Document hourly and first-sync sender fault counter resets

README.md

@@ -13,6 +13,7 @@ Firmware for LilyGO T3 v1.6.1 (`ESP32 + SX1276 + SSD1306`) that runs in two role
 - Sender retries reuse cached encoded payload bytes (no re-encode on retry path).
 - Sender ACK receive windows adapt from observed ACK RTT + miss streak.
 - Sender only starts normal metering/transmit flow after valid time bootstrap from receiver ACK.
+- Sender fault counters are reset at first valid time sync and again at each UTC hour boundary.
 - Receiver runs STA mode if stored config is valid and connects, otherwise AP fallback.
 
 ## LoRa Protocol
@@ -58,8 +59,12 @@ Sender boot starts in sync-only mode:
 After valid ACK time:
 - `time_set_utc()` is called
 - `g_time_acquired=true`
+- sender fault counters are reset once (`err_m`, `err_d`, `err_tx`, last-error state)
 - normal 1 Hz sampling + periodic batch transmission starts
 
+After initial sync:
+- sender fault counters are reset again once per UTC hour when the hour index changes (`HH:00 UTC` boundary)
+
 Timezone:
 - `TIMEZONE_TZ` from `include/config.h` is applied in `time_manager`.
 - Web/OLED local-time rendering uses this timezone.
@@ -125,6 +130,10 @@ State JSON (`src/json_codec.cpp`) includes:
 - `err_last`, `rx_reject`, `rx_reject_text`
 - non-zero fault counters when available
 
+Sender fault counter lifecycle:
+- counters are cumulative only within the current UTC-hour window after first sync
+- counters reset on first valid sender time sync and at each subsequent UTC hour boundary
+
 Home Assistant discovery:
 - enabled by `ENABLE_HA_DISCOVERY=true`
 - publishes to `homeassistant/sensor/<device_id>/<key>/config`