diff --git a/android/app/src/main/kotlin/com/zarz/spotiflac/NativeDownloadFinalizer.kt b/android/app/src/main/kotlin/com/zarz/spotiflac/NativeDownloadFinalizer.kt
index e1be1648..f3ab43d4 100644
--- a/android/app/src/main/kotlin/com/zarz/spotiflac/NativeDownloadFinalizer.kt
+++ b/android/app/src/main/kotlin/com/zarz/spotiflac/NativeDownloadFinalizer.kt
@@ -424,91 +424,6 @@ object NativeDownloadFinalizer {
         }
     }
 
-    private fun runPostProcessing(
-        context: Context,
-        input: FinalizeInput,
-        state: FinalizeState,
-        shouldCancel: () -> Boolean,
-    ) {
-        if (!input.request.optBoolean("post_processing_enabled", false)) return
-        val metadata = JSONObject()
-            .put("title", trackString(input, "name", input.request.optString("track_name", "")))
-            .put("artist", trackString(input, "artistName", input.request.optString("artist_name", "")))
-            .put("album", trackString(input, "albumName", input.request.optString("album_name", "")))
-            .put("album_artist", resolvedAlbumArtist(input))
-            .put("track_number", trackInt(input, "trackNumber", input.request.optInt("track_number", 0)))
-            .put("disc_number", trackInt(input, "discNumber", input.request.optInt("disc_number", 0)))
-            .put("isrc", trackString(input, "isrc", input.request.optString("isrc", "")))
-            .put("release_date", trackString(input, "releaseDate", input.request.optString("release_date", "")))
-            .put("duration_ms", trackInt(input, "duration", 0) * 1000)
-            .put("cover_url", metadataCoverUrl(input))
-
-        if (state.filePath.startsWith("content://")) {
-            val uri = state.filePath
-            val tempInput = SafDownloadHandler.copyContentUriToTemp(context, uri)
-                ?: throw IllegalStateException("failed to copy SAF file for post-processing")
-            try {
-                val inputObj = JSONObject()
-                    .put("item_id", input.itemId)
-                    .put("path", tempInput)
-                    .put("uri", uri)
-                    .put("name", state.fileName)
-                    .put("mime_type", mimeTypeForExt(state.fileName.substringAfterLast('.', "")))
-                    .put("size", File(tempInput).length())
-                    .put("is_saf", true)
-                checkCancelled(shouldCancel)
-                val response = JSONObject(createCoreBackend(context).runPostProcessing(inputObj.toString(), metadata.toString()))
-                checkCancelled(shouldCancel)
-                if (!response.optBoolean("success", false)) return
-                val newPath = response.optString("new_file_path", "")
-                val outputPath = newPath.ifBlank { tempInput }
-                val outputFile = File(outputPath)
-                if (!outputFile.exists()) return
-                val outputName = if (newPath.isBlank()) state.fileName else outputFile.name
-                val newUri = SafDownloadHandler.writeFileToSaf(
-                    context = context,
-                    treeUriStr = input.request.optString("saf_tree_uri", ""),
-                    relativeDir = input.request.optString("saf_relative_dir", ""),
-                    fileName = outputName,
-                    mimeType = mimeTypeForExt(outputFile.extension),
-                    srcPath = outputFile.absolutePath,
-                ) ?: return
-                if (newUri != uri) SafDownloadHandler.deleteContentUri(context, uri)
-                state.filePath = newUri
-                state.fileName = outputName
-                if (outputPath != tempInput) outputFile.delete()
-            } finally {
-                File(tempInput).delete()
-            }
-            return
-        }
-
-        val inputObj = JSONObject()
-            .put("item_id", input.itemId)
-            .put("path", state.filePath)
-            .put("name", state.fileName)
-            .put("is_saf", false)
-        checkCancelled(shouldCancel)
-        val response = JSONObject(createCoreBackend(context).runPostProcessing(inputObj.toString(), metadata.toString()))
-        checkCancelled(shouldCancel)
-        if (response.optBoolean("success", false)) {
-            val newPath = response.optString("new_file_path", "")
-            if (newPath.isNotBlank() && newPath != state.filePath) {
-                if (isDeferredSafPublish(input)) {
-                    val output = File(newPath)
-                    check(output.isFile && output.length() > 0L) {
-                        "post-processing output missing or empty"
-                    }
-                    // This input is an owned staging file; publication later
-                    // removes the replacement, so retire the old stage now.
