diff --git a/CHANGES.md b/CHANGES.md
index 9c9e0bf2c3..3ac33f15d4 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -24,11 +24,12 @@
 - Fix text editor v1 focus [Taiga #13961](https://tree.taiga.io/project/penpot/issue/13961)
 
 
-## 2.14.3 (Unreleased)
+## 2.14.3
 
 ### :sparkles: New features & Enhancements
 
 - Add webp export format to plugin types [Github #8870](https://github.com/penpot/penpot/pull/8870)
+- Use shared singleton containers for React portals to reduce DOM growth [Github #8957](https://github.com/penpot/penpot/pull/8957)
 
 ### :bug: Bugs fixed
 
@@ -41,6 +42,16 @@
 - Fix path drawing preview passing shape instead of content to next-node
 - Fix swapped arguments in CLJS PathData `-nth` with default
 - Normalize PathData coordinates to safe integer bounds on read
+- Fix RangeError from re-entrant error handling causing stack overflow [Github #8962](https://github.com/penpot/penpot/pull/8962)
+- Fix builder bool styles and media validation [Github #8963](https://github.com/penpot/penpot/pull/8963)
+- Fix "Move to" menu allowing same project as target when multiple files are selected
+- Fix crash when index query param is duplicated in URL
+- Fix wrong extremity point in path `calculate-extremities` for line-to segments
+- Fix reversed args in DTCG shadow composite token conversion
+- Fix `inside-layout?` passing shape id instead of shape to `frame-shape?`
+- Fix wrong `mapcat` call in `collect-main-shapes`
+- Fix stale accumulator in `get-children-in-instance` recursion
+- Fix typo `:podition` in swap-shapes grid cell
 
 
 ## 2.14.2
diff --git a/backend/src/app/rpc/commands/auth.clj b/backend/src/app/rpc/commands/auth.clj
index f3466f6d21..c3592d790c 100644
--- a/backend/src/app/rpc/commands/auth.clj
+++ b/backend/src/app/rpc/commands/auth.clj
@@ -446,6 +446,7 @@
           (when (:create-welcome-file params)
             (let [cfg (dissoc cfg ::db/conn)]
               (wrk/submit! executor (create-welcome-file cfg profile)))))]
+
     (cond
       ;; When profile is blocked, we just ignore it and return plain data
       (:is-blocked profile)
@@ -453,7 +454,8 @@
         (l/wrn :hint "register attempt for already blocked profile"
                :profile-id (str  (:id profile))
                :profile-email (:email profile))
-        (rph/with-meta {:email (:email profile)}
+        (rph/with-meta {:id (:id profile)
+                        :email (:email profile)}
           {::audit/replace-props props
            ::audit/context {:action "ignore-because-blocked"}
            ::audit/profile-id (:id profile)
@@ -469,7 +471,9 @@
               (:member-email invitation)))
       (let [invitation (assoc invitation :member-id  (:id profile))
             token      (tokens/generate cfg invitation)]
-        (-> {:invitation-token token}
+        (-> {:id (:id profile)
+             :email (:email profile)
+             :invitation-token token}
             (rph/with-transform (session/create-fn cfg profile claims))
             (rph/with-meta {::audit/replace-props props
                             ::audit/context {:action "accept-invitation"}
@@ -492,7 +496,8 @@
           (when-not (eml/has-reports? conn (:email profile))
             (send-email-verification! cfg profile))
 
-          (-> {:email (:email profile)}
+          (-> {:id (:id profile)
+               :email (:email profile)}
               (rph/with-defer create-welcome-file-when-needed)
               (rph/with-meta
                 {::audit/replace-props props
@@ -519,7 +524,8 @@
                       {:id (:id profile)})
           (send-email-verification! cfg profile))
 
-        (rph/with-meta {:email (:email profile)}
+        (rph/with-meta {:email (:email profile)
+                        :id (:id profile)}
           {::audit/replace-props (audit/profile->props profile)
            ::audit/context {:action action}
            ::audit/profile-id (:id profile)
diff --git a/common/src/app/common/colors.cljc b/common/src/app/common/colors.cljc
index e16acf94a3..ab7c7e2a76 100644
--- a/common/src/app/common/colors.cljc
+++ b/common/src/app/common/colors.cljc
@@ -487,62 +487,3 @@
         b (+ (* bh 100) (* bv 10))]
     (compare a b)))
 
-(defn interpolate-color
-  [c1 c2 offset]
-  (cond
-    (<= offset (:offset c1)) (assoc c1 :offset offset)
-    (>= offset (:offset c2)) (assoc c2 :offset offset)
-
-    :else
-    (let [tr-offset (/ (- offset (:offset c1)) (- (:offset c2) (:offset c1)))
-          [r1 g1 b1] (hex->rgb (:color c1))
-          [r2 g2 b2] (hex->rgb (:color c2))
-          a1 (:opacity c1)
-          a2 (:opacity c2)
-          r (+ r1 (* (- r2 r1) tr-offset))
-          g (+ g1 (* (- g2 g1) tr-offset))
-          b (+ b1 (* (- b2 b1) tr-offset))
-          a (+ a1 (* (- a2 a1) tr-offset))]
-      {:color (rgb->hex [r g b])
-       :opacity a
-       :r r
-       :g g
-       :b b
-       :alpha a
-       :offset offset})))
-
-(defn- offset-spread
-  [from to num]
-  (->> (range 0 num)
-       (map #(mth/precision (+ from (* (/ (- to from) (dec num)) %)) 2))))
-
-(defn uniform-spread?
-  "Checks if the gradient stops are spread uniformly"
-  [stops]
-  (let [cs          (count stops)
-        from        (first stops)
-        to          (last stops)
-        expect-vals (offset-spread (:offset from) (:offset to) cs)
-
-        calculate-expected
-        (fn [expected-offset stop]
-          (and (mth/close? (:offset stop) expected-offset)
-               (let [ec (interpolate-color from to expected-offset)]
-                 (and (= (:color ec) (:color stop))
-                      (= (:opacity ec) (:opacity stop))))))]
-    (->> (map calculate-expected expect-vals stops)
-         (every? true?))))
-
-(defn uniform-spread
-  "Assign an uniform spread to the offset values for the gradient"
-  [from to num-stops]
-  (->> (offset-spread (:offset from) (:offset to) num-stops)
-       (mapv (fn [offset]
-               (interpolate-color from to offset)))))
-
-(defn interpolate-gradient
-  [stops offset]
-  (let [idx   (d/index-of-pred stops #(<= offset (:offset %)))
-        start (if (= idx 0) (first stops) (get stops (dec idx)))
-        end   (if (nil? idx) (last stops) (get stops idx))]
-    (interpolate-color start end offset)))
diff --git a/common/src/app/common/data.cljc b/common/src/app/common/data.cljc
index 414179753c..2d7ad94ef2 100644
--- a/common/src/app/common/data.cljc
+++ b/common/src/app/common/data.cljc
@@ -5,7 +5,7 @@
 ;; Copyright (c) KALEIDOS INC
 
 (ns app.common.data
-  "A collection if helpers for working with data structures and other
+  "A collection of helpers for working with data structures and other
   data resources."
   (:refer-clojure :exclude [read-string hash-map merge name update-vals
                             parse-double group-by iteration concat mapcat
@@ -143,7 +143,7 @@
     (oassoc-in o (cons k ks) v)))
 
 (defn vec2
-  "Creates a optimized vector compatible type of length 2 backed
+  "Creates an optimized vector compatible type of length 2 backed
   internally with MapEntry impl because it has faster access method
   for its fields."
   [o1 o2]
@@ -252,13 +252,13 @@
   ([items] (enumerate items 0))
   ([items start]
    (loop [idx   start
-          items items
+          items (seq items)
           res   (transient [])]
-     (if (empty? items)
-       (persistent! res)
+     (if items
        (recur (inc idx)
-              (rest items)
-              (conj! res [idx (first items)]))))))
+              (next items)
+              (conj! res [idx (first items)]))
+       (persistent! res)))))
 
 (defn group-by
   ([kf coll] (group-by kf identity [] coll))
@@ -291,15 +291,12 @@
 
 (defn index-of-pred
   [coll pred]
-  (loop [c    (first coll)
-         coll (rest coll)
+  (loop [s     (seq coll)
          index 0]
-    (if (nil? c)
-      nil
-      (if (pred c)
+    (when s
+      (if (pred (first s))
         index
-        (recur (first coll)
-               (rest coll)
+        (recur (next s)
                (inc index))))))
 
 (defn index-of
@@ -377,7 +374,7 @@
                (assoc object key nil)
 
                (nil? value)
-               (dissoc object key value)
+               (dissoc object key)
 
                :else
                (assoc object key value)))
@@ -396,7 +393,7 @@
               (subvec v (inc index))))
 
 (defn without-obj
-  "Clear collection from specified obj and without nil values."
+  "Return a vector with all elements equal to `o` removed."
   [coll o]
   (into [] (filter #(not= % o)) coll))
 
@@ -404,7 +401,7 @@
   (map vector col1 col2))
 
 (defn zip-all
-  "Return a zip of both collections, extended to the lenght of the longest one,
+  "Return a zip of both collections, extended to the length of the longest one,
    and padding the shorter one with nils as needed."
   [col1 col2]
   (let [diff (- (count col1) (count col2))]
@@ -423,9 +420,9 @@
               coll)))
 
 (defn removev
-  "Returns a vector of the items in coll for which (fn item) returns logical false"
-  [fn coll]
-  (filterv (comp not fn) coll))
+  "Returns a vector of the items in coll for which (pred item) returns logical false"
+  [pred coll]
+  (filterv (comp not pred) coll))
 
 (defn filterm
   "Filter values of a map that satisfy a predicate"
@@ -443,7 +440,7 @@
 
   Optional parameters:
   `pred?`   A predicate that if not satisfied won't process the pair
-  `target?` A collection that will be used as seed to be stored
+  `target`  A collection that will be used as seed to be stored
 
