diff --git a/.beads/interactions.jsonl b/.beads/interactions.jsonl
index 8d362e0..77f6811 100644
--- a/.beads/interactions.jsonl
+++ b/.beads/interactions.jsonl
@@ -6,3 +6,6 @@
 {"id":"int-40cd8348","kind":"field_change","created_at":"2026-06-04T18:09:15.510649Z","actor":"Yogthos","issue_id":"jolt-nte","extra":{"field":"status","new_value":"closed","old_value":"open"}}
 {"id":"int-57f4d2b3","kind":"field_change","created_at":"2026-06-04T18:31:23.83434Z","actor":"Yogthos","issue_id":"jolt-9sb","extra":{"field":"status","new_value":"closed","old_value":"open"}}
 {"id":"int-f46da620","kind":"field_change","created_at":"2026-06-04T18:33:45.099148Z","actor":"Yogthos","issue_id":"jolt-ytt","extra":{"field":"status","new_value":"closed","old_value":"open"}}
+{"id":"int-677fb0a5","kind":"field_change","created_at":"2026-06-04T18:40:42.396722Z","actor":"Yogthos","issue_id":"jolt-40n","extra":{"field":"status","new_value":"closed","old_value":"open"}}
+{"id":"int-10c63325","kind":"field_change","created_at":"2026-06-04T18:40:43.31635Z","actor":"Yogthos","issue_id":"jolt-4z9","extra":{"field":"status","new_value":"closed","old_value":"open"}}
+{"id":"int-ba29d2c7","kind":"field_change","created_at":"2026-06-04T18:45:52.297233Z","actor":"Yogthos","issue_id":"jolt-gxr","extra":{"field":"status","new_value":"closed","old_value":"open"}}
diff --git a/.beads/issues.jsonl b/.beads/issues.jsonl
index 50d79cf..0ce18a4 100644
--- a/.beads/issues.jsonl
+++ b/.beads/issues.jsonl
@@ -4,9 +4,9 @@
 {"_type":"issue","id":"jolt-x8s","title":"CRITICAL: collections not callable as IFn (vector/map/set)","status":"closed","priority":1,"issue_type":"bug","owner":"yogthos@gmail.com","created_at":"2026-06-04T17:46:14Z","created_by":"Yogthos","updated_at":"2026-06-04T17:50:54Z","closed_at":"2026-06-04T17:50:54Z","dependency_count":0,"dependent_count":0,"comment_count":0}
 {"_type":"issue","id":"jolt-alz","title":"CRITICAL: self-referential lazy-seq/lazy-cat yields only literal prefix","status":"closed","priority":1,"issue_type":"bug","owner":"yogthos@gmail.com","created_at":"2026-06-04T17:46:13Z","created_by":"Yogthos","updated_at":"2026-06-04T18:09:15Z","closed_at":"2026-06-04T18:09:15Z","dependency_count":0,"dependent_count":0,"comment_count":0}
 {"_type":"issue","id":"jolt-wec","title":"CRITICAL: multi-collection map returns unrealized thunk","status":"closed","priority":1,"issue_type":"bug","owner":"yogthos@gmail.com","created_at":"2026-06-04T17:46:12Z","created_by":"Yogthos","updated_at":"2026-06-04T18:06:02Z","closed_at":"2026-06-04T18:06:02Z","dependency_count":0,"dependent_count":0,"comment_count":0}
-{"_type":"issue","id":"jolt-gxr","title":"HIGH: aliased namespace calls (require :as) don't resolve (s/join)","status":"open","priority":2,"issue_type":"bug","owner":"yogthos@gmail.com","created_at":"2026-06-04T18:09:58Z","created_by":"Yogthos","updated_at":"2026-06-04T18:09:58Z","dependency_count":0,"dependent_count":0,"comment_count":0}
-{"_type":"issue","id":"jolt-4z9","title":"HIGH: dispatch — multimethod :default, protocol-on-record, extend-protocol","status":"open","priority":2,"issue_type":"bug","owner":"yogthos@gmail.com","created_at":"2026-06-04T18:09:57Z","created_by":"Yogthos","updated_at":"2026-06-04T18:09:57Z","dependency_count":0,"dependent_count":0,"comment_count":0}
-{"_type":"issue","id":"jolt-40n","title":"HIGH: update/update-in/assoc-in fail on map literals (struct)","status":"open","priority":2,"issue_type":"bug","owner":"yogthos@gmail.com","created_at":"2026-06-04T18:09:56Z","created_by":"Yogthos","updated_at":"2026-06-04T18:09:56Z","dependency_count":0,"dependent_count":0,"comment_count":0}
+{"_type":"issue","id":"jolt-gxr","title":"HIGH: aliased namespace calls (require :as) don't resolve (s/join)","status":"closed","priority":2,"issue_type":"bug","owner":"yogthos@gmail.com","created_at":"2026-06-04T18:09:58Z","created_by":"Yogthos","updated_at":"2026-06-04T18:45:52Z","closed_at":"2026-06-04T18:45:52Z","dependency_count":0,"dependent_count":0,"comment_count":0}
+{"_type":"issue","id":"jolt-4z9","title":"HIGH: dispatch — multimethod :default, protocol-on-record, extend-protocol","status":"closed","priority":2,"issue_type":"bug","owner":"yogthos@gmail.com","created_at":"2026-06-04T18:09:57Z","created_by":"Yogthos","updated_at":"2026-06-04T18:40:43Z","closed_at":"2026-06-04T18:40:43Z","dependency_count":0,"dependent_count":0,"comment_count":0}
+{"_type":"issue","id":"jolt-40n","title":"HIGH: update/update-in/assoc-in fail on map literals (struct)","status":"closed","priority":2,"issue_type":"bug","owner":"yogthos@gmail.com","created_at":"2026-06-04T18:09:56Z","created_by":"Yogthos","updated_at":"2026-06-04T18:40:42Z","closed_at":"2026-06-04T18:40:42Z","dependency_count":0,"dependent_count":0,"comment_count":0}
 {"_type":"issue","id":"jolt-ytt","title":"HIGH: str semantics — (str nil)='nil' should be '', (str :b)='b' should be ':b'","status":"closed","priority":2,"issue_type":"bug","owner":"yogthos@gmail.com","created_at":"2026-06-04T18:09:56Z","created_by":"Yogthos","updated_at":"2026-06-04T18:33:45Z","closed_at":"2026-06-04T18:33:45Z","dependency_count":0,"dependent_count":0,"comment_count":0}
 {"_type":"issue","id":"jolt-9sb","title":"HIGH: destructuring gaps (nested seq, :strs, nested map, fn-param)","status":"closed","priority":2,"issue_type":"bug","owner":"yogthos@gmail.com","created_at":"2026-06-04T18:09:55Z","created_by":"Yogthos","updated_at":"2026-06-04T18:31:24Z","closed_at":"2026-06-04T18:31:24Z","dependency_count":0,"dependent_count":0,"comment_count":0}
 {"_type":"issue","id":"jolt-7dy","title":"MED: compiler path lacks IFn dispatch (collections-as-fn) — only interpreter fixed","status":"open","priority":3,"issue_type":"bug","owner":"yogthos@gmail.com","created_at":"2026-06-04T18:10:00Z","created_by":"Yogthos","updated_at":"2026-06-04T18:10:00Z","dependency_count":0,"dependent_count":0,"comment_count":0}
diff --git a/src/jolt/core.janet b/src/jolt/core.janet
index 7b019eb..a4de998 100644
--- a/src/jolt/core.janet
+++ b/src/jolt/core.janet
@@ -867,6 +867,15 @@
       (each x xs (array/push result (str-render-one x)))
       (string/join result ""))))
 
