Add cw4 hooks

contracts/cw3-flex-multisig/README.md

@@ -29,10 +29,16 @@ with the desired member set. For now, this only is supported by
 (TODO). 
 
 If you create a `cw4-group` contract and want a multisig to be able
-to modify it's own group, set the admin as your personal key, then init the
-multisig pointing to the group, then modify the admin of the group to point
-back to the multisig. This is the current practice to create such circular
-dependencies (TODO: document better).
+to modify it's own group, do the following in multiple transactions:
+
+  * init cw4-group, with your personal key as admin
+  * init a multisig pointing to the group
+  * TODO: `AddHook{multisig}` on the group contract 
+  * `UpdateAdmin{multisig}` on the group contract
+
+This is the current practice to create such circular dependencies,
+and depends on an external driver (hard to impossible to script such a
+self-deploying contract on-chain). (TODO: document better).
 
 When creating the multisig, you must set the required weight to pass a vote
 as well as the max/default voting period. (TODO: allow more threshold types) 

contracts/cw4-group/schema/handle_msg.json

@@ -55,6 +55,46 @@
           }
         }
       }
+    },
+    {
+      "description": "Add a new hook to be informed of all membership changes. Must be called by Admin",
+      "type": "object",
+      "required": [
+        "add_hook"
+      ],
+      "properties": {
+        "add_hook": {
+          "type": "object",
+          "required": [
+            "addr"
+          ],
+          "properties": {
+            "addr": {
+              "$ref": "#/definitions/HumanAddr"
+            }
+          }
+        }
+      }
+    },
+    {
+      "description": "Remove a hook. Must be called by Admin",
+      "type": "object",
+      "required": [
+        "remove_hook"
+      ],
+      "properties": {
+        "remove_hook": {
+          "type": "object",
+          "required": [
+            "addr"
+          ],
+          "properties": {
+            "addr": {
+              "$ref": "#/definitions/HumanAddr"
+            }
+          }
+        }
+      }
     }
   ],
   "definitions": {

contracts/cw4-group/schema/query_msg.json

@@ -77,6 +77,18 @@
           }
         }
       }
+    },
+    {
+      "description": "Shows all registered hooks. Returns HooksResponse.",
+      "type": "object",
+      "required": [
+        "hooks"
+      ],
+      "properties": {
+        "hooks": {
+          "type": "object"
+        }
+      }
     }
   ],
   "definitions": {