SubMiner/backlog/tasks/task-202 - Use-ended-session-media-position-for-anime-episode-progress.md

id, title, status, assignee, created_date, updated_date, labels, milestone, dependencies, references, priority, ordinal

id	title	status	assignee	created_date	updated_date	labels	milestone	dependencies	references	priority	ordinal
TASK-202	Use ended session media position for anime episode progress	Done	Codex	2026-03-19 14:55	2026-03-19 17:36	stats ui bug	m-1		stats/src/components/anime/EpisodeList.tsx stats/src/types/stats.ts src/core/services/immersion-tracker/session.ts src/core/services/immersion-tracker/query.ts src/core/services/immersion-tracker/storage.ts	medium	105720

Description

The anime episode list currently computes the Progress column from cumulative totalActiveMs / durationMs, which can exceed the intended watch-position meaning after rewatches or repeated sessions. Persist the playback position at the time a session ends and drive episode progress from that stored stop position instead.

Acceptance Criteria

• #1 Session finalization persists the playback position reached when the session ended.
• #2 Anime episode queries expose the most recent ended-session media position for each episode.
• #3 Episode-list progress renders from ended media position instead of cumulative active watch time.
• #4 Regression coverage locks storage/query/UI behavior for the new progress source.

Implementation Plan

1. Add failing regression coverage for persisted ended media position and episode progress rendering.
2. Add ended_media_ms to the immersion-session schema and persist lastMediaMs when ending a session.
3. Thread the new field through episode queries/types and render episode progress from endedMediaMs / durationMs.
4. Run targeted verification plus typecheck, then record the outcome.

Outcome

Added nullable ended_media_ms storage to immersion sessions, persisted lastMediaMs when sessions finalize, and exposed the most recent ended-session media position through anime episode queries/types. The anime episode list now renders Progress from endedMediaMs / durationMs instead of cumulative active watch time, so rewatches no longer inflate the displayed percentage.

Verification:

• bun test src/core/services/immersion-tracker/storage-session.test.ts
• bun test src/core/services/immersion-tracker/__tests__/query.test.ts
• bun test stats/src/lib/yomitan-lookup.test.tsx stats/src/lib/stats-ui-navigation.test.tsx
• bun run typecheck
• bun run changelog:lint
• bun x prettier --check 'src/core/services/immersion-tracker/types.ts' 'src/core/services/immersion-tracker/storage.ts' 'src/core/services/immersion-tracker/session.ts' 'src/core/services/immersion-tracker/query.ts' 'src/core/services/immersion-tracker/storage-session.test.ts' 'src/core/services/immersion-tracker/__tests__/query.test.ts' 'stats/src/types/stats.ts' 'stats/src/components/anime/EpisodeList.tsx' 'stats/src/lib/yomitan-lookup.test.tsx' 'stats/src/lib/stats-ui-navigation.test.tsx' 'backlog/tasks/task-202 - Use-ended-session-media-position-for-anime-episode-progress.md' 'changes/2026-03-19-stats-ended-media-progress.md'
• bash .agents/skills/subminer-change-verification/scripts/verify_subminer_change.sh --lane core 'src/core/services/immersion-tracker/types.ts' 'src/core/services/immersion-tracker/storage.ts' 'src/core/services/immersion-tracker/session.ts' 'src/core/services/immersion-tracker/query.ts' 'src/core/services/immersion-tracker/storage-session.test.ts' 'src/core/services/immersion-tracker/__tests__/query.test.ts' 'stats/src/types/stats.ts' 'stats/src/components/anime/EpisodeList.tsx' 'stats/src/lib/yomitan-lookup.test.tsx' 'stats/src/lib/stats-ui-navigation.test.tsx' 'backlog/tasks/task-202 - Use-ended-session-media-position-for-anime-episode-progress.md' 'changes/2026-03-19-stats-ended-media-progress.md'
• Verifier artifacts: .tmp/skill-verification/subminer-verify-20260319-173511-AV7kUg/