feat: prove the Wi-Fi, LittleFS, and HTTP vertical slice

.gitignore

@@ -2,3 +2,4 @@
 sdkconfig.esp32-c6-devkitm-1
 .pio
 .vscode
+include/wifi_config.h

CMakeLists.txt

@@ -1,3 +1,9 @@
 cmake_minimum_required(VERSION 3.16.0)
 include($ENV{IDF_PATH}/tools/cmake/project.cmake)
+
+# PlatformIO installs the pinned ESP-IDF LittleFS component per environment.
+get_filename_component(platformio_environment "${CMAKE_BINARY_DIR}" NAME)
+list(APPEND EXTRA_COMPONENT_DIRS
+     "${CMAKE_SOURCE_DIR}/.pio/libdeps/${platformio_environment}/esp_littlefs")
+
 project(battleship)

PLANS.md

@@ -167,7 +167,7 @@ Execution record
 
 ## Milestone 002 — Prove the Wi-Fi, LittleFS, and HTTP vertical slice
 
-**Status:** `READY`  
+**Status:** `DONE`
 **Depends on:** Milestone 001
 
 ### Objective
@@ -203,11 +203,22 @@ Prove the MVP's basic delivery path: home Wi-Fi, LittleFS, and HTTP served direc
 
 If all criteria pass, set this milestone to `DONE`, append its execution record, and change Milestone 003 from `BLOCKED` to `READY`.
 
+### Execution record
+
+- Date: 2026-08-27
+- Board model and revision: ESP32-C6FH4 QFN32, revision v0.2; carrier board remains an unidentified SuperMini-style ESP32-C6 Mini.
+- Toolchain and library versions: PlatformIO Core 6.1.19; `espressif32` 7.0.1; ESP-IDF 6.0.1; pinned `esp_littlefs` 1.20.4 (commit `92ac3c2`).
+- Result: PASS
+- Evidence: Implemented the station-mode Wi-Fi state machine with bounded 2–32 second reconnect backoff, LittleFS mount without auto-formatting, static routes (`/`, `/styles.css`, `/app.js`), and `GET /api/health`. Static files are streamed in 1,024-byte chunks, have explicit MIME/cache headers, and select a matching precompressed `.gz` file when supplied by the LittleFS image. `data/` contains the local Russian diagnostic page, CSS, and JavaScript; `include/wifi_config.h.example` documents the ignored local credential file. `pio run -e esp32-c6-devkitm-1 -t buildfs` successfully created `littlefs.bin` containing all three assets. Firmware and LittleFS were uploaded to the ESP32-C6FH4, and esptool verified every written hash. A serial reset/read confirmed LittleFS mount, HTTP server startup on port 80, Wi-Fi association, and DHCP assignment without a restart. Five consecutive LAN `GET /api/health` requests returned HTTP 200; `GET /styles.css` returned `Content-Type: text/css; charset=utf-8` and `Cache-Control: public, max-age=86400`.
+- Measurements: Final credential-configured firmware build used 37,164 / 327,680 bytes of RAM (11.3%) and 987,644 / 2,097,152 bytes of flash (47.1%). The LittleFS partition is 1,984 KB; the mounted image reported 2,031,616 total bytes and 20,480 used bytes. The health endpoint reported RSSI from -43 to -46 dBm, 324,488 current free heap bytes, and 316,580 minimum free heap bytes after approximately 64 seconds. No new compiler warnings were emitted by the successful builds.
+- Issues or deviations: The first device upload exposed an `Invalid mbox` assertion because the HTTP server started before `esp_netif_init`; this was corrected before the final verified upload. `pio test -e esp32-c6-devkitm-1 --without-uploading` ran but errored because `test/` contains no test suite. On 2026-08-28, the user confirmed completion of the remaining two-device, Wi-Fi interruption/reconnect, gzip-delivery, and LittleFS mount-failure checks; their physical observations are accepted as the required evidence.
+- Next action: Milestone 003 is in progress. Do not begin Milestone 004 as part of this task.
+
 ---
 
 ## Milestone 003 — Prove real-time transport, fallback, and state isolation
 
-**Status:** `BLOCKED`  
+**Status:** `IN PROGRESS`  
 **Depends on:** Milestone 002
 
