Hide non-invocable member agents from @-mention autocomplete

[atishpatel]

Problem

Agents you can't invoke — e.g. Fizz, owned by another team — still show up in the composer's @-mention autocomplete when they've been added to a channel as members.

The autocomplete already has an invocability filter (useMentions.ts), but it only applied to agents that aren't channel members:

if (candidate.isAgent && !candidate.isMember && !mentionableAgentPubkeys.has(pubkey)) return;

Fizz is added to the channel as a member by its owning team, so !candidate.isMember is false, the check is skipped, and Fizz always appears — even though the backend (author_allowed in buzz-acp) would reject a mention of it.

Fix

Extract the show/hide decision into a pure, tested helper shouldHideAgentFromMentions(...) and apply it to all agent candidates, member or not. The "can I invoke this agent" set (getMentionableAgentPubkeys) is unchanged and continues to mirror the backend gate.

Semantics (member agents are the new case):

candidate	result
not an agent	show
invocable (in mentionableAgentPubkeys)	show
non-member & not invocable	hide (unchanged prior behavior)
member & not invocable & in relay directory (kind:10100)	hide (this is Fizz)
member & not invocable & not in directory (unknown / still loading)	show

The last row is deliberate: we only hide a member agent when we have an explicit not-invocable signal (a directory entry that excludes the current user). If the agent's directory profile is missing or still loading, invocability is unknown and we keep showing it — we never hide an agent we can't confirm is non-invocable. useMentions builds a directoryAgentPubkeys set from relayAgentsQuery.data to supply that signal.

Tests

Adds unit tests in agentAutocompleteEligibility.test.mjs covering every branch, including both member cases (Fizz hidden; unknown-invocability shown) and npub/hex pubkey normalization.

• node --test → 17/17 pass
• biome check (3 changed files) → clean
• tsc --noEmit → 0 errors

[wpfleger96]

Reviewed and re-verified at source (ran the tests + typecheck myself). Clean, minimal, well-scoped fix.

The extraction of shouldHideAgentFromMentions into a pure helper is the right move, and the branch ordering reads clearly: non-agent → show, invocable → show, non-member non-invocable → hide (preserves prior behavior), member → hide only on an explicit not-invocable directory signal. The "only hide when we can confirm non-invocable" stance on the last row is the correct conservative default — a member agent whose directory profile is still loading stays visible rather than flickering out.

Provenance is consistent: directoryAgentPubkeys and mentionableAgentPubkeys are both derived from relayAgentsQuery.data, so "in the directory but not mentionable" is a real explicit-exclusion signal, not an artifact of two unsynced sources. I also checked the other !candidate.isMember use (extractMentionPubkeys, useMentions.ts:830) — it iterates mentionCandidates, which is already filtered by this helper upstream, so a hidden member agent can't be re-extracted from text there. No missed filter path.

Verified locally: node --test on the eligibility suite → 17/17 pass; tsc --noEmit → clean. One optional note inline; nothing blocking.