Reorganize brain: projects/ top level, rename filenames, update homepage

- Moved everything from ideas/passepartout/ to projects/passepartout/
- Moved legal structures to projects/flags/
- Created missing _index.org files for all subdirectories
- Stripped redundant passepartout- prefix from filenames
- Rewrote root _index.org as generalized brain index (projects + concepts)
- Updated Hugo nav to Projects/Concepts
- Updated build script section descriptions
- Deleted stale ideas/passepartout-economics.md orphan

projects/passepartout/strategy/competitors/ai-agents-scoping/aider.org

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+:PROPERTIES:
+:ID:       c3aab2e8-7e43-4abc-93f0-741675cfd78c
+:CREATED:  [2026-05-22 Thu]
+:END:
+#+title: Aider — AI Coding Agent
+#+filetags: :passepartout:strategy:competitive:aider:
+
+Language: Python. ~6.8M pip installs. ~40K lines. MIT license. The oldest and most mature open-source coding agent.
+
+Architecture: Chat-based Coder class with 5 edit formats (diff, udiff, patch, whole, architect). Uses litellm for universal provider access (50+ providers). RepoMap provides codebase awareness via cosine-similarity embedding.
+
+Safety model: Purely prompt-based plus user-confirmation dialogs. No deterministic gate stack. No sandboxing. No model output validator. The allowed_to_edit() gate is a single user confirmation call. --yes flag auto-approves. Aider can edit its own source code with no special protection — self-modification is undetectable.
+
+Data model: Ad-hoc. Chat messages in memory. Git commits for persistence. RepoMap is a cosine-similarity index. No persistent memory across sessions. No knowledge graph.
+
+Self-modification: Full. No guard against editing its own files.
+
+Verification: None.
+
+Key gap vs Passepartout: No safety gates, no persistent memory model, no knowledge representation, no verification, no self-modification protection, no architecture for neurosymbolic reasoning. It is a thin shell around litellm + edit format parsers.
+
+See the full [[id:3aa22300-2f25-57b0-8787-9f199cc978b1][competitive analysis]] for the landscape view and comparison.