feat(desktop): add @everyone channel mention

desktop/src/features/messages/lib/mentionCandidates.test.mjs

@@ -2,7 +2,9 @@ import assert from "node:assert/strict";
 import test from "node:test";
 
 import {
+  buildChannelMentionCandidate,
   buildTeamMentionCandidates,
+  formatChannelMention,
   formatTeamMention,
 } from "./mentionCandidates.ts";
 
@@ -56,6 +58,50 @@ function identity(personaId, displayName, overrides = {}) {
   };
 }
 
+test("channel mention expands every other uniquely named channel member", () => {
+  const currentPubkey = "1".repeat(64);
+  const suggestion = buildChannelMentionCandidate(
+    [
+      identity(undefined, "Josh", {
+        isMember: true,
+        isAgent: false,
+        pubkey: currentPubkey,
+      }),
+      identity(undefined, "Nyx", {
+        isMember: true,
+        isAgent: true,
+        pubkey: "2".repeat(64),
+      }),
+      identity(undefined, "Solace", {
+        isMember: true,
+        isAgent: true,
+        pubkey: "3".repeat(64),
+      }),
+      identity(undefined, "Outside", {
+        isMember: false,
+        isAgent: false,
+        pubkey: "4".repeat(64),
+      }),
+    ],
+    currentPubkey,
+  );
+
+  assert.deepEqual(suggestion, {
+    kind: "channel",
+    channelMembers: [
+      { displayName: "Nyx", kind: "identity", pubkey: "2".repeat(64) },
+      { displayName: "Solace", kind: "identity", pubkey: "3".repeat(64) },
+    ],
+    displayName: "everyone",
+    isAgent: false,
+    isMember: false,
+  });
+  assert.equal(
+    formatChannelMention(suggestion.channelMembers),
+    "@Nyx @Solace ",
+  );
+});
+
 test("team mentions preserve team order and prefer concrete managed agents", () => {
   const personas = [
     persona("planner", "Planner"),

desktop/src/features/messages/lib/mentionCandidates.ts

@@ -25,19 +25,22 @@ export function appendUniqueName(current: string[], name: string): string[] {
     : [...current, name];
 }
 
-export type TeamMentionMember = {
+export type MentionGroupMember = {
   displayName: string;
   kind: "identity" | "persona";
   personaId?: string;
   pubkey?: string;
 };
 
+export type TeamMentionMember = MentionGroupMember;
+
 export type MentionCandidate = {
-  kind: "identity" | "persona" | "team";
+  kind: "identity" | "persona" | "team" | "channel";
   pubkey?: string;
   personaId?: string;
   teamId?: string;
   teamMembers?: TeamMentionMember[];
+  channelMembers?: MentionGroupMember[];
   displayName: string | null;
   avatarUrl?: string | null;
   isMember: boolean;
@@ -153,3 +156,49 @@ export function formatTeamMention(
 ) {
   return `${teamName}(${members.map((member) => `@${member.displayName}`).join(" ")}) `;
 }
+
+/** Build the safe client-side expansion for the current channel's members. */
+export function buildChannelMentionCandidate(
+  candidates: readonly MentionCandidate[],
+  currentPubkey: string | null,
+): MentionCandidate | null {
+  const channelMembers = candidates.flatMap((candidate) => {
+    if (
+      candidate.kind !== "identity" ||
+      !candidate.isMember ||
+      !candidate.pubkey ||
+      candidate.pubkey === currentPubkey
+    ) {
+      return [];
+    }
+
+    const displayName = candidate.displayName?.trim();
+    return displayName
+      ? [{ displayName, kind: "identity" as const, pubkey: candidate.pubkey }]
+      : [];
+  });
+  const names = new Set<string>();
+  if (
+    channelMembers.length === 0 ||
+    channelMembers.some((member) => {
+      const normalized = member.displayName.toLowerCase();
+      if (names.has(normalized)) return true;
+      names.add(normalized);
+      return false;
+    })
+  ) {
+    return null;
+  }
+
+  return {
+    kind: "channel",
+    channelMembers,
+    displayName: "everyone",
+    isAgent: false,
+    isMember: false,
+  };
+}
+
+export function formatChannelMention(members: readonly MentionGroupMember[]) {
+  return `${members.map((member) => `@${member.displayName}`).join(" ")} `;
+}

