diff --git a/lib/js/runtime.sx b/lib/js/runtime.sx
index eb5fa1f8..dabc3795 100644
--- a/lib/js/runtime.sx
+++ b/lib/js/runtime.sx
@@ -3396,7 +3396,7 @@
           (and (>= idx 0) (< idx (len o)) (integer? idx))))
       (else false))))
 
-(define Object {:keys js-object-keys :getPrototypeOf js-object-get-prototype-of :isSealed js-object-is-sealed :seal js-object-seal :create js-object-create :isExtensible js-object-is-extensible :is js-object-is :setPrototypeOf js-object-set-prototype-of :getOwnPropertyNames js-object-get-own-property-names :getOwnPropertyDescriptors js-object-get-own-property-descriptors :defineProperty js-object-define-property :fromEntries js-object-from-entries :getOwnPropertyDescriptor js-object-get-own-property-descriptor :assign js-object-assign :isFrozen js-object-is-frozen :freeze js-object-freeze :values js-object-values :hasOwn js-object-has-own :prototype {:hasOwnProperty (fn (k) (let ((o (js-this))) (js-object-has-own o k))) :toLocaleString (fn () "[object Object]") :isPrototypeOf (fn (o) (let ((this-val (js-this))) (cond ((not (dict? o)) false) (else (let ((proto (if (contains? (keys o) "__proto__") (get o "__proto__") nil))) (cond ((= proto this-val) true) ((= proto nil) false) (else ((get (get Object "prototype") "isPrototypeOf") proto)))))))) :toString (fn () "[object Object]") :propertyIsEnumerable (fn (k) (let ((o (js-this))) (js-object-has-own o k))) :valueOf (fn () (js-this))} :__callable__ (fn (&rest args) (cond ((= (len args) 0) (dict)) ((or (= (nth args 0) nil) (js-undefined? (nth args 0))) (dict)) (else (nth args 0)))) :preventExtensions js-object-prevent-extensions :entries js-object-entries :defineProperties js-object-define-properties})
+(define Object {:keys js-object-keys :getPrototypeOf js-object-get-prototype-of :isSealed js-object-is-sealed :seal js-object-seal :create js-object-create :isExtensible js-object-is-extensible :is js-object-is :setPrototypeOf js-object-set-prototype-of :getOwnPropertyNames js-object-get-own-property-names :getOwnPropertyDescriptors js-object-get-own-property-descriptors :defineProperty js-object-define-property :fromEntries js-object-from-entries :getOwnPropertyDescriptor js-object-get-own-property-descriptor :assign js-object-assign :isFrozen js-object-is-frozen :freeze js-object-freeze :values js-object-values :hasOwn js-object-has-own :prototype {:hasOwnProperty (fn (k) (let ((o (js-this))) (js-object-has-own o k))) :toLocaleString (fn () "[object Object]") :isPrototypeOf (fn (o) (let ((this-val (js-this))) (cond ((not (dict? o)) false) (else (let ((proto (if (contains? (keys o) "__proto__") (get o "__proto__") nil))) (cond ((= proto this-val) true) ((= proto nil) false) (else ((get (get Object "prototype") "isPrototypeOf") proto)))))))) :toString (fn () "[object Object]") :propertyIsEnumerable (fn (k) (let ((o (js-this))) (js-object-has-own o k))) :valueOf (fn () (js-this))} :__callable__ (fn (&rest args) (cond ((= (len args) 0) (dict)) ((or (= (nth args 0) nil) (js-undefined? (nth args 0))) (dict)) ((= (type-of (nth args 0)) "string") (js-new-call String (list (nth args 0)))) ((= (js-typeof (nth args 0)) "number") (js-new-call Number (list (nth args 0)))) ((= (js-typeof (nth args 0)) "boolean") (js-new-call Boolean (list (nth args 0)))) (else (nth args 0)))) :preventExtensions js-object-prevent-extensions :entries js-object-entries :defineProperties js-object-define-properties})
 
 (dict-set! Object "length" 1)
 
