diff --git a/hosts/ocaml/lib/sx_primitives.ml b/hosts/ocaml/lib/sx_primitives.ml
index 0ed7b8cf..a61634f1 100644
--- a/hosts/ocaml/lib/sx_primitives.ml
+++ b/hosts/ocaml/lib/sx_primitives.ml
@@ -528,6 +528,183 @@ let () =
     | [Rational (_, d)] -> Integer d
     | [Integer _]       -> Integer 1
     | _ -> raise (Eval_error "denominator: expected rational or integer"));
+  (* printf-spec: apply one Tcl/printf format spec to one arg.
+     spec is like "%5.2f", "%-10s", "%x", "%c", "%d". Always starts with %
+     and ends with the conversion char.  Supports d i u x X o c s f e g.
+     Coerces arg to the right type per conversion. *)
+  register "printf-spec" (fun args ->
+    let spec_str, arg = match args with
+      | [String s; v] -> (s, v)
+      | _ -> raise (Eval_error "printf-spec: (spec arg)")
+    in
+    let n = String.length spec_str in
+    if n < 2 || spec_str.[0] <> '%' then
+      raise (Eval_error ("printf-spec: invalid spec " ^ spec_str));
+    let type_char = spec_str.[n - 1] in
+    let to_int v = match v with
+      | Integer i -> i
+      | Number f -> int_of_float f
+      | String s ->
+        let s = String.trim s in
+        (try int_of_string s
+         with _ ->
+           try int_of_float (float_of_string s)
+           with _ -> 0)
+      | Bool true -> 1 | Bool false -> 0
+      | _ -> 0
+    in
+    let to_float v = match v with
+      | Number f -> f
+      | Integer i -> float_of_int i
+      | String s ->
+        let s = String.trim s in
+        (try float_of_string s with _ -> 0.0)
+      | _ -> 0.0
+    in
+    let to_string v = match v with
+      | String s -> s
+      | Integer i -> string_of_int i
+      | Number f -> Sx_types.format_number f
+      | Bool true -> "1" | Bool false -> "0"
+      | Nil -> ""
+      | _ -> Sx_types.inspect v
+    in
+    try
+      match type_char with
+      | 'd' | 'i' ->
+        let fmt = Scanf.format_from_string spec_str "%d" in
+        String (Printf.sprintf fmt (to_int arg))
+      | 'u' ->
+        let fmt = Scanf.format_from_string spec_str "%u" in
+        String (Printf.sprintf fmt (to_int arg))
+      | 'x' ->
+        let fmt = Scanf.format_from_string spec_str "%x" in
+        String (Printf.sprintf fmt (to_int arg))
+      | 'X' ->
+        let fmt = Scanf.format_from_string spec_str "%X" in
+        String (Printf.sprintf fmt (to_int arg))
+      | 'o' ->
+        let fmt = Scanf.format_from_string spec_str "%o" in
+        String (Printf.sprintf fmt (to_int arg))
+      | 'c' ->
+        let n_val = to_int arg in
+        let body = String.sub spec_str 0 (n - 1) in
+        let fmt = Scanf.format_from_string (body ^ "s") "%s" in
+        String (Printf.sprintf fmt (String.make 1 (Char.chr (n_val land 0xff))))
+      | 's' ->
+        let fmt = Scanf.format_from_string spec_str "%s" in
+        String (Printf.sprintf fmt (to_string arg))
+      | 'f' ->
+        let fmt = Scanf.format_from_string spec_str "%f" in
+        String (Printf.sprintf fmt (to_float arg))
+      | 'e' ->
+        let fmt = Scanf.format_from_string spec_str "%e" in
+        String (Printf.sprintf fmt (to_float arg))
+      | 'E' ->
+        let fmt = Scanf.format_from_string spec_str "%E" in
+        String (Printf.sprintf fmt (to_float arg))
+      | 'g' ->
+        let fmt = Scanf.format_from_string spec_str "%g" in
+        String (Printf.sprintf fmt (to_float arg))
+      | 'G' ->
+        let fmt = Scanf.format_from_string spec_str "%G" in
+        String (Printf.sprintf fmt (to_float arg))
+      | _ -> raise (Eval_error ("printf-spec: unsupported conversion " ^ String.make 1 type_char))
+    with
+    | Eval_error _ as e -> raise e
+    | _ -> raise (Eval_error ("printf-spec: invalid format " ^ spec_str)));
+
+  (* scan-spec: apply one Tcl/scanf format spec to a string.
+     Returns (consumed-count . parsed-value), or nil on failure. *)
+  register "scan-spec" (fun args ->
+    let spec_str, str = match args with
+      | [String s; String input] -> (s, input)
+      | _ -> raise (Eval_error "scan-spec: (spec input)")
+    in
+    let n = String.length spec_str in
+    if n < 2 || spec_str.[0] <> '%' then
+      raise (Eval_error ("scan-spec: invalid spec " ^ spec_str));
+    let type_char = spec_str.[n - 1] in
+    let len = String.length str in
+    (* skip leading whitespace for non-%c/%s conversions *)
+    let i = ref 0 in
+    if type_char <> 'c' then
+      while !i < len && (str.[!i] = ' ' || str.[!i] = '\t' || str.[!i] = '\n') do incr i done;
+    let start = !i in
+    try
+      match type_char with
+      | 'd' | 'i' ->
+        let j = ref !i in
+        if !j < len && (str.[!j] = '-' || str.[!j] = '+') then incr j;
+        while !j < len && str.[!j] >= '0' && str.[!j] <= '9' do incr j done;
+        if !j > start && (str.[start] >= '0' && str.[start] <= '9'
+                         || (!j > start + 1 && (str.[start] = '-' || str.[start] = '+'))) then
+          let n_val = int_of_string (String.sub str start (!j - start)) in
+          let d = Hashtbl.create 2 in
+          Hashtbl.replace d "value" (Integer n_val);
+          Hashtbl.replace d "consumed" (Integer !j);
+          Dict d
+        else Nil
+      | 'x' | 'X' ->
+        let j = ref !i in
+        while !j < len &&
+              ((str.[!j] >= '0' && str.[!j] <= '9') ||
+               (str.[!j] >= 'a' && str.[!j] <= 'f') ||
+               (str.[!j] >= 'A' && str.[!j] <= 'F')) do incr j done;
+        if !j > start then
+          let n_val = int_of_string ("0x" ^ String.sub str start (!j - start)) in
+          let d = Hashtbl.create 2 in
+          Hashtbl.replace d "value" (Integer n_val);
+          Hashtbl.replace d "consumed" (Integer !j);
+          Dict d
+        else Nil
+      | 'o' ->
+        let j = ref !i in
+        while !j < len && str.[!j] >= '0' && str.[!j] <= '7' do incr j done;
+        if !j > start then
+          let n_val = int_of_string ("0o" ^ String.sub str start (!j - start)) in
+          let d = Hashtbl.create 2 in
+          Hashtbl.replace d "value" (Integer n_val);
+          Hashtbl.replace d "consumed" (Integer !j);
+          Dict d
+        else Nil
+      | 'f' | 'e' | 'g' ->
+        let j = ref !i in
+        if !j < len && (str.[!j] = '-' || str.[!j] = '+') then incr j;
+        while !j < len && ((str.[!j] >= '0' && str.[!j] <= '9') || str.[!j] = '.') do incr j done;
+        if !j < len && (str.[!j] = 'e' || str.[!j] = 'E') then begin
+          incr j;
+          if !j < len && (str.[!j] = '-' || str.[!j] = '+') then incr j;
+          while !j < len && str.[!j] >= '0' && str.[!j] <= '9' do incr j done
+        end;
+        if !j > start then
+          let f_val = float_of_string (String.sub str start (!j - start)) in
+          let d = Hashtbl.create 2 in
+          Hashtbl.replace d "value" (Number f_val);
+          Hashtbl.replace d "consumed" (Integer !j);
+          Dict d
+        else Nil
+      | 's' ->
+        let j = ref !i in
+        while !j < len && str.[!j] <> ' ' && str.[!j] <> '\t' && str.[!j] <> '\n' do incr j done;
+        if !j > start then
+          let d = Hashtbl.create 2 in
+          Hashtbl.replace d "value" (String (String.sub str start (!j - start)));
+          Hashtbl.replace d "consumed" (Integer !j);
+          Dict d
+        else Nil
+      | 'c' ->
+        if !i < len then
+          let d = Hashtbl.create 2 in
+          Hashtbl.replace d "value" (Integer (Char.code str.[!i]));
+          Hashtbl.replace d "consumed" (Integer (!i + 1));
+          Dict d
+        else Nil
+      | _ -> raise (Eval_error ("scan-spec: unsupported conversion " ^ String.make 1 type_char))
+    with
+    | Eval_error _ as e -> raise e
+    | _ -> Nil);
+
   register "parse-int" (fun args ->
     let parse_leading_int s =
       let len = String.length s in
@@ -3399,6 +3576,62 @@ let () =
       Nil
     | _ -> raise (Eval_error "channel-set-blocking!: (channel bool)"));
 
