detemine root cause of download issue.

app/lib/whisper.ts

@@ -136,12 +136,32 @@ export function whisperFileExists(whisper_model : whisper_model_tag_t) {
   return target.exists
 }
 
-export async function downloadWhisperModel(
+export type DownloadCallback = (arg0 : FileSystem.DownloadProgressData) => any;
+
+async function updateModelSize(model_label : string, size : number) {
+  const db = await getDb();
+  const query = "INSERT OR REPLACE INTO whisper_models (model, bytes_total) VALUES (?, ?)"
+  const stmt = db.prepareSync(query);
+  stmt.executeSync(model_label, size);
+}
+
+async function getExpectedModelSize(model_label : string) : Promise<number | undefined> {
+  const db = await getDb();
+  const query = "SELECT bytes_total FROM whisper_models WHERE model = ?"
+  const stmt = db.prepareSync(query);
+  const curs = stmt.executeSync(model_label);
+  const row = curs.getFirstSync()
+  return row ? row.bytes_total : undefined;
+}
+
+export async function initiateWhisperDownload(
   whisper_model: whisper_model_tag_t,
   options: {
-    force_redownload: boolean;
+    force_redownload?: boolean;
+    onDownload?: DownloadCallback | undefined;
   } = {
     force_redownload: false,
+    onDownload: undefined,
   }
 ) {
 
@@ -161,34 +181,33 @@ export async function downloadWhisperModel(
     if (options.force_redownload) {
       whisperTarget.delete()
     } else {
-      console.warn("Whisper model for %s already exists", whisper_model);
-      return;
+      const expected = await getExpectedModelSize(whisper_model);
+      if (whisperTarget.size === expected) {
+        console.warn("Whisper model for %s already exists", whisper_model);
+        return undefined;
+      }
     }
   }
 
   // Initiate a new resumable download.
   const spec = WHISPER_MODELS[whisper_model];
+
+  console.log("Downloading %s", spec.source);
+
   const resumable = FileSystem.createDownloadResumable(
     spec.source,
     whisperTarget.uri,
-    undefined,
+    {},
     // On each data write, update the whisper model download status.
     // Note that since createDownloadResumable callback only works in the foreground,
     // a background process will also be updating the file size.
     async (data) => {
-      const db = await getDb();
-      const args = [
-        whisper_model,
-        data.totalBytesWritten,
-        data.totalBytesExpectedToWrite,
-      ];
-      console.log("%s, %s of %s", whisper_model, data.totalBytesWritten, data.totalBytesExpectedToWrite);
-      await db.runAsync(
-        `INSERT OR REPLACE INTO whisper_models (model, bytes_done, bytes_remaining) VALUES (?, ?, ?)`,
-        args
-      );
-    }
+      console.log("%s: %d bytes of %d", whisperTarget.uri, data.totalBytesWritten, data.totalBytesExpectedToWrite);
+      await updateModelSize(whisper_model, data.totalBytesExpectedToWrite)
+      if (options.onDownload) await options.onDownload(data);
+    },
+    whisperTarget.exists ? whisperTarget.base64() : undefined,
   );
 
-  await resumable.downloadAsync();
+  return resumable;
 }