feat(schedule): add configurable day-start hour

[chiptus]

Adds festivals.day_start_hour (0-23, default 0) so a festival can fold post-midnight sets into the previous festival day instead of always splitting at exact midnight. Widens the existing day-key seam (getFestivalDayKey/formatDayOnly) and threads the cutoff through schedule grouping, the day filter, the days reveal level, and the horizontal timeline's day boundaries/jump targets.

Closes #86

Verification

• Set a festival's day-start hour to 0 (default): schedule list, timeline, day filter, and reveal-level day labels render identically to before.
• Set a festival's day-start hour to 6 in the festival edit dialog: a ~02:00 set moves under the previous festival day in both the list and the horizontal timeline; the day filter and the days-reveal display agree; the day header reads the previous date.
• Confirm the day filter dropdown offers the shifted day as an option (not just the edition's raw calendar-date range).
• pnpm run typecheck, pnpm run lint, pnpm exec vitest run, and pnpm run build all pass.

Note: the issue's spec mentioned following "the existing react-hook-form pattern" in the festival edit dialog, but that dialog (FestivalDialog.tsx) actually uses plain useState, not react-hook-form — the new field follows the file's actual existing pattern instead.

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Project	Deployment	Actions	Updated
upline	Ready	Preview	Oct 15, 2026 7:57am UTC

[github-actions]

Deploy → staging — workflow run
Last updated: 2026-10-15 07:58:52 UTC

• ✅ DB migrations succeeded
• ✅ Edge functions succeeded
• ⏭️ Type generation skipped (no changes)

[Copilot]

🟡 Changes recommended

The current dayStartHour implementation in src/lib/timeUtils.ts shifts instants in UTC before timezone formatting, which can misclassify festival days around DST transitions.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

Adds a per-festival day_start_hour cutoff (defaulting to midnight) so post-midnight sets can be grouped/labelled under the previous “festival day”, and threads that cutoff through schedule grouping, day filtering, reveal-level day labels, and the horizontal timeline’s day boundaries/jump behavior.

Changes:

• Adds festivals.day_start_hour (0–23, default 0) to the database schema and Supabase generated types, and wires it into festival create/update flows and the admin festival edit dialog.
• Extends the “festival day key” seam (getFestivalDayKey / formatDayOnly) and propagates dayStartHour through schedule list/timeline grouping, timeline geometry/boundaries/jump targets, and active-day detection.
• Reworks day-filter option generation to include a leading shifted day when a cutoff is configured, and adds unit tests across the updated time/day utilities.

