(** The invariant harness -- validation layer 2. Checks run over a *liturgical*
    year, not a civil year: a season that straddles January would otherwise look
    as though it recurs. *)
type failure = { year : int; date : string; check : string; detail : string }

val failure_to_string : failure -> string

(** [run vocab ~year_start ~temporal ~anchors ~year] returns every invariant
    violation in the liturgical year opening in civil year [year]. An empty
    list means the year is clean.

    [anchors y] is the rite's own independent restatement of its fixed and
    Easter-derived named days for civil year [y], as (expected slug, date)
    pairs -- not derived from [temporal] itself, so a drift between the two
    is caught rather than invisible. [run] consults both [anchors year] and
    [anchors (year + 1)], since a liturgical year straddles two civil years,
    and checks only the pairs whose date actually falls within the year
    walked.

    Total over the whole 1583..9999 domain, including [year] = 9999: the
    liturgical year opening there continues into out-of-domain civil year
    10000, so the walk is clamped to 31 December 9999 and the checks run
    against that truncated final year rather than raising. *)
val run :
  ('s, 'r) Vocab.t ->
  year_start:(int -> Date.t) ->
  temporal:(Date.t -> ('s, 'r) Temporal.t) ->
  anchors:(int -> (string * Date.t) list) ->
  year:int ->
  failure list