merge: architecture → loops/tcl — R7RS, JIT, env-as-value

Resolved conflicts in hosts/ocaml/lib/sx_primitives.ml:
- Took architecture's make-regexp/regexp-* primitives (Tcl runtime depends on them)
- Took architecture's Integer typing for clock-seconds/milliseconds/format
- Kept Phase 4 env-lookup/env-extend additions

Tcl: 342/342 tests passing.

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

hosts/ocaml/bin/sx_server.ml

@@ -703,6 +703,11 @@ let setup_evaluator_bridge env =
     | [expr; e] -> Sx_ref.eval_expr expr (Env (Sx_runtime.unwrap_env e))
     | [expr] -> Sx_ref.eval_expr expr (Env env)
     | _ -> raise (Eval_error "eval-expr: expected (expr env?)"));
+  (* eval-in-env: (env expr) → result.  Evaluates expr in the given env. *)
+  Sx_primitives.register "eval-in-env" (fun args ->
+    match args with
+    | [e; expr] -> Sx_ref.eval_expr expr e
+    | _ -> raise (Eval_error "eval-in-env: (env expr)"));
   bind "trampoline" (fun args ->
     match args with
     | [v] ->
@@ -764,7 +769,13 @@ let setup_evaluator_bridge env =
     | _ -> raise (Eval_error "register-special-form!: expected (name handler)"));
   ignore (env_bind env "*custom-special-forms*" Sx_ref.custom_special_forms);
   ignore (Sx_ref.register_special_form (String "<>") (NativeFn ("<>", fun args ->
-    List (List.map (fun a -> Sx_ref.eval_expr a (Env env)) args))))
+    List (List.map (fun a -> Sx_ref.eval_expr a (Env env)) args))));
+  (* current-env: special form — returns current lexical env as a first-class value *)
+  ignore (Sx_ref.register_special_form (String "current-env")
+    (NativeFn ("current-env", fun args ->
+      match args with
+      | [_arg_list; env_val] -> env_val
+      | _ -> Nil)))
 
 (* ---- Type predicates and introspection ---- *)
 let setup_introspection env =
@@ -950,7 +961,24 @@ let setup_env_operations env =
   bind "env-has?" (fun args -> match args with [e; String k] -> Bool (Sx_types.env_has (uw e) k) | [e; Keyword k] -> Bool (Sx_types.env_has (uw e) k) | _ -> raise (Eval_error "env-has?: expected env and string"));
   bind "env-bind!" (fun args -> match args with [e; String k; v] -> Sx_types.env_bind (uw e) k v | [e; Keyword k; v] -> Sx_types.env_bind (uw e) k v | _ -> raise (Eval_error "env-bind!: expected env, key, value"));
   bind "env-set!" (fun args -> match args with [e; String k; v] -> Sx_types.env_set (uw e) k v | [e; Keyword k; v] -> Sx_types.env_set (uw e) k v | _ -> raise (Eval_error "env-set!: expected env, key, value"));
-  bind "env-extend" (fun args -> match args with [e] -> Env (Sx_types.env_extend (uw e)) | _ -> raise (Eval_error "env-extend: expected env"));
+  bind "env-extend" (fun args ->
+    match args with
+    | e :: pairs ->
+      let child = Sx_types.env_extend (uw e) in
+      let rec go = function
+        | [] -> ()
+        | k :: v :: rest ->
+          ignore (Sx_types.env_bind child (Sx_runtime.value_to_str k) v); go rest
+        | [_] -> raise (Eval_error "env-extend: odd number of key-val pairs") in
+      go pairs; Env child
+    | _ -> raise (Eval_error "env-extend: expected env"));
+  bind "env-lookup" (fun args ->
+    match args with
+    | [e; key] ->
+      let k = Sx_runtime.value_to_str key in
+      let raw = uw e in
+      if Sx_types.env_has raw k then Sx_types.env_get raw k else Nil
+    | _ -> raise (Eval_error "env-lookup: (env key)"));
   bind "env-merge" (fun args -> match args with [a; b] -> Sx_runtime.env_merge a b | _ -> raise (Eval_error "env-merge: expected 2 envs"))
 
