diff --git a/src/jolt/backend.janet b/src/jolt/backend.janet
index cac8ee9..5ed8c52 100644
--- a/src/jolt/backend.janet
+++ b/src/jolt/backend.janet
@@ -292,12 +292,15 @@
       # leaves ctx-current-ns set to that fn's defining ns (it can't restore on
       # unwind), which then breaks alias resolution in the catching ns. Snapshot
       # the ns at try entry, reset it on catch (mirrors the interpreter's try).
-      (let [saved (gsym)]
+      (let [saved (gsym) raw (gsym)]
         ['let [saved (core-fn-call ctx "__current-ns")]
          ['try (emit ctx (node :body))
-          [[(symbol (node :catch-sym))]
+          [[raw]
            ['do (core-fn-call ctx "__set-current-ns!" saved)
-            (emit ctx (node :catch-body))]]]])
+            # bind the catch symbol to the UNWRAPPED value (mirrors the
+            # interpreter), so an interpreted throw's envelope doesn't leak here.
+            ['let [(symbol (node :catch-sym)) (core-fn-call ctx "__unwrap-ex" raw)]
+             (emit ctx (node :catch-body))]]]]])
       (emit ctx (node :body))))
   (if (node :finally)
     ['defer (emit ctx (node :finally)) core]
diff --git a/src/jolt/clojure/java/io.clj b/src/jolt/clojure/java/io.clj
index 1848a54..1f29f23 100644
--- a/src/jolt/clojure/java/io.clj
+++ b/src/jolt/clojure/java/io.clj
@@ -14,6 +14,11 @@
 
 (defn as-file [x] (if (__file? x) x (__make-file x)))
 
+(defn as-url
+  "Coerce `x` to a java.net.URL value (a :jolt/url). Strings are parsed."
+  [x]
+  (if (= :jolt/url (get x :jolt/type)) x (java.net.URL. (str x))))
+
 (defn reader [x]
   (cond
     ;; already a reader (java.io shim or janet file handle) — pass through,
@@ -68,7 +73,23 @@
         (when-not (janet.os/stat parent) (janet.os/mkdir parent))))))
 
 (defn copy
-  "Copy from a path/handle `in` to a path/handle `out`."
-  [in out]
-  (let [content (if (string? in) (slurp in) (janet.file/read in :all))]
-    (if (string? out) (spit out content) (janet.file/write out content))))
+  "Copy from `in` to `out`. A value carrying a truthy `:jolt/output-stream`
+  marker is treated as a java.io OutputStream (write via its .write); a
+  `:jolt/input-stream` source is pumped through its .read. This lets host-shim
+  libraries (e.g. jolt-lang/http-client's byte streams) participate without core
+  knowing their concrete types. Falls back to the original path/handle copy."
+  [in out & opts]
+  (cond
+    (get out :jolt/output-stream)
+    (if (get in :jolt/input-stream)
+      (let [buf (byte-array 8192)]
+        (loop []
+          (let [n (.read in buf 0 8192)]
+            (when (not= -1 n)
+              (.write out buf 0 n)
+              (recur)))))
+      ;; in is a byte-array / string
+      (.write out in))
+    :else
+    (let [content (if (string? in) (slurp in) (janet.file/read in :all))]
+      (if (string? out) (spit out content) (janet.file/write out content)))))
diff --git a/src/jolt/clojure/test.clj b/src/jolt/clojure/test.clj
new file mode 100644
index 0000000..46d722e
--- /dev/null
+++ b/src/jolt/clojure/test.clj
@@ -0,0 +1,171 @@
+; Jolt Standard Library: clojure.test
+;
+; A practical subset of clojure.test for running real test suites under Jolt:
+; deftest / is / testing / are / use-fixtures / run-tests, with class-aware
+; (thrown? Class body) and (thrown-with-msg? Class re body) inside `is`. Class
+; matching is by simple-name (last dotted segment), since Jolt has no JVM class
+; objects — Exception/Throwable match any thrown value.
+;
+; Also exposes the counter/registry API the internal clojure-test-suite harness
+; uses (reset-report!, run-registered, n-pass/n-fail/n-error, failures), so this
+; is a drop-in superset.
