feat(health): 添加服务器健康检查端点 /_health

- 新增 /_health 路由，返回 JSON 格式的服务器状态
- 包含：uptime、活跃连接数、最大连接数、插件列表、中间件列表
- 中间件注册表新增 cocoon_middleware_list() 查询 API
- 集成测试新增 7 项健康检查验证（状态码、JSON 字段、HEAD 支持）
- 编译零警告，142 个单元测试 + 75 项集成测试全部通过

middleware.c

@@ -242,6 +242,21 @@ void cocoon_middleware_cleanup(void) {
     pthread_mutex_unlock(&g_rate_limit_mutex);
 }
 
+int cocoon_middleware_list(char names[][32], int count) {
+    if (!names || count <= 0) return 0;
+    int n = 0;
+    for (int i = 0; i < g_count && n < count; i++) {
+        if (g_registry[i].active) {
+            size_t len = strlen(g_registry[i].name);
+            if (len > 31) len = 31;
+            memcpy(names[n], g_registry[i].name, len);
+            names[n][len] = '\0';
+            n++;
+        }
+    }
+    return n;
+}
+
 /* === 内置中间件 === */
 
 int cocoon_middleware_cors(http_request_t *req, cocoon_socket_t fd, void *user_data) {

middleware.h

@@ -130,6 +130,17 @@ int cocoon_middleware_basic_auth(http_request_t *req, cocoon_socket_t fd, void *
  */
 int cocoon_middleware_rate_limit(http_request_t *req, cocoon_socket_t fd, void *user_data);
 
+/**
+ * cocoon_middleware_list - 获取已注册中间件名称列表
+ *
+ * 将名称写入提供的缓冲区数组，每个名称最多 32 字节。
+ *
+ * @param names  名称缓冲区数组（二维字符数组）
+ * @param count  数组容量（最大能存放多少个名称）
+ * @return 实际写入的中间件数量
+ */
+int cocoon_middleware_list(char names[][32], int count);
+
 /**
  * cocoon_middleware_init_builtin - 根据配置初始化内置中间件
  *

server.c

@@ -28,6 +28,7 @@
 #include "websocket.h"
 #include "platform.h"
 #include "middleware.h"
+#include <time.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -72,6 +73,10 @@ struct server_context {
 
 /* 全局活跃连接计数器（线程安全） */
 static atomic_int g_active_connections = 0;
+/* 服务器启动时间 */
+static time_t g_server_start_time = 0;
+/* 最大连接数（供健康检查端点使用） */
+static uint32_t g_max_connections = 0;
 
 /**
  * set_nonblocking - 设置 socket 为非阻塞模式
@@ -408,6 +413,83 @@ static bool handle_request(connection_t *conn, const char *root_dir) {
         return req.keep_alive;
     }
 