 (* ---- Strict mode (gradual type system support) ---- *)

hosts/ocaml/lib/sx_primitives.ml

@@ -3138,4 +3138,36 @@ let () =
         end
       done;
       String (Buffer.contents buf)
-    | _ -> raise (Eval_error "clock-format: (seconds [format])"))
+    | _ -> raise (Eval_error "clock-format: (seconds [format])"));
+
+  (* === Env-as-value (Phase 4) === *)
+
+  (* env-lookup: (env key) → value or nil.  Works on Env, Dict, or Nil. *)
+  register "env-lookup" (fun args ->
+    let unwrap = function
+      | Env e -> e
+      | Nil -> make_env ()
+      | _ -> raise (Eval_error "env-lookup: first arg must be an environment") in
+    match args with
+    | [env_val; key] ->
+      let e = unwrap env_val in
+      let k = value_to_string key in
+      if env_has e k then env_get e k else Nil
+    | _ -> raise (Eval_error "env-lookup: (env key)"));
+
+  (* env-extend: (env [key val ...]) → new child env with optional bindings. *)
+  register "env-extend" (fun args ->
+    match args with
+    | [] -> raise (Eval_error "env-extend: requires at least one arg")
+    | env_val :: pairs ->
+      let parent_env = match env_val with
+        | Env e -> e
+        | Nil -> make_env ()
+        | _ -> raise (Eval_error "env-extend: first arg must be an environment") in
+      let child = env_extend parent_env in
+      let rec add_bindings = function
+        | [] -> ()
+        | k :: v :: rest -> ignore (env_bind child (value_to_string k) v); add_bindings rest
+        | [_] -> raise (Eval_error "env-extend: odd number of key-val pairs") in
+      add_bindings pairs;
+      Env child)

hosts/ocaml/lib/sx_runtime.ml

@@ -539,3 +539,4 @@ let jit_try_call f args =
       (match hook f arg_list with Some result -> incr _jit_hit; result | None -> incr _jit_miss; _jit_skip_sentinel)
     | _ -> incr _jit_skip; _jit_skip_sentinel
 
+

lib/fiber.sx

@@ -0,0 +1,44 @@
+; lib/fiber.sx — pure SX fiber library using call/cc
+;
+; A fiber is a cooperative coroutine with true suspension (no eager
+; pre-execution). Each fiber is a dict {:resume fn :done? fn}.
+;
+; make-fiber body   → fiber dict
+;   body = (fn (yield init-val) ...)  — body receives yield + first resume val
+;   yield = (fn (val) ...)            — suspends fiber, returns val to resumer
+;
+; fiber-resume f v  → next yielded value, or nil when body returns
+; fiber-done? f     → true after body has returned
+
+(define make-fiber
+  (fn (body)
+    (let
+      ((resume-k nil)
+        (caller-k nil)
+        (done false))
+      (let
+        ((yield
+            (fn (val)
+              (call/cc
+                (fn (k)
+                  (set! resume-k k)
+                  (caller-k val))))))
+        {:resume
+         (fn (val)
+           (if
+             done
+             nil
+             (call/cc
+               (fn (k)
+                 (set! caller-k k)
+                 (if
+                   (nil? resume-k)
+                   (begin
+                     (body yield val)
+                     (set! done true)
+                     (k nil))
+                   (resume-k val))))))
+         :done? (fn () done)}))))
+
+(define fiber-resume (fn (f v) ((get f :resume) v)))
+(define fiber-done?  (fn (f) ((get f :done?))))

lib/tcl/test.sh

@@ -39,6 +39,7 @@ cat > "$TMPFILE" << EPOCHS
 (epoch 3)
 (load "lib/tcl/tests/parse.sx")
 (epoch 4)
+(load "lib/fiber.sx")
 (load "lib/tcl/runtime.sx")
 (epoch 5)
 (load "lib/tcl/tests/eval.sx")

lib/tcl/tests/coro.sx

@@ -95,15 +95,15 @@
       (get (run "proc g {} { yield }\ncoroutine cg g\ncg") :result)
       "")
 
-    ; --- clock seconds stub ---
+    ; --- clock seconds ---
     (ok "clock-seconds"
-      (get (run "clock seconds") :result)
+      (> (parse-int (get (run "clock seconds") :result)) 0)
-      "0")
+      true)
 
-    ; --- clock milliseconds stub ---
+    ; --- clock milliseconds ---
     (ok "clock-milliseconds"
-      (get (run "clock milliseconds") :result)
+      (> (parse-int (get (run "clock milliseconds") :result)) 0)
-      "0")
+      true)
 
