From 62f0b14ae81fd062bb84791bca698b29f6b573a3 Mon Sep 17 00:00:00 2001
From: Rob Woodgate <robwoodgate@users.noreply.github.com>
Date: Fri, 31 Oct 2025 13:59:35 +0000
Subject: [PATCH] Added base "unit" tag to NutZap kind:9321 event (#1915)

---
 60.md | 7 +++++++
 61.md | 3 +++
 2 files changed, 10 insertions(+)

diff --git a/60.md b/60.md
index 4b744189..8c836ac0 100644
--- a/60.md
+++ b/60.md
@@ -50,6 +50,7 @@ There can be multiple `kind:7375` events for the same mint, and multiple proofs
     "kind": 7375,
     "content": nip44_encrypt({
         "mint": "https://stablenut.umint.cash",
+        "unit": "sat",
         "proofs": [
             // one or more proofs in the default cashu format
             {
@@ -69,6 +70,7 @@ There can be multiple `kind:7375` events for the same mint, and multiple proofs
  * `.content` is a [NIP-44](44.md) encrypted payload:
    * `mint`: The mint the proofs belong to.
    * `proofs`: unencoded proofs
+   * `unit` the base unit the proofs are denominated in (eg: `sat`, `usd`, `eur`). Default: `sat` if omitted.
    * `del`: token-ids that were destroyed by the creation of this token. This assists with state transitions.
 
 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).
@@ -84,6 +86,7 @@ Clients SHOULD publish `kind:7376` events to create a transaction history when t
     "content": nip44_encrypt([
         [ "direction", "in" ], // in = received, out = sent
         [ "amount", "1" ],
+        [ "unit", "sat" ],
         [ "e", "<event-id-of-created-token>", "", "created" ]
     ]),
     "tags": [
@@ -93,6 +96,7 @@ Clients SHOULD publish `kind:7376` events to create a transaction history when t
 ```
 
 * `direction` - The direction of the transaction; `in` for received funds, `out` for sent funds.
+* `unit` the base unit of the amount (eg: `sat`, `usd`, `eur`). Default: `sat` if omitted.
 
 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.
@@ -121,6 +125,7 @@ If Alice spends 4 sats from this token event
     "id": "event-id-1",
     "content": nip44_encrypt({
         "mint": "https://stablenut.umint.cash",
+        "unit": "sat",
         "proofs": [
             { "id": "1", "amount": 1 },
             { "id": "2", "amount": 2 },
@@ -140,6 +145,7 @@ Her client:
     "id": "event-id-2",
     "content": nip44_encrypt({
         "mint": "https://stablenut.umint.cash",
+        "unit": "sat",
         "proofs": [
             { "id": "1", "amount": 1 },
             { "id": "2", "amount": 2 },
@@ -159,6 +165,7 @@ Her client:
     "content": nip44_encrypt([
         [ "direction", "out" ],
         [ "amount", "4" ],
+        [ "unit", "sat" ],
         [ "e", "<event-id-1>", "", "destroyed" ],
         [ "e", "<event-id-2>", "", "created" ],
     ]),
diff --git a/61.md b/61.md
index 5ef7f680..5842d6b3 100644
--- a/61.md
+++ b/61.md
@@ -51,6 +51,7 @@ Clients MUST prefix the public key they P2PK-lock with `"02"` (for nostr<>cashu
     "pubkey": "<sender-pubkey>",
     "tags": [
         [ "proof", "{\"amount\":1,\"C\":\"02277c66191736eb72fce9d975d08e3191f8f96afb73ab1eec37e4465683066d3f\",\"id\":\"000a93d6f8a1d2c4\",\"secret\":\"[\\\"P2PK\\\",{\\\"nonce\\\":\\\"b00bdd0467b0090a25bdf2d2f0d45ac4e355c482c1418350f273a04fedaaee83\\\",\\\"data\\\":\\\"02eaee8939e3565e48cc62967e2fde9d8e2a4b3ec0081f29eceff5c64ef10ac1ed\\\"}]\"}" ],
+        [ "unit", "sat" ],
         [ "u", "https://stablenut.umint.cash" ],
         [ "e", "<nutzapped-event-id>", "<relay-hint>" ],
         [ "k", "<nutzapped-kind>"],
@@ -62,6 +63,7 @@ Clients MUST prefix the public key they P2PK-lock with `"02"` (for nostr<>cashu
 * `.content` is an optional comment for the nutzap
 * `.tags`:
   * `proof` is one or more proofs P2PK-locked to the public key the recipient specified in their `kind:10019` event and including a DLEQ proof.
+  * `unit` the base unit the proofs are denominated in (eg: `sat`, `usd`, `eur`). Default: `sat` if omitted.
   * `u` is the mint the URL of the mint EXACTLY as specified by the recipient's `kind:10019`.
   * `p` is the Nostr identity public key of nutzap recipient.
   * `e` is the event that is being nutzapped, if any.
@@ -95,6 +97,7 @@ Multiple `kind:9321` events can be tagged in the same `kind:7376` event.
     "content": nip44_encrypt([
         [ "direction", "in" ], // in = received, out = sent
         [ "amount", "1" ],
+        [ "unit", "sat" ],
         [ "e", "<7375-event-id>", "<relay-hint>", "created" ] // new token event that was created
     ]),
     "tags": [