2026-03-21 — Features Not Yet Implemented (Comprehensive HTML/TXT Backlog)

PURPOSE AND USAGE
- This is a deliberately oversized working backlog and note-to-self document for future implementation planning, handoffs, Claude/ChatGPT coordination, regression awareness, and architecture memory.
- It is intentionally broader than a normal milestone list and should include speculative, defensive, UX, architectural, operational, and documentation gaps.
- The canonical filenames going forward are 2026-03-21-features-not-yet-implemented.txt and 2026-03-21-features-not-yet-implemented.html, with later dates replacing the leading date while keeping the same suffix.

CORE ARCHITECTURE BACKLOG
- Centralized state store for grid, selected tile, playback focus, overlays, and modal state.
- Formal panel lifecycle model: create, mount, activate, blur, suspend, unmount, destroy.
- Event bus or typed message layer for inter-panel communication.
- Deterministic async render pipeline with cancellation and stale-request protection.
- Config schema validation for window.MyAnythingListConfig and playlist-derived overrides.
- Backward compatibility map for older command syntaxes and legacy playlists.
- Plugin-style panel type registry instead of hardcoded type branching.
- Persistent session restore across reloads for layout and source state.
- Full cleanup discipline for iframes, timers, observers, object URLs, and event listeners.
- Predictable source-of-truth policy for config, query params, playlist commands, and runtime UI edits.

PLAYLIST AND COMMAND SYSTEM
- Formal command grammar for #_LoadLinkedImage, #_ReplaceThumbnailWithImage, fit options, future commands, comments, and escaping.
- Robust parser that accepts whitespace variation, quoted and safely unquoted forms where allowed, trailing comments where safe, and future extensibility.
- Validation and diagnostics for malformed commands, unknown directives, orphaned thumbnail commands, and dead URLs.
- Command reference generator extracted from live parser behavior.
- Playlist include/import capability for modular lists.
- Variables, aliases, macros, and reusable named blocks.
- Conditional commands based on output mode, language, orientation, or deployment target.
- Playlist lint mode with line-numbered warnings and suggested fixes.
- Round-trip-safe editor formatting so save/reload preserves intent.

LINKED-IMAGE AND THUMBNAIL SYSTEM
- Unified custom thumbnail pipeline so all replacement modes share one canonical code path.
- Guaranteed initial-load application of command-driven thumbnails before and after rebuilds.
- Retry and fallback policy for image load failures.
- Explicit local image path support relative to the playlist or HTML file.
- Per-image fit policy standardization with FIT_WIDTH, FIT_HEIGHT, FIT_ALL, contain, and cover mapped consistently.
- Image preloading heuristics for visible tiles and adjacent tiles.
- Broken-image visual placeholder and diagnostics.
- Download/export path that preserves custom thumbnail art exactly as shown.
- Domain-aware image loading diagnostics for headers, redirects, content type, and content disposition issues.

YOUTUBE AND MEDIA PANELS
- Centralized inline YouTube player manager.
- Formal focus enter/exit handoff between inline player, tile, and grid.
- Pause/resume behavior when navigation leaves a tile.
- Policy for when to preserve, blur, or destroy embeds.
- Support for additional providers such as Vimeo or direct MP4.
- Audio-only and low-bandwidth modes.
- Media error overlays and retry controls.
- Background preload and thumbnail extraction policy.

INPUT, FOCUS, AND NAVIGATION
- Global focus graph for keyboard, remote-control arrows, mouse, touch, and accessibility paths.
- No orphaned interactive surface after DOM mutation or iframe removal.
- Declarative pointer-event ownership for tiles, overlays, and media embeds.
- Improved tab order, focus ring visibility, and aria semantics.
- Long-press, hover-preview, and gesture support.
- Navigation history between panels and between playlist states.
- Configurable remote-control behavior for TV installations.

LOCAL FILESYSTEM AND SOURCE LOADING
- Best-possible sibling-file loading under file:// with honest failure reporting.
- Optional helper launcher or desktop wrapper for guaranteed local directory access when browser policy blocks it.
- Source labeling that always reveals the true loaded source.
- Cache-busting and freshness controls for remote text playlists.
- Staleness diagnostics when a remote source is unexpectedly cached by browser, CDN, or proxy.
- Optional source hash display for trust and comparison.
- Import-from-directory workflow for local bundles of playlist plus images plus docs.

UI AND EXPERIENCE BACKLOG
- Theming system and design tokens.
- Mobile-first responsive polish and tablet-specific modes.
- Improved empty-state guidance on first run.
- Visual diagnostics mode for tile data, source labels, and panel state.
- User-facing logs with filters and severity levels.
- Search, filter, tag, and favorites support.
- Panel grouping, pinning, and saved layouts.
- Animation system with reduced-motion support.

DOCUMENTATION AND HANDOFF BACKLOG
- Canonical HTML version of the features-not-yet-implemented document, not only TXT.
- Canonical TXT and HTML backlog docs should both be maintained in dated form.
- Docs index should link directly to the current backlog TXT and backlog HTML artifacts.
- Change log discipline for every daily build and every docs zip.
- Troubleshooting guide for local file launches, stale remote playlists, and image-command regressions.
- Spec cross-links between runtime behavior and documentation sections.
- Known limitations section explicitly separating browser security limits from app bugs.

TESTING AND REGRESSION BACKLOG
- Regression tests for local-first loading, explicit remote loading, linked-image commands, YouTube focus handoff, and export behavior.
- Sample canonical playlists for image-command coverage.
- Cross-browser smoke tests for Chrome, Edge, Safari, Firefox, Android WebView, and iPad.
- Regression snapshots for first-run local launch behavior.
- Automated checks for stale build labels and filename/version mismatches.
- Fixtures covering Unicode, special characters, and odd punctuation in playlists and filenames.

OPERATIONAL AND DEPLOYMENT BACKLOG
- Explicit distinction between canonical dated build file and deployment alias.
- Packaging standard for daily build folder contents.
- CDN and cache invalidation guidance.
- Build manifest with hashes.
- Environment banner for local/staging/live.
- Operational notes for S3 and CloudFront response headers affecting images and text playlists.

HIGH-PRIORITY UNRESOLVED ITEMS TO REMEMBER
- Anything that can leave stale pointer ownership or stale focus after embed teardown.
- Anything that can make a remote playlist appear stale due to hidden caching or proxy substitution.
- Anything that makes command-driven thumbnails fail silently.
- Anything that causes the local first-run experience to look broken even when the browser is the blocker.
- Anything that obscures the true source of currently loaded data.