fix(api): return 400 on path-variable type mismatch instead of 500

mateclaw-server/src/main/java/vip/mate/exception/GlobalExceptionHandler.java

@@ -11,6 +11,7 @@ import org.springframework.validation.BindException;
 import org.springframework.web.bind.annotation.ExceptionHandler;
 import org.springframework.web.bind.annotation.RestControllerAdvice;
 import org.springframework.web.context.request.async.AsyncRequestTimeoutException;
+import org.springframework.web.method.annotation.MethodArgumentTypeMismatchException;
 import org.springframework.web.servlet.resource.NoResourceFoundException;
 import vip.mate.common.result.R;
 import vip.mate.i18n.I18nService;
@@ -97,6 +98,22 @@ public class GlobalExceptionHandler {
         return ResponseEntity.badRequest().body(R.fail(400, msg));
     }
 
+    /**
+     * A path variable or request parameter could not be coerced into the
+     * handler's declared type (e.g. a non-numeric segment on an {@code /{id}}
+     * route bound to {@code Long}). This is a malformed client request, not a
+     * server fault, so it must surface as 400 — never a 500 with a full stack
+     * trace from the catch-all handler below.
+     */
+    @ExceptionHandler(MethodArgumentTypeMismatchException.class)
+    public ResponseEntity<R<Void>> handleTypeMismatch(MethodArgumentTypeMismatchException e,
+                                                      HttpServletRequest request) {
+        String required = e.getRequiredType() != null ? e.getRequiredType().getSimpleName() : "expected type";
+        String msg = "Invalid value for parameter '" + e.getName() + "': expected " + required;
+        log.warn("Argument type mismatch: {} {} - {}", request.getMethod(), request.getRequestURI(), msg);
+        return ResponseEntity.badRequest().body(R.fail(400, msg));
+    }
+
     @ExceptionHandler(NoResourceFoundException.class)
     public ResponseEntity<R<Void>> handleNoResourceFound(NoResourceFoundException e,
                                                          HttpServletRequest request) {

mateclaw-server/src/test/java/vip/mate/exception/GlobalExceptionHandlerTypeMismatchTest.java

@@ -0,0 +1,62 @@
+package vip.mate.exception;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.springframework.test.web.servlet.MockMvc;
+import org.springframework.test.web.servlet.setup.MockMvcBuilders;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.RestController;
+import vip.mate.common.result.R;
+import vip.mate.i18n.I18nService;
+
+import static org.mockito.Mockito.mock;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+
+/**
+ * Verifies that a non-coercible path variable on a typed route surfaces as a
+ * clean HTTP 400 (handled by {@link GlobalExceptionHandler}) instead of leaking
+ * a 500 with a full stack trace from the catch-all handler.
+ */
+class GlobalExceptionHandlerTypeMismatchTest {
+
+    private MockMvc mockMvc;
+
+    @BeforeEach
+    void setUp() {
+        I18nService i18n = mock(I18nService.class);
+        mockMvc = MockMvcBuilders.standaloneSetup(new ProbeController())
+                .setControllerAdvice(new GlobalExceptionHandler(i18n))
+                .build();
+    }
+
+    @Test
+    @DisplayName("Non-numeric segment on a Long {id} route returns 400, not 500.")
+    void nonNumericIdReturns400() throws Exception {
+        mockMvc.perform(get("/probe/status"))
+                .andExpect(status().isBadRequest())
+                .andExpect(jsonPath("$.code").value(400))
+                .andExpect(jsonPath("$.msg").value("Invalid value for parameter 'id': expected Long"));
+    }
+
+    @Test
+    @DisplayName("A valid numeric id still resolves the handler normally.")
+    void numericIdReturns200() throws Exception {
+        mockMvc.perform(get("/probe/123"))
+                .andExpect(status().isOk())
+                .andExpect(jsonPath("$.code").value(200))
+                .andExpect(jsonPath("$.data").value(123));
+    }
+
+    /** Minimal stand-in for any controller with a {@code Long} path variable. */
+    @RestController
+    static class ProbeController {
+        @GetMapping("/probe/{id}")
+        R<Long> probe(@PathVariable Long id) {
+            return R.ok(id);
+        }
+    }
+}