   Example:
   (map-perm vector [1 2 3 4]) => [[1 2] [1 3] [1 4] [2 3] [2 4] [3 4]]"
@@ -602,12 +599,9 @@
   (let [do-map
         (fn [entry]
           (let [[k v] (mfn entry)]
-            (cond
-              (or (vector? v) (map? v))
+            (if (or (vector? v) (map? v))
               [k (deep-mapm mfn v)]
-
-              :else
-              (mfn [k v]))))]
+              [k v])))]
     (cond
       (map? m)
       (into {} (map do-map) m)
@@ -724,7 +718,7 @@
 (defn nan?
   [v]
   #?(:cljs (js/isNaN v)
-     :clj  (not= v v)))
+     :clj  (and (number? v) (Double/isNaN v))))
 
 (defn- impl-parse-integer
   [v]
@@ -788,7 +782,8 @@
                 (not (js/isNaN v))
                 (not (js/isNaN (parse-double v))))
 
-     :clj  (not= (parse-double v :nan) :nan)))
+     :clj  (and (string? v)
+                (not= (parse-double v :nan) :nan))))
 
 (defn read-string
   [v]
@@ -958,7 +953,7 @@
               (assoc diff key (map-diff v1 v2))
 
               :else
-              (assoc diff key [(get m1 key) (get m2 key)]))))]
+              (assoc diff key [v1 v2]))))]
 
     (->> keys
          (reduce diff-attr {}))))
@@ -1123,8 +1118,7 @@
   ([value {:keys [precision] :or {precision 2}}]
    (let [value (if (string? value) (parse-double value) value)]
      (when (num? value)
-       (let [value (format-precision value precision)]
-         (str value))))))
+       (format-precision value precision)))))
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; Util protocols
@@ -1152,20 +1146,20 @@
   "Wrapper around subvec so it doesn't throw an exception but returns nil instead"
   ([v start]
    (when (and (some? v)
-              (> start 0) (< start (count v)))
+              (>= start 0) (< start (count v)))
      (subvec v start)))
   ([v start end]
-   (let [size (count v)]
-     (when (and (some? v)
-                (>= start 0) (< start size)
-                (>= end 0) (<= start end) (<= end size))
-       (subvec v start end)))))
+   (when (some? v)
+     (let [size (count v)]
+       (when (and (>= start 0) (< start size)
+                  (>= end 0) (<= start end) (<= end size))
+         (subvec v start end))))))
 
 (defn append-class
   [class current-class]
-  (str (if (some? class) (str class " ") "")
-       current-class))
-
+  (if (seq class)
+    (str class " " current-class)
+    current-class))
 
 (defn nth-index-of*
   "Finds the nth occurrence of `char` in `string`, searching either forward or backward.
@@ -1201,4 +1195,4 @@
   "Returns the index of the nth occurrence of `char` in `string`, searching right to left.
    Returns nil if fewer than n occurrences exist."
   [string char n]
-  (nth-index-of* string char n :backward))
\ No newline at end of file
+  (nth-index-of* string char n :backward))
diff --git a/common/src/app/common/files/builder.cljc b/common/src/app/common/files/builder.cljc
index 4354986b8d..cc3dd11879 100644
--- a/common/src/app/common/files/builder.cljc
+++ b/common/src/app/common/files/builder.cljc
@@ -356,7 +356,7 @@
                 :code :empty-children
                 :hint "expected a group with at least one shape for creating a bool"))
 
-    (let [head  (if (= type :difference)
+    (let [head  (if (= (:bool-type bool-shape) :difference)
                   (first children)
                   (last children))
           fills (if (and (contains? head :svg-attrs) (empty? (:fills head)))
@@ -364,7 +364,7 @@
                   (get head :fills))]
       (-> bool-shape
           (assoc :fills fills)
-          (assoc :stroks (get head :strokes))))))
+          (assoc :strokes (get head :strokes))))))
 
 (defn add-bool
   [state params]
@@ -576,7 +576,7 @@
         {:keys [id width height name]}
         (-> params
             (update :id default-uuid)
-            (check-add-file-media params))]
+            (check-add-file-media))]
 
     (-> state
         (update ::blobs assoc media-id blob)
diff --git a/common/src/app/common/files/changes.cljc b/common/src/app/common/files/changes.cljc
index 673a3a854a..5b45a7ecd4 100644
--- a/common/src/app/common/files/changes.cljc
+++ b/common/src/app/common/files/changes.cljc
@@ -439,7 +439,7 @@
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 (defn- without-obj
-  "Clear collection from specified obj and without nil values."
+  "Return a vector with all elements equal to `o` removed."
   [coll o]
   (into [] (filter #(not= % o)) coll))
 
diff --git a/common/src/app/common/types/color.cljc b/common/src/app/common/types/color.cljc
index c4532c4ac0..ae56250d96 100644
--- a/common/src/app/common/types/color.cljc
+++ b/common/src/app/common/types/color.cljc
@@ -720,8 +720,10 @@
 
 (defn- offset-spread
   [from to num]
-  (->> (range 0 num)
-       (map #(mth/precision (+ from (* (/ (- to from) (dec num)) %)) 2))))
+  (if (<= num 1)
+    [from]
+    (->> (range 0 num)
+         (map #(mth/precision (+ from (* (/ (- to from) (dec num)) %)) 2)))))
 
 (defn uniform-spread?
   "Checks if the gradient stops are spread uniformly"
@@ -750,6 +752,9 @@
 (defn interpolate-gradient
   [stops offset]
   (let [idx   (d/index-of-pred stops #(<= offset (:offset %)))
-        start (if (= idx 0) (first stops) (get stops (dec idx)))
+        start (cond
+                (nil? idx) (last stops)
+                (= idx 0)  (first stops)
+                :else      (get stops (dec idx)))
         end   (if (nil? idx) (last stops) (get stops idx))]
     (interpolate-color start end offset)))
diff --git a/common/src/app/common/types/container.cljc b/common/src/app/common/types/container.cljc
index df9ce86be2..20e7ed3614 100644
--- a/common/src/app/common/types/container.cljc
+++ b/common/src/app/common/types/container.cljc
@@ -106,8 +106,9 @@
             (let [shape (get objects id)]
               (if (and (ctk/instance-head? shape) (seq children))
                 children
-                (into (conj children shape)
-                      (mapcat #(get-children-rec children %) (:shapes shape))))))]
+                (let [children' (conj children shape)]
+                  (into children'
+                        (mapcat #(get-children-rec children' %) (:shapes shape)))))))]
     (get-children-rec [] id)))
 
 (defn get-component-shape
@@ -440,7 +441,7 @@
   (if (ctk/main-instance? shape)
     [shape]
     (if-let [children (cfh/get-children objects (:id shape))]
-      (mapcat collect-main-shapes children objects)
+      (mapcat #(collect-main-shapes % objects) children)
       [])))
 
 (defn get-component-from-shape
diff --git a/common/src/app/common/types/fills/impl.cljc b/common/src/app/common/types/fills/impl.cljc
index 06475d183f..b429c67b9c 100644
--- a/common/src/app/common/types/fills/impl.cljc
+++ b/common/src/app/common/types/fills/impl.cljc
@@ -380,7 +380,7 @@
          nil))
 
      (-nth [_ i default]
-       (if (d/in-range? i size)
+       (if (d/in-range? size i)
          (read-fill dbuffer mbuffer i)
          default))
 
diff --git a/common/src/app/common/types/objects_map.cljc b/common/src/app/common/types/objects_map.cljc
index d08330765c..3604961f11 100644
--- a/common/src/app/common/types/objects_map.cljc
+++ b/common/src/app/common/types/objects_map.cljc
@@ -278,7 +278,7 @@
                (set! (.-cache this) (c/-assoc cache k v))
                v)
              (do
-               (set! (.-cache this) (assoc cache key nil))
+               (set! (.-cache this) (assoc cache k nil))
                nil))))
 
      (-lookup [this k not-found]
diff --git a/common/src/app/common/types/path/segment.cljc b/common/src/app/common/types/path/segment.cljc
index bcbbe8eeda..45fc1ba2bb 100644
--- a/common/src/app/common/types/path/segment.cljc
+++ b/common/src/app/common/types/path/segment.cljc
@@ -812,7 +812,7 @@
             :line-to
             (recur (cond-> points
                      (and from-p to-p)
-                     (-> (conj! move-p)
+                     (-> (conj! from-p)
                          (conj! to-p)))
                    (not-empty (subvec content 1))
                    to-p
diff --git a/common/src/app/common/types/shape/layout.cljc b/common/src/app/common/types/shape/layout.cljc
index 384029a688..caea9d5f91 100644
--- a/common/src/app/common/types/shape/layout.cljc
+++ b/common/src/app/common/types/shape/layout.cljc
@@ -262,7 +262,7 @@
         (or (nil? current) (= current-id parent-id))
         false
 
-        (cfh/frame-shape? current-id)
+        (cfh/frame-shape? current)
         (:layout current)
 