+  (* === Exec === run an external process; capture stdout *)
+  register "exec-process" (fun args ->
+    let items = match args with
+      | [List xs] | [ListRef { contents = xs }] -> xs
+      | _ -> raise (Eval_error "exec-process: (cmd-list)")
+    in
+    let argv = Array.of_list (List.map (function
+      | String s -> s
+      | v -> Sx_types.inspect v
+    ) items) in
+    if Array.length argv = 0 then raise (Eval_error "exec: empty command");
+    let (out_r, out_w) = Unix.pipe () in
+    let (err_r, err_w) = Unix.pipe () in
+    let pid =
+      try Unix.create_process argv.(0) argv Unix.stdin out_w err_w
+      with Unix.Unix_error (e, _, _) ->
+        Unix.close out_r; Unix.close out_w;
+        Unix.close err_r; Unix.close err_w;
+        raise (Eval_error ("exec: " ^ Unix.error_message e))
+    in
+    Unix.close out_w;
+    Unix.close err_w;
+    let buf = Buffer.create 256 in
+    let errbuf = Buffer.create 64 in
+    let chunk = Bytes.create 4096 in
+    let read_all fd target =
+      try
+        let stop = ref false in
+        while not !stop do
+          let n = Unix.read fd chunk 0 (Bytes.length chunk) in
+          if n = 0 then stop := true
+          else Buffer.add_subbytes target chunk 0 n
+        done
+      with _ -> ()
+    in
+    read_all out_r buf;
+    read_all err_r errbuf;
+    Unix.close out_r;
+    Unix.close err_r;
+    let (_, status) = Unix.waitpid [] pid in
+    let exit_code = match status with
+      | Unix.WEXITED n -> n
+      | Unix.WSIGNALED _ | Unix.WSTOPPED _ -> 1
+    in
+    let s = Buffer.contents buf in
+    let trimmed =
+      if String.length s > 0 && s.[String.length s - 1] = '\n'
+      then String.sub s 0 (String.length s - 1) else s
+    in
+    if exit_code <> 0 then
+      raise (Eval_error ("exec: child exited " ^ string_of_int exit_code
+                         ^ (if Buffer.length errbuf > 0
+                            then ": " ^ Buffer.contents errbuf
+                            else "")))
+    else String trimmed);
+
   (* === Sockets === wrapping Unix.socket/connect/bind/listen/accept *)
   let resolve_inet_addr host =
     if host = "" || host = "0.0.0.0" then Unix.inet_addr_any
diff --git a/lib/tcl/runtime.sx b/lib/tcl/runtime.sx
index e72928aa..666e92d7 100644
--- a/lib/tcl/runtime.sx
+++ b/lib/tcl/runtime.sx
@@ -73,59 +73,106 @@
   (fn (full-stack level)
     (nth full-stack level)))
 
