feat(soup): channel_thread participants filter

[synoet]

Adds a participants filter to the channel_thread entity across all three soup surfaces (regular typed filters, AST endpoint, and GraphQL).

A user is a participant of a thread when they are still an active member of the channel AND any of:

• they sent the root message or any reply in the thread,
• they were @-mentioned anywhere in the thread.

Group mentions (@here) are covered by the second arm: the client expands them into per-user mention rows for every channel member at send time. That expansion is a send-time snapshot from the web client only, so members who join later and messages from non-expanding producers (bots, webhooks) are missed — a TODO on the filter documents the follow-up of persisting group mentions as entity_type = 'group' rows in comms_entity_mentions (parsed server-side from the <m-group-mention> content tag) and treating every active member as a participant of threads containing one.

How

• item_filters: new participant_ids field on ChannelThreadFilters and a Participant variant on ChannelThreadLiteral. The AST endpoint (cthf) and MCP toolset pick the new literal up automatically.
• channels: push_channel_thread_filter_expr compiles the literal to an EXISTS subquery over the thread's non-deleted messages (senders) and comms_entity_mentions user mentions, gated on active channel membership (left_at IS NULL), mirroring the semantics of get_channel_participants_for_thread_id.
• graphql_soup: participant oneof field on GraphqlChannelThreadLiteral; schema.graphql regenerated.
• service-clients: openapi.json + generated types updated for the new field (storage and search).

[macro-application]

feat(soup): channel_thread participant filter

[coderabbitai]

📝 Walkthrough

Walkthrough

This change adds participant-based filtering for channel threads. A new participant_ids field is added to ChannelThreadFilters in the search and storage OpenAPI schemas, the item_filters crate, and the GraphQL schema/input (participant/Participant). The AST expansion adds a ChannelThreadLiteral::Participant variant that parses participant user IDs into filter expressions. The Postgres repository implements a new SQL predicate matching participants via channel membership, message senders, group mentions, or persisted entity mentions. New fixtures and tests validate reply/mention, group mention, root sender, and departed-user exclusion scenarios.

Changes

Area	Change
OpenAPI schemas	Added participant_ids array field to ChannelThreadFilters in search and storage specs
GraphQL	Added participant field to GraphqlChannelThreadLiteral input; added Participant variant and conversion logic
item_filters	Added participant_ids field and updated is_empty; added Participant AST literal and expansion logic
Postgres repository	Added SQL generation for participant filtering via EXISTS predicate covering senders, group mentions, and entity mentions
Fixtures/tests	Added channel ch4 fixture data and four new tests validating participant filter behavior

Sequence Diagram(s)

sequenceDiagram
  participant Client
  participant GraphqlSoup
  participant ItemFiltersAST
  participant PgChannelsRepo
  participant Postgres

  Client->>GraphqlSoup: GraphqlChannelThreadLiteral(Participant)
  GraphqlSoup->>ItemFiltersAST: parse_macro_user_id -> ChannelThreadLiteral::Participant
  ItemFiltersAST->>PgChannelsRepo: push_channel_thread_filter_expr(Participant)
  PgChannelsRepo->>PgChannelsRepo: push_channel_thread_participant_filter_expr
  PgChannelsRepo->>Postgres: EXISTS query (membership, sender, mention match)
  Postgres-->>PgChannelsRepo: matching thread rows
  PgChannelsRepo-->>Client: filtered threads

Loading

Related Issues: None found in provided context.

Related PRs: None found in provided context.

Suggested labels: rust, graphql, database, feature

Suggested reviewers: None specified.

Poem:
A rabbit sniffs through threads and mentions,
Tracing who joined with keen intentions,
Root, reply, or @-tag in sight,
Group mentions matched just right,
Filters bloom with new dimensions. 🐇✨

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title follows conventional commits format and clearly summarizes the participant filter change.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description check	✅ Passed	The description matches the changeset by describing the new participants filter across filters, AST, GraphQL, service clients, and channel search logic.

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}

[github-actions]

Preview: https://synoet-macro-2143-featsoup-cha-1b8cuz.preview.macro.com/app (40c89d4)