Add AppCacheExclusionPlugin so modules can exclude files from being removed (#6551)

Task/Issue URL:
https://app.asana.com/1/137249556945/project/488551667048375/task/1210997578538480?focus=true

### Description
Allow modules to exclude cache files from being removed.

### Steps to test this PR

_No regression_
- [ ] Add the following to your logcat filter `message~:"Subscription
features for base plan|Subscriptions response came from"`
- [ ] Checkout this branch
- [ ] Apply patch attached in
https://app.asana.com/1/137249556945/project/488551667048375/task/1210997578538480?focus=true
- [ ] Fresh install
- [ ] Check in the logs you hit the Network and you receive the features
- [ ] Fire button
- [ ] Check in the logs you hit the Cache
- [ ] Kill the app manually, open it again
- [ ] Check in the logs you hit the Cache

_fdroid build_
https://github.com/duckduckgo/Android/actions/runs/16828352038 should
pass

### UI changes
| Before  | After |
| ------ | ----- |
!(Upload before screenshot)|(Upload after screenshot)|

Author: cmonfortep

app/src/main/java/com/duckduckgo/app/di/PrivacyModule.kt

@@ -28,6 +28,7 @@ import com.duckduckgo.app.fire.DataClearerForegroundAppRestartPixel
 import com.duckduckgo.app.fire.DataClearerTimeKeeper
 import com.duckduckgo.app.fire.UnsentForgetAllPixelStore
 import com.duckduckgo.app.fire.fireproofwebsite.data.FireproofWebsiteRepository
+import com.duckduckgo.app.fire.model.AppCacheExclusionPlugin
 import com.duckduckgo.app.global.file.FileDeleter
 import com.duckduckgo.app.global.view.ClearDataAction
 import com.duckduckgo.app.global.view.ClearPersonalDataAction
@@ -43,6 +44,7 @@ import com.duckduckgo.app.trackerdetection.api.WebTrackersBlockedRepository
 import com.duckduckgo.app.trackerdetection.db.TdsDomainEntityDao
 import com.duckduckgo.app.trackerdetection.db.TdsEntityDao
 import com.duckduckgo.common.utils.DispatcherProvider
+import com.duckduckgo.common.utils.plugins.PluginPoint
 import com.duckduckgo.cookies.api.DuckDuckGoCookieManager
 import com.duckduckgo.di.scopes.AppScope
 import com.duckduckgo.history.api.NavigationHistory
@@ -125,8 +127,9 @@ object PrivacyModule {
     fun appCacheCleaner(
         context: Context,
         fileDeleter: FileDeleter,
+        exclusionPlugins: PluginPoint<AppCacheExclusionPlugin>,
     ): AppCacheClearer {
-        return AndroidAppCacheClearer(context, fileDeleter)
+        return AndroidAppCacheClearer(context, fileDeleter, exclusionPlugins)
     }
 
     @Provides

app/src/main/java/com/duckduckgo/app/fire/AppCacheClearer.kt

@@ -18,9 +18,10 @@ package com.duckduckgo.app.fire
 
 import android.content.Context
 import com.duckduckgo.app.browser.favicon.FileBasedFaviconPersister.Companion.FAVICON_PERSISTED_DIR
+import com.duckduckgo.app.fire.model.AppCacheExclusionPlugin
 import com.duckduckgo.app.global.api.NetworkApiCache
 import com.duckduckgo.app.global.file.FileDeleter
-import com.duckduckgo.subscriptions.impl.services.SubscriptionNetworkModule.Companion.SUBSCRIPTION_CACHE_FILE
+import com.duckduckgo.common.utils.plugins.PluginPoint
 
 interface AppCacheClearer {
 
@@ -30,10 +31,13 @@ interface AppCacheClearer {
 class AndroidAppCacheClearer(
     private val context: Context,
     private val fileDeleter: FileDeleter,
+    private val exclusionPlugins: PluginPoint<AppCacheExclusionPlugin>,
 ) : AppCacheClearer {
 
     override suspend fun clearCache() {
-        fileDeleter.deleteContents(context.cacheDir, FILENAMES_EXCLUDED_FROM_DELETION)
+        val pluginExclusions = exclusionPlugins.getPlugins().flatMap { it.filenamesExcludedFromDeletion() }
+        val exclusions = (FILENAMES_EXCLUDED_FROM_DELETION + pluginExclusions).distinct()
+        fileDeleter.deleteContents(context.cacheDir, exclusions)
     }
 
     companion object {
@@ -53,10 +57,7 @@ class AndroidAppCacheClearer(
          */
         private const val NETWORK_CACHE_DIR = NetworkApiCache.FILE_NAME
 
-        // TODO: We need to allow other modules to contribute this list
-        // https://app.asana.com/1/137249556945/project/1149059203486286/task/1210997578538480?focus=true
         private val FILENAMES_EXCLUDED_FROM_DELETION = listOf(
-            SUBSCRIPTION_CACHE_FILE,
             WEBVIEW_CACHE_DIR,
             WEBVIEW_CACHE_DIR_LEGACY,
             NETWORK_CACHE_DIR,

app/src/main/java/com/duckduckgo/app/fire/AppCacheExclusionPluginPoint.kt

@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2025 DuckDuckGo
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.duckduckgo.app.fire
+
+import com.duckduckgo.anvil.annotations.ContributesPluginPoint
+import com.duckduckgo.app.fire.model.AppCacheExclusionPlugin
+import com.duckduckgo.di.scopes.AppScope
+
+@ContributesPluginPoint(
+    scope = AppScope::class,
+    boundType = AppCacheExclusionPlugin::class,
+)
+@Suppress("unused")
+interface AppCacheExclusionPluginPoint

browser-api/src/main/java/com/duckduckgo/app/fire/model/AppCacheExclusionPlugin.kt

@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2025 DuckDuckGo
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.duckduckgo.app.fire.model
+
+/**
+ * Modules can implement this plugin to contribute top-level filenames inside [Context.getCacheDir]
+ * that MUST be preserved when the app clears its cache directory.
+ */
+interface AppCacheExclusionPlugin {
+    /**
+     * @return list of filenames (top-level entries in cacheDir) that should NOT be deleted
+     */
+    fun filenamesExcludedFromDeletion(): List<String>
+}

subscriptions/subscriptions-impl/src/main/java/com/duckduckgo/subscriptions/impl/services/SubscriptionsCacheExclusionPlugin.kt

@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2025 DuckDuckGo
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.duckduckgo.subscriptions.impl.services
+
+import com.duckduckgo.app.fire.model.AppCacheExclusionPlugin
+import com.duckduckgo.di.scopes.AppScope
+import com.squareup.anvil.annotations.ContributesMultibinding
+import javax.inject.Inject
+
+@ContributesMultibinding(AppScope::class)
+class SubscriptionsCacheExclusionPlugin @Inject constructor() : AppCacheExclusionPlugin {
+    override fun filenamesExcludedFromDeletion(): List<String> {
+        return listOf(SubscriptionNetworkModule.SUBSCRIPTION_CACHE_FILE)
+    }
+}