Remove unused ZMQ command receiver (port 6131)

Service control migrated to SSH, command receiver no longer needed.
- Remove command_receiver Socket from ZmqHandler
- Remove try_receive_command method
- Remove AgentCommand enum
- Remove command_port from ZmqConfig

agent/src/communication/mod.rs

@@ -5,10 +5,9 @@ use zmq::{Context, Socket, SocketType};
 
 use crate::config::ZmqConfig;
 
-/// ZMQ communication handler for publishing metrics and receiving commands
+/// ZMQ communication handler for publishing metrics
 pub struct ZmqHandler {
     publisher: Socket,
-    command_receiver: Socket,
 }
 
 impl ZmqHandler {
@@ -26,20 +25,8 @@ impl ZmqHandler {
         publisher.set_sndhwm(1000)?; // High water mark for outbound messages
         publisher.set_linger(1000)?; // Linger time on close
 
-        // Create command receiver socket (PULL socket to receive commands from dashboard)
-        let command_receiver = context.socket(SocketType::PULL)?;
-        let cmd_bind_address = format!("tcp://{}:{}", config.bind_address, config.command_port);
-        command_receiver.bind(&cmd_bind_address)?;
-
-        info!("ZMQ command receiver bound to {}", cmd_bind_address);
-
-        // Set non-blocking mode for command receiver
-        command_receiver.set_rcvtimeo(0)?; // Non-blocking receive
-        command_receiver.set_linger(1000)?;
-
         Ok(Self {
             publisher,
-            command_receiver,
         })
     }
 
@@ -65,36 +52,4 @@ impl ZmqHandler {
         Ok(())
     }
 
-    /// Try to receive a command (non-blocking)
-    pub fn try_receive_command(&self) -> Result<Option<AgentCommand>> {
-        match self.command_receiver.recv_bytes(zmq::DONTWAIT) {
-            Ok(bytes) => {
-                debug!("Received command message ({} bytes)", bytes.len());
-
-                let command: AgentCommand = serde_json::from_slice(&bytes)
-                    .map_err(|e| anyhow::anyhow!("Failed to deserialize command: {}", e))?;
-
-                debug!("Parsed command: {:?}", command);
-                Ok(Some(command))
-            }
-            Err(zmq::Error::EAGAIN) => {
-                // No message available (non-blocking)
-                Ok(None)
-            }
-            Err(e) => Err(anyhow::anyhow!("ZMQ receive error: {}", e)),
-        }
-    }
-}
-
-/// Commands that can be sent to the agent
-#[derive(Debug, Clone, serde::Deserialize, serde::Serialize)]
-pub enum AgentCommand {
-    /// Request immediate metric collection
-    CollectNow,
-    /// Change collection interval
-    SetInterval { seconds: u64 },
-    /// Enable/disable a collector
-    ToggleCollector { name: String, enabled: bool },
-    /// Request status/health check
-    Ping,
 }

agent/src/config/mod.rs

@@ -20,7 +20,6 @@ pub struct AgentConfig {
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct ZmqConfig {
     pub publisher_port: u16,
-    pub command_port: u16,
     pub bind_address: String,
     pub transmission_interval_seconds: u64,
     /// Heartbeat transmission interval in seconds for host connectivity detection