+; True if name starts with "::" (absolute namespace reference; for now we
+; treat any "::name" as the global variable `name`). Multi-level namespace
+; paths like "::ns::var" are not yet split — they're stored under the
+; literal name in the global frame.
+; Hot path on every var-get/set; only one char-at on the typical fast path.
+(define
+  tcl-global-ref?
+  (fn (name)
+    (and
+      (equal? (char-at name 0) ":")
+      (equal? (char-at name 1) ":"))))
+
+(define
+  tcl-strip-global
+  (fn (name)
+    (substring name 2 (string-length name))))
+
 (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"))
+    (if
+      (tcl-global-ref? name)
+      ; absolute reference — look up in global (root) frame
+      (let
+        ((root-frame
+            (let ((stack (get interp :frame-stack)))
+              (if (= 0 (len stack)) (get interp :frame) (first stack))))
+          (gname (tcl-strip-global name)))
+        (let ((val (frame-lookup root-frame gname)))
+          (if
+            (nil? val)
+            (error (str "can't read \"" name "\": no such variable"))
+            val)))
+      (let
+        ((val (frame-lookup (get interp :frame) name)))
         (if
-          (upvar-alias? val)
-          ; follow alias to target frame
-          (let
-            ((target-level (get val :upvar-level))
-              (target-name (get val :upvar-name)))
+          (nil? val)
+          (error (str "can't read \"" name "\": no such variable"))
+          (if
+            (upvar-alias? val)
+            ; follow alias to target frame
             (let
-              ((full-stack (tcl-full-stack interp)))
+              ((target-level (get val :upvar-level))
+                (target-name (get val :upvar-name)))
               (let
-                ((target-frame (tcl-frame-nth full-stack target-level)))
+                ((full-stack (tcl-full-stack interp)))
                 (let
-                  ((target-val (frame-lookup target-frame target-name)))
-                  (if
-                    (nil? target-val)
-                    (error (str "can't read \"" name "\": no such variable"))
-                    target-val)))))
-          val)))))
+                  ((target-frame (tcl-frame-nth full-stack target-level)))
+                  (let
+                    ((target-val (frame-lookup target-frame target-name)))
+                    (if
+                      (nil? target-val)
+                      (error (str "can't read \"" name "\": no such variable"))
+                      target-val)))))
+            val))))))
 
