Chez Phase 2 (inc O): host String methods (jolt-nfca)

Port the java.lang.String/CharSequence method surface to the Chez RT so
(.toUpperCase s), (.substring s a b), (.indexOf s x), the regex methods
(.matches/.replaceAll/.replaceFirst/.split), etc. run on a string target.

natives-str.ss holds jolt-string-method, ported from the seed's surface in
eval_resolve.janet: ASCII case mapping (byte-oriented like the seed), -1 on
indexOf miss, flonum numeric returns to match jolt's number model, Scheme
chars for charAt, and the regex methods over the irregex compiled via
jolt-re-pattern. record-method-dispatch gains a string? arm that falls
through to it (unsupported methods still throw).

Corpus prelude floor 2002 -> 2026 (+24), 0 new divergences. _str 27/27 vs
build/jolt; full jpm test + conformance x3 green.

The (. x m) dot-form (the . special form, distinct from .method sugar) and
the clojure.string namespace (needs prelude plumbing + Pattern) stay deferred.

test/chez/_str.janet

@@ -0,0 +1,65 @@
+# jolt-nfca — host java.lang.String method interop on Chez: (.toUpperCase s),
+# (.indexOf s x), (.substring s a b), the regex methods (.matches/.replaceAll/
+# .replaceFirst), etc. Ported from the seed's string-methods surface
+# (src/jolt/eval_resolve.janet). Expectations are the build/jolt (seed) oracle.
+# An expected of :throws asserts a non-zero exit (unsupported method).
+#
+#   janet test/chez/_str.janet
+(def jolt-bin (or (os/getenv "JOLT_BIN") "bin/jolt-chez"))
+
+(def cases
+  [["toLowerCase"      "(.toLowerCase \"HI\")"                  "hi"]
+   ["toUpperCase"      "(.toUpperCase \"hi\")"                  "HI"]
+   ["trim"             "(.trim \"  x  \")"                      "x"]
+   ["length"           "(.length \"abc\")"                      "3"]
+   ["isEmpty"          "[(.isEmpty \"\") (.isEmpty \"a\")]"     "[true false]"]
+   ["indexOf hit"      "(.indexOf \"abc\" \"b\")"               "1"]
+   ["indexOf miss"     "(.indexOf \"abc\" \"z\")"               "-1"]
+   ["indexOf from"     "(.indexOf \"abab\" \"a\" 1)"            "2"]
+   ["indexOf int code" "(.indexOf \"a=b\" 61)"                  "1"]
+   ["lastIndexOf"      "(.lastIndexOf \"abab\" \"b\")"          "3"]
+   ["substring 1"      "(.substring \"abc\" 1)"                 "bc"]
+   ["substring 1 2"    "(.substring \"abc\" 1 2)"               "b"]
+   ["startsWith"       "(.startsWith \"abc\" \"ab\")"           "true"]
+   ["endsWith"         "(.endsWith \"abc\" \"bc\")"             "true"]
+   ["contains"         "(.contains \"abc\" \"b\")"              "true"]
+   ["replace literal"  "(.replace \"abc\" \"b\" \"x\")"         "axc"]
+   ["replace all occ"  "(.replace \"aaa\" \"a\" \"b\")"         "bbb"]
+   ["charAt"           "(.charAt \"abc\" 1)"                    "\\b"]
+   ["equalsIgnoreCase" "(.equalsIgnoreCase \"AbC\" \"aBc\")"    "true"]
+   ["toString"         "(.toString \"hi\")"                     "hi"]
+   ["concat"           "(.concat \"ab\" \"cd\")"                "abcd"]
+   ["matches whole"    "(.matches \"abc\" \"a.c\")"             "true"]
+   ["matches partial"  "(.matches \"abcd\" \"a.c\")"            "false"]
+   ["replaceAll"       "(.replaceAll \"a_b_c\" \"_\" \"-\")"    "a-b-c"]
+   ["replaceFirst"     "(.replaceFirst \"a_b_c\" \"_\" \"-\")"  "a-b_c"]
+   ["split regex"      "(vec (.split \"a,b,c\" \",\"))"         "[a b c]"]
+   ["unsupported"      "(.frobnicate \"abc\")"                  :throws]])
+
+(defn run-capture [expr]
+  (def proc (os/spawn [jolt-bin "-e" expr] :p {:out :pipe :err :pipe}))
+  (def out (ev/read (proc :out) 0x100000))
+  (def err (ev/read (proc :err) 0x100000))
+  (def code (os/proc-wait proc))
+  (def lines (filter (fn [l] (not (empty? l)))
+                     (string/split "\n" (string/trim (if out (string out) "")))))
+  [code (if (empty? lines) "" (last lines)) (if err (string err) "")])
+
+(var pass 0)
+(def fails @[])
+(each [label expr expected] cases
+  (def [code got err] (run-capture expr))
+  (cond
+    (= expected :throws)
+      (if (not= code 0) (++ pass)
+        (array/push fails [label (string "want throw, got `" got "` (exit 0)")]))
+    (not= code 0) (array/push fails [label (string "exit " code "; err: " (string/trim err))])
+    (= got expected) (++ pass)
+    (array/push fails [label (string "want `" expected "`, got `" got "`")])))
+
+(printf "\n_str parity [%s]: %d/%d passed" jolt-bin pass (length cases))
+(when (> (length fails) 0)
+  (printf "%d FAIL(s):" (length fails))
+  (each [l m] fails (printf "  FAIL [%s] %s" l m)))
+(flush)
+(os/exit (if (empty? fails) 0 1))

test/chez/run-corpus-prelude.janet

@@ -195,8 +195,13 @@
 # with-in-str/line-seq) 2000.
 # jolt-fmm4 ((type x) — :type meta override, record ns-qualified class-name
 # symbol, total value->taxonomy keyword mapping) 2002.
+# jolt-nfca (host java.lang.String method interop — jolt-string-method, the
+# portable String/CharSequence surface record-method-dispatch falls through to on
+# a string target: case/trim/length/indexOf/substring/startsWith/contains/replace/
+# charAt/equalsIgnoreCase + the regex methods matches/replaceAll/replaceFirst/
+# split) 2026.
 # Strided runs scale down.
-(def base-floor (scan-number (or (os/getenv "JOLT_CHEZ_PRELUDE_FLOOR") "2002")))
+(def base-floor (scan-number (or (os/getenv "JOLT_CHEZ_PRELUDE_FLOOR") "2026")))
 (def floor (if (os/getenv "JOLT_CORPUS_LIMIT") 0 base-floor))
 (when (or (> (length diverged) 0) (< pass floor))
   (printf "REGRESSION: pass %d < floor %d or %d new divergence(s)" pass floor (length diverged)))