gui-video-clipper/chat-summaries/2026-09-21_10-22-brainstorm-and-plan-video-clipper-summary.md

Video Clipper — Brainstorming & Implementation Plan

Date: 2026-09-21 10:22 Task: Brainstormed the design and wrote a comprehensive implementation plan for a macOS GUI video clipper app.

Task Description

Designed and planned a macOS GUI app ("Video Clipper") that lets users paste a YouTube URL, scrub a timeline, mark clip boundaries, and export clips — without manually downloading the video first. Like LosslessCut, but for online videos.

Changes Made

Design Spec (docs/superpowers/specs/2026-09-21-video-clipper-design.md)

• Brainstormed tech approach: chose Tauri v2 + Svelte 5 over Swift/SwiftUI and Python/Qt
• Defined architecture: Rust backend (subprocess orchestration), Svelte frontend (Canvas timeline), external CLI tools (ffmpeg, yt-dlp)
• Designed hybrid playback: stream immediately for preview, download in background for export
• Designed 4-layer Canvas timeline: thumbnails → waveform → clip markers → controls
• Researched YouTube 2026 auth landscape: cookies + PO Token + JS runtime required
• Added three features to MVP during review: waveform visualization, thumbnail strip, cookie/auth support
• Defined complete data model, keyboard shortcuts (NLE-style), export flow, edge cases

Implementation Plan (docs/superpowers/plans/2026-09-21-video-clipper.md)

12 tasks with TDD approach, exact file paths, complete code, and test code:

1. Project Scaffolding — Tauri v2 + Svelte 5 scaffold, plugins, layout shell, utility functions
2. Dependency Manager + Setup Wizard — Check ffmpeg/yt-dlp/deno/PO-token-plugin, guided install
3. Preferences Store — Cookie source (Firefox default), output directory, persistence
4. Video Resolver + URL Input + Video Player — yt-dlp metadata/stream URL, paste-to-play pipeline
5. Download Manager + Status Bar — Background yt-dlp download with progress channel
6. Timeline Core — Canvas renderer, coordinate mapping, playhead, scrub, zoom
7. Clip Management — I/O marking, clip CRUD store, timeline markers, draggable handles, ClipList
8. Transport Controls + Keyboard Shortcuts — All playback controls, J/K/L shuttle, all hotkeys
9. Keyframe Index — ffprobe extraction, keyframe/frame navigation
10. Waveform — ffmpeg audio peak extraction, Canvas rendering with zoom aggregation
11. Thumbnails — ffmpeg frame extraction, sprite sheets, adaptive-density Canvas rendering
12. Clip Export + Export Dialog — Lossless/precise/merged ffmpeg pipeline, full export UI

Key Decisions

• Tauri v2 + Svelte 5 chosen over Swift/SwiftUI for natural Canvas/timeline UI building
• Firefox cookies default — only browser where --cookies-from-browser reliably works in 2026
• bgutil-ytdlp-pot-provider plugin required for YouTube PO Token generation
• Tauri Channels (not events) for streaming progress data — strongly typed, optimized for throughput
• Static placeholder for waveform/thumbnails before download completes (not progressive)
• Sprite sheet approach for thumbnails to minimize image load overhead

Lessons Learned

• YouTube in 2026 requires a 3-part auth chain: cookies + PO Token provider plugin + JS runtime. Just --cookies-from-browser alone is insufficient.
• Chrome 127+ broke cookie decryption for external tools — Firefox is the only reliable browser for --cookies-from-browser.
• Tauri v2 Channels (tauri::ipc::Channel) are the recommended way to stream data from Rust→frontend, not the event system (which is JSON-only and not designed for throughput).
• yt-dlp -v with a URL shows [debug] Extractor Plugins: GetPOT to verify the PO token plugin is installed — there's no dedicated --list-plugins flag.

Follow-up Items

• Stream URL re-resolution on playback error (noted in plan self-review but not a dedicated task)
• Future features documented in spec: local file support, quality selection, save/load projects, batch processing, cross-platform