 (define
   tcl-var-set
   (fn
     (interp name val)
-    (let
-      ((cur-val (get (get (get interp :frame) :locals) name)))
-      (if
-        (and (not (nil? cur-val)) (upvar-alias? cur-val))
-        ; set in target frame
+    (cond
+      ((tcl-global-ref? name)
+        ; absolute reference — set in global (root) frame
         (let
-          ((target-level (get cur-val :upvar-level))
-            (target-name (get cur-val :upvar-name)))
-          (let
-            ((full-stack (tcl-full-stack interp)))
+          ((stack (get interp :frame-stack)) (gname (tcl-strip-global name)))
+          (if
+            (= 0 (len stack))
+            ; no frame stack — current frame is the root
+            (assoc interp :frame (frame-set-top (get interp :frame) gname val))
             (let
-              ((target-frame (tcl-frame-nth full-stack target-level)))
+              ((root-frame (first stack))
+                (rest-stack (rest stack)))
+              (assoc
+                interp
+                :frame-stack
+                (cons (frame-set-top root-frame gname val) rest-stack))))))
+      (else
+        (let
+          ((cur-val (get (get (get interp :frame) :locals) name)))
+          (if
+            (and (not (nil? cur-val)) (upvar-alias? cur-val))
+            ; set in target frame
+            (let
+              ((target-level (get cur-val :upvar-level))
+                (target-name (get cur-val :upvar-name)))
               (let
-                ((updated-target (frame-set-top target-frame target-name val)))
+                ((full-stack (tcl-full-stack interp)))
                 (let
-                  ((new-full-stack (replace-at full-stack target-level updated-target)))
+                  ((target-frame (tcl-frame-nth full-stack target-level)))
                   (let
-                    ((new-frame-stack (take-n new-full-stack (- (len new-full-stack) 1)))
-                      (new-current (nth new-full-stack (- (len new-full-stack) 1))))
-                    (assoc interp :frame new-current :frame-stack new-frame-stack)))))))
-        ; normal set in current frame top
-        (assoc interp :frame (frame-set-top (get interp :frame) name val))))))
+                    ((updated-target (frame-set-top target-frame target-name val)))
+                    (let
+                      ((new-full-stack (replace-at full-stack target-level updated-target)))
+                      (let
+                        ((new-frame-stack (take-n new-full-stack (- (len new-full-stack) 1)))
+                          (new-current (nth new-full-stack (- (len new-full-stack) 1))))
+                        (assoc interp :frame new-current :frame-stack new-frame-stack)))))))
+            ; normal set in current frame top
+            (assoc interp :frame (frame-set-top (get interp :frame) name val))))))))
 
 (define
   tcl-eval-parts
@@ -292,15 +339,20 @@
                             (> (len result-stack) caller-stack-len)
                             (nth result-stack caller-stack-len)
                             (get interp :frame))))
-                      ; Forward result-interp as base so state changes inside
-                      ; the proc (e.g. :fileevents, :timers, :procs) propagate;
-                      ; restore caller's frame/stack/result/output/code.
-                      (assoc result-interp
+                      ; Forward state that must escape the proc body —
+                      ; :commands, :procs, :fileevents, :timers. Without this
+                      ; fileevent registrations made inside a proc body are
+                      ; lost on return (broke socket -async accept handlers).
+                      (assoc interp
                         :frame updated-caller
                         :frame-stack updated-below
                         :result result-val
                         :output (str caller-output proc-output)
-                        :code (if (= code 2) 0 code))))))))))))))
+                        :code (if (= code 2) 0 code)
+                        :commands (get result-interp :commands)
+                        :procs (get result-interp :procs)
+                        :fileevents (get result-interp :fileevents)
+                        :timers (get result-interp :timers))))))))))))))
 
 (define
   tcl-eval-cmd
@@ -1214,6 +1266,7 @@
           (tcl-fmt-scan-num chars (+ j 1) (str acc-n ch))
           {:num acc-n :j j})))))
 
+; Walk format string char by char; dispatch each %spec to printf-spec.
 (define
   tcl-fmt-apply
   (fn
@@ -1237,50 +1290,30 @@
             (if
               (>= i2 n-len)
               (str acc "%")
-              (let
-                ((c2 (nth chars i2)))
-                (if
-                  (equal? c2 "%")
-                  (tcl-fmt-apply
-                    chars
-                    n-len
-                    fmt-args
-                    (+ i2 1)
-                    arg-idx
-                    (str acc "%"))
-                  (let
-                    ((fr (tcl-fmt-scan-flags chars i2 "")))
+              (if
+                (equal? (nth chars i2) "%")
+                ; literal %%
+                (tcl-fmt-apply chars n-len fmt-args (+ i2 1) arg-idx (str acc "%"))
+                ; dispatch via printf-spec
+                (let
+                  ((j (tcl-fmt-find-end chars i2 n-len)))
+                  (if
+                    (>= j n-len)
+                    (str acc "?")
                     (let
-                      ((flags (get fr :flags)) (j (get fr :j)))
-                      (let
-                        ((wr (tcl-fmt-scan-num chars j "")))
-                        (let
-                          ((width (get wr :num)) (j2 (get wr :j)))
-                          (let
-                            ((j3 (if (and (< j2 n-len) (equal? (nth chars j2) ".")) (let ((pr (tcl-fmt-scan-num chars (+ j2 1) ""))) (get pr :j)) j2)))
-                            (if
-                              (>= j3 n-len)
-                              (str acc "?")
-                              (let
-                                ((type-char (nth chars j3))
-                                  (cur-arg
-                                    (if
-                                      (< arg-idx (len fmt-args))
-                                      (nth fmt-args arg-idx)
-                                      "")))
-                                (let
-                                  ((zero-pad? (contains? (split flags "") "0"))
-                                    (left-align?
-                                      (contains? (split flags "") "-")))
-                                  (let
-                                    ((formatted (cond ((or (equal? type-char "d") (equal? type-char "i")) (tcl-fmt-pad (str (parse-int cur-arg)) width zero-pad? left-align?)) ((equal? type-char "s") (tcl-fmt-pad cur-arg width false left-align?)) ((or (equal? type-char "f") (equal? type-char "g") (equal? type-char "e")) cur-arg) ((equal? type-char "x") (str (parse-int cur-arg))) ((equal? type-char "o") (str (parse-int cur-arg))) ((equal? type-char "c") cur-arg) (else (str "%" type-char)))))
-                                    (tcl-fmt-apply
-                                      chars
-                                      n-len
-                                      fmt-args
-                                      (+ j3 1)
-                                      (+ arg-idx 1)
-                                      (str acc formatted))))))))))))))))))))
+                      ((spec (str "%" (join "" (slice chars i2 (+ j 1)))))
+                        (cur-arg
+                          (if
+                            (< arg-idx (len fmt-args))
+                            (nth fmt-args arg-idx)
+                            "")))
+                      (tcl-fmt-apply
+                        chars
+                        n-len
+                        fmt-args
+                        (+ j 1)
+                        (+ arg-idx 1)
+                        (str acc (printf-spec spec cur-arg))))))))))))))
 
