fix: handle extension relay session reuse

CHANGELOG.md

@@ -48,6 +48,7 @@ Docs: https://docs.clawd.bot
 - Agents: treat plugin-only tool allowlists as opt-ins; keep core tools enabled. (#1467)
 - Exec approvals: persist allowlist entry ids to keep macOS allowlist rows stable. (#1521) Thanks @ngutman.
 - MS Teams (plugin): remove `.default` suffix from Graph scopes to avoid double-appending. (#1507) Thanks @Evizero.
+- Browser: keep extension relay tabs controllable when the extension reuses a session id after switching tabs. (#1160)
 
 ## 2026.1.22
 

src/browser/extension-relay.test.ts

@@ -247,4 +247,71 @@ describe("chrome extension relay server", () => {
     cdp.close();
     ext.close();
   }, 15_000);
+
+  it("rebroadcasts attach when a session id is reused for a new target", async () => {
+    const port = await getFreePort();
+    cdpUrl = `http://127.0.0.1:${port}`;
+    await ensureChromeExtensionRelayServer({ cdpUrl });
+
+    const ext = new WebSocket(`ws://127.0.0.1:${port}/extension`);
+    await waitForOpen(ext);
+
+    const cdp = new WebSocket(`ws://127.0.0.1:${port}/cdp`);
+    await waitForOpen(cdp);
+    const q = createMessageQueue(cdp);
+
+    ext.send(
+      JSON.stringify({
+        method: "forwardCDPEvent",
+        params: {
+          method: "Target.attachedToTarget",
+          params: {
+            sessionId: "shared-session",
+            targetInfo: {
+              targetId: "t1",
+              type: "page",
+              title: "First",
+              url: "https://example.com",
+            },
+            waitingForDebugger: false,
+          },
+        },
+      }),
+    );
+
+    const first = JSON.parse(await q.next()) as { method?: string; params?: unknown };
+    expect(first.method).toBe("Target.attachedToTarget");
+    expect(JSON.stringify(first.params ?? {})).toContain("t1");
+
+    ext.send(
+      JSON.stringify({
+        method: "forwardCDPEvent",
+        params: {
+          method: "Target.attachedToTarget",
+          params: {
+            sessionId: "shared-session",
+            targetInfo: {
+              targetId: "t2",
+              type: "page",
+              title: "Second",
+              url: "https://example.org",
+            },
+            waitingForDebugger: false,
+          },
+        },
+      }),
+    );
+
+    const received: Array<{ method?: string; params?: unknown }> = [];
+    received.push(JSON.parse(await q.next()) as never);
+    received.push(JSON.parse(await q.next()) as never);
+
+    const detached = received.find((m) => m.method === "Target.detachedFromTarget");
+    const attached = received.find((m) => m.method === "Target.attachedToTarget");
+    expect(JSON.stringify(detached?.params ?? {})).toContain("t1");
+    expect(JSON.stringify(attached?.params ?? {})).toContain("t2");
+
+    cdp.close();
+    ext.close();
+  });
 });

src/browser/extension-relay.ts

@@ -477,13 +477,23 @@ export async function ensureChromeExtensionRelayServer(opts: {
           const targetType = attached?.targetInfo?.type ?? "page";
           if (targetType !== "page") return;
           if (attached?.sessionId && attached?.targetInfo?.targetId) {
-            const already = connectedTargets.has(attached.sessionId);
+            const prev = connectedTargets.get(attached.sessionId);
+            const nextTargetId = attached.targetInfo.targetId;
+            const prevTargetId = prev?.targetId;
+            const changedTarget = Boolean(prev && prevTargetId && prevTargetId !== nextTargetId);
             connectedTargets.set(attached.sessionId, {
               sessionId: attached.sessionId,
-              targetId: attached.targetInfo.targetId,
+              targetId: nextTargetId,
               targetInfo: attached.targetInfo,
             });
-            if (!already) {
+            if (changedTarget && prevTargetId) {
+              broadcastToCdpClients({
+                method: "Target.detachedFromTarget",
+                params: { sessionId: attached.sessionId, targetId: prevTargetId },
+                sessionId: attached.sessionId,
+              });
+            }
+            if (!prev || changedTarget) {
               broadcastToCdpClients({ method, params, sessionId });
             }
             return;