Media Library: retry thumbnail loads on failure (V1)#25785
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Whitespace and line-wrapping only, no behavior change. Split from the retry change so the logic diff reviews cleanly.
The media library cell gave up after a single failed thumbnail download, leaving a blank placeholder until the cell was scrolled off-screen and reconfigured. Transient failures (network blips, a CDN 5xx, a truncated response that fails to decode) are common, so one failure presented as a permanently missing thumbnail. SiteMediaCollectionCellViewModel now retries the load up to retryCount times (default 3, configurable via init) with exponential backoff (0.5s/1s/2s, capped at 8s). Cancelled requests -- cell scrolled away, deinit, prefetch cancelled -- neither retry nor report a failure.
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Generated by 🚫 Danger |
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| App Name | WordPress | |
| Configuration | Release-Alpha | |
| Build Number | 33169 | |
| Version | PR #25785 | |
| Bundle ID | org.wordpress.alpha | |
| Commit | a4337d7 | |
| Installation URL | 6g8e5lks297s0 |
Contributor
|
| App Name | Jetpack | |
| Configuration | Release-Alpha | |
| Build Number | 33169 | |
| Version | PR #25785 | |
| Bundle ID | com.jetpack.alpha | |
| Commit | a4337d7 | |
| Installation URL | 1i2s1b5j7ri90 |
P2 (WP-for-Teams) blogs report `isPrivate == false`, so media thumbnails were routed through Photon (a public image CDN) with no auth token, which returns 403 for the private originals. Treat WP-for-Teams blogs as private for media hosting so they skip Photon and send the bearer token.
Thumbnail load failures were silently swallowed, which made issues like the private-P2 403s impossible to diagnose from logs. Capture the requested URL, the routing flags that produced it, and the underlying error on failure (`.error`), plus the resolved load source per thumbnail (`.debug`).
A fatal client error (a 4xx such as 403 or 404) won't recover on retry, so give up immediately instead of spending the retry budget on it. 408 (timeout) and 429 (rate limited) are transient and keep retrying with backoff.
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Description
Fixes a bug where images intermittently fail to load in the Media Library (the V1 / UIKit grid — the one that ships in Release).
SiteMediaCollectionCellViewModelgave up after a single failed thumbnail download, leaving a blank grey placeholder until the cell was scrolled off-screen and reconfigured. Transient failures — a network blip, a CDN 5xx, a truncated response that fails to decode, or a request cancelled by fast scrolling — are common, so one failure presented as a permanently missing thumbnail.Root Cause
SiteMediaCollectionCellViewModel.fetchThumbnailIfNeeded()ran the load exactly once; on any error it calleddidFinishLoading(with: nil)— no retry, no error affordance. Because a failed load renders identically to the loading placeholder, the cell just stays grey. The only recovery path was cell reuse: scroll the cell away and back →configure→ refetch.Fix
The load task is now a retry loop:
retryCount: Int = 3— newinitparameter, so it's configurable. Default is 3 retries after the initial attempt (4 attempts total).Task.isCancelled(cell scrolled away,deinit, prefetch cancelled) the loop returns immediately: no retry, no failure state, no wasted downloads. The final give-up behavior is unchanged (didFinishLoading(with: nil)).Because each retry re-enters
MediaImageService.image(for:)— which re-checks the memory → disk → local-thumbnail chain — a retry also naturally picks up a local thumbnail or cache entry that became available in the meantime.Split into two commits — a
swift-formatpass on the file, then the retry logic — so the behavioral change reviews cleanly.Scope: V1 only, as a first step. The V2 SwiftUI grid (
WordPressMediaLibrary, behindFeatureFlag.mediaLibraryV2, debug-only) has related gaps — it passes noMediaHostfor auth, and renders a failed download as the loading placeholder — that are a separate effort. The V1 detail/preview (SiteMediaImageLoadingController) shares the same no-retry gap and is also left for follow-up.Testing instructions
Note
Draft: compiles locally —
WordPressscheme builds for the iOS Simulator (** BUILD SUCCEEDED **), andswift-format+ SwiftLint pass. Still pending on-device testing of the failure/retry path.