js: let/const TDZ infrastructure — sentinel + kind threading in transpiler

Threads declaration kind ("var"/"let"/"const") through js-transpile-var →
js-vardecl-forms so the transpiler knows which kind is being declared.
Infrastructure for full TDZ enforcement: js-tdz-check can wrap let/const
reads to raise TypeError before initialization.

Updates plans/js-on-sx.md: ticks [x] for TDZ, marks regex blocker RESOLVED,
adds progress log entry for 2026-04-25.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/js/conformance.sh

@@ -49,6 +49,8 @@ trap "rm -f $TMPFILE" EXIT
   echo '(load "lib/js/transpile.sx")'
   echo '(epoch 5)'
   echo '(load "lib/js/runtime.sx")'
+  echo '(epoch 6)'
+  echo '(load "lib/js/regex.sx")'
 
   epoch=100
   for f in "${FIXTURES[@]}"; do

lib/js/regex.sx

@@ -0,0 +1,943 @@
+;; lib/js/regex.sx — pure-SX recursive backtracking regex engine
+;;
+;; Installed via (js-regex-platform-override! ...) at load time.
+;; Covers: character classes (\d\w\s . [abc] [^abc] [a-z]),
+;;   anchors (^ $ \b \B), quantifiers (* + ? {n,m} lazy variants),
+;;   groups (capturing + non-capturing), alternation (a|b),
+;;   flags: i (case-insensitive), g (global), m (multiline).
+;;
+;; Architecture:
+;;   1. rx-parse-pattern  — pattern string → compiled node list
+;;   2. rx-match-nodes    — recursive backtracker
+;;   3. rx-exec / rx-test — public interface
+;;   4. Install as {:test rx-test :exec rx-exec}
+
+;; ── Utilities ─────────────────────────────────────────────────────
+
+(define
+  rx-char-at
+  (fn (s i) (if (and (>= i 0) (< i (len s))) (char-at s i) "")))
+
+(define
+  rx-digit?
+  (fn
+    (c)
+    (and (not (= c "")) (>= (char-code c) 48) (<= (char-code c) 57))))
+
+(define
+  rx-word?
+  (fn
+    (c)
+    (and
+      (not (= c ""))
+      (or
+        (and (>= (char-code c) 65) (<= (char-code c) 90))
+        (and (>= (char-code c) 97) (<= (char-code c) 122))
+        (and (>= (char-code c) 48) (<= (char-code c) 57))
+        (= c "_")))))
+
+(define
+  rx-space?
+  (fn
+    (c)
+    (or (= c " ") (= c "\t") (= c "\n") (= c "\r") (= c "\\f") (= c ""))))
+
+(define rx-newline? (fn (c) (or (= c "\n") (= c "\r"))))
+
+(define
+  rx-downcase-char
+  (fn
+    (c)
+    (let
+      ((cc (char-code c)))
+      (if (and (>= cc 65) (<= cc 90)) (char-from-code (+ cc 32)) c))))
+
+(define
+  rx-char-eq?
+  (fn
+    (a b ci?)
+    (if ci? (= (rx-downcase-char a) (rx-downcase-char b)) (= a b))))
+
+(define
+  rx-parse-int
+  (fn
+    (pat i acc)
+    (let
+      ((c (rx-char-at pat i)))
+      (if
+        (rx-digit? c)
+        (rx-parse-int pat (+ i 1) (+ (* acc 10) (- (char-code c) 48)))
+        (list acc i)))))
+
+(define
+  rx-hex-digit-val
+  (fn
+    (c)
+    (cond
+      ((and (>= (char-code c) 48) (<= (char-code c) 57))
+        (- (char-code c) 48))
+      ((and (>= (char-code c) 65) (<= (char-code c) 70))
+        (+ 10 (- (char-code c) 65)))
+      ((and (>= (char-code c) 97) (<= (char-code c) 102))
+        (+ 10 (- (char-code c) 97)))
+      (else -1))))
+
+(define
+  rx-parse-hex-n
+  (fn
+    (pat i n acc)
+    (if
+      (= n 0)
+      (list (char-from-code acc) i)
+      (let
+        ((v (rx-hex-digit-val (rx-char-at pat i))))
+        (if
+          (< v 0)
+          (list (char-from-code acc) i)
+          (rx-parse-hex-n pat (+ i 1) (- n 1) (+ (* acc 16) v)))))))
+
+;; ── Pattern compiler ──────────────────────────────────────────────
+
+;; Node types (stored in dicts with "__t__" key):
+;;   literal  : {:__t__ "literal" :__c__ char}
+;;   any      : {:__t__ "any"}
+;;   class-d  : {:__t__ "class-d"  :__neg__ bool}
+;;   class-w  : {:__t__ "class-w"  :__neg__ bool}
+;;   class-s  : {:__t__ "class-s"  :__neg__ bool}
+;;   char-class: {:__t__ "char-class" :__neg__ bool :__items__ list}
+;;   anchor-start / anchor-end / anchor-word / anchor-nonword
+;;   quant    : {:__t__ "quant" :__node__ n :__min__ m :__max__ mx :__lazy__ bool}
+;;   group    : {:__t__ "group" :__idx__ i :__nodes__ list}
+;;   ncgroup  : {:__t__ "ncgroup" :__nodes__ list}
+;;   alt      : {:__t__ "alt" :__branches__ list-of-node-lists}
+
+;; parse one escape after `\`, returns (node new-i)
+(define
+  rx-parse-escape
+  (fn
+    (pat i)
+    (let
+      ((c (rx-char-at pat i)))
+      (cond
+        ((= c "d") (list (dict "__t__" "class-d" "__neg__" false) (+ i 1)))
+        ((= c "D") (list (dict "__t__" "class-d" "__neg__" true) (+ i 1)))
+        ((= c "w") (list (dict "__t__" "class-w" "__neg__" false) (+ i 1)))
+        ((= c "W") (list (dict "__t__" "class-w" "__neg__" true) (+ i 1)))
+        ((= c "s") (list (dict "__t__" "class-s" "__neg__" false) (+ i 1)))
+        ((= c "S") (list (dict "__t__" "class-s" "__neg__" true) (+ i 1)))
+        ((= c "b") (list (dict "__t__" "anchor-word") (+ i 1)))
+        ((= c "B") (list (dict "__t__" "anchor-nonword") (+ i 1)))
+        ((= c "n") (list (dict "__t__" "literal" "__c__" "\n") (+ i 1)))
+        ((= c "r") (list (dict "__t__" "literal" "__c__" "\r") (+ i 1)))
+        ((= c "t") (list (dict "__t__" "literal" "__c__" "\t") (+ i 1)))
+        ((= c "f") (list (dict "__t__" "literal" "__c__" "\\f") (+ i 1)))
+        ((= c "v") (list (dict "__t__" "literal" "__c__" "") (+ i 1)))
+        ((= c "u")
+          (let
+            ((res (rx-parse-hex-n pat (+ i 1) 4 0)))
+            (list (dict "__t__" "literal" "__c__" (nth res 0)) (nth res 1))))
+        ((= c "x")
+          (let
+            ((res (rx-parse-hex-n pat (+ i 1) 2 0)))
+            (list (dict "__t__" "literal" "__c__" (nth res 0)) (nth res 1))))
+        (else (list (dict "__t__" "literal" "__c__" c) (+ i 1)))))))
+
+;; parse a char-class item inside [...], returns (item new-i)
+(define
+  rx-parse-class-item
+  (fn
+    (pat i)
+    (let
+      ((c (rx-char-at pat i)))
+      (cond
+        ((= c "\\")
+          (let
+            ((esc (rx-parse-escape pat (+ i 1))))
+            (let
+              ((node (nth esc 0)) (ni (nth esc 1)))
+              (let
+                ((t (get node "__t__")))
+                (cond
+                  ((= t "class-d")
+                    (list
+                      (dict "kind" "class-d" "neg" (get node "__neg__"))
+                      ni))
+                  ((= t "class-w")
+                    (list
+                      (dict "kind" "class-w" "neg" (get node "__neg__"))
+                      ni))
+                  ((= t "class-s")
+                    (list
+                      (dict "kind" "class-s" "neg" (get node "__neg__"))
+                      ni))
+                  (else
+                    (let
+                      ((lc (get node "__c__")))
+                      (if
+                        (and
+                          (= (rx-char-at pat ni) "-")
+                          (not (= (rx-char-at pat (+ ni 1)) "]")))
+                        (let
+                          ((hi-c (rx-char-at pat (+ ni 1))))
+                          (list
+                            (dict "kind" "range" "lo" lc "hi" hi-c)
+                            (+ ni 2)))
+                        (list (dict "kind" "lit" "c" lc) ni)))))))))
+        (else
+          (if
+            (and
+              (not (= c ""))
+              (= (rx-char-at pat (+ i 1)) "-")
+              (not (= (rx-char-at pat (+ i 2)) "]"))
+              (not (= (rx-char-at pat (+ i 2)) "")))
+            (let
+              ((hi-c (rx-char-at pat (+ i 2))))
+              (list (dict "kind" "range" "lo" c "hi" hi-c) (+ i 3)))
+            (list (dict "kind" "lit" "c" c) (+ i 1))))))))
+
+(define
+  rx-parse-class-items
+  (fn
+    (pat i items)
+    (let
+      ((c (rx-char-at pat i)))
+      (if
+        (or (= c "]") (= c ""))
+        (list items i)
+        (let
+          ((res (rx-parse-class-item pat i)))
+          (begin
+            (append! items (nth res 0))
+            (rx-parse-class-items pat (nth res 1) items)))))))
+
+;; parse a sequence until stop-ch or EOF; returns (nodes new-i groups-count)
+(define
+  rx-parse-seq
+  (fn
+    (pat i stop-ch ds)
+    (let
+      ((c (rx-char-at pat i)))
+      (cond
+        ((= c "") (list (get ds "nodes") i (get ds "groups")))
+        ((= c stop-ch) (list (get ds "nodes") i (get ds "groups")))
+        ((= c "|") (rx-parse-alt-rest pat i ds))
+        (else
+          (let
+            ((res (rx-parse-atom pat i ds)))
+            (let
+              ((node (nth res 0)) (ni (nth res 1)) (ds2 (nth res 2)))
+              (let
+                ((qres (rx-parse-quant pat ni node)))
+                (begin
+                  (append! (get ds2 "nodes") (nth qres 0))
+                  (rx-parse-seq pat (nth qres 1) stop-ch ds2))))))))))
+
+;; when we hit | inside a sequence, collect all alternatives
+(define
+  rx-parse-alt-rest
+  (fn
+    (pat i ds)
+    (let
+      ((left-branch (get ds "nodes")) (branches (list)))
+      (begin
+        (append! branches left-branch)
+        (rx-parse-alt-branches pat i (get ds "groups") branches)))))
+
+(define
+  rx-parse-alt-branches
+  (fn
+    (pat i n-groups branches)
+    (let
+      ((new-nodes (list)) (ds2 (dict "groups" n-groups "nodes" new-nodes)))
+      (let
+        ((res (rx-parse-seq pat (+ i 1) "|" ds2)))
+        (begin
+          (append! branches (nth res 0))
+          (let
+            ((ni2 (nth res 1)) (g2 (nth res 2)))
+            (if
+              (= (rx-char-at pat ni2) "|")
+              (rx-parse-alt-branches pat ni2 g2 branches)
+              (list
+                (list (dict "__t__" "alt" "__branches__" branches))
+                ni2
+                g2))))))))
+
+;; parse quantifier suffix, returns (node new-i)
+(define
+  rx-parse-quant
+  (fn
+    (pat i node)
+    (let
+      ((c (rx-char-at pat i)))
+      (cond
+        ((= c "*")
+          (let
+            ((lazy? (= (rx-char-at pat (+ i 1)) "?")))
+            (list
+              (dict
+                "__t__"
+                "quant"
+                "__node__"
+                node
+                "__min__"
+                0
+                "__max__"
+                -1
+                "__lazy__"
+                lazy?)
+              (if lazy? (+ i 2) (+ i 1)))))
+        ((= c "+")
+          (let
+            ((lazy? (= (rx-char-at pat (+ i 1)) "?")))
+            (list
+              (dict
+                "__t__"
+                "quant"
+                "__node__"
+                node
+                "__min__"
+                1
+                "__max__"
+                -1
+                "__lazy__"
+                lazy?)
+              (if lazy? (+ i 2) (+ i 1)))))
+        ((= c "?")
+          (let
+            ((lazy? (= (rx-char-at pat (+ i 1)) "?")))
+            (list
+              (dict
+                "__t__"
+                "quant"
+                "__node__"
+                node
+                "__min__"
+                0
+                "__max__"
+                1
+                "__lazy__"
+                lazy?)
+              (if lazy? (+ i 2) (+ i 1)))))
+        ((= c "{")
+          (let
+            ((mres (rx-parse-int pat (+ i 1) 0)))
+            (let
+              ((mn (nth mres 0)) (mi (nth mres 1)))
+              (let
+                ((sep (rx-char-at pat mi)))
+                (cond
+                  ((= sep "}")
+                    (let
+                      ((lazy? (= (rx-char-at pat (+ mi 1)) "?")))
+                      (list
+                        (dict
+                          "__t__"
+                          "quant"
+                          "__node__"
+                          node
+                          "__min__"
+                          mn
+                          "__max__"
+                          mn
+                          "__lazy__"
+                          lazy?)
+                        (if lazy? (+ mi 2) (+ mi 1)))))
+                  ((= sep ",")
+                    (let
+                      ((c2 (rx-char-at pat (+ mi 1))))
+                      (if
+                        (= c2 "}")
+                        (let
+                          ((lazy? (= (rx-char-at pat (+ mi 2)) "?")))
+                          (list
+                            (dict
+                              "__t__"
+                              "quant"
+                              "__node__"
+                              node
+                              "__min__"
+                              mn
+                              "__max__"
+                              -1
+                              "__lazy__"
+                              lazy?)
+                            (if lazy? (+ mi 3) (+ mi 2))))
+                        (let
+                          ((mxres (rx-parse-int pat (+ mi 1) 0)))
+                          (let
+                            ((mx (nth mxres 0)) (mxi (nth mxres 1)))
+                            (let
+                              ((lazy? (= (rx-char-at pat (+ mxi 1)) "?")))
+                              (list
+                                (dict
+                                  "__t__"
+                                  "quant"
+                                  "__node__"
+                                  node
+                                  "__min__"
+                                  mn
+                                  "__max__"
+                                  mx
+                                  "__lazy__"
+                                  lazy?)
+                                (if lazy? (+ mxi 2) (+ mxi 1)))))))))
+                  (else (list node i)))))))
+        (else (list node i))))))
+
+;; parse one atom, returns (node new-i new-ds)
+(define
+  rx-parse-atom
+  (fn
+    (pat i ds)
+    (let
+      ((c (rx-char-at pat i)))
+      (cond
+        ((= c ".") (list (dict "__t__" "any") (+ i 1) ds))
+        ((= c "^") (list (dict "__t__" "anchor-start") (+ i 1) ds))
+        ((= c "$") (list (dict "__t__" "anchor-end") (+ i 1) ds))
+        ((= c "\\")
+          (let
+            ((esc (rx-parse-escape pat (+ i 1))))
+            (list (nth esc 0) (nth esc 1) ds)))
+        ((= c "[")
+          (let
+            ((neg? (= (rx-char-at pat (+ i 1)) "^")))
+            (let
+              ((start (if neg? (+ i 2) (+ i 1))) (items (list)))
+              (let
+                ((res (rx-parse-class-items pat start items)))
+                (let
+                  ((ci (nth res 1)))
+                  (list
+                    (dict
+                      "__t__"
+                      "char-class"
+                      "__neg__"
+                      neg?
+                      "__items__"
+                      items)
+                    (+ ci 1)
+                    ds))))))
+        ((= c "(")
+          (let
+            ((c2 (rx-char-at pat (+ i 1))))
+            (if
+              (and (= c2 "?") (= (rx-char-at pat (+ i 2)) ":"))
+              (let
+                ((inner-nodes (list))
+                  (inner-ds
+                    (dict "groups" (get ds "groups") "nodes" inner-nodes)))
+                (let
+                  ((res (rx-parse-seq pat (+ i 3) ")" inner-ds)))
+                  (list
+                    (dict "__t__" "ncgroup" "__nodes__" (nth res 0))
+                    (+ (nth res 1) 1)
+                    (dict "groups" (nth res 2) "nodes" (get ds "nodes")))))
+              (let
+                ((gidx (+ (get ds "groups") 1)) (inner-nodes (list)))
+                (let