     ; --- clock format stub ---
     (ok "clock-format"

lib/tcl/tests/eval.sx

@@ -329,6 +329,54 @@
         (run "proc with-temp-var {varname tempval body} {\n    upvar 1 $varname v\n    set saved $v\n    set v $tempval\n    uplevel 1 $body\n    set v $saved\n}\nset x 100\nwith-temp-var x 999 {\n    set captured $x\n}\nlist $x $captured")
         :result)
       "100 999")
+    (ok
+      "array-set-get"
+      (get
+        (run "array set a {x 1 y 2 z 3}; array get a x")
+        :result)
+      "x 1")
+    (ok
+      "array-names"
+      (get
+        (run "array set a {p 10 q 20}; lsort [array names a]")
+        :result)
+      "p q")
+    (ok
+      "array-size"
+      (get
+        (run "array set a {x 1 y 2 z 3}; array size a")
+        :result)
+      "3")
+    (ok
+      "array-exists-true"
+      (get
+        (run "array set a {x 1}; array exists a")
+        :result)
+      "1")
+    (ok
+      "array-exists-false"
+      (get
+        (run "array exists nosucharray")
+        :result)
+      "0")
+    (ok
+      "array-unset-key"
+      (get
+        (run "array set a {x 1 y 2 z 3}; array unset a y; lsort [array names a]")
+        :result)
+      "x z")
+    (ok
+      "array-scalar-access"
+      (get
+        (run "set a(foo) hello; set a(bar) world; set a(foo)")
+        :result)
+      "hello")
+    (ok
+      "array-get-all"
+      (get
+        (run "set a(k) v; set pairs [array get a]; llength $pairs")
+        :result)
+      "2")
     (dict
       "passed"
       tcl-eval-pass