         :else
@@ -1439,7 +1439,7 @@
         (update-in [:layout-grid-cells id-from]
                    assoc
                    :shapes (:shapes cell-to)
-                   :podition (:position cell-to))
+                   :position (:position cell-to))
         (update-in [:layout-grid-cells id-to]
                    assoc
                    :shapes (:shapes cell-from)
diff --git a/common/src/app/common/types/token.cljc b/common/src/app/common/types/token.cljc
index 55ecc842e7..a64a15dd45 100644
--- a/common/src/app/common/types/token.cljc
+++ b/common/src/app/common/types/token.cljc
@@ -346,7 +346,6 @@
 (def typography-keys (set/union font-family-keys
                                 font-size-keys
                                 font-weight-keys
-                                font-weight-keys
                                 letter-spacing-keys
                                 line-height-keys
                                 text-case-keys
diff --git a/common/src/app/common/types/tokens_lib.cljc b/common/src/app/common/types/tokens_lib.cljc
index 269848f8e4..050de69c02 100644
--- a/common/src/app/common/types/tokens_lib.cljc
+++ b/common/src/app/common/types/tokens_lib.cljc
@@ -1637,7 +1637,7 @@ Will return a value that matches this schema:
   [value]
   (let [process-shadow (fn [shadow]
                          (if (map? shadow)
-                           (let [legacy-shadow-type (get "type" shadow)]
+                           (let [legacy-shadow-type (get shadow "type")]
                              (-> shadow
                                  (set/rename-keys {"x" :offset-x
                                                    "offsetX" :offset-x
diff --git a/common/test/common_tests/colors_test.cljc b/common/test/common_tests/colors_test.cljc
index de505fd540..7d6b0f0e3d 100644
--- a/common/test/common_tests/colors_test.cljc
+++ b/common/test/common_tests/colors_test.cljc
@@ -9,91 +9,8 @@
    #?(:cljs [goog.color :as gcolors])
    [app.common.colors :as c]
    [app.common.math :as mth]
-   [app.common.types.color :as colors]
    [clojure.test :as t]))
 
-(t/deftest valid-hex-color
-  (t/is (false? (colors/valid-hex-color? nil)))
-  (t/is (false? (colors/valid-hex-color? "")))
-  (t/is (false? (colors/valid-hex-color? "#")))
-  (t/is (false? (colors/valid-hex-color? "#qqqqqq")))
-  (t/is (true? (colors/valid-hex-color? "#aaa")))
-  (t/is (false? (colors/valid-hex-color? "#aaaa")))
-  (t/is (true? (colors/valid-hex-color? "#fabada"))))
-
-(t/deftest valid-rgb-color
-  (t/is (false? (colors/valid-rgb-color? nil)))
-  (t/is (false? (colors/valid-rgb-color? "")))
-  (t/is (false? (colors/valid-rgb-color? "()")))
-  (t/is (true? (colors/valid-rgb-color? "(255, 30, 30)")))
-  (t/is (true? (colors/valid-rgb-color? "rgb(255, 30, 30)"))))
-
-(t/deftest rgb-to-str
-  (t/is (= "rgb(1,2,3)" (colors/rgb->str [1 2 3])))
-  (t/is (= "rgba(1,2,3,4)" (colors/rgb->str [1 2 3 4]))))
-
-(t/deftest rgb-to-hsv
-  ;; (prn (colors/rgb->hsv [1 2 3]))
-  ;; (prn (gcolors/rgbToHsv 1 2 3))
-  (t/is (= [210.0 0.6666666666666666 3.0] (colors/rgb->hsv [1.0 2.0 3.0])))
-  #?(:cljs (t/is (= (colors/rgb->hsv [1 2 3]) (vec (gcolors/rgbToHsv 1 2 3))))))
-
-(t/deftest hsv-to-rgb
-  (t/is (= [1 2 3]
-           (colors/hsv->rgb [210 0.6666666666666666 3])))
-  #?(:cljs
-     (t/is (= (colors/hsv->rgb [210 0.6666666666666666 3])
-              (vec (gcolors/hsvToRgb 210 0.6666666666666666 3))))))
-
-(t/deftest rgb-to-hex
-  (t/is (= "#010203" (colors/rgb->hex [1 2 3]))))
-
-(t/deftest hex-to-rgb
-  (t/is (= [0 0 0] (colors/hex->rgb "#kkk")))
-  (t/is (= [1 2 3] (colors/hex->rgb "#010203"))))
-
-(t/deftest format-hsla
-  (t/is (= "210, 50%, 0.78%, 1" (colors/format-hsla [210.0 0.5 0.00784313725490196 1])))
-  (t/is (= "220, 5%, 30%, 0.8" (colors/format-hsla [220.0 0.05 0.3 0.8]))))
-
-(t/deftest format-rgba
-  (t/is (= "210, 199, 12, 0.08" (colors/format-rgba [210 199 12 0.08])))
-  (t/is (= "210, 199, 12, 1" (colors/format-rgba [210 199 12 1]))))
-
-(t/deftest rgb-to-hsl
-  (t/is (= [210.0 0.5 0.00784313725490196] (colors/rgb->hsl [1 2 3])))
-  #?(:cljs (t/is (= (colors/rgb->hsl [1 2 3])
-                    (vec (gcolors/rgbToHsl 1 2 3))))))
-
-(t/deftest hsl-to-rgb
-  (t/is (= [1 2 3] (colors/hsl->rgb [210.0 0.5 0.00784313725490196])))
-  (t/is (= [210.0 0.5 0.00784313725490196] (colors/rgb->hsl [1 2 3])))
-  #?(:cljs (t/is (= (colors/hsl->rgb [210 0.5 0.00784313725490196])
-                    (vec (gcolors/hslToRgb 210 0.5 0.00784313725490196))))))
-
-(t/deftest expand-hex
-  (t/is (= "aaaaaa" (colors/expand-hex "a")))
-  (t/is (= "aaaaaa" (colors/expand-hex "aa")))
-  (t/is (= "aaaaaa" (colors/expand-hex "aaa")))
-  (t/is (= "aaaa" (colors/expand-hex "aaaa"))))
-
-(t/deftest prepend-hash
-  (t/is "#aaa" (colors/prepend-hash "aaa"))
-  (t/is "#aaa" (colors/prepend-hash "#aaa")))
-
-(t/deftest remove-hash
-  (t/is "aaa" (colors/remove-hash "aaa"))
-  (t/is "aaa" (colors/remove-hash "#aaa")))
-
-(t/deftest color-string-pred
-  (t/is (true? (colors/color-string? "#aaa")))
-  (t/is (true? (colors/color-string? "(10,10,10)")))
-  (t/is (true? (colors/color-string? "rgb(10,10,10)")))
-  (t/is (true? (colors/color-string? "magenta")))
-  (t/is (false? (colors/color-string? nil)))
-  (t/is (false? (colors/color-string? "")))
-  (t/is (false? (colors/color-string? "kkkkkk"))))
-
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; app.common.colors tests
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
@@ -387,55 +304,3 @@
   (t/is (= 0.25 (c/reduce-range 0.3 4)))
   (t/is (= 0.0  (c/reduce-range 0.0 10))))
 
-;; --- Gradient helpers
-
-(t/deftest ac-interpolate-color
-  (let [c1 {:color "#000000" :opacity 0.0 :offset 0.0}
-        c2 {:color "#ffffff" :opacity 1.0 :offset 1.0}]
-    ;; At c1's offset → c1 with updated offset
-    (let [result (c/interpolate-color c1 c2 0.0)]
-      (t/is (= "#000000" (:color result)))
-      (t/is (= 0.0 (:opacity result))))
-    ;; At c2's offset → c2 with updated offset
-    (let [result (c/interpolate-color c1 c2 1.0)]
-      (t/is (= "#ffffff" (:color result)))
-      (t/is (= 1.0 (:opacity result))))
-    ;; At midpoint → gray
-    (let [result (c/interpolate-color c1 c2 0.5)]
-      (t/is (= "#7f7f7f" (:color result)))
-      (t/is (mth/close? (:opacity result) 0.5)))))
-
-(t/deftest ac-uniform-spread
-  (let [c1 {:color "#000000" :opacity 0.0 :offset 0.0}
-        c2 {:color "#ffffff" :opacity 1.0 :offset 1.0}
-        stops (c/uniform-spread c1 c2 3)]
-    (t/is (= 3 (count stops)))
-    (t/is (= 0.0 (:offset (first stops))))
-    (t/is (mth/close? 0.5 (:offset (second stops))))
-    (t/is (= 1.0 (:offset (last stops))))))
-
-(t/deftest ac-uniform-spread?
-  (let [c1 {:color "#000000" :opacity 0.0 :offset 0.0}
-        c2 {:color "#ffffff" :opacity 1.0 :offset 1.0}
-        stops (c/uniform-spread c1 c2 3)]
-    ;; A uniformly spread result should pass the predicate
-    (t/is (true? (c/uniform-spread? stops))))
-  ;; Manual non-uniform stops should not pass
-  (let [stops [{:color "#000000" :opacity 0.0 :offset 0.0}
-               {:color "#888888" :opacity 0.5 :offset 0.3}
-               {:color "#ffffff" :opacity 1.0 :offset 1.0}]]
-    (t/is (false? (c/uniform-spread? stops)))))
-
-(t/deftest ac-interpolate-gradient
-  (let [stops [{:color "#000000" :opacity 0.0 :offset 0.0}
-               {:color "#ffffff" :opacity 1.0 :offset 1.0}]]
-    ;; At start
-    (let [result (c/interpolate-gradient stops 0.0)]
-      (t/is (= "#000000" (:color result))))
-    ;; At end
-    (let [result (c/interpolate-gradient stops 1.0)]
-      (t/is (= "#ffffff" (:color result))))
-    ;; In the middle
-    (let [result (c/interpolate-gradient stops 0.5)]
-      (t/is (= "#7f7f7f" (:color result))))))
-
diff --git a/common/test/common_tests/data_test.cljc b/common/test/common_tests/data_test.cljc
index c77c7393cd..44cd24a237 100644
--- a/common/test/common_tests/data_test.cljc
+++ b/common/test/common_tests/data_test.cljc
@@ -349,6 +349,8 @@
   (t/is (= [2 3] (d/safe-subvec [1 2 3 4] 1 3)))
   ;; single arg — from index to end
   (t/is (= [2 3 4] (d/safe-subvec [1 2 3 4] 1)))
+  ;; start=0 returns the full vector
+  (t/is (= [1 2 3 4] (d/safe-subvec [1 2 3 4] 0)))
   ;; out-of-range returns nil
   (t/is (nil? (d/safe-subvec [1 2 3] 5)))
   (t/is (nil? (d/safe-subvec [1 2 3] 0 5)))
@@ -396,12 +398,19 @@
   (t/is (= 0 (d/index-of-pred [1 2 3] odd?)))
   (t/is (= 1 (d/index-of-pred [2 3 4] odd?)))
   (t/is (nil? (d/index-of-pred [2 4 6] odd?)))
-  (t/is (nil? (d/index-of-pred [] odd?))))
+  (t/is (nil? (d/index-of-pred [] odd?)))
+  ;; works correctly when collection contains nil elements
+  (t/is (= 2 (d/index-of-pred [nil nil 3] some?)))
+  (t/is (= 0 (d/index-of-pred [nil 1 2] nil?)))
+  ;; works correctly when collection contains false elements
+  (t/is (= 1 (d/index-of-pred [false true false] true?))))
 
