feat(Handler/proxy): Add initial Cocoon RPC proxy handler

- Introduces `proxy` module in Mountain's handler layer to mediate between Sky frontend and Cocoon extension host
- Implements `handle_ext_host_proxy` using Vine IPC to forward API calls to Cocoon sidecar process
- Provides basic argument handling and error wrapping for IPC communication
- Temporary process ID placeholder establishes pattern for future multi-instance extension host support

This foundational handler enables routing extension-related commands from Sky's VS Code-compatible UI through Mountain to the Cocoon shim layer, critical for Path A extension compatibility. The implementation leverages Land's Vine IPC layer while highlighting areas for future hardening (target process selection, payload validation).

Author: NikolaRHristov

Source/Library.rs

@@ -30,4 +30,6 @@ pub mod handlers {
 	pub mod process_mgmt;
 
 	pub mod protocol;
+
+	pub mod proxy;
 }

Source/handlers/proxy.rs

@@ -1,22 +1,26 @@
-use serde_json::{json, Value};
+use serde_json::{Value, json};
 use tauri::{AppHandle, Runtime, Window};
-use crate::vine; // Use the Vine IPC layer
 
-pub async fn handle_ext_host_proxy<R: Runtime>(
-    _app: AppHandle<R>,
-    _window: Window<R>,
-    args: Vec<Value>,
+// Use the Vine IPC layer
+use crate::vine;
+
+pub async fn handle_ext_host_proxy<R:Runtime>(
+	_app:AppHandle<R>,
+	_window:Window<R>,
+	args:Vec<Value>,
 ) -> Result<Value, String> {
-    println!("[Proxy Handler] Proxying call to Cocoon: {:?}", args);
-    // TODO: Identify target Cocoon process instance
-    let target_process_id = 1234; // Placeholder
+	println!("[Proxy Handler] Proxying call to Cocoon: {:?}", args);
+
+	// TODO: Identify target Cocoon process instance
+	// Placeholder
+	let target_process_id = 1234;
 
-    // TODO: Robust arg handling - expect specific structure for API call
-    let request_payload = args.get(0).cloned().unwrap_or(json!(null));
+	// TODO: Robust arg handling - expect specific structure for API call
+	let request_payload = args.get(0).cloned().unwrap_or(json!(null));
 
-    // Use Vine to send the request and await response
-    match vine::send_to_sidecar(target_process_id, request_payload).await {
-        Ok(response) => Ok(response),
-        Err(e) => Err(format!("Cocoon IPC Error: {}", e)),
-    }
+	// Use Vine to send the request and await response
+	match vine::send_to_sidecar(target_process_id, request_payload).await {
+		Ok(response) => Ok(response),
+		Err(e) => Err(format!("Cocoon IPC Error: {}", e)),
+	}
 }