(** Resolution across a whole liturgical year (spec §2.4).

    Transfers make per-date resolution impossible to do correctly: resolving
    25 March can push a feast onto 26 March, and RG 97-98 has coinciding
    I-class feasts transfer in table order, which needs global knowledge of
    the whole year. So [year] is the primitive -- it resolves every date in
    one pass -- and [day] is derived: it finds the liturgical year containing
    a date and indexes into it. Both are pure; neither caches.

    This module resolves each day's temporal-vs-sanctoral contest but does
    not yet place deferred transfers (RG 96-98): a losing candidate the
    rite's rules send to [Precedence.Transfer] is not observed and not
    commemorated on the day it lost, and [transferred_in]/[transferred_out]
    both stay [None] everywhere -- but it is not silently dropped either. It
    lands in that day's [Liturgical_day.omitted] with the reason ["deferred:
    transfer placement not yet implemented (Task 6)"], alongside
    [Precedence]'s own native omissions (yielded to a higher day; admission
    limit reached), each with its own reason. Task 6 adds the fixed-point
    placement pass that actually places these; until then, this is the
    day's complete, honest accounting of what happened to every candidate. *)

(** [year rite layer y] resolves every day of the liturgical year that opens
    in civil year [y]: from [rite.year_start y] through the day before
    [rite.year_start (y + 1)], inclusive of both ends.

    Total over 1583..9999, including the boundary years:
    - At [y] = 9999, [rite.year_start (y + 1)] would ask for civil year
      10000, out of {!Date}'s domain (this is the bug Plan 2 shipped in
      [Validate] and later fixed). The end of the walk clamps to 31 December
      9999 instead of computing that call; the returned year comes back
      truncated to whatever the rite's own temporal cycle covers between
      [rite.year_start 9999] and the last day of that civil year, not
      un-computable.
    - Symmetrically, [y] < 1583 clamps the start of the walk to 1 January
      1583 instead of calling [rite.year_start y] on an out-of-domain civil
      year. [year] is never called this way directly by anything in this
      module; {!day} is the only caller that can reach [y] = 1582 (one below
      the floor, never lower), when the date it was asked about sits in civil
      year 1583 before that year's own [rite.year_start] -- i.e. the sliver
      whose true liturgical year opened in civil year 1582, which the domain
      cannot represent. Calling [year] with such a [y] directly is also safe:
      it returns exactly that truncated sliver. *)
val year : ('s, 'r) Rite.t -> 'r Layer.t -> int -> ('s, 'r) Liturgical_day.t array

(** [day rite layer date] finds the liturgical year containing [date] -- the
    year [y] with [rite.year_start y <= date < rite.year_start (y + 1)] --
    and returns its slot for [date]. Recomputes that whole year on every
    call: pure, no cache, no mutable state. Acceptable cost for the natural
    usage (dump a year, sweep years for validation), which pays it once. *)
val day : ('s, 'r) Rite.t -> 'r Layer.t -> Date.t -> ('s, 'r) Liturgical_day.t