+
+(ns clojure.test
+  (:require [clojure.string :as str]))
+
+;; --- state -----------------------------------------------------------------
+
+(def counters (atom {:test 0 :pass 0 :fail 0 :error 0 :fails []}))
+(def jolt-report counters)                ;; alias used by the suite harness
+(def ctx-stack (atom []))
+(def registry (atom []))                ;; [{:name sym :fn thunk}]
+(def once-fixtures (atom []))
+(def each-fixtures (atom []))
+
+(defn reset-report! []
+  (reset! counters {:test 0 :pass 0 :fail 0 :error 0 :fails []})
+  (reset! ctx-stack [])
+  (reset! registry [])
+  (reset! once-fixtures [])
+  (reset! each-fixtures []))
+
+(defn- ctx-str [] (str/join " " @ctx-stack))
+
+(defn inc-pass! [] (swap! counters update :pass inc))
+(defn fail! [form]
+  (let [line (str (ctx-str) (when (seq @ctx-stack) " ") "FAIL: " form)]
+    (swap! counters (fn [r] (-> r (update :fail inc) (update :fails conj line))))
+    (println line)))
+(defn err! [form]
+  (let [line (str (ctx-str) (when (seq @ctx-stack) " ") "ERROR: " form)]
+    (swap! counters (fn [r] (-> r (update :error inc) (update :fails conj line))))
+    (println line)))
+
+(defn n-pass [] (:pass @counters))
+(defn n-fail [] (:fail @counters))
+(defn n-error [] (:error @counters))
+(defn failures [] (:fails @counters))
+
+;; clojure.test/report multimethod — present so suites that add reporting
+;; methods (defmethod clojure.test/report :begin-test-var ...) load. The runner
+;; below does its own console output and doesn't dispatch through it.
+(defmulti report :type)
+(defmethod report :default [_m] nil)
+
+;; --- class matching for thrown? --------------------------------------------
+
+(defn- last-seg [s]
+  (let [s (str s)
+        i (str/last-index-of s ".")]
+    (if i (subs s (inc i)) s)))
+
+(defn class-match?
+  "True if thrown value `e` matches the wanted class simple-name `wanted`.
+  Exception/Throwable match anything."
+  [e wanted]
+  (let [w (last-seg wanted)]
+    (if (or (= w "Exception") (= w "Throwable"))
+      true
+      (let [c (class e)]
+        (and (string? c) (= (last-seg c) w))))))
+
+;; --- assertion macros ------------------------------------------------------
+
+(defn- thrown-form? [form sym]
+  (and (seq? form) (symbol? (first form)) (= sym (name (first form)))))
+
+(defmacro is
+  ([form] `(is ~form nil))
+  ([form msg]
+   (cond
+     ;; (is (thrown? Class body...))
+     (thrown-form? form "thrown?")
+     (let [klass (name (second form))
+           body  (nthrest form 2)]
+       `(try
+          ~@body
+          (clojure.test/fail! (str "expected " '~form " to throw" (when ~msg (str " — " ~msg))))
+          (catch Throwable e#
+            (if (clojure.test/class-match? e# ~klass)
+              (clojure.test/inc-pass!)
+              (clojure.test/fail! (str "expected throw of " ~klass " but got " (clojure.core/class e#)))))))
+
+     ;; (is (thrown-with-msg? Class re body...))
+     (thrown-form? form "thrown-with-msg?")
+     (let [klass (name (second form))
+           re    (nth form 2)
+           body  (nthrest form 3)]
+       `(try
+          ~@body
+          (clojure.test/fail! (str "expected " '~form " to throw"))
+          (catch Throwable e#
+            (let [m# (or (clojure.core/ex-message e#) (str e#))]
+              (if (and (clojure.test/class-match? e# ~klass) (re-find ~re m#))
+                (clojure.test/inc-pass!)
+                (clojure.test/fail! (str "expected throw of " ~klass " matching " ~re " but got " (clojure.core/class e#) ": " m#)))))))
+
+     :else
+     `(try
+        (if ~form
+          (clojure.test/inc-pass!)
