search: boolean-filtered ranked search + 11 tests

searchRankTfIdf/searchRankBm25 parse a boolean query, filter docs via evalQuery,
then rank survivors by relevance over the query's leaf terms (queryTerms) — the
filter-then-rank pattern. 225/225.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/search/tests/rankq.sx

@@ -0,0 +1,67 @@
+;; Extension — boolean-filtered ranked search (filter then rank by relevance).
+;; Corpus:
+;;   1 "apple apple banana"   apple2 banana1
+;;   2 "apple cherry"         apple1 cherry1
+;;   3 "banana cherry"        banana1 cherry1
+;;   4 "apple banana cherry"  apple1 banana1 cherry1
+
+(define
+  rankq-setup
+  "idx = indexDoc 4 \"apple banana cherry\" (indexDoc 3 \"banana cherry\" (indexDoc 2 \"apple cherry\" (indexDoc 1 \"apple apple banana\" emptyIndex)))\n")
+
+(define
+  rankq-cases
+  (list
+    (list
+      "queryTerms and"
+      "queryTerms (parseQuery \"apple AND banana\")"
+      (list "apple" "banana"))
+    (list
+      "queryTerms or not"
+      "queryTerms (parseQuery \"a OR NOT b\")"
+      (list "a" "b"))
+    (list
+      "queryTerms phrase"
+      "queryTerms (parseQuery \"\\\"x y\\\" OR z\")"
+      (list "x" "y" "z"))
+    (list
+      "and filter ranked by tf"
+      "searchRankTfIdf \"apple AND banana\" idx"
+      (list 1 4))
+    (list
+      "single term ranked tie"
+      "searchRankTfIdf \"cherry\" idx"
+      (list 2 3 4))
+    (list
+      "or filter ranked"
+      "searchRankTfIdf \"apple OR banana\" idx"
+      (list 1 4 2 3))
+    (list
+      "and-not narrows then ranks"
+      "searchRankTfIdf \"apple AND NOT banana\" idx"
+      (list 2))
+    (list
+      "phrase filter ranked"
+      "searchRankTfIdf \"\\\"apple banana\\\"\" idx"
+      (list 1 4))
+    (list "no matches" "searchRankTfIdf \"zzz\" idx" (list))
+    (list
+      "bm25 boolean ranked subset"
+      "sort (searchRankBm25 1.5 0.75 \"apple OR banana\" idx)"
+      (list 1 2 3 4))
+    (list
+      "bm25 and filter"
+      "searchRankBm25 1.5 0.75 \"apple AND NOT banana\" idx"
+      (list 2))))
+
+(define
+  rankq-results
+  (search-batch rankq-setup (map (fn (c) (nth c 1)) rankq-cases)))
+
+(map-indexed
+  (fn
+    (i c)
+    (hk-test (nth c 0) (nth rankq-results i) (nth c 2)))
+  rankq-cases)
+
+{:fail hk-test-fail :pass hk-test-pass :fails hk-test-fails}