feat(cli): add mcp prompt support via slash commands (#1323)

crates/goose/src/agents/agent.rs

@@ -1,3 +1,5 @@
+use std::collections::HashMap;
+
 use anyhow::Result;
 use async_trait::async_trait;
 use futures::stream::BoxStream;
@@ -6,6 +8,8 @@ use serde_json::Value;
 use super::extension::{ExtensionConfig, ExtensionResult};
 use crate::message::Message;
 use crate::providers::base::ProviderUsage;
+use mcp_core::prompt::Prompt;
+use mcp_core::protocol::GetPromptResult;
 
 /// Core trait defining the behavior of an Agent
 #[async_trait]
@@ -37,4 +41,11 @@ pub trait Agent: Send + Sync {
 
     /// Override the system prompt with custom text
     async fn override_system_prompt(&mut self, template: String);
+
+    /// Lists all prompts from all extensions
+    async fn list_extension_prompts(&self) -> HashMap<String, Vec<Prompt>>;
+
+    /// Get a prompt result with the given name and arguments
+    /// Returns the prompt text that would be used as user input
+    async fn get_prompt(&self, name: &str, arguments: Value) -> Result<GetPromptResult>;
 }