Product Updates

Transcript API

• transcribeVideo(id, options?) — fetch captions for a single video without an API key
• transcribePlaylist(id, options?) — batch fetch transcripts for every video in a playlist
• listCaptionTracks(id) — discover available language tracks before downloading
• Output formatters: toSRT(), toVTT(), toPlainText()
• TranscriptClient — reusable client with shared config

Batch Transcript

• Configurable concurrency (1–20 workers) for parallel transcript fetching
• from / to range filtering to process a subset of the playlist
• onProgress callback for real-time progress tracking
• Partial failure handling — individual video failures are caught and recorded, not thrown
• Returns per-video results with status: "success" | "failed"

Caching

• InMemoryCache — process-only cache with TTL and size limits (~0.03ms hits)
• FsCache — filesystem persistence with JSON storage (~0.3ms hits)
• CacheStore interface for custom backends (Redis, etc.)
• Automatic cache key generation per video ID, language, and metadata flag

Retry & Resilience

• Exponential backoff retry for transient HTTP failures (429, 5xx)
• retries and retryDelay options on all transcript requests
• AbortSignal support to cancel in-flight retry loops

Comments API

• comments(videoId, opts?) — fetch all comment threads with auto-pagination
• topComments(videoId, limit?) — top comments sorted by relevance
• commentReplies(commentId) — fetch all replies to a specific comment
• commentsWithReplies(videoId) — threads + all replies in one call
• searchComments(videoId, query) — keyword search within comments
• commentStats(videoId, threads) — aggregate stats (unique authors, reply ratio, most liked)
• commentQuery(videoId) — fluent builder for filtering and slicing comments

Internationalization (i18n)

• regions(hl?) — list all supported YouTube regions (110+)
• languages(hl?) — list all supported languages (80+)
• videoCategoriesByRegion(regionCode, hl?) — fetch region-specific video categories
• Localized names via hl parameter (e.g., ja for Japanese)

REST API

• New endpoints: /api/comments/{videoId}, /api/comments/{videoId}/top, /api/comment-replies/{id}
• New endpoint: /api/transcript/{id} — single video transcript (no API key)
• New endpoint: /api/playlist/{id}/transcript — batch playlist transcript
• Removed URL utility endpoints (moved to standalone lyra-sdk/url subpath)

Framework Examples

• Added Hono, NestJS, and Next.js API server examples alongside Express
• API Reference now shows framework-specific code samples (Express, Hono, Next.js)

Playlist Query

• Added POST /api/playlist/{id}/query endpoint for filtering, sorting, and slicing playlist videos
• Filter by duration, views, and likes with min/max ranges
• Sort by views, likes, or duration in ascending or descending order
• Range parameter to paginate results (1-indexed start/end)

Video API

• getVideo(id) — fetch full video details by ID or URL
• getVideos(ids) — batch fetch multiple videos
• getVideoTitle(id) — lightweight title-only lookup (1 quota unit)

Channel API

• getChannel(id) — fetch channel metadata by ID, @username, or URL
• getChannelVideos(id, limit) — fetch recent uploads for a channel

Playlist API

• getPlaylist(id) — fetch complete playlist with all videos and total duration
• getPlaylistInfo(id) — playlist metadata only (1 quota unit)
• getPlaylistIds(id) — fetch all video IDs with auto-pagination

URL Utilities

• parseUrl(url) — parse a YouTube URL into a structured result
• extractUrl(url, type?) — extract video, playlist, or channel IDs from a URL

Express REST API

• Full REST API wrapper around all SDK functions
• Interactive OpenAPI documentation at /docs/api-reference
• Local development server via npm run dev:express