fix: require a DIFFERENT recipe component to cover a per-code gap

.recipe_coverage()'s covered_years were computed once per recipe as a
union across ALL of its components (aggregate rows included), without
excluding the component currently being tested for a gap. So a code
whose only representation in a year was its own wide-era aggregate row
satisfied its own "covered" check -- self-coverage, not the "other
components" review-doc 0.3's criterion actually specifies ("...has no
rows ... but other components do").

.recipe_coverage() now returns (recipe_id, component_code, year)
triples instead of collapsing across components, and
.recipe_component_gapped() excludes the component under test before
checking coverage, so a gap only fires when a genuinely different
sibling component has data in that year.

Adds the boundary test this gap in coverage let slip through untested:
Broward FY2011 alone, where E05/F05/G05 each report solely as their own
wide-era aggregate row and E04/F04/G04 don't exist as codes before 2012
corpus-wide, so none of the three Corrections recipes have any OTHER
component to cover them -- must produce zero suggestions. The existing
2011-2012 combined test still passes, now firing because of the 2012
E05-gapped/E04-covers pair rather than 2011's self-coverage. Updates the
header comment to state the other-component requirement explicitly.

R/suggestions.R

@@ -20,21 +20,27 @@
 # EACH recipe component that is itself a category member individually,
 # rather than asking whether the whole category *result* has zero rows
 # that year. A recipe fires when one of its own components has zero rows
-# for this government in a requested year the recipe's own generic join
-# (same join .run_recipe() uses, aggregate rows included) otherwise covers
-# -- even if OTHER, unrelated codes in the same category have full data
-# that year and the overall result looks complete. That is a deliberate
-# narrowing of the R2-era false-positive guard: most governments don't use
-# every sibling code in a multi-code category every year, and per-code
-# detection WILL flag some of that as a "gap" even though it's really just
-# a government not having that particular sub-type of spending, not a
-# format-boundary artifact. The remaining guard against ordinary reporting
-# variance is the per-government `covered` check below (a component is
-# only flagged when the recipe's OWN join -- not some unrelated code --
+# for this government in a requested year, AND SOME OTHER component of that
+# SAME recipe -- excluding the gapped one itself -- has a row (same join
+# .run_recipe() uses, aggregate rows included) for that year. This is the
+# literal review-doc § 0.3 criterion: "...has no rows ... but other
+# components do." A component's OWN aggregate-only row does not satisfy
+# its own gap (self-coverage is not "other components"); only a genuinely
+# different sibling component can. This fires even if OTHER, unrelated
+# codes in the same category have full data that year and the overall
+# result looks complete. That is a deliberate narrowing of the R2-era
+# false-positive guard: most governments don't use every sibling code in a
+# multi-code category every year, and per-code detection WILL flag some of
+# that as a "gap" even though it's really just a government not having
+# that particular sub-type of spending, not a format-boundary artifact.
+# The remaining guard against ordinary reporting variance is the
+# per-government, per-OTHER-component `covered` check below (a component
+# is only flagged when a DIFFERENT component of the SAME recipe -- not
+# some unrelated code, and not the gapped component's own aggregate row --
 # actually has something to offer in that year); it no longer tries to
 # avoid noise from sibling *codes*, only from a recipe with genuinely
-# nothing to contribute. The acceptable noise level this trade produces is
-# a product decision, measured (not tuned here) by
+# nothing else to contribute. The acceptable noise level this trade
+# produces is a product decision, measured (not tuned here) by
 # data-raw/measure_signposting_rate.R and ruled on at Checkpoint R3.
 
 #' Recipe components that are classified under the requested category --
@@ -93,19 +99,21 @@
   ))
 }
 
