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}`