forth: TCO at colon-def endings (no extra frame on tail-call ops)

lib/forth/compiler.sx

@@ -274,15 +274,27 @@
         (first cs)
         (forth-find-do (rest cs))))))
 
+;; Run a colon-def body. The PC is a one-cell dict so step-op can mutate
+;; it for branches/loops/exit. As an explicit TCO, when we reach the
+;; final op AND it's a plain function (not a branch dict), call it in
+;; tail position — no recurse, no post-increment — so chains of
+;; colon-def `: A ... B ;` calls don't accumulate continuation frames.
 (define
   forth-run-body
   (fn
     (s ops pc n)
     (when
       (< (get pc "v") n)
-      (begin
-        (forth-step-op s (nth ops (get pc "v")) pc)
-        (forth-run-body s ops pc n)))))
+      (let
+        ((cur (get pc "v")))
+        (let
+          ((op (nth ops cur)))
+          (if
+            (and (not (dict? op)) (= (+ cur 1) n))
+            (op s)
+            (begin
+              (forth-step-op s op pc)
+              (forth-run-body s ops pc n))))))))
 
 ;; Override forth-interpret-token to branch on compile mode.
 (define