Address code review feedback

- Make getRetryStartOffset() delegate to getLastCompleteSegmentStart()
- Add validation for negative remainingCount in BlobAsyncClientBase
- Improve message formatting in createRetryableException()

Co-authored-by: gunjansingh-msft <[email protected]>

Author: Copilot

sdk/storage/azure-storage-blob/src/main/java/com/azure/storage/blob/specialized/BlobAsyncClientBase.java

@@ -1427,12 +1427,19 @@ Mono<BlobDownloadAsyncResponse> downloadStreamWithResponse(BlobRange range, Down
                                     .parseRetryStartOffset(throwable.getMessage());
                                 if (retryStartOffset >= 0) {
                                     long remainingCount = finalCount - retryStartOffset;
-                                    retryRange = new BlobRange(initialOffset + retryStartOffset, remainingCount);
-
-                                    LOGGER.info(
-                                        "Structured message smart retry from exception: resuming from offset {} "
-                                            + "(initial={}, parsed={})",
-                                        initialOffset + retryStartOffset, initialOffset, retryStartOffset);
+                                    // Validate remainingCount to avoid negative values
+                                    if (remainingCount <= 0) {
+                                        LOGGER.warning("Retry offset {} exceeds finalCount {}, using fallback",
+                                            retryStartOffset, finalCount);
+                                        retryRange = new BlobRange(initialOffset + offset, newCount);
+                                    } else {
+                                        retryRange = new BlobRange(initialOffset + retryStartOffset, remainingCount);
+
+                                        LOGGER.info(
+                                            "Structured message smart retry from exception: resuming from offset {} "
+                                                + "(initial={}, parsed={})",
+                                            initialOffset + retryStartOffset, initialOffset, retryStartOffset);
+                                    }
                                 } else {
                                     // Fallback to normal retry logic if no offset found
                                     retryRange = new BlobRange(initialOffset + offset, newCount);

sdk/storage/azure-storage-common/src/main/java/com/azure/storage/common/implementation/structuredmessage/StructuredMessageDecoder.java

@@ -130,11 +130,14 @@ public long getLastCompleteSegmentStart() {
     /**
      * Returns the canonical absolute byte index (0-based) that should be used to resume a failed/incomplete download.
      * This MUST be used directly as the Range header start value: "Range: bytes={retryStartOffset}-"
+     * 
+     * <p>This is equivalent to {@link #getLastCompleteSegmentStart()} but provides a clearer semantic name
+     * for the smart retry use case.</p>
      *
      * @return The absolute byte index for the retry start offset.
      */
     public long getRetryStartOffset() {
-        return lastCompleteSegmentStart;
+        return getLastCompleteSegmentStart();
     }
 
     /**

sdk/storage/azure-storage-common/src/main/java/com/azure/storage/common/policy/StorageContentValidationDecoderPolicy.java

@@ -220,9 +220,12 @@ private IOException createRetryableException(DecoderState state, String message,
         long decodedSoFar = state.decoder.getTotalDecodedPayloadBytes();
         long expectedLength = state.decoder.getMessageLength();
 
+        // Build message components for clarity
+        long displayExpected = expectedLength > 0 ? expectedLength : 0;
+        String originalMessage = message != null ? message : "";
+
         String fullMessage = String.format("Incomplete structured message: decoded %d of %d bytes. %s%d. %s",
-            decodedSoFar, expectedLength > 0 ? expectedLength : 0, RETRY_OFFSET_TOKEN, retryOffset,
-            message != null ? message : "");
+            decodedSoFar, displayExpected, RETRY_OFFSET_TOKEN, retryOffset, originalMessage);
 
         LOGGER.atInfo()
             .addKeyValue("retryOffset", retryOffset)