+(defn core-str-join
+  "clojure.string/join: stringify each element (Clojure semantics), then join."
+  [coll &opt sep]
+  (default sep "")
+  (let [items (realize-for-iteration coll)
+        parts @[]]
+    (each x items (array/push parts (str-render-one x)))
+    (string/join parts (str-render-one sep))))
+
 (defn core-name
   "Returns the name string of a keyword, symbol, or string."
   [x]
@@ -1975,7 +1984,7 @@
     "str-replace" string/replace
     "str-replace-all" string/replace-all
     "str-reverse-b" string/reverse
-    "str-join" string/join
+    "str-join" core-str-join
     "str-split" string/split
     "str-triml" string/triml
     "str-trimr" string/trimr
diff --git a/src/jolt/evaluator.janet b/src/jolt/evaluator.janet
index 825931b..980eb8d 100644
--- a/src/jolt/evaluator.janet
+++ b/src/jolt/evaluator.janet
@@ -3,6 +3,7 @@
 
 (use ./types)
 (use ./phm)
+(use ./reader)
 
 (defn- sym-name?
   [sym-s name-str]
@@ -129,6 +130,38 @@
   [sym-s]
   (if (sym-s :ns) (string (sym-s :ns) "/" (sym-s :name)) (sym-s :name)))
 
+(defn- ns->path
+  "Map a namespace name to its Jolt stdlib source path (dots->dirs, dashes->_)."
+  [ns-name]
+  (string "src/jolt/"
+          (string/replace-all "." "/" (string/replace-all "-" "_" ns-name))
+          ".clj"))
+
+(defn- load-ns-file
+  "Parse and evaluate every form in a .clj file in the given context."
+  [ctx path]
+  (var s (slurp path))
+  (while (> (length (string/trim s)) 0)
+    (def [f r] (parse-next s))
+    (set s r)
+    (when (not (nil? f)) (eval-form ctx @{} f))))
+
+(defn- maybe-require-ns
+  "If namespace ns-name isn't populated yet and a stdlib source file exists,
+  load it. Restores the current namespace afterwards (the file's `ns` form
+  changes it). No-op for already-loaded namespaces."
+  [ctx ns-name]
+  (let [ns (ctx-find-ns ctx ns-name)]
+    (when (and (= 0 (length (ns :mappings))) (not= ns-name "clojure.core"))
+      (let [path (ns->path ns-name)]
+        (when (os/stat path)
+          (let [saved (ctx-current-ns ctx)]
+            # Jolt stdlib files have no `ns` form; switch into the target ns so
+            # their defs intern there, then restore.
+            (ctx-set-current-ns ctx ns-name)
+            (load-ns-file ctx path)
+            (ctx-set-current-ns ctx saved)))))))
+
 (defn- eval-require
   [ctx spec]
   (let [ns-sym (in spec 0)
@@ -149,7 +182,7 @@
                 (set refer-syms (in spec (+ i 1)))
                 (set i slen))
               (++ i))))))
-    (ctx-find-ns ctx ns-name)
+    (maybe-require-ns ctx ns-name)
     (when alias
       (let [current-ns (ctx-find-ns ctx (ctx-current-ns ctx))]
         (ns-import current-ns alias ns-name)))