Add soft-keyboard visibility signal for Android NativeActivity

[kevincarlson]

Summary

Closes the gap where a NativeActivity on Android never receives notification when the user dismisses or re-summons the soft keyboard (via back button, swipe-down gesture, or the keyboard's hide key). This leaves the bottom safe area reserved for a keyboard that is gone, and stales the ime_active mirror so the next caret tap needlessly re-summons an already-visible keyboard.

The fix installs a real Android inset callback (ImeInsetsListener, a Java shim) on the decor view that fires on every IME visibility transition, reads WindowInsets.Type.ime() visibility (API 30+), and bridges the signal back to the Rust event loop via JNI. The event loop then re-queries the safe area and re-syncs ime_active, reusing the existing IME-settle path so the bottom padding converges to the settled keyboard height (0 on a collapse).

Key Changes

• New Java shim (patches/loki-file-access/android/ImeInsetsListener.java): Implements View.OnApplyWindowInsetsListener to observe decor-view inset changes and call back into native code on every IME visibility transition (API 30+, no-op below).

• New JNI module (patches/loki-file-access/src/platform/android/jni_ime.rs):

  • install_ime_listener(activity_ptr) — loads the shim through the application class loader (native threads see only framework classes), binds the native callback via RegisterNatives (independent of host .so name), and installs the listener on the UI thread.
  • set_ime_visibility_listener(callback) — registers the closure invoked on every visibility change.
  • ime_insets_changed — JNI callback that fires on the Android UI thread and invokes the registered closure.

• New blitz-shell bridge (patches/blitz-shell/src/ime_android.rs):

  • notify_ime_visibility_changed(visible) — called from JNI, records the new visibility and wakes the event loop with a Poll.
  • take_pending() — drained in WindowState::poll, returns the pending visibility change.
  • register(proxy, window_id) — called during window init to record the event-loop target.

• Integration in blitz-shell (patches/blitz-shell/src/window.rs):

  • Register the IME bridge during View::init.
  • Drain pending visibility changes in poll(), mirror into ime_active, and call arm_ime_settle() to re-query the safe area across the keyboard animation.

• Integration in loki-text (loki-text/src/lib.rs):

  • Register the visibility callback before installing the listener so the first callback is not dropped.
  • Wire loki_file_access::set_ime_visibility_listener to blitz_shell::notify_ime_visibility_changed.

• Build system updates (build.rs, build-android.sh, build-android.ps1, build-aab.sh):

  • Generalized to compile both FilePickerActivity.java and ImeInsetsListener.java into a single classes.dex.
  • Added collect_class_files() to handle inner classes (e.g., the anonymous Runnable in ImeInsetsListener).

• Minification config (android/app/build.gradle.kts): Updated comment to note that both shims are JNI-referenced and must not be minified.

• Documentation (docs/patches.md): Added detailed explanation of the user-driven soft-keyboard collapse signal, including the API 30+ requirement and the re-sync path.

Implementation Details

• The listener passes insets through (v.onApplyWindowInsets), so it does not consume or alter the system's inset handling.
• The shim is dexed alongside FilePickerActivity and, being JNI-referenced, requires minification to stay off (

https://claude.ai/code/session_01V9fnSNP4c5E9xNhG7T8jrf