diff --git a/lib/js/test262-scoreboard.json b/lib/js/test262-scoreboard.json
index dbce29c3..74da3b29 100644
--- a/lib/js/test262-scoreboard.json
+++ b/lib/js/test262-scoreboard.json
@@ -1,22 +1,22 @@
 {
   "totals": {
-    "pass": 78,
-    "fail": 15,
+    "pass": 77,
+    "fail": 16,
     "skip": 1,
     "timeout": 6,
     "total": 100,
     "runnable": 99,
-    "pass_rate": 78.8
+    "pass_rate": 77.8
   },
   "categories": [
     {
       "category": "built-ins/String",
       "total": 100,
-      "pass": 78,
-      "fail": 15,
+      "pass": 77,
+      "fail": 16,
       "skip": 1,
       "timeout": 6,
-      "pass_rate": 78.8,
+      "pass_rate": 77.8,
       "top_failures": [
         [
           "Test262Error (assertion failed)",
@@ -33,6 +33,10 @@
         [
           "SyntaxError (parse/unsupported syntax)",
           1
+        ],
+        [
+          "runner-error: sx_server closed stdout mid-epoch",
+          1
         ]
       ]
     }
@@ -53,9 +57,13 @@
     [
       "SyntaxError (parse/unsupported syntax)",
       1
+    ],
+    [
+      "runner-error: sx_server closed stdout mid-epoch",
+      1
     ]
   ],
   "pinned_commit": "d5e73fc8d2c663554fb72e2380a8c2bc1a318a33",
-  "elapsed_seconds": 158.2,
+  "elapsed_seconds": 238.6,
   "workers": 1
 }
\ No newline at end of file
diff --git a/lib/js/test262-scoreboard.md b/lib/js/test262-scoreboard.md
index 5535dd0a..08f92328 100644
--- a/lib/js/test262-scoreboard.md
+++ b/lib/js/test262-scoreboard.md
@@ -1,9 +1,9 @@
 # test262 scoreboard
 
 Pinned commit: `d5e73fc8d2c663554fb72e2380a8c2bc1a318a33`
-Wall time: 158.2s
+Wall time: 238.6s
 
-**Total:** 78/99 runnable passed (78.8%). Raw: pass=78 fail=15 skip=1 timeout=6 total=100.
+**Total:** 77/99 runnable passed (77.8%). Raw: pass=77 fail=16 skip=1 timeout=6 total=100.
 
 ## Top failure modes
 
@@ -11,18 +11,20 @@ Wall time: 158.2s
 - **6x** Timeout
 - **1x** ReferenceError (undefined symbol)
 - **1x** SyntaxError (parse/unsupported syntax)
+- **1x** runner-error: sx_server closed stdout mid-epoch
 
 ## Categories (worst pass-rate first, min 10 runnable)
 
 | Category | Pass | Fail | Skip | Timeout | Total | Pass % |
 |---|---:|---:|---:|---:|---:|---:|
-| built-ins/String | 78 | 15 | 1 | 6 | 100 | 78.8% |
+| built-ins/String | 77 | 16 | 1 | 6 | 100 | 77.8% |
 
 ## Per-category top failures (min 10 runnable, worst first)
 
-### built-ins/String  (78/99 — 78.8%)
+### built-ins/String  (77/99 — 77.8%)
 
 - **13x** Test262Error (assertion failed)
 - **6x** Timeout
 - **1x** ReferenceError (undefined symbol)
 - **1x** SyntaxError (parse/unsupported syntax)
+- **1x** runner-error: sx_server closed stdout mid-epoch
diff --git a/plans/js-on-sx.md b/plans/js-on-sx.md
index 63e99394..e4402347 100644
--- a/plans/js-on-sx.md
+++ b/plans/js-on-sx.md
@@ -158,6 +158,8 @@ Each item: implement → tests → update progress. Mark `[x]` when tests green.
 
 Append-only record of completed iterations. Loop writes one line per iteration: date, what was done, test count delta.
 
+- 2026-05-07 — **`Object(value)` wraps primitives in their corresponding wrapper.** Per ES spec, `Object('s') instanceof String === true`, `Object(42).constructor === Number`, etc. Was passing primitives through as-is, so `Object('s').constructor` was undefined. Added clauses to `Object.__callable__` that dispatch by `(type-of arg)` / `(js-typeof arg)`: strings → `js-new-call String`, numbers → `js-new-call Number`, booleans → `js-new-call Boolean`. The wrapper constructors already store `__js_string_value__` / `__js_number_value__` / `__js_boolean_value__` on `this`. built-ins/Object: 16/50 → 26/50. conformance.sh: 148/148.
+
 - 2026-05-07 — **`Object(null)` and `Object(undefined)` return a new empty object.** Per ES spec, `Object(value)` returns a new object when `value` is null or undefined; otherwise it returns `ToObject(value)`. Was returning the null/undefined argument itself, breaking `Object(null).toString()`. Added a clause to the `Object.__callable__` cond that detects `nil` or `js-undefined` first arg and falls through to `(dict)`. built-ins/Object: 15/50 → 16/50. conformance.sh: 148/148.
 
 - 2026-05-07 — **`js-num-from-string` uses SX `string->number` for exponent-form numbers.** Was computing `m * pow(10, e)` from a manual mantissa/exponent split; floating-point multiplication introduced rounding (`Number(".12345e-3") - 0.00012345 == 2.7e-20`). The SX `string->number` primitive parses the whole literal in one IEEE round, matching what JS literals do. When `string->number` returns nil (invalid form), fall back to the old `m * pow(10, e)` path. built-ins/Number: 42/50 → 43/50. conformance.sh: 148/148.