fix(record): record switch_tab and keep Trace v3 states per tab

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: shnpd

apps/extension/src/lib/__tests__/record-observation.test.ts

@@ -130,7 +130,7 @@ describe("applyTargetMatching while the previous action is still settling", () =
       url: URL,
       vomText: '@vom 1\n@e1 textbox "Search"',
     };
-    obs.settles.set(0, { draftIndex: 0, cancelled: false });
+    obs.settles.set(0, { draftIndex: 0, tabId: 4, cancelled: false });
     const draft: DraftTraceStep = {
       op: "click",
       target: { unmatched: true },

apps/extension/src/lib/__tests__/trace-reducer-v2.test.ts

@@ -41,6 +41,23 @@ describe("trace-reducer-v2", () => {
     expect(trace.steps).toHaveLength(0);
   });
 
+  it("drops v3-only tab switch steps", () => {
+    const trace = buildTraceV2({
+      steps: [
+        {
+          op: "switch_tab",
+          preStateId: "s1",
+          postStateId: "s2",
+          page_url: "https://example.com/second",
+        },
+      ],
+      startedAt: "2026-01-01T00:00:00.000Z",
+      startUrl: "https://example.com/",
+    });
+
+    expect(trace.steps).toHaveLength(0);
+  });
+
   it("maps captureTarget to v2 target with required tag", () => {
     const steps: DraftTraceStep[] = [
       {

apps/extension/src/lib/record-observation.ts

@@ -26,6 +26,7 @@ export interface LastSettledObservation {
 /** A post-action observation that has been queued but not yet written down. */
 interface PendingSettle {
   draftIndex: number;
+  tabId: number;
   /** Set when a newer action has already decided where this step landed. */
   cancelled: boolean;
 }
@@ -40,6 +41,7 @@ export interface PendingRedirectLanding {
 export interface RecordingObservationState {
   stateRegistry: Map<string, StateRegistryEntry>;
   lastSettled: LastSettledObservation | null;
+  settledByTab: Map<number, LastSettledObservation>;
   maxPageTokens: number;
   redactValues: boolean;
   lastCaptureAtMs: number;
@@ -67,6 +69,7 @@ export function createObservationState(options?: {
   return {
     stateRegistry: new Map(),
     lastSettled: null,
+    settledByTab: new Map(),
     maxPageTokens: options?.maxPageTokens ?? DEFAULT_MAX_PAGE_TOKENS,
     redactValues: options?.redactValues ?? false,
     lastCaptureAtMs: 0,
@@ -134,6 +137,7 @@ export async function captureAndRegisterObservation(
     vomText: rendered.text,
   };
   obs.lastSettled = settled;
+  obs.settledByTab.set(tabId, settled);
   return settled;
 }
 
@@ -499,11 +503,13 @@ export async function settleUnsettledDrafts(
 function supersedeEarlierSettles(
   obs: RecordingObservationState,
   draftIndex: number,
+  tabId: number,
   steps: DraftTraceStep[],
 ): void {
   const landing = steps[draftIndex]?.preStateId;
   for (const [index, pending] of obs.settles) {
     if (index >= draftIndex) continue;
+    if (pending.tabId !== tabId) continue;
     pending.cancelled = true;
     obs.settles.delete(index);
 
@@ -527,14 +533,14 @@ export function scheduleDraftSettle(
   tabsApi: ChromeTabsApi,
   steps: DraftTraceStep[],
 ): void {
-  supersedeEarlierSettles(obs, draftIndex, steps);
+  supersedeEarlierSettles(obs, draftIndex, tabId, steps);
 
   // Rescheduling the same step (a navigation showed up after the action)
   // replaces the pending observation rather than racing it.
   const superseded = obs.settles.get(draftIndex);
   if (superseded) superseded.cancelled = true;
 
-  const pending: PendingSettle = { draftIndex, cancelled: false };
+  const pending: PendingSettle = { draftIndex, tabId, cancelled: false };
   obs.settles.set(draftIndex, pending);
 
   enqueueSettle(obs, async () => {

apps/extension/src/lib/trace-reducer-v2.ts

@@ -85,7 +85,7 @@ function shouldIncludeDraft(step: DraftTraceStep): boolean {
   // `trace_version` omitted means a pre-v3 client. Released v2 readers
   // (including cli-v0.1.10) do not have hover in their tagged Step enum,
   // so emitting it makes the entire trace fail to deserialize.
-  if (step.op === "scroll" || step.op === "hover") return false;
+  if (step.op === "scroll" || step.op === "hover" || step.op === "switch_tab") return false;
   if (step.op === "fill" && !(step.value ?? "").trim() && !step.redacted) return false;
   if (step.op === "press" && !shouldRecordPress(step.key, step.modifiers)) return false;
   return true;
@@ -260,6 +260,7 @@ function toV2Step(
       };
     }
     case "scroll":
+    case "switch_tab":
       return null;
   }
 }

apps/extension/src/lib/trace-reducer.ts

@@ -152,6 +152,8 @@ function toV3Step(draft: DraftTraceStep, id: number): StepV3 | null {
         to: draft.url,
         cause: navigateCauseForDraft(draft),
       };
+    case "switch_tab":
+      return { op: "switch_tab", ...common };
     case "click":
       return { op: "click", ...common, target: draft.target };
     case "hover":