diff --git a/host/chez/rt.ss b/host/chez/rt.ss
index 6179401..9f2c6c8 100644
--- a/host/chez/rt.ss
+++ b/host/chez/rt.ss
@@ -149,3 +149,8 @@
 ;; double/gensym — host-coupled seed natives def-var!'d into clojure.core. Loaded
 ;; LAST because `str` reuses jolt-pr-str (defined just above).
 (load "host/chez/converters.ss")
+
+;; transients (jolt-kl2l): copy-on-write transient collections + persistent disj;
+;; extends get/count/contains? to see through a transient. After collections.ss
+;; (the persistent ops it delegates to).
+(load "host/chez/transients.ss")
diff --git a/host/chez/transients.ss b/host/chez/transients.ss
new file mode 100644
index 0000000..62cda65
--- /dev/null
+++ b/host/chez/transients.ss
@@ -0,0 +1,73 @@
+;; transients (jolt-kl2l) — copy-on-write over the persistent collections.
+;;
+;; A first cut: each transient op rebuilds the persistent collection (no in-place
+;; mutation perf), but the SEMANTICS match — the overlay's transient users (into,
+;; frequencies, group-by) get correct results. get/count/contains? are extended to
+;; see THROUGH a transient to its held collection (frequencies/group-by do
+;; (get tm k) on a transient map). vector? on a transient vector is false (it's a
+;; jolt-transient record, not a pvec), which group-by relies on. Loaded after
+;; collections.ss (the persistent ops it delegates to) and converters.ss.
+
+(define-record-type jolt-transient (fields (mutable coll) (mutable active))
+  (nongenerative jolt-transient-v1))
+
+(define (jolt-transient-new coll) (make-jolt-transient coll #t))
+
+(define (jolt-trans-check t who)
+  (unless (jolt-transient? t) (error #f (string-append who ": not a transient") t))
+  (unless (jolt-transient-active t)
+    (error #f (string-append who ": transient used after persistent!"))))
+
+(define (jolt-persistent! t)
+  (jolt-trans-check t "persistent!")
+  (jolt-transient-active-set! t #f)
+  (jolt-transient-coll t))
+
+(define (jolt-conj! t . xs)
+  (jolt-trans-check t "conj!")
+  (jolt-transient-coll-set! t (apply jolt-conj (jolt-transient-coll t) xs))
+  t)
+(define (jolt-assoc! t k v)
+  (jolt-trans-check t "assoc!")
+  (jolt-transient-coll-set! t (jolt-assoc (jolt-transient-coll t) k v))
+  t)
+(define (jolt-dissoc! t . ks)
+  (jolt-trans-check t "dissoc!")
+  (jolt-transient-coll-set! t (apply jolt-dissoc (jolt-transient-coll t) ks))
+  t)
+(define (jolt-disj! t . xs)
+  (jolt-trans-check t "disj!")
+  (jolt-transient-coll-set! t (apply jolt-disj (jolt-transient-coll t) xs))
+  t)
+(define (jolt-pop! t)
+  (jolt-trans-check t "pop!")
+  (jolt-transient-coll-set! t (jolt-pop (jolt-transient-coll t)))
+  t)
+
+;; persistent disj over sets (pset-disj already exists in collections.ss).
+(define (jolt-disj s . xs)
+  (let loop ((s s) (xs xs)) (if (null? xs) s (loop (pset-disj s (car xs)) (cdr xs)))))
+
+;; get / count / contains? see through a transient. Redefine the native procedures
+;; (captured first) so the existing emit lowerings (jolt-get/jolt-count/
+;; jolt-contains?) unwrap a transient before delegating; non-transients are
+;; untouched.
+(define (jolt-deref-transient x) (if (jolt-transient? x) (jolt-transient-coll x) x))
+(define %prev-jolt-get jolt-get)
+(set! jolt-get
+  (case-lambda
+    ((coll k) (%prev-jolt-get (jolt-deref-transient coll) k))
+    ((coll k d) (%prev-jolt-get (jolt-deref-transient coll) k d))))
+(define %prev-jolt-count jolt-count)
+(set! jolt-count (lambda (coll) (%prev-jolt-count (jolt-deref-transient coll))))
+(define %prev-jolt-contains? jolt-contains?)
+(set! jolt-contains? (lambda (coll k) (%prev-jolt-contains? (jolt-deref-transient coll) k)))
+
+(def-var! "clojure.core" "transient" jolt-transient-new)
+(def-var! "clojure.core" "persistent!" jolt-persistent!)
