diff --git a/jolt-core/clojure/core/40-lazy.clj b/jolt-core/clojure/core/40-lazy.clj
index 4b981b7..655e4be 100644
--- a/jolt-core/clojure/core/40-lazy.clj
+++ b/jolt-core/clojure/core/40-lazy.clj
@@ -3,17 +3,26 @@
 ;;
 ;; Each fn ported from CLJS core.cljs, stripped of chunked-seq branches.
 
-;; --- distinct ---
-(defn distinct [coll]
-  (let [step (fn step [xs seen]
-               (lazy-seq
-                 ((fn [[f :as xs] seen]
-                    (when-let [s (seq xs)]
-                      (if (contains? seen f)
-                        (recur (rest s) seen)
-                        (cons f (step (rest s) (conj seen f))))))
-                   xs seen)))]
-    (step coll #{})))
+;; --- distinct --- (transducer + lazy collection arity; value-based dedup)
+(defn distinct
+  ([]
+   (fn [rf]
+     (let [seen (volatile! #{})]
+       (fn ([] (rf)) ([result] (rf result))
+         ([result input]
+          (if (contains? @seen input)
+            result
+            (do (vswap! seen conj input) (rf result input))))))))
+  ([coll]
+   (let [step (fn step [xs seen]
+                (lazy-seq
+                  ((fn [[f :as xs] seen]
+                     (when-let [s (seq xs)]
+                       (if (contains? seen f)
+                         (recur (rest s) seen)
+                         (cons f (step (rest s) (conj seen f))))))
+                    xs seen)))]
+     (step coll #{}))))
 
 
 ;; --- keep ---
@@ -76,7 +85,9 @@
         (cstep 0)))
     ()))
 
-;; --- repeatedly ---
+;; --- repeatedly --- ((f) throws on a non-fn; (take n …) throws on a non-number
+;; count — both now enforced in the seed (jolt-call / core-take), so the canonical
+;; CLJ form matches the repeatedly.cljc exception cases.)
 (defn repeatedly
   ([f] (lazy-seq (cons (f) (repeatedly f))))
   ([n f] (take n (repeatedly f))))
@@ -91,10 +102,39 @@
   (lazy-seq (cons x (iterate f (f x)))))
 
 
-;; --- partition-all ---
+;; --- partition-all --- (transducer + [n coll] + [n step coll])
+;; The collection arities realize EXACTLY n per chunk via a first/rest loop and
+;; continue from the advanced cursor (not a re-drop / nthrest), so they realize
+;; minimally — matching the Janet pstep the §6.3 laziness counters were written
+;; against. (A take/nthrest form is correct but over-realizes.)
 (defn partition-all
-  ([n coll] (partition-all n n coll))
+  ([n]
+   (fn [rf]
+     (let [a (volatile! [])]
+       (fn
+         ([] (rf))
+         ([result]
+          (let [result (if (zero? (count @a))
+                         result
+                         (let [v @a] (vreset! a []) (unreduced (rf result v))))]
+            (rf result)))
+         ([result input]
+          (vswap! a conj input)
+          (if (= n (count @a))
+            (let [v @a] (vreset! a []) (rf result v))
+            result))))))
+  ([n coll]
+   (letfn [(go [s]
+             (lazy-seq
+               (when (seq s)
+                 (loop [i 0 chunk [] cur s]
+                   (if (and (< i n) (seq cur))
+                     (recur (inc i) (conj chunk (first cur)) (rest cur))
+                     (cons chunk (go cur)))))))]
+     (go coll)))
   ([n step coll]
-   (lazy-seq
-    (when-let [s (seq coll)]
-      (cons (take n s) (partition-all n step (nthrest coll step)))))))
+   (letfn [(go [s]
+             (lazy-seq
+               (when (seq s)
+                 (cons (take n s) (go (nthrest s step))))))]
+     (go coll))))
diff --git a/jolt-core/jolt/analyzer.clj b/jolt-core/jolt/analyzer.clj
index d5d016d..d820318 100644
--- a/jolt-core/jolt/analyzer.clj
+++ b/jolt-core/jolt/analyzer.clj
@@ -15,12 +15,12 @@
   declared — the bootstrap compiles forward refs through var cells, but keeping
   them to one keeps the compiled namespace simple."
   (:require [jolt.ir :refer [const local var-ref host-ref if-node do-node invoke
-                             def-node let-node fn-node vector-node map-node
+                             def-node let-node fn-node vector-node map-node set-node
                              quote-node throw-node]]
             [jolt.host :refer [form-sym? form-sym-name form-sym-ns form-list?
                                form-vec? form-map? form-set? form-char?
                                form-literal? form-elements form-vec-items
-                               form-map-pairs form-special? compile-ns
+                               form-map-pairs form-set-items form-special? compile-ns
                                form-macro? form-expand-1 resolve-global
                                form-sym-meta host-intern! form-syntax-quote-lower]]))
 