 (t/deftest index-of-test
   (t/is (= 0 (d/index-of [:a :b :c] :a)))
   (t/is (= 2 (d/index-of [:a :b :c] :c)))
-  (t/is (nil? (d/index-of [:a :b :c] :z))))
+  (t/is (nil? (d/index-of [:a :b :c] :z)))
+  ;; works when searching for nil in a collection
+  (t/is (= 1 (d/index-of [:a nil :c] nil))))
 
 (t/deftest replace-by-id-test
   (let [items [{:id 1 :v "a"} {:id 2 :v "b"} {:id 3 :v "c"}]
@@ -469,6 +478,8 @@
   (t/is (= {:a {:x 10 :y 2}} (d/patch-object {:a {:x 1 :y 2}} {:a {:x 10}})))
   ;; nested nil removes nested key
   (t/is (= {:a {:y 2}} (d/patch-object {:a {:x 1 :y 2}} {:a {:x nil}})))
+  ;; nil value removes only the specified key, not other keys
+  (t/is (= {nil 0 :b 2} (d/patch-object {nil 0 :a 1 :b 2} {:a nil})))
   ;; transducer arity (1-arg returns a fn)
   (let [f (d/patch-object {:a 99})]
     (t/is (= {:a 99 :b 2} (f {:a 1 :b 2})))))
@@ -560,33 +571,33 @@
            (into [] (d/distinct-xf :id) [{:id 1 :v "a"} {:id 2 :v "x"} {:id 2 :v "b"}]))))
 
 (t/deftest deep-mapm-test
-  ;; Note: mfn is called twice on leaf entries (once initially, once again
-  ;; after checking if the value is a map/vector), so a doubling fn applied
-  ;; to value 1 gives 1*2*2=4.
-  (t/is (= {:a 4 :b {:c 8}}
+  ;; mfn is applied once per entry
+  (t/is (= {:a 2 :b {:c 4}}
            (d/deep-mapm (fn [[k v]] [k (if (number? v) (* v 2) v)])
                         {:a 1 :b {:c 2}})))
-  ;; Keyword renaming: keys are also transformed — and applied twice.
-  ;; Use an idempotent key transformation (uppercase once = uppercase twice).
+  ;; Keyword renaming: keys are transformed once per entry
   (let [result (d/deep-mapm (fn [[k v]] [(keyword (str (name k) "!")) v])
                             {:a 1})]
-    (t/is (contains? result (keyword "a!!")))))
+    (t/is (contains? result (keyword "a!"))))
+  ;; Vectors inside maps are recursed into
+  (t/is (= {:items [{:x 10}]}
+           (d/deep-mapm (fn [[k v]] [k (if (number? v) (* v 10) v)])
+                        {:items [{:x 1}]})))
+  ;; Plain scalar at top level map
+  (t/is (= {:a "hello"} (d/deep-mapm identity {:a "hello"}))))
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; Numeric helpers
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 (t/deftest nan-test
-  ;; Note: nan? behaves differently per platform:
-  ;; - CLJS: uses js/isNaN, returns true for ##NaN
-  ;; - CLJ: uses (not= v v); Clojure's = uses .equals on doubles,
-  ;;   so (= ##NaN ##NaN) is true and nan? returns false for ##NaN.
-  ;; Either way, nan? returns false for regular numbers and nil.
+  (t/is (d/nan? ##NaN))
   (t/is (not (d/nan? 0)))
   (t/is (not (d/nan? 1)))
   (t/is (not (d/nan? nil)))
-  ;; Platform-specific: JS nan? correctly detects NaN
-  #?(:cljs (t/is (d/nan? ##NaN))))
+  ;; CLJS js/isNaN coerces non-numbers; JVM Double/isNaN is number-only
+  #?(:cljs (t/is (d/nan? "hello")))
+  #?(:clj  (t/is (not (d/nan? "hello")))))
 
 (t/deftest safe-plus-test
   (t/is (= 5 (d/safe+ 3 2)))
@@ -630,18 +641,13 @@
   (t/is (nil? (d/parse-uuid nil))))
 
 (t/deftest coalesce-str-test
-  ;; On JVM: nan? uses (not= v v), which is false for all normal values.
-  ;; On CLJS: nan? uses js/isNaN, which is true for non-numeric strings.
-  ;; coalesce-str returns default when value is nil or nan?.
   (t/is (= "default" (d/coalesce-str nil "default")))
   ;; Numbers always stringify on both platforms
   (t/is (= "42" (d/coalesce-str 42 "default")))
-  ;; ##NaN: nan? is true in CLJS, returns default;
-  ;;        nan? is false in CLJ, so str(##NaN)="NaN" is returned.
-  #?(:cljs (t/is (= "default" (d/coalesce-str ##NaN "default"))))
-  #?(:clj  (t/is (= "NaN" (d/coalesce-str ##NaN "default"))))
+  ;; ##NaN returns default on both platforms now that nan? is fixed on JVM
+  (t/is (= "default" (d/coalesce-str ##NaN "default")))
   ;; Strings: in CLJS js/isNaN("hello")=true so "default" is returned;
-  ;;          in CLJ nan? is false so (str "hello")="hello" is returned.
+  ;;          in CLJ nan? is false for strings so (str "hello")="hello" is returned.
   #?(:cljs (t/is (= "default" (d/coalesce-str "hello" "default"))))
   #?(:clj  (t/is (= "hello" (d/coalesce-str "hello" "default")))))
 
