diff --git a/WALLET.scratch.md b/WALLET.scratch.md
index b09e6989d..99dd8c26f 100644
--- a/WALLET.scratch.md
+++ b/WALLET.scratch.md
@@ -35,18 +35,17 @@ nixt:walt1
 ```
 
 ## Algos
-Insert an address
-1. send wallet an address that we KNOW is in the wallet
-2. include the address's index 
 
 Scan addresses. (map xpub (pair list list))
-outgoing wire is /scan/xpub/change/index
-- keep list of  whether we've heard back on an address `(list (unit used))`
+outgoing wire is /scan/xpub/change/idx
+- keep (jug cord idx) of xpub+chyg -> idx
 - every time we get a response
-  - insert the address into the wallet if it's used
-  - check whether (lent (murn l)) == max-gap
-  - if it does, run lien--if any used, continue
-  - if none used, the wallet is scanned.
+  - check whether idx in `scanning`--ignore if not (old response)
+  - insert the address into the wallet **if it's used**
+  - if used, update `has-used` for this xpub to be true
+  - delete idx from `scanning` jug
+  - check whether `scanning` is now empty
+  
 
 
 ## scratch code, refactor
diff --git a/sur/btc-wallet-store.hoon b/sur/btc-wallet-store.hoon
index 731e16ae7..8455a1f2e 100644
--- a/sur/btc-wallet-store.hoon
+++ b/sur/btc-wallet-store.hoon
@@ -25,6 +25,13 @@
 +$  wach  (map address addi)
 +$  scon  $~([max-index max-index] (pair idx idx))
 +$  wilt  _bip32
+::  scanning: maps xpub+chyg to set of indices.
+::            once it's full, we can check whether address in it were blank or not
+::  seen:     holds addresses whose scan results we've seen already
+::
++$  scanning  (jug cord idx)
++$  has-used  (map cord ?)
+::
 +$  action
   $%  [%add-wallet =xpub scan-to=(unit scon) max-gap=(unit @)]
       [%update-address a=address utxos=(set utxo)]