fix(agent): mcp command producing malformed mcp.json (#2345)

Author: dingfeli

crates/chat-cli/src/cli/agent/mcp_config.rs

@@ -32,8 +32,20 @@ impl McpServerConfig {
     }
 
     pub async fn save_to_file(&self, os: &Os, path: impl AsRef<Path>) -> eyre::Result<()> {
-        let json = serde_json::to_string_pretty(self)?;
+        let json = self.to_non_transparent_json_pretty()?;
         os.fs.write(path.as_ref(), json).await?;
         Ok(())
     }
+
+    /// Because we had annotated [McpServerConfig] with transparent, when writing the config alone
+    /// to its legacy location (as opposed to writing it along with its agent config), we would
+    /// need to call this function to stringify it otherwise we would be writing only the inner
+    /// hashmap.
+    fn to_non_transparent_json_pretty(&self) -> eyre::Result<String> {
+        let transparent_json = serde_json::to_value(self)?;
+        let non_transparent_json = serde_json::json!({
+            "mcpServers": transparent_json
+        });
+        Ok(serde_json::to_string_pretty(&non_transparent_json)?)
+    }
 }

crates/chat-cli/src/cli/mcp.rs

@@ -159,8 +159,7 @@ impl AddArgs {
                 }))?;
 
                 mcp_servers.mcp_servers.insert(self.name.clone(), tool);
-                let json = serde_json::to_string_pretty(&mcp_servers)?;
-                os.fs.write(&global_config_path, json).await?;
+                mcp_servers.save_to_file(os, &global_config_path).await?;
                 writeln!(
                     output,
                     "✓ Added MCP server '{}' to global config in {}\n",
@@ -220,8 +219,7 @@ impl RemoveArgs {
 
                 match config.mcp_servers.remove(&self.name) {
                     Some(_) => {
-                        let json = serde_json::to_string_pretty(&config)?;
-                        os.fs.write(&global_config_path, json).await?;
+                        config.save_to_file(os, &global_config_path).await?;
                         writeln!(
                             output,
                             "\n✓ Removed MCP server '{}' from global config (path {})\n",