+                  ((inner-ds (dict "groups" gidx "nodes" inner-nodes)))
+                  (let
+                    ((res (rx-parse-seq pat (+ i 1) ")" inner-ds)))
+                    (list
+                      (dict
+                        "__t__"
+                        "group"
+                        "__idx__"
+                        gidx
+                        "__nodes__"
+                        (nth res 0))
+                      (+ (nth res 1) 1)
+                      (dict "groups" (nth res 2) "nodes" (get ds "nodes")))))))))
+        (else (list (dict "__t__" "literal" "__c__" c) (+ i 1) ds))))))
+
+;; top-level compile
+(define
+  rx-compile
+  (fn
+    (pattern)
+    (let
+      ((nodes (list)) (ds (dict "groups" 0 "nodes" nodes)))
+      (let
+        ((res (rx-parse-seq pattern 0 "" ds)))
+        (dict "nodes" (nth res 0) "ngroups" (nth res 2))))))
+
+;; ── Matcher ───────────────────────────────────────────────────────
+
+;; Match a char-class item against character c
+(define
+  rx-item-matches?
+  (fn
+    (item c ci?)
+    (let
+      ((kind (get item "kind")))
+      (cond
+        ((= kind "lit") (rx-char-eq? c (get item "c") ci?))
+        ((= kind "range")
+          (let
+            ((lo (if ci? (rx-downcase-char (get item "lo")) (get item "lo")))
+              (hi
+                (if ci? (rx-downcase-char (get item "hi")) (get item "hi")))
+              (dc (if ci? (rx-downcase-char c) c)))
+            (and
+              (>= (char-code dc) (char-code lo))
+              (<= (char-code dc) (char-code hi)))))
+        ((= kind "class-d")
+          (let ((m (rx-digit? c))) (if (get item "neg") (not m) m)))
+        ((= kind "class-w")
+          (let ((m (rx-word? c))) (if (get item "neg") (not m) m)))
+        ((= kind "class-s")
+          (let ((m (rx-space? c))) (if (get item "neg") (not m) m)))
+        (else false)))))
+
+(define
+  rx-class-items-any?
+  (fn
+    (items c ci?)
+    (if
+      (empty? items)
+      false
+      (if
+        (rx-item-matches? (first items) c ci?)
+        true
+        (rx-class-items-any? (rest items) c ci?)))))
+
+(define
+  rx-class-matches?
+  (fn
+    (node c ci?)
+    (let
+      ((neg? (get node "__neg__")) (items (get node "__items__")))
+      (let
+        ((hit (rx-class-items-any? items c ci?)))
+        (if neg? (not hit) hit)))))
+
+;; Word boundary check
+(define
+  rx-is-word-boundary?
+  (fn
+    (s i slen)
+    (let
+      ((before (if (> i 0) (rx-word? (char-at s (- i 1))) false))
+        (after (if (< i slen) (rx-word? (char-at s i)) false)))
+      (not (= before after)))))
+
+;; ── Core matcher ──────────────────────────────────────────────────
+;;
+;; rx-match-nodes : nodes s i slen ci? mi? groups → end-pos or -1
+;;
+;; Matches `nodes` starting at position `i` in string `s`.
+;; Returns the position after the last character consumed, or -1 on failure.
+;; Mutates `groups` dict to record captures.
+
+(define
+  rx-match-nodes
+  (fn
+    (nodes s i slen ci? mi? groups)
+    (if
+      (empty? nodes)
+      i
+      (let
+        ((node (first nodes)) (rest-nodes (rest nodes)))
+        (let
+          ((t (get node "__t__")))
+          (cond
+            ((= t "literal")
+              (if
+                (and
+                  (< i slen)
+                  (rx-char-eq? (char-at s i) (get node "__c__") ci?))
+                (rx-match-nodes rest-nodes s (+ i 1) slen ci? mi? groups)
+                -1))
+            ((= t "any")
+              (if
+                (and (< i slen) (not (rx-newline? (char-at s i))))
+                (rx-match-nodes rest-nodes s (+ i 1) slen ci? mi? groups)
+                -1))
+            ((= t "class-d")
+              (let
+                ((m (and (< i slen) (rx-digit? (char-at s i)))))
+                (if
+                  (if (get node "__neg__") (not m) m)
+                  (rx-match-nodes rest-nodes s (+ i 1) slen ci? mi? groups)
+                  -1)))
+            ((= t "class-w")
+              (let
+                ((m (and (< i slen) (rx-word? (char-at s i)))))
+                (if
+                  (if (get node "__neg__") (not m) m)
+                  (rx-match-nodes rest-nodes s (+ i 1) slen ci? mi? groups)
+                  -1)))
+            ((= t "class-s")
+              (let
+                ((m (and (< i slen) (rx-space? (char-at s i)))))
+                (if
+                  (if (get node "__neg__") (not m) m)
+                  (rx-match-nodes rest-nodes s (+ i 1) slen ci? mi? groups)
+                  -1)))
+            ((= t "char-class")
+              (if
+                (and (< i slen) (rx-class-matches? node (char-at s i) ci?))
+                (rx-match-nodes rest-nodes s (+ i 1) slen ci? mi? groups)
+                -1))
+            ((= t "anchor-start")
+              (if
+                (or
+                  (= i 0)
+                  (and mi? (rx-newline? (rx-char-at s (- i 1)))))
+                (rx-match-nodes rest-nodes s i slen ci? mi? groups)
+                -1))
+            ((= t "anchor-end")
+              (if
+                (or (= i slen) (and mi? (rx-newline? (rx-char-at s i))))
+                (rx-match-nodes rest-nodes s i slen ci? mi? groups)
+                -1))
+            ((= t "anchor-word")
+              (if
+                (rx-is-word-boundary? s i slen)
+                (rx-match-nodes rest-nodes s i slen ci? mi? groups)
+                -1))
+            ((= t "anchor-nonword")
+              (if
+                (not (rx-is-word-boundary? s i slen))
+                (rx-match-nodes rest-nodes s i slen ci? mi? groups)
+                -1))
+            ((= t "group")
+              (let
+                ((gidx (get node "__idx__"))
+                  (inner (get node "__nodes__")))
+                (let
+                  ((g-end (rx-match-nodes inner s i slen ci? mi? groups)))
+                  (if
+                    (>= g-end 0)
+                    (begin
+                      (dict-set!
+                        groups
+                        (js-to-string gidx)
+                        (substring s i g-end))
+                      (let
+                        ((final-end (rx-match-nodes rest-nodes s g-end slen ci? mi? groups)))
+                        (if
+                          (>= final-end 0)
+                          final-end
+                          (begin
+                            (dict-set! groups (js-to-string gidx) nil)
+                            -1))))
+                    -1))))
+            ((= t "ncgroup")
+              (let
+                ((inner (get node "__nodes__")))
+                (rx-match-nodes
+                  (append inner rest-nodes)
+                  s
+                  i
+                  slen
+                  ci?
+                  mi?
+                  groups)))
+            ((= t "alt")
+              (let
+                ((branches (get node "__branches__")))
+                (rx-try-branches branches rest-nodes s i slen ci? mi? groups)))
+            ((= t "quant")
+              (let
+                ((inner-node (get node "__node__"))
+                  (mn (get node "__min__"))
+                  (mx (get node "__max__"))
+                  (lazy? (get node "__lazy__")))
+                (if
+                  lazy?
+                  (rx-quant-lazy
+                    inner-node
+                    mn
+                    mx
+                    rest-nodes
+                    s
+                    i
+                    slen
+                    ci?
+                    mi?
+                    groups
+                    0)
+                  (rx-quant-greedy
+                    inner-node
+                    mn
+                    mx
+                    rest-nodes
+                    s
+                    i
+                    slen
+                    ci?
+                    mi?
+                    groups
+                    0))))
+            (else -1)))))))
+
+(define
+  rx-try-branches
+  (fn
+    (branches rest-nodes s i slen ci? mi? groups)
+    (if
+      (empty? branches)
+      -1
+      (let
+        ((res (rx-match-nodes (append (first branches) rest-nodes) s i slen ci? mi? groups)))
+        (if
+          (>= res 0)
+          res
+          (rx-try-branches (rest branches) rest-nodes s i slen ci? mi? groups))))))
+
+;; Greedy: expand as far as possible, then try rest from the longest match
+;; Strategy: recurse forward (extend first); only try rest when extension fails
+(define
+  rx-quant-greedy
+  (fn
+    (inner-node mn mx rest-nodes s i slen ci? mi? groups count)
+    (let
+      ((can-extend (and (< i slen) (or (= mx -1) (< count mx)))))
+      (if
+        can-extend
+        (let
+          ((ni (rx-match-one inner-node s i slen ci? mi? groups)))
+          (if
+            (>= ni 0)
+            (let
+              ((res (rx-quant-greedy inner-node mn mx rest-nodes s ni slen ci? mi? groups (+ count 1))))
+              (if
+                (>= res 0)
+                res
+                (if
+                  (>= count mn)
+                  (rx-match-nodes rest-nodes s i slen ci? mi? groups)
+                  -1)))
+            (if
+              (>= count mn)
+              (rx-match-nodes rest-nodes s i slen ci? mi? groups)
+              -1)))
+        (if
+          (>= count mn)
+          (rx-match-nodes rest-nodes s i slen ci? mi? groups)
+          -1)))))
+
+;; Lazy: try rest first, extend only if rest fails
+(define
+  rx-quant-lazy
+  (fn
+    (inner-node mn mx rest-nodes s i slen ci? mi? groups count)
+    (if
+      (>= count mn)
+      (let
+        ((res (rx-match-nodes rest-nodes s i slen ci? mi? groups)))
+        (if
+          (>= res 0)
+          res
+          (if
+            (and (< i slen) (or (= mx -1) (< count mx)))
+            (let
+              ((ni (rx-match-one inner-node s i slen ci? mi? groups)))
+              (if
+                (>= ni 0)
+                (rx-quant-lazy
+                  inner-node
+                  mn
+                  mx
+                  rest-nodes
+                  s
+                  ni
+                  slen
+                  ci?
+                  mi?
+                  groups
+                  (+ count 1))
+                -1))
+            -1)))
+      (if
+        (< i slen)
+        (let
+          ((ni (rx-match-one inner-node s i slen ci? mi? groups)))
+          (if
+            (>= ni 0)
+            (rx-quant-lazy
+              inner-node
+              mn
+              mx
+              rest-nodes
+              s
+              ni
+              slen
+              ci?
+              mi?
+              groups
+              (+ count 1))
+            -1))
+        -1))))
+
+;; Match a single node at position i, return new pos or -1
+(define
+  rx-match-one
+  (fn
+    (node s i slen ci? mi? groups)
+    (rx-match-nodes (list node) s i slen ci? mi? groups)))
+
+;; ── Engine entry points ───────────────────────────────────────────
+
+;; Try matching at exactly position i. Returns result dict or nil.
+(define
+  rx-try-at
+  (fn
+    (compiled s i slen ci? mi?)
+    (let
+      ((nodes (get compiled "nodes")) (ngroups (get compiled "ngroups")))
+      (let
+        ((groups (dict)))
+        (let
+          ((end (rx-match-nodes nodes s i slen ci? mi? groups)))
+          (if
+            (>= end 0)
+            (dict "start" i "end" end "groups" groups "ngroups" ngroups)
+            nil))))))
+
+;; Find first match scanning from search-start.
+(define
+  rx-find-from
+  (fn
+    (compiled s search-start slen ci? mi?)
+    (if
+      (> search-start slen)
+      nil
+      (let
+        ((res (rx-try-at compiled s search-start slen ci? mi?)))
+        (if
+          res
+          res
+          (rx-find-from compiled s (+ search-start 1) slen ci? mi?))))))
+
+;; Build exec result dict from raw match result
+(define
+  rx-build-exec-result
+  (fn
+    (s match-res)
+    (let
+      ((start (get match-res "start"))
+        (end (get match-res "end"))
+        (groups (get match-res "groups"))
+        (ngroups (get match-res "ngroups")))
+      (let
+        ((matched (substring s start end))
+          (caps (rx-build-captures groups ngroups 1)))
+        (dict "match" matched "index" start "input" s "groups" caps)))))
+
+(define
+  rx-build-captures
+  (fn
+    (groups ngroups idx)
+    (if
+      (> idx ngroups)
+      (list)
+      (let
+        ((cap (get groups (js-to-string idx))))
+        (cons
+          (if (= cap nil) :js-undefined cap)
+          (rx-build-captures groups ngroups (+ idx 1)))))))
+
+;; ── Public interface ──────────────────────────────────────────────
+
+;; Lazy compile: build NFA on first use, cache under "__compiled__"
+(define
+  rx-ensure-compiled!
+  (fn
+    (rx)
+    (if
+      (dict-has? rx "__compiled__")
+      (get rx "__compiled__")
+      (let
+        ((c (rx-compile (get rx "source"))))
+        (begin (dict-set! rx "__compiled__" c) c)))))
+
+(define
+  rx-test
+  (fn
+    (rx s)
+    (let
+      ((compiled (rx-ensure-compiled! rx))
+        (ci? (get rx "ignoreCase"))
+        (mi? (get rx "multiline"))
+        (slen (len s)))
+      (let
+        ((start (if (get rx "global") (let ((li (get rx "lastIndex"))) (if (number? li) li 0)) 0)))
+        (let
+          ((res (rx-find-from compiled s start slen ci? mi?)))
+          (if
+            (get rx "global")
+            (begin
+              (dict-set! rx "lastIndex" (if res (get res "end") 0))
+              (if res true false))
+            (if res true false)))))))
+
+(define
+  rx-exec
+  (fn
+    (rx s)
+    (let
+      ((compiled (rx-ensure-compiled! rx))
+        (ci? (get rx "ignoreCase"))
+        (mi? (get rx "multiline"))
+        (slen (len s)))
+      (let
+        ((start (if (get rx "global") (let ((li (get rx "lastIndex"))) (if (number? li) li 0)) 0)))
+        (let
+          ((res (rx-find-from compiled s start slen ci? mi?)))
+          (if
+            res
+            (begin
+              (when
+                (get rx "global")
+                (dict-set! rx "lastIndex" (get res "end")))
+              (rx-build-exec-result s res))
+            (begin
+              (when (get rx "global") (dict-set! rx "lastIndex" 0))
+              nil)))))))
+
+;; match-all for String.prototype.matchAll
+(define
+  js-regex-match-all
+  (fn
+    (rx s)
+    (let
+      ((compiled (rx-ensure-compiled! rx))
+        (ci? (get rx "ignoreCase"))
+        (mi? (get rx "multiline"))
+        (slen (len s))
+        (results (list)))
+      (rx-match-all-loop compiled s 0 slen ci? mi? results))))
+
+(define
+  rx-match-all-loop
+  (fn
+    (compiled s i slen ci? mi? results)
+    (if
+      (> i slen)
+      results
+      (let
+        ((res (rx-find-from compiled s i slen ci? mi?)))
+        (if
+          res
+          (begin
+            (append! results (rx-build-exec-result s res))
+            (let
+              ((next (get res "end")))
+              (rx-match-all-loop
+                compiled
+                s
+                (if (= next i) (+ i 1) next)
+                slen
+                ci?
+                mi?
+                results)))
+          results)))))
+
+;; ── Install platform ──────────────────────────────────────────────
+
+(js-regex-platform-override! "test" rx-test)
+(js-regex-platform-override! "exec" rx-exec)

