fix: divide-by-zero crash when no WiFi networks configured

- Guard tollgate_config_get_next_wifi against network_count=0
- Add fallback parsing for wifi_ssid/wifi_password flat fields
- Add heap info to API server failure log for debugging
- All 75 unit tests passing

3 files changed, 15 insertions, 1 deletions

diff --git a/main/config.c b/main/config.c
index 45eb8ff..54642a2 100644
--- a/main/config.c
+++ b/main/config.c
@@ -126,6 +126,16 @@ esp_err_t tollgate_config_init(void)
         }
     }
 
+    if (g_config.network_count == 0) {
+        cJSON *ssid = cJSON_GetObjectItem(root, "wifi_ssid");
+        cJSON *pass = cJSON_GetObjectItem(root, "wifi_password");
+        if (ssid && cJSON_IsString(ssid) && pass && cJSON_IsString(pass)) {
+            strncpy(g_config.networks[0].ssid, ssid->valuestring, sizeof(g_config.networks[0].ssid) - 1);
+            strncpy(g_config.networks[0].password, pass->valuestring, sizeof(g_config.networks[0].password) - 1);
+            g_config.network_count = 1;
+        }
+    }
+
     cJSON *ap_pass = cJSON_GetObjectItem(root, "ap_password");
     if (ap_pass) strncpy(g_config.ap_password, ap_pass->valuestring, sizeof(g_config.ap_password) - 1);
 
@@ -315,6 +325,7 @@ esp_err_t tollgate_config_get_wifi(wifi_config_t *wifi_config)
 
 esp_err_t tollgate_config_get_next_wifi(wifi_config_t *wifi_config)
 {
+    if (g_config.network_count == 0) return ESP_ERR_NOT_FOUND;
     g_config.current_network = (g_config.current_network + 1) % g_config.network_count;
     return tollgate_config_get_wifi(wifi_config);
 }
diff --git a/main/tollgate_api.c b/main/tollgate_api.c
index 22b30ee..997dd09 100644
--- a/main/tollgate_api.c
+++ b/main/tollgate_api.c
@@ -6,6 +6,7 @@
 #include "nucula_wallet.h"
 #include "mint_health.h"
 #include "esp_log.h"
+#include "esp_system.h"
 #include "cJSON.h"
 #include "lwip/sockets.h"
 #include "lwip/netdb.h"
@@ -524,7 +525,8 @@ esp_err_t tollgate_api_start(void)
 
     esp_err_t ret = httpd_start(&s_api_server, &config);
     if (ret != ESP_OK) {
-        ESP_LOGE(TAG, "Failed to start API server: %s", esp_err_to_name(ret));
+        ESP_LOGE(TAG, "Failed to start API server: %s (heap: %lu)", esp_err_to_name(ret), (unsigned long)esp_get_free_heap_size());
+        s_api_server = NULL;
         return ret;
     }
 
diff --git a/main/tollgate_main.c b/main/tollgate_main.c
index 018d934..a39ccc9 100644
--- a/main/tollgate_main.c
+++ b/main/tollgate_main.c
@@ -5,6 +5,7 @@
 #include "esp_wifi.h"
 #include "esp_event.h"
 #include "esp_log.h"
+#include "esp_system.h"
 #include "nvs_flash.h"
 #include "esp_netif.h"
 #include "lwip/netif.h"