File summaries

File	Description
supabase/migrations/20260829160000_add_festival_day_start_hour.sql	Adds day_start_hour column + range check constraint on festivals.
src/routes/festivals/$festivalSlug/editions/$editionSlug/schedule/timeline.tsx	Passes festival.day_start_hour into schedule/timeline data and container.
src/routes/festivals/$festivalSlug/editions/$editionSlug/schedule/list.tsx	Threads dayStartHour through list schedule grouping and memo deps.
src/pages/SetDetails/SetInfoCard.tsx	Uses formatDayOnly(..., day_start_hour) for reveal-level day display.
src/pages/SetDetails/NonMusicSetDetail/NonMusicSetBanner.tsx	Uses formatDayOnly(..., day_start_hour) for reveal-level day display.
src/pages/SetDetails/MultiArtistSetInfoCard.tsx	Uses formatDayOnly(..., day_start_hour) for reveal-level day display.
src/pages/EditionView/tabs/VoteTab/SetCard/SetMetadata.tsx	Uses formatDayOnly(..., day_start_hour) for reveal-level day display.
src/pages/EditionView/tabs/ScheduleTab/horizontal/timeScaleGeometry.ts	Makes date-change detection use festival-day keys with dayStartHour.
src/pages/EditionView/tabs/ScheduleTab/horizontal/timeScaleGeometry.test.ts	Adds unit test for cutoff folding behavior in date-change detection.
src/pages/EditionView/tabs/ScheduleTab/horizontal/TimeScaleContainer.tsx	Adds dayStartHour prop and passes it to TimeScale.
src/pages/EditionView/tabs/ScheduleTab/horizontal/TimeScale.tsx	Passes dayStartHour to computeDateChanges.
src/pages/EditionView/tabs/ScheduleTab/horizontal/TimelineToolbar.tsx	Threads dayStartHour into day jump controls.
src/pages/EditionView/tabs/ScheduleTab/horizontal/TimelineOverview.tsx	Threads dayStartHour into day-boundary calculation.
src/pages/EditionView/tabs/ScheduleTab/horizontal/TimelineContainer.tsx	Adds dayStartHour prop and threads into scroll sync / overview / scale.
src/pages/EditionView/tabs/ScheduleTab/horizontal/DayJumpButtons.tsx	Passes dayStartHour into getDayJumpMoment.
src/pages/EditionView/tabs/ScheduleTab/DayFilterSelect.tsx	Switches to buildDayFilterOptions(...) and includes festival cutoff.
src/pages/admin/festivals/FestivalDialog.tsx	Adds admin UI input for day_start_hour with clamping (0–23).
src/lib/timeUtils.ts	Extends festival-day key/label utilities and introduces festivalDayStart.
src/lib/timeUtils.test.ts	Adds tests for cutoff behavior in getFestivalDayKey and formatDayOnly.
src/lib/timelineOverviewGeometry.ts	Uses festivalDayStart for boundary placement with cutoff support.
src/lib/timelineOverviewGeometry.test.ts	Adds/updates tests for cutoff-aware boundary placement.
src/lib/timelineMountMoment.ts	Makes timeline mount moment resolve day-start using cutoff-aware boundary.
src/lib/timelineMountMoment.test.ts	Adds tests for cutoff-aware mount moment behavior.
src/lib/timelineDayJump.ts	Makes day jump fallback use cutoff-aware day start instead of midnight.
src/lib/timelineDayJump.test.ts	Adds test for cutoff-aware day jump fallback.
src/lib/dayFilterOptions.ts	New helper to build day-filter options, adding leading shifted day if needed.
src/lib/dayFilterOptions.test.ts	Unit tests for new day-filter option builder behavior.
src/integrations/supabase/types.ts	Updates generated DB types to include festivals.day_start_hour.
src/hooks/useTimelineScrollSync.ts	Threads dayStartHour into timeline mount-moment resolution.
src/hooks/useScheduleData.ts	Uses cutoff-aware festival day keys when grouping sets into schedule days.
src/hooks/useActiveTimelineDay.ts	Uses cutoff-aware day jump moments when computing active day offsets.
src/api/festivals/useUpdateFestival.ts	Allows updating day_start_hour via mutation typing.
src/api/festivals/useCreateFestival.ts	Allows setting day_start_hour on create via mutation typing.
docs/adr/0002-festival-timezone-display.md	Updates ADR to reflect the now-implemented configurable cutoff.

Review details

Suppressed comments (1)

src/lib/timeUtils.ts:208

• dayStartHour is defined in the festival's timezone, but the current implementation shifts the UTC instant with subHours before formatting in the target timezone. Around DST transitions this can produce the wrong festival-day key (e.g., after a spring-forward, subtracting N hours in UTC can subtract N±1 hours in local time), misgrouping sets and timeline day boundaries.

// festival's day rather than the viewer's. `dayStartHour` (0-23, the
// festival's configured day-start cutoff) shifts the instant back by that
// many hours first, so sets before the cutoff fold into the previous
// festival day instead of splitting at exact midnight.

• Files reviewed: 34/34 changed files
• Comments generated: 1
• Review effort level: Lite

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[github-actions]

Playwright test results

 68 passed

Details

 68 tests across 22 suites
 1 minute, 31 seconds
 1c8b53a

[chiptus]

Merged main in to resolve a conflict in list.tsx — main's day-grouping refactor (using filterScheduleDays/scheduleDays[].date) already produces the cutoff-aware day key via useScheduleData's internal getFestivalDayKey(..., dayStartHour), so this branch's now-redundant manual re-grouping block (using getFestivalDayKey directly on each slot) was dropped in favor of main's simpler version; also dropped the now-unused festival.day_start_hour dep the lint step flagged. pnpm run lint, pnpm run build:dev, and pnpm test all pass locally after the merge.

The Require staging label for migrations check is still red — this PR touches supabase/migrations/** and needs the staging label to pass that gate. The staging label is off-limits for the agent pipeline to apply, so this is waiting on you to add it before merge.

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Generated by Claude Code

[Copilot]

🟡 Changes recommended

Day grouping remains inconsistent in the fallback lineup and timeline labels, and the UTC subtraction misclassifies cutoff boundaries across DST transitions.

4 open findings

• Use computed festival-day key for timeline band labels · New
• Include festival cutoff in fallback lineup grouping config · New
• Use react-hook-form and validate day_end_hour from 0 to 23 · New
• Add integration coverage for day_end_hour persistence · New

1 resolved since last review

• formatDayOnly uses the same UTC subHours shifting as getFestivalDayKey, which can yield…

🧠 Review effort: Balanced