refactor(build): consolidate envs to production/debug/test; add compiler hardening flags

- Replace 11 per-frequency build environments with 3 role-based targets
  (production, debug, test) using shared [env] base section
- Move LoRa frequency and sender-ID config from build flags into config.h
  so all variants build from the same source
- Add -fstack-protector-strong, -D_FORTIFY_SOURCE=2, -Wformat-security
- Add Unity test framework to lib_deps for pio test support
- Add __pycache__/ to .gitignore

.gitignore

@@ -3,3 +3,5 @@
 .vscode/c_cpp_properties.json
 .vscode/launch.json
 .vscode/ipch
+
+__pycache__/

include/config.h

@@ -12,6 +12,25 @@ enum class BatchRetryPolicy : uint8_t {
   Drop = 1
 };
 
+// =============================================================================
+// ██  DEPLOYMENT SETTINGS  — adjust these for your hardware / frequency band
+// =============================================================================
+
+// LoRa frequency — uncomment ONE line:
+#define LORA_FREQUENCY_HZ 433E6    // 433 MHz (EU ISM, default)
+// #define LORA_FREQUENCY_HZ 868E6 // 868 MHz (EU SRD)
+// #define LORA_FREQUENCY_HZ 915E6 // 915 MHz (US ISM)
+
+// Expected sender device IDs (short-IDs).  The receiver will only accept
+// batches from these senders.  Add one entry per physical sender board.
+constexpr uint8_t NUM_SENDERS = 1;
+inline constexpr uint16_t EXPECTED_SENDER_IDS[NUM_SENDERS] = {
+  0xF19C   // TTGO #1 – 433 MHz sender
+  // 0x7EB4 // TTGO #2 – 868 MHz sender (uncomment & adjust NUM_SENDERS)
+};
+
+// =============================================================================
+
 // Pin definitions
 constexpr uint8_t PIN_LORA_SCK = 5;
 constexpr uint8_t PIN_LORA_MISO = 19;
@@ -34,10 +53,7 @@ constexpr uint8_t PIN_OLED_CTRL = 13;
 
 constexpr uint8_t PIN_METER_RX = 34;
 
-// LoRa settings
+// LoRa radio parameters
-#ifndef LORA_FREQUENCY_HZ
-#define LORA_FREQUENCY_HZ 433E6
-#endif
 constexpr long LORA_FREQUENCY = LORA_FREQUENCY_HZ;
 constexpr uint8_t LORA_SPREADING_FACTOR = 12;
 constexpr long LORA_BANDWIDTH = 125E3;
@@ -110,6 +126,8 @@ constexpr const char *AP_SSID_PREFIX = "DD3-Bridge-";
 constexpr const char *AP_PASSWORD = "changeme123";
 constexpr bool WEB_AUTH_REQUIRE_STA = true;
 constexpr bool WEB_AUTH_REQUIRE_AP = true;
+// SECURITY: these defaults are only used until the user sets credentials via
+// the web config page (/wifi).  The first-boot AP forces password change.
 constexpr const char *WEB_AUTH_DEFAULT_USER = "admin";
 constexpr const char *WEB_AUTH_DEFAULT_PASS = "admin";
 inline constexpr char HA_MANUFACTURER[] = "AcidBurns";
@@ -126,11 +144,6 @@ static_assert(
     HA_MANUFACTURER[9] == '\0',
     "HA_MANUFACTURER must remain exactly \"AcidBurns\"");
 
-constexpr uint8_t NUM_SENDERS = 1;
 constexpr uint32_t MIN_ACCEPTED_EPOCH_UTC = 1769904000UL; // 2026-02-01 00:00:00 UTC
-inline constexpr uint16_t EXPECTED_SENDER_IDS[NUM_SENDERS] = {
-  0xF19C //433mhz sender
-  //0x7EB4 //868mhz sender
-};
 
 DeviceRole detect_role();

platformio.ini

@@ -1,14 +1,14 @@
 ; PlatformIO Project Configuration File
 ;
-;   Build options: build flags, source filter
+; Build targets:
-;   Upload options: custom upload port, speed and extra flags
+;   production – serial off, light-sleep on (normal deployment)
-;   Library options: dependencies, extra library storages
+;   debug      – serial + meter diag + state tracing (real meter, real data)
-;   Advanced options: extra scripting
+;   test       – synthetic meter data + payload codec self-test (no real meter needed)
 ;
-; Please visit documentation for the other options and examples
+; LoRa frequency and sender IDs are configured in include/config.h,
-; https://docs.platformio.org/page/projectconf.html
+; NOT via build flags.  Change them there before building.
 
