A coding agent that treats your API budget as a design constraint

What it does

Dirac is a coding agent (VS Code extension and CLI) that automates refactoring and code changes across large repos. It reads files, runs terminal commands, and edits code—batching multiple files into a single LLM roundtrip to keep latency and token counts low. The pitch is simple: smaller, better-curated context means the model reasons better and your bill shrinks.

The interesting bit

Instead of relying on brittle line-number references, Dirac uses hash-anchored edits to target code precisely, and it manipulates ASTs directly for structural changes like function extraction. It also deliberately ignores MCP and only uses models with native tool calling, which is either stubbornness or confidence depending on your stack.

Key highlights

• Claims a 64.8% average cost reduction versus competitors on public benchmark tasks, with an 8/8 success rate on the evaluated refactoring suite.
• Topped the Terminal-Bench-2 leaderboard with a 65.2% score using gemini-3-flash-preview, beating Google’s official baseline and the closed-source Junie CLI.
• Supports multi-file batching and language-aware AST manipulation for TypeScript, Python, C++, and others.
• Includes autonomous tool use (terminal, headless browser, file I/O) with an approval-based workflow.
• Reads project-specific instructions from AGENTS.md and existing Claude skill directories (.ai, .claude, .agents).

Caveats

• The cost comparison table notes a bug in Cline (the parent repo) that caused slight underreporting of cache-read costs for both Dirac and Cline; the authors submitted a fix but have not yet rerun the full evals.
• Node.js v25 is explicitly unsupported due to an upstream V8 Turboshaft compiler bug that crashes WASM initialization.
• MCP is not supported at all; you are limited to models that offer native tool calling.

Verdict

Worth a look if you are burning through API credits with other agents and want something that optimizes for token efficiency over feature bloat. Skip it if your workflow depends on MCP or you are running Node.js v25.