diff --git a/lexicons/space.notjack.thunderstorm.catalogDelta.json b/lexicons/space.notjack.thunderstorm.catalogDelta.json
index 6581ebd..2430961 100644
--- a/lexicons/space.notjack.thunderstorm.catalogDelta.json
+++ b/lexicons/space.notjack.thunderstorm.catalogDelta.json
@@ -8,7 +8,7 @@
       "key": "tid",
       "record": {
         "type": "object",
-        "required": ["preceding", "result"],
+        "required": ["preceding", "result", "packageChanges"],
         "properties": {
           "preceding": {
             "type": "string",
@@ -35,7 +35,7 @@
                 "contentsBefore": {
                   "type": "string",
                   "format": "at-uri",
-                  "description": "A reference to a space.notjack.thunderstorm.packageContents record containing the contents of this package before the delta's changes were applied to it, or null of the package didn't exist in the catalog beforehand."
+                  "description": "A reference to a space.notjack.thunderstorm.packageContents record containing the contents of this package before the delta's changes were applied to it, or null if the package didn't exist in the catalog beforehand."
                 },
                 "contentsAfter": {
                   "type": "string",
diff --git a/services/racksnaps-differ/README.md b/services/racksnaps-differ/README.md
index 9bfdac5..01b2e68 100644
--- a/services/racksnaps-differ/README.md
+++ b/services/racksnaps-differ/README.md
@@ -8,7 +8,7 @@ This service is allowed to interact with the following data sources:
 
 - https://racksnaps.defn.io/ (read-only)
 - at://{THUNDERSTORM_DID}/space.notjack.thunderstorm.catalogSnapshot (read-only)
-- at://{THUNDERSTORM_DID}/space.notjack.thunderstorm.catalogDelta (create-only)
+- at://{THUNDERSTORM_DID}/space.notjack.thunderstorm.catalogDelta (read, create)
 
 It can be configured via the following environment variables: