# engineering/

```
Type: knowledge
```
Current-state facts about the codebase: crate layout, the sim/frontend
split and the invariants that protect it, determinism guardrails, the
save format, and the flow substrate (the shared engine under
signals/messages/money). `Type: knowledge` pages — edited in place, no
status field; a stale one is a bug, fixed in the commit that made it
stale.