Serializable CEK state: cek-freeze and cek-thaw

Freeze a CEK state to pure s-expressions. Thaw it back to a live
state and resume with cek-run. Full round-trip through SX text works:
freeze → sx-serialize → sx-parse → thaw → resume → same result.

- cek-freeze: serialize control/env/kont/value to SX dicts
- cek-thaw: reconstruct live state from frozen SX
- Native functions serialize as (primitive "name"), looked up on resume
- Lambdas serialize as (lambda (params) body)
- Environments serialize as flat dicts of visible bindings
- Continuation frames serialize as typed dicts

Enables: localStorage persistence, content-addressed computation,
cross-machine migration, time-travel debugging.

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

shared/static/scripts/sx-browser.js

@@ -14,7 +14,7 @@
   // =========================================================================
 
   var NIL = Object.freeze({ _nil: true, toString: function() { return "nil"; } });
-  var SX_VERSION = "2026-03-14T20:39:57Z";
+  var SX_VERSION = "2026-03-14T22:10:44Z";
 
   function isNil(x) { return x === NIL || x === null || x === undefined; }
   function isSxTruthy(x) { return x !== false && !isNil(x); }
@@ -5283,6 +5283,74 @@ PRIMITIVES["eval-expr-cek"] = evalExprCek;
   var trampolineCek = function(val) { return (isSxTruthy(isThunk(val)) ? evalExprCek(thunkExpr(val), thunkEnv(val)) : val); };
 PRIMITIVES["trampoline-cek"] = trampolineCek;
 