@@ -207,6 +207,6 @@
      (form-map? form) (map-node (mapv (fn [p] [(analyze ctx (first p) env)
                                               (analyze ctx (second p) env)])
                                      (form-map-pairs form)))
-     (form-set? form) (uncompilable "set literal")
+     (form-set? form) (set-node (mapv #(analyze ctx % env) (form-set-items form)))
      (form-list? form) (analyze-list ctx form env)
      :else (uncompilable "unsupported form"))))
diff --git a/src/jolt/api.janet b/src/jolt/api.janet
index e3af642..b97fa28 100644
--- a/src/jolt/api.janet
+++ b/src/jolt/api.janet
@@ -53,7 +53,8 @@
    {:ns "clojure.core.00-kernel" :kernel true}
    {:ns "clojure.core.10-seq"    :kernel false}
    {:ns "clojure.core.20-coll"   :kernel false}
-   {:ns "clojure.core.30-macros" :kernel false}])
+   {:ns "clojure.core.30-macros" :kernel false}
+   {:ns "clojure.core.40-lazy"   :kernel false}])
 
 (defn- eval-overlay-source [ctx src]
   (var s src)
diff --git a/src/jolt/backend.janet b/src/jolt/backend.janet
index d1d1961..fe797cb 100644
--- a/src/jolt/backend.janet
+++ b/src/jolt/backend.janet
@@ -230,6 +230,12 @@
     (array/push args (emit ctx (in p 1))))
   (tuple/slice args))
 
+# A set literal: build (make-phs e1 e2 …) so each element is evaluated at runtime
+# then the persistent set is constructed — mirrors compiler.janet's emit-set-expr.
+(defn- emit-set [ctx node]
+  (def items (map |(emit ctx $) (vview (node :items))))
+  (tuple/slice (array/concat @[phm/make-phs] items)))
+
 (set emit
   (fn emit [ctx raw]
     (def node (norm-node raw))
@@ -259,6 +265,7 @@
       :invoke (emit-invoke ctx node)
       :vector (emit-vector ctx node)
       :map (emit-map ctx node)
+      :set (emit-set ctx node)
       :quote ['quote (node :form)]
       (error (string "backend: unhandled op " (node :op))))))
 
diff --git a/src/jolt/compiler.janet b/src/jolt/compiler.janet
index d700472..abd27ca 100644
--- a/src/jolt/compiler.janet
+++ b/src/jolt/compiler.janet
@@ -163,7 +163,6 @@
              "find-ns" "all-ns" "the-ns" "find-var" "intern" "resolve"
              "ns-resolve" "ns-aliases" "ns-imports" "ns-interns"
              "alter-var-root" "alter-meta!" "reset-meta!" "locking" "new"
-             "disj" "set?"
              # Definitional/host macros that mutate context or build runtime
              # values the emitter doesn't model.
              "defrecord" "defprotocol" "definterface" "reify" "proxy"
diff --git a/src/jolt/core.janet b/src/jolt/core.janet
index 4301997..821ebea 100644
--- a/src/jolt/core.janet
+++ b/src/jolt/core.janet
@@ -508,7 +508,10 @@
         (if (and (number? k) (= k (math/floor k)) (>= k 0) (< k (length f)))
           (in f k)
           (error (string "Index " k " out of bounds for vector of length " (length f)))))
-    (or (struct? f) (and (table? f) (get f :jolt/deftype)))
+    # Map literal (struct with no :jolt/type marker) or a record: callable as a
+    # key lookup. A TAGGED struct (char/etc.) is NOT a fn — symbols are handled
+    # above; everything else with a :jolt/type falls through to the error.
+    (or (and (struct? f) (nil? (get f :jolt/type))) (and (table? f) (get f :jolt/deftype)))
       (let [v (get f (get args 0) :jolt/not-found)]
         (if (= v :jolt/not-found) (get args 1) v))
     (error (string "Cannot call " (type f) " as a function"))))
@@ -804,9 +807,7 @@
   (fn [rf] (fn [& a] (case (length a) 0 (rf) 1 (rf (a 0))
                        (if (truthy? (pred (a 1))) (rf (a 0) (a 1)) (a 0))))))
 (defn td-remove [pred] (td-filter (fn [x] (not (pred x)))))
-(defn td-keep [f]
-  (fn [rf] (fn [& a] (case (length a) 0 (rf) 1 (rf (a 0))
-                       (let [v (f (a 1))] (if (nil? v) (a 0) (rf (a 0) v)))))))
+# td-keep removed: keep (incl its transducer arity) lives in core/40-lazy.clj.
 (defn td-take [n]
   (fn [rf]
     (var left n)
@@ -829,31 +830,11 @@
     (fn [& a] (case (length a) 0 (rf) 1 (rf (a 0))
                 (do (when (and dropping (not (truthy? (pred (a 1))))) (set dropping false))
                   (if dropping (a 0) (rf (a 0) (a 1))))))))
-(defn td-map-indexed [f]
-  (fn [rf]
-    (var i -1)
-    (fn [& a] (case (length a) 0 (rf) 1 (rf (a 0)) (do (++ i) (rf (a 0) (f i (a 1))))))))
+# td-map-indexed removed: map-indexed (incl transducer arity) lives in core/40-lazy.clj.
 
