nip60/61 updates and simplifications (#1730)

Co-authored-by: Tiago Balas <eskema23@gmail.com>

1 files changed, 36 insertions, 62 deletions

diff --git a/60.md b/60.md
index 69db44f..87449d2 100644
--- a/60.md
+++ b/60.md
@@ -1,5 +1,9 @@
-# NIP-60
-## Cashu Wallet
+NIP-60
+======
+
+Cashu Wallets
+-------------
+
 `draft` `optional`
 
 This NIP defines the operations of a cashu-based wallet.
@@ -13,48 +17,28 @@ The purpose of this NIP is:
 This NIP doesn't deal with users' *receiving* money from someone else, it's just to keep state of the user's wallet.
 
 # High-level flow
-1. A user has a `kind:37375` event that represents a wallet.
+1. A user has a `kind:17375` event that represents a wallet.
 2. A user has `kind:7375` events that represent the unspent proofs of the wallet. -- The proofs are encrypted with the user's private key.
 3. A user has `kind:7376` events that represent the spending history of the wallet -- This history is for informational purposes only and is completely optional.
 
 ## Wallet Event
 ```jsonc
 {
-    "kind": 37375,
+    "kind": 17375,
     "content": nip44_encrypt([
-        [ "balance", "100", "sat" ],
-        [ "privkey", "hexkey" ] // explained in NIP-61
-    ]),
-    "tags": [
-        [ "d", "my-wallet" ],
+        [ "privkey", "hexkey" ],
         [ "mint", "https://mint1" ],
-        [ "mint", "https://mint2" ],
-        [ "mint", "https://mint3" ],
-        [ "name", "my shitposting wallet" ],
-        [ "unit", "sat" ],
-        [ "description", "a wallet for my day-to-day shitposting" ],
-        [ "relay", "wss://relay1" ],
-        [ "relay", "wss://relay2" ],
-    ]
+        [ "mint", "https://mint2" ]
+    ]),
+    "tags": []
 }
 ```
 
-The wallet event is an addressable event `kind:37375`.
+The wallet event is an replaceable event `kind:17375`.
 
 Tags:
-* `d` - wallet ID.
 * `mint` - Mint(s) this wallet uses -- there MUST be one or more mint tags.
-* `relay` - Relays where the wallet and related events can be found. -- one or more relays SHOULD be specified. If missing, clients should follow [NIP-65](65.md).
-* `unit` - Base unit of the wallet (e.g. "sat", "usd", etc).
-* `name` - Optional human-readable name for the wallet.
-* `description` - Optional human-readable description of the wallet.
-* `balance` - Optional best-effort balance of the wallet that can serve as a placeholder while an accurate balance is computed from fetching all unspent proofs.
-* `privkey` - Private key used to unlock P2PK ecash. MUST be stored encrypted in the `.content` field. **This is a different private key exclusively used for the wallet, not associated in any way to the user's nostr private key** -- This is only used when receiving funds from others, described in NIP-61.
-
-Any tag, other than the `d` tag, can be [NIP-44](44.md) encrypted into the `.content` field.
-
-### Deleting a wallet event
-Due to addressable event being hard to delete, if a user wants to delete a wallet, they should empty the event and keep just the `d` identifier and add a `deleted` tag.
+* `privkey` - Private key used to unlock P2PK ecash. MUST be stored encrypted in the `.content` field. **This is a different private key exclusively used for the wallet, not associated in any way to the user's Nostr private key** -- This is only used for receiving [NIP-61](61.md) nutzaps.
 
 ## Token Event
 Token events are used to record unspent proofs.
@@ -67,6 +51,7 @@ There can be multiple `kind:7375` events for the same mint, and multiple proofs
     "content": nip44_encrypt({
         "mint": "https://stablenut.umint.cash",
         "proofs": [
+            // one or more proofs in the default cashu format
             {
                 "id": "005c2502034d4f12",
                 "amount": 1,
@@ -74,23 +59,21 @@ There can be multiple `kind:7375` events for the same mint, and multiple proofs
                 "C": "0241d98a8197ef238a192d47edf191a9de78b657308937b4f7dd0aa53beae72c46"
             }
         ],
-        // tokens that were destroyed in the creation of this token
-        "del": [ "token-id-1" ]
+        // tokens that were destroyed in the creation of this token (helps on wallet state transitions)
+        "del": [ "token-event-id-1", "token-event-id-2" ]
     }),
-    "tags": [
-        [ "a", "37375:<pubkey>:my-wallet" ]
-    ]
+    "tags": []
 }
 ```
 
- * `a` an optional tag linking the token to a specific wallet.
- * `.content` is a [[NIP-44]] encrypted payload:
+ * `.content` is a [NIP-44](44.md) encrypted payload:
    * `mint`: The mint the proofs belong to.
    * `proofs`: unecoded proofs
    * `del`: token-ids that were destroyed by the creation of this token. This assists with state transitions.
 
-### Spending proofs
-When one or more proofs of a token are spent, the token event should be [NIP-09](09.md)-deleted and, if some proofs are unspent from the same token event, a new token event should be created rolling over the unspent proofs and adding any change outputs to the new token event.
+When one or more proofs of a token are spent, the token event should be [NIP-09](09.md)-deleted and, if some proofs are unspent from the same token event, a new token event should be created rolling over the unspent proofs and adding any change outputs to the new token event (the change output should include a `del` field).
+
+The `kind:5` _delete event_ created in the [NIP-09](09.md) process MUST have a tag `["k", "7375"]` to allow easy filtering by clients interested in state transitions.
 
 ## Spending History Event
 Clients SHOULD publish `kind:7376` events to create a transaction history when their balance changes.
@@ -100,17 +83,16 @@ Clients SHOULD publish `kind:7376` events to create a transaction history when t
     "kind": 7376,
     "content": nip44_encrypt([
         [ "direction", "in" ], // in = received, out = sent
-        [ "amount", "1", "sat" ],
-        [ "e", "<event-id-of-created-token>", "<relay-hint>", "created" ],
+        [ "amount", "1" ],
+        [ "e", "<event-id-of-created-token>", "", "created" ]
     ]),
     "tags": [
-        [ "a", "37375:<pubkey>:my-wallet" ],
+        [ "e", "<event-id-of-created-token>", "", "redeemed" ]
     ]
 }
 ```
 