lib/tcl/tests/idioms.sx

@@ -29,161 +29,164 @@
     (define
       ok
       (fn (label actual expected) (tcl-idiom-assert label expected actual)))
-
+    (ok
-    ; 1. lmap idiom: accumulate mapped values with foreach+lappend
+      "idiom-lmap"
-    (ok "idiom-lmap"
       (get
-        (run "set result {}\nforeach x {1 2 3} { lappend result [expr {$x * $x}] }\nset result")
+        (run
+          "set result {}\nforeach x {1 2 3} { lappend result [expr {$x * $x}] }\nset result")
         :result)
       "1 4 9")
-
+    (ok
-    ; 2. Recursive list flatten
+      "idiom-flatten"
-    (ok "idiom-flatten"
       (get
         (run
           "proc flatten {lst} { set out {}\n  foreach item $lst {\n    if {[llength $item] > 1} {\n      foreach sub [flatten $item] { lappend out $sub }\n    } else {\n      lappend out $item\n    }\n  }\n  return $out\n}\nflatten {1 {2 3} {4 {5 6}}}")
         :result)
       "1 2 3 4 5 6")
-
+    (ok
-    ; 3. String builder accumulator
+      "idiom-string-builder"
-    (ok "idiom-string-builder"
       (get
-        (run "set buf \"\"\nforeach w {Hello World Tcl} { append buf $w \" \" }\nstring trimright $buf")
+        (run
+          "set buf \"\"\nforeach w {Hello World Tcl} { append buf $w \" \" }\nstring trimright $buf")
         :result)
       "Hello World Tcl")
-
+    (ok
-    ; 4. Default parameter via info exists
+      "idiom-default-param"
-    (ok "idiom-default-param"
+      (get (run "if {![info exists x]} { set x 42 }\nset x") :result)
-      (get
-        (run "if {![info exists x]} { set x 42 }\nset x")
-        :result)
       "42")
-
+    (ok
-    ; 5. Association list lookup (parallel key/value lists)
+      "idiom-alist-lookup"
-    (ok "idiom-alist-lookup"
       (get
         (run
           "set keys {a b c}\nset vals {10 20 30}\nset idx [lsearch $keys b]\nlindex $vals $idx")
         :result)
       "20")
-
+    (ok
-    ; 6. Proc with optional args via args
+      "idiom-optional-args"
-    (ok "idiom-optional-args"
       (get
         (run
           "proc greet {name args} {\n  set greeting \"Hello\"\n  if {[llength $args] > 0} { set greeting [lindex $args 0] }\n  return \"$greeting $name\"\n}\ngreet World Hi")
         :result)
       "Hi World")
-
+    (ok
-    ; 7. Builder pattern: dict create from args
+      "idiom-dict-builder"
-    (ok "idiom-dict-builder"
       (get
         (run
           "proc build-dict {args} { dict create {*}$args }\ndict get [build-dict name Alice age 30] name")
         :result)
       "Alice")
-
+    (ok
-    ; 8. Loop with index using array
+      "idiom-loop-with-index"
-    (ok "idiom-loop-with-index"
       (get
-        (run
+        (run "set i 0\nforeach x {a b c} { set arr($i) $x; incr i }\nset arr(1)")
-          "set i 0\nforeach x {a b c} { set arr($i) $x; incr i }\nset arr(1)")
         :result)
       "b")
-
+    (ok
-    ; 9. String reverse via split+lreverse+join
+      "idiom-string-reverse"
-    (ok "idiom-string-reverse"
       (get
         (run
           "set s hello\nset chars [split $s \"\"]\nset rev [lreverse $chars]\njoin $rev \"\"")
         :result)
       "olleh")
-
+    (ok "idiom-number-format" (get (run "format \"%05d\" 42") :result) "00042")
-    ; 10. Number to padded string
+    (ok
-    (ok "idiom-number-format"
+      "idiom-dict-comprehension"
-      (get (run "format \"%05d\" 42") :result)
-      "00042")
-
-    ; 11. Dict comprehension pattern
-    (ok "idiom-dict-comprehension"
       (get
         (run
           "set squares {}\nforeach n {1 2 3 4} { dict set squares $n [expr {$n * $n}] }\ndict get $squares 3")
         :result)
       "9")
-
+    (ok
-    ; 12. Stack ADT using list: push/pop
+      "idiom-stack"
-    (ok "idiom-stack"
       (get
         (run
           "proc stack-push {stackvar val} { upvar $stackvar s; lappend s $val }\nproc stack-pop {stackvar} { upvar $stackvar s; set val [lindex $s end]; set s [lrange $s 0 end-1]; return $val }\nset stk {}\nstack-push stk 10\nstack-push stk 20\nstack-push stk 30\nstack-pop stk")
         :result)
       "30")
-
+    (ok
-    ; 13. Queue ADT using list: enqueue/dequeue
+      "idiom-queue"
-    (ok "idiom-queue"
       (get
         (run
           "proc q-enq {qvar val} { upvar $qvar q; lappend q $val }\nproc q-deq {qvar} { upvar $qvar q; set val [lindex $q 0]; set q [lrange $q 1 end]; return $val }\nset q {}\nq-enq q alpha\nq-enq q beta\nq-enq q gamma\nq-deq q")
         :result)
       "alpha")
-
+    (ok
-    ; 14. Pipeline via proc chaining
+      "idiom-pipeline"
-    (ok "idiom-pipeline"
       (get
         (run
           "proc double {x} { expr {$x * 2} }\nproc add1 {x} { expr {$x + 1} }\nproc pipeline {val procs} { foreach p $procs { set val [$p $val] }; return $val }\npipeline 5 {double add1 double}")
         :result)
       "22")
-
+    (ok
-    ; 15. Memoize pattern using dict (simple cache, not recursive)
+      "idiom-memoize"
-    (ok "idiom-memoize"
       (get
         (run
           "set cache {}\nproc cached-square {n} { global cache\n  if {[dict exists $cache $n]} { return [dict get $cache $n] }\n  set r [expr {$n * $n}]\n  dict set cache $n $r\n  return $r\n}\nset a [cached-square 7]\nset b [cached-square 7]\nset c [cached-square 8]\nexpr {$a == $b && $c == 64}")
         :result)
       "1")
-
+    (ok
-    ; 16. Simple expression evaluator in Tcl (recursive descent)
+      "idiom-recursive-eval"
-    (ok "idiom-recursive-eval"
       (get
         (run
           "proc calc {expr} { return [::tcl::mathop::+ 0 [expr $expr]] }\nexpr {3 + 4 * 2}")
         :result)
       "11")
-
+    (ok
-    ; 17. Apply proc to each pair in a dict
+      "idiom-dict-for"
-    (ok "idiom-dict-for"
       (get
         (run
           "set d [dict create a 1 b 2 c 3]\nset total 0\ndict for {k v} $d { incr total $v }\nset total")
         :result)
       "6")
-
+    (ok
-    ; 18. Find max in list
+      "idiom-find-max"
-    (ok "idiom-find-max"
       (get
         (run
           "proc list-max {lst} {\n  set m [lindex $lst 0]\n  foreach x $lst { if {$x > $m} { set m $x } }\n  return $m\n}\nlist-max {3 1 4 1 5 9 2 6}")
         :result)
       "9")
-
+    (ok
-    ; 19. Filter list by predicate
+      "idiom-filter-list"
-    (ok "idiom-filter-list"
       (get
         (run
           "proc list-filter {lst pred} {\n  set out {}\n  foreach x $lst { if {[$pred $x]} { lappend out $x } }\n  return $out\n}\nproc is-even {n} { expr {$n % 2 == 0} }\nlist-filter {1 2 3 4 5 6} is-even")
         :result)
       "2 4 6")
-
+    (ok
-    ; 20. Zip two lists
+      "idiom-zip"
-    (ok "idiom-zip"
       (get
         (run
           "proc zip {a b} {\n  set out {}\n  set n [llength $a]\n  for {set i 0} {$i < $n} {incr i} {\n    lappend out [lindex $a $i]\n    lappend out [lindex $b $i]\n  }\n  return $out\n}\nzip {1 2 3} {a b c}")
         :result)
       "1 a 2 b 3 c")
-
+    (ok
+      "env-lookup-basic"
+      (env-lookup (let ((x 42)) (current-env)) "x")
+      42)
+    (ok
+      "env-lookup-missing"
+      (env-lookup (let ((x 42)) (current-env)) "z")
+      nil)
+    (ok
+      "env-extend-lookup"
+      (let
+        ((e (let ((x 5)) (current-env))))
+        (env-lookup (env-extend e "y" 10) "y"))
+      10)
+    (ok
+      "eval-in-env-parent"
+      (let
+        ((x 5))
+        (eval-in-env (env-extend (current-env) "y" 10) (quote (+ x y))))
+      15)
+    (ok
+      "eval-in-env-multi"
+      (let
+        ((base (current-env)))
+        (eval-in-env
+          (env-extend (env-extend base "a" 3) "b" 7)
+          (quote (* a b))))
+      21)
     (dict
       "passed"
       tcl-idiom-pass

