test(plugins): mock install slot registry

src/cli/plugins-cli.install.test.ts

@@ -16,6 +16,7 @@ import {
   installPluginFromNpmSpec,
   installPluginFromPath,
   loadConfig,
+  loadPluginManifestRegistry,
   readConfigFileSnapshot,
   parseClawHubPluginSpec,
   recordHookInstall,
@@ -385,6 +386,10 @@ describe("plugins cli install", () => {
       plugins: [{ id: "alpha", kind: "provider" }],
       diagnostics: [],
     });
+    loadPluginManifestRegistry.mockReturnValue({
+      plugins: [{ id: "alpha", kind: "memory" }],
+      diagnostics: [],
+    });
     applyExclusiveSlotSelection.mockReturnValue({
       config: enabledCfg,
       warnings: ["slot adjusted"],