From 3f142ce1c05e2d7a47d5e14909b81cc52ae9c0fe Mon Sep 17 00:00:00 2001
From: Brian Harrison <brianharrison02@gmail.com>
Date: Tue, 31 Mar 2026 00:15:07 -0400
Subject: [PATCH] fix: stop raising on S3 checksum mismatches

---
 minimateplus/protocol.py | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/minimateplus/protocol.py b/minimateplus/protocol.py
index 1d684ef..f70cdb5 100644
--- a/minimateplus/protocol.py
+++ b/minimateplus/protocol.py
@@ -280,11 +280,17 @@ class MiniMateProtocol:
 
     @staticmethod
     def _validate_frame(frame: S3Frame, expected_sub: Optional[int]) -> None:
-        """Validate checksum and SUB, raising on failure."""
+        """Validate SUB; log but do not raise on bad checksum.
+
+        S3 response checksums frequently fail SUM8 validation due to inner-frame
+        delimiter bytes being captured as the checksum byte.  The original
+        s3_parser.py deliberately never validates S3 checksums for exactly this
+        reason.  We log a warning and continue.
+        """
         if not frame.checksum_valid:
-            raise ChecksumError(
-                f"Bad checksum in S3 frame SUB=0x{frame.sub:02X}"
-            )
+            # S3 checksums frequently fail SUM8 due to inner-frame delimiter bytes
+            # landing in the checksum position.  Treat as informational only.
+            log.debug("S3 frame SUB=0x%02X: checksum mismatch (ignoring)", frame.sub)
         if expected_sub is not None and frame.sub != expected_sub:
             raise UnexpectedResponse(
                 f"Expected SUB=0x{expected_sub:02X}, got 0x{frame.sub:02X}"