 # Stateful windowing transducers. The 1-arg (completion) arity flushes a partial
 # trailing window before delegating to rf's completion; matches Clojure.
-(defn td-partition-all [n]
-  (fn [rf]
-    (var buf @[])
-    (fn [& a]
-      (case (length a)
-        0 (rf)
-        1 (let [result (if (= 0 (length buf)) (a 0)
-                         (let [v (tuple/slice (tuple ;buf))]
-                           (set buf @[])
-                           (core-unreduced (rf (a 0) v))))]
-            (rf result))
-        (do
-          (array/push buf (a 1))
-          (if (= n (length buf))
-            (let [v (tuple/slice (tuple ;buf))]
-              (set buf @[])
-              (rf (a 0) v))
-            (a 0)))))))
+# td-partition-all removed: partition-all (incl transducer arity) lives in core/40-lazy.clj.
 
 # partition-by's transducer arity lives with its (lazy) collection arity in the
 # overlay (10-seq tier), written in Clojure with volatiles.
@@ -1113,6 +1094,9 @@
       (error "Wrong number of args passed to: reduce"))))
 
 (defn core-take [n & rest]
+ # n is a count — reject non-numbers (e.g. a char/string) like Clojure, rather
+ # than letting Janet's >= silently compare mixed types.
+ (unless (number? n) (error (string "take: n must be a number, got " (type n))))
  (if (= 0 (length rest)) (td-take n)
   (let [coll (in rest 0)]
     # Option A: lazy take (returns a seq, not a vector, even over a vector).
@@ -1342,22 +1326,7 @@
           (sort-by keyfn arr))
         (tuple/slice (tuple ;arr))))))
 
-(defn core-distinct [coll]
-  # Option A: always lazy. seen-set is captured once and shared across the chain.
-  (let [seen @{}]
-    (defn dstep [c]
-      (fn []
-        (var cur c) (var found false) (var result nil)
-        (while (and (not found) (not (seq-done? cur)))
-          (let [x (core-first cur)]
-            (set cur (core-rest cur))
-            (when (nil? (seen x))
-              (put seen x true)
-              (set found true)
-              (set result x))))
-        (if found @[result (dstep cur)] nil)))
-    (make-lazy-seq (dstep (lazy-from coll)))))
-
+# distinct now lives in the Clojure lazy tier (core/40-lazy.clj).
 # group-by / frequencies now live in the Clojure collection tier
 # (core/20-coll.clj).
 
@@ -1384,72 +1353,13 @@
               nil)))))
     (make-lazy-seq (pstep (lazy-from coll)))))
 
-(defn core-partition-by [f coll]
-  (def f (as-fn f))
-  (var result @[])
-  (var part @[])
-  (var last-k nil)
-  (each x (realize-for-iteration coll)
-    (let [k (f x)]
-      (if (and last-k (deep= k last-k))
-        (array/push part x)
-        (do
-          (if (> (length part) 0) (array/push result (tuple/slice (tuple ;part))))
-          (set part @[x])
-          (set last-k k)))))
-  (if (> (length part) 0) (array/push result (tuple/slice (tuple ;part))))
-  result)
+# partition-by now lives in the Clojure seq tier (core/10-seq.clj).
 
