fix(mcp): add --force flag to 'mcp add' command for overwriting existing servers

Fixes bounty issue #1620

The 'mcp add' command now supports a --force flag that allows overwriting
an existing MCP server configuration. When --force is specified and the
server already exists, the old configuration is removed before adding
the new one. Without --force, the error message now suggests using
--force as an alternative to manually removing the server first.

Author: factorydroid

cortex-cli/src/mcp_cmd.rs

@@ -308,6 +308,10 @@ pub struct AddArgs {
     /// Name for the MCP server configuration.
     pub name: String,
 
+    /// Force overwrite if server already exists.
+    #[arg(short, long)]
+    pub force: bool,
+
     #[command(flatten)]
     pub transport_args: AddMcpTransportArgs,
 }
@@ -492,6 +496,34 @@ fn get_mcp_server(name: &str) -> Result<Option<toml::Value>> {
     Ok(servers.get(name).cloned())
 }
 
+/// Remove a specific MCP server from config (used by --force).
+fn remove_mcp_server_from_config(name: &str) -> Result<()> {
+    let cortex_home = get_cortex_home_result()?;
+    let config_path = cortex_home.join("config.toml");
+
+    if !config_path.exists() {
+        return Ok(());
+    }
+
+    let content = std::fs::read_to_string(&config_path)
+        .with_context(|| format!("failed to read config: {}", config_path.display()))?;
+
+    let mut config: toml::Value =
+        toml::from_str(&content).with_context(|| "failed to parse config")?;
+
+    if let Some(mcp_servers) = config.get_mut("mcp_servers").and_then(|v| v.as_table_mut()) {
+        mcp_servers.remove(name);
+    }
+
+    let new_content =
+        toml::to_string_pretty(&config).with_context(|| "failed to serialize config")?;
+
+    std::fs::write(&config_path, new_content)
+        .with_context(|| format!("failed to write config: {}", config_path.display()))?;
+
+    Ok(())
+}
+
 async fn run_list(args: ListArgs) -> Result<()> {
     let servers = get_mcp_servers()?;
 
@@ -662,18 +694,25 @@ async fn run_get(args: GetArgs) -> Result<()> {
 async fn run_add(args: AddArgs) -> Result<()> {
     let AddArgs {
         name,
+        force,
         transport_args,
     } = args;
 
     validate_server_name(&name)?;
 
     // Check if server already exists
     if get_mcp_server(&name)?.is_some() {
-        bail!(
-            "MCP server '{}' already exists. Use 'Cortex mcp remove {}' first.",
-            name,
-            name
-        );
+        if force {
+            // Remove existing server before adding the new one
+            remove_mcp_server_from_config(&name)?;
+            println!("Replacing existing MCP server '{name}'...");
+        } else {
+            bail!(
+                "MCP server '{}' already exists. Use --force to overwrite or 'Cortex mcp remove {}' first.",
+                name,
+                name
+            );
+        }
     }
 
     let cortex_home = get_cortex_home_result()?;