 ### Objective

data/app.js

@@ -0,0 +1,32 @@
+(() => {
+  const target = document.querySelector('#health');
+  const labels = {
+    uptime_ms: 'Время работы (мс)', wifi_state: 'Wi-Fi', rssi_dbm: 'RSSI (дБм)',
+    free_heap_bytes: 'Свободная память (байт)', min_free_heap_bytes: 'Мин. свободная память (байт)',
+    build_version: 'Версия сборки'
+  };
+
+  function render(health) {
+    target.replaceChildren();
+    for (const [key, label] of Object.entries(labels)) {
+      const term = document.createElement('dt');
+      const value = document.createElement('dd');
+      term.textContent = label;
+      value.textContent = health[key] ?? 'недоступно';
+      target.append(term, value);
+    }
+  }
+
+  async function refresh() {
+    try {
+      const response = await fetch('/api/health', { cache: 'no-store' });
+      if (!response.ok) throw new Error(`HTTP ${response.status}`);
+      render(await response.json());
+    } catch (error) {
+      target.textContent = `Не удалось получить состояние: ${error.message}`;
+    }
+  }
+
+  refresh();
+  window.setInterval(refresh, 5000);
+})();

data/index.html

@@ -0,0 +1,20 @@
+<!doctype html>
+<html lang="ru">
+  <head>
+    <meta charset="utf-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1">
+    <title>Морской бой — ESP32</title>
+    <link rel="stylesheet" href="/styles.css">
+  </head>
+  <body>
+    <main>
+      <h1>Морской бой</h1>
+      <p>ESP32-C6: проверка Wi-Fi, LittleFS и HTTP.</p>
+      <section aria-live="polite">
+        <h2>Состояние устройства</h2>
+        <dl id="health">Загрузка…</dl>
+      </section>
+    </main>
+    <script src="/app.js" defer></script>
+  </body>
+</html>

data/styles.css

@@ -0,0 +1,7 @@
+:root { color-scheme: dark; font-family: system-ui, sans-serif; }
+body { margin: 0; background: #10223a; color: #f4f7fb; }
+main { max-width: 42rem; margin: 0 auto; padding: 1.5rem; }
+section { background: #19395c; border-radius: .75rem; padding: 1rem; }
+dl { display: grid; grid-template-columns: max-content 1fr; gap: .5rem 1rem; }
+dt { font-weight: 700; }
+dd { margin: 0; overflow-wrap: anywhere; }

include/wifi_config.h.example

@@ -0,0 +1,6 @@
+#pragma once
+
+// Copy this file to include/wifi_config.h and set the local home-network
+// credentials. The copied file is ignored by Git and must never be committed.
+#define WIFI_CONFIG_SSID "replace-with-network-name"
+#define WIFI_CONFIG_PASSWORD "replace-with-network-password"

platformio.ini

@@ -13,5 +13,7 @@ platform = espressif32 @ 7.0.1
 board = esp32-c6-devkitm-1
 framework = espidf
 board_build.partitions = partitions.csv
+board_build.filesystem = littlefs
+lib_deps = https://github.com/joltwallet/esp_littlefs.git#v1.20.4
 monitor_port = /dev/ttyACM0
 monitor_speed = 115200

src/CMakeLists.txt

@@ -1,6 +1,8 @@
 # This file was automatically generated for projects
 # without default 'CMakeLists.txt' file.
 
-FILE(GLOB_RECURSE app_sources ${CMAKE_SOURCE_DIR}/src/*.*)
+idf_component_register(
-
+  SRCS "main.c"
-idf_component_register(SRCS ${app_sources})
+  INCLUDE_DIRS "../include"
+  REQUIRES esp_event esp_http_server esp_netif esp_wifi esp_littlefs nvs_flash
+)

src/main.c

@@ -1,141 +1,346 @@
 #include <inttypes.h>
-#include <stddef.h>
+#include <stdbool.h>
 #include <stdint.h>
+#include <stdio.h>
+#include <string.h>
 
-#include "driver/gpio.h"
+#include "esp_check.h"
-#include "esp_chip_info.h"
+#include "esp_event.h"
-#include "esp_err.h"
+#include "esp_http_server.h"
-#include "esp_flash.h"
+#include "esp_littlefs.h"
 #include "esp_log.h"
-#include "esp_system.h"
+#include "esp_netif.h"
 #include "esp_timer.h"
+#include "esp_wifi.h"
 #include "freertos/FreeRTOS.h"
-#include "freertos/task.h"
+#include "freertos/portmacro.h"
+#include "nvs_flash.h"
 
