feat: 写指令也短读0.3s捕获机器的ERR回包

之前 expect_reply=False 直接关 socket, 机器若回 ERR 完全感知不到,
表现就是"接口200但实际没动作"。改为写完后短读最多一行, 拿到
ERR/'!' 开头直接报错; 超时则照旧视为成功放行。

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/cm/coder.py

@@ -27,8 +27,7 @@ class CoderClient:
         try:
             with socket.create_connection((self.ip, self.port), timeout=self.timeout) as s:
                 s.sendall(frame)
-                if not expect_reply:
-                    return b""
+                if expect_reply:
                     buf = b""
                     while CR not in buf:
                         chunk = s.recv(256)
@@ -36,6 +35,24 @@ class CoderClient:
                             break
                         buf += chunk
                     return buf
+                # 写指令: 短暂等待, 捕获机器拒绝(ERR/!); 超时则视为成功
+                s.settimeout(0.3)
+                try:
+                    buf = b""
+                    while CR not in buf:
+                        chunk = s.recv(256)
+                        if not chunk:
+                            break
+                        buf += chunk
+                except socket.timeout:
+                    buf = b""
+                if buf:
+                    text = buf.rstrip(b"\r\n").decode("latin-1", errors="replace")
+                    if text.startswith("ERR") or text.startswith("!"):
+                        raise CoderError(f"喷码机拒绝指令 {frame!r}: {text}")
+                return b""
+        except CoderError:
+            raise
         except (socket.timeout, OSError) as e:
             raise CoderError(f"喷码通讯失败 {self.ip}:{self.port} - {e}")