diff --git a/.github/workflows/device-tests.yml b/.github/workflows/device-tests.yml
index 5b23f2e..1a617bc 100644
--- a/.github/workflows/device-tests.yml
+++ b/.github/workflows/device-tests.yml
@@ -5,10 +5,10 @@ name: Device tests
 # assert OnAdLoaded fires. Reusable (workflow_call) so both the nightly job (published package)
 # and the MAUI auto-bump gate (source) can invoke it.
 #
-# GATING MODEL — banner is the hard gate. On a headless, software-GPU emulator (all GitHub-hosted
-# runners) only the banner format reliably fills; full-screen / native creatives need a GPU-backed
-# emulator (-gpu host) to pre-render, so they are advisory here. Set require_all_formats: true only
-# when pointing this at a GPU-capable / self-hosted runner.
+# GATING MODEL — banner is the hard gate. Measured on the hosted runner (headless, software GPU,
+# google_apis): banner and all four full-screen formats load; native/native-video do not, because
+# native demo creatives need market:// click resolution and therefore a Play Store system image.
+# Set require_all_formats: true only against a google_apis_playstore AVD on a self-hosted runner.
 
 on:
   workflow_call:
@@ -87,7 +87,13 @@ jobs:
           echo "Build props: $props"
           # -p:TargetFrameworks (not -f) so restore is single-TFM: `-f` leaves restore
           # cross-targeting, which would fail with NETSDK1147 for the iOS TFM on this runner.
-          dotnet build tests/Plugin.AdMob.DeviceTests/Plugin.AdMob.DeviceTests.csproj -c Debug -p:TargetFrameworks=net10.0-android $props
+          #
+          # EmbedAssembliesIntoApk=true is REQUIRED here. A Debug Android build otherwise uses
+          # Fast Deployment, which keeps the managed assemblies OUT of the APK and expects the
+          # IDE / `dotnet build -t:Run` to push them separately. Installing such an APK with
+          # plain `adb install` yields an app that aborts at startup with
+          # "No assemblies found in .../.__override__/x86_64" before a single line is logged.
+          dotnet build tests/Plugin.AdMob.DeviceTests/Plugin.AdMob.DeviceTests.csproj -c Debug -p:TargetFrameworks=net10.0-android -p:EmbedAssembliesIntoApk=true $props
           apk=$(find "$PWD/tests/Plugin.AdMob.DeviceTests/bin" -name '*-Signed.apk' | head -1)
           if [ -z "$apk" ]; then apk=$(find "$PWD/tests/Plugin.AdMob.DeviceTests/bin" -name '*.apk' | head -1); fi
           if [ -z "$apk" ]; then echo "::error::No APK produced"; exit 1; fi
@@ -101,6 +107,9 @@ jobs:
           api-level: 34
           arch: x86_64
           target: google_apis
+          # Embedding the assemblies takes the APK from ~13 MB to ~90 MB; give the AVD headroom
+          # so the install can't fail with INSTALL_FAILED_INSUFFICIENT_STORAGE.
+          disk-size: 8G
           force-avd-creation: false
           disable-animations: true
           emulator-options: -no-window -gpu swiftshader_indirect -noaudio -no-boot-anim -camera-back none -no-snapshot
@@ -115,6 +124,16 @@ jobs:
         with:
           ref: ${{ inputs.ref || github.ref }}
 
