Multi-Dimensional Merge Agent

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a merge conflict resolver that uses program analysis techniques from recent academic research to automatically resolve git merge conflicts.

How it works

The engine applies a pipeline of increasingly sophisticated strategies:

Pattern-based DSL rules — Matches common conflict patterns (whitespace-only, identical changes, import unions, adjacent edits) and resolves them instantly with high confidence. Based on Svyatkovskiy et al., ICSE 2021.
Structured merge via tree-sitter CSTs — Parses code into concrete syntax trees and performs three-way tree amalgamation, eliminating false conflicts from formatting changes or reordering. Based on LASTMERGE, arXiv 2025.
Version Space Algebra (VSA) — For remaining conflicts, builds a compact representation of all possible resolutions by combining edits from both sides, then enumerates and ranks candidates. Based on Zhu & He, OOPSLA 2018.
Search-based resolution — Uses evolutionary search (genetic algorithm) over candidate resolutions, scored by a fitness function measuring token-level similarity to both parents. Based on Campos Junior et al., ACM TOSEM 2025.

Supported languages

Tree-sitter-based structured merge: Rust, JavaScript, TypeScript, Python, Java, Go, C, C++, Kotlin, TOML, YAML

Pattern-based and search-based strategies work on any text content.

Installation

cargo install merge-engine

Or build from source:

git clone https://github.com/maceip/merge-engine.git

cd merge-engine

cargo build --release

Usage

As a git custom merge driver

Add to your .gitconfig:

[merge "merge-engine"]
    name = merge-engine structured merge driver

    driver = merge-engine %O %A %B %P

Add to .gitattributes in your repo:

*.rs merge=merge-engine

*.kt merge=merge-engine

*.ts merge=merge-engine

*.py merge=merge-engine

CLI

# Resolve conflict from three files

merge-engine base.rs left.rs right.rs path.rs


# Dry-run: report conflicts without modifying files

merge-engine --check base.rs left.rs right.rs


# Read conflict markers from stdin

cat conflicted_file.rs | merge-engine --stdin

As a library

use merge_engine::{Resolver, ResolverConfig, Language};

let config = ResolverConfig {
    language: Some(Language::Rust),
    ..Default::default()
};
let resolver = Resolver::new(config);

let result = resolver.resolve_file(
    "fn main() { println!(\"hello\"); }",
    "fn main() { println!(\"hello world\"); }",
    "fn main() { println!(\"hello\"); eprintln!(\"debug\"); }",
);

println!("All resolved: {}", result.all_resolved);
println!("Merged:\n{}", result.merged_content);

Architecture

src/
├── lib.rs           Module exports + public API re-exports
├── main.rs          CLI binary (git merge driver)
├── types.rs         Core types: CstNode, MergeResult, Language, Confidence
├── resolver.rs      Main orchestrator — 4-stage pipeline
├── diff3.rs         Baseline 3-way text merge
├── parser.rs        Tree-sitter CST parsing
├── patterns.rs      7 DSL pattern rules
├── matcher.rs       Yang + Hungarian matching algorithms
├── amalgamator.rs   3-way tree merge
├── vsa.rs           Version Space Algebra
└── search.rs        Search-based resolution

License

MIT

merge-engine 0.1.0