fix(blastware_file, server): enhance logging and correct chunk handling for accurate data processing

sfm/server.py

@@ -885,21 +885,22 @@ def device_event_blastware_file(
         def _do():
             with _build_client(port, baud, host, tcp_port, timeout=120.0) as client:
                 info = client.connect()
-                # Use stop_after_metadata=True (full_waveform=False) with 1 extra
-                # chunk after "Project:".  For any record time, the pre-metadata
-                # section of the 5A stream naturally carries proportionally more
-                # ADC data for longer events — so "1 extra chunk" produces the
-                # correct body length regardless of record time.
+                # Use stop_after_metadata=True (full_waveform=False) with 0 extra
+                # chunks after "Project:".  Confirmed from 4-26-26 BW RS-232 capture
+                # of "copy event to file" on a 2-sec Continuous event (key=01110000):
+                # BW sends the termination frame IMMEDIATELY after the chunk that
+                # contains "Project:" — no extra chunk is downloaded first.
+                # extra_chunks_after_metadata=1 was WRONG: it downloaded one additional
+                # chunk (counter = last_data_counter + 0x0400) adding ~1053 spurious
+                # bytes to the body, causing Blastware to reject the file.
                 #
                 # full_waveform=True (natural end-of-stream) downloads ALL chunks
                 # including post-event silence (35+ chunks for a 9-sec event at
                 # 1024 sps) — this produces 24KB+ files that Blastware rejects.
-                # Confirmed from file size comparison: BW 1-sec=4400B, BW 3-sec=8114B,
-                # per-second delta 1857 bytes — matches pre-metadata frame scaling.
                 events = client.get_events(
                     full_waveform=False,
                     stop_after_index=index,
-                    extra_chunks_after_metadata=1,
+                    extra_chunks_after_metadata=0,
                 )
                 matching = [ev for ev in events if ev.index == index]
                 return matching[0] if matching else None, info