+      # .NET for iOS hard-pins a required Xcode and the image's *selected* Xcode can lag it —
+      # the 2026-07-25 nightly failed with "This version of .NET for iOS (26.5.10301) requires
+      # Xcode 26.6. The current version of Xcode is 26.5." Images usually carry several Xcodes,
+      # so select the newest; the listing makes the mismatch obvious if one is still missing.
+      - name: Select the newest available Xcode
+        run: |
+          ls -d /Applications/Xcode*.app || true
+          sudo xcode-select -s "$(ls -d /Applications/Xcode*.app | sort -V | tail -1)"
+          xcodebuild -version
+
       - uses: actions/setup-dotnet@v4
         with:
           dotnet-version: 10.0.x
diff --git a/tests/Plugin.AdMob.DeviceTests/AdLoadHarness.cs b/tests/Plugin.AdMob.DeviceTests/AdLoadHarness.cs
index 7cd668f..1655f4d 100644
--- a/tests/Plugin.AdMob.DeviceTests/AdLoadHarness.cs
+++ b/tests/Plugin.AdMob.DeviceTests/AdLoadHarness.cs
@@ -11,12 +11,14 @@ namespace Plugin.AdMob.DeviceTests;
 /// on-screen rendering is what makes this a stable signal for catching upstream binding /
 /// MAUI drift in the published package.
 ///
-/// Environment note baked in from the maintainer's own testing: on a headless, software-GPU
-/// emulator (GitHub-hosted runners have no GPU) only the BANNER format reliably fills. The
-/// full-screen and native formats need a GPU-backed emulator (-gpu host) to pre-render their
-/// creative and otherwise come back as no-fill. Hence two summary lines are emitted:
+/// Environment note, measured on the GitHub-hosted runner (headless, software GPU, google_apis
+/// image): banner AND the full-screen formats (interstitial, rewarded, rewarded-interstitial,
+/// app-open) all load fine. Only NATIVE and NATIVE-VIDEO fail there with "Internal error" —
+/// native demo ads are app-install creatives whose click actions need market:// resolution, so
+/// they want a Play Store system image (google_apis_playstore), not merely a GPU. Hence two
+/// summary lines are emitted:
 ///   SUMMARY_BANNER — the format CI can hard-gate on any runner.
-///   SUMMARY_ALL    — every format; only meaningful (hard-gate-able) on a -gpu host runner.
+///   SUMMARY_ALL    — every format; only hard-gate-able on a Play Store image.
 /// </summary>
 internal static class AdLoadHarness
 {
diff --git a/tests/README.md b/tests/README.md
index e3818b7..0710acf 100644
--- a/tests/README.md
+++ b/tests/README.md
@@ -44,11 +44,19 @@ dotnet build tests/Plugin.AdMob.DeviceTests/Plugin.AdMob.DeviceTests.csproj -f n
 
 ## The banner-vs-full-screen gating model (important)
 
-On a **headless, software-GPU emulator** — which is every GitHub-hosted runner, since they have
-no GPU — only the **banner** format reliably fills. Full-screen (interstitial / rewarded /
-rewarded-interstitial / app-open) and native creatives need a **GPU-backed emulator (`-gpu host`)**
-to pre-render, and otherwise come back as no-fill. This is a documented, hardware-observed quirk,
-not a plugin bug.
+Not every format fills in every environment, and that is an environment property rather than a
+plugin bug. Measured on the GitHub-hosted runner (headless, software GPU, `google_apis` image):
+
+| Format | Headless CI (`google_apis`) | Local `-gpu host` + Play Store image |
+|---|---|---|
+| banner | ✅ | ✅ |
+| interstitial / rewarded / rewarded-interstitial / app-open | ✅ | ✅ |
+| native, native-video | ❌ `Internal error` | ✅ |
+
+So the full-screen formats *do* load headless. The one real gap is **native**, which serves
+app-install creatives whose click actions need `market://` resolution — that requires a
+**Play Store** system image (`google_apis_playstore`), not merely a GPU. Loads are also
+occasionally flaky (`Internal error` on a first attempt), which is why each format gets a retry.
 
 So the harness emits two summary lines and CI gates accordingly:
 
@@ -56,19 +64,32 @@ So the harness emits two summary lines and CI gates accordingly:
 - `SUMMARY_ALL` → every format; only hard-gated when `require_all_formats: true`.
 
 To get **full-format** coverage, run `device-tests.yml` (or the harness directly) against a
-**`-gpu host` emulator on a self-hosted runner** and pass `require_all_formats: true`. The
-maintainer's local `plugin_admob_ps` (Play Store) AVD is exactly such an environment.
+**Play Store (`google_apis_playstore`) AVD on a self-hosted runner** and pass
+`require_all_formats: true`. The maintainer's local `plugin_admob_ps` AVD is exactly that.
 
-Run the harness locally against a booted `-gpu host` emulator:
+Run the harness locally against a booted emulator:
 
 ```bash
-dotnet build tests/Plugin.AdMob.DeviceTests/Plugin.AdMob.DeviceTests.csproj -c Debug -f net10.0-android \
+dotnet build tests/Plugin.AdMob.DeviceTests/Plugin.AdMob.DeviceTests.csproj -c Debug \
+  -p:TargetFrameworks=net10.0-android -p:EmbedAssembliesIntoApk=true \
   "-p:AndroidSdkDirectory=%LOCALAPPDATA%\Android\Sdk" "-p:JavaSdkDirectory=%LOCALAPPDATA%\Android\Jdk"
 adb install -r tests/Plugin.AdMob.DeviceTests/bin/Debug/net10.0-android/com.plugin.admob.devicetests-Signed.apk
 adb logcat -c && adb shell monkey -p com.plugin.admob.devicetests -c android.intent.category.LAUNCHER 1
 adb logcat -s AdMobHarness:I   # watch RESULT / SUMMARY_* lines
 ```
 
+`EmbedAssembliesIntoApk=true` is **required** whenever you install with `adb install`. Without
+it a Debug build uses Fast Deployment, leaves the managed assemblies out of the APK, and the app
+aborts at startup with `No assemblies found in .../.__override__/...` before logging anything.
+
+### Known-broken: the iOS leg
+
+The iOS simulator job currently cannot build on GitHub's macOS image. .NET for iOS 26.5.10301
+requires Xcode 26.6; the image's *selected* Xcode is 26.5, and while 26.6 is installed it ships
+without the macOS platform SDK, so `actool` fails (`SDK "…/MacOSX.sdk" cannot be located`). The
+job selects the newest Xcode and stays `continue-on-error`, so it never blocks — the run is still
+green. iOS *compilation* is covered by `build.yml`'s `net10.0-ios` leg, which passes.
+
 ## One manual step: make the gates required
 
 Workflows run automatically, but marking them **required status checks** is a repository
diff --git a/tests/ci/run-android-harness.sh b/tests/ci/run-android-harness.sh
index ec94c53..ea9dc5b 100644
--- a/tests/ci/run-android-harness.sh
+++ b/tests/ci/run-android-harness.sh
@@ -4,16 +4,27 @@ set -euo pipefail
 # Installs the pre-built device-test APK on the booted emulator, launches it, and scrapes the
 # harness's result lines from logcat.
 #
-# Banner is the hard gate: it is the one format that reliably fills on a headless, software-GPU
-# emulator (GitHub-hosted runners have no GPU). The full set (SUMMARY_ALL) is only enforced when
-# REQUIRE_ALL=true — i.e. when running against a GPU-backed / -gpu host emulator (e.g. a
-# self-hosted runner) where full-screen and native creatives can actually pre-render and fill.
+# Banner is the hard gate. On the hosted runner's google_apis image the full-screen formats load
+# too, but native/native-video do not (they need a Play Store image for market:// click
+# resolution), so the full set (SUMMARY_ALL) is only enforced when REQUIRE_ALL=true — i.e. against
+# a google_apis_playstore AVD on a self-hosted runner.
 
 PKG="com.plugin.admob.devicetests"
 TAG="AdMobHarness"
 REQUIRE_ALL="${REQUIRE_ALL:-false}"
 APK="${APK:?APK env var not set}"
 
+# Dumped whenever the harness produces no usable result. Without this a startup crash is
+# invisible: the tag-filtered log below is simply empty and says nothing about why.
+dump_diagnostics() {
+  echo "===== app process ====="
+  adb shell pidof "$PKG" || echo "(app is not running)"
+  echo "===== fatal / crash ====="
+  adb logcat -d -s AndroidRuntime:E monodroid:F monodroid-assembly:F DEBUG:F 2>/dev/null | tail -40 || true
+  echo "===== last 120 log lines (unfiltered) ====="
+  adb logcat -d 2>/dev/null | tail -120 || true
+}
+
 echo "Installing $APK"
 adb install -r "$APK"
 
@@ -49,11 +60,13 @@ echo "all:     ${allline:-<none>}"
 
 if [ -z "$banner" ]; then
   echo "::error::Harness did not report a banner result (app crashed or never finished loading)."
+  dump_diagnostics
   exit 1
 fi
 
 if ! echo "$banner" | grep -q "status=PASS"; then
   echo "::error::Banner ad failed to load against Google's test ad unit."
+  dump_diagnostics
   exit 1
 fi