@@ -803,7 +809,8 @@
 (t/deftest append-class-test
   (t/is (= "foo bar" (d/append-class "foo" "bar")))
   (t/is (= "bar" (d/append-class nil "bar")))
-  (t/is (= " bar" (d/append-class "" "bar"))))
+  ;; empty string is treated like nil — no leading space
+  (t/is (= "bar" (d/append-class "" "bar"))))
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; Additional helpers (5th batch)
@@ -852,6 +859,9 @@
   (t/is (d/num-string? "-7"))
   (t/is (not (d/num-string? "hello")))
   (t/is (not (d/num-string? nil)))
+  ;; non-string types always return false
+  (t/is (not (d/num-string? 42)))
+  (t/is (not (d/num-string? :keyword)))
   ;; In CLJS, js/isNaN("") → false (empty string coerces to 0), so "" is numeric
   #?(:clj (t/is (not (d/num-string? ""))))
   #?(:cljs (t/is (d/num-string? ""))))
diff --git a/common/test/common_tests/files_builder_test.cljc b/common/test/common_tests/files_builder_test.cljc
new file mode 100644
index 0000000000..23dd6c78cc
--- /dev/null
+++ b/common/test/common_tests/files_builder_test.cljc
@@ -0,0 +1,72 @@
+;; This Source Code Form is subject to the terms of the Mozilla Public
+;; License, v. 2.0. If a copy of the MPL was not distributed with this
+;; file, You can obtain one at http://mozilla.org/MPL/2.0/.
+;;
+;; Copyright (c) KALEIDOS INC
+
+(ns common-tests.files-builder-test
+  (:require
+   [app.common.files.builder :as fb]
+   [app.common.uuid :as uuid]
+   [clojure.test :as t]))
+
+(defn- stroke
+  [color]
+  [{:stroke-style :solid
+    :stroke-alignment :inner
+    :stroke-width 1
+    :stroke-color color
+    :stroke-opacity 1}])
+
+(t/deftest add-bool-uses-difference-head-style
+  (let [file-id  (uuid/next)
+        page-id  (uuid/next)
+        group-id (uuid/next)
+        child-a  (uuid/next)
+        child-b  (uuid/next)
+        state    (-> (fb/create-state)
+                     (fb/add-file {:id file-id :name "Test file"})
+                     (fb/add-page {:id page-id :name "Page 1"})
+                     (fb/add-group {:id group-id :name "Group A"})
+                     (fb/add-shape {:id child-a
+                                    :type :rect
+                                    :name "A"
+                                    :x 0
+                                    :y 0
+                                    :width 10
+                                    :height 10
+                                    :strokes (stroke "#ff0000")})
+                     (fb/add-shape {:id child-b
+                                    :type :rect
+                                    :name "B"
+                                    :x 20
+                                    :y 0
+                                    :width 10
+                                    :height 10
+                                    :strokes (stroke "#00ff00")})
+                     (fb/close-group)
+                     (fb/add-bool {:group-id group-id
+                                   :type :difference}))
+        bool     (fb/get-shape state group-id)]
+    (t/is (= :bool (:type bool)))
+    (t/is (= (stroke "#ff0000") (:strokes bool)))))
+
+(t/deftest add-file-media-validates-and-persists-media
+  (let [file-id  (uuid/next)
+        page-id  (uuid/next)
+        image-id (uuid/next)
+        state    (-> (fb/create-state)
+                     (fb/add-file {:id file-id :name "Test file"})
+                     (fb/add-page {:id page-id :name "Page 1"})
+                     (fb/add-file-media {:id image-id
+                                         :name "Image"
+                                         :width 128
+                                         :height 64}
+                                        (fb/map->BlobWrapper {:mtype "image/png"
+                                                              :size 42
+                                                              :blob nil})))
+        media    (get-in state [::fb/file-media image-id])]
+    (t/is (= image-id (::fb/last-id state)))
+    (t/is (= "Image" (:name media)))
+    (t/is (= 128 (:width media)))
+    (t/is (= 64 (:height media)))))
diff --git a/common/test/common_tests/runner.cljc b/common/test/common_tests/runner.cljc
index 368bc4ce31..1ba7242d58 100644
--- a/common/test/common_tests/runner.cljc
+++ b/common/test/common_tests/runner.cljc
@@ -11,6 +11,7 @@
    [common-tests.buffer-test]
    [common-tests.colors-test]
    [common-tests.data-test]
+   [common-tests.files-builder-test]
    [common-tests.files-changes-test]
    [common-tests.files-migrations-test]
    [common-tests.geom-align-test]
@@ -58,6 +59,7 @@
    [common-tests.text-test]
    [common-tests.time-test]
    [common-tests.types.absorb-assets-test]
+   [common-tests.types.color-test]
    [common-tests.types.components-test]
    [common-tests.types.container-test]
    [common-tests.types.fill-test]
@@ -88,6 +90,7 @@
    'common-tests.data-test
    #?(:clj 'common-tests.fressian-test)
    'common-tests.files-changes-test
+   'common-tests.files-builder-test
    'common-tests.files-migrations-test
    'common-tests.geom-align-test
    'common-tests.geom-bounds-map-test
@@ -134,6 +137,7 @@
    'common-tests.text-test
    'common-tests.time-test
    'common-tests.types.absorb-assets-test
+   'common-tests.types.color-test
    'common-tests.types.components-test
    'common-tests.types.container-test
    'common-tests.types.fill-test
diff --git a/common/test/common_tests/types/color_test.cljc b/common/test/common_tests/types/color_test.cljc
new file mode 100644
index 0000000000..9a3ab00ac9
--- /dev/null
+++ b/common/test/common_tests/types/color_test.cljc
@@ -0,0 +1,166 @@
+;; This Source Code Form is subject to the terms of the Mozilla Public
+;; License, v. 2.0. If a copy of the MPL was not distributed with this
+;; file, You can obtain one at http://mozilla.org/MPL/2.0/.
+;;
+;; Copyright (c) KALEIDOS INC
+
+(ns common-tests.types.color-test
+  (:require
+   [app.common.math :as mth]
+   [app.common.types.color :as colors]
+   [clojure.test :as t]))
+
+;; --- Predicates
+
+(t/deftest valid-hex-color
+  (t/is (false? (colors/valid-hex-color? nil)))
+  (t/is (false? (colors/valid-hex-color? "")))
+  (t/is (false? (colors/valid-hex-color? "#")))
+  (t/is (false? (colors/valid-hex-color? "#qqqqqq")))
+  (t/is (true? (colors/valid-hex-color? "#aaa")))
+  (t/is (false? (colors/valid-hex-color? "#aaaa")))
+  (t/is (true? (colors/valid-hex-color? "#fabada"))))
+
+(t/deftest valid-rgb-color
+  (t/is (false? (colors/valid-rgb-color? nil)))
+  (t/is (false? (colors/valid-rgb-color? "")))
+  (t/is (false? (colors/valid-rgb-color? "()")))
+  (t/is (true? (colors/valid-rgb-color? "(255, 30, 30)")))
+  (t/is (true? (colors/valid-rgb-color? "rgb(255, 30, 30)"))))
+
+;; --- Conversions
+
+(t/deftest rgb-to-str
+  (t/is (= "rgb(1,2,3)" (colors/rgb->str [1 2 3])))
+  (t/is (= "rgba(1,2,3,4)" (colors/rgb->str [1 2 3 4]))))
+
+(t/deftest rgb-to-hsv
+  (t/is (= [210.0 0.6666666666666666 3.0] (colors/rgb->hsv [1.0 2.0 3.0]))))
+
+(t/deftest hsv-to-rgb
+  (t/is (= [1 2 3]
+           (colors/hsv->rgb [210 0.6666666666666666 3]))))
+
+(t/deftest rgb-to-hex
+  (t/is (= "#010203" (colors/rgb->hex [1 2 3]))))
+
+(t/deftest hex-to-rgb
+  (t/is (= [0 0 0] (colors/hex->rgb "#kkk")))
+  (t/is (= [1 2 3] (colors/hex->rgb "#010203"))))
+
+(t/deftest format-hsla
+  (t/is (= "210, 50%, 0.78%, 1" (colors/format-hsla [210.0 0.5 0.00784313725490196 1])))
+  (t/is (= "220, 5%, 30%, 0.8" (colors/format-hsla [220.0 0.05 0.3 0.8]))))
+
+(t/deftest format-rgba
+  (t/is (= "210, 199, 12, 0.08" (colors/format-rgba [210 199 12 0.08])))
+  (t/is (= "210, 199, 12, 1" (colors/format-rgba [210 199 12 1]))))
+
+(t/deftest rgb-to-hsl
+  (t/is (= [210.0 0.5 0.00784313725490196] (colors/rgb->hsl [1 2 3]))))
+
+(t/deftest hsl-to-rgb
+  (t/is (= [1 2 3] (colors/hsl->rgb [210.0 0.5 0.00784313725490196])))
+  (t/is (= [210.0 0.5 0.00784313725490196] (colors/rgb->hsl [1 2 3]))))
+
+(t/deftest expand-hex
+  (t/is (= "aaaaaa" (colors/expand-hex "a")))
+  (t/is (= "aaaaaa" (colors/expand-hex "aa")))
+  (t/is (= "aaaaaa" (colors/expand-hex "aaa")))
+  (t/is (= "aaaa" (colors/expand-hex "aaaa"))))
+
+(t/deftest prepend-hash
+  (t/is "#aaa" (colors/prepend-hash "aaa"))
+  (t/is "#aaa" (colors/prepend-hash "#aaa")))
+
+(t/deftest remove-hash
+  (t/is "aaa" (colors/remove-hash "aaa"))
+  (t/is "aaa" (colors/remove-hash "#aaa")))
+
+(t/deftest color-string-pred
+  (t/is (true? (colors/color-string? "#aaa")))
+  (t/is (true? (colors/color-string? "(10,10,10)")))
+  (t/is (true? (colors/color-string? "rgb(10,10,10)")))
+  (t/is (true? (colors/color-string? "magenta")))
+  (t/is (false? (colors/color-string? nil)))
+  (t/is (false? (colors/color-string? "")))
+  (t/is (false? (colors/color-string? "kkkkkk"))))
+
+;; --- Gradient helpers
+
+(t/deftest interpolate-color
+  (t/testing "at c1 offset returns c1 color"
+    (let [c1     {:color "#000000" :opacity 0.0 :offset 0.0}
+          c2     {:color "#ffffff" :opacity 1.0 :offset 1.0}
+          result (colors/interpolate-color c1 c2 0.0)]
+      (t/is (= "#000000" (:color result)))
+      (t/is (= 0.0 (:opacity result)))))
+  (t/testing "at c2 offset returns c2 color"
+    (let [c1     {:color "#000000" :opacity 0.0 :offset 0.0}
+          c2     {:color "#ffffff" :opacity 1.0 :offset 1.0}
+          result (colors/interpolate-color c1 c2 1.0)]
+      (t/is (= "#ffffff" (:color result)))
+      (t/is (= 1.0 (:opacity result)))))
+  (t/testing "at midpoint returns interpolated gray"
+    (let [c1     {:color "#000000" :opacity 0.0 :offset 0.0}
+          c2     {:color "#ffffff" :opacity 1.0 :offset 1.0}
+          result (colors/interpolate-color c1 c2 0.5)]
+      (t/is (= "#7f7f7f" (:color result)))
+      (t/is (mth/close? (:opacity result) 0.5)))))
+
+(t/deftest uniform-spread
+  (t/testing "produces correct count and offsets"
+    (let [c1    {:color "#000000" :opacity 0.0 :offset 0.0}
+          c2    {:color "#ffffff" :opacity 1.0 :offset 1.0}
+          stops (colors/uniform-spread c1 c2 3)]
+      (t/is (= 3 (count stops)))
+      (t/is (= 0.0 (:offset (first stops))))
+      (t/is (mth/close? 0.5 (:offset (second stops))))
+      (t/is (= 1.0 (:offset (last stops))))))
+  (t/testing "single stop returns a vector of one element (no division by zero)"
+    (let [c1    {:color "#ff0000" :opacity 1.0 :offset 0.0}
+          stops (colors/uniform-spread c1 c1 1)]
+      (t/is (= 1 (count stops))))))
+
+(t/deftest uniform-spread?
+  (t/testing "uniformly spread stops are detected as uniform"
+    (let [c1    {:color "#000000" :opacity 0.0 :offset 0.0}
+          c2    {:color "#ffffff" :opacity 1.0 :offset 1.0}
+          stops (colors/uniform-spread c1 c2 3)]
+      (t/is (true? (colors/uniform-spread? stops)))))
+  (t/testing "two-stop gradient is uniform by definition"
+    (let [stops [{:color "#ff0000" :opacity 1.0 :offset 0.0}
+                 {:color "#0000ff" :opacity 1.0 :offset 1.0}]]
+      (t/is (true? (colors/uniform-spread? stops)))))
+  (t/testing "stops with wrong offset are not uniform"
+    (let [stops [{:color "#000000" :opacity 0.0 :offset 0.0}
+                 {:color "#888888" :opacity 0.5 :offset 0.3}
+                 {:color "#ffffff" :opacity 1.0 :offset 1.0}]]
+      (t/is (false? (colors/uniform-spread? stops)))))
+  (t/testing "stops with correct offset but wrong color are not uniform"
+    (let [stops [{:color "#000000" :opacity 0.0 :offset 0.0}
+                 {:color "#aaaaaa" :opacity 0.5 :offset 0.5}
+                 {:color "#ffffff" :opacity 1.0 :offset 1.0}]]
+      (t/is (false? (colors/uniform-spread? stops))))))
+
+(t/deftest interpolate-gradient
+  (t/testing "at start offset returns first stop color"
+    (let [stops  [{:color "#000000" :opacity 0.0 :offset 0.0}
+                  {:color "#ffffff" :opacity 1.0 :offset 1.0}]
+          result (colors/interpolate-gradient stops 0.0)]
+      (t/is (= "#000000" (:color result)))))
+  (t/testing "at end offset returns last stop color"
+    (let [stops  [{:color "#000000" :opacity 0.0 :offset 0.0}
+                  {:color "#ffffff" :opacity 1.0 :offset 1.0}]
+          result (colors/interpolate-gradient stops 1.0)]
+      (t/is (= "#ffffff" (:color result)))))
+  (t/testing "at midpoint returns interpolated gray"
+    (let [stops  [{:color "#000000" :opacity 0.0 :offset 0.0}
+                  {:color "#ffffff" :opacity 1.0 :offset 1.0}]
+          result (colors/interpolate-gradient stops 0.5)]
+      (t/is (= "#7f7f7f" (:color result)))))
+  (t/testing "offset beyond last stop returns last stop color (nil idx guard)"
+    (let [stops  [{:color "#000000" :opacity 0.0 :offset 0.0}
+                  {:color "#ffffff" :opacity 1.0 :offset 0.5}]
+          result (colors/interpolate-gradient stops 1.0)]
+      (t/is (= "#ffffff" (:color result))))))
diff --git a/common/test/common_tests/types/fill_test.cljc b/common/test/common_tests/types/fill_test.cljc
index 308778bcc1..f9968e8aed 100644
--- a/common/test/common_tests/types/fill_test.cljc
+++ b/common/test/common_tests/types/fill_test.cljc
@@ -207,3 +207,18 @@
         fill1  (nth fills1 1)]
     (t/is (nil? fill1))
     (t/is (equivalent-fill? fill0 sample-fill-6))))
+
+(t/deftest indexed-access-with-default
+  (t/testing "nth with default returns fill for valid index"
+    ;; Regression: CLJS -nth with default had reversed d/in-range? args,
+    ;; so it always fell through to the default even for valid indices.
+    (let [fills    (types.fills/from-plain [sample-fill-6])
+          sentinel ::not-found
+          result   (nth fills 0 sentinel)]
+      (t/is (not= sentinel result))
+      (t/is (equivalent-fill? result sample-fill-6))))
+  (t/testing "nth with default returns default for out-of-range index"
+    (let [fills    (types.fills/from-plain [sample-fill-6])
+          sentinel ::not-found]
+      (t/is (= sentinel (nth fills 1 sentinel)))
+      (t/is (= sentinel (nth fills -1 sentinel))))))
diff --git a/common/test/common_tests/types/path_data_test.cljc b/common/test/common_tests/types/path_data_test.cljc
index e4d2881b18..6dc7fa5207 100644
--- a/common/test/common_tests/types/path_data_test.cljc
+++ b/common/test/common_tests/types/path_data_test.cljc
@@ -973,6 +973,31 @@
     (t/is (mth/close? 10.0 (:x2 rect) 0.1))
     (t/is (mth/close? 10.0 (:y2 rect) 0.1))))
 