-static const char *const kLogTag = "bringup";
+#if __has_include("wifi_config.h")
-static const gpio_num_t kCandidateLedGpio = GPIO_NUM_8;
+#include "wifi_config.h"
-static const uint32_t kLedProbeCount = 10;
+#define WIFI_CONFIG_AVAILABLE 1
-static const uint32_t kLedProbeIntervalMs = 500;
+#else
-static const uint32_t kHealthIntervalMs = 30000;
+#define WIFI_CONFIG_AVAILABLE 0
-static const uint32_t kStartupAttachmentDelayMs = 10000;
+#endif
 
-static const char *reset_reason_name(esp_reset_reason_t reason) {
+static const char *const kLogTag = "vertical_slice";
-  switch (reason) {
+static const char *const kBuildVersion = "m002";
-    case ESP_RST_UNKNOWN:
+static const char *const kLittlefsBasePath = "/littlefs";
-      return "unknown";
+static const char *const kLittlefsPartitionLabel = "littlefs";
-    case ESP_RST_POWERON:
+static const size_t kFileChunkBytes = 1024;
-      return "power_on";
+
-    case ESP_RST_EXT:
+typedef struct {
-      return "external";
+  bool configured;
-    case ESP_RST_SW:
+  bool connected;
-      return "software";
+  bool retry_scheduled;
-    case ESP_RST_PANIC:
+  uint8_t reconnect_attempt;
-      return "panic";
+  char ip_address[16];
-    case ESP_RST_INT_WDT:
+} wifi_state_t;
-      return "interrupt_watchdog";
+
-    case ESP_RST_TASK_WDT:
+static portMUX_TYPE s_wifi_lock = portMUX_INITIALIZER_UNLOCKED;
-      return "task_watchdog";
+static wifi_state_t s_wifi_state = {0};
-    case ESP_RST_WDT:
+static bool s_littlefs_mounted;
-      return "other_watchdog";
+
-    case ESP_RST_DEEPSLEEP:
+static wifi_state_t wifi_state_snapshot(void) {
-      return "deep_sleep";
+  wifi_state_t snapshot;
-    case ESP_RST_BROWNOUT:
+  portENTER_CRITICAL(&s_wifi_lock);
-      return "brownout";
+  snapshot = s_wifi_state;
-    case ESP_RST_SDIO:
+  portEXIT_CRITICAL(&s_wifi_lock);
-      return "sdio";
+  return snapshot;
-    case ESP_RST_USB:
-      return "usb";
-    case ESP_RST_JTAG:
-      return "jtag";
-    case ESP_RST_EFUSE:
-      return "efuse";
-    case ESP_RST_PWR_GLITCH:
-      return "power_glitch";
-    case ESP_RST_CPU_LOCKUP:
-      return "cpu_lockup";
 }
 
-  return "unrecognized";
+#if WIFI_CONFIG_AVAILABLE
-}
+static const uint8_t kMaxReconnectExponent = 5;
+static esp_timer_handle_t s_reconnect_timer;
 
-static void log_heap(uint64_t uptime_ms) {
+static void reconnect_timer_callback(void *unused) {
-  const size_t free_heap_bytes = esp_get_free_heap_size();
+  (void)unused;
-  const size_t minimum_free_heap_bytes = esp_get_minimum_free_heap_size();
+  portENTER_CRITICAL(&s_wifi_lock);
-  uint32_t flash_size_bytes = 0;
+  s_wifi_state.retry_scheduled = false;
-  const esp_err_t flash_result = esp_flash_get_size(NULL, &flash_size_bytes);
+  portEXIT_CRITICAL(&s_wifi_lock);
 
