Abandon staged install session when a download is cancelled

Cancelling a download cancelled the worker and marked the row CANCELLED but
never abandoned a PackageInstaller session that had already been staged for
install, leaking it. Add IInstaller.cancelInstall (no-op default, implemented by
SessionInstaller) and call it from DownloadHelper.cancelDownload.

Cross-process session persistence/reconciliation (committing a session staged
before a restart) is left as a follow-up; the startup session cleanup remains,
and is now cheap to recover from since CacheWorker keeps the downloaded files.

app/src/main/java/com/aurora/store/data/helper/DownloadHelper.kt

@@ -162,6 +162,8 @@ class DownloadHelper @Inject constructor(
     suspend fun cancelDownload(packageName: String) {
         Log.i(TAG, "Cancelling download for $packageName")
         WorkManager.getInstance(context).cancelAllWorkByTag("$PACKAGE_NAME:$packageName")
+        // Abandon any session already staged for install so we don't leak it.
+        runCatching { appInstaller.getPreferredInstaller().cancelInstall(packageName) }
         downloadDao.updateStatus(packageName, DownloadStatus.CANCELLED)
     }
 

app/src/main/java/com/aurora/store/data/installer/SessionInstaller.kt

@@ -182,6 +182,16 @@ class SessionInstaller @Inject constructor(
         }
     }
 
+    override fun cancelInstall(packageName: String) {
+        val sessionSet = enqueuedSessions
+            .find { set -> set.any { it.packageName == packageName } } ?: return
+
+        Log.i(TAG, "Abandoning staged session(s) for $packageName")
+        sessionSet.forEach { runCatching { packageInstaller.abandonSession(it.sessionId) } }
+        enqueuedSessions.remove(sessionSet)
+        removeFromInstallQueue(packageName)
+    }
+
     private fun stageInstall(
         packageName: String,
         versionCode: Long,

app/src/main/java/com/aurora/store/data/installer/base/IInstaller.kt

@@ -26,4 +26,11 @@ interface IInstaller {
     fun clearQueue()
     fun isAlreadyQueued(packageName: String): Boolean
     fun removeFromInstallQueue(packageName: String)
+
+    /**
+     * Abandons any staged-but-uncommitted install session for [packageName] so cancelling
+     * a download doesn't leak a [android.content.pm.PackageInstaller] session. Default no-op
+     * for installers that don't stage sessions.
+     */
+    fun cancelInstall(packageName: String) {}
 }