Agent Skills: Implement /skills reload (#15865)

packages/core/src/config/config.ts

@@ -356,6 +356,7 @@ export interface ConfigParameters {
   disabledSkills?: string[];
   experimentalJitContext?: boolean;
   onModelChange?: (model: string) => void;
+  onReload?: () => Promise<{ disabledSkills?: string[] }>;
 }
 
 export class Config {
@@ -479,10 +480,13 @@ export class Config {
   private experimentsPromise: Promise<void> | undefined;
   private hookSystem?: HookSystem;
   private readonly onModelChange: ((model: string) => void) | undefined;
+  private readonly onReload:
+    | (() => Promise<{ disabledSkills?: string[] }>)
+    | undefined;
 
   private readonly enableAgents: boolean;
   private readonly skillsSupport: boolean;
-  private readonly disabledSkills: string[];
+  private disabledSkills: string[];
 
   private readonly experimentalJitContext: boolean;
   private contextManager?: ContextManager;
@@ -643,6 +647,7 @@ export class Config {
     this.projectHooks = params.projectHooks;
     this.experiments = params.experiments;
     this.onModelChange = params.onModelChange;
+    this.onReload = params.onReload;
 
     if (params.contextFileName) {
       setGeminiMdFilename(params.contextFileName);
@@ -1520,6 +1525,38 @@ export class Config {
     return this.skillsSupport;
   }
 
+  /**
+   * Reloads skills by re-discovering them from extensions and local directories.
+   */
+  async reloadSkills(): Promise<void> {
+    if (!this.skillsSupport) {
+      return;
+    }
+
+    if (this.onReload) {
+      const refreshed = await this.onReload();
+      this.disabledSkills = refreshed.disabledSkills ?? [];
+    }
+
+    await this.getSkillManager().discoverSkills(
+      this.storage,
+      this.getExtensions(),
+    );
+    this.getSkillManager().setDisabledSkills(this.disabledSkills);
+
+    // Re-register ActivateSkillTool to update its schema with the newly discovered skills
+    if (this.getSkillManager().getSkills().length > 0) {
+      this.getToolRegistry().registerTool(
+        new ActivateSkillTool(this, this.messageBus),
+      );
+    } else {
+      this.getToolRegistry().unregisterTool(ActivateSkillTool.Name);
+    }
+
+    // Notify the client that system instructions might need updating
+    await this.updateSystemInstructionIfInitialized();
+  }
+
   isInteractive(): boolean {
     return this.interactive;
   }