plans/agent-briefings/sx-improvements-loop.md

@@ -0,0 +1,86 @@
+# sx-improvements loop agent
+
+Iterates `plans/sx-improvements.md` forever. One step per commit.
+
+```
+description: sx-improvements loop
+subagent_type: general-purpose
+run_in_background: true
+isolation: worktree
+```
+
+## Prompt
+
+You are the sole background agent iterating `plans/sx-improvements.md` on the `architecture` branch of `/root/rose-ash`. One step per commit, forever. Never push.
+
+## Restart baseline — check before each iteration
+
+1. Read `plans/sx-improvements.md` — find the first unchecked `[ ]` step in the progress log.
+2. Read the step's section in the plan for exact implementation details.
+3. Run the verification command for that step to confirm it currently fails.
+4. Implement. Verify. Commit. Tick the `[ ]` → `[x]` in the progress log. Next.
+
+## Test commands
+
+- **OCaml spec:** `sx_build target="ocaml"` then check `bin/run_tests.exe` output.
+- **JS spec (no DOM):** `node hosts/javascript/run_tests.js 2>&1 | tail -3`
+- **HyperScript kernel:** `node tests/hs-kernel-eval.js 2>&1 | tail -3`
+- **Baseline SX tests (non-HS):** `node hosts/javascript/run_tests.js 2>&1 | grep -v "hs-upstream\|hs-compat\|hs-dev" | grep "Results:"`
+
+Do NOT regress the pre-merge passing tests. After each step, confirm the count did not drop.
+
+## Ground rules (hard)
+
+- **Branch:** `architecture`. Never push. Never touch `main`.
+- **SX files:** `sx-tree` MCP tools ONLY (`sx_summarise`, `sx_read_subtree`, `sx_replace_node`, `sx_insert_child`, `sx_validate`). Read before edit. Validate after edit.
+- **Generated files:** NEVER edit `shared/static/wasm/sx/` or `shared/static/scripts/sx-*.js` directly. Rebuild via `sx_build`.
+- **HS mirror rule:** after editing any `lib/hyperscript/<f>.sx`, copy to `shared/static/wasm/sx/hs-<f>.sx` using `sx_write_file` with the same content.
+- **OCaml build:** `sx_build target="ocaml"` — never raw `dune exec`.
+- **JS build:** `sx_build target="js"`.
+- **One step per commit.** Tick the plan. Factual commit message.
+- **No new planning docs.** No comments in SX unless non-obvious.
+- **Unicode in SX:** raw UTF-8 only, never `\uXXXX` escapes.
+
+## Step-specific notes
+
+### Step 1 (JIT combinator bug)
+The bug is in `hosts/ocaml/lib/sx_vm.ml` — `call_closure_reuse` path strips locals when
+callee returns a closure. Look for the path where `call_closure_reuse` is invoked for a
+`VmClosure` return value. The fix is to not reuse frames when the call might return a
+closure, or to properly snapshot/restore `sp`. Check `spec/tests/test-parser-combinators.sx`
+for existing combinator tests; run `node tests/hs-kernel-eval.js` for the 11 failing HS tests.
+
+### Step 2 (letrec+resume)
+The bug is browser-only (`hosts/ocaml/browser/sx_browser.ml`). Write a minimal
+`spec/tests/test-letrec-resume.sx` that exercises `letrec` + `perform` + resume and
+verify it passes under `run_tests.exe` (OCaml server mode). Then check what
+`sx_browser.ml` does differently in the VmSuspension resume path.
+
+### Steps 3-4 (E38 source info)
+The API is already in `lib/hyperscript/runtime.sx`. The gap is in the tokenizer (no `:end`/`:line`)
+and some parser span completeness. Run the 4 sourceInfo tests to see exact failures:
+`node tests/hs-kernel-eval.js --suite sourceInfo` or grep results for `sourceInfo`.
+
+### Steps 5-8 (ADTs)
+Full spec in `plans/designs/sx-adt.md`. Implement in OCaml first (Step 5), then mirror
+to JS (Step 6). Steps 7-8 build on top. Write `spec/tests/test-adt.sx` from scratch —
+start with a `(define-type Maybe (Just value) (Nothing))` suite covering constructor,
+predicate, accessor, basic match, else clause.
+
+### Steps 9-11 (plugin system)
+Full spec in `plans/designs/hs-plugin-system.md`. The prolog hook migration (Step 11) is
+the most important for language-building — it's the pattern for all future embeds.
+
+### Steps 12-14 (performance)
+Profile first. Use `sx_harness_eval` to measure throughput on a tight loop before and
+after each change. Only commit if there's a measurable win (>10%).
+
+## General gotchas (all loops)
+
+- SX `do` is R7RS iteration. Use `begin` for multi-expr sequences.
+- `cond`/`when`/`let` bodies evaluate only the last expression.
+- `type-of` on a user-defined function returns `"lambda"`.
+- Shell heredoc `||` gets eaten — escape or use `case`.
+- `env-bind!` creates new bindings; `env-set!` mutates existing (walks scope chain).
+- After OCaml edits: the build takes ~2 min. Run `sx_build target="ocaml"` and wait.
+- After JS edits: retranspile with `sx_build target="js"` then re-run tests.

