AGENTS.kmp.md — Kotlin Multiplatform shared code

Additive to ../AGENTS.md and AGENTS.kotlin.md. Applies to shared/ (or your KMP module).

Rules

• commonMain contains no platform APIs. If you reach for java.*, android.*, Foundation, or NSObject, you are in the wrong source set.
• expect/actual pairs land together, in the same PR, with both platform implementations. Never merge an expect with one actual.
• Serialization is kotlinx.serialization with explicit @SerialName on every field that crosses the wire. Do not rely on property names — a rename becomes a production bug.
• Public shared API is designed for both callers: no Kotlin-only constructs in signatures that Swift will consume awkwardly (default args, sealed hierarchies without a mapped enum, suspend functions without a callback wrapper where needed).
• Any change to shared model shapes is a Kitchen change: two platforms and a server contract are downstream.

Check

./gradlew :shared:allTests
./gradlew :shared:linkDebugFrameworkIosSimulatorArm64   # catches Swift-facing breakage early