SubMiner/backlog/tasks/task-44 - Add-multi-window-subtitle-mode-for-secondary-monitor-display.md

id, title, status, assignee, created_date, labels, dependencies, priority

id	title	status	assignee	created_date	labels	dependencies	priority
TASK-44	Add multi-window subtitle mode for secondary monitor display	To Do		2026-02-14 02:15	feature renderer multi-monitor quality-of-life		low

Description

Support rendering the subtitle overlay on a secondary display at a larger, more readable size while the video plays full-screen on the primary monitor.

Motivation

For study-focused sessions, reading subtitles overlaid on video at normal size can cause eye strain. Users with multiple monitors would benefit from a dedicated subtitle display — larger font, clean background, with full tokenization and click-to-lookup functionality — while the video plays unobstructed on the main screen.

Features

1. Detached subtitle window: A second Electron BrowserWindow that mirrors the current subtitle content
2. Configurable placement: User selects which monitor and position for the subtitle window
3. Independent styling: The detached window can have different font size, background opacity, and layout than the overlay
4. Synchronized content: Both windows show the same subtitle in real-time
5. Lookup support: Yomitan click-to-lookup works in the detached window
6. Toggle: Shortcut to quickly enable/disable the secondary display

Technical considerations

• Electron supports multi-monitor via screen.getAllDisplays() and BrowserWindow bounds
• The detached window should receive subtitle updates via IPC from the main process (same path as the overlay)
• Overlay on the primary monitor could optionally be hidden when the detached window is active
• Window should remember its position across sessions (persist to config or state file)
• Consider whether the detached window should be always-on-top or normal

Acceptance Criteria

• #1 A detached subtitle window can be opened on a secondary monitor.
• #2 Subtitle content is synchronized in real-time between overlay and detached window.
• #3 Detached window has independently configurable font size and styling.
• #4 Yomitan word lookup works in the detached window.
• #5 Shortcut toggles the detached window on/off.
• #6 Window position is persisted across sessions.