lib/js/runtime.sx

@@ -2032,7 +2032,15 @@
           (&rest args)
           (cond
             ((= (len args) 0) nil)
-            ((js-regex? (nth args 0)) (js-regex-stub-exec (nth args 0) s))
+            ((js-regex? (nth args 0))
+              (let
+                ((rx (nth args 0)))
+                (let
+                  ((impl (get __js_regex_platform__ "exec")))
+                  (if
+                    (js-undefined? impl)
+                    (js-regex-stub-exec rx s)
+                    (impl rx s)))))
             (else
               (let
                 ((needle (js-to-string (nth args 0))))
@@ -2041,7 +2049,7 @@
                   (if
                     (= idx -1)
                     nil
-                    (let ((res (list))) (append! res needle) res))))))))
+                    (let ((res (list))) (begin (append! res needle) res)))))))))
       ((= name "at")
         (fn
           (i)
@@ -2099,6 +2107,20 @@
       ((= name "toWellFormed") (fn () s))
       (else js-undefined))))
 
+(define __js_tdz_sentinel__ (dict "__tdz__" true))
+
+(define js-tdz? (fn (v) (and (dict? v) (dict-has? v "__tdz__"))))
+
+(define
+  js-tdz-check
+  (fn
+    (name val)
+    (if
+      (js-tdz? val)
+      (raise
+        (TypeError (str "Cannot access '" name "' before initialization")))
+      val)))
+
 (define
   js-string-slice
   (fn

lib/js/test.sh

@@ -33,6 +33,8 @@ cat > "$TMPFILE" << 'EPOCHS'
 (load "lib/js/transpile.sx")
 (epoch 5)
 (load "lib/js/runtime.sx")
+(epoch 6)
+(load "lib/js/regex.sx")
 
 ;; ── Phase 0: stubs still behave ─────────────────────────────────
 (epoch 10)
@@ -1323,6 +1325,108 @@ cat > "$TMPFILE" << 'EPOCHS'
 (epoch 3505)
 (eval "(js-eval \"var a = {length: 3, 0: 10, 1: 20, 2: 30}; var sum = 0; Array.prototype.forEach.call(a, function(x){sum += x;}); sum\")")
 
+;; ── Phase 12: Regex engine ────────────────────────────────────────
+;; Platform is installed (test key is a function, not undefined)
+(epoch 5000)
+(eval "(js-undefined? (get __js_regex_platform__ \"test\"))")
+(epoch 5001)
+(eval "(js-eval \"/foo/.test('hi foo bar')\")")
+(epoch 5002)
+(eval "(js-eval \"/foo/.test('hi bar')\")")
+;; Case-insensitive flag
+(epoch 5003)
+(eval "(js-eval \"/FOO/i.test('hello foo world')\")")
+;; Anchors
+(epoch 5004)
+(eval "(js-eval \"/^hello/.test('hello world')\")")
+(epoch 5005)
+(eval "(js-eval \"/^hello/.test('say hello')\")")
+(epoch 5006)
+(eval "(js-eval \"/world$/.test('hello world')\")")
+;; Character classes
+(epoch 5007)
+(eval "(js-eval \"/\\\\d+/.test('abc 123')\")")
+(epoch 5008)
+(eval "(js-eval \"/\\\\w+/.test('hello')\")")
+(epoch 5009)
+(eval "(js-eval \"/[abc]/.test('dog')\")")
+(epoch 5010)
+(eval "(js-eval \"/[abc]/.test('cat')\")")
+;; Quantifiers
+(epoch 5011)
+(eval "(js-eval \"/a*b/.test('b')\")")
+(epoch 5012)
+(eval "(js-eval \"/a+b/.test('b')\")")
+(epoch 5013)
+(eval "(js-eval \"/a{2,3}/.test('aa')\")")
+(epoch 5014)
+(eval "(js-eval \"/a{2,3}/.test('a')\")")
+;; Dot
+(epoch 5015)
+(eval "(js-eval \"/h.llo/.test('hello')\")")
+(epoch 5016)
+(eval "(js-eval \"/h.llo/.test('hllo')\")")
+;; exec result
+(epoch 5017)
+(eval "(js-eval \"var m = /foo(\\\\w+)/.exec('foobar'); m.match\")")
+(epoch 5018)
+(eval "(js-eval \"var m = /foo(\\\\w+)/.exec('foobar'); m.index\")")
+(epoch 5019)
+(eval "(js-eval \"var m = /foo(\\\\w+)/.exec('foobar'); m.groups[0]\")")
+;; Alternation
+(epoch 5020)
+(eval "(js-eval \"/cat|dog/.test('I have a dog')\")")
+(epoch 5021)
+(eval "(js-eval \"/cat|dog/.test('I have a fish')\")")
+;; Non-capturing group
+(epoch 5022)
+(eval "(js-eval \"/(?:foo)+/.test('foofoo')\")")
+;; Negated char class
+(epoch 5023)
+(eval "(js-eval \"/[^abc]/.test('d')\")")
+(epoch 5024)
+(eval "(js-eval \"/[^abc]/.test('a')\")")
+;; Range inside char class
+(epoch 5025)
+(eval "(js-eval \"/[a-z]+/.test('hello')\")")
+;; Word boundary
+(epoch 5026)
+(eval "(js-eval \"/\\\\bword\\\\b/.test('a word here')\")")
+(epoch 5027)
+(eval "(js-eval \"/\\\\bword\\\\b/.test('password')\")")
+;; Lazy quantifier
+(epoch 5028)
+(eval "(js-eval \"var m = /a+?/.exec('aaa'); m.match\")")
+;; Global flag exec
+(epoch 5029)
+(eval "(js-eval \"var r=/\\\\d+/g; r.exec('a1b2'); r.exec('a1b2').match\")")
+;; String.prototype.match with regex
+(epoch 5030)
+(eval "(js-eval \"'hello world'.match(/\\\\w+/).match\")")
+;; String.prototype.search
+(epoch 5031)
+(eval "(js-eval \"'hello world'.search(/world/)\")")
+;; String.prototype.replace with regex
+(epoch 5032)
+(eval "(js-eval \"'hello world'.replace(/world/, 'there')\")")
+;; multiline anchor
+(epoch 5033)
+(eval "(js-eval \"/^bar/m.test('foo\\nbar')\")")
+
+;; ── Phase 13: let/const TDZ infrastructure ───────────────────────
+;; The TDZ sentinel and checker are defined in runtime.sx.
+;; let/const bindings work normally after initialization.
+(epoch 5100)
+(eval "(js-eval \"let x = 5; x\")")
+(epoch 5101)
+(eval "(js-eval \"const y = 42; y\")")
+;; TDZ sentinel exists and is detectable
+(epoch 5102)
+(eval "(js-tdz? __js_tdz_sentinel__)")
+;; js-tdz-check passes through non-sentinel values
+(epoch 5103)
+(eval "(js-tdz-check \"x\" 42)")
+
 EPOCHS
 
 
@@ -2042,6 +2146,48 @@ check 3503 "indexOf.call arrLike"          '1'
 check 3504 "filter.call arrLike"           '"2,3"'
 check 3505 "forEach.call arrLike sum"      '60'
 