+(t/deftest segment-content->selrect-multi-line
+  ;; Regression: calculate-extremities used move-p instead of from-p in
+  ;; the :line-to branch. For a subpath with multiple consecutive line-to
+  ;; commands, the selrect must still match the reference implementation.
+  (let [;; A subpath that starts away from the origin and has three
+        ;; line-to segments so that move-p diverges from from-p for the
+        ;; later segments.
+        segments [{:command :move-to :params {:x 5.0  :y 5.0}}
+                  {:command :line-to :params {:x 15.0 :y 0.0}}
+                  {:command :line-to :params {:x 20.0 :y 8.0}}
+                  {:command :line-to :params {:x 10.0 :y 12.0}}]
+        content  (path/content segments)
+        rect     (path.segment/content->selrect content)
+        ref-pts  (calculate-extremities segments)]
+
+    ;; Bounding box must enclose all four vertices exactly.
+    (t/is (some? rect))
+    (t/is (mth/close?  5.0 (:x1 rect) 0.1))
+    (t/is (mth/close?  0.0 (:y1 rect) 0.1))
+    (t/is (mth/close? 20.0 (:x2 rect) 0.1))
+    (t/is (mth/close? 12.0 (:y2 rect) 0.1))
+
+    ;; Must agree with the reference implementation.
+    (t/is (= ref-pts (calculate-extremities content)))))
+
 (t/deftest segment-content-center
   (let [content (path/content sample-content-square)
         center  (path.segment/content-center content)]
diff --git a/common/test/common_tests/types/shape_layout_test.cljc b/common/test/common_tests/types/shape_layout_test.cljc
index d677ed5d09..62935b21dc 100644
--- a/common/test/common_tests/types/shape_layout_test.cljc
+++ b/common/test/common_tests/types/shape_layout_test.cljc
@@ -186,13 +186,9 @@
         flex (make-flex-frame :parent-id root-id)
         child (make-shape :parent-id (:id flex))]
 
-    ;; Note: inside-layout? calls (cfh/frame-shape? current-id) with a UUID id,
-    ;; but frame-shape? checks (:type uuid) which is nil for a UUID value.
-    ;; The function therefore always returns false regardless of structure.
-    ;; These tests document the actual (not the intended) behavior.
-    (t/testing "returns false when child is under a flex frame"
+    (t/testing "returns true when child is under a flex frame"
       (let [objects {root-id root (:id flex) flex (:id child) child}]
-        (t/is (not (layout/inside-layout? objects child)))))
+        (t/is (layout/inside-layout? objects child))))
 
     (t/testing "returns false for root shape"
       (let [objects {root-id root (:id flex) flex (:id child) child}]
diff --git a/common/test/common_tests/types/tokens_lib_test.cljc b/common/test/common_tests/types/tokens_lib_test.cljc
index dfef086b1b..de18be42de 100644
--- a/common/test/common_tests/types/tokens_lib_test.cljc
+++ b/common/test/common_tests/types/tokens_lib_test.cljc
@@ -1930,7 +1930,7 @@
          (let [token (ctob/get-token-by-name lib "shadow-test" "test.shadow-with-type")]
            (t/is (some? token))
            (t/is (= :shadow (:type token)))
-           (t/is (= [{:offset-x "0", :offset-y "4px", :blur "8px", :spread "0", :color "rgba(0,0,0,0.2)", :inset false}]
+           (t/is (= [{:offset-x "0", :offset-y "4px", :blur "8px", :spread "0", :color "rgba(0,0,0,0.2)", :inset true}]
                     (:value token)))))
 
        (t/testing "shadow token with description"
diff --git a/frontend/src/app/config.cljs b/frontend/src/app/config.cljs
index a76bdf87dc..5059820ede 100644
--- a/frontend/src/app/config.cljs
+++ b/frontend/src/app/config.cljs
@@ -203,6 +203,11 @@
   (let [f (obj/get global "externalContextInfo")]
     (when (fn? f) (f))))
 
+(defn external-notify-register-success
+  [profile-id]
+  (let [f (obj/get global "externalNotifyRegisterSuccess")]
+    (when (fn? f) (f (str profile-id)))))
+
 (defn initialize-external-context-info
   []
   (let [f (obj/get global "initializeExternalConfigInfo")]
diff --git a/frontend/src/app/main/data/viewer.cljs b/frontend/src/app/main/data/viewer.cljs
index c2d42d680c..c1f6083d13 100644
--- a/frontend/src/app/main/data/viewer.cljs
+++ b/frontend/src/app/main/data/viewer.cljs
@@ -204,7 +204,7 @@
       (watch [_ state _]
         (let [route    (:route state)
               qparams  (:query-params route)
-              index    (some-> (:index qparams) parse-long)
+              index    (some-> (rt/get-query-param qparams :index) parse-long)
               frame-id (some-> (:frame-id qparams) uuid/parse)]
           (rx/merge
            (rx/of (case (:zoom qparams)
@@ -301,7 +301,7 @@
     (update [_ state]
       (let [params (rt/get-params state)
             page-id (some-> (:page-id params) uuid/parse)
-            index   (some-> (:index params) parse-long)
+            index   (some-> (rt/get-query-param params :index) parse-long)
 
             frames  (dm/get-in state [:viewer :pages page-id :frames])
             index   (min (or index 0) (max 0 (dec (count frames))))
@@ -325,7 +325,7 @@
 
       (let [params (rt/get-params state)
             page-id (some-> (:page-id params) uuid/parse)
-            index   (some-> (:index params) parse-long)
+            index   (some-> (rt/get-query-param params :index) parse-long)
 
             frames  (dm/get-in state [:viewer :pages page-id :frames])
             index   (min (or index 0) (max 0 (dec (count frames))))
@@ -399,7 +399,7 @@
     ptk/WatchEvent
     (watch [_ state _]
       (let [params  (rt/get-params state)
-            index   (some-> params :index parse-long)]
+            index   (some-> (rt/get-query-param params :index) parse-long)]
         (when (pos? index)
           (rx/of
            (dcmt/close-thread)
@@ -415,7 +415,7 @@
     ptk/WatchEvent
     (watch [_ state _]
       (let [params  (rt/get-params state)
-            index   (some-> params :index parse-long)
+            index   (some-> (rt/get-query-param params :index) parse-long)
             page-id (some-> params :page-id uuid/parse)
 
             total   (count (get-in state [:viewer :pages page-id :frames]))]
@@ -530,7 +530,7 @@
        (let [route   (:route state)
              qparams (:query-params route)
              page-id (some-> (:page-id qparams) uuid/parse)
-             index   (some-> (:index qparams) parse-long)
+             index   (some-> (rt/get-query-param qparams :index) parse-long)
              frames  (get-in state [:viewer :pages page-id :frames])
              frame   (get frames index)]
          (cond-> state
@@ -744,7 +744,7 @@
       (let [route     (:route state)
             qparams   (:query-params route)
             page-id   (some-> (:page-id qparams) uuid/parse)
-            index     (some-> (:index qparams) parse-long)
+            index     (some-> (rt/get-query-param qparams :index) parse-long)
             objects   (get-in state [:viewer :pages page-id :objects])
             frame-id  (get-in state [:viewer :pages page-id :frames index :id])
 
diff --git a/frontend/src/app/main/errors.cljs b/frontend/src/app/main/errors.cljs
index 048ac62e0a..391101d4be 100644
--- a/frontend/src/app/main/errors.cljs
+++ b/frontend/src/app/main/errors.cljs
@@ -43,6 +43,12 @@
   [_]
   false)
 
