diff --git a/crates/ecstore/src/set_disk/ops/object.rs b/crates/ecstore/src/set_disk/ops/object.rs
index 1f9e7e86f..a1d88b1b9 100644
--- a/crates/ecstore/src/set_disk/ops/object.rs
+++ b/crates/ecstore/src/set_disk/ops/object.rs
@@ -4043,6 +4043,7 @@ mod transition_upload_integrity_tests {
     use crate::services::tier::test_util::register_mock_tier;
     use crate::storage_api_contracts::object::{ObjectIO as _, ObjectOperations as _};
     use http::HeaderMap;
+    use std::path::PathBuf;
 
     async fn assert_local_source_intact(set_disks: &Arc<SetDisks>, bucket: &str, object: &str, payload: &[u8]) {
         let mut restored = Vec::new();
@@ -4113,6 +4114,56 @@ mod transition_upload_integrity_tests {
         }
     }
 
+    async fn corrupt_shard_at(path: PathBuf, position: ShardCorruptionPosition) {
+        let mut bytes = tokio::fs::read(&path).await.expect("committed shard should be readable");
+        assert!(!bytes.is_empty(), "committed shard should not be empty");
+        let offset = match position {
+            ShardCorruptionPosition::First => 0,
+            ShardCorruptionPosition::Middle => bytes.len() / 2,
+            ShardCorruptionPosition::Last => bytes.len() - 1,
+        };
+        bytes[offset] ^= 0xff;
+        tokio::fs::write(&path, bytes)
+            .await
+            .expect("committed shard corruption should be written");
+    }
+
+    #[derive(Clone, Copy, Debug)]
+    enum ShardCorruptionPosition {
+        First,
+        Middle,
+        Last,
+    }
+
+    impl ShardCorruptionPosition {
+        fn label(self) -> &'static str {
+            match self {
+                ShardCorruptionPosition::First => "first",
+                ShardCorruptionPosition::Middle => "middle",
+                ShardCorruptionPosition::Last => "last",
+            }
+        }
+    }
+
+    async fn corrupt_beyond_read_quorum(
+        temp_dirs: &[tempfile::TempDir],
+        bucket: &str,
+        object: &str,
+        data_dir: Uuid,
+        parity_blocks: usize,
+        position: ShardCorruptionPosition,
+    ) {
+        for temp_dir in temp_dirs.iter().take(parity_blocks + 1) {
+            let shard = temp_dir
+                .path()
+                .join(bucket)
+                .join(object)
+                .join(data_dir.to_string())
+                .join("part.1");
+            corrupt_shard_at(shard, position).await;
+        }
+    }
+
     #[tokio::test]
     #[serial_test::serial]
     async fn partial_remote_acceptance_cleans_exact_candidate_and_preserves_source() {
@@ -4142,6 +4193,98 @@ mod transition_upload_integrity_tests {
         assert_local_source_intact(&set_disks, bucket, object, &payload).await;
     }
 
+    #[tokio::test]
+    #[serial_test::serial]
+    async fn real_bitrot_producer_failures_do_not_commit_transition() {
+        let (temp_dirs, disk_stores, set_disks) = hermetic_set_disks(4).await;
+        let tier_name = format!("COLDTIER{}", &Uuid::new_v4().simple().to_string()[..8]).to_uppercase();
+        let backend = register_mock_tier(&runtime_sources::global_tier_config_mgr(), &tier_name).await;
+
+        for position in [
+            ShardCorruptionPosition::First,
+            ShardCorruptionPosition::Middle,
+            ShardCorruptionPosition::Last,
+        ] {
+            let bucket = format!("transition-real-bitrot-{}", position.label());
+            let object = format!("{}-corrupt.bin", position.label());
+            let payload = vec![0x41; 2 * 1024 * 1024];
+            let original = write_source(&set_disks, &disk_stores, &bucket, &object, &payload).await;
+            let (source, _, _) = set_disks
+                .get_object_fileinfo(
+                    &bucket,
+                    &object,
+                    &ObjectOptions {
+                        no_lock: true,
+                        metadata_cache_safe: false,
+                        ..Default::default()
+                    },
+                    true,
+                    false,
+                )
+                .await
+                .expect("source metadata should be available before shard corruption");
+            let data_dir = source.data_dir.expect("source object should have a data directory");
+
+            corrupt_beyond_read_quorum(&temp_dirs, &bucket, &object, data_dir, source.erasure.parity_blocks, position).await;
+
+            let error = set_disks
+                .transition_object(&bucket, &object, &transition_options(&original, tier_name.clone()))
+                .await
+                .expect_err("producer bitrot failure must not commit transition metadata");
+            assert!(
+                matches!(
+                    error,
+                    StorageError::FileCorrupt
+                        | StorageError::ErasureReadQuorum
+                        | StorageError::InsufficientReadQuorum(_, _)
+                        | StorageError::LessData
+                        | StorageError::Io(_)
+                ),
+                "{position:?}: unexpected transition producer error: {error:?}"
+            );
+            let (after, _, _) = set_disks
+                .get_object_fileinfo(
+                    &bucket,
+                    &object,
+                    &ObjectOptions {
+                        no_lock: true,
+                        metadata_cache_safe: false,
+                        ..Default::default()
+                    },
+                    true,
+                    false,
+                )
+                .await
+                .expect("failed transition must leave metadata readable");
+            assert_eq!(
+                after.data_dir,
+                Some(data_dir),
+                "{position:?}: transition must not release the source data dir"
+            );
+            assert_ne!(
+                after.transition_status, TRANSITION_COMPLETE,
+                "{position:?}: transition status must remain incomplete after producer bitrot failure"
+            );
+        }
+
+        assert_eq!(
+            backend.put_count().await,
+            3,
+            "each bitrot case should create one remote cleanup candidate"
+        );
+        assert_eq!(backend.remove_count().await, 3, "each bitrot candidate must be removed before returning");
+        assert_eq!(
+            backend.remove_versions().await,
+            backend.put_versions().await,
+            "bitrot cleanup must target the exact remote version returned by PUT"
+        );
+        assert_eq!(
+            backend.object_count().await,
+            0,
+            "bitrot producer failures must not leave remote candidates"
+        );
+    }
+
     #[tokio::test]
     #[serial_test::serial]
     async fn opaque_remote_version_is_cleaned_before_parse_failure() {