 ; --- string command helpers ---
 
@@ -1300,8 +1333,127 @@
             interp
             :result (tcl-fmt-apply chars n-len fmt-args 0 0 "")))))))
 
-; toupper/tolower via char tables
-(define tcl-cmd-scan (fn (interp args) (assoc interp :result "0")))
+; scan str fmt ?varName ...?  — printf-style parse.
+; Returns count of successful conversions. If varNames given, sets each to
+; its conversion result; otherwise returns the values as a list.
+(define
+  tcl-cmd-scan
+  (fn
+    (interp args)
+    (if
+      (< (len args) 2)
+      (error "scan: wrong # args")
+      (let
+        ((input (first args))
+          (fmt (nth args 1))
+          (var-names (slice args 2 (len args))))
+        (let
+          ((parsed
+              (tcl-scan-loop
+                input
+                (split fmt "")
+                (string-length fmt)
+                0
+                0
+                (list))))
+          (if
+            (= 0 (len var-names))
+            (assoc interp :result (tcl-list-build parsed))
+            (let
+              ((bind-loop
+                  (fn
+                    (i-interp i)
+                    (if
+                      (>= i (len var-names))
+                      i-interp
+                      (let
+                        ((v (if (< i (len parsed)) (str (nth parsed i)) "")))
+                        (bind-loop (tcl-var-set i-interp (nth var-names i) v) (+ i 1)))))))
+              (let ((bound (bind-loop interp 0)))
+                (assoc bound :result (str (len parsed)))))))))))
+
+; Loop helper: walk format chars, dispatch each %spec to scan-spec.
+(define
+  tcl-scan-loop
+  (fn
+    (input fmt-chars n-fmt fi pos values)
+    (if
+      (>= fi n-fmt)
+      values
+      (let
+        ((c (nth fmt-chars fi)))
+        (cond
+          ((equal? c "%")
+            (if
+              (>= (+ fi 1) n-fmt)
+              values
+              (let
+                ((j (tcl-fmt-find-end fmt-chars (+ fi 1) n-fmt)))
+                (if
+                  (>= j n-fmt)
+                  values
+                  (let
+                    ((spec (str "%" (join "" (slice fmt-chars (+ fi 1) (+ j 1)))))
+                      (rem-str (substring input pos (string-length input))))
+                    (let
+                      ((r (scan-spec spec rem-str)))
+                      (if
+                        (nil? r)
+                        values
+                        (tcl-scan-loop
+                          input
+                          fmt-chars
+                          n-fmt
+                          (+ j 1)
+                          (+ pos (get r :consumed))
+                          (append values (list (str (get r :value))))))))))))
+          ((or (equal? c " ") (equal? c "\t") (equal? c "\n"))
+            (tcl-scan-loop
+              input
+              fmt-chars
+              n-fmt
+              (+ fi 1)
+              (tcl-skip-ws input pos)
+              values))
+          (else
+            (if
+              (and
+                (< pos (string-length input))
+                (equal? c (substring input pos (+ pos 1))))
+              (tcl-scan-loop input fmt-chars n-fmt (+ fi 1) (+ pos 1) values)
+              values)))))))
+
+; Find end of a printf spec starting at fi (after '%'). Returns index of
+; the conversion character.
+(define
+  tcl-fmt-find-end
+  (fn
+    (chars i n)
+    (if
+      (>= i n)
+      i
+      (let
+        ((c (nth chars i)))
+        (cond
+          ((or (equal? c "-") (equal? c "+") (equal? c " ") (equal? c "0") (equal? c "#"))
+            (tcl-fmt-find-end chars (+ i 1) n))
+          ((or (equal? c ".") (and (>= c "0") (<= c "9")))
+            (tcl-fmt-find-end chars (+ i 1) n))
+          (else i))))))
+
+(define
+  tcl-skip-ws
+  (fn
+    (input pos)
+    (if
+      (>= pos (string-length input))
+      pos
+      (let
+        ((c (substring input pos (+ pos 1))))
+        (if
+          (or (equal? c " ") (equal? c "\t") (equal? c "\n"))
+          (tcl-skip-ws input (+ pos 1))
+          pos)))))
 