 * `direction` - The direction of the transaction; `in` for received funds, `out` for sent funds.
-* `a` - The wallet the transaction is related to.
 
 Clients MUST add `e` tags to create references of destroyed and created token events along with the marker of the meaning of the tag:
 * `created` - A new token event was created.
@@ -119,7 +101,7 @@ Clients MUST add `e` tags to create references of destroyed and created token ev
 
 All tags can be [NIP-44](44.md) encrypted. Clients SHOULD leave `e` tags with a `redeemed` marker unencrypted.
 
-Multiple `e` tags can be added to a `kind:7376` event.
+Multiple `e` tags can be added, and should be encrypted, except for tags with the `redeemed` marker.
 
 # Flow
 A client that wants to check for user's wallets information starts by fetching `kind:10019` events from the user's relays, if no event is found, it should fall back to using the user's [NIP-65](65.md) relays.
@@ -127,10 +109,9 @@ A client that wants to check for user's wallets information starts by fetching `
 ## Fetch wallet and token list
 From those relays, the client should fetch wallet and token events.
 
-`"kinds": [37375, 7375], "authors": ["<my-pubkey>"]`
+`"kinds": [17375, 7375], "authors": ["<my-pubkey>"]`
 
 ## Fetch proofs
-While the client is fetching (and perhaps validating) proofs it can use the optional `balance` tag of the wallet event to display a estimate of the balance of the wallet.
 
 ## Spending token
 If Alice spends 4 sats from this token event
@@ -147,9 +128,7 @@ If Alice spends 4 sats from this token event
             { "id": "4", "amount": 8 },
         ]
     }),
-    "tags": [
-        [ "a", "37375:<pubkey>:my-wallet" ]
-    ]
+    "tags": []
 }
 ```
 
@@ -168,9 +147,7 @@ Her client:
         ],
         "del": [ "event-id-1" ]
     }),
-    "tags": [
-        [ "a", "37375:<pubkey>:my-wallet" ]
-    ]
+    "tags": []
 }
 ```
 * MUST delete event `event-id-1`
@@ -181,20 +158,18 @@ Her client:
     "kind": 7376,
     "content": nip44_encrypt([
         [ "direction", "out" ],
-        [ "amount", "4", "sats" ],
-        [ "e", "<event-id-1>", "<relay-hint>", "destroyed" ],
-        [ "e", "<event-id-2>", "<relay-hint>", "created" ],
+        [ "amount", "4" ],
+        [ "e", "<event-id-1>", "", "destroyed" ],
+        [ "e", "<event-id-2>", "", "created" ],
     ]),
-    "tags": [
-        [ "a", "37375:<pubkey>:my-wallet" ],
-    ]
+    "tags": []
 }
 ```
 
 ## Redeeming a quote (optional)
-When creating a quote at a mint, an event can be used to keep the state of the quote ID, which will be used to check when the quote has been paid. These events should be created with an expiration tag [NIP-40](40.md) matching the expiration of the bolt11 received from the mint; this signals to relays when they can safely discard these events.
+When creating a quote at a mint, an event can be used to keep the state of the quote ID, which will be used to check when the quote has been paid. These events should be created with an expiration tag [NIP-40](40.md) of 2 weeks (which is around the maximum amount of time a Lightning payment may be in-flight).
 
-Application developers are encouraged to use local state when possible and only publish this event when it makes sense in the context of their application.
+However, application developers SHOULD use local state when possible and only publish this event when it makes sense in the context of their application.
 
 ```jsonc
 {
@@ -202,8 +177,7 @@ Application developers are encouraged to use local state when possible and only
     "content": nip44_encrypt("quote-id"),
     "tags": [
         [ "expiration", "<expiration-timestamp>" ],
-        [ "mint", "<mint-url>" ],
-        [ "a", "37375:<pubkey>:my-wallet" ]
+        [ "mint", "<mint-url>" ]
     ]
 }
 ```