VM spec in SX + 72 tests passing on both JS and OCaml

spec/vm.sx — bytecode VM written in SX (the spec):
  - Stack-based interpreter for bytecode from compiler.sx
  - 24 opcodes: constants, variables (local/upvalue/global), control flow,
    function calls (with TCO), closures with upvalue capture, collections,
    string concat, define
  - Upvalue cells for shared mutable closure variables
  - Call dispatch: vm-closure (fast path), native-fn, CEK fallback
  - Platform interface: 7 primitives (vm-stack-*, call-primitive, cek-call,
    get-primitive, env-parent)

spec/tests/test-vm.sx — 72 tests exercising compile→bytecode→VM pipeline:
  constants, arithmetic, comparison, control flow (if/when/cond/case/and/or),
  let bindings, lambda, closures, upvalue mutation, TCO (10K iterations),
  collections, strings, define, letrec, quasiquote, threading, integration
  (fibonacci, recursive map/filter/reduce, compose)

spec/compiler.sx — fix :else keyword detection in case/cond compilation
  (was comparing Keyword object to evaluated string, now checks type)

Platform primitives added (JS + OCaml):
  make-vm-stack, vm-stack-get, vm-stack-set!, vm-stack-length, vm-stack-copy!,
  primitive?, get-primitive, call-primitive, set-nth! (JS)

Test runners updated to load bytecode.sx + compiler.sx + vm.sx for --full.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

hosts/javascript/platform.py

@@ -63,11 +63,12 @@ SPEC_MODULES = {
     "signals": ("signals.sx", "signals (reactive signal runtime)"),
     "page-helpers": ("page-helpers.sx", "page-helpers (pure data transformation helpers)"),
     "types": ("types.sx", "types (gradual type system)"),
+    "vm": ("vm.sx", "vm (bytecode virtual machine)"),
 }
 # Note: frames and cek are now part of evaluator.sx (always loaded as core)
 
 # Explicit ordering for spec modules with dependencies.
-SPEC_MODULE_ORDER = ["deps", "page-helpers", "router", "signals", "types"]
+SPEC_MODULE_ORDER = ["deps", "page-helpers", "router", "signals", "types", "vm"]
 
 
 EXTENSION_NAMES = {"continuations"}
@@ -1139,6 +1140,44 @@ PRIMITIVES_JS_MODULES: dict[str, str] = {
   }
   PRIMITIVES["scope-emit!"] = scopeEmit;
   PRIMITIVES["scope-peek"] = scopePeek;
+
+  // ---- VM stack primitives ----
+  // The VM spec (vm.sx) requires these array-like operations.
+  // In JS, a plain Array serves as the stack.
+  PRIMITIVES["make-vm-stack"] = function(size) {
+    var a = new Array(size);
+    for (var i = 0; i < size; i++) a[i] = NIL;
+    return a;
+  };
+  PRIMITIVES["vm-stack-get"] = function(stack, idx) { return stack[idx]; };
+  PRIMITIVES["vm-stack-set!"] = function(stack, idx, value) { stack[idx] = value; return NIL; };
+  PRIMITIVES["vm-stack-length"] = function(stack) { return stack.length; };
+  PRIMITIVES["vm-stack-copy!"] = function(src, dst, count) {
+    for (var i = 0; i < count; i++) dst[i] = src[i];
+    return NIL;
+  };
+  PRIMITIVES["get-primitive"] = function(name) {
+    if (name in PRIMITIVES) return PRIMITIVES[name];
+    throw new Error("VM undefined: " + name);
+  };
+  PRIMITIVES["call-primitive"] = function(name, args) {
+    if (!(name in PRIMITIVES)) throw new Error("VM undefined: " + name);
+    var fn = PRIMITIVES[name];
+    return fn.apply(null, Array.isArray(args) ? args : []);
+  };
+  PRIMITIVES["primitive?"] = function(name) {
+    return name in PRIMITIVES;
+  };
+  PRIMITIVES["set-nth!"] = function(lst, idx, val) {
+    lst[idx] = val;
+    return NIL;
+  };
+  PRIMITIVES["env-parent"] = function(env) {
+    if (env && Object.getPrototypeOf(env) !== Object.prototype &&
+        Object.getPrototypeOf(env) !== null)
+      return Object.getPrototypeOf(env);
+    return NIL;
+  };
 ''',
 }
 # Modules to include by default (all)

hosts/javascript/run_tests.js

@@ -81,6 +81,7 @@ env["env-extend"] = function(e) { return Object.create(e); };
 env["env-merge"] = function(a, b) { return Object.assign({}, a, b); };
 
 // Missing primitives referenced by tests
+// primitive? is now in platform.py PRIMITIVES
 env["upcase"] = function(s) { return s.toUpperCase(); };
 env["downcase"] = function(s) { return s.toLowerCase(); };
 env["make-keyword"] = function(name) { return new Sx.Keyword(name); };
@@ -277,6 +278,23 @@ for (const expr of frameworkExprs) {
   Sx.eval(expr, env);
 }
 
+// Load compiler + VM spec when running full tests
+if (fullBuild) {
+  const specDir = path.join(projectDir, "spec");
+  for (const specFile of ["bytecode.sx", "compiler.sx", "vm.sx"]) {
+    const specPath = path.join(specDir, specFile);
+    if (fs.existsSync(specPath)) {
+      const src = fs.readFileSync(specPath, "utf8");
+      const exprs = Sx.parse(src);
+      for (const expr of exprs) {
+        try { Sx.eval(expr, env); } catch (e) {
+          console.error(`Error loading ${specFile}: ${e.message}`);
+        }
+      }
+    }
+  }
+}
+
 // Determine which tests to run
 const args = process.argv.slice(2).filter(a => !a.startsWith("--"));
 let testFiles = [];
@@ -293,7 +311,7 @@ if (args.length > 0) {
   }
 } else {
   // Tests requiring optional modules (only run with --full)
-  const requiresFull = new Set(["test-continuations.sx", "test-types.sx", "test-freeze.sx"]);
+  const requiresFull = new Set(["test-continuations.sx", "test-continuations-advanced.sx", "test-types.sx", "test-freeze.sx", "test-vm.sx"]);
   // All spec tests
   for (const f of fs.readdirSync(specTests).sort()) {
     if (f.startsWith("test-") && f.endsWith(".sx") && f !== "test-framework.sx") {