StageActiveOnEvent — checks the candidate stage_id is linked to the
given event_id via stage_days. Covers performance create/update
(perf.event_id ↔ stage) and the timetable move endpoint
(target_stage_id ↔ resolved target event).
WithinEventBounds — checks a candidate datetime is inside the event's
[start_at, end_at] window. Used for performance start/end dates and
move-target dates against the relevant sub-event for festivals.
OptionExpiresInFuture — conditional rule fired only when
booking_status === 'option'. Asserts option_expires_at is set and in
the future. Implementation of RFC §10.1 transition gate at the
request layer (the service layer enforces the same invariant).
ContractRequiresFee — conditional rule fired only when
booking_status === 'contracted'. Asserts fee_amount is set and > 0.
Same dual-layer enforcement as OptionExpiresInFuture.
All four pass silently when the validated field is null or the
context is irrelevant — the FormRequest still owns the surrounding
required/nullable/exists rules.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
