handle version in cli

CHANGELOG.md

@@ -7,6 +7,30 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+- **New CLI Command**: `deltaglider migrate` for S3-to-S3 bucket migration with compression
+  - Supports resume capability (skips already migrated files)
+  - Real-time progress tracking with file count and statistics
+  - Interactive confirmation prompt (use `--yes` to skip)
+  - Prefix preservation by default (use `--no-preserve-prefix` to disable)
+  - Dry run mode with `--dry-run` flag
+  - Include/exclude pattern filtering
+  - Shows compression statistics after migration
+- **S3-to-S3 Recursive Copy**: `deltaglider cp -r s3://source/ s3://dest/` now supported
+  - Automatically uses migration functionality with prefix preservation
+  - Applies delta compression during transfer
+- **Version Command**: Added `--version` flag to show deltaglider version
+  - Usage: `deltaglider --version`
+
+### Changed
+- Recursive S3-to-S3 copy operations now preserve source prefix structure by default
+- Migration operations show formatted output with source and destination paths
+
+### Documentation
+- Added comprehensive migration guide in README.md
+- Updated CLI reference with migrate command examples
+- Added prefix preservation behavior documentation
+
 ## [5.1.1] - 2025-01-10
 
 ### Fixed

src/deltaglider/app/cli/main.py

@@ -10,6 +10,7 @@ from pathlib import Path
 
 import click
 
+from ... import __version__
 from ...adapters import (
     NoopMetricsAdapter,
     S3StorageAdapter,
@@ -113,8 +114,16 @@ def create_service(
     )
 
 
+def _version_callback(ctx: click.Context, param: click.Parameter, value: bool) -> None:
+    """Callback for --version option."""
+    if value:
+        click.echo(f"deltaglider {__version__}")
+        ctx.exit(0)
+
+
 @click.group()
 @click.option("--debug", is_flag=True, help="Enable debug logging")
+@click.option("--version", is_flag=True, is_eager=True, expose_value=False, callback=_version_callback, help="Show version and exit")
 @click.pass_context
 def cli(ctx: click.Context, debug: bool) -> None:
     """DeltaGlider - Delta-aware S3 file storage wrapper."""