kernel(validate): invariant harness over liturgical years

Coverage, season contiguity and completeness, Sunday-aligned week numbering,
slug well-formedness, weekday agreement and vocabulary closure.
Checks run over a liturgical year rather than a civil one, since Christmastide
straddles January and would otherwise appear to recur.

Run against EF temporal for landmark years, both Easter extremes, and 200
random years across 1583..9998 -- the property layer is how confidence reaches
past the oracle horizon.

1 files changed, 16 insertions, 0 deletions

diff --git a/lib/kernel/validate.mli b/lib/kernel/validate.mli
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+(** 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 ~year] returns every invariant violation in
+    the liturgical year opening in civil year [year]. An empty list means the
+    year is clean. *)
+val run :
+  ('s, 'r) Vocab.t ->
+  year_start:(int -> Date.t) ->
+  temporal:(Date.t -> ('s, 'r) Temporal.t) ->
+  year:int ->
+  failure list