Files
buzz/migrations/0061_channel_labels.sql
Logan Johnson 2f79374f48 feat(relay): channel labels (#8175)
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## Summary
A plugin or agent often needs to tag its own channels and then find them
again, for example "my attention-config channel" or "all channels of
this workspace". Today a channel has no labels: the relay ignores any
`t` tags in create or edit requests. This PR adds channel labels.

- A create request can carry up to 8 labels as `["t", "<label>"]` tags.
- An edit request with `t` tags replaces the label set. `["t", ""]`
alone clears it, the same convention as `["ttl", ""]`. Only owners and
admins can change labels, as for the name.
- The relay publishes each label as a `t` tag on the channel's state
events, after the channel type tag.

Part 2 of 3, stacked on part 1.

### Related issue
None found.

### Details
- **Rules.** A label uses 1–64 characters from `a-z`, `0-9`, `.`, `:`
and `-`. The relay refuses a label equal to a channel type name
(`stream`, `forum`, `dm`, `workflow`, `system`), so a label cannot make
a channel look like another type.
- **No trust from labels.** Any admin can set a label. Only the
relay-written creator tag (part 1) says who made a channel.
- **Storage.** New migration `0061_channel_labels.sql` adds
`channels.labels TEXT[] NOT NULL DEFAULT '{}'`. Channels without labels
look and behave as before.
- **Readers.** The CLI and `buzz-acp` read the channel type from the
first `t` tag. Before this PR they used the last one, which would now be
a label.
- **Spec.** NIP-CL gets a "Channel labels" section with these rules.

### Testing
- Relay tests: labels at creation appear after the type tag, edit
replaces and clears them, invalid labels are refused, and members who
are not admins cannot change them.
- Unit tests for the label rules: allowed characters, length, reserved
type names, the 8-label cap and the clear marker.
- `buzz-acp` test: the channel type comes from the first `t` tag, not a
label.

### Stack
These are two stacks. Merge them in this order. Client support
(creating, labeling and finding these channels) will be in
block/buzz-app, not the buzz SDK and CLI.

**Stack 1: channel labels and creator lookup (#8174–#8176)**

1. #8174 channel type and creator tags, and the channel creation time
2. #8175 channel labels ← this PR
3. #8176 database-side label and creator match, and the rule for
choosing one channel

**Stack 2: system channels (#8180–#8182)**, stacked on stack 1 because
it uses labels and the creator tag

4. #8180 the system channel type
5. #8181 leave system channels out of reads that do not name them
6. #8182 channel-state filters opt in to system channels

---------

Signed-off-by: Logan Johnson <loganj@squareup.com>
Co-authored-by: Larry <627498bd4bd1f281a16431e3c6cce3b5c25b6692798c78672298aefbf2f8f8b5@buzz.block.builderlab.xyz>
2026-10-14 17:25:46 -04:00

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SQL

-- Channel labels: creator- or admin-chosen tags that group channels across
-- channel types. The relay publishes each label as a ["t", <label>] tag on
-- the channel's group-state events (kinds 39000-39002), after the channel
-- type tag. kind:9007 sets them and kind:9002 replaces them; the relay
-- validates their shape (1-64 of a-z 0-9 . : -, not a channel type name).
--
-- Additive: existing channels get an empty set and look as before. The
-- CHECK bounds the set even if a writer skips the relay's validation.
-- No index yet: label lookups match the GIN-indexed tags of the relay-signed
-- group-state events, not this column.
ALTER TABLE channels
ADD COLUMN labels TEXT[] NOT NULL DEFAULT '{}'
CONSTRAINT channels_labels_bounded CHECK (cardinality(labels) <= 8);