plans/sx-improvements.md

@@ -0,0 +1,210 @@
+# SX Language Improvements — roadmap
+
+Language-building improvements to the SX evaluator, compiler, and standard library.
+Ordered by impact and prerequisite chain. Each step is one loop commit.
+
+Branch: `architecture`. SX files via `sx-tree` MCP only. Never edit generated files.
+
+## Current baseline (2026-05-06)
+
+- SX core spec: 2571 passing (595 non-HS pre-existing failures — bytecode-serialize, defcomp-render, etc.)
+- HyperScript behavioral: 1478/1496 (run via `node tests/hs-kernel-eval.js`)
+- Active bugs: JIT combinator bug (11 HS failures), letrec+resume (browser-only)
+- E38 sourceInfo: 2/4 tests passing (tokenizer missing `:end`/`:line`, some spans incomplete)
+
+---
+
+## Phase 1 — Bug fixes
+
+### Step 1: Fix JIT closures-returning-closures
+
+**What:** `parse-bind`, `many`, `seq`, and other parser combinators that return closures
+miscompile under JIT. The compiled closure drops intermediate stack values when the
+callee itself returns a closure. 11 HyperScript tests fail under JIT, pass under CEK.
+
+**Root cause in `hosts/ocaml/lib/sx_vm.ml`:** When a JIT-compiled closure returns
+another closure (i.e. the callee is `VmClosure`), the frame restoration after the
+call incorrectly reuses the parent frame's locals slot, overwriting saved intermediate
+values. The `call_closure_reuse` path must snapshot `sp` before the inner call and
+restore it after, or bail to the non-reuse path for closures-returning-closures.
+
+**Verify:** `node tests/hs-kernel-eval.js 2>&1 | tail -3` — should go from 3116/3127 to 3127/3127.
+
+### Step 2: Fix letrec + perform resume (browser)
+
+**What:** In browser JIT mode, `letrec` sibling bindings are nil after a `perform`/resume
+cycle. `call_closure_reuse` in `sx_browser.ml` intentionally ignores `_saved_sp`, which
+strips the frame locals that `sf_letrec` was waiting on.
+
+**Fix:** In `sx_browser.ml`, the `VmSuspension` resume path must restore frame locals
+from the suspension snapshot before calling the continuation. Mirror what `sx_vm.ml`
+does in the non-browser case.
+
+**Verify:** Write a test in `spec/tests/` that does `(letrec ((f (fn () (perform :io nil)))) (f))` with a resume, check bindings survive. Runs under OCaml: `dune exec -- bin/run_tests.exe`.
+
+---
+
+## Phase 2 — Source info (E38 completion)
+
+Design: `plans/designs/e38-sourceinfo.md`. Target: 4/4 sourceInfo tests.
+
+The API (`hs-parse-ast`, `hs-source-for`, `hs-line-for`, `hs-node-get`, `hs-src`,
+`hs-src-at`, `hs-line-at`) and parser span wrapping (`hs-ast-wrap`, `hs-span-mode`)
+are already in the codebase. Two tests are passing; two fail because:
+- Tokenizer tokens lack `:end` and `:line` (only `:pos` today).
+- Some statement-level spans and `:next` field navigation are incomplete.
+
+### Step 3: Tokenizer — add `:end` and `:line` to tokens
+
+`lib/hyperscript/tokenizer.sx`: extend `hs-make-token` to `{:pos :end :value :type :line}`.
+Track a `current-line` counter (1-based, increments after `\n`). Update all ~20 emission
+sites. Mirror to `shared/static/wasm/sx/hs-tokenizer.sx` after edits.
+
+**Verify:** `(hs-make-token "NUMBER" "1" 0)` returns a dict with `:end` and `:line` keys.
+
+### Step 4: Complete parser spans + :next field
+
+`lib/hyperscript/parser.sx`: ensure `hs-ast-wrap` populates `:next` on every command
+in a `CommandList` (i.e. the following sibling command). Check that statement-level
+productions (if, for) correctly populate `:true-branch`. Trace through the two failing
+tests (`get source works for expressions`, `get line works for statements`) to find the
+exact missing fields or off-by-one positions.
+
+Mirror to `shared/static/wasm/sx/hs-parser.sx`.
+
+**Verify:** All 4 `hs-upstream-core/sourceInfo` tests pass.
+
+---
+
+## Phase 3 — Native ADTs (`define-type` / `match`)
+
+Design: `plans/designs/sx-adt.md`. No existing implementation.
+
+Impact: every language implementation (Haskell, Prolog, Lua, Common Lisp, Erlang)
+currently fakes sum types with `{:tag "..." :field ...}` dicts. Native ADTs remove
+that everywhere.
+
+### Step 5: OCaml — AdtValue type + `define-type` + basic `match`
+
+`hosts/ocaml/lib/sx_types.ml`:
+```ocaml
+type adt_value = { av_type: string; av_ctor: string; av_fields: value array }
+| AdtValue of adt_value
+```
+
+`hosts/ocaml/lib/sx_runtime.ml` (or evaluator):
+- `step-sf-define-type`: parse `(Name (Ctor1 f1 f2) (Ctor2) ...)`, register constructor
