Draw the native call in the app

A wrapper around the logged-in content rather than an overlay, because a minimized call takes a strip of height above it while a maximized one covers it.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

features/callnative/api/build.gradle.kts

@@ -6,7 +6,8 @@
  */
 
 plugins {
-    id("io.element.android-library")
+    // NativeCallHost renders the call, so this module carries a composable.
+    id("io.element.android-compose-library")
 }
 
 android {

features/callnative/api/src/main/kotlin/io/element/android/features/callnative/api/NativeCallHost.kt

@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) 2026 Element Creations Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+package io.element.android.features.callnative.api
+
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Modifier
+
+/**
+ * Where a native call is drawn, wrapped around the logged-in content.
+ *
+ * A wrapper rather than an overlay, because the two states of a call need different things from the
+ * layout: minimized, the call takes a strip of height above the content; maximized, it covers it. The
+ * [Modifier] handed back to [content] has consumed whatever window insets the call has already taken,
+ * so the screens underneath do not pad for the status bar a second time.
+ *
+ * With no call running this renders [content] and nothing else.
+ */
+interface NativeCallHost {
+    @Composable
+    fun Render(modifier: Modifier, content: @Composable (Modifier) -> Unit)
+}

features/callnative/api/src/main/kotlin/io/element/android/features/callnative/api/NativeCallPip.kt

@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) 2026 Element Creations Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+package io.element.android.features.callnative.api
+
+import android.app.Activity
+
+/**
+ * The one part of picture-in-picture that an Activity has to do itself.
+ *
+ * Everything else is installed where the call is drawn, which is inside the logged-in content and so
+ * knows which session's call it is. This does not: `onUserLeaveHint` is an Activity override, there is
+ * no session in scope at that point, and it applies to whichever call happens to be running.
+ *
+ * Only Android 11 and below reach this. From Android 12 the system is told up front that the Activity
+ * would like to shrink, which covers every way out of the app including the home gesture - the one
+ * people actually use, and the one this hook never sees.
+ */
+interface NativeCallPip {
+    /** Call from the host Activity's `onUserLeaveHint()` override. */
+    fun onUserLeaveHint(activity: Activity)
+}