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# Layout module instructions
Scoped guidance for `layout/`. The global `../AGENTS.md` still applies.
## Start here
Read the docs in `layout/docs/` before non-trivial work.
- `layout/docs/LayoutOverview.md` for frame tree, frame construction, reflow,
and fragmentation.
## Review
- Read `layout/docs/LayoutCodeReviewerChecklist.md` as guidance when reviewing
layout changes.
## Testing
- When adding reftests / crashtests for standardized CSS properties, prefer
putting them in the relevant subdirectory of
`testing/web-platform/tests/css/` rather than the in-tree `layout/reftests/`
or the per-subdirectory `layout/*/crashtests/` directories.
## Debugging
- Layout debugger can dump useful layout internal information for a URL. Run
`./mach run --layoutdebug [filename]`. Read `layout/docs/LayoutDebugger.md`
for usage.