Fix double-close race condition when handling dead clients

lua/amp/init.lua

@@ -33,7 +33,8 @@ function M._on_client_connect()
 	M.state.connected = true
 
 	if not was_connected then
-		logger.info("init", "Connected to Amp")
+		-- Use print() directly to avoid [INFO] init: prefix from logger
+		print("● Connected to Amp CLI")
 	end
 end
 

lua/amp/server/client.lua

@@ -208,25 +208,36 @@ end
 ---@param code number|nil Close code (default: 1000)
 ---@param reason string|nil Close reason
 function M.close_client(client, code, reason)
-	if client.state == "closed" or client.state == "closing" then
+	-- Already closing/closed? Bail early.
+	if client.state == "closed" or client.tcp_handle:is_closing() then
 		return
 	end
 
 	code = code or 1000
 	reason = reason or ""
 
-	if client.handshake_complete then
+	client.state = "closing"
+
+	-- If handshake complete and code is allowed to be sent, send a Close frame
+	-- Per RFC 6455, code 1006 MUST NOT be sent in a Close frame
+	local can_send_close = client.handshake_complete and code ~= 1006
+
+	if can_send_close then
 		local close_frame = frame.create_close_frame(code, reason)
-		client.tcp_handle:write(close_frame, function()
+		client.tcp_handle:write(close_frame, function(err)
+			-- Regardless of write result, ensure handle is closed exactly once
+			if not client.tcp_handle:is_closing() then
+				client.tcp_handle:close()
+			end
 			client.state = "closed"
-			client.tcp_handle:close()
 		end)
 	else
+		-- For abnormal closure (1006) or no handshake, just drop TCP immediately
+		if not client.tcp_handle:is_closing() then
+			client.tcp_handle:close()
+		end
 		client.state = "closed"
-		client.tcp_handle:close()
 	end
-
-	client.state = "closing"
 end
 
 ---Check if a client connection is alive

lua/amp/server/tcp.lua

@@ -162,7 +162,11 @@ function M._remove_client(server, client)
 		server.clients[client.id] = nil
 
 		if not client.tcp_handle:is_closing() then
+			client.state = "closing"
 			client.tcp_handle:close()
+			-- Note: close() is async in libuv, but we mark as "closed" immediately
+			-- since the client is removed from the active list and won't be used again
+			client.state = "closed"
 		end
 	end
 end
@@ -264,10 +268,10 @@ function M.start_ping_timer(server, interval)
 				if client_manager.is_client_alive(client, interval * 2) then
 					client_manager.send_ping(client, "ping")
 				else
-					-- Client appears dead, close it
-					server.on_error("Client " .. client.id .. " appears dead, closing")
-					client_manager.close_client(client, 1006, "Connection timeout")
+					-- Client appears dead, drop the connection (no Close frame for 1006)
+					server.on_error(("Client %s appears dead, closing"):format(client.id))
 					M._remove_client(server, client)
+					server.on_disconnect(client, 1006, "Connection timeout")
 				end
 			end
 		end