comparison
Lacy Shell vs Aider
A shell plugin that routes your input vs a coding assistant that edits your files.
The core difference
Aider is an AI pair programming tool. You run aider in a repo, have a conversation, and it edits files directly using git commits. Lacy is a shell plugin that detects whether you typed a command or a question and sends it to the right place. Aider writes code. Lacy routes input.
| Lacy Shell | Aider | |
|---|---|---|
| Type | ZSH/Bash plugin | AI coding assistant (CLI) |
| What it does | Routes input to shell or AI agent | Edits files through conversation |
| Invocation | Just type in your shell | Run aider to start a session |
| Integration | Lives in your shell prompt | Separate interactive session |
| AI backend | Any CLI (Claude, Gemini, OpenCode, etc.) | OpenAI, Anthropic, local models, 20+ providers |
| API key required | No (uses your installed CLI tool) | Yes |
| Edits files | No (the AI agent you connect can) | Yes, directly with git commits |
| Real-time indicator | Yes — green/magenta as you type | No |
| Shell commands | Run natively alongside AI queries | Run via /run inside Aider session |
| Open source | Yes, MIT | Yes, Apache 2.0 |
They solve different problems
Aider is for focused coding sessions. You open it in a repo, tell it what to build or fix, and it makes the changes. It has deep awareness of your codebase — repo map, file context, git history.
Lacy is for the rest of your terminal time. You’re running commands, checking logs, navigating directories, and occasionally you want to ask something. Instead of switching to a different tool, you just type the question and Lacy sends it to your agent.
If you type “refactor the auth module to use JWT” in Aider, it edits your source files. If you type it with Lacy, your connected agent handles it however that agent works. Aider owns the edit loop. Lacy owns the routing.
When to use Lacy
- You want AI inline with your normal shell workflow
- You already have a CLI agent you like and want seamless access
- You want commands and questions in one place, no context switching
- You don’t need direct file editing from the AI layer
When to use Aider
- You want AI to directly edit your code with full repo context
- You prefer pair-programming style conversations
- You want automatic git commits for every change
- You need deep codebase awareness (repo maps, file trees)
Can you use both?
Absolutely. Lacy recognizes aider as a valid command and lets it run in the shell. Use Lacy for day-to-day terminal work and quick questions. Open Aider when you need a focused coding session. They complement each other well — one routes, the other edits.
The bottom line
Aider is one of the best terminal-based AI coding tools available. It understands your codebase and makes changes with precision. But it runs as a separate session, not in your shell prompt.
Lacy doesn’t compete with Aider — it fills the gap between coding sessions. It makes your regular terminal AI-aware so you never have to decide whether to type a command or switch to a tool. If you use Aider for coding, Lacy gives your shell the same natural-language fluency everywhere else.
Further reading
- Why I didn’t use AI to classify AI input — how Lacy decides whether your input is a shell command or natural language, without ML.