 (define
   tcl-glob-match
@@ -2042,6 +2194,123 @@
       ((all-elems (reduce (fn (acc s) (append acc (tcl-list-split s))) (list) args)))
       (assoc interp :result (tcl-list-build all-elems)))))
 
+; lassign list var ?var ...?  → assigns elements to vars; returns
+; remaining unassigned elements as a list (empty string if all consumed)
+(define
+  tcl-cmd-lassign
+  (fn
+    (interp args)
+    (if
+      (= 0 (len args))
+      (error "lassign: wrong # args")
+      (let
+        ((elems (tcl-list-split (first args))) (vars (rest args)))
+        (let
+          ((bind-loop
+              (fn
+                (i-interp i)
+                (if
+                  (>= i (len vars))
+                  i-interp
+                  (let
+                    ((var (nth vars i))
+                      (val (if (< i (len elems)) (nth elems i) "")))
+                    (bind-loop (tcl-var-set i-interp var val) (+ i 1)))))))
+          (let
+            ((bound (bind-loop interp 0)))
+            (let
+              ((leftover
+                  (if
+                    (> (len elems) (len vars))
+                    (slice elems (len vars) (len elems))
+                    (list))))
+              (assoc bound :result (tcl-list-build leftover)))))))))
+
+; lrepeat count ?elem ...?  → list with elem...  repeated count times
+(define
+  tcl-cmd-lrepeat
+  (fn
+    (interp args)
+    (if
+      (= 0 (len args))
+      (error "lrepeat: wrong # args")
+      (let
+        ((n (parse-int (first args))) (elems (rest args)))
+        (if
+          (or (< n 0) (= 0 (len elems)))
+          (assoc interp :result "")
+          (let
+            ((build
+                (fn
+                  (i acc)
+                  (if (= i 0) acc (build (- i 1) (append acc elems))))))
+            (assoc interp :result (tcl-list-build (build n (list))))))))))
+
+; lset varname index value  → set element at index in list-valued variable
+(define
+  tcl-cmd-lset
+  (fn
+    (interp args)
+    (if
+      (< (len args) 3)
+      (error "lset: wrong # args")
+      (let
+        ((varname (first args))
+          (idx (parse-int (nth args 1)))
+          (val (nth args 2)))
+        (let
+          ((cur (tcl-var-get interp varname)))
+          (let
+            ((elems (tcl-list-split cur)))
+            (if
+              (or (< idx 0) (>= idx (len elems)))
+              (error (str "lset: index out of range " idx))
+              (let
+                ((new-list (replace-at elems idx val)))
+                (let
+                  ((new-str (tcl-list-build new-list)))
+                  (assoc
+                    (tcl-var-set interp varname new-str)
+                    :result new-str))))))))))
+
+; lmap helper: like foreach-loop but collects body results
+(define
+  tcl-lmap-loop
+  (fn
+    (interp varname items body acc)
+    (if
+      (= 0 (len items))
+      (assoc interp :result (tcl-list-build acc))
+      (let
+        ((body-result (tcl-eval-string (tcl-var-set interp varname (first items)) body)))
+        (let
+          ((code (get body-result :code)))
+          (cond
+            ((= code 3) (assoc (assoc body-result :code 0) :result (tcl-list-build acc)))
+            ((= code 4) (tcl-lmap-loop (assoc body-result :code 0) varname (rest items) body acc))
+            ((= code 2) body-result)
+            ((= code 1) body-result)
+            (else
+              (tcl-lmap-loop
+                (assoc body-result :code 0)
+                varname
+                (rest items)
+                body
+                (append acc (list (get body-result :result)))))))))))
+
+(define
+  tcl-cmd-lmap
+  (fn
+    (interp args)
+    (if
+      (< (len args) 3)
+      (error "lmap: wrong # args")
+      (let
+        ((varname (first args))
+          (list-str (nth args 1))
+          (body (nth args 2)))
+        (tcl-lmap-loop interp varname (tcl-list-split list-str) body (list))))))
+
 ; --- dict command helpers ---
 