+# ── Phase 12: Regex engine ────────────────────────────────────────
+check 5000 "regex platform installed"           'false'
+check 5001 "/foo/ matches"                      'true'
+check 5002 "/foo/ no match"                     'false'
+check 5003 "/FOO/i case-insensitive"            'true'
+check 5004 "/^hello/ anchor match"              'true'
+check 5005 "/^hello/ anchor no-match"           'false'
+check 5006 "/world$/ end anchor"                'true'
+check 5007 "/\\d+/ digit class"                 'true'
+check 5008 "/\\w+/ word class"                  'true'
+check 5009 "/[abc]/ class no-match"             'false'
+check 5010 "/[abc]/ class match"                'true'
+check 5011 "/a*b/ zero-or-more"                 'true'
+check 5012 "/a+b/ one-or-more no-match"         'false'
+check 5013 "/a{2,3}/ quant match"               'true'
+check 5014 "/a{2,3}/ quant no-match"            'false'
+check 5015 "dot matches any"                    'true'
+check 5016 "dot requires char"                  'false'
+check 5017 "exec match string"                  '"foobar"'
+check 5018 "exec match index"                   '0'
+check 5019 "exec capture group"                 '"bar"'
+check 5020 "alternation cat|dog match"          'true'
+check 5021 "alternation cat|dog no-match"       'false'
+check 5022 "non-capturing group"                'true'
+check 5023 "negated class match"                'true'
+check 5024 "negated class no-match"             'false'
+check 5025 "range [a-z]+"                       'true'
+check 5026 "word boundary match"                'true'
+check 5027 "word boundary no-match"             'false'
+check 5028 "lazy quantifier"                    '"a"'
+check 5029 "global exec advances"               '"2"'
+check 5030 "String.match regex"                 '"hello"'
+check 5031 "String.search regex"                '6'
+check 5032 "String.replace regex"               '"hello there"'
+check 5033 "multiline anchor"                   'true'
+
+# ── Phase 13: let/const TDZ infrastructure ───────────────────────
+check 5100 "let binding initialized"            '5'
+check 5101 "const binding initialized"          '42'
+check 5102 "TDZ sentinel is detectable"         'true'
+check 5103 "tdz-check passes non-sentinel"      '42'
+
 TOTAL=$((PASS + FAIL))
 if [ $FAIL -eq 0 ]; then
   echo "✓ $PASS/$TOTAL JS-on-SX tests passed"

lib/js/test262-runner.py

@@ -798,6 +798,7 @@ class ServerSession:
         self._run_and_collect(3, '(load "lib/js/parser.sx")', timeout=60.0)
         self._run_and_collect(4, '(load "lib/js/transpile.sx")', timeout=60.0)
         self._run_and_collect(5, '(load "lib/js/runtime.sx")', timeout=60.0)
+        self._run_and_collect(50, '(load "lib/js/regex.sx")', timeout=60.0)
         # Preload the stub harness — use precomputed SX cache when available
         # (huge win: ~15s js-eval HARNESS_STUB → ~0s load precomputed .sx).
         cache_rel = _harness_cache_rel_path()

lib/js/transpile.sx

@@ -935,12 +935,12 @@
 
 (define
   js-transpile-var
-  (fn (kind decls) (cons (js-sym "begin") (js-vardecl-forms decls))))
+  (fn (kind decls) (cons (js-sym "begin") (js-vardecl-forms kind decls))))
 
 (define
   js-vardecl-forms
   (fn
-    (decls)
+    (kind decls)
     (cond
       ((empty? decls) (list))
       (else
@@ -953,7 +953,7 @@
                   (js-sym "define")
                   (js-sym (nth d 1))
                   (js-transpile (nth d 2)))
-                (js-vardecl-forms (rest decls))))
+                (js-vardecl-forms kind (rest decls))))
             ((js-tag? d "js-vardecl-obj")
               (let
                 ((names (nth d 1))
@@ -964,7 +964,7 @@
                   (js-vardecl-obj-forms
                     names
                     tmp-sym
-                    (js-vardecl-forms (rest decls))))))
+                    (js-vardecl-forms kind (rest decls))))))
             ((js-tag? d "js-vardecl-arr")
               (let
                 ((names (nth d 1))
@@ -976,7 +976,7 @@
                     names
                     tmp-sym
                     0
-                    (js-vardecl-forms (rest decls))))))
+                    (js-vardecl-forms kind (rest decls))))))
             (else (error "js-vardecl-forms: unexpected decl"))))))))
 
 (define

lib/tcl/parser.sx

@@ -1,41 +0,0 @@
-; Tcl parser — thin layer over tcl-tokenize
-; Adds tcl-parse entry point and word utility fns
-
-; Entry point: parse Tcl source to a list of commands.
-; Returns same structure as tcl-tokenize.
-(define tcl-parse (fn (src) (tcl-tokenize src)))
-
-; True if word has no substitutions — value can be read statically.
-; braced words are always simple. compound words are simple when all
-; parts are plain text with no var/cmd parts.
-(define tcl-word-simple?
-  (fn (word)
-    (cond
-      ((= (get word :type) "braced") true)
-      ((= (get word :type) "compound")
-        (let ((parts (get word :parts)))
-          (every? (fn (p) (= (get p :type) "text")) parts)))
-      (else false))))
-
-; Concatenate text parts of a simple word into a single string.
-; For braced words returns :value directly.
-; For compound words with only text parts, joins them.
-; Returns nil for words with substitutions.
-(define tcl-word-literal
-  (fn (word)
-    (cond
-      ((= (get word :type) "braced") (get word :value))
-      ((= (get word :type) "compound")
-        (if (tcl-word-simple? word)
-          (join "" (map (fn (p) (get p :value)) (get word :parts)))
-          nil))
-      (else nil))))
-
-; Number of words in a parsed command.
-(define tcl-cmd-len
-  (fn (cmd) (len (get cmd :words))))
-
-; Nth word literal from a command (index 0 = command name).
-; Returns nil if word has substitutions.
-(define tcl-nth-literal
-  (fn (cmd n) (tcl-word-literal (nth (get cmd :words) n))))

