fix: 16 KB page-size RELRO compatibility

[ovitrif]

Context

Summary

Android 17 shows this compatibility warning when launching the dev build on Pixel 10 Pro:

This app isn't 16 KB-compatible. RELRO alignment check failed.

The APK is already built with 16 KB PT_LOAD alignment and passes APK zip alignment. The remaining failure is PT_GNU_RELRO alignment in packaged native libraries from external and Synonym artifacts.

Repro Context

adb shell getconf PAGE_SIZE
# 4096

The warning appeared on a 4 KB page-size device, so the app still runs there. The APK must still pass the stricter Android 17 compatibility checks before release.

APK inspected:

app/build/outputs/apk/dev/debug/bitkit-dev-debug-182-universal.apk

Baseline checks that already passed:

arm64-v8a PT_LOAD alignment: >= 0x4000
zipalign -v -c -P 16 4 bitkit-dev-debug-182-universal.apk: Verification successful

Failing Libraries

libandroidx.graphics.path.so       RELRO end=0x6000    source: androidx.graphics:graphics-path:1.0.1
libdatastore_shared_counter.so     RELRO end=0xd000    source: androidx.datastore:datastore-core-android:1.2.0
libpaykit.so                       RELRO end=0x859000  source: com.synonym:paykit-android:0.1.0-rc8
libsurface_util_jni.so             RELRO end=0x5000    source: androidx.camera:camera-core:1.5.2

Checked native libraries that passed in this APK:

libbitkitcore.so
libldk_node.so
libvss_rust_client_ffi.so
libjnidispatch.so
libbarhopper_v3.so
libimage_processing_util_jni.so

Requirements

External Dependencies

• Bump androidx.datastore:datastore-preferences from 1.2.0 to 1.2.1.
• Run compile, unit tests, and app launch checks after the DataStore bump.
• Verify libdatastore_shared_counter.so passes the RELRO check after the bump.
• Find a released androidx.graphics:graphics-path version where libandroidx.graphics.path.so passes the RELRO check.
• Bump/migrate Graphics Path to that version and update Bitkit code for any API changes.
• If no fixed Graphics Path version exists, file/link the upstream AndroidX issue and keep this item open until a fixed release is available or Bitkit replaces the dependency path with equivalent behavior.
• Find a released CameraX version where libsurface_util_jni.so passes the RELRO check.
• Bump/migrate CameraX to that version and update Bitkit code for any API changes.
• If no fixed CameraX version exists, file/link the upstream AndroidX issue and keep this item open until a fixed release is available or Bitkit replaces the dependency path with equivalent scanner behavior.
• Regression test DataStore-backed settings/session state across app restarts.
• Regression test QR scanner/camera initialization and scanning.
• Regression test UI surfaces that rely on AndroidX graphics/path rendering.

Synonym Artifacts

• Rebuild com.synonym:paykit-android from source with the current Android native build pipeline and NDK r28 or newer.
• Add the 16 KB compatibility check to the Paykit Android release process.
• Publish a new Paykit Android artifact after libpaykit.so passes the check.
• Bump Bitkit from com.synonym:paykit-android:0.1.0-rc8 to the fixed Paykit release.
• Verify libpaykit.so passes the RELRO check in the rebuilt Bitkit APK/AAB.
• Keep the same check in place for future Bitkit consumption of bitkit-core, ldk-node, vss-client, and other native artifacts.

Bitkit Validation

• Add scripts/check-16kb-compat.sh or equivalent.
• The script must check APK and AAB outputs for:
  • PT_LOAD alignment below 0x4000 on arm64-v8a and x86_64 libraries.
  • PT_GNU_RELRO end addresses not aligned to 0x4000 on arm64-v8a and x86_64 libraries.
  • APK zip alignment via zipalign -v -c -P 16 4.
• Add the script to release validation and CI artifact checks.
• Rebuild the affected APK/AAB artifacts.
• Confirm the rebuilt artifacts report zero failing native libraries.

Acceptance Criteria

• scripts/check-16kb-compat.sh passes for the dev debug universal APK.
• scripts/check-16kb-compat.sh passes for release APK/AAB artifacts used for distribution.
• The failing libraries listed above either pass the check or are no longer packaged.
• A fresh install on Android 17 launches without the 16 KB compatibility dialog.
• A true 16 KB page-size environment launches the app successfully.

Verification Commands

Use artifact checks as the source of truth. The Android dialog can be suppressed per install/device state.

APK=app/build/outputs/apk/dev/debug/bitkit-dev-debug-*-universal.apk
NDK_READELF="$ANDROID_HOME/ndk/28.1.13356709/toolchains/llvm/prebuilt/darwin-x86_64/bin/llvm-readelf"
ZIPALIGN="$ANDROID_HOME/build-tools/35.0.0/zipalign"

"$ZIPALIGN" -v -c -P 16 4 $APK

rm -rf /tmp/bitkit-16kb-check
mkdir -p /tmp/bitkit-16kb-check
unzip -q $APK 'lib/arm64-v8a/*.so' 'lib/x86_64/*.so' -d /tmp/bitkit-16kb-check

python3 - <<'PY'
import pathlib
import subprocess
import sys

readelf = pathlib.Path.home() / 'Library/Android/sdk/ndk/28.1.13356709/toolchains/llvm/prebuilt/darwin-x86_64/bin/llvm-readelf'
root = pathlib.Path('/tmp/bitkit-16kb-check/lib')
failed = False

for so in sorted(root.glob('*/*.so')):
    out = subprocess.check_output([str(readelf), '-l', str(so)], text=True)
    for line in out.splitlines():
        parts = line.split()
        if not parts:
            continue
        if parts[0] == 'LOAD':
            align = int(parts[-1], 16)
            if align < 0x4000:
                print(f'FAIL LOAD {so}: align=0x{align:x}')
                failed = True
        if parts[0] == 'GNU_RELRO':
            vaddr = int(parts[2], 16)
            memsz = int(parts[5], 16)
            end = vaddr + memsz
            if end % 0x4000 != 0:
                print(f'FAIL RELRO {so}: end=0x{end:x}')
                failed = True

if failed:
    sys.exit(1)
print('16 KB native compatibility checks passed')
PY

Fresh-install runtime check:

adb uninstall to.bitkit.dev || true
adb install app/build/outputs/apk/dev/debug/bitkit-dev-debug-*-universal.apk
adb shell monkey -p to.bitkit.dev -c android.intent.category.LAUNCHER 1

16 KB environment check:

adb shell getconf PAGE_SIZE
# expected: 16384