 ; Parse flat dict string into SX list of [key val] pairs
@@ -2316,6 +2585,51 @@
                       (assoc
                         (tcl-var-set interp varname new-dict)
                         :result new-dict)))))))
+          ((equal? sub "lappend")
+            ; dict lappend dictVarName key elem ?elem ...?
+            (let
+              ((varname (first rest-args))
+                (key (nth rest-args 1))
+                (new-elems (slice rest-args 2 (len rest-args))))
+              (let
+                ((cur (let ((v (if (nil? (frame-lookup (get interp :frame) varname)) nil (tcl-var-get interp varname)))) (if (nil? v) "" v))))
+                (let
+                  ((old-val (let ((v (tcl-dict-get cur key))) (if (nil? v) "" v))))
+                  (let
+                    ((merged (tcl-list-build (append (tcl-list-split old-val) new-elems))))
+                    (let
+                      ((new-dict (tcl-dict-set-pair cur key merged)))
+                      (assoc
+                        (tcl-var-set interp varname new-dict)
+                        :result new-dict)))))))
+          ((equal? sub "remove")
+            ; dict remove dict ?key ...?
+            (let
+              ((dict-str (first rest-args))
+                (keys-to-remove (rest rest-args)))
+              (assoc
+                interp
+                :result (reduce
+                  (fn (acc k) (tcl-dict-unset-key acc k))
+                  dict-str
+                  keys-to-remove))))
+          ((equal? sub "filter")
+            ; dict filter dict key pattern  — only `key` filter supported
+            (let
+              ((dict-str (first rest-args))
+                (mode (nth rest-args 1))
+                (pattern (nth rest-args 2)))
+              (if
+                (not (equal? mode "key"))
+                (error (str "dict filter: only key filter implemented, got " mode))
+                (let
+                  ((kept
+                      (filter
+                        (fn (pair) (tcl-glob-match (split pattern "") (split (first pair) "")))
+                        (tcl-dict-to-pairs dict-str))))
+                  (assoc
+                    interp
+                    :result (tcl-dict-from-pairs kept))))))
           (else (error (str "dict: unknown subcommand \"" sub "\""))))))))
 
 ; Qualify a proc name relative to current-ns.
@@ -2782,7 +3096,7 @@
             (let
               ((varname (first rest-args)))
               (let
-                ((val (frame-lookup (get interp :frame) varname)))
+                ((val (tcl-var-lookup-or-nil interp varname)))
                 (assoc interp :result (if (nil? val) "0" "1")))))
           ((equal? sub "hostname") (assoc interp :result "localhost"))
           ((equal? sub "script") (assoc interp :result ""))
@@ -3011,6 +3325,13 @@
   (fn
     (interp args)
     (let ((_ (channel-flush (first args)))) (assoc interp :result ""))))
+
+; exec cmd ?arg ...?  — run external process, return stdout (newline-stripped)
+(define
+  tcl-cmd-exec
+  (fn
+    (interp args)
+    (assoc interp :result (exec-process args))))
 (define
   tcl-cmd-fconfigure
   (fn
@@ -3223,6 +3544,22 @@
           (tcl-event-step interp (- target-ms now))
           target-ms)))))
 
+; Look up a Tcl var by name, returning nil instead of erroring if missing.
+; Handles `::var` global-prefix routing the same way tcl-var-get does.
+(define
+  tcl-var-lookup-or-nil
+  (fn
+    (interp name)
+    (if
+      (tcl-global-ref? name)
+      (let
+        ((root-frame
+            (let ((stack (get interp :frame-stack)))
+              (if (= 0 (len stack)) (get interp :frame) (first stack))))
+          (gname (tcl-strip-global name)))
+        (frame-lookup root-frame gname))
+      (frame-lookup (get interp :frame) name))))
+
 (define
   tcl-cmd-vwait
   (fn
@@ -3233,7 +3570,7 @@
       (let
         ((name (first args)))
         (let
-          ((initial (frame-lookup (get interp :frame) name)))
+          ((initial (tcl-var-lookup-or-nil interp name)))
           (assoc (tcl-vwait-loop interp name initial) :result ""))))))
 
 (define
@@ -3241,7 +3578,7 @@
   (fn
     (interp name initial)
     (let
-      ((cur (frame-lookup (get interp :frame) name)))
+      ((cur (tcl-var-lookup-or-nil interp name)))
       (if
         (and (not (nil? cur)) (not (equal? cur initial)))
         interp
@@ -3783,6 +4120,16 @@
                                                                     ((i (tcl-register i "linsert" tcl-cmd-linsert)))
                                                                     (let
                                                                       ((i (tcl-register i "concat" tcl-cmd-concat)))
+                                                                      (let
+                                                                        ((i (tcl-register i "lassign" tcl-cmd-lassign)))
+                                                                      (let
+                                                                        ((i (tcl-register i "lrepeat" tcl-cmd-lrepeat)))
+                                                                      (let
+                                                                        ((i (tcl-register i "lset" tcl-cmd-lset)))
+                                                                      (let
+                                                                        ((i (tcl-register i "lmap" tcl-cmd-lmap)))
+                                                                      (let
+                                                                        ((i (tcl-register i "exec" tcl-cmd-exec)))
                                                                       (let
                                                                         ((i (tcl-register i "split" tcl-cmd-split)))
                                                                         (let
@@ -3856,4 +4203,4 @@
                                                                                                                                 (tcl-register
                                                                                                                                   i
                                                                                                                                   "array"
-                                                                                                                                  tcl-cmd-array)))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))
+                                                                                                                                  tcl-cmd-array))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))
diff --git a/lib/tcl/test.sh b/lib/tcl/test.sh
index fb24a662..e42fbfa2 100755
--- a/lib/tcl/test.sh
+++ b/lib/tcl/test.sh
@@ -59,7 +59,7 @@ cat > "$TMPFILE" << EPOCHS
 (eval "tcl-test-summary")
 EPOCHS
 
