---
title: proa chunks
description: Inspect static runs and dynamic slots.
---

`proa chunks` estimates how `html!`, `html_sync!`, `xml!`, and `xml_sync!` macro bodies split into consolidated static byte runs and dynamic slots. Use it when tuning hot SSR routes or reviewing a template that changed unexpectedly.

A leading `<?xml version="1.0" encoding="UTF-8"?>` declaration joins the adjacent static markup; it does not add a dynamic slot.

```bash
proa chunks src/pages/home.rs
proa chunks src/components
proa chunks --json src/pages/home.rs
```

## Report Fields

| Field | Meaning |
|-------|---------|
| `runs` | Number of consolidated static byte runs. |
| `static_bytes` | Estimated bytes across all static runs. |
| `largest_run` | Estimated size of the largest static run. |
| `text_slots` | Dynamic child/text slots such as `{child}`. |
| `attr_slots` | Dynamic attribute slots such as `class={classes}`. |

Dynamic text and attribute slots create run boundaries. Fewer, larger static runs generally render faster because more bytes can be copied as consolidated static segments.

## Example

```bash
proa chunks src/pages/home.rs
```

Text output includes one row per discovered macro body:

```text
macro (file:line)                                runs       static      largest  txt{} attr{}
src/pages/home.rs:18 html_sync!                     4         420B         180B      1      2
```

Use `--json` when feeding the output to scripts or dashboards.

## Changed Files

`chunks` uses the same Git file-selection flags as `lint` and `check`:

```bash
proa chunks --changed --base origin/main
proa chunks --staged --json
```

The report scans HTML and XML macros in Rust files. Markdown and unrelated macro dialects are not included.

## How To Use The Numbers

- Treat byte counts as estimates, not exact macro expansion output.
- Look for templates where small dynamic expressions split large static regions.
- Hoist invariant text and attribute values into literals where practical.
- Keep correctness first when deciding whether to reduce dynamic slots.