A modern programming language that makes developers happier.

kotlinlang

Have a look at <https://cs.android.com/androidx/platform/frameworks/support/+/androidx-main:compose/runtime/runtime/src/commonMain/kotlin/androidx/compose/runtime/Composer.kt;l=299;bpv=1;bpt=1?q=composer|Composer> and <https://cs.android.com/androidx/platform/frameworks/support/+/androidx-main:compose/runtime/runtime/src/commonMain/kotlin/androidx/compose/runtime/Applier.kt;drc=c371181118e53eafa2cad21c2758ab3412dc7b7e;bpv=1;bpt=1;l=35|Applier>.

also if you are really interested in the internals, check out <https://jorgecastillo.dev/book/>

Where are you reading the source code?
If you are reading in an IDE or on <http://cs.android.com|cs.android.com>, you can easily follow the call hierarchy and find <https://cs.android.com/androidx/platform/frameworks/support/+/androidx-main:compose/runtime/runtime/src/commonMain/kotlin/androidx/compose/runtime/Recomposer.kt;drc=e81899ee585297dca9ed14c5d192ab0642208a23;l=1533|this>, which is where state reads and writes during composition are recorded.
And <https://cs.android.com/androidx/platform/frameworks/support/+/androidx-main:compose/runtime/runtime/src/commonMain/kotlin/androidx/compose/runtime/Recomposer.kt;drc=e81899ee585297dca9ed14c5d192ab0642208a23;l=1142|here> is what happens when states are written outside composition.

Please follow the call hierarchy yourself. Another way is to set a breakpoint on the lines and debug the app.