-OUTPUT=$(timeout 2400 "$SX_SERVER" < "$TMPFILE" 2>&1)
+OUTPUT=$(timeout 7200 "$SX_SERVER" < "$TMPFILE" 2>&1)
 [ "$VERBOSE" = "-v" ] && echo "$OUTPUT"
 
 # Extract summary line from epoch 11 output
diff --git a/lib/tcl/tests/idioms.sx b/lib/tcl/tests/idioms.sx
index b6df6180..7b8e1160 100644
--- a/lib/tcl/tests/idioms.sx
+++ b/lib/tcl/tests/idioms.sx
@@ -415,6 +415,115 @@
         :result)
       "")
 
+    ; 60-63. Phase 6a namespace :: prefix
+    (ok "ns-set-from-proc-reaches-global"
+      (get
+        (run
+          "proc f {x} { set ::g $x }\nf hello\nset ::g")
+        :result)
+      "hello")
+
+    (ok "ns-read-from-proc"
+      (get
+        (run
+          "set ::v 42\nproc f {} { return $::v }\nf")
+        :result)
+      "42")
+
+    (ok "ns-incr-via-prefix"
+      (get
+        (run
+          "set ::n 5\nproc bump {} { incr ::n }\nbump\nbump\nset ::n")
+        :result)
+      "7")
+
+    (ok "ns-different-from-local"
+      (get
+        (run
+          "set x outer\nproc f {} { set x inner; set ::x global; return $x }\nf")
+        :result)
+      "inner")
+
+    ; 64-69. Phase 6b list ops (lassign, lrepeat, lset, lmap)
+    (ok "lassign-three"
+      (get (run "lassign {a b c d e} x y z\nlist $x $y $z") :result)
+      "a b c")
+
+    (ok "lassign-leftover"
+      (get (run "lassign {1 2 3 4 5} a b") :result)
+      "3 4 5")
+
+    (ok "lrepeat-basic"
+      (get (run "lrepeat 3 a") :result)
+      "a a a")
+
+    (ok "lrepeat-multi"
+      (get (run "lrepeat 2 x y") :result)
+      "x y x y")
+
+    (ok "lset-replaces"
+      (get (run "set L {a b c d}\nlset L 2 ZZ\nset L") :result)
+      "a b ZZ d")
+
+    (ok "lmap-square"
+      (get (run "lmap n {1 2 3 4} {expr {$n * $n}}") :result)
+      "1 4 9 16")
+
+    ; 70-72. Phase 6c dict additions (lappend, remove, filter)
+    (ok "dict-lappend-extends"
+      (get (run "set d {tags {a b}}\ndict lappend d tags c d\nset d") :result)
+      "tags {a b c d}")
+
+    (ok "dict-remove"
+      (get (run "dict remove {a 1 b 2 c 3} b") :result)
+      "a 1 c 3")
+
+    (ok "dict-filter-key"
+      (get (run "dict filter {alpha 1 beta 2 gamma 3} key a*") :result)
+      "alpha 1")
+
+    ; 73-79. Phase 6d format and scan
+    (ok "format-int-padded"
+      (get (run "format {%05d} 42") :result)
+      "00042")
+
+    (ok "format-float-precision"
+      (get (run "format {%.2f} 3.14159") :result)
+      "3.14")
+
+    (ok "format-hex"
+      (get (run "format {%x} 255") :result)
+      "ff")
+
+    (ok "format-char"
+      (get (run "format {%c} 65") :result)
+      "A")
+
+    (ok "format-string-left"
+      (get (run "format {%-5s|} hi") :result)
+      "hi   |")
+
+    (ok "scan-two-ints"
+      (get (run "scan {12 34} {%d %d} a b\nlist $a $b") :result)
+      "12 34")
+
+    (ok "scan-count"
+      (get (run "scan {hello 42} {%s %d}") :result)
+      "hello 42")
+
+    ; 80-82. Phase 6e exec
+    (ok "exec-echo"
+      (get (run "exec echo hello world") :result)
+      "hello world")
+
+    (ok "exec-printf-no-newline"
+      (get (run "exec /bin/printf x") :result)
+      "x")
+
+    (ok "exec-with-args"
+      (get (run "exec /bin/echo -n test") :result)
+      "test")
+
     (dict
       "passed"
       tcl-idiom-pass
diff --git a/lib/tcl/tokenizer.sx b/lib/tcl/tokenizer.sx
index bc094ff3..d95135bf 100644
--- a/lib/tcl/tokenizer.sx
+++ b/lib/tcl/tokenizer.sx
@@ -158,7 +158,9 @@
                       (begin
                         (when (= (cur) "}") (advance! 1))
                         {:type "var" :name name}))))))
-            ((tcl-ident-start? (cur))
+            ((or
+                (tcl-ident-start? (cur))
+                (and (= (cur) ":") (= (char-at 1) ":")))
               (let ((start pos))
                 (begin
                   (scan-ns-name!)