> ## Documentation Index
> Fetch the complete documentation index at: https://docs.crust.moumen.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Support and non-goals

> What is supported, what will never be built, and what to expect from maintenance.

## Supported

|                  |                       |
| ---------------- | --------------------- |
| Next.js          | 15 and 16, App Router |
| Bundlers         | webpack and Turbopack |
| Node             | 20+                   |
| Package managers | pnpm, npm, yarn, bun  |

Two Next majors, both bundlers. Outside that range crust **refuses to run** rather than emit output
derived from artifacts whose shape has not been verified.

<Note>
  Manifest shapes and artifact locations are undocumented and move on minor releases. A nightly CI job
  runs the fixtures against `next@canary`, so breakage surfaces before an issue does.
</Note>

## Non-goals

These are permanent. They were written down before the first user arrived, because saying no in
month three is only easy if you said it in month zero.

<AccordionGroup>
  <Accordion title="Not a runtime APM">
    No error tracking, no distributed tracing, no alerting. The optional
    [span aggregator](/docs/guides/staging#server-spans) groups render time by route and stops there.
  </Accordion>

  <Accordion title="Not a Lighthouse or PageSpeed replacement">
    crust measures what your build produced and what your users' browsers reported. It does not
    produce a score.
  </Accordion>

  <Accordion title="Not multi-framework">
    Next.js App Router only. A Pages Router app gets a clear refusal; a hybrid app gets its `app/`
    routes analysed with a warning that `pages/` is invisible to every number.
  </Accordion>

  <Accordion title="Not a hosted service">
    No accounts, no SaaS dashboard. Snapshots live in your repository.
  </Accordion>

  <Accordion title="Not a bundler">
    It reads build output. It never changes how your app builds in production.
  </Accordion>

  <Accordion title="No config file">
    Until three separate people request the same option. Zero-config is a feature, and config
    surface is permanent API you cannot remove. The two JSON escape hatches in
    [`.perf/`](/docs/reference/files) are data, not configuration.
  </Accordion>
</AccordionGroup>

## Known limits

* **Per-file attribution needs `productionBrowserSourceMaps`.** Without it, route totals and shell
  analysis still work; attribution reports itself unavailable.
* **Taint propagation is module-level**, not function-level. It errs toward reporting dynamism.
* **The stamping transform is not built.** Component-level runtime attribution would need it;
  source maps cover file-level attribution instead, and measure better on Turbopack than webpack.
* **Server components rendered from props or `children`** are reported as
  [unknown](/docs/concepts/unknowns) rather than guessed at.

## Maintenance

MIT. Supports Next 15–16, best-effort, issues triaged weekly. That is the commitment - stating it
plainly is more useful than an implied promise nobody wrote down.