# Calepin runtime split
The embedded Typst runtime (`RUNTIME_SOURCE` in `runtime.rs`, written to
`.calepin/calepin.typ`) is concatenated from six focused files in this order.
Typst resolves symbols top to bottom, so each file may only reference symbols
defined in itself or an earlier file:
1. `runtime/template.typ`
- HTML shell helper (`html`) for the final document wrapper
2. `runtime/themes.typ`
- Syntax-highlighting themes for the input/output code blocks
(`_input-syntax-theme`, `_output-syntax-theme`)
3. `runtime/state.typ`
- The mode constant, label counters, and the option-defaults dictionaries
- Small pure helpers (raw-node parsing, MIME selection, asset/href resolution,
label attachment)
4. `runtime/render.typ`
- Styled input/output code blocks (`_input-block`, `_output-block`, `_raw-block`)
- CSS/HTML figure helpers and the result-dispatch chain
(`_render-results` -> `_render-item` -> `_render-display-item`)
5. `runtime/options.typ`
- `setup()` plus full option resolution (`_setup-options`, `_resolve-options`)
6. `runtime/chunk.typ`
- Public chunking API (`chunk`, `inline`, `chunk-from-raw-plain`)
- Query/render dispatch (`_emit-chunk`), label handling, raw-block interception
`runtime.rs` writes `.calepin/calepin.typ` from:
```rust
include_str!("runtime/template.typ") +
include_str!("runtime/themes.typ") +
include_str!("runtime/state.typ") +
include_str!("runtime/render.typ") +
include_str!("runtime/options.typ") +
include_str!("runtime/chunk.typ")
```