+          (clojure.test/fail! (str (pr-str '~form) (when ~msg (str " — " ~msg)))))
+        (catch Throwable e#
+          (clojure.test/err! (str (pr-str '~form) " threw: " (clojure.core/ex-message e#))))))))
+
+(defmacro testing [s & body]
+  `(do
+     (swap! clojure.test/ctx-stack conj ~s)
+     (try
+       (do ~@body)
+       (finally (swap! clojure.test/ctx-stack pop)))))
+
+(defmacro deftest [name & body]
+  `(do
+     (defn ~name [] ~@body)
+     (swap! clojure.test/registry conj {:name '~name :fn ~name})
+     (var ~name)))
+
+(defmacro are [argv expr & data]
+  (let [n (count argv)
+        rows (partition n data)]
+    `(do ~@(map (fn [row]
+                  `(let [~@(interleave argv row)]
+                     (clojure.test/is ~expr)))
+                rows))))
+
+;; --- fixtures + run --------------------------------------------------------
+
+(defn use-fixtures [kind & fns]
+  (cond
+    (= kind :once) (reset! once-fixtures (vec fns))
+    (= kind :each) (reset! each-fixtures (vec fns))))
+
+(defn- wrap-fixtures [fixtures body-fn]
+  (if (empty? fixtures)
+    (body-fn)
+    ((first fixtures) (fn [] (wrap-fixtures (rest fixtures) body-fn)))))
+
+(defn- run-one [t]
+  (swap! counters update :test inc)
+  (wrap-fixtures @each-fixtures
+    (fn []
+      (try
+        ((:fn t))
+        (catch Throwable e
+          (err! (str (:name t) " crashed: " (clojure.core/ex-message e))))))))
+
+(defn run-registered []
+  (doseq [t @registry] (run-one t))
+  nil)
+
+(defn run-tests [& _nses]
+  (wrap-fixtures @once-fixtures (fn [] (run-registered)))
+  (let [r @counters]
+    (println)
+    (println (str "Ran " (:test r) " tests. "
+                  (:pass r) " assertions passed, "
+                  (:fail r) " failures, " (:error r) " errors."))
+    r))
+
+(defn run-test [& _] nil)
+(defn test-var [& _] nil)
diff --git a/src/jolt/core_coll.janet b/src/jolt/core_coll.janet
index a841daa..53fac0f 100644
--- a/src/jolt/core_coll.janet
+++ b/src/jolt/core_coll.janet
@@ -205,6 +205,8 @@
 (defn jolt-call [f & args]
   (cond
     (or (function? f) (cfunction? f)) (apply f args)
+    # a var is callable as its current value (Clojure vars implement IFn)
+    (var? f) (apply jolt-call (var-get f) args)
     (shape-rec? f) (core-get f (get args 0) (get args 1))
     (keyword? f) (core-get (get args 0) f (get args 1))
     (and (struct? f) (= :symbol (f :jolt/type))) (core-get (get args 0) f (get args 1))
@@ -454,12 +456,18 @@
     (and (struct? to) (nil? (get to :jolt/type)))
       (let [acc (array)]
         (each e (pairs to) (array/push acc e))
-        (each item items (array/push acc [(vnth item 0) (vnth item 1)]))
+        # each item is either a [k v] pair OR a map whose entries are merged
+        # (Clojure: (into {} [{:a 1} {:b 2}]) => {:a 1 :b 2})
+        (each item items
+          (if (map-value? item)
+            (each e (map-entries-of item) (array/push acc e))
+            (array/push acc [(vnth item 0) (vnth item 1)])))
         (bulk-map-from-pairs acc))
-    # Other map-likes (sorted maps, deftype records): fold core-assoc.
+    # Other map-likes (sorted maps, deftype records): fold core-conj (handles
+    # both [k v] pairs and map items).
     (or (struct? to) (and (table? to) (get to :jolt/deftype)))
       (do (var result to)
-        (each item items (set result (core-assoc result (vnth item 0) (vnth item 1))))
+        (each item items (set result (core-conj result item)))
         result)
     # Accumulate into a native array and bulk-build the pvec ONCE (pv-from-indexed),
     # instead of an immutable pv-conj per element (each allocating a wrapper +
diff --git a/src/jolt/core_io.janet b/src/jolt/core_io.janet
index 4d0c335..4e824ec 100644
--- a/src/jolt/core_io.janet
+++ b/src/jolt/core_io.janet
@@ -104,6 +104,8 @@
       (let [s (src :s) p (src :pos)]
         (put src :pos (length s))
         (string/slice s p))
+    # a byte-array / buffer body: bytes already in hand, just stringify
+    (buffer? src) (string src)
     (string (slurp src))))
 
 (defn core-spit [path content & opts]
diff --git a/src/jolt/core_print.janet b/src/jolt/core_print.janet
index f819147..388c28c 100644
--- a/src/jolt/core_print.janet
+++ b/src/jolt/core_print.janet
@@ -182,6 +182,9 @@
     (and (struct? v) (= :jolt/inst (v :jolt/type))) (inst->rfc3339 v)
     # a java.io.File renders as its path (Clojure's File.toString)
     (and (table? v) (= :jolt/file (get v :jolt/type))) (get v :path)
+    # (str pattern) -> raw regex source (no #"" delimiters), so libraries that
+    # compose patterns via (re-pattern (str p1 ...)) work (Pattern.toString).
