refactor: remove dead SparseWriter decorator

crates/engine/README.md

@@ -16,7 +16,7 @@ drive file operations through this crate.
 - `apply_delta` / `generate_delta` / `generate_file_signature` - end-to-end delta helpers
 - `SignatureLayout` / `calculate_signature_layout` - upstream-compatible block-size heuristics
 - `LocalCopyPlan` - recursive wire-compatible local transfer executor
-- `SparseWriter` / `SparseReader` / `SparseDetector` - sparse file I/O with zero-run detection
+- `SparseReader` / `SparseDetector` - sparse file I/O with zero-run detection
 - `BufferPool` / `PooledBuffer` - RAII buffer reuse to eliminate per-file heap churn
 - `FuzzyMatcher` - basis-file similarity scoring for `--fuzzy`
 - `DeleteTiming` - controls before/after deletion passes

crates/engine/src/lib.rs

@@ -30,8 +30,8 @@
 //! [`local_copy::LocalCopyPlan`] drives recursive, wire-compatible local
 //! transfers (regular files, directories, symbolic links, FIFOs). Key features:
 //! - Temp-file write + atomic rename (`--inplace` bypasses the rename).
-//! - Sparse file support via [`SparseWriter`] / [`SparseReader`] / [`SparseDetector`]
-//!   with 16-byte `u128` zero-run detection and a single seek-per-zero-run invariant.
+//! - Sparse file support via [`SparseReader`] / [`SparseDetector`] with 16-byte
+//!   `u128` zero-run detection and a single seek-per-zero-run invariant.
 //! - Deletion passes controlled by [`DeleteTiming`] (before/after transfer).
 //! - Backup paths computed by [`compute_backup_path`].
 //! - Reference-directory comparisons via [`ReferenceDirectory`].
@@ -221,9 +221,8 @@ pub use local_copy::{
     LocalCopyError, LocalCopyErrorKind, LocalCopyOptions, LocalCopyOptionsBuilder, LocalCopyPlan,
     LocalCopySummary, ReferenceDirectory, ReferenceDirectoryKind, SkipCompressList,
     SkipCompressParseError, SparseDetectStrategy, SparseDetector, SparseReader, SparseRegion,
-    SparseWriteStats, SparseWriter, ZeroScanStrategy, compute_backup_path, trace_make_backup_copy,
-    trace_make_backup_device, trace_make_backup_hlink, trace_make_backup_rename,
-    trace_make_backup_symlink,
+    compute_backup_path, trace_make_backup_copy, trace_make_backup_device, trace_make_backup_hlink,
+    trace_make_backup_rename, trace_make_backup_symlink,
 };
 
 /// File signature generation for delta transfers.

crates/engine/src/local_copy/executor/file/mod.rs

@@ -36,8 +36,5 @@ pub(crate) use paths::partial_destination_path;
 pub(crate) use paths::temp_name_with_suffix;
 #[cfg(test)]
 pub(crate) use preallocate::maybe_preallocate_destination;
-pub use sparse::{
-    SparseDetectStrategy, SparseDetector, SparseReader, SparseRegion, SparseWriteStats,
-    SparseWriter, ZeroScanStrategy,
-};
+pub use sparse::{SparseDetectStrategy, SparseDetector, SparseReader, SparseRegion};
 pub(crate) use sparse::{SparseWriteState, write_sparse_chunk};

crates/engine/src/local_copy/executor/file/sparse/mod.rs

@@ -11,14 +11,12 @@ mod detect;
 mod hole_punch;
 mod reader;
 mod state;
-mod writer;
 
 #[cfg(test)]
 mod tests;
 
 pub use detect::SparseDetector;
 pub use reader::SparseReader;
-pub use writer::{SparseWriteStats, SparseWriter, ZeroScanStrategy};
 
 /// Selects the mechanism used by [`SparseReader::detect_holes`] to identify
 /// sparse regions in a file.