use select in with block and update with join back in order to retain lateral joins in the update

database/upgrade_scripts/001.extract_schemas.sql

@@ -1,26 +1,9 @@
-UPDATE
-    tps.srce
-SET
-    defn =  
-            --delete "schemas" from existing json and tack on revamped layout
-            jsonb_pretty((defn - 'schemas')||
-            --rebuild the schemas key value from below
-            jsonb_build_object(
-                'schemas'
-                --aggregate all the new key values for a single soure
-                ,jsonb_agg(
-                    --combine a new key 'name' with the columns for that name
-                    jsonb_build_object('name',k)||jsonb_build_object('columns',v)
-                )
-            ))
-
-
----------------select statement test-----------------------
-/*
+WITH
+mod AS (
 SELECT 
     srce
-    ,jsonb_pretty(defn)
-    ,jsonb_pretty((defn - 'schemas')||
+    ,jsonb_pretty(defn) orig
+    ,(defn - 'schemas')||
     --rebuild the schemas key value from below
     jsonb_build_object(
         'schemas'
@@ -29,11 +12,19 @@ SELECT
             --combine a new key 'name' with the columns for that name
             jsonb_build_object('name',k)||jsonb_build_object('columns',v)
         )
-    ))
+    ) rebuild
 FROM 
     tps.srce
     LEFT JOIN LATERAL jsonb_each(defn->'schemas') WITH ORDINALITY je(k,v, rn) ON TRUE
 GROUP BY
     srce
     ,defn
-*/
+)
+UPDATE
+    tps.srce s
+SET
+    defn = rebuild
+FROM
+    mod
+WHERE
+    mod.srce = s.srce