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Aider vs Bernstein
Aider is the original open-source coding agent. Talks to ~50 LLM providers via LiteLLM, commits each change to git automatically, ships a repo-map for context. Apache-2.0, 30k+ stars.
Last verified against aider-chat 0.86.x on 2026-05-05.
Install both
Aider
pip install aider-chatBernstein
pipx install bernsteinApache-2.0 · 42 adapters · Python scheduler · zero LLM tokens spent on coordination.
Feature matrix
| Capability | Aider | Bernstein |
|---|---|---|
| License | Apache-2.0 | Apache-2.0 |
| Authentication | Provider API key (anthropic / openai / openrouter / etc.) | Per-agent credential scoping (no global key) |
| Parallel-safe in worktrees | Yes | Yes (designed around git worktrees) |
| MCP support | No | Yes (MCP server + tool injection) |
| HMAC-chained audit log | No | Yes (RFC 2104 SHA-256 chain in .sdd/) |
| Coordinator is an LLM | — | No — deterministic Python scheduler |
| Multi-agent orchestration | One agent in a terminal | Aider + 41 other adapters in parallel |
Source: src/bernstein/adapters/aider.py · upstream
When to choose which
Choose Aider
If you already use Aider and like its `/add`, `/run`, `/test` muscle memory — Bernstein doesn't replace any of that. Aider is also the right tool when MCP is overkill: many tasks are one repo, one agent, one provider, and Aider's surface is smaller and faster than anything wrapping it.
Choose Bernstein
When you want Aider's reliability AND parallelism. Bernstein spawns 3-8 Aiders in separate worktrees against the same goal, each scoped to a different sub-task, and reconciles the diffs. The audit chain on top of Aider's per-change commits is also a regulatory differentiator the bare CLI doesn't have.
FAQ
Does Bernstein replace Aider?
No. Bernstein wraps Aider as one of 42 adapters and routes tasks to it based on a per-task pass-rate history. Aider keeps doing what it does well; the orchestrator decides when it gets the work.
What does the audit chain give me that Aider can't?
An HMAC-SHA256 row chain over every routing decision and every quality-gate result, written under .sdd/. Deleting or rewriting a row breaks the chain and the verifier rejects the file on next read. Useful for compliance reviews where the regulator wants to replay the run.
Can I run Aider alongside Claude Code, Codex, and Aider in the same session?
Yes. That's the design point. Each agent runs in its own git worktree, so file edits never collide. Bernstein merges results back to the branch only after the configured quality gates pass.