[MissingType] Room + @Parcelize entity fails KSP resolution under AGP 9 built-in Kotlin (still fails on 2.3.10)

[gailroco]

Kotlin version: 2.2.21
KSP version: tested 2.3.1 and 2.3.10 (same failure on both)
AGP version: 9.3.0, built-in Kotlin enabled (android.builtInKotlin default, android.newDsl default — i.e. not opted out)
Gradle version: 9.5.0
Room version: 2.8.4 (androidx.room:room-compiler via ksp)

Describe the bug

Under AGP 9's built-in Kotlin, KSP's type resolution fails for a Room
@Entity class that also carries kotlin-parcelize's @Parcelize. Room's
KSP processor aborts with [MissingType], and the same class compiles and
processes fine as soon as @Parcelize/Parcelable is removed — with
everything else (KSP version, AGP version, built-in Kotlin enabled) held
identical.

This is not the R-class resolution bug fixed in 2.3.10 (#2857) — I upgraded
from 2.3.1 to 2.3.10 specifically expecting that fix to cover this, and hit
the identical failure on both.

Repro

plugins block (module-level):

plugins {
    id 'com.android.application'
    id 'com.google.devtools.ksp'
    id 'androidx.room'
    id 'kotlin-parcelize'
    // no org.jetbrains.kotlin.android — using AGP's built-in Kotlin
}

Entity:

import android.os.Parcelable
import androidx.room.Entity
import androidx.room.PrimaryKey
import kotlinx.parcelize.Parcelize

@Parcelize
@Entity(tableName = "songs")
data class Song(
    @PrimaryKey val id: String,
    val title: String,
    // ...more fields, all Room-supported primitive/String/nullable types
) : Parcelable

Running kspDebugKotlin fails:

e: [ksp] .../Song.kt:16: [MissingType]: Element 'com.example.Song' references a type that is not present
e: [ksp] androidx.room.RoomKspProcessor was unable to process 'com.example.MusicDatabase' because not all of its dependencies could be resolved. Check for compilation errors or a circular dependency with generated code.

> Task :app:kspDebugKotlin FAILED
> A failure occurred while executing com.google.devtools.ksp.gradle.KspAAWorkerAction
   > KSP failed with exit code: PROCESSING_ERROR

Removing @Parcelize/: Parcelable from Song (nothing else changed —
same KSP version, same AGP version, built-in Kotlin still enabled) makes
kspDebugKotlin succeed immediately.

With org.jetbrains.kotlin.android applied instead of built-in Kotlin
(i.e. android.builtInKotlin=false, android.newDsl=false), the same
@Parcelize + @Entity class processes without error on the same KSP
version. So this reproduces only with built-in Kotlin enabled.

Expected behavior

KSP should be able to resolve a class annotated with both @Entity and
@Parcelize under built-in Kotlin, the same way it does under the classic
org.jetbrains.kotlin.android plugin.

Additional context

This is currently the only thing blocking a project of mine from dropping
the android.builtInKotlin/android.newDsl opt-out flags (AGP 10 removes
the ability to opt out entirely, so this needs to resolve before that
upgrade is possible). Happy to provide a minimal standalone reproduction
project if useful.