fix(plugins): Reserve core feature names for manifest-only plugins

Runtime validation only saw registrations with runtime hooks, so an inline
or YAML manifest could still claim memory or briefs and enter the plugin
catalog next to the core feature. Check reserved names at the shared
manifest registration boundary as well.

Refs #1861

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

Author: dcramer

packages/junior/src/chat/plugins/registry.ts

@@ -2,6 +2,7 @@ import { readFileSync, readdirSync, statSync } from "node:fs";
 import path from "node:path";
 import type { CredentialBroker } from "@/chat/credentials/broker";
 import { pluginRoots } from "@/chat/discovery";
+import { isCoreFeatureName } from "@/chat/plugins/core-features";
 import { logInfo, logWarn, setSpanAttributes } from "@/chat/logging";
 import { parseInlinePluginManifest, parsePluginManifest } from "./manifest";
 import { createOAuthBearerBroker } from "./auth/oauth-bearer-broker";
@@ -108,6 +109,11 @@ function registerPluginManifest(
   if (state.pluginsByName.has(manifest.name)) {
     throw new Error(`Duplicate plugin name "${manifest.name}"`);
   }
+  if (isCoreFeatureName(manifest.name)) {
+    throw new Error(
+      `Plugin name "${manifest.name}" is reserved for a Junior core feature`,
+    );
+  }
 
   for (const domain of providerDomains(manifest)) {
     const owner = state.domainToPlugin.get(domain);
@@ -511,7 +517,9 @@ export function createPluginCatalogRuntime(): PluginCatalogRuntime {
           commands.push({
             cmd: command.cmd,
             ...(command.args ? { args: [...command.args] } : undefined),
-            ...(command.sudo !== undefined ? { sudo: command.sudo } : undefined),
+            ...(command.sudo !== undefined
+              ? { sudo: command.sudo }
+              : undefined),
           });
         }
       }

packages/junior/tests/unit/plugins/core-features.test.ts

@@ -7,6 +7,11 @@ import {
   validatePlugins,
 } from "@/chat/plugins/agent-hooks";
 import { getCoreFeatures, setCoreFeatures } from "@/chat/plugins/core-features";
+import { createPluginCatalogRuntime } from "@/chat/plugins/registry";
+import {
+  defineJuniorPlugins,
+  pluginCatalogConfigFromPluginSet,
+} from "@/plugins";
 
 afterEach(() => {
   setCoreFeatures([]);
@@ -76,5 +81,24 @@ describe("core features", () => {
     expect(() => validatePlugins([plugin])).toThrow(
       'Plugin name "briefs" is reserved for a Junior core feature',
     );
+
+    // Manifest-only plugins skip runtime validation and enter the catalog.
+    const catalog = createPluginCatalogRuntime();
+    catalog.setConfig(
+      pluginCatalogConfigFromPluginSet(
+        defineJuniorPlugins([
+          defineJuniorPlugin({
+            manifest: {
+              name: "memory",
+              displayName: "Other Memory",
+              description: "Not core memory",
+            },
+          }),
+        ]),
+      ),
+    );
+    expect(() => catalog.getProviders()).toThrow(
+      'Plugin name "memory" is reserved for a Junior core feature',
+    );
   });
 });