fix: correct event count field offset and eliminate count_events() walk

_decode_event_count: read uint16 BE at offset 10 (confirmed 2026-04-10 from
live BE11529 event index — data[10:12]=0x0006=6, matches device LCD).
Previous uint32 at offset 3 always returned 1 regardless of event count.

ach_server.py: use device_info.event_count (already fetched during connect())
instead of calling count_events() separately. This saves 2*N round-trips and
avoids the 1F linked-list walk which was overcounting on some devices.
count_events() kept as fallback when connect() is skipped (--events-only).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

bridges/ach_server.py

@@ -216,14 +216,21 @@ class AchSession:
             unit_key = serial or self.peer  # fall back to IP if no serial
             last_count = state.get(unit_key, {}).get("event_count", 0)
 
+            # Use the event count already read from the event index during connect().
+            # This is fast (no extra round-trips) and confirmed accurate (matches LCD).
+            # Falls back to count_events() only if connect() wasn't called.
+            if device_info is not None:
+                current_count = device_info.event_count
+            else:
                 try:
                     current_count = client.count_events()
-                log.info("  Unit has %d stored event(s); last downloaded count: %d",
-                         current_count, last_count)
                 except Exception as exc:
                     log.error("  [FAIL] count_events failed: %s", exc)
                     return
 
+            log.info("  Unit has %d stored event(s); last downloaded count: %d",
+                     current_count, last_count)
+
             if current_count <= last_count:
                 log.info("  [OK] No new events since last call-home -- nothing to download")
                 log.info("Session complete (no new events) -> %s", session_dir)

minimateplus/client.py

@@ -910,36 +910,25 @@ def _decode_event_count(data: bytes) -> int:
     """
     Extract stored event count from SUB F7 (EVENT_INDEX_RESPONSE) payload.
 
-    Layout per §7.4 (offsets from data section start):
+    Confirmed 2026-04-10 from live BE11529 event index (88 bytes):
-      +00:  00 58 09  — total index size or record count ❓
+      data[10:12]  uint16 BE  = stored event count  (confirmed: 0x0006 = 6, matches LCD)
-      +03:  00 00 00 01  — possibly stored event count = 1 ❓
+      data[3:7]    uint32 BE  = 0x00000001           (NOT the count — meaning TBD)
 
-    We use bytes +03..+06 interpreted as uint32 BE as the event count.
+    Previous implementation read uint32 at offset 3, which returned 1 regardless
-    This is inferred (🔶) — the exact meaning of the first 3 bytes is unclear.
+    of how many events were stored.
     """
-    if len(data) < 7:
+    if len(data) < 12:
         log.warning("event index payload too short (%d bytes), assuming 0 events", len(data))
         return 0
 
-    # Log the full payload so we can reverse-engineer the format
+    count = struct.unpack_from(">H", data, 10)[0]
-    log.warning("event_index raw (%d bytes total):", len(data))
-    for off in range(0, len(data), 16):
-        chunk = data[off:off+16]
-        hex_part = " ".join(f"{b:02x}" for b in chunk)
-        asc_part = "".join(chr(b) if 0x20 <= b < 0x7f else "." for b in chunk)
-        log.warning("  [%04x]: %-47s  %s", off, hex_part, asc_part)
 
-    # Try the uint32 at +3 first
+    # Sanity check: MiniMate Plus max storage is ~1000 events
-    count = struct.unpack_from(">I", data, 3)[0]
-
-    # Sanity check: MiniMate Plus manual says max ~1000 events
     if count > 1000:
-        log.warning(
+        log.warning("event count %d looks unreasonably large — clamping to 0", count)
-            "event count %d looks unreasonably large — clamping to 0", count
-        )
         return 0
 
-    log.warning("event_index decoded count=%d (uint32 BE at offset +3)", count)
+    log.debug("event_index decoded count=%d (uint16 BE at offset 10)", count)
     return count