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backlog/tasks/task-6 - Split-renderer.ts-into-focused-modules.md

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+---
+id: TASK-6
+title: Split renderer.ts into focused modules
+status: To Do
+assignee: []
+created_date: '2026-02-11 08:20'
+labels:
+  - refactor
+  - renderer
+  - architecture
+milestone: Codebase Clarity & Composability
+dependencies:
+  - TASK-5
+references:
+  - src/renderer/renderer.ts
+priority: high
+---
+
+## Description
+
+<!-- SECTION:DESCRIPTION:BEGIN -->
+renderer.ts is 2,754 lines with 94 functions handling 6+ distinct concerns: subtitle rendering, invisible overlay positioning, 4 modal UIs (Jimaku, Kiku, RuntimeOptions, Subsync), event handlers, keyboard chord system, and platform-specific layout. 16+ module-level state variables track overlapping modal states.
+
+Proposed structure:
+```
+src/renderer/
+├── renderer.ts          (entry point, initialization, IPC listeners)
+├── state.ts             (centralized state object replacing 16+ scattered lets)
+├── subtitle-render.ts   (renderSubtitle, renderTokenized, renderCharLevel, renderPlain)
+├── positioning.ts       (applyInvisibleSubtitleLayoutFromMpvMetrics + helpers)
+├── modals/
+│   ├── jimaku.ts        (Jimaku download modal - lines 1097-1518)
+│   ├── kiku.ts          (Kiku field grouping modal - lines 1519-1702)
+│   ├── runtime-options.ts (Runtime options modal - lines 1247-1364)
+│   └── subsync.ts       (Subsync modal - lines 1387-1466)
+├── handlers/
+│   ├── keyboard.ts      (keydown handlers, chord system)
+│   └── mouse.ts         (drag, hover, click handlers)
+└── utils/
+    ├── dom.ts           (DOM element access with validation)
+    └── platform.ts      (isLinux/isMacOS detection, platform-specific helpers)
+```
+
+Note: The renderer runs in Electron's renderer process, so module bundling considerations (esbuild/webpack or Electron's native ESM) need to be evaluated.
+<!-- SECTION:DESCRIPTION:END -->
+
+## Acceptance Criteria
+<!-- AC:BEGIN -->
+- [ ] #1 renderer.ts reduced to <400 lines (init + IPC wiring)
+- [ ] #2 Each modal UI in its own module
+- [ ] #3 Positioning logic extracted with helper functions replacing the 211-line mega function
+- [ ] #4 State centralized in a single object/module
+- [ ] #5 Platform-specific logic isolated behind abstractions
+- [ ] #6 All existing functionality preserved
+<!-- AC:END -->