+(def-var! "clojure.core" "conj!" jolt-conj!)
+(def-var! "clojure.core" "assoc!" jolt-assoc!)
+(def-var! "clojure.core" "dissoc!" jolt-dissoc!)
+(def-var! "clojure.core" "disj!" jolt-disj!)
+(def-var! "clojure.core" "pop!" jolt-pop!)
+(def-var! "clojure.core" "disj" jolt-disj)
diff --git a/test/chez/README.md b/test/chez/README.md
index 2597b98..0134ce2 100644
--- a/test/chez/README.md
+++ b/test/chez/README.md
@@ -104,21 +104,25 @@ corpus case with all of core present, bucketing the result —
     JOLT_CHEZ_PRELUDE_CORPUS=1 janet test/chez/run-corpus-prelude.janet
     JOLT_CORPUS_LIMIT=200 …    (every-Nth stride, fast)
 
-Parity baseline: inc 3j **1220/2497**; inc 3k (converters, jolt-t6cr) **1326/2497**,
-0 NEW divergences (13 allowlisted: dynamic vars `*ns*`/`*clojure-version*`/
-`*unchecked-math*`, var/`*ns*` rendering, class names, eval-order, with-open — all
-deferred Phase-2 / dynamic-var gaps). inc 3k added `host/chez/converters.ss`:
-`str`/`subs`/`vec`/`keyword`/`symbol`/`compare`/`int`/`double`/`gensym` (seed natives,
-matching `core_print.janet`/`core_io.janet` semantics — `str` reuses the printer,
-`compare` is the 3-way port, the symbol no-ns sentinel is `#f` to match emit's
-quoted-symbol lowering so `(= 'x (symbol "x"))` holds).
+Parity baseline: inc 3j **1220/2497**; 3k (converters, jolt-t6cr) **1326**;
+3l (transients, jolt-kl2l) **1382/2497**, 0 NEW divergences (13 allowlisted:
+dynamic vars `*ns*`/`*clojure-version*`/`*unchecked-math*`, var/`*ns*` rendering,
+class names, eval-order, with-open — all deferred Phase-2 / dynamic-var gaps).
+- inc 3k `host/chez/converters.ss`: `str`/`subs`/`vec`/`keyword`/`symbol`/`compare`/
+  `int`/`double`/`gensym` (seed natives — `str` reuses the printer, `compare` is the
+  3-way port, the symbol no-ns sentinel is `#f` to match emit's quoted-symbol
+  lowering so `(= 'x (symbol "x"))` holds).
+- inc 3l `host/chez/transients.ss`: `transient`/`persistent!`/`conj!`/`assoc!`/
+  `dissoc!`/`disj!`/`pop!` as copy-on-write over the persistent collections (correct
+  semantics, no in-place perf), plus persistent `disj`. `get`/`count`/`contains?`
+  are redefined to see THROUGH a transient (frequencies/group-by do `(get tm k)` on a
+  transient map); `vector?` on a transient vector is false, which group-by relies on.
 
 The remaining buckets are the punch-list the next increments chase: ~360 emit-fail
 (genuine host interop — qualified Java/Janet refs, runtime `defmacro`/`eval`, out of
-the analyzer's subset) and ~800 runtime crashes, dominated by core fns calling
-host-coupled seed natives with no Chez shim yet (transients — inc 3l jolt-kl2l),
-plus smaller buckets (`##Inf`/`##NaN` literals → unbound `inf`/`nan`, seq-prim
-transducer arities — inc 3m jolt-q3w8; multimethod dispatch — Phase 2 jolt-9ls5).
+the analyzer's subset) and ~740 runtime crashes, including `##Inf`/`##NaN` literals →
+unbound `inf`/`nan` and seq-prim transducer arities (inc 3m jolt-q3w8), multimethod
+dispatch (Phase 2 jolt-9ls5), and more host-coupled natives without a shim.
 
 Two host shims landed with the prelude. `host/chez/atoms.ss`: atom/deref/swap!/
 reset! (+ compare-and-set!/swap-vals!/reset-vals!) — host-coupled mutable cells the
diff --git a/test/chez/emit-test.janet b/test/chez/emit-test.janet
index 19e62dc..f966cf2 100644
--- a/test/chez/emit-test.janet
+++ b/test/chez/emit-test.janet
@@ -427,6 +427,46 @@
     (ok (string "conv: " src) (and (= code 0) (= out want))
         (string "chez=" out " janet=" want " | " err))))
 
+# 3q) transients (jolt-kl2l): transient/persistent!/conj!/assoc!/dissoc!/disj!/
+#   pop! as copy-on-write over the persistent collections (host/chez/transients.ss),
+#   plus persistent disj. get/count/contains? see THROUGH a transient (frequencies
+#   and group-by do (get tm k) on a transient map). vector? on a transient vector
+#   is false. Map/set print order isn't canonical, so assert via get/count/contains?.