-  if (flash_result == ESP_OK) {
+  const esp_err_t result = esp_wifi_connect();
-    ESP_LOGI(kLogTag,
-             "health uptime_ms=%" PRIu64 " reset_reason=%s flash_bytes=%" PRIu32
-             " free_heap_bytes=%u min_free_heap_bytes=%u",
-             uptime_ms,
-             reset_reason_name(esp_reset_reason()),
-             flash_size_bytes,
-             (unsigned int)free_heap_bytes,
-             (unsigned int)minimum_free_heap_bytes);
-  } else {
-    ESP_LOGE(kLogTag, "health flash_size_failed=%s", esp_err_to_name(flash_result));
-  }
-}
-
-static void probe_candidate_led(void) {
-  ESP_LOGI(kLogTag,
-           "led_probe gpio=%d transitions=%" PRIu32 " interval_ms=%" PRIu32 "; visually confirm the LED",
-           (int)kCandidateLedGpio,
-           kLedProbeCount,
-           kLedProbeIntervalMs);
-
-  esp_err_t result = gpio_reset_pin(kCandidateLedGpio);
   if (result != ESP_OK) {
-    ESP_LOGW(kLogTag, "led_probe gpio_reset_pin failed: %s", esp_err_to_name(result));
+    ESP_LOGW(kLogTag, "wifi connect request failed: %s", esp_err_to_name(result));
+  }
+}
+
+static void schedule_reconnect(uint32_t delay_ms) {
+  bool should_start_timer = false;
+  portENTER_CRITICAL(&s_wifi_lock);
+  if (s_wifi_state.configured && !s_wifi_state.connected && !s_wifi_state.retry_scheduled) {
+    s_wifi_state.retry_scheduled = true;
+    should_start_timer = true;
+  }
+  portEXIT_CRITICAL(&s_wifi_lock);
+
+  if (!should_start_timer) {
     return;
   }
-
+  const esp_err_t result = esp_timer_start_once(s_reconnect_timer, (uint64_t)delay_ms * 1000U);
-  result = gpio_set_direction(kCandidateLedGpio, GPIO_MODE_OUTPUT);
   if (result != ESP_OK) {
-    ESP_LOGW(kLogTag, "led_probe gpio_set_direction failed: %s", esp_err_to_name(result));
+    portENTER_CRITICAL(&s_wifi_lock);
+    s_wifi_state.retry_scheduled = false;
+    portEXIT_CRITICAL(&s_wifi_lock);
+    ESP_LOGW(kLogTag, "wifi reconnect timer failed: %s", esp_err_to_name(result));
+  }
+}
+
+static uint32_t next_reconnect_delay_ms(void) {
+  uint8_t exponent;
+  portENTER_CRITICAL(&s_wifi_lock);
+  if (s_wifi_state.reconnect_attempt < kMaxReconnectExponent) {
+    ++s_wifi_state.reconnect_attempt;
+  }
+  exponent = s_wifi_state.reconnect_attempt;
+  portEXIT_CRITICAL(&s_wifi_lock);
+  return 1000U << exponent;
+}
+
+static void wifi_event_handler(void *argument,
+                               esp_event_base_t event_base,
+                               int32_t event_id,
+                               void *event_data) {
+  (void)argument;
+  if (event_base == WIFI_EVENT && event_id == WIFI_EVENT_STA_START) {
+    ESP_LOGI(kLogTag, "wifi station started");
+    schedule_reconnect(0);
     return;
   }
+  if (event_base == WIFI_EVENT && event_id == WIFI_EVENT_STA_DISCONNECTED) {
+    const uint32_t delay_ms = next_reconnect_delay_ms();
+    portENTER_CRITICAL(&s_wifi_lock);
+    s_wifi_state.connected = false;
+    s_wifi_state.ip_address[0] = '\0';
+    portEXIT_CRITICAL(&s_wifi_lock);
+    ESP_LOGW(kLogTag, "wifi disconnected; reconnecting in %" PRIu32 " ms", delay_ms);
+    schedule_reconnect(delay_ms);
+    return;
+  }
+  if (event_base == IP_EVENT && event_id == IP_EVENT_STA_GOT_IP) {
+    const ip_event_got_ip_t *const event = (const ip_event_got_ip_t *)event_data;
+    char address[16];
+    esp_ip4addr_ntoa(&event->ip_info.ip, address, sizeof(address));
+    portENTER_CRITICAL(&s_wifi_lock);
+    s_wifi_state.connected = true;
+    s_wifi_state.reconnect_attempt = 0;
+    snprintf(s_wifi_state.ip_address, sizeof(s_wifi_state.ip_address), "%s", address);
+    portEXIT_CRITICAL(&s_wifi_lock);
+    ESP_LOGI(kLogTag, "wifi connected ip=%s", address);
+  }
+}
+#endif
 
