Refresh README and add firmware requirements for Rust port

README.md

@@ -1,104 +1,100 @@
 # DD3-LoRa-Bridge-MultiSender
 
-Firmware for LilyGO T3 v1.6.1 (`ESP32 + SX1276 + SSD1306`) that runs as either:
-- `Sender` (PIN `GPIO14` HIGH): reads one IEC 62056-21 meter, batches samples, sends over LoRa.
-- `Receiver` (PIN `GPIO14` LOW): receives/ACKs batches, publishes MQTT, serves web UI, logs to SD.
+Firmware for LilyGO T3 v1.6.1 (`ESP32 + SX1276 + SSD1306`) that runs in two roles:
+- `Sender` (`GPIO14` HIGH): reads one IEC 62056-21 meter, builds 30-slot sparse batches, sends via LoRa.
+- `Receiver` (`GPIO14` LOW): receives/ACKs batches, publishes MQTT, serves web UI, logs to SD.
 
-## Current Architecture
+## Architecture Summary
 
-- Single codebase, role selected at boot via `detect_role()` (`include/config.h`, `src/config.cpp`).
-- LoRa link uses explicit CRC16 frame protection in firmware (`src/lora_transport.cpp`).
-- Sender batches up to `30` samples and retries on missing ACK (`BATCH_MAX_RETRIES=2`, retry policy `Keep`).
-- Sender meter parsing is decoupled from LoRa ACK waits using a dedicated FreeRTOS reader task + queue (`src/main.cpp`).
-- Batch payload codec is schema v3 and uses a sparse `present_mask` over a 30-second window (no schema v2 compatibility).
-- Sender derives epoch timestamps from meter Sekundenindex (`0-0:96.8.0*255`) using an epoch anchor when time is synced.
-- Receiver uses STA mode when config is valid, otherwise AP fallback with web config.
-- No debug auto-reboot timer is active in normal firmware loops.
+- Single codebase, role selected at boot by `detect_role()` (`src/config.cpp`).
+- LoRa transport is wrapped with firmware-level CRC16-CCITT (`src/lora_transport.cpp`).
+- Sender meter ingest is decoupled from LoRa waits via FreeRTOS meter reader task + queue on ESP32 (`src/main.cpp`).
+- Batch payload codec is schema `v3` with a 30-bit `present_mask` over `[t_last-29, t_last]` (`src/payload_codec.cpp`).
+- Sender only starts normal metering/transmit flow after valid time bootstrap from receiver ACK.
+- Receiver runs STA mode if stored config is valid and connects, otherwise AP fallback.
 
-## LoRa Frame Protocol (Current)
+## LoRa Protocol
 
-On-air frame format:
+On-air frame:
 
 `[msg_kind:1][device_short_id:2][payload...][crc16:2]`
 
 `msg_kind`:
-- `0` = `BatchUp`
-- `1` = `AckDown`
+- `0`: `BatchUp`
+- `1`: `AckDown`
 
-### `BatchUp`
+### BatchUp
 
-Transport is chunked (`batch_id`, `chunk_index`, `chunk_count`, `total_len`) and reassembled before payload decode.
+Transport layer chunks payload into:
 
-Payload codec (`src/payload_codec.cpp`) currently uses:
-- `kMagic=0xDDB3`
-- `kSchema=3`
-- metadata: sender, batch, `t_last`, `present_mask`, battery, fault counters
-- data arrays: `energy_wh[]`, `p1_w[]`, `p2_w[]`, `p3_w[]`
+`[batch_id_le:2][chunk_index:1][chunk_count:1][total_len_le:2][chunk_payload...]`
 
-`present_mask` is a 30-bit second map in the `[t_last-29, t_last]` window.
-Only set bits carry samples, so missing seconds are explicitly represented.
+Receiver reassembles all chunks before decode.
 
-`n == 0` is valid for sync request packets (`present_mask == 0`).
+Payload codec (`schema=3`, magic `0xDDB3`) carries:
+- metadata: sender ID, batch ID, `t_last`, `present_mask`, battery mV, error counters
+- arrays per present sample: `energy_wh[]`, `p1_w[]`, `p2_w[]`, `p3_w[]`
 
-### `AckDown` (7 bytes)
+`n == 0` with `present_mask == 0` is valid and used for sync request packets.
+
+### AckDown (7 bytes payload)
 