+(each src ["(persistent! (conj! (transient []) 1 2 3))"
+           "(count (conj! (conj! (transient []) 1) 2))"
+           "(get (assoc! (transient {}) :a 5) :a)"
+           "(get (transient {:x 9}) :x)"
+           "(contains? (assoc! (transient {}) :k 1) :k)"
+           "(count (persistent! (dissoc! (assoc! (assoc! (transient {}) :a 1) :b 2) :a)))"
+           "(vector? (transient []))"
+           "(persistent! (pop! (conj! (transient [1 2 3]) 4)))"
+           "(count (persistent! (disj! (transient #{1 2 3}) 2)))"
+           "(contains? (disj #{1 2 3} 2) 2)"
+           "(count (disj #{1 2 3} 2))"]
+  (let [[code out err] (run-prelude src) want (cli-oracle src)]
+    (ok (string "transient: " src) (and (= code 0) (= out want))
+        (string "chez=" out " janet=" want " | " err))))
+
+# frequencies/group-by/into are OVERLAY fns built on transients — they need the
+# full assembled prelude, so exercise them end-to-end through the jolt-chez -e
+# binary (which loads rt.ss + the prelude). This doubles as a smoke test of the
+# assembled -e-capable jolt-chez itself.
+(defn run-jolt-chez [src]
+  (def proc (os/spawn ["bin/jolt-chez" "-e" src] :p {:out :pipe :err :pipe}))
+  (def out (ev/read (proc :out) 0x100000))
+  (def err (ev/read (proc :err) 0x100000))
+  [(os/proc-wait proc) (string/trim (if out (string out) "")) (string/trim (if err (string err) ""))])
+(when (os/stat "bin/jolt-chez")
+  (each src ["(get (frequencies [1 1 2 3 3 3]) 3)"
+             "(get (frequencies [:a :b :a]) :a)"
+             "(get (group-by even? [1 2 3 4 5]) true)"
+             "(count (get (group-by even? (range 10)) false))"
+             "(into [] (range 5))"
+             "(count (into #{} [1 2 2 3]))"]
+    (let [[code out err] (run-jolt-chez src) want (cli-oracle src)]
+      (ok (string "jolt-chez -e: " src) (and (= code 0) (= out want))
+          (string "chez=" out " janet=" want " | " err)))))
+
 # 4) perf signal: emitted fib(30) in-Scheme timing (excludes Chez startup), to
 #    track against the spike ceiling (hand-Scheme fib ~5ms). Informational — the
 #    jolt-truthy? wrapper (~3x) and flonum modeling are known Phase-4 levers.
diff --git a/test/chez/run-corpus-prelude.janet b/test/chez/run-corpus-prelude.janet
index ef6eac1..4c87f71 100644
--- a/test/chez/run-corpus-prelude.janet
+++ b/test/chez/run-corpus-prelude.janet
@@ -129,9 +129,9 @@
 # Regression floor (inc 3j baseline): raise as runtime gaps close, like the probe
 # reach-floor and the suite baseline. The gate fails if parity drops below it, or
 # on any NEW (un-allowlisted) divergence — a real Chez correctness regression.
-# Full-corpus baseline: inc 3j 1220/2497; inc 3k (converters) 1326. Strided runs
-# scale the floor down.
-(def base-floor (scan-number (or (os/getenv "JOLT_CHEZ_PRELUDE_FLOOR") "1326")))
+# Full-corpus baseline: inc 3j 1220/2497; 3k (converters) 1326; 3l (transients)
+# 1382. Strided runs scale the floor down.
+(def base-floor (scan-number (or (os/getenv "JOLT_CHEZ_PRELUDE_FLOOR") "1382")))
 (def floor (if (os/getenv "JOLT_CORPUS_LIMIT") 0 base-floor))
 (when (or (> (length diverged) 0) (< pass floor))
   (printf "REGRESSION: pass %d < floor %d or %d new divergence(s)" pass floor (length diverged)))