Sync display with live TollGate state

- Periodic refresh: wallet balance + client count every 5s from main loop
- display_notify_payment() API: passes payment amount and time allotment
- tollgate_api.c: triggers PAYMENT_RECEIVED state after wallet receive
- AP station events update client count in real-time
- Config data (price, mint) passed to display during boot phase
- Payment screen shows actual sats paid and time purchased
- Updated DISPLAY_UI_PLAN.md with state-sync audit and checklist

4 files changed, 36 insertions, 4 deletions

diff --git a/main/display.c b/main/display.c
index add97db..0935743 100644
--- a/main/display.c
+++ b/main/display.c
@@ -2,6 +2,7 @@
 #include "axs15231b.h"
 #include "qrcoded.h"
 #include "font.h"
+#include "nucula_wallet.h"
 #include "esp_log.h"
 #include "freertos/FreeRTOS.h"
 #include "freertos/task.h"
@@ -34,6 +35,8 @@ static int s_price_per_step = 0;
 static bool s_initialized = false;
 static int64_t s_last_qr_switch = 0;
 static display_qr_mode_t s_qr_mode = DISPLAY_QR_WIFI;
+static int s_last_payment_sats = 0;
+static int64_t s_last_allotment_ms = 0;
 
 static int qr_version_from_strlen(int len) {
     if (len <= 17) return 1;
@@ -251,13 +254,18 @@ static void render_payment_screen(void) {
 
     char line[48];
 
-    snprintf(line, sizeof(line), "Paid: %d sats", s_price_per_step);
+    snprintf(line, sizeof(line), "Paid: %d sats", s_last_payment_sats);
     int lw = strlen(line) * 8;
     display_render_text((screen_w - lw) / 2, 270, line, COLOR_WHITE, COLOR_BG, 1);
 
-    const char *time_msg = "Time: 1 min";
-    int tw = strlen(time_msg) * 8;
-    display_render_text((screen_w - tw) / 2, 290, time_msg, COLOR_WHITE, COLOR_BG, 1);
+    int64_t secs = s_last_allotment_ms / 1000;
+    if (secs >= 60) {
+        snprintf(line, sizeof(line), "Time: %lld min", (long long)(secs / 60));
+    } else {
+        snprintf(line, sizeof(line), "Time: %lld sec", (long long)secs);
+    }
+    lw = strlen(line) * 8;
+    display_render_text((screen_w - lw) / 2, 290, line, COLOR_WHITE, COLOR_BG, 1);
 
     snprintf(line, sizeof(line), "Wallet: %llu sats", (unsigned long long)s_wallet_balance);
     lw = strlen(line) * 8;
@@ -378,3 +386,10 @@ void display_update(const char *ap_ssid, int active_clients,
     s_active_clients = active_clients;
     s_wallet_balance = wallet_balance;
 }
+
+void display_notify_payment(int amount_sats, int64_t allotment_ms) {
+    s_last_payment_sats = amount_sats;
+    s_last_allotment_ms = allotment_ms;
+    s_wallet_balance = nucula_wallet_balance();
+    display_set_state(DISPLAY_PAYMENT_RECEIVED);
+}
diff --git a/main/display.h b/main/display.h
index 1530e57..49b3ffd 100644
--- a/main/display.h
+++ b/main/display.h
@@ -23,6 +23,7 @@ void display_update(const char *ap_ssid, int active_clients,
                     uint64_t wallet_balance, const char *portal_url,
                     const char *mint_url, int price_per_step,
                     const char *wifi_status);
+void display_notify_payment(int amount_sats, int64_t allotment_ms);
 void display_render_text(int x, int y, const char *text, uint16_t fg, uint16_t bg, int scale);
 void display_render_qr(const char *text);
 
diff --git a/main/tollgate_api.c b/main/tollgate_api.c
index 650b0f3..7ddfb9e 100644
--- a/main/tollgate_api.c
+++ b/main/tollgate_api.c
@@ -4,6 +4,7 @@
 #include "session.h"
 #include "firewall.h"
 #include "nucula_wallet.h"
+#include "display.h"
 #include "esp_log.h"
 #include "cJSON.h"
 #include "lwip/sockets.h"
@@ -313,6 +314,8 @@ static esp_err_t api_post_payment(httpd_req_t *req)
 
     nucula_wallet_receive(body_copy);
 
+    display_notify_payment(token->total_amount, allotment);
+
     free(states);
     free(token);
     return ESP_OK;
diff --git a/main/tollgate_main.c b/main/tollgate_main.c
index 7fd50ad..345295a 100644
--- a/main/tollgate_main.c
+++ b/main/tollgate_main.c
@@ -77,11 +77,13 @@ static void wifi_event_handler(void *arg, esp_event_base_t event_base,
         ESP_LOGI(TAG, "Station connected: MAC=%02x:%02x:%02x:%02x:%02x:%02x",
                  event->mac[0], event->mac[1], event->mac[2],
                  event->mac[3], event->mac[4], event->mac[5]);
+        display_update(NULL, session_active_count(), 0, NULL, NULL, 0, NULL);
     } else if (event_base == WIFI_EVENT && event_id == WIFI_EVENT_AP_STADISCONNECTED) {
         wifi_event_ap_stadisconnected_t *event = (wifi_event_ap_stadisconnected_t *)event_data;
         ESP_LOGI(TAG, "Station disconnected: MAC=%02x:%02x:%02x:%02x:%02x:%02x",
                  event->mac[0], event->mac[1], event->mac[2],
                  event->mac[3], event->mac[4], event->mac[5]);
+        display_update(NULL, session_active_count(), 0, NULL, NULL, 0, NULL);
     }
 }
 
@@ -314,6 +316,9 @@ void app_main(void)
 
     ESP_LOGI(TAG, "WiFi AP+STA started, waiting for connection...");
 
+    display_update(tcfg->ap_ssid, 0, 0, NULL,
+                   tcfg->mint_url, tcfg->price_per_step, "connecting...");
+
     if (tollgate_config_get_wifi(&(wifi_config_t){0}) != ESP_OK) {
         ESP_LOGI(TAG, "No STA network configured, starting services immediately");
         xTaskCreate(services_start_task, "svc_start", 32768, NULL, 5, NULL);
@@ -324,5 +329,13 @@ void app_main(void)
         session_tick();
         tollgate_client_tick();
         lightning_payout_tick();
+
+        static int display_tick = 0;
+        if (++display_tick >= 5) {
+            display_tick = 0;
+            display_update(NULL, session_active_count(),
+                           nucula_wallet_balance(), NULL,
+                           NULL, 0, NULL);
+        }
     }
 }