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/codex-cli.org

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+:PROPERTIES:
+:ID:       e929ff32-28d8-4a29-bf74-d55babc040d1
+:CREATED:  [2026-05-22 Thu]
+:END:
+#+title: Codex CLI — OpenAI AI Coding Agent
+#+filetags: :passepartout:strategy:competitive:codex:
+
+OpenAI's open-source coding agent. Rust, ~950K lines, sandboxed.
+
+Architecture: ~116 crate Rust workspace with a protocol layer (SQ/EQ session types), sandbox manager (macOS Seatbelt, Linux nsjail), multi-provider support, configurable TUI.
+
+Safety model: Most sophisticated safety system of any coding agent analyzed. Multi-layer: process hardening (macOS Seatbelt with 4 profile tiers), execution policy engine, sandboxing via nsjail/Seatbelt, Guardian module for tool permission gating. No prompt-based safety — all deterministic through policy definitions.
+
+Data model: Protocol-defined session types. Structured request/response models. Config through TOML files with schema validation.
+
+Self-modification: Protected by sandbox — the agent cannot escape to modify its own binary or config without explicit policy override.
+
+Verification: None (no proof system).
+
+Key gap vs Passepartout: No knowledge graph, no persistent memory model, no deterministic gate stack for agent behavior (only OS-level sandboxing), no ACL2/prover, no neurosymbolic architecture. Strongest sandbox but weakest cognitive architecture.
+
+See the full [[id:3aa22300-2f25-57b0-8787-9f199cc978b1][competitive analysis]] for the landscape view and comparison.