findIndex(
+      (cmd) => cmd.scope === "browser" && cmd.method === "Target.activateTarget",
+    );
+    const wheelIndex = commands.findIndex(
+      (cmd) => cmd.method === "Input.dispatchMouseEvent" && cmd.params.type === "mouseWheel",
+    );
+
+    assert.notEqual(activateIndex, -1);
+    assert.notEqual(wheelIndex, -1);
+    assert.ok(activateIndex < wheelIndex);
+    assert.deepEqual(commands[wheelIndex].params, {
+      type: "mouseWheel",
+      x: 0,
+      y: 0,
+      deltaX: 0,
+      deltaY: 200,
+    });
+  });
+});
diff --git a/packages/daemon/src/command-dispatch.ts b/packages/daemon/src/command-dispatch.ts
index 2b5751a..96c78fe 100644
--- a/packages/daemon/src/command-dispatch.ts
+++ b/packages/daemon/src/command-dispatch.ts
@@ -400,6 +400,10 @@ async function mouseClick(cdp: CdpConnection, targetId: string, x: number, y: nu
   });
 }
 
+async function activateTarget(cdp: CdpConnection, targetId: string): Promise<void> {
+  await cdp.browserCommand("Target.activateTarget", { targetId });
+}
+
 async function insertTextIntoNode(
   cdp: CdpConnection,
   targetId: string,
@@ -763,6 +767,9 @@ export async function dispatchRequest(
         role: refInfo?.role,
         tag: refInfo?.tagName,
       });
+      if (request.method === "click") {
+        await activateTarget(cdp, target.id);
+      }
       const backendNodeId = await parseRef(cdp, target.id, tab, request.ref);
       const point = await getInteractablePoint(cdp, target.id, backendNodeId);
       await cdp.sessionCommand(target.id, "Input.dispatchMouseEvent", {
@@ -886,6 +893,7 @@ export async function dispatchRequest(
         case "left": deltaX = -pixels; break;
         case "right": deltaX = pixels; break;
       }
+      await activateTarget(cdp, target.id);
       await cdp.sessionCommand(target.id, "Input.dispatchMouseEvent", {
         type: "mouseWheel", x: 0, y: 0, deltaX, deltaY,
       });