SubMiner/docs/architecture/stats-trends-data-flow.md

Stats Trends Data Flow

read_when: touching stats trend charts, changing stats API payloads, or debugging dashboard performance

Summary

Trend charts now consume one chart-oriented backend payload from /api/stats/trends/dashboard.

Why

• remove repeated client-side dataset rebuilding in TrendsTab
• collapse multiple network round-trips into one request
• keep heavy chart shaping close to tracker/query logic

Data Sources

• rollup-backed:
  • activity charts
  • cumulative watch/cards/tokens/sessions trends
  • per-anime watch/cards/tokens/episodes series
• session-metric-backed:
  • lookup trends
  • lookup rate trends
  • watch-time by day-of-week/hour
• vocabulary-backed:
  • new-words trend

Metric Semantics

• subtitle-count stats now use Yomitan merged-token counts as the source of truth
• tokensSeen is the only active subtitle-count metric in tracker/session/rollup/query paths
• no whitespace/CJK-character fallback remains in the live stats path

Contract

The stats UI should treat the trends payload as chart-ready data. Presentation-only work in the client is fine, but rebuilding the main trend datasets from raw sessions should stay out of the render path.

For session detail timelines, omitting limit now means "return the full retained session telemetry/history". Explicit limit remains available for bounded callers, but the default stats UI path should not trim long sessions to the newest 200 samples.