-[env:lilygo-t3-v1-6-1]
+[env]
 platform = https://github.com/pioarduino/platform-espressif32/releases/download/51.03.07/platform-espressif32.zip
 board = ttgo-lora32-v1
 framework = arduino
@@ -18,169 +18,40 @@ lib_deps =
   adafruit/Adafruit SSD1306@^2.5.9
   adafruit/Adafruit GFX Library@^1.11.9
   knolleary/PubSubClient@^2.8
-build_flags =
+  throwtheswitch/Unity@^2.6.1
-  -DSERIAL_DEBUG_MODE_FLAG=1
 
-[env:lilygo-t3-v1-6-1-test]
+; --- Hardening flags for all builds ---
-platform = https://github.com/pioarduino/platform-espressif32/releases/download/51.03.07/platform-espressif32.zip
-board = ttgo-lora32-v1
-framework = arduino
-lib_deps =
-  sandeepmistry/LoRa@^0.8.0
-  bblanchon/ArduinoJson@^6.21.5
-  adafruit/Adafruit SSD1306@^2.5.9
-  adafruit/Adafruit GFX Library@^1.11.9
-  knolleary/PubSubClient@^2.8
 build_flags =
-  -DSERIAL_DEBUG_MODE_FLAG=1
+  -fstack-protector-strong
-  -DENABLE_TEST_MODE
+  -D_FORTIFY_SOURCE=2
+  -Wformat -Wformat-security
+  -Wno-format-truncation
 
-[env:lilygo-t3-v1-6-1-868]
+; --- Production: serial off, light-sleep on ---
-platform = https://github.com/pioarduino/platform-espressif32/releases/download/51.03.07/platform-espressif32.zip
+[env:production]
-board = ttgo-lora32-v1
-framework = arduino
-lib_deps =
-  sandeepmistry/LoRa@^0.8.0
-  bblanchon/ArduinoJson@^6.21.5
-  adafruit/Adafruit SSD1306@^2.5.9
-  adafruit/Adafruit GFX Library@^1.11.9
-  knolleary/PubSubClient@^2.8
-build_flags =
-  -DSERIAL_DEBUG_MODE_FLAG=1
-  -DLORA_FREQUENCY_HZ=868E6
-
-[env:lilygo-t3-v1-6-1-868-test]
-platform = https://github.com/pioarduino/platform-espressif32/releases/download/51.03.07/platform-espressif32.zip
-board = ttgo-lora32-v1
-framework = arduino
-lib_deps =
-  sandeepmistry/LoRa@^0.8.0
-  bblanchon/ArduinoJson@^6.21.5
-  adafruit/Adafruit SSD1306@^2.5.9
-  adafruit/Adafruit GFX Library@^1.11.9
-  knolleary/PubSubClient@^2.8
-build_flags =
-  -DSERIAL_DEBUG_MODE_FLAG=1
-  -DENABLE_TEST_MODE
-  -DLORA_FREQUENCY_HZ=868E6
-
-[env:lilygo-t3-v1-6-1-payload-test]
-platform = https://github.com/pioarduino/platform-espressif32/releases/download/51.03.07/platform-espressif32.zip
-board = ttgo-lora32-v1
-framework = arduino
-lib_deps =
-  sandeepmistry/LoRa@^0.8.0
-  bblanchon/ArduinoJson@^6.21.5
-  adafruit/Adafruit SSD1306@^2.5.9
-  adafruit/Adafruit GFX Library@^1.11.9
-  knolleary/PubSubClient@^2.8
-build_flags =
-  -DSERIAL_DEBUG_MODE_FLAG=1
-  -DPAYLOAD_CODEC_TEST
-
-[env:lilygo-t3-v1-6-1-868-payload-test]
-platform = https://github.com/pioarduino/platform-espressif32/releases/download/51.03.07/platform-espressif32.zip
-board = ttgo-lora32-v1
-framework = arduino
-lib_deps =
-  sandeepmistry/LoRa@^0.8.0
-  bblanchon/ArduinoJson@^6.21.5
-  adafruit/Adafruit SSD1306@^2.5.9
-  adafruit/Adafruit GFX Library@^1.11.9
-  knolleary/PubSubClient@^2.8
-build_flags =
-  -DSERIAL_DEBUG_MODE_FLAG=1
-  -DPAYLOAD_CODEC_TEST
-  -DLORA_FREQUENCY_HZ=868E6
-
-[env:lilygo-t3-v1-6-1-prod]
-platform = https://github.com/pioarduino/platform-espressif32/releases/download/51.03.07/platform-espressif32.zip
-board = ttgo-lora32-v1
-framework = arduino
-lib_deps =
-  sandeepmistry/LoRa@^0.8.0
-  bblanchon/ArduinoJson@^6.21.5
-  adafruit/Adafruit SSD1306@^2.5.9
-  adafruit/Adafruit GFX Library@^1.11.9
-  knolleary/PubSubClient@^2.8
-build_flags =
-  -DSERIAL_DEBUG_MODE_FLAG=0
-
-[env:lilygo-t3-v1-6-1-868-prod]
-platform = https://github.com/pioarduino/platform-espressif32/releases/download/51.03.07/platform-espressif32.zip
-board = ttgo-lora32-v1
-framework = arduino
-lib_deps =
-  sandeepmistry/LoRa@^0.8.0
-  bblanchon/ArduinoJson@^6.21.5
-  adafruit/Adafruit SSD1306@^2.5.9
-  adafruit/Adafruit GFX Library@^1.11.9
-  knolleary/PubSubClient@^2.8
-build_flags =
-  -DSERIAL_DEBUG_MODE_FLAG=0
-  -DLORA_FREQUENCY_HZ=868E6
-
-; Diagnostic build: enables extended meter fault telemetry via DEBUG_METER_DIAG.
-; Use for investigating meter error rates; disable in production.
-[env:lilygo-t3-v1-6-1-diag]
-platform = https://github.com/pioarduino/platform-espressif32/releases/download/51.03.07/platform-espressif32.zip
-board = ttgo-lora32-v1
-framework = arduino
-lib_deps =
-  sandeepmistry/LoRa@^0.8.0
-  bblanchon/ArduinoJson@^6.21.5
-  adafruit/Adafruit SSD1306@^2.5.9
-  adafruit/Adafruit GFX Library@^1.11.9
-  knolleary/PubSubClient@^2.8
-build_flags =
-  -DSERIAL_DEBUG_MODE_FLAG=1
-  -DDEBUG_METER_DIAG
-
-; Power-optimised sender build: light-sleep between 1 Hz samples, serial off.
-; Use for long-duration battery-life measurements and production deployments.
-[env:lilygo-t3-v1-6-1-lowpower]
-platform = https://github.com/pioarduino/platform-espressif32/releases/download/51.03.07/platform-espressif32.zip
-board = ttgo-lora32-v1
-framework = arduino
-lib_deps =
-  sandeepmistry/LoRa@^0.8.0
-  bblanchon/ArduinoJson@^6.21.5
-  adafruit/Adafruit SSD1306@^2.5.9
-  adafruit/Adafruit GFX Library@^1.11.9
-  knolleary/PubSubClient@^2.8
 build_flags =
+  ${env.build_flags}
   -DSERIAL_DEBUG_MODE_FLAG=0
   -DENABLE_LIGHT_SLEEP_IDLE=1
 