-#' Which (recipe_id, year) pairs the recipe's own generic join actually
-#' covers for these governments -- the same join .run_recipe() uses
-#' (component year_min/year_max + gov_type_scope, no is_aggregate filter),
-#' just checking existence instead of summing. This is the per-government,
-#' whole-recipe guard against ordinary reporting variance: unlike
-#' .component_presence(), it is aggregate-inclusive and unioned across ALL
-#' of a recipe's components, not just the one requested code being tested,
-#' so a recipe with genuinely nothing to offer (no component, aggregate or
-#' leaf, has ever reported) never fires.
+#' Which (recipe_id, component_code, year) triples have at least one row
+#' (aggregate rows included) for these governments -- the same scoping
+#' .run_recipe()'s join uses (component year_min/year_max + gov_type_scope),
+#' just checking existence instead of summing. Kept at per-component grain
+#' (not unioned across the whole recipe, unlike the R2/R3-pre-fix version of
+#' this function) so a gap check can require the covering evidence to come
+#' from a DIFFERENT component -- review-doc § 0.3's "other components", not
+#' the gapped component's own aggregate row. This is the per-government
+#' guard against ordinary reporting variance: a recipe with genuinely
+#' nothing to offer from any OTHER component (aggregate or leaf) never
+#' fires.
 #' @noRd
 .recipe_coverage <- function(con, candidates, govid, years_lit) {
   DBI::dbGetQuery(con, sprintf(
-    "SELECT DISTINCT r.recipe_id, l.year
+    "SELECT DISTINCT r.recipe_id, r.component_code, l.year
      FROM long l
      JOIN harmonization_recipes r
        ON l.item_code = r.component_code
@@ -121,23 +129,29 @@
 }
 
 #' TRUE if recipe `rid` has at least one requested component with an
-#' in-scope requested year that has no data (`present`), in a year the
-#' recipe's own generic join is otherwise fillable (`covered`) -- the
-#' per-code gap the R2 whole-result check couldn't see.
+#' in-scope requested year that has no data (`present`), in a year some
+#' OTHER component of the same recipe is otherwise fillable (`covered`,
+#' excluding the component under test) -- the per-code gap the R2
+#' whole-result check couldn't see, covered by another component the way
+#' review-doc § 0.3 specifies (not by the gapped component's own aggregate
+#' row -- that is self-coverage, not "other components", and must not
+#' count).
 #' @noRd
 .recipe_component_gapped <- function(rid, requested, present, covered, years) {
-  covered_years <- covered$year[covered$recipe_id == rid]
-  if (length(covered_years) == 0L) return(FALSE)
-
   comps <- requested[requested$recipe_id == rid, , drop = FALSE]
   for (i in seq_len(nrow(comps))) {
+    this_code <- comps$component_code[i]
     in_scope <- years[years >= comps$year_min[i] & years <= comps$year_max[i]]
     if (length(in_scope) == 0L) next
     has_data <- present$year[
-      present$recipe_id == rid & present$component_code == comps$component_code[i]
+      present$recipe_id == rid & present$component_code == this_code
     ]
     gap_years <- setdiff(in_scope, has_data)
-    if (any(gap_years %in% covered_years)) return(TRUE)
+    if (length(gap_years) == 0L) next
+    other_covered_years <- covered$year[
+      covered$recipe_id == rid & covered$component_code != this_code
+    ]
+    if (any(gap_years %in% other_covered_years)) return(TRUE)
   }
   FALSE
 }

tests/testthat/test-recipes.R

@@ -203,6 +203,25 @@ test_that("signposting suggests corrections_combined across the 2011->2012 gap",
   expect_equal(hit$available_years, c(1967L, 2023L))
 })
 
+test_that("per-code gap does NOT fire when a code's only coverage is its own aggregate row (self-coverage is not \"other components\")", {
+  skip_if_no_corpus()
+  # Broward, FY2011 ONLY (isolating the 2011 half of the query above): E05,
+  # F05, and G05 each report SOLELY as a wide-era AGGREGATE row that year
+  # (216088, 1453, 270 respectively); E04/F04/G04 -- their modern-only
+  # siblings -- don't exist as codes at all before 2012, corpus-wide (zero
+  # rows for any government). Each component's own aggregate row would
+  # trivially satisfy a same-component "covered" check, but review-doc
+  # § 0.3's criterion is explicit that a gap must be covered by "OTHER
+  # components", not the gapped component's own aggregate form. With no
+  # OTHER component present for any of the three Corrections recipes in
+  # 2011, none of them should fire -- this is what the combined
+  # 2011-2012 test above actually relies on 2012 (E05 gapped, E04 -- a
+  # genuinely different component -- covers) to fire, not 2011.
+  r <- cog_spending("121011212191", years = 2011L, category = "Corrections")
+  prov <- attr(r, "provenance")
+  expect_length(prov$suggestions, 0L)
+})
+
 test_that("per-code gap fires even when a sibling code masks the whole-result check (Cleburne County, FY2012)", {
   skip_if_no_corpus()
   # Cleburne County, AL (canonical_govid 011029122489), FY2012: E04 ($854)