diff --git a/parsers/s3_analyzer.py b/parsers/s3_analyzer.py
index c86477d..6feb32b 100644
--- a/parsers/s3_analyzer.py
+++ b/parsers/s3_analyzer.py
@@ -53,7 +53,9 @@ SUB_TABLE: dict[int, tuple[str, str, str]] = {
     0x82: ("TRIGGER_CONFIG_WRITE",      "BW→S3", "0x1C bytes; trigger config block; mirrors SUB 1C"),
     0x83: ("TRIGGER_WRITE_CONFIRM",     "BW→S3", "Short frame; commit step after 0x82"),
     # S3→BW responses
+    0x5A: ("BULK_WAVEFORM_STREAM",       "BW→S3", "Bulk waveform chunk request; response is A5 stream"),
     0xA4: ("POLL_RESPONSE",             "S3→BW", "Response to SUB 5B poll"),
+    0xA5: ("BULK_WAVEFORM_RESPONSE",    "S3→BW", "Response to SUB 5A; waveform chunks + metadata"),
     0xFE: ("FULL_CONFIG_RESPONSE",      "S3→BW", "Response to SUB 01"),
     0xF9: ("CHANNEL_CONFIG_RESPONSE",   "S3→BW", "Response to SUB 06"),
     0xF7: ("EVENT_INDEX_RESPONSE",      "S3→BW", "Response to SUB 08; contains backlight/power-save"),
diff --git a/parsers/s3_parser.py b/parsers/s3_parser.py
index 4b8a2bc..2bb3de1 100644
--- a/parsers/s3_parser.py
+++ b/parsers/s3_parser.py
@@ -33,7 +33,7 @@ STX = 0x02
 ETX = 0x03
 ACK = 0x41
 
-__version__ = "0.2.4"
+__version__ = "0.2.5"
 
 
 @dataclass
@@ -220,32 +220,22 @@ def parse_s3(blob: bytes, trailer_len: int) -> List[Frame]:
                 trailer_end = trailer_start + trailer_len
                 trailer = blob[trailer_start:trailer_end]
 
-                chk_valid = None
-                chk_type = None
-                chk_hex = None
-                payload = bytes(body)
-
-                if len(body) >= 1:
-                    received_chk = body[-1]
-                    computed_chk = checksum8_sum(bytes(body[:-1]))
-                    if computed_chk == received_chk:
-                        chk_valid = True
-                        chk_type = "SUM8"
-                        chk_hex = f"{received_chk:02x}"
-                        payload = bytes(body[:-1])
-                    else:
-                        chk_valid = False
-
+                # S3 checksums are deliberately not validated here.
+                # Large S3 responses (A5 bulk waveform, E5 compliance) embed
+                # inner DLE+ETX sub-frame terminators whose trailing 0x03 byte
+                # lands where the parser would expect the SUM8 checksum, causing
+                # false failures.  The live protocol (protocol.py _validate_frame)
+                # also skips S3 checksum enforcement for the same reason.
                 frames.append(Frame(
                     index=idx,
                     start_offset=start_offset,
                     end_offset=end_offset,
                     payload_raw=bytes(body),
-                    payload=payload,
+                    payload=bytes(body),
                     trailer=trailer,
-                    checksum_valid=chk_valid,
-                    checksum_type=chk_type,
-                    checksum_hex=chk_hex
+                    checksum_valid=None,
+                    checksum_type=None,
+                    checksum_hex=None
                 ))
 
                 idx += 1