chore(backlog): add mining workflow milestone and tasks

backlog/tasks/task-239.4 - Add-sentence-clipping-from-arbitrary-subtitle-ranges.md

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+---
+id: TASK-239.4
+title: Add sentence clipping from arbitrary subtitle ranges
+status: To Do
+assignee: []
+created_date: '2026-03-26 20:49'
+labels:
+  - feature
+  - subtitle
+  - anki
+  - ux
+milestone: m-2
+dependencies: []
+references:
+  - src/renderer/modals/subtitle-sidebar.ts
+  - src/main/runtime/subtitle-position.ts
+  - src/anki-integration/card-creation.ts
+  - src/main/runtime/mpv-main-event-actions.ts
+parent_task_id: TASK-239
+priority: medium
+---
+
+## Description
+
+<!-- SECTION:DESCRIPTION:BEGIN -->
+Current mining flows are optimized around the active subtitle line. Add a sentence-clipping workflow that lets users select an arbitrary contiguous subtitle range, preview the combined text/timing, and mine from that selection. This should improve multi-line dialogue capture without forcing manual copy/paste or separate post-processing.
+<!-- SECTION:DESCRIPTION:END -->
+
+## Acceptance Criteria
+
+<!-- AC:BEGIN -->
+- [ ] #1 Users can select a contiguous subtitle range from the existing subtitle UI instead of being limited to the active cue.
+- [ ] #2 The workflow previews the combined text and resulting timing range before mining.
+- [ ] #3 Mining from a clipped range uses the combined subtitle payload in card generation while preserving existing single-line behavior.
+- [ ] #4 The feature handles overlapping/edge timing cases predictably and does not corrupt the normal active-cue flow.
+- [ ] #5 Tests cover range selection, combined payload generation, and at least one card-creation path using a clipped selection.
+<!-- AC:END -->
+
+## Implementation Plan
+
+<!-- SECTION:PLAN:BEGIN -->
+1. Define a selection model that fits the existing subtitle sidebar/runtime data flow.
+2. Add preview + confirmation UI before routing the clipped payload into mining.
+3. Keep the existing single-line path intact and treat clipping as an additive workflow.
+4. Verify with subtitle-sidebar, runtime, and Anki/card-creation tests.
+<!-- SECTION:PLAN:END -->