-  for (uint32_t transition = 0; transition < kLedProbeCount; ++transition) {
+static esp_err_t start_wifi(void) {
-    gpio_set_level(kCandidateLedGpio, transition % 2U);
+#if !WIFI_CONFIG_AVAILABLE
-    vTaskDelay(pdMS_TO_TICKS(kLedProbeIntervalMs));
+  ESP_LOGE(kLogTag,
+           "wifi is not configured; copy include/wifi_config.h.example to include/wifi_config.h");
+  return ESP_ERR_INVALID_STATE;
+#else
+  wifi_init_config_t init_config = WIFI_INIT_CONFIG_DEFAULT();
+  wifi_config_t station_config = {0};
+  esp_timer_create_args_t reconnect_timer_args = {
+      .callback = reconnect_timer_callback,
+      .name = "wifi_reconnect",
+  };
+
+  portENTER_CRITICAL(&s_wifi_lock);
+  s_wifi_state.configured = true;
+  portEXIT_CRITICAL(&s_wifi_lock);
+  esp_netif_create_default_wifi_sta();
+  ESP_RETURN_ON_ERROR(esp_wifi_init(&init_config), kLogTag, "wifi initialization failed");
+  ESP_RETURN_ON_ERROR(esp_event_handler_instance_register(
+                          WIFI_EVENT, ESP_EVENT_ANY_ID, wifi_event_handler, NULL, NULL),
+                      kLogTag,
+                      "wifi event registration failed");
+  ESP_RETURN_ON_ERROR(esp_event_handler_instance_register(
+                          IP_EVENT, IP_EVENT_STA_GOT_IP, wifi_event_handler, NULL, NULL),
+                      kLogTag,
+                      "ip event registration failed");
+  ESP_RETURN_ON_ERROR(esp_timer_create(&reconnect_timer_args, &s_reconnect_timer),
+                      kLogTag,
+                      "wifi reconnect timer creation failed");
+
+  snprintf((char *)station_config.sta.ssid, sizeof(station_config.sta.ssid), "%s", WIFI_CONFIG_SSID);
+  snprintf((char *)station_config.sta.password,
+           sizeof(station_config.sta.password),
+           "%s",
+           WIFI_CONFIG_PASSWORD);
+  station_config.sta.threshold.authmode = WIFI_AUTH_WPA2_PSK;
+  station_config.sta.pmf_cfg.capable = true;
+  station_config.sta.pmf_cfg.required = false;
+  ESP_RETURN_ON_ERROR(esp_wifi_set_mode(WIFI_MODE_STA), kLogTag, "wifi mode setup failed");
+  ESP_RETURN_ON_ERROR(esp_wifi_set_config(WIFI_IF_STA, &station_config), kLogTag, "wifi configuration failed");
+  return esp_wifi_start();
+#endif
 }
 
-  gpio_set_level(kCandidateLedGpio, 0);
+static const char *wifi_state_name(const wifi_state_t *state) {
-  ESP_LOGI(kLogTag, "led_probe complete; USB serial remained available during probe");
+  if (!state->configured) {
+    return "not_configured";
+  }
+  return state->connected ? "connected" : "connecting";
 }
 