+  NativeFns, predicates (`Ctor1?`, `Name?`), field accessors (`Ctor1-f1`) via `env-bind!`.
+- `step-sf-match` + `MatchFrame`: linear scan of clauses; flat patterns only for 6a;
+  bind pattern variables in child env; `else` clause; raise on no match.
+- `type-of` returns the type name (e.g. `"Maybe"`).
+
+Write tests in `spec/tests/test-adt.sx`: basic constructor, predicate, accessor, match,
+else, no-match raise.
+
+**Verify:** `dune exec -- bin/run_tests.exe` — new test file all green.
+
+### Step 6: JS — AdtValue + `define-type` + `match`
+
+`hosts/javascript/platform.py`: add `AdtValue` as `{ _adt: true, _type, _ctor, _fields }`.
+Mirror `define-type` and `match` special forms in the JS evaluator.
+Retranspile: `python3 hosts/javascript/cli.py --output shared/static/scripts/sx-browser.js`
+
+**Verify:** `node hosts/javascript/run_tests.js` — adt tests pass on JS too.
+
+### Step 7: Nested patterns (Phase 6b)
+
+Both OCaml and JS `MatchFrame`: replace linear binding with recursive
+`matchPattern(pattern, value, env)` that:
+- Recurses into constructor sub-patterns.
+- Returns `{matched: bool, bindings: map}`.
+- Handles wildcard `_`, literals (`42`, `"str"`, `true`, `nil`).
+
+Extend `spec/tests/test-adt.sx` with nested pattern tests.
+
+### Step 8: Exhaustiveness warnings (Phase 6c)
+
+`_adt_registry: type_name → [ctor_names]` global populated by `define-type`.
+On first non-exhaustive `match` evaluation: `console.warn("[sx] match: non-exhaustive …")`.
+No error — warning only.
+
+---
+
+## Phase 4 — Plugin / extension system
+
+Design: `plans/designs/hs-plugin-system.md`.
+
+### Step 9: Parser feature registry
+
+`lib/hyperscript/parser.sx`: replace `parse-feat` hardcoded `cond` with a dict lookup.
+`(hs-register-feature! name parse-fn)` adds to the registry.
+
+### Step 10: Compiler command registry + `as` converter registry
+
+`lib/hyperscript/compiler.sx`: replace `hs-to-sx` hardcoded dispatch with dict.
+`(hs-register-command! name compile-fn)` and `(hs-register-converter! name convert-fn)`.
+
+### Step 11: Migrate hs-prolog-hook + Worker plugin
+
+`lib/hyperscript/runtime.sx`: remove `hs-prolog-hook`/`hs-set-prolog-hook!` ad-hoc
+slots. Create `lib/hyperscript/plugins/prolog.sx` that calls `hs-register-feature!`
+and `hs-register-command!`. Create `lib/hyperscript/plugins/worker.sx` replacing the
+E39 stub.
+
+---
+
+## Phase 5 — Performance
+
+These are incremental and can interleave with other phases.
+
+### Step 12: Frame records (CEK)
+
+`hosts/ocaml/lib/sx_runtime.ml`: represent CEK frames as OCaml records instead of
+tagged variant lists. Eliminates allocation pressure from list construction per frame.
+Profile before/after on a tight-loop benchmark.
+
+### Step 13: Buffer primitive for string building
+
+Add `make-buffer`, `buffer-append!`, `buffer->string` primitives. Eliminates the
+`(str a b c d ...)` quadratic allocation pattern in serializers and renderers.
+Wire into `sx_primitives.ml` and the JS platform.
+
+### Step 14: Inline common primitives in JIT
+
+`hosts/ocaml/lib/sx_vm.ml`: add `OP_ADD`, `OP_SUB`, `OP_EQ`, `OP_APPEND` specialised
+opcodes that skip the primitive table lookup for the most common calls. Compiler emits
+these when operands are known numbers/lists.
+
+---
+
+## Progress log
+
+| Step | Status | Commit |
+|------|--------|--------|
+| 1 — JIT combinator bug | [ ] | — |
+| 2 — letrec+resume | [ ] | — |
+| 3 — tokenizer :end/:line | [ ] | — |
+| 4 — parser spans complete | [ ] | — |
+| 5 — OCaml AdtValue + define-type + match | [ ] | — |
+| 6 — JS AdtValue + define-type + match | [ ] | — |
+| 7 — nested patterns | [ ] | — |
+| 8 — exhaustiveness warnings | [ ] | — |
+| 9 — parser feature registry | [ ] | — |
+| 10 — compiler + as converter registry | [ ] | — |
+| 11 — plugin migration + worker | [ ] | — |
+| 12 — frame records | [ ] | — |
+| 13 — buffer primitive | [ ] | — |
+| 14 — inline primitives JIT | [ ] | — |
+
+---
+
+## Rules
+
+- Branch: `architecture`. Never push to `main`.
+- SX files: `sx-tree` MCP tools only. `sx_validate` after every edit.
+- After every `.sx` edit to `lib/hyperscript/`, mirror to `shared/static/wasm/sx/hs-<file>.sx`.
+- OCaml build: `sx_build target="ocaml"` MCP tool (never raw `dune`).
+- JS build: `sx_build target="js"` MCP tool.
+- One step per commit. Update progress log in this file.
+- No new planning docs. No comments in SX unless non-obvious.
+- Unicode in SX: raw UTF-8 only, never `\uXXXX`.

