fix(innertube): use musicAnimatedThumbnailRenderer backup for video covers

[kairosci]

Problem

Video covers served exclusively as animated thumbnails were rendered without a visible cover image throughout the app.

Cause

The ThumbnailRenderer data class parsed musicAnimatedThumbnailRenderer from the YouTube Music API response, but this field was never consulted when resolving thumbnail URLs. Every call site accessed only musicThumbnailRenderer, so animated thumbnails with no static equivalent were silently dropped.

Solution

This commit adds a top-level getThumbnailUrl() function to ThumbnailRenderer that falls through musicThumbnailRenderer, then musicAnimatedThumbnailRenderer.backupRenderer, then croppedSquareThumbnailRenderer. All seventy-seven existing call sites have been migrated from the manual musicThumbnailRenderer?.getThumbnailUrl() pattern to the new unified method, ensuring that the YouTube-provided static fallback inside animated thumbnails is always used.

Testing

Verified that thumbnail images now appear for previously broken video covers across home, library, search, history, album, playlist, podcast, artist, and related content pages.

Related Issues

Closes #4033

Summary by CodeRabbit

• Bug Fixes
  • Improved thumbnail loading across search, library, home, artist, album, playlist, podcast, history, and related views.
  • More items now display artwork consistently, including songs, albums, playlists, artists, episodes, and podcasts.
  • Added broader fallback handling so thumbnails are less likely to appear missing or blank.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 725c2239-6cfd-41f4-a0ff-6a8aedb74bcd

📥 Commits

Reviewing files that changed from the base of the PR and between 3889662 and afa1d00.

📒 Files selected for processing (1)

• innertube/src/main/kotlin/com/metrolist/innertube/models/ThumbnailRenderer.kt

💤 Files with no reviewable changes (1)

• innertube/src/main/kotlin/com/metrolist/innertube/models/ThumbnailRenderer.kt

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📝 Walkthrough

Walkthrough

Adds a getThumbnailUrl() helper to ThumbnailRenderer and updates thumbnail extraction across YouTube.kt and innertube page parsers to call it instead of directly traversing musicThumbnailRenderer.

Changes

Thumbnail Extraction Refactor

Layer / File(s)	Summary
ThumbnailRenderer fallback helper innertube/.../models/ThumbnailRenderer.kt	Adds getThumbnailUrl(): String? and removes serialization-specific annotations/imports around the mapping.
YouTube.kt episode/song parsing innertube/.../YouTube.kt	podcastWithDebug, convertToChartItem, convertMusicTwoRowItem, newEpisodes (shelf and carousel), episodesForLater, and continueListening now use the helper.
Album, Artist item/page parsers innertube/.../pages/AlbumPage.kt, ArtistItemsPage.kt, ArtistPage.kt	Thumbnail derivation for songs, albums, playlists, artists, episodes, and podcasts switched to getThumbnailUrl().
History, Home, Library pages innertube/.../pages/HistoryPage.kt, HomePage.kt, LibraryAlbumsPage.kt, LibraryPage.kt	Responsive-list and two-row item builders updated to call getThumbnailUrl() across multiple item types.
New release, Playlist, Podcast, Related pages innertube/.../pages/NewReleaseAlbumPage.kt, PlaylistPage.kt, PodcastPage.kt, RelatedPage.kt	Thumbnail assignment for songs, albums, playlists, artists, episodes, and podcasts switched to the new helper.
Search pages innertube/.../pages/SearchPage.kt, SearchSuggestionPage.kt, SearchSummaryPage.kt	All result-type branches updated to derive thumbnails via getThumbnailUrl().

Estimated code review effort: 2 (Simple) | ~12 minutes

Possibly related PRs

• MetrolistGroup/Metrolist#4025: Both PRs modify episode parsing logic in YouTube.kt, overlapping on newEpisodes() and episodesForLater() item-creation paths.

Suggested reviewers: nyxiereal

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly matches the core change: adding animated-thumbnail fallback for video covers.
Description check	✅ Passed	The description follows the template and includes problem, cause, solution, testing, and related issue details.
Linked Issues check	✅ Passed	The changes resolve #4033 by falling back to animated thumbnail backups so music video covers render when static thumbnails are absent.
Out of Scope Changes check	✅ Passed	The PR stays focused on thumbnail resolution and related parsing cleanup, with no clear unrelated changes.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@innertube/src/main/kotlin/com/metrolist/innertube/pages/HistoryPage.kt`:
- Line 63: The `ThumbnailRenderer` model has a serial name collision because
`musicThumbnailRenderer` is aliased to `croppedSquareThumbnailRenderer`, which
conflicts with another property using the same effective serialized name. Update
the serialization mapping in the `ThumbnailRenderer` class by removing that
alias or renaming the conflicting property so each field has a unique serial
name and decoding can succeed.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 453d35d2-54e6-42d3-9cff-b15381971170

📥 Commits

Reviewing files that changed from the base of the PR and between 1132598 and 3889662.

📒 Files selected for processing (16)

• innertube/src/main/kotlin/com/metrolist/innertube/YouTube.kt
• innertube/src/main/kotlin/com/metrolist/innertube/models/ThumbnailRenderer.kt
• innertube/src/main/kotlin/com/metrolist/innertube/pages/AlbumPage.kt
• innertube/src/main/kotlin/com/metrolist/innertube/pages/ArtistItemsPage.kt
• innertube/src/main/kotlin/com/metrolist/innertube/pages/ArtistPage.kt
• innertube/src/main/kotlin/com/metrolist/innertube/pages/HistoryPage.kt
• innertube/src/main/kotlin/com/metrolist/innertube/pages/HomePage.kt
• innertube/src/main/kotlin/com/metrolist/innertube/pages/LibraryAlbumsPage.kt
• innertube/src/main/kotlin/com/metrolist/innertube/pages/LibraryPage.kt
• innertube/src/main/kotlin/com/metrolist/innertube/pages/NewReleaseAlbumPage.kt
• innertube/src/main/kotlin/com/metrolist/innertube/pages/PlaylistPage.kt
• innertube/src/main/kotlin/com/metrolist/innertube/pages/PodcastPage.kt
• innertube/src/main/kotlin/com/metrolist/innertube/pages/RelatedPage.kt
• innertube/src/main/kotlin/com/metrolist/innertube/pages/SearchPage.kt
• innertube/src/main/kotlin/com/metrolist/innertube/pages/SearchSuggestionPage.kt
• innertube/src/main/kotlin/com/metrolist/innertube/pages/SearchSummaryPage.kt