+    /* 健康检查端点 */
+    if (strcmp(req.path, "/_health") == 0) {
+        time_t now = time(NULL);
+        time_t uptime = now - g_server_start_time;
+        int active = atomic_load(&g_active_connections);
+
+        char mw_names[16][32];
+        int mw_count = cocoon_middleware_list(mw_names, 16);
+
+        /* 构建 JSON */
+        char body[2048];
+        int n = snprintf(body, sizeof(body),
+            "{\n"
+            "  \"status\": \"ok\",\n"
+            "  \"version\": \"Cocoon/1.0\",\n"
+            "  \"uptime_seconds\": %ld,\n"
+            "  \"connections\": {\n"
+            "    \"active\": %d,\n"
+            "    \"max\": %u\n"
+            "  },\n"
+            "  \"plugins\": {\n"
+            "    \"count\": %zu,\n"
+            "    \"list\": [\n",
+            uptime, active,
+            g_max_connections,
+            cocoon_plugin_count());
+
+        for (size_t i = 0; i < cocoon_plugin_count(); i++) {
+            const char *path = cocoon_plugin_get_path(i);
+            const char *ver = cocoon_plugin_get_version(i);
+            n += snprintf(body + n, sizeof(body) - n,
+                "      {\"path\":\"%s\",\"version\":\"%s\"}%s\n",
+                path ? path : "",
+                ver ? ver : "unknown",
+                (i + 1 < cocoon_plugin_count()) ? "," : "");
+        }
+
+        n += snprintf(body + n, sizeof(body) - n,
+            "    ]\n"
+            "  },\n"
+            "  \"middleware\": {\n"
+            "    \"count\": %d,\n"
+            "    \"names\": [\n",
+            mw_count);
+
+        for (int i = 0; i < mw_count; i++) {
+            n += snprintf(body + n, sizeof(body) - n,
+                "      \"%s\"%s\n",
+                mw_names[i],
+                (i + 1 < mw_count) ? "," : "");
+        }
+
+        n += snprintf(body + n, sizeof(body) - n,
+            "    ]\n"
+            "  }\n"
+            "}");
+
+        char header[512];
+        int header_len = snprintf(header, sizeof(header),
+            "HTTP/1.1 200 OK\r\n"
+            "Content-Type: application/json\r\n"
+            "Content-Length: %d\r\n"
+            "Connection: %s\r\n"
+            "Server: Cocoon/1.0\r\n"
+            "\r\n",
+            n, req.keep_alive ? "keep-alive" : "close");
+
+        send_all(conn->fd, header, (size_t)header_len);
+        send_all(conn->fd, body, (size_t)n);
+
+        conn->response_status = 200;
+        access_log_write((struct sockaddr *)&conn->client_addr, conn->addr_len,
+                         &req, conn->response_status, n);
+        http_request_free(&req);
+        return req.keep_alive;
+    }
+
     /* 安全路径拼接 */
     char real_path[4096];
     char root_normalized[4096];
@@ -1001,6 +1083,8 @@ server_context_t *server_create(const cocoon_config_t *config) {
     ctx->config.root_dir = strdup(config->root_dir);
     ctx->running = 1;
 
+    g_max_connections = config->max_connections;
+
     /* 创建监听 socket */
     ctx->listen_fd = socket(AF_INET, SOCK_STREAM, 0);
     if (ctx->listen_fd == COCOON_INVALID_SOCKET) {
@@ -1070,6 +1154,8 @@ server_context_t *server_create(const cocoon_config_t *config) {
 int server_start(server_context_t *ctx) {
     if (!ctx) return COCOON_ERROR;
 
+    g_server_start_time = time(NULL);
+
     if (ctx->config.threaded) {
         /* 多线程协程模式 */
         uint32_t num_workers = ctx->config.num_workers;

tests/integration_test.sh

@@ -409,7 +409,48 @@ assert_access_log() {
 start_server
 
 echo ""
-echo "=== 基础功能测试 ==="
+echo "=== 健康检查端点测试 ==="
+health_body=$(curl -s "$BASE/_health")
+health_status=$(curl -s -o /dev/null -w "%{http_code}" "$BASE/_health")
+if [[ "$health_status" == "200" ]]; then
+    echo "  ✓ /_health 状态码 — HTTP 200"
+    pass
+else
+    echo "  ✗ /_health 状态码 — 期望 200, 实际 $health_status"
+    fail
+fi
+if echo "$health_body" | grep -q '"status": "ok"'; then
+    echo "  ✓ /_health 响应体 — 包含 status: ok"
+    pass
+else
+    echo "  ✗ /_health 响应体 — 缺少 status: ok"
+    fail
+fi
+if echo "$health_body" | grep -q '"version": "Cocoon/1.0"'; then
+    echo "  ✓ /_health 响应体 — 包含版本信息"
+    pass
+else
+    echo "  ✗ /_health 响应体 — 缺少版本信息"
+    fail
+fi
+if echo "$health_body" | grep -q '"connections"'; then
+    echo "  ✓ /_health 响应体 — 包含连接数信息"
+    pass
+else
+    echo "  ✗ /_health 响应体 — 缺少连接数信息"
+    fail
+fi
+if echo "$health_body" | grep -q '"middleware"'; then
+    echo "  ✓ /_health 响应体 — 包含中间件信息"
+    pass
+else
+    echo "  ✗ /_health 响应体 — 缺少中间件信息"
+    fail
+fi
+
+assert_head_status "$BASE/_health" "200" "健康检查 HEAD"
+
+assert_status "$BASE/_health/nonexistent" "404" "健康检查路径遍历"
 assert_status "$BASE/" "200" "首页 GET"
 assert_status "$BASE/index.html" "200" "index.html GET"
 assert_status "$BASE/nonexist.html" "404" "404 页面"