-; Power-optimised + 868 MHz variant.
+; --- Debug: serial + all diagnostics, real meter data ---
-[env:lilygo-t3-v1-6-1-868-lowpower]
+; Does NOT enable test mode — uses real meter + real LoRa.
-platform = https://github.com/pioarduino/platform-espressif32/releases/download/51.03.07/platform-espressif32.zip
+[env:debug]
-board = ttgo-lora32-v1
-framework = arduino
-lib_deps =
-  sandeepmistry/LoRa@^0.8.0
-  bblanchon/ArduinoJson@^6.21.5
-  adafruit/Adafruit SSD1306@^2.5.9
-  adafruit/Adafruit GFX Library@^1.11.9
-  knolleary/PubSubClient@^2.8
-build_flags =
-  -DSERIAL_DEBUG_MODE_FLAG=0
-  -DENABLE_LIGHT_SLEEP_IDLE=1
-  -DLORA_FREQUENCY_HZ=868E6
-
-; Power-optimised sender build with debug output enabled for validation.
-; Use during the measurement / verification phase.
-[env:lilygo-t3-v1-6-1-lowpower-debug]
-platform = https://github.com/pioarduino/platform-espressif32/releases/download/51.03.07/platform-espressif32.zip
-board = ttgo-lora32-v1
-framework = arduino
-lib_deps =
-  sandeepmistry/LoRa@^0.8.0
-  bblanchon/ArduinoJson@^6.21.5
-  adafruit/Adafruit SSD1306@^2.5.9
-  adafruit/Adafruit GFX Library@^1.11.9
-  knolleary/PubSubClient@^2.8
 build_flags =
+  ${env.build_flags}
   -DSERIAL_DEBUG_MODE_FLAG=1
   -DENABLE_LIGHT_SLEEP_IDLE=1
   -DDEBUG_METER_DIAG
+  -DDD3_DEBUG
+
+; --- Test: synthetic meter samples, payload codec self-test at boot ---
+; Replaces real meter reading with fake 1 Hz data and publishes to test MQTT topic.
+; Use for bench testing without a physical meter attached.
+[env:test]
+build_flags =
+  ${env.build_flags}
+  -DSERIAL_DEBUG_MODE_FLAG=1
+  -DENABLE_TEST_MODE
+  -DPAYLOAD_CODEC_TEST
+  -DDEBUG_METER_DIAG
+  -DDD3_DEBUG