test(plugins): verify repeated timeline IDs in a real browser

Exercise the installed plugin through the real daemon and chat viewport. Read the oldest virtualized replacement before and after reload, using actual browser row heights instead of extending the legacy JSDOM harness.

packages/app/src/agent-stream/strategy-web.test.tsx

@@ -10,7 +10,6 @@ import { RetainedPanelActivity } from "@/components/retained-panel";
 import { reduceStreamUpdate, type StreamItem } from "@/types/stream";
 import type { StreamRenderInput, StreamSegmentRenderers, StreamViewportHandle } from "./strategy";
 import { createWebStreamStrategy } from "./strategy-web";
-import { projectPluginTimelineItems } from "@/plugins/timeline/projection";
 
 vi.hoisted(() => {
   Object.defineProperty(window, "matchMedia", {
@@ -56,11 +55,10 @@ function createRenderers(onRowRender: () => void): StreamSegmentRenderers {
   };
 }
 
-function MeasuredTestRow({ item, measuredHeight }: { item: StreamItem; measuredHeight?: number }) {
+function MeasuredTestRow({ item }: { item: StreamItem }) {
   const [loaded, setLoaded] = React.useState(false);
   const load = React.useCallback(() => setLoaded(true), []);
-  const height =
-    measuredHeight ?? (item.kind === "user_message" && item.text === "grown" ? 120 : 24);
+  const height = item.kind === "user_message" && item.text === "grown" ? 120 : 24;
   const measure = React.useCallback(
     (node: HTMLDivElement | null) => {
       if (!node?.parentElement) return;
@@ -254,75 +252,6 @@ describe("createWebStreamStrategy", () => {
     expect(rowRenderCount.mock.calls.length).toBeLessThanOrEqual(historyVirtualized.length);
   });
 
-  it("settles row measurement when a plugin reuses output IDs across source messages", () => {
-    const strategy = createWebStreamStrategy({ isMobileBreakpoint: true });
-    container = document.createElement("div");
-    document.body.appendChild(container);
-    root = createRoot(container);
-    const renderRow = (rowItem: StreamItem) => (
-      <MeasuredTestRow
-        item={rowItem}
-        measuredHeight={rowItem.kind === "plugin" && rowItem.sourceId === "message-2" ? 120 : 24}
-      />
-    );
-    const historyVirtualized = projectPluginTimelineItems(
-      [userMessage(0), userMessage(1), userMessage(2), userMessage(3), userMessage(4)],
-      ({ sourceId }) =>
-        sourceId === "message-2" || sourceId === "message-3"
-          ? [
-              {
-                type: "plugin",
-                id: "part-0",
-                pluginId: "split",
-                kind: "part",
-                version: 1,
-                data: null,
-              },
-            ]
-          : undefined,
-    );
-    const input: StreamRenderInput = {
-      agentId: "agent",
-      segments: { historyVirtualized, historyMounted: [], liveHead: [] },
-      boundary: { hasVirtualizedHistory: true, hasMountedHistory: false, hasLiveHead: false },
-      renderers: {
-        renderHistoryVirtualizedRow: renderRow,
-        renderHistoryMountedRow: renderRow,
-        renderLiveHeadRow: renderRow,
-        renderLiveAuxiliary: () => null,
-      },
-      listEmptyComponent: null,
-      viewportRef: React.createRef<StreamViewportHandle>(),
-      routeBottomAnchorRequest: null,
-      isAuthoritativeHistoryReady: true,
-      onNearBottomChange: () => {},
-      onNearHistoryStart: () => true,
-      isLoadingOlderHistory: false,
-      hasOlderHistory: false,
-      olderHistoryProgressKey: null,
-      scrollEnabled: true,
-      listStyle: null,
-      baseListContentContainerStyle: null,
-      forwardListContentContainerStyle: null,
-      contentMaxWidth: DEFAULT_CONTENT_MAX_WIDTH,
-    };
-
-    // Before the fix, this render aborted with "Maximum update depth exceeded".
-    act(() => root?.render(strategy.render(input)));
-
-    const rows = [...container.querySelectorAll<HTMLElement>("[data-history-row-id]")];
-    expect(rows.map((row) => row.dataset.historyRowId)).toEqual(
-      historyVirtualized.map((row) => row.id),
-    );
-    expect(rows.map((row) => row.style.transform)).toEqual([
-      "translateY(0px)",
-      "translateY(24px)",
-      "translateY(48px)",
-      "translateY(168px)",
-      "translateY(192px)",
-    ]);
-  });
-
   it("retains a row's DOM and local state when recent history becomes virtualized", () => {
     const strategy = createWebStreamStrategy({ isMobileBreakpoint: true });
     container = document.createElement("div");