-(defn core-partition-all [n & rest]
- (if (= 0 (length rest)) (td-partition-all n)
-  (let [coll (in rest 0)]
-  # Option A: always lazy.
-  (defn pstep [c]
-    (fn []
-      (if (seq-done? c) nil
-        (do
-          (var part @[]) (var cur c) (var i 0)
-          (while (and (< i n) (not (seq-done? cur)))
-            (array/push part (core-first cur))
-            (set cur (core-rest cur))
-            (++ i))
-          @[(tuple/slice (tuple ;part)) (pstep cur)]))))
-  (make-lazy-seq (pstep (lazy-from coll))))))
+# partition-all now lives in the Clojure lazy tier (core/40-lazy.clj).
 
 
-(defn core-keep-indexed [f coll]
-  (def f (as-fn f))
-  # Option A: always lazy.
-  (defn kstep [c i]
-    (fn []
-      (var cur c) (var idx i) (var found false) (var result nil)
-      (while (and (not found) (not (seq-done? cur)))
-        (let [v (f idx (core-first cur))]
-          (++ idx)
-          (set cur (core-rest cur))
-          (when (not (nil? v))
-            (set found true)
-            (set result v))))
-      (if found @[result (kstep cur idx)] nil)))
-  (make-lazy-seq (kstep (lazy-from coll) 0)))
-
-(defn core-map-indexed [f & rest]
-  (if (= 0 (length rest)) (td-map-indexed f)
-    (let [coll (in rest 0)]
-      # Option A: always lazy.
-      (defn mstep [c i]
-        (fn []
-          (if (seq-done? c) nil
-            @[(f i (core-first c)) (mstep (core-rest c) (+ i 1))])))
-      (make-lazy-seq (mstep (lazy-from coll) 0)))))
-
-(defn core-cycle [coll]
-  (let [c (realize-for-iteration coll)]
-    (if (= 0 (length c))
-      (make-lazy-seq (fn [] nil))
-      (do
-        (defn cstep [i] (fn [] @[(in c (% i (length c))) (cstep (+ i 1))]))
-        (make-lazy-seq (cstep 0))))))
+# keep-indexed / map-indexed / cycle now live in the Clojure lazy tier
+# (core/40-lazy.clj).
 
 # reduce-kv now lives in the Clojure collection tier (core/20-coll.clj).
 
@@ -1495,30 +1405,9 @@
           (+= i step))
         (tuple/slice (tuple ;result))))))
 
-(defn core-repeat
-  "(repeat x) -> infinite lazy seq of x; (repeat n x) -> n copies of x."
-  [a & rest]
-  (if (= 0 (length rest))
-    (do (defn rstep [] (fn [] @[a (rstep)])) (make-lazy-seq (rstep)))
-    (let [n a x (in rest 0)]
-      (var result @[]) (var i 0)
-      (while (< i n) (array/push result x) (++ i))
-      result)))
+# repeat / iterate now live in the Clojure lazy tier (core/40-lazy.clj).
 
-(defn core-iterate [f x]
-  "Lazy infinite sequence x, (f x), (f (f x)), ..."
-  (defn istep [v] (fn [] @[v (istep (f v))]))
-  (make-lazy-seq (istep x)))
-
-(defn core-repeatedly
-  "(repeatedly f) -> infinite lazy seq of (f) calls; (repeatedly n f) -> n calls."
-  [a & rest]
-  (if (= 0 (length rest))
-    (do (defn rstep [] (fn [] @[(a) (rstep)])) (make-lazy-seq (rstep)))
-    (let [n a f (in rest 0)]
-      (var result @[]) (var i 0)
-      (while (< i n) (array/push result (f)) (++ i))
-      result)))
+# repeatedly now lives in the Clojure lazy tier (core/40-lazy.clj).
 
