Load and use MCP server prompts as slash commands in the CLI (#4828)

Co-authored-by: harold <haroldmciver@google.com>
Co-authored-by: N. Taylor Mullen <ntaylormullen@google.com>

packages/core/src/prompts/prompt-registry.ts

@@ -0,0 +1,56 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { DiscoveredMCPPrompt } from '../tools/mcp-client.js';
+
+export class PromptRegistry {
+  private prompts: Map<string, DiscoveredMCPPrompt> = new Map();
+
+  /**
+   * Registers a prompt definition.
+   * @param prompt - The prompt object containing schema and execution logic.
+   */
+  registerPrompt(prompt: DiscoveredMCPPrompt): void {
+    if (this.prompts.has(prompt.name)) {
+      const newName = `${prompt.serverName}_${prompt.name}`;
+      console.warn(
+        `Prompt with name "${prompt.name}" is already registered. Renaming to "${newName}".`,
+      );
+      this.prompts.set(newName, { ...prompt, name: newName });
+    } else {
+      this.prompts.set(prompt.name, prompt);
+    }
+  }
+
+  /**
+   * Returns an array of all registered and discovered prompt instances.
+   */
+  getAllPrompts(): DiscoveredMCPPrompt[] {
+    return Array.from(this.prompts.values()).sort((a, b) =>
+      a.name.localeCompare(b.name),
+    );
+  }
+
+  /**
+   * Get the definition of a specific prompt.
+   */
+  getPrompt(name: string): DiscoveredMCPPrompt | undefined {
+    return this.prompts.get(name);
+  }
+
+  /**
+   * Returns an array of prompts registered from a specific MCP server.
+   */
+  getPromptsByServer(serverName: string): DiscoveredMCPPrompt[] {
+    const serverPrompts: DiscoveredMCPPrompt[] = [];
+    for (const prompt of this.prompts.values()) {
+      if (prompt.serverName === serverName) {
+        serverPrompts.push(prompt);
+      }
+    }
+    return serverPrompts.sort((a, b) => a.name.localeCompare(b.name));
+  }
+}