[Automated Release] [Release] 2.0.0

Automated Notes:

This release is a major codebase optimization and bug fix release, focusing on performance improvements, code cleanup, and reliability fixes.

Breaking Changes

• Differ Package Removed: The go-bsdiff binary diffing library and all related code have been completely removed from the project.
  • The generator always used full-file replacement (os.ReadFile) - the bsdiff path was never triggered.
  • This removes github.com/gabstv/go-bsdiff and its indirect dependency on github.com/dsnet/compress from the dependency tree.
  • The Differ field has been removed from both the Generator and Applier structs.

New Features

• Magic-Byte Compression Detection: The patch applier now detects compression format from the first 4 bytes of the patch file ({ = JSON, \x28\xB5\x2F\xFD = zstd, \x1F\x8B = gzip) instead of trying each decompressor in sequence until one succeeds. This eliminates wasted decode attempts and speeds up patch loading.

• Streaming Patch Loading: LoadPatch() has been rewritten to use streaming file I/O instead of reading the entire patch file into memory. Large patches are now processed with constant memory usage proportional to the decompressed JSON, not the compressed file size.

Enhancements & Improvements

• Multi-Part Splitting for Reverse Patches: The --crp (create reverse patch) flag now correctly respects the --splitsize option. Previously, reverse patches were never split regardless of size.

• Compression Level Passthrough: SavePatch() now accepts a compression level parameter instead of hardcoding level 3. The --level flag is now fully respected for all patch types, including multi-part patches.

• Redundant SHA-256 Removed: The generator no longer re-computes SHA-256 checksums on every changed file - the scanner already computed these into the manifest. This saves approximately 12-20 seconds per 10GB of changed data.

• Improved Buffer Sizing: Buffered reader sizes reduced from 64MB to 64KB for streaming JSON decoding. The 64MB buffers provided no throughput benefit for the streaming decoder while consuming excessive memory.

• Deduplicated Key File Detection: The detectKeyFile() helper replaced 6 copy-pasted instances of the program.exe/game.exe/app.exe/main.exe detection loop across all three generation modes.

• Encoder Deduplication: generator/main.go now delegates to utils.SavePatch() instead of duplicating the entire streaming JSON pipeline. This removed approximately 210 lines of duplicated encoding functions and 4 unused imports.

Bug Fixes

• Same-Name Directory Crash Fixed: Using --from-dir and --to-dir with identical folder names (e.g., both pointing to a folder named "MyApp") no longer crashes with a "version is already registered" error.

• Reverse Filename Collision Fixed: When generating reverse patches with --crp from same-named directories, the reverse patch now uses a _rev suffix (e.g., App-to-App_rev.patch) instead of overwriting the forward patch file.

• Executable Creation with Multi-Part Patches Fixed: Creating self-contained executables with --create-exe no longer fails with "file not found" when --splitsize causes the patch to be split into multiple parts. The system now correctly locates the .01.patch file.

Housekeeping & Refactoring

• Removed Dead Code: Removed the unused VerifyAfter field from PatchOptions, cleaned up ~20 lines of nonsensical dead code in multipart.go, and removed unused Config fields (PreservePerms, VerifySignatures, SigningKeyPath).

• Documentation Updated: Architecture diagrams and component descriptions updated to reflect the removed differ package and current code structure. Data structures documentation corrected to match actual code behavior.

• Expanded Test Suite: Added 8 new optimization tests (tests 61-68) to advanced-test.ps1 covering key file detection, compression level passthrough, streaming LoadPatch, and reverse patch roundtrip verification.