 # ============================================================
 # Higher-order functions
@@ -2408,26 +2297,7 @@
               @[(core-first c) (istep (core-rest c) true)]))))
       (make-lazy-seq (istep (lazy-from coll) false)))))
 
-(defn core-keep
-  "(keep f coll) — (f x) for each x, dropping nils. (keep f) is a transducer."
-  [f & rest]
-  (def f (as-fn f))
-  (if (= 0 (length rest))
-    (td-keep f)
-    (let [coll (in rest 0)]
-      # Option A: always lazy.
-      (defn kstep [c]
-        (fn []
-          (var cur c) (var found false) (var result nil)
-          (while (and (not found) (not (seq-done? cur)))
-            (let [v (f (core-first cur))]
-              (set cur (core-rest cur))
-              (when (not (nil? v))
-                (set found true)
-                (set result v))))
-          (if found @[result (kstep cur)] nil)))
-      (make-lazy-seq (kstep (lazy-from coll))))))
-
+# keep now lives in the Clojure lazy tier (core/40-lazy.clj).
 
 (defn core-empty [coll]
   (cond
@@ -2517,14 +2387,7 @@
 # Iterator/enumeration seqs — Jolt has no Java iterators, so adapt to plain seq.
 (defn core-enumeration-seq [x] (core-seq x))
 (defn core-iterator-seq [x] (core-seq x))
-(defn core-xml-seq [root]
-  (def out @[])
-  (defn walk [n]
-    (array/push out n)
-    (when (and (core-map? n) (core-contains? n :content))
-      (each c (realize-for-iteration (core-get n :content)) (walk c))))
-  (walk root)
-  (tuple ;out))
+# xml-seq now lives in the Clojure collection tier (core/20-coll.clj).
 (defn core-line-seq [rdr]
   (if (string? rdr) (core-seq (string/split "\n" rdr)) nil))
 (defn core-re-matcher [re s] @{:jolt/type :jolt/matcher :re re :s s :pos 0})
@@ -2866,10 +2729,6 @@
     "get-in" core-get-in
     "contains?" core-contains?
     "count" core-count
-    "partition-all" core-partition-all
-    "keep-indexed" core-keep-indexed
-    "map-indexed" core-map-indexed
-    "cycle" core-cycle
     "pop" core-pop
     "trampoline" core-trampoline
     "format" core-format
@@ -2952,7 +2811,6 @@
     "random-uuid" core-random-uuid
     "interpose" core-interpose
     "mapcat" core-mapcat
-    "keep" core-keep
     "find" core-find
     "transduce" core-transduce
     "sequence" core-sequence
@@ -2990,13 +2848,8 @@
     "nth" core-nth
     "sort" core-sort
     "sort-by" core-sort-by
-    "distinct" core-distinct
     "partition" core-partition
-    "partition-by" core-partition-by
     "range" core-range
-    "repeat" core-repeat
-    "iterate" core-iterate
-    "repeatedly" core-repeatedly
     "identity" core-identity
     "constantly" core-constantly
     "complement" core-complement
@@ -3103,7 +2956,6 @@
     "test" core-test
     "enumeration-seq" core-enumeration-seq
     "iterator-seq" core-iterator-seq
-    "xml-seq" core-xml-seq
     "line-seq" core-line-seq
     "re-matcher" core-re-matcher
     "bean" core-bean
diff --git a/src/jolt/evaluator.janet b/src/jolt/evaluator.janet
index 4c8bcc9..32ce62c 100644
--- a/src/jolt/evaluator.janet
+++ b/src/jolt/evaluator.janet
@@ -26,7 +26,6 @@
       (= name "var-get") (= name "var-set") (= name "var?")
       (= name "alter-var-root") (= name "find-var") (= name "intern")
       (= name "alter-meta!") (= name "reset-meta!")
-      (= name "disj") (= name "set?")
       (= name "satisfies?")
       (= name "protocol-dispatch") (= name "register-method") (= name "make-reified")
       (= name "prefer-method") (= name "remove-method") (= name "remove-all-methods")
@@ -116,7 +115,9 @@
         (if (and (number? k) (= k (math/floor k)) (>= k 0) (< k (length f)))
           (in f k)
           (error (string "Index " k " out of bounds for vector of length " (length f)))))
-    (struct? f)
+    # Map literal only (struct with no :jolt/type). A tagged struct (char/etc.)
+    # is not callable — symbols are handled above; chars fall through to the error.
+    (and (struct? f) (nil? (get f :jolt/type)))
       (let [v (get f (get args 0) :jolt/not-found)]
         (if (= v :jolt/not-found) (get args 1) v))
     (and (table? f) (get f :jolt/deftype))
@@ -1140,12 +1141,8 @@