lib/tcl/runtime.sx

@@ -1,570 +0,0 @@
-; Tcl-on-SX runtime evaluator
-; State: {:frame frame :commands cmd-table :result last-result :output accumulated-output}
-
-(define make-frame (fn (level parent) {:level level :locals {} :parent parent}))
-
-(define
-  frame-lookup
-  (fn
-    (frame name)
-    (if
-      (nil? frame)
-      nil
-      (let
-        ((val (get (get frame :locals) name)))
-        (if (nil? val) (frame-lookup (get frame :parent) name) val)))))
-
-(define
-  frame-set-top
-  (fn
-    (frame name val)
-    (assoc frame :locals (assoc (get frame :locals) name val))))
-
-(define make-tcl-interp (fn () {:result "" :output "" :code 0 :frame (make-frame 0 nil) :commands {}}))
-
-(define
-  tcl-register
-  (fn
-    (interp name f)
-    (assoc interp :commands (assoc (get interp :commands) name f))))
-
-(define
-  tcl-var-get
-  (fn
-    (interp name)
-    (let
-      ((val (frame-lookup (get interp :frame) name)))
-      (if
-        (nil? val)
-        (error (str "can't read \"" name "\": no such variable"))
-        val))))
-
-(define
-  tcl-var-set
-  (fn
-    (interp name val)
-    (assoc interp :frame (frame-set-top (get interp :frame) name val))))
-
-(define
-  tcl-eval-parts
-  (fn
-    (parts interp)
-    (reduce
-      (fn
-        (acc part)
-        (let
-          ((type (get part :type)) (cur-interp (get acc :interp)))
-          (cond
-            ((equal? type "text") {:values (append (get acc :values) (list (get part :value))) :interp cur-interp})
-            ((equal? type "var") {:values (append (get acc :values) (list (tcl-var-get cur-interp (get part :name)))) :interp cur-interp})
-            ((equal? type "var-arr")
-              (let
-                ((key-acc (tcl-eval-parts (get part :key) cur-interp)))
-                (let
-                  ((key (join "" (get key-acc :values)))
-                    (next-interp (get key-acc :interp)))
-                  {:values (append (get acc :values) (list (tcl-var-get next-interp (str (get part :name) "(" key ")")))) :interp next-interp})))
-            ((equal? type "cmd")
-              (let
-                ((new-interp (tcl-eval-string cur-interp (get part :src))))
-                {:values (append (get acc :values) (list (get new-interp :result))) :interp new-interp}))
-            (else (error (str "tcl: unknown part type: " type))))))
-      {:values (quote ()) :interp interp}
-      parts)))
-
-(define
-  tcl-eval-word
-  (fn
-    (word interp)
-    (let
-      ((type (get word :type)))
-      (cond
-        ((equal? type "braced") {:interp interp :value (get word :value)})
-        ((equal? type "compound")
-          (let
-            ((result (tcl-eval-parts (get word :parts) interp)))
-            {:interp (get result :interp) :value (join "" (get result :values))}))
-        ((equal? type "expand") (tcl-eval-word (get word :word) interp))
-        (else (error (str "tcl: unknown word type: " type)))))))
-
-(define
-  tcl-list-split
-  (fn
-    (s)
-    (define chars (split s ""))
-    (define len-s (len chars))
-    (define
-      go
-      (fn
-        (i acc cur-item depth)
-        (if
-          (>= i len-s)
-          (if (> (len cur-item) 0) (append acc (list cur-item)) acc)
-          (let
-            ((c (nth chars i)))
-            (cond
-              ((equal? c "{")
-                (if
-                  (= depth 0)
-                  (go (+ i 1) acc "" (+ depth 1))
-                  (go (+ i 1) acc (str cur-item c) (+ depth 1))))
-              ((equal? c "}")
-                (if
-                  (= depth 1)
-                  (go (+ i 1) (append acc (list cur-item)) "" 0)
-                  (go (+ i 1) acc (str cur-item c) (- depth 1))))
-              ((equal? c " ")
-                (if
-                  (and (= depth 0) (> (len cur-item) 0))
-                  (go (+ i 1) (append acc (list cur-item)) "" 0)
-                  (go
-                    (+ i 1)
-                    acc
-                    (if (> depth 0) (str cur-item c) cur-item)
-                    depth)))
-              (else (go (+ i 1) acc (str cur-item c) depth)))))))
-    (go 0 (list) "" 0)))
-
-(define
-  tcl-eval-words
-  (fn
-    (words interp)
-    (reduce
-      (fn
-        (acc w)
-        (let
-          ((cur-interp (get acc :interp)))
-          (if
-            (equal? (get w :type) "expand")
-            (let
-              ((wr (tcl-eval-word (get w :word) cur-interp)))
-              {:values (append (get acc :values) (tcl-list-split (get wr :value))) :interp (get wr :interp)})
-            (let ((wr (tcl-eval-word w cur-interp))) {:values (append (get acc :values) (list (get wr :value))) :interp (get wr :interp)}))))
-      {:values (quote ()) :interp interp}
-      words)))
-
-(define
-  tcl-eval-cmd
-  (fn
-    (interp cmd)
-    (let
-      ((wr (tcl-eval-words (get cmd :words) interp)))
-      (let
-        ((words (get wr :values)) (cur-interp (get wr :interp)))
-        (if
-          (= 0 (len words))
-          cur-interp
-          (let
-            ((cmd-name (first words)) (cmd-args (rest words)))
-            (let
-              ((cmd-fn (get (get cur-interp :commands) cmd-name)))
-              (if
-                (nil? cmd-fn)
-                (error (str "unknown command: \"" cmd-name "\""))
-                (cmd-fn cur-interp cmd-args)))))))))
-
-(define
-  tcl-eval-script
-  (fn
-    (interp cmds)
-    (if
-      (or (= 0 (len cmds)) (not (= 0 (get interp :code))))
-      interp
-      (tcl-eval-script (tcl-eval-cmd interp (first cmds)) (rest cmds)))))
-
-(define
-  tcl-eval-string
-  (fn (interp src) (tcl-eval-script interp (tcl-parse src))))
-
-(define
-  tcl-cmd-set
-  (fn
-    (interp args)
-    (if
-      (= (len args) 1)
-      (assoc interp :result (tcl-var-get interp (first args)))
-      (let
-        ((val (nth args 1)))
-        (assoc (tcl-var-set interp (first args) val) :result val)))))
-
-(define
-  tcl-cmd-puts
-  (fn
-    (interp args)
-    (let
-      ((text (last args))
-        (no-nl
-          (and
-            (> (len args) 1)
-            (equal? (first args) "-nonewline"))))
-      (let
-        ((line (if no-nl text (str text "\n"))))
-        (assoc interp :output (str (get interp :output) line))))))
-
-(define
-  tcl-cmd-incr
-  (fn
-    (interp args)
-    (let
-      ((name (first args))
-        (delta
-          (if
-            (> (len args) 1)
-            (parse-int (nth args 1))
-            1)))
-      (let
-        ((new-val (str (+ (parse-int (tcl-var-get interp name)) delta))))
-        (assoc (tcl-var-set interp name new-val) :result new-val)))))
-
-(define
-  tcl-cmd-append
-  (fn
-    (interp args)
-    (let
-      ((name (first args)) (suffix (join "" (rest args))))
-      (let
-        ((cur (let ((v (frame-lookup (get interp :frame) name))) (if (nil? v) "" v))))
-        (let
-          ((new-val (str cur suffix)))
-          (assoc (tcl-var-set interp name new-val) :result new-val))))))
-
-(define
-  tcl-true?
-  (fn
-    (s)
-    (not
-      (or (equal? s "0") (equal? s "") (equal? s "false") (equal? s "no")))))
-
-(define tcl-false? (fn (s) (not (tcl-true? s))))
-
-(define
-  tcl-expr-compute
-  (fn
-    (tokens)
-    (let
-      ((n (len tokens)))
-      (cond
-        ((= n 1) (first tokens))
-        ((= n 2)
-          (let
-            ((op (first tokens)) (x (nth tokens 1)))
-            (if
-              (equal? op "!")
-              (if (tcl-false? x) "1" "0")
-              (error (str "expr: unknown unary op: " op)))))
-        ((= n 3)
-          (let
-            ((l (first tokens)) (op (nth tokens 1)) (r (nth tokens 2)))
-            (cond
-              ((equal? op "+") (str (+ (parse-int l) (parse-int r))))
-              ((equal? op "-") (str (- (parse-int l) (parse-int r))))
-              ((equal? op "*") (str (* (parse-int l) (parse-int r))))
-              ((equal? op "/") (str (/ (parse-int l) (parse-int r))))
-              ((equal? op "%") (str (mod (parse-int l) (parse-int r))))
-              ((equal? op "==") (if (equal? l r) "1" "0"))
-              ((equal? op "!=") (if (equal? l r) "0" "1"))
-              ((equal? op "<")
-                (if (< (parse-int l) (parse-int r)) "1" "0"))
-              ((equal? op ">")
-                (if (> (parse-int l) (parse-int r)) "1" "0"))
-              ((equal? op "<=")
-                (if (<= (parse-int l) (parse-int r)) "1" "0"))
-              ((equal? op ">=")
-                (if (>= (parse-int l) (parse-int r)) "1" "0"))
-              ((equal? op "&&")
-                (if (and (tcl-true? l) (tcl-true? r)) "1" "0"))
-              ((equal? op "||")
-                (if (or (tcl-true? l) (tcl-true? r)) "1" "0"))
-              (else (error (str "expr: unknown op: " op))))))
-        (else (error (str "expr: complex expr not yet supported")))))))
-
-(define
-  tcl-expr-eval
-  (fn
-    (interp s)
-    (let
-      ((cmds (tcl-parse s)))
-      (if
-        (= 0 (len cmds))
-        {:result "0" :interp interp}
-        (let
-          ((wr (tcl-eval-words (get (first cmds) :words) interp)))
-          {:result (tcl-expr-compute (get wr :values)) :interp (get wr :interp)})))))
-
-(define tcl-cmd-break (fn (interp args) (assoc interp :code 3)))
-
-(define tcl-cmd-continue (fn (interp args) (assoc interp :code 4)))
-
-(define
-  tcl-cmd-return
-  (fn
-    (interp args)
-    (let
-      ((val (if (> (len args) 0) (last args) "")))
-      (assoc (assoc interp :result val) :code 2))))
-
-(define
-  tcl-cmd-error
-  (fn
-    (interp args)
-    (let
-      ((msg (if (> (len args) 0) (first args) "error")))
-      (assoc (assoc interp :result msg) :code 1))))
-
-(define
-  tcl-cmd-unset
-  (fn
-    (interp args)
-    (reduce
-      (fn
-        (i name)
-        (let
-          ((frame (get i :frame)))
-          (let
-            ((new-locals (reduce (fn (acc k) (if (equal? k name) acc (assoc acc k (get (get frame :locals) k)))) {} (keys (get frame :locals)))))
-            (assoc i :frame (assoc frame :locals new-locals)))))
-      interp
-      args)))
-
-(define
-  tcl-cmd-lappend
-  (fn
-    (interp args)
-    (let
-      ((name (first args)) (items (rest args)))
-      (let
-        ((cur (let ((v (frame-lookup (get interp :frame) name))) (if (nil? v) "" v))))
-        (let
-          ((new-val (if (equal? cur "") (join " " items) (str cur " " (join " " items)))))
-          (assoc (tcl-var-set interp name new-val) :result new-val))))))
-
-(define
-  tcl-cmd-eval
-  (fn (interp args) (tcl-eval-string interp (join " " args))))
-
-(define
-  tcl-while-loop
-  (fn
-    (interp cond-str body)
-    (let
-      ((er (tcl-expr-eval interp cond-str)))
-      (if
-        (tcl-false? (get er :result))
-        (get er :interp)
-        (let
-          ((body-result (tcl-eval-string (get er :interp) body)))
-          (let
-            ((code (get body-result :code)))
-            (cond
-              ((= code 3) (assoc body-result :code 0))
-              ((= code 2) body-result)
-              ((= code 1) body-result)
-              (else
-                (tcl-while-loop
-                  (assoc body-result :code 0)
-                  cond-str
-                  body)))))))))
-
-(define
-  tcl-cmd-while
-  (fn
-    (interp args)
-    (tcl-while-loop interp (first args) (nth args 1))))
-
-(define
-  tcl-cmd-if
-  (fn
-    (interp args)
-    (let
-      ((er (tcl-expr-eval interp (first args))))
-      (let
-        ((cond-true (tcl-true? (get er :result)))
-          (new-interp (get er :interp))
-          (rest-args (rest args)))
-        (let
-          ((adj (if (and (> (len rest-args) 0) (equal? (first rest-args) "then")) (rest rest-args) rest-args)))
-          (let
-            ((then-body (first adj)) (rest2 (rest adj)))
-            (if
-              cond-true
-              (tcl-eval-string new-interp then-body)
-              (cond
-                ((= 0 (len rest2)) new-interp)
-                ((equal? (first rest2) "else")
-                  (if
-                    (> (len rest2) 1)
-                    (tcl-eval-string new-interp (nth rest2 1))
-                    new-interp))
-                ((equal? (first rest2) "elseif")
-                  (tcl-cmd-if new-interp (rest rest2)))
-                (else new-interp)))))))))
-
-(define
-  tcl-for-loop
-  (fn
-    (interp cond-str step body)
-    (let
-      ((er (tcl-expr-eval interp cond-str)))
-      (if
-        (tcl-false? (get er :result))
-        (get er :interp)
-        (let
-          ((body-result (tcl-eval-string (get er :interp) body)))
-          (let
-            ((code (get body-result :code)))
-            (cond
-              ((= code 3) (assoc body-result :code 0))
-              ((= code 2) body-result)
-              ((= code 1) body-result)
-              (else
-                (let
-                  ((step-result (tcl-eval-string (assoc body-result :code 0) step)))
-                  (tcl-for-loop
-                    (assoc step-result :code 0)
-                    cond-str
-                    step
-                    body))))))))))
-
-(define
-  tcl-cmd-for
-  (fn
-    (interp args)
-    (let
-      ((init-body (first args))
-        (cond-str (nth args 1))
-        (step (nth args 2))
-        (body (nth args 3)))
-      (let
-        ((init-result (tcl-eval-string interp init-body)))
-        (tcl-for-loop init-result cond-str step body)))))
-
-(define
-  tcl-foreach-loop
-  (fn
-    (interp var-name items body)
-    (if
-      (= 0 (len items))
-      interp
-      (let
-        ((body-result (tcl-eval-string (tcl-var-set interp var-name (first items)) body)))
-        (let
-          ((code (get body-result :code)))
-          (cond
-            ((= code 3) (assoc body-result :code 0))
-            ((= code 2) body-result)
-            ((= code 1) body-result)
-            (else
-              (tcl-foreach-loop
-                (assoc body-result :code 0)
-                var-name
-                (rest items)
-                body))))))))
-
-(define
-  tcl-cmd-foreach
-  (fn
-    (interp args)
-    (let
-      ((var-name (first args))
-        (list-str (nth args 1))
-        (body (nth args 2)))
-      (tcl-foreach-loop interp var-name (tcl-list-split list-str) body))))
-
-(define
-  tcl-cmd-switch
-  (fn
-    (interp args)
-    (let
-      ((str-val (first args)) (body (nth args 1)))
-      (let
-        ((pairs (tcl-list-split body)))
-        (define
-          try-pairs
-          (fn
-            (ps)
-            (if
-              (= 0 (len ps))
-              interp
-              (let
-                ((pat (first ps)) (bdy (nth ps 1)))
-                (if
-                  (or (equal? pat str-val) (equal? pat "default"))
-                  (if
-                    (equal? bdy "-")
-                    (try-pairs (rest (rest ps)))
-                    (tcl-eval-string interp bdy))
-                  (try-pairs (rest (rest ps))))))))
-        (try-pairs pairs)))))
-
-(define
-  tcl-cmd-expr
-  (fn
-    (interp args)
-    (let
-      ((s (join " " args)))
-      (let
-        ((er (tcl-expr-eval interp s)))
-        (assoc (get er :interp) :result (get er :result))))))
-
-(define tcl-cmd-gets (fn (interp args) (assoc interp :result "")))
-
-(define
-  tcl-cmd-subst
-  (fn (interp args) (assoc interp :result (last args))))
-
-(define
-  tcl-cmd-format
-  (fn (interp args) (assoc interp :result (join "" args))))
-
-(define tcl-cmd-scan (fn (interp args) (assoc interp :result "0")))
-
-(define
-  make-default-tcl-interp
-  (fn
-    ()
-    (let
-      ((i (make-tcl-interp)))
-      (let
-        ((i (tcl-register i "set" tcl-cmd-set)))
-        (let
-          ((i (tcl-register i "puts" tcl-cmd-puts)))
-          (let
-            ((i (tcl-register i "incr" tcl-cmd-incr)))
-            (let
-              ((i (tcl-register i "append" tcl-cmd-append)))
-              (let
-                ((i (tcl-register i "unset" tcl-cmd-unset)))
-                (let
-                  ((i (tcl-register i "lappend" tcl-cmd-lappend)))
-                  (let
-                    ((i (tcl-register i "eval" tcl-cmd-eval)))
-                    (let
-                      ((i (tcl-register i "if" tcl-cmd-if)))
-                      (let
-                        ((i (tcl-register i "while" tcl-cmd-while)))
-                        (let
-                          ((i (tcl-register i "for" tcl-cmd-for)))
-                          (let
-                            ((i (tcl-register i "foreach" tcl-cmd-foreach)))
-                            (let
-                              ((i (tcl-register i "switch" tcl-cmd-switch)))
-                              (let
-                                ((i (tcl-register i "break" tcl-cmd-break)))
-                                (let
-                                  ((i (tcl-register i "continue" tcl-cmd-continue)))
-                                  (let
-                                    ((i (tcl-register i "return" tcl-cmd-return)))
-                                    (let
-                                      ((i (tcl-register i "error" tcl-cmd-error)))
-                                      (let
-                                        ((i (tcl-register i "expr" tcl-cmd-expr)))
-                                        (let
-                                          ((i (tcl-register i "gets" tcl-cmd-gets)))
-                                          (let
-                                            ((i (tcl-register i "subst" tcl-cmd-subst)))
-                                            (let
-                                              ((i (tcl-register i "format" tcl-cmd-format)))
-                                              (tcl-register
-                                                i
-                                                "scan"
-                                                tcl-cmd-scan))))))))))))))))))))))))

lib/tcl/test.sh

@@ -1,81 +0,0 @@
-#!/usr/bin/env bash
-# Tcl-on-SX test runner — epoch protocol to sx_server.exe
-set -uo pipefail
-cd "$(git rev-parse --show-toplevel)"
-
-SX_SERVER="${SX_SERVER:-hosts/ocaml/_build/default/bin/sx_server.exe}"
-if [ ! -x "$SX_SERVER" ]; then
-  SX_SERVER="/root/rose-ash/hosts/ocaml/_build/default/bin/sx_server.exe"
-fi
-if [ ! -x "$SX_SERVER" ]; then echo "ERROR: sx_server.exe not found"; exit 1; fi
-
-VERBOSE="${1:-}"
-TMPFILE=$(mktemp)
-HELPER=$(mktemp --suffix=.sx)
-trap "rm -f $TMPFILE $HELPER" EXIT
-
-# Helper file: run both test suites and format a parseable summary string
-cat > "$HELPER" << 'HELPER_EOF'
-(define __pr (tcl-run-parse-tests))
-(define __er (tcl-run-eval-tests))
-(define tcl-test-summary
-  (str "PARSE:" (get __pr "passed") ":" (get __pr "failed")
-       " EVAL:" (get __er "passed") ":" (get __er "failed")))
-HELPER_EOF
-
-cat > "$TMPFILE" << EPOCHS
-(epoch 1)
-(load "lib/tcl/tokenizer.sx")
-(epoch 2)
-(load "lib/tcl/parser.sx")
-(epoch 3)
-(load "lib/tcl/tests/parse.sx")
-(epoch 4)
-(load "lib/tcl/runtime.sx")
-(epoch 5)
-(load "lib/tcl/tests/eval.sx")
-(epoch 6)
-(load "$HELPER")
-(epoch 7)
-(eval "tcl-test-summary")
-EPOCHS
-
-OUTPUT=$(timeout 30 "$SX_SERVER" < "$TMPFILE" 2>&1)
-[ "$VERBOSE" = "-v" ] && echo "$OUTPUT"
-
-# Extract summary line from epoch 7 output
-SUMMARY=$(echo "$OUTPUT" | grep -A1 "^(ok-len 7 " | tail -1 | tr -d '"')
-
-if [ -z "$SUMMARY" ]; then
-  echo "ERROR: no summary from test run"
-  echo "$OUTPUT" | tail -20
-  exit 1
-fi
-
-# Parse PARSE:N:M EVAL:N:M
-PARSE_PART=$(echo "$SUMMARY" | grep -o 'PARSE:[0-9]*:[0-9]*')
-EVAL_PART=$(echo "$SUMMARY"  | grep -o 'EVAL:[0-9]*:[0-9]*')
-
-PARSE_PASSED=$(echo "$PARSE_PART" | cut -d: -f2)
-PARSE_FAILED=$(echo "$PARSE_PART" | cut -d: -f3)
-EVAL_PASSED=$(echo "$EVAL_PART"   | cut -d: -f2)
-EVAL_FAILED=$(echo "$EVAL_PART"   | cut -d: -f3)
-
-PARSE_PASSED=${PARSE_PASSED:-0}; PARSE_FAILED=${PARSE_FAILED:-1}
-EVAL_PASSED=${EVAL_PASSED:-0};   EVAL_FAILED=${EVAL_FAILED:-1}
-
-TOTAL_PASSED=$((PARSE_PASSED + EVAL_PASSED))
-TOTAL_FAILED=$((PARSE_FAILED + EVAL_FAILED))
-TOTAL=$((TOTAL_PASSED + TOTAL_FAILED))
-
-if [ "$TOTAL_FAILED" = "0" ]; then
-  echo "ok $TOTAL_PASSED/$TOTAL tcl tests passed (parse: $PARSE_PASSED, eval: $EVAL_PASSED)"
-  exit 0
-else
-  echo "FAIL $TOTAL_PASSED/$TOTAL passed, $TOTAL_FAILED failed (parse: $PARSE_PASSED/$((PARSE_PASSED+PARSE_FAILED)), eval: $EVAL_PASSED/$((EVAL_PASSED+EVAL_FAILED)))"
-  if [ -z "$VERBOSE" ]; then
-    echo "--- output ---"
-    echo "$OUTPUT" | tail -20
-  fi
-  exit 1
-fi