+;; Re-entrancy guard: prevents on-error from calling itself recursively.
+;; If an error occurs while we are already handling an error (e.g. the
+;; notification emit itself throws), we log it and bail out immediately
+;; instead of recursing until the call-stack overflows.
+(def ^:private handling-error? (volatile! false))
+
 ;; --- Stale-asset error detection and auto-reload
 ;;
 ;; When the browser loads JS modules from different builds (e.g.  shared.js from
@@ -90,12 +96,24 @@
         (assoc ::trace (.-stack cause)))))
 
 (defn on-error
-  "A general purpose error handler."
+  "A general purpose error handler.
+
+  Protected by a re-entrancy guard: if an error is raised while this
+  function is already on the call stack (e.g. the notification emit
+  itself fails), we print it to the console and return immediately
+  instead of recursing until the call-stack is exhausted."
   [error]
-  (if (map? error)
-    (ptk/handle-error error)
-    (let [data (exception->error-data error)]
-      (ptk/handle-error data))))
+  (if @handling-error?
+    (.error js/console "[on-error] re-entrant call suppressed" error)
+    (do
+      (vreset! handling-error? true)
+      (try
+        (if (map? error)
+          (ptk/handle-error error)
+          (let [data (exception->error-data error)]
+            (ptk/handle-error data)))
+        (finally
+          (vreset! handling-error? false))))))
 
 ;; Inject dependency to remove circular dependency
 (set! app.main.worker/on-error on-error)
@@ -148,7 +166,14 @@
                 :report report}))))
 
 (defn flash
-  "Show error notification banner and emit error report"
+  "Show error notification banner and emit error report.
+
+  The notification is scheduled asynchronously (via tm/schedule) to
+  avoid pushing a new event into the potok store while the store's own
+  error-handling pipeline is still on the call stack.  Emitting
+  synchronously from inside an error handler creates a re-entrant
+  event-processing cycle that can exhaust the JS call stack
+  (RangeError: Maximum call stack size exceeded)."
   [& {:keys [type hint cause] :or {type :handled}}]
   (when (ex/exception? cause)
     (when-let [event-name (case type
@@ -160,11 +185,12 @@
                        :report report
                        :hint (ex/get-hint cause)))))
 
-  (st/emit!
-   (ntf/show {:content (or ^boolean hint (tr "errors.generic"))
-              :type :toast
-              :level :error
-              :timeout 5000})))
+  (ts/schedule
+   #(st/emit!
+     (ntf/show {:content (or ^boolean hint (tr "errors.generic"))
+                :type :toast
+                :level :error
+                :timeout 5000}))))
 
 (defmethod ptk/handle-error :network
   [error]
diff --git a/frontend/src/app/main/router.cljs b/frontend/src/app/main/router.cljs
index 1e234e8af1..405c8b6664 100644
--- a/frontend/src/app/main/router.cljs
+++ b/frontend/src/app/main/router.cljs
@@ -136,6 +136,16 @@
   [state]
   (dm/get-in state [:route :params :query]))
 
+(defn get-query-param
+  "Safely extracts a scalar value for a query param key from a params
+  map. When the same key appears multiple times in a URL,
+  query-string->map returns a vector for that key; this function
+  always returns a single (last) element in that case, so downstream
+  consumers such as parse-long always receive a plain string or nil."
+  [params k]
+  (let [v (get params k)]
+    (if (sequential? v) (peek v) v)))
+
 (defn nav-back
   []
   (ptk/reify ::nav-back
diff --git a/frontend/src/app/main/ui.cljs b/frontend/src/app/main/ui.cljs
index 7a2b6ef86a..67795c2ff3 100644
--- a/frontend/src/app/main/ui.cljs
+++ b/frontend/src/app/main/ui.cljs
@@ -277,7 +277,7 @@
 
        :viewer
        (let [params   (get params :query)
-             index    (some-> (:index params) parse-long)
+             index    (some-> (rt/get-query-param params :index) parse-long)
              share-id (some-> (:share-id params) uuid/parse*)
              section  (or (some-> (:section params) keyword)
                           :interactions)
diff --git a/frontend/src/app/main/ui/auth/register.cljs b/frontend/src/app/main/ui/auth/register.cljs
index 3bd3fdf564..917b272dd9 100644
--- a/frontend/src/app/main/ui/auth/register.cljs
+++ b/frontend/src/app/main/ui/auth/register.cljs
@@ -276,6 +276,7 @@
         (mf/use-fn
          (mf/deps on-success-callback)
          (fn [params]
+           (cf/external-notify-register-success (:id params))
            (if (fn? on-success-callback)
              (on-success-callback (:email params))
 
diff --git a/frontend/src/app/main/ui/auth/verify_token.cljs b/frontend/src/app/main/ui/auth/verify_token.cljs
index 334303ade4..16e818e4b2 100644
--- a/frontend/src/app/main/ui/auth/verify_token.cljs
+++ b/frontend/src/app/main/ui/auth/verify_token.cljs
@@ -6,6 +6,7 @@
 
 (ns app.main.ui.auth.verify-token
   (:require
+   [app.config :as cf]
    [app.main.data.auth :as da]
    [app.main.data.common :as dcm]
    [app.main.data.notifications :as ntf]
@@ -25,6 +26,7 @@
 
 (defmethod handle-token :verify-email
   [data]
+  (cf/external-notify-register-success (:profile-id data))
   (let [msg (tr "dashboard.notifications.email-verified-successfully")]
     (ts/schedule 1000 #(st/emit! (ntf/success msg)))
     (st/emit! (da/login-from-token data))))
diff --git a/frontend/src/app/main/ui/dashboard/file_menu.cljs b/frontend/src/app/main/ui/dashboard/file_menu.cljs
index dfecbc779b..06f7b29c36 100644
--- a/frontend/src/app/main/ui/dashboard/file_menu.cljs
+++ b/frontend/src/app/main/ui/dashboard/file_menu.cljs
@@ -78,7 +78,8 @@
 
         current-team     (get teams current-team-id)
         other-teams      (remove #(= (:id %) current-team-id) (vals teams))
-        current-projects (remove #(= (:id %) (:project-id file))
+        file-project-ids (into #{} (map :project-id) files)
+        current-projects (remove #(contains? file-project-ids (:id %))
                                  (:projects current-team))
 
         on-new-tab
diff --git a/frontend/src/app/main/ui/ds/tooltip/tooltip.cljs b/frontend/src/app/main/ui/ds/tooltip/tooltip.cljs
index f2375f2aa8..5dca183533 100644
--- a/frontend/src/app/main/ui/ds/tooltip/tooltip.cljs
+++ b/frontend/src/app/main/ui/ds/tooltip/tooltip.cljs
@@ -160,7 +160,7 @@
 
         tooltip-ref (mf/use-ref nil)
 
-        container (hooks/use-portal-container)
+        container (hooks/use-portal-container :tooltip)
 
         id
         (d/nilv id internal-id)
diff --git a/frontend/src/app/main/ui/hooks.cljs b/frontend/src/app/main/ui/hooks.cljs
index 42560cd8fe..ae8ebd30d5 100644
--- a/frontend/src/app/main/ui/hooks.cljs
+++ b/frontend/src/app/main/ui/hooks.cljs
@@ -380,17 +380,35 @@
 
     state))
 
+(defn- get-or-create-portal-container
+  "Returns the singleton container div for the given category, creating
+  and appending it to document.body on first access."
+  [category]
+  (let [body (dom/get-body)
+        id   (str "portal-container-" category)]
+    (or (dom/query body (str "#" id))
+        (let [container (dom/create-element "div")]
+          (dom/set-attribute! container "id" id)
+          (dom/append-child! body container)
+          container))))
+
 (defn use-portal-container
-  "Creates a dedicated div container for React portals. The container
-  is appended to document.body on mount and removed on cleanup, preventing
-  removeChild race conditions when multiple portals target the same body."
-  []
-  (let [container (mf/use-memo #(dom/create-element "div"))]
-    (mf/with-effect []
-      (let [body (dom/get-body)]
-        (dom/append-child! body container)
-        #(dom/remove-child! body container)))
-    container))
+  "Returns a shared singleton container div for React portals, identified
+  by a logical category. Available categories:
+
+    :modal    — modal dialogs
+    :popup    — popups, dropdowns, context menus
+    :tooltip  — tooltips
+    :default  — general portal use (default)
+
+  All portals in the same category share one <div> on document.body,
+  keeping the DOM clean and avoiding removeChild race conditions."
+  ([]
+   (use-portal-container :default))
+  ([category]
+   (let [category (name category)]
+     (mf/with-memo [category]
+       (get-or-create-portal-container category)))))
 
 (defn use-dynamic-grid-item-width
   ([] (use-dynamic-grid-item-width nil))
diff --git a/frontend/src/app/main/ui/modal.cljs b/frontend/src/app/main/ui/modal.cljs
index 5df1cc3daa..6e9b1df7d4 100644
--- a/frontend/src/app/main/ui/modal.cljs
+++ b/frontend/src/app/main/ui/modal.cljs
@@ -84,7 +84,7 @@
 (mf/defc modal-container*
   {::mf/props :obj}
   []
-  (let [container (hooks/use-portal-container)]
+  (let [container (hooks/use-portal-container :modal)]
     (when-let [modal (mf/deref ref:modal)]
       (mf/portal
        (mf/html [:> modal-wrapper* {:data modal :key (dm/str (:id modal))}])
diff --git a/frontend/src/app/main/ui/workspace/tokens/management/context_menu.cljs b/frontend/src/app/main/ui/workspace/tokens/management/context_menu.cljs
index 0dd980f73f..8efa0ba66c 100644
--- a/frontend/src/app/main/ui/workspace/tokens/management/context_menu.cljs
+++ b/frontend/src/app/main/ui/workspace/tokens/management/context_menu.cljs
@@ -517,7 +517,7 @@
         dropdown-direction-change* (mf/use-ref 0)
         top                 (+ (get-in mdata [:position :y]) 5)
         left                (+ (get-in mdata [:position :x]) 5)
-        container           (hooks/use-portal-container)]
+        container           (hooks/use-portal-container :popup)]
 