-                    File(state.filePath).delete()
-                }
-                state.filePath = newPath
-                state.fileName = File(newPath).name
-            }
-        }
-    }
-
     internal fun materializeForFFmpeg(context: Context, input: FinalizeInput, state: FinalizeState): String {
         if (!state.filePath.startsWith("content://")) return state.filePath
         return SafDownloadHandler.copyContentUriToTemp(context, state.filePath)
diff --git a/android/app/src/main/kotlin/com/zarz/spotiflac/NativeFinalizerPostProcess.kt b/android/app/src/main/kotlin/com/zarz/spotiflac/NativeFinalizerPostProcess.kt
new file mode 100644
index 00000000..96d6fc89
--- /dev/null
+++ b/android/app/src/main/kotlin/com/zarz/spotiflac/NativeFinalizerPostProcess.kt
@@ -0,0 +1,94 @@
+package com.zarz.spotiflac
+
+import android.content.Context
+import com.zarz.spotiflac.SafDownloadHandler.mimeTypeForExt
+import org.json.JSONObject
+import java.io.File
+
+
+// Extension post-processing hook stage for NativeDownloadFinalizer.
+
+internal fun NativeDownloadFinalizer.runPostProcessing(
+    context: Context,
+    input: NativeDownloadFinalizer.FinalizeInput,
+    state: NativeDownloadFinalizer.FinalizeState,
+    shouldCancel: () -> Boolean,
+) {
+    if (!input.request.optBoolean("post_processing_enabled", false)) return
+    val metadata = JSONObject()
+        .put("title", trackString(input, "name", input.request.optString("track_name", "")))
+        .put("artist", trackString(input, "artistName", input.request.optString("artist_name", "")))
+        .put("album", trackString(input, "albumName", input.request.optString("album_name", "")))
+        .put("album_artist", resolvedAlbumArtist(input))
+        .put("track_number", trackInt(input, "trackNumber", input.request.optInt("track_number", 0)))
+        .put("disc_number", trackInt(input, "discNumber", input.request.optInt("disc_number", 0)))
+        .put("isrc", trackString(input, "isrc", input.request.optString("isrc", "")))
+        .put("release_date", trackString(input, "releaseDate", input.request.optString("release_date", "")))
+        .put("duration_ms", trackInt(input, "duration", 0) * 1000)
+        .put("cover_url", metadataCoverUrl(input))
+
+    if (state.filePath.startsWith("content://")) {
+        val uri = state.filePath
+        val tempInput = SafDownloadHandler.copyContentUriToTemp(context, uri)
+            ?: throw IllegalStateException("failed to copy SAF file for post-processing")
+        try {
+            val inputObj = JSONObject()
+                .put("item_id", input.itemId)
+                .put("path", tempInput)
+                .put("uri", uri)
+                .put("name", state.fileName)
+                .put("mime_type", mimeTypeForExt(state.fileName.substringAfterLast('.', "")))
+                .put("size", File(tempInput).length())
+                .put("is_saf", true)
+            checkCancelled(shouldCancel)
+            val response = JSONObject(createCoreBackend(context).runPostProcessing(inputObj.toString(), metadata.toString()))
+            checkCancelled(shouldCancel)
+            if (!response.optBoolean("success", false)) return
+            val newPath = response.optString("new_file_path", "")
+            val outputPath = newPath.ifBlank { tempInput }
+            val outputFile = File(outputPath)
+            if (!outputFile.exists()) return
+            val outputName = if (newPath.isBlank()) state.fileName else outputFile.name
+            val newUri = SafDownloadHandler.writeFileToSaf(
+                context = context,
+                treeUriStr = input.request.optString("saf_tree_uri", ""),
+                relativeDir = input.request.optString("saf_relative_dir", ""),
+                fileName = outputName,
+                mimeType = mimeTypeForExt(outputFile.extension),
+                srcPath = outputFile.absolutePath,
+            ) ?: return
+            if (newUri != uri) SafDownloadHandler.deleteContentUri(context, uri)
+            state.filePath = newUri
+            state.fileName = outputName
+            if (outputPath != tempInput) outputFile.delete()
+        } finally {
+            File(tempInput).delete()
+        }
+        return
+    }
+
+    val inputObj = JSONObject()
+        .put("item_id", input.itemId)
+        .put("path", state.filePath)
+        .put("name", state.fileName)
+        .put("is_saf", false)
+    checkCancelled(shouldCancel)
+    val response = JSONObject(createCoreBackend(context).runPostProcessing(inputObj.toString(), metadata.toString()))
+    checkCancelled(shouldCancel)
+    if (response.optBoolean("success", false)) {
+        val newPath = response.optString("new_file_path", "")
+        if (newPath.isNotBlank() && newPath != state.filePath) {
+            if (isDeferredSafPublish(input)) {
+                val output = File(newPath)
+                check(output.isFile && output.length() > 0L) {
+                    "post-processing output missing or empty"
+                }
+                // This input is an owned staging file; publication later
+                // removes the replacement, so retire the old stage now.
+                File(state.filePath).delete()
+            }
+            state.filePath = newPath
+            state.fileName = File(newPath).name
+        }
+    }
+}