fix(overlay): show annotated subtitle hover affordance

backlog/tasks/task-302 - Add-visible-hover-affordance-for-annotated-subtitle-tokens.md

@@ -0,0 +1,53 @@
+---
+id: TASK-302
+title: Add visible hover affordance for annotated subtitle tokens
+status: Done
+assignee: []
+created_date: '2026-04-26 03:39'
+updated_date: '2026-04-26 03:40'
+labels:
+  - overlay
+  - subtitle
+  - ux
+dependencies: []
+priority: medium
+---
+
+## Description
+
+<!-- SECTION:DESCRIPTION:BEGIN -->
+Annotated subtitle tokens keep annotation colors on hover, but with transparent hover backgrounds there is no visible hover indication. Add a subtle affordance that preserves annotation color semantics.
+<!-- SECTION:DESCRIPTION:END -->
+
+## Acceptance Criteria
+<!-- AC:BEGIN -->
+- [x] #1 Annotated token hover keeps annotation color instead of switching to hover text color.
+- [x] #2 Annotated token hover has a visible indication when hover background is transparent.
+- [x] #3 Regression tests cover the hover CSS contract.
+<!-- AC:END -->
+
+## Implementation Plan
+
+<!-- SECTION:PLAN:BEGIN -->
+1. Add failing CSS contract test for annotated token hover affordance.
+2. Add brightness/saturation filter to annotated token hover CSS without changing annotation color.
+3. Add changelog fragment and run focused verification.
+<!-- SECTION:PLAN:END -->
+
+## Implementation Notes
+
+<!-- SECTION:NOTES:BEGIN -->
+Implemented option 1 from approved design: annotated subtitle word hover keeps annotation color and adds `filter: brightness(1.18) saturate(1.08)` for visible affordance when the hover background is transparent.
+
+Verification passed: `bun test src/renderer/subtitle-render.test.ts`; `bun run changelog:lint`.
+<!-- SECTION:NOTES:END -->
+
+## Final Summary
+
+<!-- SECTION:FINAL_SUMMARY:BEGIN -->
+Added a visible hover affordance for annotated subtitle tokens without changing annotation color semantics. Annotated word hover now applies a small brightness/saturation lift while retaining the existing background behavior, so transparent hover backgrounds still show feedback.
+
+Regression coverage updated in `src/renderer/subtitle-render.test.ts` to assert the hover filter is present and that hover color overrides are still absent for annotated tokens. Added changelog fragment `changes/302-annotated-hover-affordance.md`.
+
+Verification: `bun test src/renderer/subtitle-render.test.ts`; `bun run changelog:lint`.
+<!-- SECTION:FINAL_SUMMARY:END -->