-static void log_startup(void) {
+static esp_err_t health_handler(httpd_req_t *request) {
-  esp_chip_info_t chip_info = {0};
+  const wifi_state_t wifi_state = wifi_state_snapshot();
-  uint32_t flash_size_bytes = 0;
+  int8_t rssi_dbm = 0;
-  const esp_err_t flash_result = esp_flash_get_size(NULL, &flash_size_bytes);
+  wifi_ap_record_t access_point = {0};
-
+  if (wifi_state.connected && esp_wifi_sta_get_ap_info(&access_point) == ESP_OK) {
-  esp_chip_info(&chip_info);
+    rssi_dbm = access_point.rssi;
-  ESP_LOGI(kLogTag,
+  }
-           "startup reset_reason=%s chip_model=%d chip_revision=%d cores=%d features=0x%08" PRIx32,
+  char response[320];
-           reset_reason_name(esp_reset_reason()),
+  const int written = snprintf(response,
-           (int)chip_info.model,
+                               sizeof(response),
-           chip_info.revision,
+                               "{\"uptime_ms\":%" PRIu64
-           chip_info.cores,
+                               ",\"wifi_state\":\"%s\",\"rssi_dbm\":%d"
-           chip_info.features);
+                               ",\"free_heap_bytes\":%u,\"min_free_heap_bytes\":%u"
-
+                               ",\"build_version\":\"%s\"}",
-  if (flash_result == ESP_OK) {
+                               (uint64_t)(esp_timer_get_time() / 1000),
-    ESP_LOGI(kLogTag, "startup flash_bytes=%" PRIu32, flash_size_bytes);
+                               wifi_state_name(&wifi_state),
-  } else {
+                               (int)rssi_dbm,
-    ESP_LOGE(kLogTag, "startup flash_size_failed=%s", esp_err_to_name(flash_result));
+                               (unsigned int)esp_get_free_heap_size(),
+                               (unsigned int)esp_get_minimum_free_heap_size(),
+                               kBuildVersion);
+  if (written < 0 || (size_t)written >= sizeof(response)) {
+    return httpd_resp_send_err(request, HTTPD_500_INTERNAL_SERVER_ERROR, "health response failed");
+  }
+  httpd_resp_set_type(request, "application/json");
+  httpd_resp_set_hdr(request, "Cache-Control", "no-store");
+  return httpd_resp_send(request, response, HTTPD_RESP_USE_STRLEN);
 }
 
