Session highlights

[wheresrhys]

A bit like the stats at the top of the page but more tailored

things such as

• we caught a bird that hasn't been seen for 2 years
• we caught more chiffs than in any other session [this year]
• ...

The rough high level product goal of this feature is "If you were gonna write an editorial describing the session... what would be in the standfirst/TLDR?"

As these are nice to have, not core data, and require comparing with other data across time they should be lazy loaded

[wheresrhys]

Implementation plan — shared design decisions

Work split into child issues (label ready), branches feature/219-session-highlights/<n>-<slug>. Only the final child's PR closes this issue.

Decisions (apply to all children)

1. Date-level only, not location-aware — SessionHighlights renders only when locationId === undefined.
2. One server action fetchSessionHighlights({ date, viewedGroupId }) in app/actions/session-highlights.ts, extended each increment; single Promise.all fan-out over RPCs. Uses getAuthenticatedSupabaseClient() + catchSupabaseErrors (pattern: app/actions/sp-data.ts).
3. Structured results, sentences in model — action returns SessionHighlight[] (discriminated union); pure functions in app/models/session-highlights.ts: getScopeFilters, pickBroadestScope, derive* per family, sortHighlights (priority: totals → since → species records → first-ever → long-absence → weight), buildHighlightSentence (exhaustive switch).
4. Viewed group's data only — shared data excluded. Every new RPC takes required ringing_group_filter bigint and filters both Encounters.ringing_group_id AND Sessions.ringing_group_id (pattern: metrics_by_period_and_species.sql). Integration tests assert GroupDataSharing data does not leak into comparisons.
5. RPC conventions (existing project patterns): supabase/schema/schemas/public/functions/<name>.sql, LANGUAGE plpgsql STABLE, SET search_path TO 'public','pg_catalog', GRANT anon/authenticated/service_role, no SECURITY DEFINER. Migrations via npm run db:schema:apply; npm run db:types after; types re-exported via app/models/db.ts.
6. Record scopes: all-time > any-{season} > this-year > this-{season}; broadest wins. Season months derived from the session date via getSeasonName/getSeasonMonths in app/models/seasons.ts (shared with home page).
7. Tie rule: strict beat = record. A tie counts only when scope is all-time AND the tied previous record is >1 year before the session — copy like "Heaviest Blue Tit for 4 years". RPCs return previous best value and date so the model can apply this.

Sentence copy

• "Busiest session ever — 74 birds" / "Busiest autumn session ever — …" / "Busiest session of 2024 — …" / "Busiest session this autumn — …"
• "Most varied session ever — 18 species" (same scope variants)
• "Record day for Reed Warbler — 12 caught, the most ever" / "…the most in any autumn" / "…the most in 2024" / "…the most this autumn"
• "First ever Firecrest for the group"
• "Robin ARRETRAP recaught after 2 years, 10 months away (last seen 20 Jun 2021)"
• "Heaviest Blue Tit ever weighed — 13.1g (previous record 13.0g)" / lightest equivalent
• All-time ties >1 year old: "Heaviest Blue Tit for 4 years — 13.1g" / "Busiest session for 3 years — 74 birds" / "Record-equalling day for Reed Warbler — 12 caught, most for 2 years"
• "Busiest session since 12 May 2023 — 41 birds" / "Quietest session since 14 Sep 2023 — 3 birds" / "Quietest session ever — 3 birds"

Out of scope

Net-round highlights (cross-session records need the 15-min-gap logic from app/models/session-chronology.ts in SQL) — follow-up issue to be created with the final child.