buzz/docs/nips/NIP-CL.md

NIP-CL

Channel Identity and Discovery

draft optional relay

This NIP adds identity facts to the relay-signed NIP-29 channel-state events (kinds 39000–39002). With these facts, a client can find channels with ordinary NIP-01 filters. It needs no new filter key and no relay-specific API.

Motivation

Plugins and agents often create a channel for their own use and must find it again later, for example "the config channel that this agent created". With plain NIP-29, a client cannot:

• tell who created a channel;
• read the channel type from any event except kind:39000; or
• tell which of two channels is older. The created_at of a kind:39000 event is the time of the last edit, not the time of creation.

A client also cannot mark its own channels so that it can find them again. Channel labels (below) do this.

Channel identity tags

On every channel-state event that the relay signs, the relay MUST put these tags in this order, before any other t or P tag:

1. ["t", <channel type>], for example stream, forum, dm, workflow.
2. ["t", <label>] for each channel label, in stored order (see Channel labels).
3. ["P", <creator public key, hex>].

kind:39000 also carries ["created_at", <unix seconds>].

Example kind:39000 (signing fields and unrelated tags omitted):

{
  "kind": 39000,
  "pubkey": "<relay public key>",
  "created_at": 1760025600,
  "tags": [
    ["d", "9b353519-f4fe-4757-aef4-bec6cc0ae54c"],
    ["name", "agent-config"],
    ["t", "stream"],
    ["t", "agent-config"],
    ["P", "<creator public key>"],
    ["created_at", "1759939200"]
  ]
}

Tag	Kinds	Meaning
first t	39000–39002	Channel type.
later t	39000–39002	Channel labels.
P	39000–39002	Public key that signed the kind:9007 that created the channel.
created_at	39000	Time the channel was created, in unix seconds, as a decimal string.

Channel type. Clients MUST read the channel type from the first t tag. Later t tags are labels.

Creator. The relay writes P from its own record of the kind:9007 that created the channel. No client can set it. It does not change when ownership moves to another member or when the channel is edited.

Uppercase P follows NIP-22, NIP-34 and NIP-72, where P names the author of the root object. On these kinds, lowercase p already lists members, admins and DM participants. A filter matches tag values, not their roles, so #p would mix creators with members.

Creation time. The created_at tag does not change when the channel is edited. Use it, not the event's created_at, to compare the age of channels.

Older events. A relay adds these tags only when it publishes a channel-state event. An event that a relay version without this NIP published can lack them, including one published during an upgrade. Such an event stays until the channel next changes, for example on an edit or a membership change. A client MUST treat a missing tag as unknown. A missing P does not mean that a key did not create the channel.

Channel labels

A label groups channels across channel types, for example workspace or agent-config. Labels have no meaning to the relay.

Set labels. A kind:9007 (create group) MAY carry up to 8 distinct labels as ["t", <label>] tags. On kind:9002 (edit metadata):

• t tags replace the whole label set;
• ["t", ""] tags and no other t tag clear the set;
• no t tag leaves the labels as they are.

Only an owner or admin of the channel MAY change its labels.

Rules. A label is 1–64 characters from a-z, 0-9, ., : and -. A label MUST NOT be stream, forum, dm, workflow or system. These are channel type names, so this rule stops a label from making a channel look like another type. The relay MUST reject the whole event if it has more than 8 distinct labels, an invalid label, a reserved name, or ["t", ""] together with other labels. The relay stores repeated labels once, so a repeat does not count toward the 8, and repeated ["t", ""] tags clear the set like one.

Finding channels

Use ordinary NIP-01 filters on the channel-state kinds.

To find	Filter
Channels that a key created	{"kinds": [39000], "#P": ["<creator>"]}
Channels with a label	{"kinds": [39000], "#t": ["<label>"]}
One creator's channels with a label	{"kinds": [39000], "#P": ["<creator>"], "#t": ["<label>"]}
Channels of one type	{"kinds": [39000], "#t": ["<type>"]}

A #P filter does not return a channel whose events lack P (see Older events). So it can miss channels that a key created before the relay supported this NIP.

Values in one tag filter combine with OR, as in NIP-01. So "#t": ["workspace", "notes"] finds channels with either label. To require a label and a creator, use #t and #P together.

Trust

A client that relies on these tags MUST check that the relay's key signed the event, as for all NIP-29 group-state events.

Labels give no trust. Any owner or admin can set them. Only P says who created a channel.

Relation to other NIPs

• NIP-29: the group-state events that this NIP adds tags to.
• NIP-01: the filters that find channels.
• NIP-22, NIP-34 and NIP-72: the convention for uppercase P.