test(perf): avoid compaction hook plugin metadata scans

src/agents/pi-embedded-runner/compact.hooks.harness.ts

@@ -1,4 +1,5 @@
 import { vi, type Mock } from "vitest";
+import type { PluginMetadataSnapshot } from "../../plugins/plugin-metadata-snapshot.js";
 import { clearAgentHarnesses } from "../harness/registry.js";
 import type { CompactionTranscriptRotation } from "./compaction-successor-transcript.js";
 
@@ -105,6 +106,45 @@ export const rotateTranscriptAfterCompactionMock: Mock<
   rotated: false,
 }));
 
+const emptyPluginMetadataSnapshot: PluginMetadataSnapshot = {
+  policyHash: "",
+  index: {
+    version: 1,
+    hostContractVersion: "test",
+    compatRegistryVersion: "test",
+    migrationVersion: 1,
+    policyHash: "",
+    generatedAtMs: 1,
+    installRecords: {},
+    plugins: [],
+    diagnostics: [],
+  },
+  registryDiagnostics: [],
+  manifestRegistry: { plugins: [], diagnostics: [] },
+  plugins: [],
+  diagnostics: [],
+  byPluginId: new Map(),
+  normalizePluginId: (pluginId: string) => pluginId,
+  owners: {
+    channels: new Map(),
+    channelConfigs: new Map(),
+    providers: new Map(),
+    modelCatalogProviders: new Map(),
+    cliBackends: new Map(),
+    setupProviders: new Map(),
+    commandAliases: new Map(),
+    contracts: new Map(),
+  },
+  metrics: {
+    registrySnapshotMs: 0,
+    manifestRegistryMs: 0,
+    ownerMapsMs: 0,
+    totalMs: 0,
+    indexPluginCount: 0,
+    manifestPluginCount: 0,
+  },
+};
+
 export function resetCompactSessionStateMocks(): void {
   sanitizeSessionHistoryMock.mockReset();
   sanitizeSessionHistoryMock.mockImplementation(async (params: { messages: unknown[] }) => {
@@ -211,6 +251,10 @@ export async function loadCompactHooksHarness(): Promise<{
     ensureRuntimePluginsLoaded,
   }));
 
+  vi.doMock("../../plugins/current-plugin-metadata-snapshot.js", () => ({
+    getCurrentPluginMetadataSnapshot: () => emptyPluginMetadataSnapshot,
+  }));
+
   vi.doMock("../harness/selection.js", () => ({
     maybeCompactAgentHarnessSession: maybeCompactAgentHarnessSessionMock,
   }));