NIP-87: Ecash Mint Discoverability

87.md

@@ -0,0 +1,142 @@
+NIP-87
+======
+
+Ecash Mint Discoverability
+--------------------------------
+
+`draft` `optional`
+
+This NIP describes `kind:38173`, `kind:38172` and `kind:38000`: a way to discover ecash mints, their capabilities, and people who recommend them.
+
+## Rationale
+
+Nostr's discoverability and transparent event interaction is one of its most interesting/novel mechanics.
+This NIP provides a simple way for users to discover ecash mints recommended by other users and to interact with them.
+
+### Parties involved
+
+There are three actors to this workflow:
+
+* An ecash mint operator, announces their mint and its capabilities.
+    * Publishes `kind:38173` or `kind:38172`, detailing how to connect to it and its capabilities.
+* user A, who recommends an ecash mint
+    * Publishes `kind:38000`
+* user B, who seeks a recommendation for an ecash mint
+    * Queries for `kind:38000` and, based on results, queries for `kind:38173`/`kind:38172`
+
+## Events
+
+### Recommendation event
+```json
+{
+  "kind": 38000,
+  "pubkey": <recommender-user-pubkey>,
+  "tags": [
+    ["k", "38173"],
+    ["d", "<d-identifier>"],
+    ["u", <recommended-fedimint-invite-code>],
+    ["a", "38173:fedimint-pubkey:<d-identifier>", "wss://relay1"]
+  ],
+  "content": "I trust this mint with my life"
+}
+```
+
+The recommendation event is a parameterized-replacable event so that a user can change edit their recommendation without creating a new event.
+
+The `d` tag in `kind:38000` is the `kind:38173`/`kind:38172` event identifier this event is recommending, if no event exists, the `d` tag can still be calculated from the mint's pubkey/id.
+The `k` tag is the kind number that corresponds to the event kind that the user is recommending, in this case `kind:38173` for fedimints and `kind:38172` for cashu mints.
+
+Optional `u` tags can be added to give a recommend way to connect to the mint.
+The value of the tag is the URL or invite code of the ecash mint.
+Multiple `u` tags can appear on the same `kind:38000`.
+
+`a` tags are used to point to the `kind:38173`/`kind:38172` event of the ecash mint.
+The first value of the tag is the `kind:38173`/`kind:38172` event identifier, the second value of the tag is a relay hint.
+This is used to correctly point to the mint's `kind:38173`/`kind:38172` event in case there are duplicates claiming to be the same mint.
+
+The content can be used to give a review.
+
+## Ecash Mint Information
+
+Cashu mints SHOULD publish `kind:38172` events to announce their capabilities and how to connect to them.
+
+For cashu mints, the `u` tag SHOULD be the URL to the cashu mint and it should list the nuts that the cashu mint supports.
+
+The `d` tag SHOULD be the mint's pubkey (found when querying `/v1/info`), this way users can query by pubkey and find the mint announcement.
+
+An `n` tag SHOULD be added to signify the network the cashu mint is on (either `mainnet`, `testnet`, `signet`, or `regtest`)
+
+```json
+{
+  "kind": 38172,
+  "pubkey": "<application-pubkey>",
+  "content": "<optional-kind:0-style-metadata>",
+  "tags": [
+    ["d", <cashu mint pubkey>],
+    ["u", "https://cashu.example.com"],
+    ["nuts", "1,2,3,4,5,6,7"],
+    ["n", "mainnet"]
+  ]
+}
+```
+
+Fedimints SHOULD publish `kind:38173` events to announce their capabilities and how to connect to them.
+
+For fedimints, it should list all known fedimint invite codes in `u` tags and it should list the modules it supports.
+
+The `d` tag SHOULD be the federation id, this way users can query by federation id and find the fedimint announcement.
+
+An `n` tag SHOULD be added to signify the network the fedimint is on (either `mainnet`, `testnet`, `signet`, or `regtest`)
+
+```json
+{
+  "kind": 38173,
+  "pubkey": "<application-pubkey>",
+  "content": "<optional-kind:0-style-metadata>",
+  "tags": [
+    ["d", <federation-id>],
+    ["u", "fed11abc.."],
+    ["u", "fed11xyz.."],
+    ["modules", "lightning,wallet,mint"],
+    ["n", "signet"]
+  ]
+}
+```
+
+* `content` is an optional `metadata`-like stringified JSON object, as described in NIP-01. This content is useful when the pubkey creating the `kind:38173` is not a normal user. If `content` is empty, the `kind:0` of the pubkey should be used to display mint information (e.g. name, picture, web, LUD16, etc.)
+
+## Example
+
+### User A recommends some mints
+User A might be a user of a cashu mint. Using a client, user A publishes an event recommending the cashu mint they use.
+
+```json
+{
+  "kind": 38000,
+  "tags": [
+    ["u", "fed11abc..", "fedimint"],
+    ["u", "https://cashu.example.com", "cashu"],
+    ["a", "38173:fedimint-pubkey:<d-identifier>", "wss://relay1", "fedimint"],
+    ["a", "38172:cashu-mint-pubkey:<d-identifier>", "wss://relay2", "cashu"]
+  ],
+  ...
+}
+```
+
+### User B finds a mint
+User B wants to use an ecash wallet, they need to find a mint.
+
+User B's wallet client queries for `kind:38000` events, looking for recommendations for ecash mints.
+
+```json
+["REQ", <id>, [{ "kinds": [38000], "authors": [<user>, <users-contact-list>], "#k": ["38173"] }]]
+```
+
+User B, who follows User A, sees that `kind:38000` event and tries to connect to the corresponding mints.
+
+### Alternative query bypassing `kind:38000`
+Alternatively, users might choose to query directly for `kind:38173` for an event kind. Clients SHOULD be careful doing this and use spam-prevention mechanisms or querying high-quality restricted relays to avoid directing users to malicious handlers.
+
+```json
+["REQ", <id>, [{ "kinds": [38173], "authors": [...] }]]
+```

README.md

@@ -74,6 +74,7 @@ They exist to document what may be implemented by [Nostr](https://github.com/nos
 - [NIP-75: Zap Goals](75.md)
 - [NIP-78: Application-specific data](78.md)
 - [NIP-84: Highlights](84.md)
+- [NIP-87: Ecash Mint Discoverability](87.md)
 - [NIP-89: Recommended Application Handlers](89.md)
 - [NIP-90: Data Vending Machines](90.md)
 - [NIP-92: Media Attachments](92.md)
@@ -139,6 +140,7 @@ They exist to document what may be implemented by [Nostr](https://github.com/nos
 | `10030`       | User emoji list            | [51](51.md)              |
 | `10096`       | File storage server list   | [96](96.md)              |
 | `13194`       | Wallet Info                | [47](47.md)              |
+| `18173`       | Ecash Mint Recommendation  | [87](87.md)              |
 | `21000`       | Lightning Pub RPC          | [Lightning.Pub][lnpub]   |
 | `22242`       | Client Authentication      | [42](42.md)              |
 | `23194`       | Wallet Request             | [47](47.md)              |
@@ -173,6 +175,8 @@ They exist to document what may be implemented by [Nostr](https://github.com/nos
 | `31925`       | Calendar Event RSVP        | [52](52.md)              |
 | `31989`       | Handler recommendation     | [89](89.md)              |
 | `31990`       | Handler information        | [89](89.md)              |
+| `38172`       | Cashu Mint Announcement    | [87](87.md)              |
+| `38173`       | Fedimint Announcement      | [87](87.md)              |
 | `34550`       | Community Definition       | [72](72.md)              |
 | `39000-9`     | Group metadata events      | [29](29.md)              |