 `[flags:1][batch_id_be:2][epoch_utc_be:4]`
 
 - `flags bit0`: `time_valid`
-- Receiver repeats ACK (`ACK_REPEAT_COUNT=3`, `ACK_REPEAT_DELAY_MS=200`).
-- Sender accepts time only if `time_valid=1` and `epoch >= MIN_ACCEPTED_EPOCH_UTC` (`2026-02-01 00:00:00 UTC`).
+- ACK is repeated (`ACK_REPEAT_COUNT=3`, `ACK_REPEAT_DELAY_MS=200`)
+- Sender sets local time only if `time_valid=1` and `epoch >= MIN_ACCEPTED_EPOCH_UTC` (`2026-02-01 00:00:00 UTC`)
 
-## Time Bootstrap Guardrail
+## Time Bootstrap and Timezone
 
-On sender boot:
+Sender boot starts in sync-only mode:
 - `g_time_acquired=false`
-- no normal sampling/transmit yet
-- sync request every `SYNC_REQUEST_INTERVAL_MS` (15s)
+- sends sync requests every `SYNC_REQUEST_INTERVAL_MS` (`15s`)
+- does not run normal 1 Hz sample/batch flow yet
 
-Only after valid ACK time is received:
-- system time is set
-- normal 1 Hz sampling and periodic LoRa batch transmit start
+After valid ACK time:
+- `time_set_utc()` is called
+- `g_time_acquired=true`
+- normal 1 Hz sampling + periodic batch transmission starts
 
-This blocks pre-threshold timestamps from MQTT/SD paths.
-
-Timezone handling:
-- Local time rendering uses `TIMEZONE_TZ` from `include/config.h`.
-- Default value is `CET-1CEST,M3.5.0/2,M10.5.0/3` and can be changed at compile time.
+Timezone:
+- `TIMEZONE_TZ` from `include/config.h` is applied in `time_manager`.
+- Web/OLED local-time rendering uses this timezone.
+- Default: `CET-1CEST,M3.5.0/2,M10.5.0/3`.
 
 ## Sender Meter Path
 
-Implemented in `src/meter_driver.cpp` + sender loop in `src/main.cpp`:
+Implemented by `src/meter_driver.cpp` and sender loop in `src/main.cpp`:
+- UART: `Serial2`, `GPIO34`, `9600 7E1`
+- ESP32 RX buffer enlarged to `8192`
+- Frame detection `/ ... !`, timeout `METER_FRAME_TIMEOUT_MS=3000`
+- Parsed OBIS fields:
+  - `0-0:96.8.0*255` meter Sekundenindex (hex u32)
+  - `1-0:1.8.0` total energy (auto scales Wh -> kWh when unit is Wh)
+  - `1-0:16.7.0` total active power
+  - `1-0:36.7.0`, `56.7.0`, `76.7.0` phase powers
 
-- UART: `Serial2`, RX pin `GPIO34` (`PIN_METER_RX`), `9600 7E1`
-- ESP32 RX buffer is enlarged to `8192` bytes to survive long LoRa blocking sections.
-- Frame detection: starts at `'/'`, ends at `'!'`, timeout protection included (`METER_FRAME_TIMEOUT_MS=3000`).
-- Parsing runs in a dedicated sender task and is handed to the main sender loop via queue.
-- Parsed OBIS values:
-  - `0-0:96.8.0*255` (meter Sekundenindex, 4-byte hex)
-  - `1-0:1.8.0` (total energy)
-  - `1-0:16.7.0` (total power)
-  - `1-0:36.7.0`, `56.7.0`, `76.7.0` (phase powers)
-- `1-0:1.8.0*Wh` is automatically scaled to kWh
+Timestamp derivation:
+- anchor offset: `epoch_offset = epoch_now - meter_seconds`
+- sample epoch: `ts_utc = meter_seconds + epoch_offset`
+- jump checks: rollback, wall-time delta mismatch, anchor drift
 
-Timestamping/validation on sender:
-- Anchor when time is valid: `epoch_offset = epoch_now - meter_seconds`.
-- Derived sample time: `ts_utc = meter_seconds + epoch_offset`.
-- Meter-time checks: monotonicity and `delta_meter_seconds` vs elapsed wall time (with tolerance) plus anchor drift checks.
-- On detected jump/drift, sender records meter fault and resulting timestamp discontinuities propagate through `present_mask` to receiver.
-
-Sender samples every second and transmits batches every 30 seconds.
+Sender builds sparse 30-slot windows and sends every `METER_SEND_INTERVAL_MS` (`30s`).
 