+  // primitive-name
+  var primitiveName = function(f) { return (isSxTruthy(isLambda(f)) ? lambdaName(f) : (function() {
+  var result = NIL;
+  var names = ["+", "-", "*", "/", "=", "<", ">", "<=", ">=", "not", "and", "or", "str", "len", "first", "rest", "nth", "list", "cons", "append", "map", "filter", "reduce", "for-each", "some", "every?", "get", "keys", "dict", "dict?", "has-key?", "assoc", "empty?", "nil?", "number?", "string?", "list?", "type-of", "identity", "inc", "dec", "mod", "join", "split", "slice", "contains?", "starts-with?", "upper", "lower", "trim", "replace", "format"];
+  { var _c = names; for (var _i = 0; _i < _c.length; _i++) { var name = _c[_i]; if (isSxTruthy((isSxTruthy(isNil(result)) && isSxTruthy(isPrimitive(name)) && isIdentical(f, getPrimitive(name))))) {
+  result = name;
+} } }
+  return result;
+})()); };
+PRIMITIVES["primitive-name"] = primitiveName;
+
+  // cek-serialize-value
+  var cekSerializeValue = function(val) { return (isSxTruthy(isNil(val)) ? NIL : (isSxTruthy(isNumber(val)) ? val : (isSxTruthy(isString(val)) ? val : (isSxTruthy((typeOf(val) == "boolean")) ? val : (isSxTruthy((typeOf(val) == "symbol")) ? val : (isSxTruthy((typeOf(val) == "keyword")) ? val : (isSxTruthy(isList(val)) ? map(cekSerializeValue, val) : (isSxTruthy(isLambda(val)) ? [makeSymbol("lambda"), lambdaParams(val), lambdaBody(val)] : (isSxTruthy(isCallable(val)) ? [makeSymbol("primitive"), sxOr(primitiveName(val), "?")] : (isSxTruthy(isDict(val)) ? cekSerializeEnv(val) : (String(val)))))))))))); };
+PRIMITIVES["cek-serialize-value"] = cekSerializeValue;
+
+  // cek-serialize-env
+  var cekSerializeEnv = function(env) { return (function() {
+  var result = {};
+  var ks = keys(env);
+  { var _c = ks; for (var _i = 0; _i < _c.length; _i++) { var k = _c[_i]; result[k] = cekSerializeValue(get(env, k)); } }
+  return result;
+})(); };
+PRIMITIVES["cek-serialize-env"] = cekSerializeEnv;
+
+  // cek-serialize-frame
+  var cekSerializeFrame = function(frame) { return (function() {
+  var result = {};
+  var ks = keys(frame);
+  { var _c = ks; for (var _i = 0; _i < _c.length; _i++) { var k = _c[_i]; (function() {
+  var v = get(frame, k);
+  return dictSet(result, k, (isSxTruthy((k == "type")) ? v : (isSxTruthy((k == "tag")) ? v : (isSxTruthy((k == "f")) ? cekSerializeValue(v) : (isSxTruthy((k == "env")) ? cekSerializeEnv(v) : (isSxTruthy((k == "evaled")) ? map(cekSerializeValue, v) : (isSxTruthy((k == "remaining")) ? v : (isSxTruthy((k == "results")) ? map(cekSerializeValue, v) : (isSxTruthy((k == "raw-args")) ? v : (isSxTruthy((k == "current-item")) ? cekSerializeValue(v) : (isSxTruthy((k == "name")) ? v : (isSxTruthy((k == "update-fn")) ? cekSerializeValue(v) : (isSxTruthy((k == "first-render")) ? v : cekSerializeValue(v))))))))))))));
+})(); } }
+  return result;
+})(); };
+PRIMITIVES["cek-serialize-frame"] = cekSerializeFrame;
+
+  // cek-freeze
+  var cekFreeze = function(state) { return {["phase"]: get(state, "phase"), ["control"]: get(state, "control"), ["value"]: cekSerializeValue(get(state, "value")), ["env"]: cekSerializeEnv(get(state, "env")), ["kont"]: map(cekSerializeFrame, get(state, "kont"))}; };
+PRIMITIVES["cek-freeze"] = cekFreeze;
+
+  // cek-thaw-value
+  var cekThawValue = function(val) { return (isSxTruthy(isNil(val)) ? NIL : (isSxTruthy(isNumber(val)) ? val : (isSxTruthy(isString(val)) ? val : (isSxTruthy((typeOf(val) == "boolean")) ? val : (isSxTruthy((typeOf(val) == "symbol")) ? val : (isSxTruthy((typeOf(val) == "keyword")) ? val : (isSxTruthy((isSxTruthy(isList(val)) && isSxTruthy(!isSxTruthy(isEmpty(val))) && isSxTruthy((typeOf(first(val)) == "symbol")) && (symbolName(first(val)) == "primitive"))) ? getPrimitive(nth(val, 1)) : (isSxTruthy((isSxTruthy(isList(val)) && isSxTruthy(!isSxTruthy(isEmpty(val))) && isSxTruthy((typeOf(first(val)) == "symbol")) && (symbolName(first(val)) == "lambda"))) ? makeLambda(nth(val, 1), nth(val, 2), {}) : (isSxTruthy(isList(val)) ? map(cekThawValue, val) : (isSxTruthy(isDict(val)) ? cekThawEnv(val) : val)))))))))); };
+PRIMITIVES["cek-thaw-value"] = cekThawValue;
+
+  // cek-thaw-env
+  var cekThawEnv = function(frozenEnv) { return (function() {
+  var result = makeEnv();
+  { var _c = keys(frozenEnv); for (var _i = 0; _i < _c.length; _i++) { var k = _c[_i]; envSet(result, k, cekThawValue(get(frozenEnv, k))); } }
+  return result;
+})(); };
+PRIMITIVES["cek-thaw-env"] = cekThawEnv;
+
+  // cek-thaw-frame
+  var cekThawFrame = function(frozenFrame) { return (function() {
+  var result = {};
+  var ks = keys(frozenFrame);
+  { var _c = ks; for (var _i = 0; _i < _c.length; _i++) { var k = _c[_i]; (function() {
+  var v = get(frozenFrame, k);
+  return dictSet(result, k, (isSxTruthy((k == "type")) ? v : (isSxTruthy((k == "tag")) ? v : (isSxTruthy((k == "f")) ? cekThawValue(v) : (isSxTruthy((k == "env")) ? cekThawEnv(v) : (isSxTruthy((k == "evaled")) ? map(cekThawValue, v) : (isSxTruthy((k == "remaining")) ? v : (isSxTruthy((k == "results")) ? map(cekThawValue, v) : (isSxTruthy((k == "raw-args")) ? v : (isSxTruthy((k == "current-item")) ? cekThawValue(v) : (isSxTruthy((k == "name")) ? v : (isSxTruthy((k == "update-fn")) ? cekThawValue(v) : (isSxTruthy((k == "first-render")) ? v : cekThawValue(v))))))))))))));
+})(); } }
+  return result;
+})(); };
+PRIMITIVES["cek-thaw-frame"] = cekThawFrame;
+
+  // cek-thaw
+  var cekThaw = function(frozen) { return {["phase"]: get(frozen, "phase"), ["control"]: get(frozen, "control"), ["value"]: cekThawValue(get(frozen, "value")), ["env"]: cekThawEnv(get(frozen, "env")), ["kont"]: map(cekThawFrame, get(frozen, "kont"))}; };
+PRIMITIVES["cek-thaw"] = cekThaw;
+
 
   // === Transpiled from signals (reactive signal runtime) ===