                    val (eval-form ctx bindings (in form 3))
                    ns (ctx-find-ns ctx (if (struct? ns-name) (ns-name :name) ns-name))]
                (ns-intern ns (if (struct? sym-name) (sym-name :name) sym-name) val))
-    "disj" (let [s (eval-form ctx bindings (in form 1))
-                 ks (map |(eval-form ctx bindings $) (tuple/slice form 2))]
-             (if (set? s)
-               (apply phs-disj s ks)
-               (error "disj expects a set")))
-    "set?" (set? (eval-form ctx bindings (in form 1)))
+    # set?/disj are plain clojure.core fns now (core-set?/core-disj) — no longer
+    # special-cased here, the analyzer, or compiler.janet (jolt-g3h).
     "protocol-dispatch" (let [proto-sym (in form 1)
                                method-sym (in form 2)
                                obj (eval-form ctx bindings (in form 3))
diff --git a/src/jolt/host_iface.janet b/src/jolt/host_iface.janet
index ff1b37e..d2dbd9e 100644
--- a/src/jolt/host_iface.janet
+++ b/src/jolt/host_iface.janet
@@ -74,7 +74,7 @@
              "defmacro" "fn*" "let*" "loop*" "recur" "throw" "try" "set!" "var"
              "locking" "eval" "instance?" "defmulti" "defmethod" "deftype" "new"
              "." "var-get" "var-set" "var?" "alter-var-root" "find-var" "intern"
-             "alter-meta!" "reset-meta!" "disj" "set?" "satisfies?"
+             "alter-meta!" "reset-meta!" "satisfies?"
              "protocol-dispatch" "register-method" "make-reified" "prefer-method"
              "remove-method" "remove-all-methods" "get-method" "methods"
              # ns-management forms dispatched by the interpreter (not core vars)
diff --git a/test/integration/clojure-test-suite-test.janet b/test/integration/clojure-test-suite-test.janet
index 07bf4ba..e7586d1 100644
--- a/test/integration/clojure-test-suite-test.janet
+++ b/test/integration/clojure-test-suite-test.janet
@@ -38,9 +38,14 @@
 # lazy-from throws on non-seqable like Clojure) recovered + extended the suite.
 # clean files 45 -> 66 (Option A makes seq?/vector? results match Clojure across
 # many cross-dialect files). Stable across runs.
-(def baseline-pass 3981)
+# Raised 3981 -> 4004 migrating 7 lazy seq fns to the Clojure overlay (40-lazy
+# tier): the canonical CLJ versions add coverage (e.g. distinct value-equality).
+# Raised 4004 -> 4034 / clean 66 -> 67 porting partition-all + repeatedly to the
+# overlay, which required fixing two leniencies (a char is not callable; take
+# validates its count) — correct beyond those fns, so the suite rose broadly.
+(def baseline-pass 4034)
 # A file is "clean" when it ran with zero failures AND zero errors.
-(def baseline-clean-files 66)
+(def baseline-clean-files 67)
 # Per-file wall-clock budget (seconds). Normal files finish in well under 1s, so
 # this normally only fires on genuinely-infinite-sequence hangs. It's an env var
 # (JOLT_SUITE_TIMEOUT) so CI — whose runners are slower than a dev machine — can
diff --git a/test/integration/conformance-test.janet b/test/integration/conformance-test.janet
index 81fa206..f400793 100644
--- a/test/integration/conformance-test.janet
+++ b/test/integration/conformance-test.janet
@@ -50,6 +50,18 @@
    ["map as fn default" "99" "({:a 1} :z 99)"]
    ["set as fn"     "2"   "(#{1 2 3} 2)"]
    ["set as fn miss" "nil" "(#{1 2 3} 9)"]
+   # set literals compile (Stage 1 Task 1): computed elements are each evaluated
+   # then the persistent set is built, matching the interpreter.
+   ["set literal computed" "true" "(= #{1 2} #{(inc 0) 2})"]
+   ["empty set literal"    "true" "(empty? #{})"]
+   ["set literal count"    "3"    "(count #{1 2 3})"]
+   ["set literal in let"   "true" "(let [x 5] (= #{5 6} #{x (inc x)}))"]
+   # set?/disj compile as plain fns now (jolt-g3h), not special forms
+   ["set? true"   "true"      "(set? #{1 2 3})"]
+   ["set? false"  "false"     "(set? [1 2])"]
+   ["disj one"    "#{1 3}"    "(disj #{1 2 3} 2)"]
+   ["disj many"   "#{1}"      "(disj #{1 2 3} 2 3)"]
+   ["disj absent" "#{1 2}"    "(disj #{1 2} 5)"]
    ["keyword as fn" "1"   "(:a {:a 1})"]
    ["map fn over coll" "(quote (1 3))" "(map {:a 1 :b 3} [:a :b])"]
 
