Public: Aider (OSS pair programmer reference)

Architectural notes

Aider is fully open source, so its "stack" is well documented. It's a
CLI pair programmer that maintains a repo map, generates edits as
diffs, and commits to git automatically.

Notable architectural choices (from the project README and docs):
- Repo map as the primary retrieval mechanism (no embeddings by default).
- Edits emitted as unified diffs the user reviews per commit.
- Provider-agnostic via LiteLLM, including local models via Ollama.
- Public leaderboard ("polyglot" benchmark) for code-edit accuracy.

Useful as the canonical OSS reference for the coding-assistant category.