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Prevent blob eviction: store as ArrayBuffer + request persistence

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iOS Safari evicts Blob file-backed data from IndexedDB under memory
pressure, causing upload POSTs to throw 'Load failed' without ever
reaching the server. Two-pronged fix:

1. Store photos as ArrayBuffer (inline bytes) instead of Blob (file
   reference) in IndexedDB — ArrayBuffers are not subject to eviction
2. Request navigator.storage.persist() to signal the browser not to
   evict our storage under pressure

Also adds Storage.getBlob() helper for converting stored ArrayBuffer
back to Blob at upload/display time, with backward compat for any
existing Blob-stored photos.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
This commit is contained in:
kamaji
2026-02-07 16:01:07 -06:00
parent 1da3eea7b8
commit 5105b42c46
5 changed files with 48 additions and 57 deletions
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34
app/static/js/sync.js
View File

@@ -137,31 +137,18 @@ const Sync = {
return true;
}
const blob = freshPhoto.blob;
// Convert stored data (ArrayBuffer or legacy Blob) to a Blob for upload
const blob = Storage.getBlob(freshPhoto);
console.log('[SYNC] Uploading:', photo.filename,
'(' + (blob ? (blob.size / 1024 / 1024).toFixed(1) + 'MB' : 'no blob') + ')',
'attempt', retryCount + 1, 'of', this.MAX_RETRIES);
// Validate blob reference exists
if (!blob || !(blob instanceof Blob) || blob.size === 0) {
// Validate blob exists and has content
if (!blob || blob.size === 0) {
throw new Error('Photo data is missing or corrupted - please delete and re-capture');
}
// Actually try to read the blob to verify data is accessible
// (iOS Safari can evict blob data from IndexedDB while keeping the reference)
const readable = await this.validateBlobReadable(blob);
if (!readable) {
// Blob data is gone — no amount of retrying will fix this
console.error('[SYNC] Blob data is no longer readable:', photo.filename);
await Storage.updatePhoto(photo.id, {
status: 'failed',
lastError: 'Photo data was lost by the browser - please re-capture',
error: 'Photo data was lost by the browser - please re-capture'
});
return false;
}
await Storage.updatePhoto(photo.id, { status: 'uploading' });
// Prevent page navigation during upload
@@ -294,19 +281,6 @@ const Sync = {
}
},
async validateBlobReadable(blob) {
try {
// Try to read the first byte — if iOS has evicted the data,
// this will throw even though the Blob reference looks valid
const slice = blob.slice(0, 1);
const buf = await slice.arrayBuffer();
return buf.byteLength > 0;
} catch (e) {
console.error('[SYNC] Blob readability check failed:', e.message);
return false;
}
},
async checkFileExists(path) {
try {
const verifyUrl = '/api/files/verify?path=' + encodeURIComponent(path);