add recovery firmware with OTA updater and recovery web interface

Co-authored-by: Cursor <cursoragent@cursor.com>

platformio.ini

@@ -73,6 +73,10 @@ board_upload.flash_size = 16MB
 board_build.app_partition_name = app0
 platform = https://github.com/tasmota/platform-espressif32/releases/download/2026.05.50/platform-espressif32.zip ; Tasmota Arduino Core 3.3.8 based on IDF 5.5.4.260407
 ; platform = https://github.com/tasmota/platform-espressif32/releases/download/2026.09.50/platform-espressif32.zip ; Tasmota Arduino Core 3.3.12 based on IDF 5.5.5
+build_flags =
+  ${common.build_flags}
+  -D EMSESP_HAS_RECOVERY ; installs and falls back to the recovery firmware in the factory partition
+  -D OTA_UPDATER_ANY_PARTITION ; so the recovery firmware can be uploaded into the factory partition
 
 ; 32MB Flash variants
 [espressif32_base_32M]
@@ -163,12 +167,69 @@ build_flags =
 ; XIAO ESP32C - 512KB SRAM & 4MB Flash - https://wiki.seeedstudio.com/xiao_esp32c6_getting_started/
 [env:c6_xiao_4M]
 extends = espressif32_base_4M
-board_build.app_partition_name = app0
 board = seeed_xiao_esp32c6
 build_flags =
   ${common.build_flags}
   -DEMSESP_EN_ONLY
 
+; Crash test builds for the bootloader rollback and the recovery fallback. Install with the web upload, not over
+; serial, since a serial flash boots the recovery. Change EMSESP_CRASH_TEST to pick the test:
+;  1  crashes on every start, so the bootloader rolls back to the previous firmware
+;  2  runs normally until it's confirmed after 2 minutes, then crashes on every start. After 5 crashes in a row
+;     it switches to the recovery firmware. Without one it keeps crashing until reflashed over serial
+[env:crashtest_s3_16M_P]
+extends = env:s3_16M_P
+build_flags =
+  ${espressif32_base_16M.build_flags}
+  -D EMSESP_CRASH_TEST=1
+custom_fw_name = EMS-ESP-CrashTest
+
+; EMS-ESP Recovery - a small app for the factory (boot) partition with an access point and a firmware upload page.
+; Only for boards with a factory partition (16MB). Sources are in ./recovery, the WebUI is built from ./interface.
+;  build:                          pio run -e recovery_s3_16M_P
+;  flash into the boot partition:  pio run -e recovery_s3_16M_P -t upload
+;  run it from app0 like a normal app instead, add an [env:recovery_s3_16M_P] section to pio_local.ini with custom_app_offset =
+;  develop the WebUI with a mock:  cd interface && pnpm recovery
+[recovery_base]
+extends = espressif32_base_16M
+board_build.app_partition_name = boot
+build_src_filter = -<*> +<../recovery/>
+build_flags =
+  ${factory_settings.build_flags}
+  -std=gnu++20 -Os
+  -D OTA_UPDATER_ANY_PARTITION
+  -D CONFIG_ASYNC_TCP_RUNNING_CORE=1
+  -D CONFIG_ASYNC_TCP_STACK_SIZE=8192
+build_unflags =
+  ${common.core_unbuild_flags}
+lib_ldf_mode = chain
+lib_deps =
+  bblanchon/ArduinoJson @ 7.4.3
+  ESP32Async/AsyncTCP @ 3.5.0
+  ESP32Async/ESPAsyncWebServer @ 3.12.1
+extra_scripts =
+  pre:scripts/build_recovery_interface.py
+  post:scripts/set_app_desc.py
+  post:scripts/rename_fw.py
+  post:scripts/upload_factory.py
+upload_protocol = esptool
+custom_app_offset = 0x10000
+custom_fw_name = EMS-ESP-Recovery
+custom_version_file = recovery/recovery_version.h
+custom_version_define = RECOVERY_VERSION
+
+[env:recovery_s_16M]
+extends = recovery_base
+board = s_16M
+
+[env:recovery_s_16M_P]
+extends = recovery_base
+board = s_16M_P
+
+[env:recovery_s3_16M_P]
+extends = recovery_base
+board = s3_16M_P
+
 ; foundation for building and testing natively, standalone without an ESP32
 ; use the `standalone` environment instead of `native` for testing
 [env:native]
@@ -199,6 +260,7 @@ build_src_filter =
   -<../lib/uuid-syslog>
   -<../lib/eModbus>
   -<../lib/OneWire>
+  -<../lib/OtaUpdater>
   -<../src/core/ModuleLibrary.cpp>
 lib_ldf_mode = off
 lib_deps =
@@ -242,6 +304,7 @@ build_src_filter =
   -<../lib/uuid-syslog>
   -<../lib/eModbus>
   -<../lib/OneWire>
+  -<../lib/OtaUpdater>
   -<../src/core/ModuleLibrary.cpp>
 lib_ldf_mode = off
 lib_deps = Unity