 ## Receiver Behavior
 
-For valid `BatchUp` decode:
-1. Reassemble chunks and decode payload.
+For decoded `BatchUp`:
+1. Reassemble and decode.
 2. Send `AckDown` immediately.
-3. Drop duplicate batches per sender (`batch_id` tracking).
-4. Track duplicate stats per sender: absolute duplicates, total received, duplicate percentage, last duplicate timestamp.
-5. If `n==0`: treat as sync request only.
-6. Else reconstruct timestamps from `t_last` + `present_mask`, preserving skipped seconds, then log to SD, update web UI, publish MQTT.
+3. Track duplicates per configured sender (`EXPECTED_SENDER_IDS`).
+4. If duplicate: update duplicate counters/time, skip data write/publish.
+5. If `n==0`: sync request path only.
+6. Else reconstruct each sample timestamp from `t_last + present_mask`, then:
+   - append to SD CSV
+   - publish MQTT state
+   - update web status and last batch table
 
-## MQTT Topics and Payloads
+## MQTT
 
 State topic:
 - `smartmeter/<device_id>/state`
@@ -106,29 +102,43 @@ State topic:
 Fault topic (retained):
 - `smartmeter/<device_id>/faults`
 
-State JSON fields (`src/json_codec.cpp`):
+State JSON (`src/json_codec.cpp`) includes:
 - `id`, `ts`, `e_kwh`
 - `p_w`, `p1_w`, `p2_w`, `p3_w`
 - `bat_v`, `bat_pct`
-- optional link fields: `rssi`, `snr`
-- fault/reject fields: `err_last`, `rx_reject`, `rx_reject_text` (+ non-zero counters)
+- optional link: `rssi`, `snr`
+- `err_last`, `rx_reject`, `rx_reject_text`
+- non-zero fault counters when available
 
-Home Assistant discovery is enabled (`ENABLE_HA_DISCOVERY=true`) and publishes config topics under:
-- `homeassistant/sensor/<device_id>/<key>/config`
+Home Assistant discovery:
+- enabled by `ENABLE_HA_DISCOVERY=true`
+- publishes to `homeassistant/sensor/<device_id>/<key>/config`
 
-## Web UI, Wi-Fi, Storage
+## Web UI, Wi-Fi, SD
 
-- Wi-Fi/MQTT/NTP/web-auth config persists in Preferences (`wifi_manager`).
+- Wi-Fi/MQTT/NTP/web-auth config is stored in Preferences.
 - AP fallback SSID prefix: `DD3-Bridge-`.
 - Default web credentials: `admin/admin`.
-- SD logging enabled (`ENABLE_SD_LOGGING=true`).
-- Sender-specific web status includes duplicate-batch counters and the last duplicate time.
-- Sender-specific OLED page shows duplicate rate as `pct (absolute)` and last duplicate as `HH:MM`.
+- AP auth requirement is controlled by `WEB_AUTH_REQUIRE_AP` (default `false`).
+- STA auth requirement is controlled by `WEB_AUTH_REQUIRE_STA` (default `true`).
+
+Web timestamp display:
+- human-facing timestamps show `epoch (HH:MM:SS TZ)` in local configured timezone.
+
+SD CSV logging (`src/sd_logger.cpp`):
+- header: `ts_utc,ts_hms_utc,p_w,p1_w,p2_w,p3_w,e_kwh,bat_v,bat_pct,rssi,snr,err_m,err_d,err_tx,err_last`
+- `ts_hms_utc` is UTC `HH:MM:SS`
+
+History parser (`src/web_server.cpp`):
+- expects the current CSV layout above
+- legacy CSV layouts are not parsed (no backward compatibility)
+
+OLED duplicate display:
+- receiver sender-pages show duplicate rate as `pct (absolute)` and last duplicate as `HH:MM`.
 
 ## Build Environments
 
 From `platformio.ini`:
-
 - `lilygo-t3-v1-6-1`
 - `lilygo-t3-v1-6-1-test`
 - `lilygo-t3-v1-6-1-868`
@@ -141,10 +151,12 @@ From `platformio.ini`:
 Example:
 
 ```bash
-~/.platformio/penv/bin/pio run -e lilygo-t3-v1-6-1
+python -m platformio run -e lilygo-t3-v1-6-1
 ```
 
 ## Test Mode
 
-`ENABLE_TEST_MODE` replaces normal sender/receiver loops with dedicated test loops (`src/test_mode.cpp`).
-It sends/receives JSON test frames and publishes to `smartmeter/<device_id>/test`.
+`ENABLE_TEST_MODE` replaces normal loops with `test_sender_loop` / `test_receiver_loop` (`src/test_mode.cpp`):
+- Sender emits periodic JSON test payloads over LoRa.
+- Receiver decodes test payloads, updates display test codes, publishes MQTT to:
+  - `smartmeter/<device_id>/test`