NIP-C1
======

Collaborative Ownership
-----------------------

`draft` `optional`

This NIP defines a mechanism for multiple pubkeys to collaboratively maintain addressable events while preserving backwards compatibility.

## 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

A new addressable event kind `39382` serves as a pointer to collaboratively-owned content:

```jsonc
{
  "kind": 39382,
  "pubkey": "<creator-pubkey>",
  "tags": [
    ["d", "<target-kind>-<slug>"],
    ["k", "<target-kind>"],
    ["p", "<owner-1-pubkey>"],
    ["p", "<owner-2-pubkey>"],
    ["p", "<owner-3-pubkey>"],
    ["relay", "wss://relay1.example.com"],
    ["relay", "wss://relay2.example.com"]
  ],
  "content": "",
  "created_at": 1234567890
}
```

#### Tag Definitions

| Tag | Required | Description |
|-----|----------|-------------|
| `d` | Yes | `<target-kind>-<slug>` - prevents collisions across kinds |
| `k` | Yes | Target event kind (avoids string parsing of `d` tag) |
| `p` | Yes | Owner pubkeys (one or more) |
| `relay` | No | Relay hints; if absent, use NIP-65 outbox model |

### Resolution Algorithm

To resolve the current state of collaboratively-owned content:

1. Parse the `39382` pointer event to extract owners (`p` tags) and target kind (`k` tag)
2. Extract the slug from the `d` tag (everything after the first `-`)
3. Query: `{"kinds": [<target-kind>], "authors": [<all-owners>], "#d": ["<slug>"], "limit": 1}`
4. Use `relay` tags if present; otherwise fall back to NIP-65 outbox relays
5. Return the event with the highest `created_at`

### Back-Reference (Optional)

Target events MAY include an `a` tag pointing to the `39382` pointer:

```jsonc
{
  "kind": 30023,
  "tags": [
    ["d", "my-article"],
    ["a", "39382:<pointer-creator-pubkey>:30023-my-article"]
  ]
}
```

This enables clients to discover that an event is part of a collaborative set.

## Example

### Pointer Event

```jsonc
{
  "kind": 39382,
  "pubkey": "alice-pubkey",
  "tags": [
    ["d", "30023-collaborative-guide"],
    ["k", "30023"],
    ["p", "alice-pubkey"],
    ["p", "bob-pubkey"],
    ["p", "carol-pubkey"],
    ["relay", "wss://relay.example.com"]
  ],
  "content": ""
}
```

### Target Article (by any owner)

```jsonc
{
  "kind": 30023,
  "pubkey": "bob-pubkey",
  "tags": [
    ["d", "collaborative-guide"],
    ["title", "A Collaborative Guide"],
    ["a", "39382:alice-pubkey:30023-collaborative-guide"]
  ],
  "content": "..."
}
```

### Client Resolution

1. Client receives `naddr` for the `39382` pointer
2. Parses owners: `[alice, bob, carol]`
3. Queries: `{"kinds": [30023], "authors": ["alice", "bob", "carol"], "#d": ["collaborative-guide"], "limit": 1}`
4. Returns most recent version regardless of which owner published it