diff --git a/test/integration/fallback-zero-test.janet b/test/integration/fallback-zero-test.janet
new file mode 100644
index 0000000..c5bcc50
--- /dev/null
+++ b/test/integration/fallback-zero-test.janet
@@ -0,0 +1,66 @@
+# Fallback-zero verification (Stage 1 Task 3).
+#
+# self-host-test.janet checks observable RESULTS but not WHICH path ran — a form
+# that silently fell back to the interpreter still "passes" there. This harness
+# checks the path: it runs the portable analyzer (jolt.analyzer/analyze, via
+# backend/analyze-form) on a corpus of NON-STATEFUL forms and asserts NONE raise
+# :jolt/uncompilable — i.e. the self-hosted analyzer actually COMPILED them.
+#
+# As analyzer↔compiler.janet parity grows (Stage 1), move forms from the
+# "intentional fallback" sanity list into the must-compile corpus. The day the
+# fallback set equals the frozen intentional stateful set, the Janet bootstrap
+# compiler is retireable.
+#
+# Mechanism: backend/analyze-form throws (a "jolt/uncompilable: …" string) for a
+# punted form; (protect …) turns that into [false msg]. [true ir] == compiled.
+
+(import ../../src/jolt/backend :as backend)
+(use ../../src/jolt/api)
+(use ../../src/jolt/reader)
+
+(def ctx (init))
+
+(defn- analyzes? [s]
+  # true if the analyzer produced IR (compiled), false if it punted/uncompilable.
+  (def r (protect (backend/analyze-form ctx (parse-string s))))
+  (and (r 0) true))
+
+# --- Must compile: pure, non-stateful value production. NONE may punt. ---
+(def must-compile
+  [# set literals (Task 1)
+   "#{1 2 3}" "#{}" "#{:a :b :c}" "#{(inc 0) 2}" "(conj #{1 2} 3)"
+   "[#{1 2} {:s #{3}}]" "(let [x 5] #{x (inc x)})"
+   # other literals
+   "[1 2 3]" "{:a 1 :b 2}" "{:k (inc 0)}" "[[1] [2 3]]" "42" ":kw" "\"str\""
+   # control flow + binding
+   "(+ 1 2)" "(if true 1 2)" "(do 1 2 3)" "(let [a 1 b 2] (+ a b))"
+   "(fn [x] (* x x))" "(fn ([a] a) ([a b] (+ a b)))"
+   "(loop [i 0] (if (< i 3) (recur (inc i)) i))"
+   "(quote (a b c))" "(throw (ex-info \"x\" {}))"
+   "(try (inc 1) (catch :default e e))"
+   # def + calls into core
+   "(def answer 42)" "(map inc [1 2 3])" "(reduce + 0 [1 2 3])"
+   "(get {:a 1} :a)" "(vec (range 5))"
+   # set?/disj are plain fns now, not special forms (jolt-g3h)
+   "(set? #{1 2})" "(disj #{1 2 3} 2)"])
+
+# --- Intentional fallback (sanity sample): these SHOULD punt to the interpreter.
+# Not the frozen set (that's Task 2) — just a few to confirm the boundary holds
+# in the punt direction so the harness can't pass by compiling everything.
+(def must-punt
+  ["(ns foo.bar)" "(defmacro m [x] x)" "(require (quote [clojure.string]))"
+   "(set! *warn-on-reflection* true)" "(letfn [(f [n] (g n)) (g [n] (f n))] (f 1))"])
+
+(var fails @[])
+(each s must-compile
+  (unless (analyzes? s) (array/push fails (string "FALLBACK (should compile): " s))))
+(each s must-punt
+  (when (analyzes? s) (array/push fails (string "COMPILED (should punt): " s))))
+
+(printf "fallback-zero: %d must-compile + %d must-punt — %d failures"
+        (length must-compile) (length must-punt) (length fails))
+(when (> (length fails) 0)
+  (print "\nFailures:")
+  (each f fails (printf "  %s" f))
+  (os/exit 1))
+(print "fallback-zero: OK (analyzer compiled the full non-stateful corpus)")