Collaborative event ownership

C1.md

@@ -0,0 +1,126 @@
+NIP-C1
+======
+
+Collaborative Ownership
+-----------------------
+
+`draft` `optional`
+
+This NIP defines a mechanism for multiple pubkeys to collaboratively maintain events.
+
+## Motivation
+
+Certain applications require shared ownership where:
+
+1. **Attribution matters**: Each collaborator signs with their own key
+2. **Dynamic membership**: Owners can be added or removed
+3. **Backwards compatibility**: Non-supporting clients see normal events
+
+## Specification
+
+### Collaborative Pointer Event
+
+An addressable event kind `39382` serves as a pointer to collaboratively-owned content:
+
+```jsonc
+{
+  "kind": 39382,
+  "pubkey": "<creator-pubkey>",
+  "tags": [
+    ["d", "<identifier>"],
+    ["k", "<target-kind>"],
+    ["p", "<owner-1-pubkey>"],
+    ["p", "<owner-2-pubkey>"],
+    ["p", "<owner-3-pubkey>"]
+  ],
+  "content": "",
+  "created_at": 1234567890
+}
+```
+
+#### Tag Definitions
+
+| Tag | Required | Description |
+|-----|----------|-------------|
+| `d` | Yes | Shared identifier for the collaborative content |
+| `k` | Yes | Target event kind (any kind) |
+| `p` | Yes | Owner pubkeys (one or more) |
+
+The creator's pubkey is implicitly an owner.
+
+### Target Events
+
+Any event kind MAY be a target of collaborative ownership. All target events:
+
+- MUST include a `d` tag matching the pointer's `d` tag
+- MUST include an `a` tag referencing the `39382` pointer event
+
+```jsonc
+{
+  "kind": <target-kind>,
+  "pubkey": "<owner-pubkey>",
+  "tags": [
+    ["d", "<identifier>"],
+    ["a", "39382:<pointer-creator-pubkey>:<identifier>"]
+  ],
+  "content": "..."
+}
+```
+
+### Resolution Algorithm
+
+To resolve the current state of collaboratively-owned content:
+
+1. Collect owners from the `39382` pointer's `p` tags (plus the pointer's pubkey)
+2. Query: `{"kinds": [<target-kind>], "authors": [<all-owners>], "#d": ["<identifier>"], "limit": 1}`
+3. Return the most recent event
+
+## Client Behavior
+
+### Co-Author Attribution
+
+Clients SHOULD NOT display co-author attribution for a target event unless:
+
+1. The event contains an `a` tag referencing a `39382` pointer event, **and**
+2. The event's author pubkey appears in that pointer's `p` tags (or is the pointer's creator)
+
+An event without a verifiable `a` tag backlink to a `39382` pointer MUST NOT be presented as collaboratively authored. This prevents spoofed co-authorship claims.
+
+## Example
+
+### Pointer Event
+
+```jsonc
+{
+  "kind": 39382,
+  "pubkey": "alice-pubkey",
+  "tags": [
+    ["d", "collaborative-guide"],
+    ["k", "30023"],
+    ["p", "bob-pubkey"],
+    ["p", "carol-pubkey"]
+  ],
+  "content": ""
+}
+```
+
+### Target Event (by any owner)
+
+```jsonc
+{
+  "kind": 30023,
+  "pubkey": "bob-pubkey",
+  "tags": [
+    ["d", "collaborative-guide"],
+    ["title", "A Collaborative Guide"],
+    ["a", "39382:alice-pubkey:collaborative-guide"]
+  ],
+  "content": "..."
+}
+```
+
+### Client Resolution
+
+1. Client receives the `39382` pointer
+2. Owners: `[alice, bob, carol]`, target kind: `30023`
+3. Queries: `{"kinds": [30023], "authors": ["alice", "bob", "carol"], "#d": ["collaborative-guide"], "limit": 1}`

README.md

@@ -109,6 +109,7 @@ They exist to document what may be implemented by [Nostr](https://github.com/nos
 - [NIP-B7: Blossom](B7.md)
 - [NIP-BE: Nostr BLE Communications Protocol](BE.md)
 - [NIP-C0: Code Snippets](C0.md)
+- [NIP-C1: Collaborative Ownership](C1.md)
 - [NIP-C7: Chats](C7.md)
 - [NIP-EE: E2EE Messaging using MLS Protocol](EE.md) --- **unrecommended**: superseded by the [Marmot Protocol](https://github.com/marmot-protocol/marmot)
 
@@ -294,6 +295,7 @@ They exist to document what may be implemented by [Nostr](https://github.com/nos
 | `39000-9`     | Group metadata events           | [29](29.md)                            |
 | `39089`       | Starter packs                   | [51](51.md)                            |
 | `39092`       | Media starter packs             | [51](51.md)                            |
+| `39382`       | Collaborative Pointer           | [C1](C1.md)                            |
 | `39701`       | Web bookmarks                   | [B0](B0.md)                            |
 
 [NUD: Custom Feeds]: https://wikifreedia.xyz/cip-01/