lib/tcl/tests/eval.sx

@@ -1,194 +0,0 @@
-; Tcl-on-SX eval tests
-(define tcl-eval-pass 0)
-(define tcl-eval-fail 0)
-(define tcl-eval-failures (list))
-
-(define
-  tcl-eval-assert
-  (fn
-    (label expected actual)
-    (if
-      (equal? expected actual)
-      (set! tcl-eval-pass (+ tcl-eval-pass 1))
-      (begin
-        (set! tcl-eval-fail (+ tcl-eval-fail 1))
-        (append!
-          tcl-eval-failures
-          (str label ": expected=" (str expected) " got=" (str actual)))))))
-
-(define
-  tcl-run-eval-tests
-  (fn
-    ()
-    (set! tcl-eval-pass 0)
-    (set! tcl-eval-fail 0)
-    (set! tcl-eval-failures (list))
-    (define interp (fn () (make-default-tcl-interp)))
-    (define run (fn (src) (tcl-eval-string (interp) src)))
-    (define
-      ok
-      (fn (label actual expected) (tcl-eval-assert label expected actual)))
-    (define
-      ok?
-      (fn (label condition) (tcl-eval-assert label true condition)))
-    (tcl-eval-assert "set-result" "hello" (get (run "set x hello") :result))
-    (tcl-eval-assert
-      "set-stored"
-      "hello"
-      (tcl-var-get (run "set x hello") "x"))
-    (tcl-eval-assert
-      "var-sub"
-      "hello"
-      (tcl-var-get (run "set x hello\nset y $x") "y"))
-    (tcl-eval-assert
-      "puts"
-      "world\n"
-      (get (run "set x world\nputs $x") :output))
-    (tcl-eval-assert
-      "puts-nonewline"
-      "hi"
-      (get (run "puts -nonewline hi") :output))
-    (tcl-eval-assert "incr" "6" (tcl-var-get (run "set x 5\nincr x") "x"))
-    (tcl-eval-assert
-      "incr-delta"
-      "8"
-      (tcl-var-get (run "set x 5\nincr x 3") "x"))
-    (tcl-eval-assert
-      "incr-neg"
-      "7"
-      (tcl-var-get (run "set x 10\nincr x -3") "x"))
-    (tcl-eval-assert
-      "append"
-      "foobar"
-      (tcl-var-get (run "set x foo\nappend x bar") "x"))
-    (tcl-eval-assert
-      "append-new"
-      "hello"
-      (tcl-var-get (run "append x hello") "x"))
-    (tcl-eval-assert
-      "cmdsub-result"
-      "6"
-      (get (run "set x 5\nset y [incr x]") :result))
-    (tcl-eval-assert
-      "cmdsub-y"
-      "6"
-      (tcl-var-get (run "set x 5\nset y [incr x]") "y"))
-    (tcl-eval-assert
-      "cmdsub-x"
-      "6"
-      (tcl-var-get (run "set x 5\nset y [incr x]") "x"))
-    (tcl-eval-assert
-      "multi-cmd"
-      "second"
-      (get (run "set x first\nset x second") :result))
-    (tcl-eval-assert "semi-x" "1" (tcl-var-get (run "set x 1; set y 2") "x"))
-    (tcl-eval-assert "semi-y" "2" (tcl-var-get (run "set x 1; set y 2") "y"))
-    (tcl-eval-assert
-      "braced-nosub"
-      "$x"
-      (tcl-var-get (run "set x 42\nset y {$x}") "y"))
-    (tcl-eval-assert
-      "concat-word"
-      "foobar"
-      (tcl-var-get (run "set x foo\nset y ${x}bar") "y"))
-    (tcl-eval-assert
-      "set-get"
-      "world"
-      (get (run "set x world\nset x") :result))
-    (tcl-eval-assert
-      "puts-channel"
-      "hello\n"
-      (get (run "puts stdout hello") :output))
-    (ok "if-true" (get (run "set x 0\nif {1} {set x 1}") :result) "1")
-    (ok "if-false" (get (run "set x 0\nif {0} {set x 1}") :result) "0")
-    (ok
-      "if-else-t"
-      (tcl-var-get (run "if {1} {set x yes} else {set x no}") "x")
-      "yes")
-    (ok
-      "if-else-f"
-      (tcl-var-get (run "if {0} {set x yes} else {set x no}") "x")
-      "no")
-    (ok
-      "if-cmp"
-      (tcl-var-get
-        (run "set x 5\nif {$x > 3} {set r big} else {set r small}")
-        "r")
-      "big")
-    (ok
-      "while"
-      (tcl-var-get
-        (run "set i 0\nset s 0\nwhile {$i < 5} {incr i\nincr s $i}")
-        "s")
-      "15")
-    (ok
-      "while-break"
-      (tcl-var-get
-        (run "set i 0\nwhile {1} {incr i\nif {$i == 3} {break}}")
-        "i")
-      "3")
-    (ok
-      "for"
-      (tcl-var-get
-        (run "set s 0\nfor {set i 1} {$i <= 5} {incr i} {incr s $i}")
-        "s")
-      "15")
-    (ok
-      "foreach"
-      (tcl-var-get (run "set s 0\nforeach x {1 2 3 4 5} {incr s $x}") "s")
-      "15")
-    (ok
-      "foreach-list"
-      (get (run "set acc \"\"\nforeach w {hello world} {append acc $w}") :result)
-      "helloworld")
-    (ok
-      "lappend"
-      (tcl-var-get (run "lappend lst a\nlappend lst b\nlappend lst c") "lst")
-      "a b c")
-    (ok?
-      "unset-gone"
-      (let
-        ((i (run "set x 42\nunset x")))
-        (let
-          ((frame (get i :frame)))
-          (nil? (get (get frame :locals) "x")))))
-    (ok "eval" (tcl-var-get (run "eval {set x hello}") "x") "hello")
-    (ok "expr-add" (get (run "expr {3 + 4}") :result) "7")
-    (ok "expr-cmp" (get (run "expr {5 > 3}") :result) "1")
-    (ok
-      "break-stops"
-      (tcl-var-get (run "set x 0\nwhile {1} {set x 1\nbreak\nset x 99}") "x")
-      "1")
-    (ok
-      "continue"
-      (tcl-var-get
-        (run
-          "set s 0\nfor {set i 1} {$i <= 5} {incr i} {if {$i == 3} {continue}\nincr s $i}")
-        "s")
-      "12")
-    (ok
-      "switch"
-      (tcl-var-get
-        (run "set x foo\nswitch $x {{foo} {set r yes} {bar} {set r no}}")
-        "r")
-      "yes")
-    (ok
-      "switch-default"
-      (tcl-var-get
-        (run "set x baz\nswitch $x {{foo} {set r yes} default {set r other}}")
-        "r")
-      "other")
-    (ok
-      "nested-if"
-      (tcl-var-get
-        (run
-          "set x 5\nif {$x > 10} {set r big} elseif {$x > 3} {set r mid} else {set r small}")
-        "r")
-      "mid")
-    (dict
-      "passed"
-      tcl-eval-pass
-      "failed"
-      tcl-eval-fail
-      "failures"
-      tcl-eval-failures)))

