Remove Req-Res and update for single market maker use case

- Bob initiate swap with BTC Amount
- Alice acks with approx. xmr amount
- Rework terminology, make a difference between negotiations and
execution setup
- Remove request response channels in favor of one shots
- Give exact amount to Bob once assets are locked

docs/sequence.puml

@@ -4,52 +4,53 @@ actor Bob
 Actor Alice
 database Monero
 
+group Negotiation
+
     Bob --> Alice: Establish connection
 
     group Request Response Channel
-    Bob -> Alice: Request Amounts
-    note left: Btc Amount
+        Bob -> Alice: Swap request
+        note left: Btc Amount\naddress hints
+        note right: Alice stores peer id & address hints\nto contact Bob
 
-    Alice --> Bob: Send Amounts
-    note right: Btc & Xmr Amounts
+        Alice --> Bob: Swap response
+        note right: ACK or NACK\n Approx. XMR amount
+    end
 end
 
-group Request Response Channel
+group Execution Setup
+    group Phase 0 [Messages can be exchanged in any order]
         Bob -> Alice: bob::Message0
         note left: Pubkeys\ndleq proof s_b\nxmr viewkey v_b\nbtc refund addr
 
-    Alice --> Bob: alice::Message0
+        Alice -> Bob: alice::Message0
         note right: Pubkeys\ndleq proof s_a\nxmr view key v_a\nbtc redeem addr\nbtc punish addr
     end
 
-group Request Response Channel
-    Bob -> Alice: bob::Message1
-    note left: btc lock tx
+    group Phase 1 [Messages must be exchanged in the given order]
 
-    Alice --> Bob: alice::Message1
-    note right: cancel tx sig\nrefund tx enc sig S_b
+        Bob -> Alice: bob::Message1
+        note left: unsigned btc lock tx
+
+        Alice -> Bob: alice::Message1
+        note right: btc cancel tx sig\nbtc refund tx enc sig S_b
+
+        Bob -> Alice: bob::Message2
+        note left: btc punish tx sig\nbtc cancel tx sig
+
+    end
 end
 
-group Request Response Channel
-    Bob -> Alice: bob::Message2
-    note left: punish tx sig\ncancel tx sig
-
-== Negotiated ==
-
+group Execution
     Bob ->> Bitcoin: Lock
 
     Alice ->> Monero: Lock
 
-    Alice --> Bob: alice::Message2
-    note right: xmr lock tx transfer proof
-end
+    Alice -> Bob: alice::Message2
+    note right: Exact xmr amount\nzxmr lock tx transfer proof\nThis can be removed if Bob watches the blockchain.
 
-group Request Response Channel
     Bob -> Alice: bob::Message3
     note left: redeem tx enc sig S_a
-    Alice --> Bob: alice::Message3
-    note right: Empty
-end
 
     Alice ->> Bitcoin: Redeem
 
@@ -58,5 +59,6 @@ end
     Bob -> Bob: Extract s_a
 
     Bob ->> Monero: Redeem
+end
 
 @enduml