diff --git a/common/src/app/common/files/changes.cljc b/common/src/app/common/files/changes.cljc
index f30701ef6..a2d8f4fda 100644
--- a/common/src/app/common/files/changes.cljc
+++ b/common/src/app/common/files/changes.cljc
@@ -154,12 +154,12 @@
     [:add-color
      [:map {:title "AddColorChange"}
       [:type [:= :add-color]]
-      [:color :any]]]
+      [:color ::ctc/color]]]
 
     [:mod-color
      [:map {:title "ModColorChange"}
       [:type [:= :mod-color]]
-      [:color :any]]]
+      [:color ::ctc/color]]]
 
     [:del-color
      [:map {:title "DelColorChange"}
diff --git a/common/src/app/common/schema.cljc b/common/src/app/common/schema.cljc
index b1e743f64..fcb3f1107 100644
--- a/common/src/app/common/schema.cljc
+++ b/common/src/app/common/schema.cljc
@@ -619,20 +619,27 @@
                  {:title "contains"
                   :description "contains predicate"}}))})
 
-(define! ::inst
+(def type:inst
   {:type ::inst
    :pred inst?
    :type-properties
    {:title "inst"
     :description "Satisfies Inst protocol"
-    :error/message "expected to be number in safe range"
+    :error/message "should be an instant"
     :gen/gen (->> (sg/small-int)
-                  (sg/fmap (fn [v] (tm/instant v))))
-    ::oapi/type "number"
-    ::oapi/format "int64"}})
+                  (sg/fmap (fn [v] (tm/parse-instant v))))
 
-(define! ::fn
-  [:schema fn?])
+    :decode/string tm/parse-instant
+    :encode/string tm/format-instant
+    :decode/json tm/parse-instant
+    :encode/json tm/format-instant
+    ::oapi/type "string"
+    ::oapi/format "iso"}})
+
+(register! ::inst type:inst)
+
+(register! ::fn
+           [:schema fn?])
 
 (define! ::word-string
   {:type ::word-string
diff --git a/common/src/app/common/time.cljc b/common/src/app/common/time.cljc
index 6cd8601d6..45e130deb 100644
--- a/common/src/app/common/time.cljc
+++ b/common/src/app/common/time.cljc
@@ -12,6 +12,7 @@
       ["luxon" :as lxn])
      :clj
      (:import
+      java.time.format.DateTimeFormatter
       java.time.Instant
       java.time.Duration)))
 
@@ -26,10 +27,29 @@
   #?(:clj (Instant/now)
      :cljs (.local ^js DateTime)))
 
-(defn instant
+(defn instant?
+  [o]
+  #?(:clj (instance? Instant o)
+     :cljs (instance? DateTime o)))
+
+(defn parse-instant
   [s]
-  #?(:clj  (Instant/ofEpochMilli s)
-     :cljs (.fromMillis ^js DateTime s #js {:zone "local" :setZone false})))
+  (cond
+    (instant? s)
+    s
+
+    (int? s)
+    #?(:clj  (Instant/ofEpochMilli s)
+       :cljs (.fromMillis ^js DateTime s #js {:zone "local" :setZone false}))
+
+    (string? s)
+    #?(:clj (Instant/parse s)
+       :cljs (.fromISO ^js DateTime s))))
+
+(defn format-instant
+  [v]
+  #?(:clj (.format DateTimeFormatter/ISO_INSTANT ^Instant v)
+     :cljs (.toISO ^js v)))
 
 #?(:cljs
    (extend-protocol IComparable