From declaration to execution

A Cookfile is a declaration. Nothing in it runs until cook has lowered it to Lua, registered every unit, and built one graph from the declared ordering. This eighteen-second simulation shows the four stages on one small build.

The four stages

graph LR
  A[Cookfile] -->|lower| B[Lua]
  B -->|register| C[units]
  C -->|build| D[one DAG]
  D -->|execute| E{key in store?}
  E -- hit --> F[restore]
  E -- miss --> G[run, then store]

1. Lower. Every Cookfile becomes Lua before it runs. cook emit-lua shows you exactly what yours compiles to; see 10. Dropping into Lua.
2. Register. The Lua registers units: each has declared inputs, outputs, and the determinants you sealed into its key.
3. Build the graph. Edges come from declared ordering and from $<recipe> references (4. Connecting recipes). Independent nodes can run together.
4. Execute what is ready. Every ready unit checks the cache first. Only the misses reach the workers, and every miss has a printed cause (9. Caching and cache trust).