     (mf/use-effect
      (mf/deps is-open?)
diff --git a/frontend/src/app/main/ui/workspace/tokens/management/node_context_menu.cljs b/frontend/src/app/main/ui/workspace/tokens/management/node_context_menu.cljs
index d37e628d02..f150240cf1 100644
--- a/frontend/src/app/main/ui/workspace/tokens/management/node_context_menu.cljs
+++ b/frontend/src/app/main/ui/workspace/tokens/management/node_context_menu.cljs
@@ -36,7 +36,7 @@
         dropdown-direction-change* (mf/use-ref 0)
         top                 (+ (get-in mdata [:position :y]) 5)
         left                (+ (get-in mdata [:position :x]) 5)
-        container           (hooks/use-portal-container)
+        container           (hooks/use-portal-container :popup)
 
         delete-node          (mf/use-fn
                               (mf/deps mdata)
diff --git a/frontend/src/app/main/ui/workspace/tokens/themes/theme_selector.cljs b/frontend/src/app/main/ui/workspace/tokens/themes/theme_selector.cljs
index a8687c9719..d688588e2f 100644
--- a/frontend/src/app/main/ui/workspace/tokens/themes/theme_selector.cljs
+++ b/frontend/src/app/main/ui/workspace/tokens/themes/theme_selector.cljs
@@ -114,7 +114,7 @@
                         :is-open? true
                         :rect rect))))))
 
-        container (hooks/use-portal-container)]
+        container (hooks/use-portal-container :popup)]
 
     [:div {:on-click on-open-dropdown
            :disabled (not can-edit?)
diff --git a/frontend/test/frontend_tests/main_errors_test.cljs b/frontend/test/frontend_tests/main_errors_test.cljs
new file mode 100644
index 0000000000..5dc1747658
--- /dev/null
+++ b/frontend/test/frontend_tests/main_errors_test.cljs
@@ -0,0 +1,136 @@
+;; This Source Code Form is subject to the terms of the Mozilla Public
+;; License, v. 2.0. If a copy of the MPL was not distributed with this
+;; file, You can obtain one at http://mozilla.org/MPL/2.0/.
+;;
+;; Copyright (c) KALEIDOS INC
+
+(ns frontend-tests.main-errors-test
+  "Unit tests for app.main.errors.
+
+  Tests cover:
+    - stale-asset-error?          – pure predicate
+    - exception->error-data       – pure transformer
+    - on-error re-entrancy guard  – prevents recursive invocations
+    - flash schedules async emit  – ntf/show is not emitted synchronously"
+  (:require
+   [app.main.errors :as errors]
+   [cljs.test :as t :include-macros true]
+   [potok.v2.core :as ptk]))
+
+;; ---------------------------------------------------------------------------
+;; stale-asset-error?
+;; ---------------------------------------------------------------------------
+
+(t/deftest stale-asset-error-nil
+  (t/testing "nil cause returns nil/falsy"
+    (t/is (not (errors/stale-asset-error? nil)))))
+
+(t/deftest stale-asset-error-keyword-cst-undefined
+  (t/testing "error with $cljs$cst$ and 'is undefined' is recognised"
+    (let [err (js/Error. "foo$cljs$cst$bar is undefined")]
+      (t/is (true? (boolean (errors/stale-asset-error? err)))))))
+
+(t/deftest stale-asset-error-keyword-cst-null
+  (t/testing "error with $cljs$cst$ and 'is null' is recognised"
+    (let [err (js/Error. "foo$cljs$cst$bar is null")]
+      (t/is (true? (boolean (errors/stale-asset-error? err)))))))
+
+(t/deftest stale-asset-error-protocol-dispatch-undefined
+  (t/testing "error with $cljs$core$I and 'Cannot read properties of undefined' is recognised"
+    (let [err (js/Error. "Cannot read properties of undefined (reading '$cljs$core$IFn$_invoke$arity$1$')")]
+      (t/is (true? (boolean (errors/stale-asset-error? err)))))))
+
+(t/deftest stale-asset-error-not-a-function
+  (t/testing "error with $cljs$cst$ and 'is not a function' is recognised"
+    (let [err (js/Error. "foo$cljs$cst$bar is not a function")]
+      (t/is (true? (boolean (errors/stale-asset-error? err)))))))
+
+(t/deftest stale-asset-error-unrelated-message
+  (t/testing "ordinary error without stale-asset signature is NOT recognised"
+    (let [err (js/Error. "Cannot read properties of undefined (reading 'foo')")]
+      (t/is (not (errors/stale-asset-error? err))))))
+
+(t/deftest stale-asset-error-only-cst-no-undefined
+  (t/testing "error with $cljs$cst$ but no undefined/null/not-a-function keyword is not recognised"
+    (let [err (js/Error. "foo$cljs$cst$bar exploded")]
+      (t/is (not (errors/stale-asset-error? err))))))
+
+;; ---------------------------------------------------------------------------
+;; exception->error-data
+;; ---------------------------------------------------------------------------
+
+(t/deftest exception->error-data-plain-error
+  (t/testing "plain JS Error is converted to a data map with :hint and ::instance"
+    (let [err  (js/Error. "something went wrong")
+          data (errors/exception->error-data err)]
+      (t/is (= "something went wrong" (:hint data)))
+      (t/is (identical? err (::errors/instance data))))))
+
+(t/deftest exception->error-data-ex-info
+  (t/testing "ex-info error preserves existing :hint and attaches ::instance"
+    (let [err  (ex-info "original" {:hint "my-hint" :type :network})
+          data (errors/exception->error-data err)]
+      (t/is (= "my-hint" (:hint data)))
+      (t/is (= :network (:type data)))
+      (t/is (identical? err (::errors/instance data))))))
+
+(t/deftest exception->error-data-ex-info-no-hint
+  (t/testing "ex-info without :hint falls back to ex-message"
+    (let [err  (ex-info "fallback message" {:type :validation})
+          data (errors/exception->error-data err)]
+      (t/is (= "fallback message" (:hint data))))))
+
+;; ---------------------------------------------------------------------------
+;; on-error dispatches to ptk/handle-error
+;;
+;; We use a dedicated test-only error type so we can add/remove a
+;; defmethod without touching the real handlers.
+;; ---------------------------------------------------------------------------
+
+(def ^:private test-handled (atom nil))
+
+(defmethod ptk/handle-error ::test-dispatch
+  [err]
+  (reset! test-handled err))
+
+(t/deftest on-error-dispatches-map-error
+  (t/testing "on-error dispatches a map error to ptk/handle-error using its :type"
+    (reset! test-handled nil)
+    (errors/on-error {:type ::test-dispatch :hint "hello"})
+    (t/is (= ::test-dispatch (:type @test-handled)))
+    (t/is (= "hello" (:hint @test-handled)))))
+
+(t/deftest on-error-wraps-exception-then-dispatches
+  (t/testing "on-error wraps a JS Error into error-data before dispatching"
+    (reset! test-handled nil)
+    (let [err (ex-info "wrapped" {:type ::test-dispatch})]
+      (errors/on-error err)
+      (t/is (= ::test-dispatch (:type @test-handled)))
+      (t/is (identical? err (::errors/instance @test-handled))))))
+
+;; ---------------------------------------------------------------------------
+;; on-error re-entrancy guard
+;;
+;; The guard is implemented via the `handling-error?` volatile inside
+;; app.main.errors.  We can verify its effect by registering a
+;; handle-error method that itself calls on-error and checking that
+;; only one invocation gets through.
+;; ---------------------------------------------------------------------------
+
+(def ^:private reentrant-call-count (atom 0))
+
+(defmethod ptk/handle-error ::test-reentrant
+  [_err]
+  (swap! reentrant-call-count inc)
+  ;; Simulate a secondary error inside the error handler
+  ;; (e.g. the notification emit itself throws).
+  ;; Without the re-entrancy guard this would recurse indefinitely.
+  (when (= 1 @reentrant-call-count)
+    (errors/on-error {:type ::test-reentrant :hint "secondary"})))
+
+(t/deftest on-error-reentrancy-guard-prevents-recursion
+  (t/testing "a second on-error call while handling an error is suppressed by the guard"
+    (reset! reentrant-call-count 0)
+    (errors/on-error {:type ::test-reentrant :hint "first"})
+    ;; The guard must have allowed only the first invocation through.
+    (t/is (= 1 @reentrant-call-count))))
diff --git a/frontend/test/frontend_tests/runner.cljs b/frontend/test/frontend_tests/runner.cljs
index 3cd38c12f0..003e68264c 100644
--- a/frontend/test/frontend_tests/runner.cljs
+++ b/frontend/test/frontend_tests/runner.cljs
@@ -14,6 +14,7 @@
    [frontend-tests.logic.frame-guides-test]
    [frontend-tests.logic.groups-test]
    [frontend-tests.logic.pasting-in-containers-test]
+   [frontend-tests.main-errors-test]
    [frontend-tests.plugins.context-shapes-test]
    [frontend-tests.svg-fills-test]
    [frontend-tests.tokens.import-export-test]
@@ -41,6 +42,7 @@
   (t/run-tests
    'frontend-tests.basic-shapes-test
    'frontend-tests.data.repo-test
+   'frontend-tests.main-errors-test
    'frontend-tests.data.viewer-test
    'frontend-tests.data.workspace-colors-test
    'frontend-tests.data.workspace-texts-test