Aider
Type: full-code · Vendor: Paul Gauthier / Aider-AI community · Language: Python · License: Apache-2.0 · Status: active · Status in practice: mature · First released: 2023-05-09
Open-source terminal-native AI pair-programmer that edits files in a git repo through diff-formatted edits, auto-commits each change, and works with almost any LLM provider.
Description. Aider runs in the terminal, takes natural-language requests, and applies them as diffs to files in your git repo. Every edit is auto-committed with a descriptive message so you can review via standard git tools and use /undo to roll back. A concise repo map of classes/functions is sent with each request so the model has whole-codebase awareness. Aider supports cloud and local models, prompt caching on supported providers, voice input, image input, automatic lint+test loops, and an 'architect' mode that splits planning from editing across two models.
Agent loop shape. Single-agent loop built around git as substrate. User types a request → Aider consults the repo-map → selects an edit format (whole-file, diff, udiff, search-replace) appropriate to the model → emits edits → applies them to files → optionally runs --lint-cmd and --test-cmd → tries to fix any non-zero exit → commits to git. /undo rewinds the last commit. Architect mode runs a planning model first, then hands the proposal to a faster editor model.
Primary use cases
- terminal-native AI pair-programming in a git repo
- diff-formatted edits with auto-commit and /undo
- architect+editor multi-model splits
- auto-lint and auto-test feedback loops
Key concepts
- Edit formats (docs) — Model emits diffs (whole-file / diff / udiff / search-replace) Aider parses and applies.
- Repo-map → agentic-rag (docs) — Graph-optimised concise map of the whole repo sent to the LLM.
- Git as memory → replay-time-travel (docs) — Every edit is a commit; /undo is git revert.
- Modes (code/ask/architect/help) → multi-model-routing (docs) — Architect+editor split is the multi-model loop.
- Prompt caching → prompt-caching (docs) — Caches system prompt, read-only files, repo map, editable files.
- Auto lint + auto test → code-execution (docs) — Automatic feedback loop after every edit.
Patterns this full-code implements —
- ★Agent-Computer Interface
Terminal-native ACI; also IDE-aware via comment-driven prompts.
- ★Code-as-Action Agent
Edits are the action; every edit auto-commits to git.
- ★★Code Execution
Auto-lint + auto-test feedback loop; non-zero exits drive retry.
- ★★Multi-Model Routing
/model switches in-chat; architect+editor mode is a two-model split.
- ★★Prompt Caching
Caches system prompt, read-only files, repo map, editable files.
- ★★Replay / Time-Travel
/undo rewinds the last commit; standard git tools work.
- ★★Agentic RAG
Repo-map is graph-based retrieval (not vector RAG); concise map of classes/functions sent with each request.
- ★★Plan-and-Execute
Architect+editor split is a one-step plan, not multi-step plan-and-execute.
- ★★ReAct
Honest downgrade — Aider's loop is respond+apply+optionally retry on lint/test feedback, not a full ReAct trace; no upstream text names ReAct.
- ★★Step Budget
Soft token-budget knob (--max-chat-history-tokens) triggers summarization; --map-tokens caps repo-map size. No documented step-count cap, so honest 'limited'.
- ★★Tool Use
Aider predates modern tool-calling — its tools are slash commands the user/model invoke: /run, /test, /commit, /undo, /add — not LLM tool-calls.
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- Verification status: verified