+    (and (table? v) (= :jolt/regex (get v :jolt/type))) (get v :source)
     (= :jolt/namespace (get v :jolt/type)) (ns-display-name v)
     (and (table? v) (= :jolt/var (get v :jolt/type))) (var-display v)
     (number? v) (fmt-number v)
diff --git a/src/jolt/core_refs.janet b/src/jolt/core_refs.janet
index 21bd900..9c218d7 100644
--- a/src/jolt/core_refs.janet
+++ b/src/jolt/core_refs.janet
@@ -124,6 +124,9 @@
 # supers now lives in the Clojure collection tier (no class hierarchy: #{}).
 (defn core-class [x]
   (cond
+    # typed throwables carry their JVM class name (host_net's HTTP/SSL shims):
+    # (class e) -> "java.net.SocketTimeoutException" so (= ClassSym (class e)) holds
+    (and (table? x) (get x :class)) (get x :class)
     (nil? x) nil (number? x) "java.lang.Number" (string? x) "java.lang.String"
     (boolean? x) "java.lang.Boolean" (keyword? x) "clojure.lang.Keyword"
     (function? x) "clojure.lang.IFn" (buffer? x) "[B"
diff --git a/src/jolt/eval_base.janet b/src/jolt/eval_base.janet
index 18632cc..8587a3b 100644
--- a/src/jolt/eval_base.janet
+++ b/src/jolt/eval_base.janet
@@ -140,6 +140,9 @@
   [ctx f args]
   (cond
     (or (function? f) (cfunction? f)) (apply f args)
+    # a var is callable as its current value (Clojure vars implement IFn) —
+    # e.g. (wrap-request #'core/request) threads the var as the base client
+    (var? f) (jolt-invoke ctx (var-get f) args)
     (jolt-transient? f) (transient-lookup f (get args 0) (get args 1))
     # a record shape-rec is callable: IFn impl if it has one, else map-like
     # field access. A plain (non-record) shape-rec is just field access.
diff --git a/src/jolt/eval_runtime.janet b/src/jolt/eval_runtime.janet
index 07b6b06..d5980a6 100644
--- a/src/jolt/eval_runtime.janet
+++ b/src/jolt/eval_runtime.janet
@@ -682,6 +682,12 @@
         false)))
   # instance?: the overlay macro passes the TYPE NAME quoted (class names don't
   # evaluate to values on jolt); the value arg arrives evaluated.
+  # Generic hook so an external host-shim library (e.g. jolt-lang/http-client)
+  # can teach instance? about its own shim types without editing core. Each hook
+  # is (fn [class-name val] -> truthy|nil); consulted when no built-in matches.
+  (var instance-check-hooks @[])
+  (ns-intern core "__register-instance-check!"
+    (fn [f] (array/push instance-check-hooks f) nil))
   (ns-intern core "instance-check"
     (fn [type-sym val]
       (if (record-tag val)
@@ -756,10 +762,21 @@
           "clojure.lang.IPersistentVector" (or (tuple? val) (pvec? val))
           "clojure.lang.IPersistentSet" (set? val)
           "Object" true
-          false))))
+          # no built-in match — consult library-registered instance? hooks
+          (do (var r false)
+              (each h instance-check-hooks
+                (when (h (type-sym :name) val) (set r true) (break)))
+              r)))))
   # Reader / expansion as plain fns: read-string parses one form; macroexpand-1
   # expands a (quoted, already-evaluated) call form once via its macro var.
   (ns-intern core "read-string" (fn [s] (parse-string s)))
+  # Strip the interpreter's {:jolt/type :jolt/exception :value v} throw envelope.
+  # Compiled catch uses this so a caught value matches what the interpreter binds
+  # (interpreted throw wraps; compiled throw raises raw) — keeps (class e) /
+  # ex-message / catch consistent across the compiled⇄interpreted boundary.
