From 86397e0980839c375ea5fa9103fad920c40f9c7d Mon Sep 17 00:00:00 2001
From: Davide Scaini <davide.scaini@alumni.cern>
Date: Thu, 4 Jun 2026 01:06:39 +0200
Subject: [PATCH] =?UTF-8?q?fix:=20offline=20download=20=E2=80=94=20wait=20?=
 =?UTF-8?q?for=20completion,=20suppress=20transient=20errors?=
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createPack() resolves when the pack is registered, not when tiles are
done downloading. Wrapping in a Promise that resolves only on
status.state === 'complete' keeps the progress modal visible and the
'Download complete' alert fires only when the pack is actually ready.

Transient tile errors ('stream was reset: CANCEL') are silently ignored
in the error listener — MapLibre retries them internally and they do not
indicate a failed download. The onError callback is removed from the
public API since it was causing spurious alerts mid-download.
---
 src/screens/RecordingScreen.tsx |  1 -
 src/services/offline.ts         | 48 ++++++++++++++++++++-------------
 2 files changed, 30 insertions(+), 19 deletions(-)

diff --git a/src/screens/RecordingScreen.tsx b/src/screens/RecordingScreen.tsx
index 03861e1..c329a32 100644
--- a/src/screens/RecordingScreen.tsx
+++ b/src/screens/RecordingScreen.tsx
@@ -110,7 +110,6 @@ export function RecordingScreen() {
         dlName.trim(),
         expanded,
         (pct, _tiles, sizeBytes) => { setDlProgress(pct); setDlSize(sizeBytes); },
-        (msg) => Alert.alert('Download error', msg),
       );
       setDlVisible(false);
       setDlProgress(null);
diff --git a/src/services/offline.ts b/src/services/offline.ts
index 0bb951a..875eb85 100644
--- a/src/services/offline.ts
+++ b/src/services/offline.ts
@@ -22,31 +22,43 @@ export interface OfflineRegion {
 
 // ── Download ──────────────────────────────────────────────────────────────────
 
-export async function downloadRegion(
+/**
+ * Download a region and return a Promise that resolves only when the pack
+ * reaches state 'complete'. Transient tile-fetch errors (e.g. "stream was
+ * reset: CANCEL") are silently ignored — MapLibre retries them internally
+ * and they do not indicate a failed download.
+ */
+export function downloadRegion(
   name: string,
   bounds: LngLatBounds,
   onProgress: (pct: number, tilesDown: number, sizeBytes: number) => void,
-  onError: (msg: string) => void,
 ): Promise<string> {
   OfflineManager.setProgressEventThrottle(500);
 
-  const pack = await OfflineManager.createPack(
-    {
-      mapStyle: OFFLINE_STYLE_URL,
-      bounds,
-      minZoom: MIN_ZOOM,
-      maxZoom: MAX_ZOOM,
-      metadata: { name, createdAt: new Date().toISOString() },
-    },
-    (_pack, status: OfflinePackStatus) => {
-      onProgress(status.percentage, status.completedTileCount, status.completedTileSize);
-    },
-    (_pack, error) => {
-      onError(error.message);
-    },
-  );
+  return new Promise((resolve, reject) => {
+    let packId: string;
 
-  return pack.id;
+    OfflineManager.createPack(
+      {
+        mapStyle: OFFLINE_STYLE_URL,
+        bounds,
+        minZoom: MIN_ZOOM,
+        maxZoom: MAX_ZOOM,
+        metadata: { name, createdAt: new Date().toISOString() },
+      },
+      (pack, status: OfflinePackStatus) => {
+        packId = pack.id;
+        onProgress(status.percentage, status.completedTileCount, status.completedTileSize);
+        if (status.state === 'complete') {
+          resolve(packId);
+        }
+      },
+      (_pack, _error) => {
+        // Transient tile-level errors — MapLibre retries these automatically.
+        // Do not reject: the overall download is still in progress.
+      },
+    ).catch(reject); // only rejects on createPack failure (e.g. bad style URL)
+  });
 }
 
 // ── List ──────────────────────────────────────────────────────────────────────