document a plan for what the bot should look like

README.md

@@ -13,3 +13,32 @@ its goals are (in order of importance):
 5. optional reminders for outstanding debts.
 
 but so far, :B:illBöt achieves exactly 0 of these 🙃
+
+
+## Plan (UX)
+
+contingent upon what the Matrix/Appservice protocol and servers make available,
+below is an example of how this bot might work:
+
+1. open a payment channel with some other individual, if you & he have no history of transactions.
+- DM @billbot:uninsane.org with a message in format:
+        > `!transact @user:host [...]`
+- the billbot will create a room with itself, you, and all listed users.
+
+2. in this room, any user may post a message of the format
+> `!request @user:host [...] $NNN.MM`
+- the bot will post in the group a message to acknowledge each transfer:
+        > @user:host owes @other:host $NNN.MM
+
+3. request to see your position(s):
+> `!position [@user:host [...]]`
+- the bot will post your position.
+- you can initiate this from _any_ DM involving the bot.
+  so other parties don't *need* to see the bot's response, but still can, if you send this message to the group.
+
+4. mark a debt as paid:
+> `!sent @user:host $NNN.MM`
+- bot will post in the same room:
+        > @user:host paid @other:host $NNN.MM
+- maybe state the remaining position?
+        > @user:host now owes $other:host $X.YY