js-on-sx: regex literal lex+parse+transpile+runtime stub

Lexer: js-regex-context? disambiguates / based on prior token;
read-regex handles [...] classes and \ escapes. Emits
{:type "regex" :value {:pattern :flags}}.

Parser: new primary branch → (js-regex pat flags).

Transpile: (js-regex-new pat flags).

Runtime: js-regex? predicate, js-regex-new builds tagged dict with
source/flags/global/ignoreCase/multiline/sticky/unicode/dotAll/
hasIndices/lastIndex. js-regex-invoke-method dispatches .test/.exec/
.toString. js-invoke-method detects regex receivers. Stub engine
uses js-string-index-of; __js_regex_platform__ + override! let a
real engine plug in later.

Runner: repeatable --filter flags (OR'd).

308/310 unit (+30 regex tests), 148/148 slice unchanged.

lib/js/test.sh

@@ -745,6 +745,90 @@ cat > "$TMPFILE" << 'EPOCHS'
 (epoch 938)
 (eval "(js-eval \"`[${''}-${''}]`\")")
 
+;; ── Phase 11.regex: regex literal lexing ────────────────────────
+;; Simple regex at start of file
+(epoch 1000)
+(eval "(get (nth (js-tokenize \"/abc/\") 0) :type)")
+(epoch 1001)
+(eval "(get (get (nth (js-tokenize \"/abc/\") 0) :value) :pattern)")
+(epoch 1002)
+(eval "(get (get (nth (js-tokenize \"/abc/\") 0) :value) :flags)")
+;; With flags
+(epoch 1003)
+(eval "(get (get (nth (js-tokenize \"/a+/gi\") 0) :value) :flags)")
+;; Character class with embedded /
+(epoch 1004)
+(eval "(get (get (nth (js-tokenize \"/[/]/\") 0) :value) :pattern)")
+;; Escaped /
+(epoch 1005)
+(eval "(get (get (nth (js-tokenize \"/a\\\\/b/\") 0) :value) :pattern)")
+;; After `return` keyword → regex
+(epoch 1006)
+(eval "(get (nth (js-tokenize \"return /x/\") 1) :type)")
+;; After `=` op → regex
+(epoch 1007)
+(eval "(get (nth (js-tokenize \"x = /y/\") 2) :type)")
+;; After ident `x` → division (not regex)
+(epoch 1008)
+(eval "(get (nth (js-tokenize \"a/b\") 1) :type)")
+(epoch 1009)
+(eval "(get (nth (js-tokenize \"a/b\") 1) :value)")
+;; After `)` → division
+(epoch 1010)
+(eval "(get (nth (js-tokenize \"(a)/b\") 3) :type)")
+;; After number → division
+(epoch 1011)
+(eval "(get (nth (js-tokenize \"1/2\") 1) :type)")
+;; Regex /= must still be division-assignment in expr context
+(epoch 1012)
+(eval "(get (nth (js-tokenize \"x/=2\") 1) :type)")
+(epoch 1013)
+(eval "(get (nth (js-tokenize \"x/=2\") 1) :value)")
+;; Inside function body after statement separator
+(epoch 1014)
+(eval "(get (nth (js-tokenize \"; /abc/\") 1) :type)")
+;; After `throw`
+(epoch 1015)
+(eval "(get (nth (js-tokenize \"throw /x/\") 1) :type)")
+
+;; ── Phase 11.regex: parser ──────────────────────────────────────
+(epoch 1020)
+(eval "(first (js-parse-expr \"/abc/\"))")
+(epoch 1021)
+(eval "(nth (js-parse-expr \"/foo/gi\") 1)")
+(epoch 1022)
+(eval "(nth (js-parse-expr \"/foo/gi\") 2)")
+
+;; ── Phase 11.regex: transpile ───────────────────────────────────
+(epoch 1030)
+(eval "(first (js-transpile (js-parse-expr \"/abc/\")))")
+
+;; ── Phase 11.regex: runtime — regex object shape ───────────────
+(epoch 1040)
+(eval "(get (js-regex-new \"ab\" \"g\") :source)")
+(epoch 1041)
+(eval "(get (js-regex-new \"ab\" \"g\") :flags)")
+(epoch 1042)
+(eval "(get (js-regex-new \"ab\" \"g\") :global)")
+(epoch 1043)
+(eval "(js-regex? (js-regex-new \"ab\" \"\"))")
+
+;; .source / .flags / .global etc via property access
+(epoch 1050)
+(eval "(js-eval \"/abc/g.source\")")
+(epoch 1051)
+(eval "(js-eval \"/abc/gi.flags\")")
+(epoch 1052)
+(eval "(js-eval \"/abc/g.global\")")
+(epoch 1053)
+(eval "(js-eval \"/abc/i.ignoreCase\")")
+
+;; .test() via stub: substring-based
+(epoch 1060)
+(eval "(js-eval \"/foo/.test('hello foo')\")")
+(epoch 1061)
+(eval "(js-eval \"/zzz/.test('hello')\")")
+
 EPOCHS
 
 OUTPUT=$(timeout 180 "$SX_SERVER" < "$TMPFILE" 2>/dev/null)
@@ -1144,6 +1228,48 @@ check 936 'bare ${42}'               '"42"'
 check 937 "expr in interp"           '"len is 12"'
 check 938 "empty interps"            '"[-]"'
 
+# ── Phase 11.regex: lexer ────────────────────────────────────────
+check 1000 "regex at sof → type"           '"regex"'
+check 1001 "regex pattern"                  '"abc"'
+check 1002 "regex empty flags"              '""'
+check 1003 "regex with gi flags"            '"gi"'
+check 1004 "regex class with /"             '"[/]"'
+check 1005 "regex escaped /"                '"a\\/b"'
+check 1006 "after return → regex"           '"regex"'
+check 1007 "after = → regex"                '"regex"'
+check 1008 "after ident → op"               '"op"'
+check 1009 "after ident div value"          '"/"'
+check 1010 "after ) → op"                   '"op"'
+check 1011 "after number → op"              '"op"'
+check 1012 "x/=2 is /=-assign"              '"op"'
+check 1013 "x/=2 /= op value"               '"/="'
+check 1014 "after ; → regex"                '"regex"'
+check 1015 "after throw → regex"            '"regex"'
+
+# ── Phase 11.regex: parser ───────────────────────────────────────
+check 1020 "parse /abc/ head"               'js-regex'
+check 1021 "parse pattern arg"              '"foo"'
+check 1022 "parse flags arg"                '"gi"'
+
+# ── Phase 11.regex: transpile ────────────────────────────────────
+check 1030 "transpile uses js-regex-new"    'js-regex-new'
+
+# ── Phase 11.regex: runtime obj ──────────────────────────────────
+check 1040 "regex source"                   '"ab"'
+check 1041 "regex flags"                    '"g"'
+check 1042 "regex global true"              'true'
+check 1043 "js-regex? true"                 'true'
+
+# ── Phase 11.regex: property access ──────────────────────────────
+check 1050 "literal .source"                '"abc"'
+check 1051 "literal .flags"                 '"gi"'
+check 1052 "literal .global"                'true'
+check 1053 "literal .ignoreCase"            'true'
+
+# ── Phase 11.regex: test() ───────────────────────────────────────
+check 1060 "test match"                     'true'
+check 1061 "test no match"                  'false'
+
 TOTAL=$((PASS + FAIL))
 if [ $FAIL -eq 0 ]; then
   echo "✓ $PASS/$TOTAL JS-on-SX tests passed"