fix: satisfy browser tab landing guards

ui/src/components/browser/browser-panel-controller-input.test.ts

@@ -663,7 +663,7 @@ describe("BrowserPanelController capture and input ownership", () => {
     const previousUrl = "https://example.test/previous";
     const { client, request } = createBrowserClient(async (envelope) => {
       if (envelope.path === "/act") {
-        const fn = String(envelope.body?.fn ?? "");
+        const fn = typeof envelope.body?.fn === "string" ? envelope.body.fn : "";
         return fn.includes("history.go")
           ? { result: true }
           : createBrowserPanelTestMetrics(previousUrl, "Previous");

ui/src/components/browser/browser-panel-controller.ts

@@ -37,6 +37,7 @@ import {
   paintBrowserPanelOverlay,
   type BrowserPanelView,
 } from "./browser-panel-surface.ts";
+import { reconcileCapturedTab } from "./browser-panel-tabs.ts";
 import { normalizeBrowserUrlDraft } from "./browser-url.ts";
 
 const INSPECT_THROTTLE_MS = 120;
@@ -223,19 +224,9 @@ export class BrowserPanelController implements ReactiveController {
         shot.url && observedMetrics?.url && shot.url !== observedMetrics.url
           ? null
           : observedMetrics;
-      const tabIndex = this.tabs.findIndex((tab) => tab.id === targetId);
-      const tab = this.tabs[tabIndex];
-      if (tab) {
-        // Tab snapshots can lag history and in-page navigation. Keep the active
-        // tab's stable identity aligned with the document this capture owns.
-        const url = metrics?.url || shot.url || tab.url;
-        const title = metrics ? metrics.title : tab.title;
-        if (url !== tab.url || title !== tab.title) {
-          const tabs = [...this.tabs];
-          tabs[tabIndex] = { ...tab, title, url };
-          this.setState("tabs", tabs);
-        }
-      }
+      // Tab snapshots can lag history and in-page navigation. Keep the stable
+      // identity aligned with the document this capture owns.
+      this.setState("tabs", reconcileCapturedTab(this.tabs, targetId, metrics, shot.url));
       this.setState("view", { targetId, dataUrl, image, url: shot.url, metrics });
       if (!this.urlDraftEditing && shot.url) {
         this.setState("urlDraft", shot.url);

ui/src/components/browser/browser-panel-tabs.ts

@@ -1,6 +1,24 @@
 import { t } from "../../i18n/index.ts";
 import { renderPanelTabStrip, type PanelTabStripTab } from "../panel-tab-strip.ts";
-import type { BrowserPanelTab } from "./browser-client.ts";
+import type { BrowserPageMetrics, BrowserPanelTab } from "./browser-client.ts";
+
+export function reconcileCapturedTab(
+  tabs: BrowserPanelTab[],
+  targetId: string,
+  metrics: BrowserPageMetrics | null,
+  screenshotUrl: string,
+): BrowserPanelTab[] {
+  const tab = tabs.find((entry) => entry.id === targetId);
+  if (!tab) {
+    return tabs;
+  }
+  const title = metrics?.title ?? tab.title;
+  const url = metrics?.url || screenshotUrl || tab.url;
+  if (title === tab.title && url === tab.url) {
+    return tabs;
+  }
+  return tabs.map((entry) => (entry.id === targetId ? { ...entry, title, url } : entry));
+}
 
 function tabLabel(tab: BrowserPanelTab): string {
   if (tab.title.trim()) {