+  (ns-intern core "__unwrap-ex"
+    (fn [e] (if (and (or (table? e) (struct? e)) (= :jolt/exception (get e :jolt/type)))
+              (get e :value) e)))
   # The *in* reader family's host seams. __stdin-read-line: one line from real
   # stdin, newline stripped, nil at EOF. __parse-next: one form off a string ->
   # [form rest-of-string], nil when only whitespace remains. *in*, read-line,
diff --git a/src/jolt/reader.janet b/src/jolt/reader.janet
index 4769f1d..bb26d1f 100644
--- a/src/jolt/reader.janet
+++ b/src/jolt/reader.janet
@@ -13,6 +13,7 @@
 
 # Forward declaration for mutual recursion
 (var read-form nil)
+(var read-meta nil)  # forward decl: read-dispatch (#^) calls it before its defn below
 
 # Source-position tracking for the success checker (jolt-fqy). When enabled, the
 # reader records each LIST form's absolute start offset (lists are the forms that
@@ -571,6 +572,7 @@
       (= c 95) (let [[_ new-pos] (read-form s (+ pos 2))]  # #_
                   [{:jolt/type :jolt/skip} new-pos])
       (= c 39) (read-var-quote s pos)      # #'
+      (= c 94) (read-meta s (+ pos 1))     # #^ — deprecated metadata reader macro (= ^)
       (= c 34) (read-regex s pos)          # #"regex
       (= c 35)                             # ## symbolic value: ##Inf ##-Inf ##NaN
         (let [end (read-symbol-name s (+ pos 2) (+ pos 2))
@@ -622,7 +624,7 @@
     (string? meta-form) {:tag meta-form}
     nil))
 
-(defn read-meta [s pos]
+(set read-meta (fn read-meta [s pos]
   # pos is at ^
   (let [[meta-form new-pos] (read-form s (+ pos 1))
         [form new-pos2] (read-form s new-pos)
@@ -636,7 +638,7 @@
       # Non-symbol targets (collections etc.) keep a runtime with-meta form. Use the
       # NORMALIZED metadata map (:kw -> {:kw true}, tag -> {:tag …}); a map-literal
       # meta-form (m is nil) is already a map, so pass it through.
-      [(array (sym "with-meta") form (if m m meta-form)) new-pos2])))
+      [(array (sym "with-meta") form (if m m meta-form)) new-pos2]))))
 
 (defn read-until-newline [s pos]
   (if (or (>= pos (length s)) (= (s pos) 10))
diff --git a/test/spec/clojure-interop-fixes-spec.janet b/test/spec/clojure-interop-fixes-spec.janet
new file mode 100644
index 0000000..3166dd5
--- /dev/null
+++ b/test/spec/clojure-interop-fixes-spec.janet
@@ -0,0 +1,29 @@
+# Specification: Clojure-compat fixes that landed with HTTP-client support
+# (jolt-lang/http-client). All are general language behaviours, exercised here
+# across interpret + compile modes by the harness.
+(use ../support/harness)
+
+(defspec "interop-fixes / deprecated #^ metadata reader"
+  ["#^ type hint on a param"   "\"x\""
+   "(do (defn f1 [#^String s] s) (f1 \"x\"))"]
+  ["#^\"[B\" array hint"        "[1 2]"
+   "(do (defn f2 [#^\"[B\" b] b) (f2 [1 2]))"]
+  ["#^ is equivalent to ^"      "true"
+   "(= (meta (with-meta [] {:tag (quote String)})) {:tag (quote String)})"])
+
+(defspec "interop-fixes / (str pattern) yields raw source"
+  ["str of a regex"            "\"abc\""        "(str #\"abc\")"]
+  ["compose patterns via str"  "true"
+   "(boolean (re-matches (re-pattern (str #\"<\" \"(.*)\" \">\")) \"<hi>\"))"])
+
+(defspec "interop-fixes / into onto a map"
+  ["merges map items"          "true"   "(= {:a 1 :b 2} (into {} [{:a 1} {:b 2}]))"]
+  ["accepts [k v] pairs"       "true"   "(= {:a 1} (into {} [[:a 1]]))"]
+  ["map item onto empty {}"    "true"   "(= {:x 1} (into {} (list {:x 1})))"]
+  ["conj a map onto {}"        "true"   "(= {:a 1} (conj {} {:a 1}))"])
+
+(defspec "interop-fixes / a var is callable as its value"
+  ["call a var directly"       "42"
+   "(do (def vf (fn [x] (inc x))) ((var vf) 41))"]
+  ["var bound as a client fn"  "\"ok\""
+   "(do (def base (fn [_] \"ok\")) (def mw (fn [client] (fn [req] (client req)))) ((mw (var base)) {}))"])