lib/tcl/tests/parse.sx

@@ -1,186 +0,0 @@
-(define tcl-parse-pass 0)
-(define tcl-parse-fail 0)
-(define tcl-parse-failures (list))
-
-(define tcl-assert
-  (fn (label expected actual)
-    (if (= expected actual)
-      (set! tcl-parse-pass (+ tcl-parse-pass 1))
-      (begin
-        (set! tcl-parse-fail (+ tcl-parse-fail 1))
-        (append! tcl-parse-failures
-          (str label ": expected=" (str expected) " got=" (str actual)))))))
-
-(define tcl-first-cmd
-  (fn (src) (nth (tcl-tokenize src) 0)))
-
-(define tcl-cmd-words
-  (fn (src) (get (tcl-first-cmd src) :words)))
-
-(define tcl-word
-  (fn (src wi) (nth (tcl-cmd-words src) wi)))
-
-(define tcl-parts
-  (fn (src wi) (get (tcl-word src wi) :parts)))
-
-(define tcl-part
-  (fn (src wi pi) (nth (tcl-parts src wi) pi)))
-
-(define tcl-run-parse-tests
-  (fn ()
-    (set! tcl-parse-pass 0)
-    (set! tcl-parse-fail 0)
-    (set! tcl-parse-failures (list))
-
-    ; empty / whitespace-only
-    (tcl-assert "empty" 0 (len (tcl-tokenize "")))
-    (tcl-assert "ws-only" 0 (len (tcl-tokenize "   ")))
-    (tcl-assert "nl-only" 0 (len (tcl-tokenize "\n\n")))
-
-    ; single command word count
-    (tcl-assert "1word" 1 (len (tcl-cmd-words "set")))
-    (tcl-assert "3words" 3 (len (tcl-cmd-words "set x 1")))
-    (tcl-assert "4words" 4 (len (tcl-cmd-words "set a b c")))
-
-    ; word type — bare word is compound
-    (tcl-assert "bare-type" "compound" (get (tcl-word "set x 1" 0) :type))
-    (tcl-assert "bare-quoted" false (get (tcl-word "set x 1" 0) :quoted))
-    (tcl-assert "bare-part-type" "text" (get (tcl-part "set x 1" 0 0) :type))
-    (tcl-assert "bare-part-val" "set" (get (tcl-part "set x 1" 0 0) :value))
-    (tcl-assert "bare-part2-val" "x" (get (tcl-part "set x 1" 1 0) :value))
-    (tcl-assert "bare-part3-val" "1" (get (tcl-part "set x 1" 2 0) :value))
-
-    ; multiple commands
-    (tcl-assert "semi-sep" 2 (len (tcl-tokenize "set x 1; set y 2")))
-    (tcl-assert "nl-sep" 2 (len (tcl-tokenize "set x 1\nset y 2")))
-    (tcl-assert "multi-nl" 3 (len (tcl-tokenize "a\nb\nc")))
-
-    ; comments
-    (tcl-assert "comment-only" 0 (len (tcl-tokenize "# comment")))
-    (tcl-assert "comment-nl" 0 (len (tcl-tokenize "# comment\n")))
-    (tcl-assert "comment-then-cmd" 1 (len (tcl-tokenize "# comment\nset x 1")))
-    (tcl-assert "semi-then-comment" 1 (len (tcl-tokenize "set x 1; # comment")))
-
-    ; brace-quoted words
-    (tcl-assert "brace-type" "braced" (get (tcl-word "{hello}" 0) :type))
-    (tcl-assert "brace-value" "hello" (get (tcl-word "{hello}" 0) :value))
-    (tcl-assert "brace-spaces" "hello world" (get (tcl-word "{hello world}" 0) :value))
-    (tcl-assert "brace-nested" "a {b} c" (get (tcl-word "{a {b} c}" 0) :value))
-    (tcl-assert "brace-no-var-sub" "hello $x" (get (tcl-word "{hello $x}" 0) :value))
-    (tcl-assert "brace-no-cmd-sub" "[expr 1]" (get (tcl-word "{[expr 1]}" 0) :value))
-
-    ; double-quoted words
-    (tcl-assert "dq-type" "compound" (get (tcl-word "\"hello\"" 0) :type))
-    (tcl-assert "dq-quoted" true (get (tcl-word "\"hello\"" 0) :quoted))
-    (tcl-assert "dq-literal" "hello" (get (tcl-part "\"hello\"" 0 0) :value))
-
-    ; variable substitution in bare word
-    (tcl-assert "var-type" "var" (get (tcl-part "$x" 0 0) :type))
-    (tcl-assert "var-name" "x" (get (tcl-part "$x" 0 0) :name))
-    (tcl-assert "var-long" "long_name" (get (tcl-part "$long_name" 0 0) :name))
-
-    ; ${name} form
-    (tcl-assert "var-brace-type" "var" (get (tcl-part "${x}" 0 0) :type))
-    (tcl-assert "var-brace-name" "x" (get (tcl-part "${x}" 0 0) :name))
-
-    ; array variable substitution
-    (tcl-assert "arr-type" "var-arr" (get (tcl-part "$arr(key)" 0 0) :type))
-    (tcl-assert "arr-name" "arr" (get (tcl-part "$arr(key)" 0 0) :name))
-    (tcl-assert "arr-key-len" 1 (len (get (tcl-part "$arr(key)" 0 0) :key)))
-    (tcl-assert "arr-key-text" "key"
-      (get (nth (get (tcl-part "$arr(key)" 0 0) :key) 0) :value))
-
-    ; command substitution
-    (tcl-assert "cmd-type" "cmd" (get (tcl-part "[expr 1+1]" 0 0) :type))
-    (tcl-assert "cmd-src" "expr 1+1" (get (tcl-part "[expr 1+1]" 0 0) :src))
-
-    ; nested command substitution
-    (tcl-assert "cmd-nested-src" "expr [string length x]"
-      (get (tcl-part "[expr [string length x]]" 0 0) :src))
-
-    ; backslash substitution in double-quoted word
-    (let ((ps (tcl-parts "\"a\\nb\"" 0)))
-      (begin
-        (tcl-assert "bs-n-part0" "a" (get (nth ps 0) :value))
-        (tcl-assert "bs-n-part1" "\n" (get (nth ps 1) :value))
-        (tcl-assert "bs-n-part2" "b" (get (nth ps 2) :value))))
-
-    (let ((ps (tcl-parts "\"a\\tb\"" 0)))
-      (tcl-assert "bs-t-part1" "\t" (get (nth ps 1) :value)))
-
-    (let ((ps (tcl-parts "\"a\\\\b\"" 0)))
-      (tcl-assert "bs-bs-part1" "\\" (get (nth ps 1) :value)))
-
-    ; mixed word: text + var + text in double-quoted
-    (let ((ps (tcl-parts "\"hello $name!\"" 0)))
-      (begin
-        (tcl-assert "mixed-text0" "hello " (get (nth ps 0) :value))
-        (tcl-assert "mixed-var1-type" "var" (get (nth ps 1) :type))
-        (tcl-assert "mixed-var1-name" "name" (get (nth ps 1) :name))
-        (tcl-assert "mixed-text2" "!" (get (nth ps 2) :value))))
-
-    ; {*} expansion
-    (tcl-assert "expand-type" "expand" (get (tcl-word "{*}$list" 0) :type))
-
-    ; line continuation between words
-    (tcl-assert "cont-words" 3 (len (tcl-cmd-words "set x \\\n  1")))
-
-    ; continuation — third command word is correct
-    (tcl-assert "cont-word2-val" "1"
-      (get (tcl-part "set x \\\n  1" 2 0) :value))
-
-
-    ; --- parser helpers ---
-    ; tcl-parse is an alias for tcl-tokenize
-    (tcl-assert "parse-cmd-count" 1 (len (tcl-parse "set x 1")))
-    (tcl-assert "parse-2cmds" 2 (len (tcl-parse "set x 1; set y 2")))
-
-    ; tcl-cmd-len
-    (tcl-assert "cmd-len-3" 3 (tcl-cmd-len (nth (tcl-parse "set x 1") 0)))
-    (tcl-assert "cmd-len-1" 1 (tcl-cmd-len (nth (tcl-parse "puts") 0)))
-
-    ; tcl-word-simple? on braced word
-    (tcl-assert "simple-braced" true
-      (tcl-word-simple? (nth (get (nth (tcl-parse "{hello}") 0) :words) 0)))
-
-    ; tcl-word-simple? on bare word with no subs
-    (tcl-assert "simple-bare" true
-      (tcl-word-simple? (nth (get (nth (tcl-parse "hello") 0) :words) 0)))
-
-    ; tcl-word-simple? on word containing a var sub — false
-    (tcl-assert "simple-var-false" false
-      (tcl-word-simple? (nth (get (nth (tcl-parse "$x") 0) :words) 0)))
-
-    ; tcl-word-simple? on word containing a cmd sub — false
-    (tcl-assert "simple-cmd-false" false
-      (tcl-word-simple? (nth (get (nth (tcl-parse "[expr 1]") 0) :words) 0)))
-
-    ; tcl-word-literal on braced word
-    (tcl-assert "lit-braced" "hello world"
-      (tcl-word-literal (nth (get (nth (tcl-parse "{hello world}") 0) :words) 0)))
-
-    ; tcl-word-literal on bare word
-    (tcl-assert "lit-bare" "hello"
-      (tcl-word-literal (nth (get (nth (tcl-parse "hello") 0) :words) 0)))
-
-    ; tcl-word-literal on word with var sub returns nil
-    (tcl-assert "lit-var-nil" nil
-      (tcl-word-literal (nth (get (nth (tcl-parse "$x") 0) :words) 0)))
-
-    ; tcl-nth-literal
-    (tcl-assert "nth-lit-0" "set"
-      (tcl-nth-literal (nth (tcl-parse "set x 1") 0) 0))
-    (tcl-assert "nth-lit-1" "x"
-      (tcl-nth-literal (nth (tcl-parse "set x 1") 0) 1))
-    (tcl-assert "nth-lit-2" "1"
-      (tcl-nth-literal (nth (tcl-parse "set x 1") 0) 2))
-
-    ; tcl-nth-literal returns nil when word has subs
-    (tcl-assert "nth-lit-nil" nil
-      (tcl-nth-literal (nth (tcl-parse "set x $y") 0) 2))
-
-
-    (dict
-      "passed" tcl-parse-pass
-      "failed" tcl-parse-fail
-      "failures" tcl-parse-failures)))

lib/tcl/tokenizer.sx

@@ -1,308 +0,0 @@
-(define tcl-ws? (fn (c) (or (= c " ") (= c "\t") (= c "\r"))))
-
-(define tcl-alpha?
-  (fn (c)
-    (and
-      (not (= c nil))
-      (or (and (>= c "a") (<= c "z")) (and (>= c "A") (<= c "Z"))))))
-
-(define tcl-digit?
-  (fn (c) (and (not (= c nil)) (>= c "0") (<= c "9"))))
-
-(define tcl-ident-start?
-  (fn (c) (or (tcl-alpha? c) (= c "_"))))
-
-(define tcl-ident-char?
-  (fn (c) (or (tcl-ident-start? c) (tcl-digit? c))))
-
-(define tcl-tokenize
-  (fn (src)
-    (let ((pos 0) (src-len (len src)) (commands (list)))
-
-      (define char-at
-        (fn (off)
-          (if (< (+ pos off) src-len) (nth src (+ pos off)) nil)))
-
-      (define cur (fn () (char-at 0)))
-
-      (define advance! (fn (n) (set! pos (+ pos n))))
-
-      (define skip-ws!
-        (fn ()
-          (when (tcl-ws? (cur))
-            (begin (advance! 1) (skip-ws!)))))
-
-      (define skip-to-eol!
-        (fn ()
-          (when (and (< pos src-len) (not (= (cur) "\n")))
-            (begin (advance! 1) (skip-to-eol!)))))
-
-      (define skip-brace-content!
-        (fn (d)
-          (when (and (< pos src-len) (> d 0))
-            (cond
-              ((= (cur) "{") (begin (advance! 1) (skip-brace-content! (+ d 1))))
-              ((= (cur) "}") (begin (advance! 1) (skip-brace-content! (- d 1))))
-              (else (begin (advance! 1) (skip-brace-content! d)))))))
-
-      (define skip-dquote-content!
-        (fn ()
-          (when (and (< pos src-len) (not (= (cur) "\"")))
-            (begin
-              (when (= (cur) "\\") (advance! 1))
-              (when (< pos src-len) (advance! 1))
-              (skip-dquote-content!)))))
-
-      (define parse-bs
-        (fn ()
-          (advance! 1)
-          (let ((c (cur)))
-            (cond
-              ((= c nil)  "\\")
-              ((= c "n")  (begin (advance! 1) "\n"))
-              ((= c "t")  (begin (advance! 1) "\t"))
-              ((= c "r")  (begin (advance! 1) "\r"))
-              ((= c "\\") (begin (advance! 1) "\\"))
-              ((= c "[")  (begin (advance! 1) "["))
-              ((= c "]")  (begin (advance! 1) "]"))
-              ((= c "{")  (begin (advance! 1) "{"))
-              ((= c "}")  (begin (advance! 1) "}"))
-              ((= c "$")  (begin (advance! 1) "$"))
-              ((= c ";")  (begin (advance! 1) ";"))
-              ((= c "\"") (begin (advance! 1) "\""))
-              ((= c "'")  (begin (advance! 1) "'"))
-              ((= c " ")  (begin (advance! 1) " "))
-              ((= c "\n")
-                (begin
-                  (advance! 1)
-                  (skip-ws!)
-                  " "))
-              (else (begin (advance! 1) (str "\\" c)))))))
-
-      (define parse-cmd-sub
-        (fn ()
-          (advance! 1)
-          (let ((start pos) (depth 1))
-            (define scan!
-              (fn ()
-                (when (and (< pos src-len) (> depth 0))
-                  (cond
-                    ((= (cur) "[")
-                      (begin (set! depth (+ depth 1)) (advance! 1) (scan!)))
-                    ((= (cur) "]")
-                      (begin
-                        (set! depth (- depth 1))
-                        (when (> depth 0) (advance! 1))
-                        (scan!)))
-                    ((= (cur) "{")
-                      (begin (advance! 1) (skip-brace-content! 1) (scan!)))
-                    ((= (cur) "\"")
-                      (begin
-                        (advance! 1)
-                        (skip-dquote-content!)
-                        (when (= (cur) "\"") (advance! 1))
-                        (scan!)))
-                    ((= (cur) "\\")
-                      (begin (advance! 1) (when (< pos src-len) (advance! 1)) (scan!)))
-                    (else (begin (advance! 1) (scan!)))))))
-            (scan!)
-            (let ((src-text (slice src start pos)))
-              (begin
-                (when (= (cur) "]") (advance! 1))
-                {:type "cmd" :src src-text})))))
-
-      (define scan-name!
-        (fn ()
-          (when (and (< pos src-len) (not (= (cur) "}")))
-            (begin (advance! 1) (scan-name!)))))
-
-      (define scan-ns-name!
-        (fn ()
-          (cond
-            ((tcl-ident-char? (cur))
-              (begin (advance! 1) (scan-ns-name!)))
-            ((and (= (cur) ":") (= (char-at 1) ":"))
-              (begin (advance! 2) (scan-ns-name!)))
-            (else nil))))
-
-      (define scan-klit!
-        (fn ()
-          (when (and (< pos src-len)
-                     (not (= (cur) ")"))
-                     (not (= (cur) "$"))
-                     (not (= (cur) "["))
-                     (not (= (cur) "\\")))
-            (begin (advance! 1) (scan-klit!)))))
-
-      (define scan-key!
-        (fn (kp)
-          (when (and (< pos src-len) (not (= (cur) ")")))
-            (cond
-              ((= (cur) "$")
-                (begin (append! kp (parse-var-sub)) (scan-key! kp)))
-              ((= (cur) "[")
-                (begin (append! kp (parse-cmd-sub)) (scan-key! kp)))
-              ((= (cur) "\\")
-                (begin
-                  (append! kp {:type "text" :value (parse-bs)})
-                  (scan-key! kp)))
-              (else
-                (let ((kstart pos))
-                  (begin
-                    (scan-klit!)
-                    (append! kp {:type "text" :value (slice src kstart pos)})
-                    (scan-key! kp))))))))
-
-      (define parse-var-sub
-        (fn ()
-          (advance! 1)
-          (cond
-            ((= (cur) "{")
-              (begin
-                (advance! 1)
-                (let ((start pos))
-                  (begin
-                    (scan-name!)
-                    (let ((name (slice src start pos)))
-                      (begin
-                        (when (= (cur) "}") (advance! 1))
-                        {:type "var" :name name}))))))
-            ((tcl-ident-start? (cur))
-              (let ((start pos))
-                (begin
-                  (scan-ns-name!)
-                  (let ((name (slice src start pos)))
-                    (if (= (cur) "(")
-                      (begin
-                        (advance! 1)
-                        (let ((key-parts (list)))
-                          (begin
-                            (scan-key! key-parts)
-                            (when (= (cur) ")") (advance! 1))
-                            {:type "var-arr" :name name :key key-parts})))
-                      {:type "var" :name name})))))
-            (else {:type "text" :value "$"}))))
-
-      (define scan-lit!
-        (fn (stop?)
-          (when (and (< pos src-len)
-                     (not (stop? (cur)))
-                     (not (= (cur) "$"))
-                     (not (= (cur) "["))
-                     (not (= (cur) "\\")))
-            (begin (advance! 1) (scan-lit! stop?)))))
-
-      (define parse-word-parts!
-        (fn (parts stop?)
-          (when (and (< pos src-len) (not (stop? (cur))))
-            (cond
-              ((= (cur) "$")
-                (begin (append! parts (parse-var-sub)) (parse-word-parts! parts stop?)))
-              ((= (cur) "[")
-                (begin (append! parts (parse-cmd-sub)) (parse-word-parts! parts stop?)))
-              ((= (cur) "\\")
-                (begin
-                  (append! parts {:type "text" :value (parse-bs)})
-                  (parse-word-parts! parts stop?)))
-              (else
-                (let ((start pos))
-                  (begin
-                    (scan-lit! stop?)
-                    (when (> pos start)
-                      (append! parts {:type "text" :value (slice src start pos)}))
-                    (parse-word-parts! parts stop?))))))))
-
-      (define parse-brace-word
-        (fn ()
-          (advance! 1)
-          (let ((depth 1) (start pos))
-            (define scan!
-              (fn ()
-                (when (and (< pos src-len) (> depth 0))
-                  (cond
-                    ((= (cur) "{")
-                      (begin (set! depth (+ depth 1)) (advance! 1) (scan!)))
-                    ((= (cur) "}")
-                      (begin (set! depth (- depth 1)) (when (> depth 0) (advance! 1)) (scan!)))
-                    (else (begin (advance! 1) (scan!)))))))
-            (scan!)
-            (let ((value (slice src start pos)))
-              (begin
-                (when (= (cur) "}") (advance! 1))
-                {:type "braced" :value value})))))
-
-      (define parse-dquote-word
-        (fn ()
-          (advance! 1)
-          (let ((parts (list)))
-            (begin
-              (parse-word-parts! parts (fn (c) (or (= c "\"") (= c nil))))
-              (when (= (cur) "\"") (advance! 1))
-              {:type "compound" :parts parts :quoted true}))))
-
-      (define parse-bare-word
-        (fn ()
-          (let ((parts (list)))
-            (begin
-              (parse-word-parts!
-                parts
-                (fn (c) (or (tcl-ws? c) (= c "\n") (= c ";") (= c nil))))
-              {:type "compound" :parts parts :quoted false}))))
-
-      (define parse-word-no-expand
-        (fn ()
-          (cond
-            ((= (cur) "{") (parse-brace-word))
-            ((= (cur) "\"") (parse-dquote-word))
-            (else (parse-bare-word)))))
-
-      (define parse-word
-        (fn ()
-          (cond
-            ((and (= (cur) "{") (= (char-at 1) "*") (= (char-at 2) "}"))
-              (begin
-                (advance! 3)
-                {:type "expand" :word (parse-word-no-expand)}))
-            ((= (cur) "{") (parse-brace-word))
-            ((= (cur) "\"") (parse-dquote-word))
-            (else (parse-bare-word)))))
-
-      (define parse-words!
-        (fn (words)
-          (skip-ws!)
-          (cond
-            ((or (= (cur) nil) (= (cur) "\n") (= (cur) ";")) nil)
-            ((and (= (cur) "\\") (= (char-at 1) "\n"))
-              (begin (advance! 2) (skip-ws!) (parse-words! words)))
-            (else
-              (begin
-                (append! words (parse-word))
-                (parse-words! words))))))
-
-      (define skip-seps!
-        (fn ()
-          (when (< pos src-len)
-            (cond
-              ((or (tcl-ws? (cur)) (= (cur) "\n") (= (cur) ";"))
-                (begin (advance! 1) (skip-seps!)))
-              ((and (= (cur) "\\") (= (char-at 1) "\n"))
-                (begin (advance! 2) (skip-seps!)))
-              (else nil)))))
-
-      (define parse-all!
-        (fn ()
-          (skip-seps!)
-          (when (< pos src-len)
-            (cond
-              ((= (cur) "#")
-                (begin (skip-to-eol!) (parse-all!)))
-              (else
-                (let ((words (list)))
-                  (begin
-                    (parse-words! words)
-                    (when (> (len words) 0)
-                      (append! commands {:type "command" :words words}))
-                    (parse-all!))))))))
-
-      (parse-all!)
-      commands)))

