docs: reflect sender catch-up and local-date CSV/history behavior

README.md

@@ -12,6 +12,7 @@ Firmware for LilyGO T3 v1.6.1 (`ESP32 + SX1276 + SSD1306`) that runs in two role
 - Batch payload codec is schema `v3` with a 30-bit `present_mask` over `[t_last-29, t_last]` (`src/payload_codec.cpp`).
 - 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 catch-up mode drains backlog with immediate extra sends when more than one batch is queued (still ACK-gated, single inflight batch).
 - 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.
@@ -90,6 +91,7 @@ Timestamp derivation:
 - jump checks: rollback, wall-time delta mismatch, anchor drift
 
 Sender builds sparse 30-slot windows and sends every `METER_SEND_INTERVAL_MS` (`30s`).
+When backlog is present (`batch_q > 1`), sender transmits additional queued batches immediately after ACK to reduce lag, while keeping stop-and-wait ACK semantics.
 
 Sender diagnostics (serial debug mode):
 - periodic structured `diag:` line with:
@@ -158,11 +160,13 @@ Web timestamp display:
 SD CSV logging (`src/sd_logger.cpp`):
 - header: `ts_utc,ts_hms_local,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_local` is local `HH:MM:SS` derived from `TIMEZONE_TZ`
+- per-day file partition uses local date from `TIMEZONE_TZ`: `/dd3/<device_id>/YYYY-MM-DD.csv`
 
 History parser (`src/web_server.cpp`):
 - accepts both:
   - current layout (`ts_utc,ts_hms_local,p_w,...`)
   - legacy layout (`ts_utc,p_w,...`)
+- daily file lookup prefers local-date filenames and falls back to legacy UTC-date filenames for backward compatibility
 - requires full numeric parse for `ts_utc` and `p_w` (rejects trailing junk)
 
 OLED duplicate display: