Relay share intents through a headless activity

android/app/src/main/AndroidManifest.xml

@@ -27,17 +27,6 @@
         <action android:name="android.intent.action.MAIN"/>
         <category android:name="android.intent.category.LAUNCHER"/>
       </intent-filter>
-      <!-- Share target. Without this filter the app never appears in the
-           system share sheet at all; image/* only, the editor takes photos.
-           Goes on the launcher activity: it is singleTask, so a share
-           re-delivered there replaces its intent (onNewIntent -> setIntent)
-           and the running app picks the photo up without a cold start. -->
-      <intent-filter>
-        <action android:name="android.intent.action.SEND"/>
-        <action android:name="android.intent.action.SEND_MULTIPLE"/>
-        <category android:name="android.intent.category.DEFAULT"/>
-        <data android:mimeType="image/*"/>
-      </intent-filter>
       <intent-filter>
         <action android:name="android.intent.action.VIEW"/>
         <category android:name="android.intent.category.DEFAULT"/>
@@ -45,5 +34,19 @@
         <data android:scheme="exp+recipescamera"/>
       </intent-filter>
     </activity>
+    <!-- Share target. Without this filter the app never appears in the
+         system share sheet at all; image/* only, the editor takes photos.
+         A separate no-display relay, not MainActivity: a host app that starts
+         the target without FLAG_ACTIVITY_NEW_TASK would otherwise drop the
+         editor into its own task and the share would look like part of it.
+         ShareActivity relaunches MainActivity in our own task instead. -->
+    <activity android:name=".ShareActivity" android:theme="@android:style/Theme.NoDisplay" android:launchMode="standard" android:excludeFromRecents="true" android:exported="true">
+      <intent-filter>
+        <action android:name="android.intent.action.SEND"/>
+        <action android:name="android.intent.action.SEND_MULTIPLE"/>
+        <category android:name="android.intent.category.DEFAULT"/>
+        <data android:mimeType="image/*"/>
+      </intent-filter>
+    </activity>
   </application>
 </manifest>