plans/tcl-sx-completion.md

@@ -105,7 +105,9 @@ just Tcl.
 
 ---
 
-## Phase 4 — Optional: env-as-value (architectural)
+## Phase 4 — env-as-value (architectural) ✓
+
+
 
 `uplevel`/`upvar` required an explicit frame stack because SX environments
 aren't inspectable from user code. Adding:
@@ -146,6 +148,7 @@ becomes a lasting SX contribution used by every future hosted language.
 
 _Newest first._
 
+- 2026-05-06: Phase 4 env-as-value — current-env (special form via Sx_ref.register_special_form), eval-in-env (primitive in setup_evaluator_bridge), env-lookup + env-extend (in setup_env_operations); 5 idiom tests; 342/342 green
 - 2026-05-06: Phase 3 OCaml primitives — file-read/write/append/exists?/glob + clock-seconds/milliseconds/format in sx_primitives.ml + unix dep; tcl-cmd-clock/file wired up; 337/337 green
 - 2026-05-06: Phase 2 coroutine rewrite — `tcl-cmd-coroutine` now creates a `make-fiber`; `tcl-cmd-yield` calls `:coro-yield-fn` (threaded through interp); true suspension; 337/337 green
 - 2026-05-06: Phase 2 fiber.sx — `make-fiber`/`fiber-resume`/`fiber-done?` using call/cc + set!; bidirectional value passing; generator and echo tests pass