-  log_heap(0);
+static const char *mime_type_for_path(const char *path) {
+  if (strcmp(path, "/index.html") == 0) {
+    return "text/html; charset=utf-8";
+  }
+  if (strcmp(path, "/styles.css") == 0) {
+    return "text/css; charset=utf-8";
+  }
+  return "application/javascript; charset=utf-8";
+}
+
+static bool request_accepts_gzip(httpd_req_t *request) {
+  const size_t header_length = httpd_req_get_hdr_value_len(request, "Accept-Encoding");
+  if (header_length == 0 || header_length >= 96) {
+    return false;
+  }
+  char header[96];
+  return httpd_req_get_hdr_value_str(request, "Accept-Encoding", header, sizeof(header)) == ESP_OK &&
+         strstr(header, "gzip") != NULL;
+}
+
+static esp_err_t send_static_file(httpd_req_t *request, const char *asset_path) {
+  char filesystem_path[80];
+  char gzip_path[84];
+  bool gzip = false;
+  const char *path_to_open = filesystem_path;
+  snprintf(filesystem_path, sizeof(filesystem_path), "%s%s", kLittlefsBasePath, asset_path);
+  if (request_accepts_gzip(request)) {
+    snprintf(gzip_path, sizeof(gzip_path), "%s.gz", filesystem_path);
+    FILE *const compressed = fopen(gzip_path, "rb");
+    if (compressed != NULL) {
+      fclose(compressed);
+      path_to_open = gzip_path;
+      gzip = true;
+    }
+  }
+  FILE *const file = fopen(path_to_open, "rb");
+  if (file == NULL) {
+    return httpd_resp_send_err(request, HTTPD_404_NOT_FOUND, "static asset not found");
+  }
+  httpd_resp_set_type(request, mime_type_for_path(asset_path));
+  httpd_resp_set_hdr(request,
+                     "Cache-Control",
+                     strcmp(asset_path, "/index.html") == 0 ? "no-cache" : "public, max-age=86400");
+  if (gzip) {
+    httpd_resp_set_hdr(request, "Content-Encoding", "gzip");
+    httpd_resp_set_hdr(request, "Vary", "Accept-Encoding");
+  }
+
+  char chunk[kFileChunkBytes];
+  size_t bytes_read;
+  esp_err_t result = ESP_OK;
+  while ((bytes_read = fread(chunk, 1, sizeof(chunk), file)) > 0) {
+    result = httpd_resp_send_chunk(request, chunk, bytes_read);
+    if (result != ESP_OK) {
+      break;
+    }
+  }
+  fclose(file);
+  return result == ESP_OK ? httpd_resp_send_chunk(request, NULL, 0) : result;
+}
+
+static esp_err_t root_handler(httpd_req_t *request) {
+  if (!s_littlefs_mounted) {
+    httpd_resp_set_status(request, "503 Service Unavailable");
+    return httpd_resp_send(request, "LittleFS is unavailable", HTTPD_RESP_USE_STRLEN);
+  }
+  return send_static_file(request, "/index.html");
+}
+
+static esp_err_t static_file_handler(httpd_req_t *request) {
+  if (!s_littlefs_mounted) {
+    httpd_resp_set_status(request, "503 Service Unavailable");
+    return httpd_resp_send(request, "LittleFS is unavailable", HTTPD_RESP_USE_STRLEN);
+  }
+  if (strcmp(request->uri, "/styles.css") != 0 && strcmp(request->uri, "/app.js") != 0) {
+    return httpd_resp_send_err(request, HTTPD_404_NOT_FOUND, "asset not found");
+  }
+  return send_static_file(request, request->uri);
+}
+
+static esp_err_t start_http_server(void) {
+  httpd_handle_t server = NULL;
+  httpd_config_t config = HTTPD_DEFAULT_CONFIG();
+  config.max_uri_handlers = 3;
+  config.uri_match_fn = httpd_uri_match_wildcard;
+  config.lru_purge_enable = true;
+  ESP_RETURN_ON_ERROR(httpd_start(&server, &config), kLogTag, "http server start failed");
+  const httpd_uri_t root = {.uri = "/", .method = HTTP_GET, .handler = root_handler};
+  const httpd_uri_t health = {.uri = "/api/health", .method = HTTP_GET, .handler = health_handler};
+  const httpd_uri_t static_files = {.uri = "/*", .method = HTTP_GET, .handler = static_file_handler};
+  ESP_RETURN_ON_ERROR(httpd_register_uri_handler(server, &root), kLogTag, "root route registration failed");
+  ESP_RETURN_ON_ERROR(httpd_register_uri_handler(server, &health), kLogTag, "health route registration failed");
+  ESP_RETURN_ON_ERROR(httpd_register_uri_handler(server, &static_files), kLogTag, "static route registration failed");
+  ESP_LOGI(kLogTag, "http server started on port %d", config.server_port);
+  return ESP_OK;
+}
+
+static void mount_littlefs(void) {
+  const esp_vfs_littlefs_conf_t config = {
+      .base_path = kLittlefsBasePath,
+      .partition_label = kLittlefsPartitionLabel,
+      .format_if_mount_failed = false,
+      .dont_mount = false,
+      .grow_on_mount = false,
+  };
+  const esp_err_t result = esp_vfs_littlefs_register(&config);
+  if (result != ESP_OK) {
+    ESP_LOGE(kLogTag, "littlefs mount failed: %s; HTTP static assets remain unavailable", esp_err_to_name(result));
+    return;
+  }
+  size_t total_bytes = 0;
+  size_t used_bytes = 0;
+  if (esp_littlefs_info(kLittlefsPartitionLabel, &total_bytes, &used_bytes) == ESP_OK) {
+    ESP_LOGI(kLogTag, "littlefs mounted total_bytes=%u used_bytes=%u", (unsigned int)total_bytes, (unsigned int)used_bytes);
+  }
+  s_littlefs_mounted = true;
 }
 
 void app_main(void) {
-  vTaskDelay(pdMS_TO_TICKS(kStartupAttachmentDelayMs));
+  esp_err_t result = nvs_flash_init();
-  log_startup();
+  if (result == ESP_ERR_NVS_NO_FREE_PAGES || result == ESP_ERR_NVS_NEW_VERSION_FOUND) {
-  probe_candidate_led();
+    ESP_ERROR_CHECK(nvs_flash_erase());
-
+    result = nvs_flash_init();
-  while (true) {
+  }
-    log_heap((uint64_t)(esp_timer_get_time() / 1000));
+  ESP_ERROR_CHECK(result);
-    vTaskDelay(pdMS_TO_TICKS(kHealthIntervalMs));
+  ESP_ERROR_CHECK(esp_netif_init());
+  ESP_ERROR_CHECK(esp_event_loop_create_default());
+  mount_littlefs();
+  ESP_ERROR_CHECK(start_http_server());
+  result = start_wifi();
+  if (result != ESP_OK) {
+    ESP_LOGW(kLogTag, "wifi unavailable: %s", esp_err_to_name(result));
   }
 }