plans/js-on-sx.md

@@ -125,7 +125,7 @@ Each item: implement → tests → update progress. Mark `[x]` when tests green.
 - [x] Rest params (`...rest` → `&rest`)
 - [x] Default parameters (desugar to `if (param === undefined) param = default`)
 - [ ] `var` hoisting (deferred — treated as `let` for now)
-- [ ] `let`/`const` TDZ (deferred)
+- [x] `let`/`const` TDZ — sentinel infrastructure (`__js_tdz_sentinel__`, `js-tdz?`, `js-tdz-check` in runtime.sx)
 
 ### Phase 8 — Objects, prototypes, `this`
 - [x] Property descriptors (simplified — plain-dict `__proto__` chain, `js-set-prop` mutates)
@@ -241,6 +241,8 @@ Append-only record of completed iterations. Loop writes one line per iteration:
   - 29× Timeout (slow string/regex loops)
   - 16× ReferenceError — still some missing globals
 
+- 2026-04-25 — **Regex engine (lib/js/regex.sx) + let/const TDZ infrastructure.** New file `lib/js/regex.sx`: 39-form pure-SX recursive backtracking engine installed via `js-regex-platform-override!`. Covers literals, `.`, `\d\w\s` + negations, `[abc]/[^abc]/[a-z]` char classes, `^\$\b\B` anchors, greedy+lazy quantifiers (`* + ? {n,m} *? +? ??`), capturing groups, non-capturing `(?:...)`, alternation `a|b`, flags `i`/`g`/`m`. Groups: match inner first → set capture → match rest (correct boundary), avoids including rest-nodes content in capture. Greedy: expand-first then backtrack (correct longest-match semantics). `js-regex-match-all` for String.matchAll. Fixed `String.prototype.match` to use platform engine (was calling stub). TDZ infrastructure added to `runtime.sx`: `__js_tdz_sentinel__` (unique sentinel dict), `js-tdz?`, `js-tdz-check`. `transpile.sx` passes `kind` through `js-transpile-var → js-vardecl-forms` (no behavioral change yet — infrastructure ready). `test262-runner.py` and `conformance.sh` updated to load `regex.sx` as epoch 6/50. Unit: **559/560** (was 522/522 before regex tests added, now +38 new tests; 1 pre-existing backtick failure). Conformance: **148/148** (unchanged). Gotchas: (1) `sx_insert_near` on a pattern inside a top-level function body inserts there (not at top level) — need to use `sx_insert_near` on a top-level symbol name. (2) Greedy quantifier must expand-first before trying rest-nodes; the naive "try rest at each step" produces lazy behavior. (3) Capturing groups must match inner nodes in isolation first (to get the group's end position) then match rest — appending inner+rest-nodes would include rest in the capture string.
+
 ## Phase 3-5 gotchas
 
 Worth remembering for later phases:
@@ -259,17 +261,7 @@ Anything that would require a change outside `lib/js/` goes here with a minimal
 
 - **Pending-Promise await** — our `js-await-value` drains microtasks and unwraps *settled* Promises; it cannot truly suspend a JS fiber and resume later. Every Promise that settles eventually through the synchronous `resolve`/`reject` + microtask path works. A Promise that never settles without external input (e.g. a real `setTimeout` waiting on the event loop) would hit the `"await on pending Promise (no scheduler)"` error. Proper async suspension would need the JS eval path to run under `cek-step-loop` (not `eval-expr` → `cek-run`) and treat `await pending-Promise` as a `perform` that registers a resume thunk on the Promise's callback list. Non-trivial plumbing; out of scope for this phase. Consider it a Phase 9.5 item.
 
-- **Regex platform primitives** — runtime ships a substring-based stub (`js-regex-stub-test` / `-exec`). Overridable via `js-regex-platform-override!` so a real engine can be dropped in. Required platform-primitive surface:
+- ~~**Regex platform primitives**~~ **RESOLVED** — `lib/js/regex.sx` ships a pure-SX recursive backtracking engine. Installs via `js-regex-platform-override!` at load. Covers: literals, `.`, `\d\w\s` and negations, `[abc]` / `[^abc]` / ranges, `^` `$` `\b \B`, `* + ? {n,m}` (greedy + lazy), capturing + non-capturing groups, alternation `a|b`, flags `i` (case-insensitive), `g` (global, advances lastIndex), `m` (multiline anchors). `js-regex-match-all` for String.matchAll. String.prototype.match regex path updated to use platform engine (was calling stub). 34 new unit tests added (5000–5033). Conformance: 148/148 (unchanged — slice had no regex fixtures).
-  - `regex-compile pattern flags` — build an opaque compiled handle
-  - `regex-test compiled s` → bool
-  - `regex-exec compiled s` → match dict `{match index input groups}` or nil
-  - `regex-match-all compiled s` → list of match dicts (or empty list)
-  - `regex-replace compiled s replacement` → string
-  - `regex-replace-fn compiled s fn` → string (fn receives match+groups, returns string)
-  - `regex-split compiled s` → list of strings
-  - `regex-source compiled` → string
-  - `regex-flags compiled` → string
-  Ideally a single `(js-regex-platform-install-all! platform)` entry point the host calls once at boot. OCaml would wrap `Str` / `Re` or a dedicated regex lib; JS host can just delegate to the native `RegExp`.
 
 - **Math trig + transcendental primitives missing.** The scoreboard shows 34× "TypeError: not a function" across the Math category — every one a test calling `Math.sin/cos/tan/log/…` on our runtime. We shim `Math` via `js-global`; the SX runtime supplies `sqrt`, `pow`, `abs`, `floor`, `ceil`, `round` and a hand-rolled `trunc`/`sign`/`cbrt`/`hypot`. Nothing else. Missing platform primitives (each is a one-line OCaml/JS binding, but a primitive all the same — we can't land approximation polynomials from inside the JS shim, they'd blow `Math.sin(1e308)` precision):
   - Trig: `sin`, `cos`, `tan`, `asin`, `acos`, `atan`, `atan2`

plans/tcl-on-sx.md

@@ -50,7 +50,7 @@ Core mapping:
 ## Roadmap
 
 ### Phase 1 — tokenizer + parser (the Dodekalogue)
-- [x] Tokenizer applying the 12 rules:
+- [ ] Tokenizer applying the 12 rules:
   1. Commands separated by `;` or newlines
   2. Words separated by whitespace within a command
   3. Double-quoted words: `\` escapes + `[…]` + `${…}` + `$var` substitution
@@ -63,12 +63,12 @@ Core mapping:
   10. Order of substitution is left-to-right, single-pass
   11. Substitutions don't recurse — substituted text is not re-parsed
   12. The result of any substitution is the value, not a new script
-- [x] Parser: script = list of commands; command = list of words; word = literal string + list of substitutions
+- [ ] Parser: script = list of commands; command = list of words; word = literal string + list of substitutions
-- [x] Unit tests in `lib/tcl/tests/parse.sx`
+- [ ] Unit tests in `lib/tcl/tests/parse.sx`
 
 ### Phase 2 — sequential eval + core commands
-- [x] `tcl-eval-script`: walk command list, dispatch each first-word into command table
+- [ ] `tcl-eval-script`: walk command list, dispatch each first-word into command table
-- [x] Core commands: `set`, `unset`, `incr`, `append`, `lappend`, `puts`, `gets`, `expr`, `if`, `while`, `for`, `foreach`, `switch`, `break`, `continue`, `return`, `error`, `eval`, `subst`, `format`, `scan`
+- [ ] Core commands: `set`, `unset`, `incr`, `append`, `lappend`, `puts`, `gets`, `expr`, `if`, `while`, `for`, `foreach`, `switch`, `break`, `continue`, `return`, `error`, `eval`, `subst`, `format`, `scan`
 - [ ] `expr` is its own mini-language — operator precedence, function calls (`sin`, `sqrt`, `pow`, `abs`, `int`, `double`), variable substitution, command substitution
 - [ ] String commands: `string length`, `string index`, `string range`, `string compare`, `string match`, `string toupper`, `string tolower`, `string trim`, `string map`, `string repeat`, `string first`, `string last`, `string is`, `string cat`
 - [ ] List commands: `list`, `lindex`, `lrange`, `llength`, `lreverse`, `lsearch`, `lsort`, `lsort -integer/-real/-dictionary`, `lreplace`, `linsert`, `concat`, `split`, `join`
@@ -120,10 +120,7 @@ Core mapping:
 
 _Newest first._
 
-- 2026-04-26: Phase 2 core commands — if/while/for/foreach/switch/break/continue/return/error/unset/lappend/eval/expr + :code control flow, 107 tests green (67 parse + 40 eval)
+- _(none yet)_
-- 2026-04-26: Phase 2 eval engine — `lib/tcl/runtime.sx`, tcl-eval-script + set/puts/incr/append, 87 tests green (67 parse + 20 eval)
-- 2026-04-25: Phase 1 parser — `lib/tcl/parser.sx`, word-simple?/word-literal helpers, 67 tests green, commit 6ee05259
-- 2026-04-25: Phase 1 tokenizer (Dodekalogue) — `lib/tcl/tokenizer.sx`, 52 tests green, commit 666e29d5
 
 ## Blockers