desktop/src/features/messages/lib/mentionRanking.ts

@@ -4,7 +4,7 @@ export type MentionCandidateForRanking = {
   displayName: string | null;
   isAgent: boolean;
   isMember: boolean;
-  kind: "identity" | "persona" | "team";
+  kind: "identity" | "persona" | "team" | "channel";
   personaId?: string | null;
   personaName?: string | null;
   pubkey?: string;

desktop/src/features/messages/lib/mentionSuggestionMapping.ts

@@ -3,14 +3,18 @@ import type { UserProfileLookup } from "@/features/profile/lib/identity";
 import { formatOwnerLabel } from "@/features/profile/lib/identity";
 import type { ChannelRole, ChannelType } from "@/shared/api/types";
 import { normalizePubkey } from "@/shared/lib/pubkey";
-import type { TeamMentionMember } from "./mentionCandidates";
+import type {
+  MentionGroupMember,
+  TeamMentionMember,
+} from "./mentionCandidates";
 
 export type MentionSuggestionCandidate = {
-  kind: "identity" | "persona" | "team";
+  kind: "identity" | "persona" | "team" | "channel";
   pubkey?: string;
   personaId?: string | null;
   teamId?: string;
   teamMembers?: TeamMentionMember[];
+  channelMembers?: MentionGroupMember[];
   avatarUrl?: string | null;
   isAgent: boolean;
   isMember: boolean;
@@ -43,6 +47,7 @@ export function mapMentionCandidateToSuggestion(opts: {
     personaId: candidate.personaId ?? undefined,
     teamId: candidate.teamId,
     teamMembers: candidate.teamMembers,
+    channelMembers: candidate.channelMembers,
     kind: candidate.kind,
     displayName: label,
     avatarUrl:
@@ -54,6 +59,7 @@ export function mapMentionCandidateToSuggestion(opts: {
     isAgent: candidate.isAgent,
     notInChannel:
       candidate.kind !== "team" &&
+      candidate.kind !== "channel" &&
       channelType !== "dm" &&
       candidate.isMember === false,
     ownerLabel,

desktop/src/features/messages/lib/useMentions.ts

@@ -50,7 +50,9 @@ import { rankMentionCandidates } from "./mentionRanking";
 import { mapMentionCandidateToSuggestion } from "./mentionSuggestionMapping";
 import {
   appendUniqueName,
+  buildChannelMentionCandidate,
   buildTeamMentionCandidates,
+  formatChannelMention,
   formatSearchUserDisplayName,
   formatSearchUserSecondaryLabel,
   formatTeamMention,
@@ -439,6 +441,10 @@ export function useMentions(
     () => getAdmittedAgentPubkeys(mentionCandidates),
     [mentionCandidates],
   );
+  const channelMentionCandidate = React.useMemo(
+    () => buildChannelMentionCandidate(mentionCandidates, currentPubkey),
+    [currentPubkey, mentionCandidates],
+  );
   const mentionCandidatesWithTeams = React.useMemo(
     () => [
       ...mentionCandidates,
@@ -447,8 +453,14 @@ export function useMentions(
         personasQuery.data ?? [],
         mentionCandidates,
       ),
+      ...(channelMentionCandidate ? [channelMentionCandidate] : []),
+    ],
+    [
+      channelMentionCandidate,
+      mentionCandidates,
+      personasQuery.data,
+      teamsQuery.data,
     ],
-    [mentionCandidates, personasQuery.data, teamsQuery.data],
   );
   const ownerPubkeys = React.useMemo(
     () => [
@@ -613,15 +625,21 @@ export function useMentions(
       }
 
       const displayName = suggestion.displayName;
-      const teamMembers =
-        suggestion.kind === "team" ? suggestion.teamMembers : null;
-      const insertText = teamMembers
-        ? formatTeamMention(displayName, teamMembers)
+      const mentionGroupMembers =
+        suggestion.kind === "team"
+          ? suggestion.teamMembers
+          : suggestion.kind === "channel"
+            ? suggestion.channelMembers
+            : null;
+      const insertText = mentionGroupMembers
+        ? suggestion.kind === "team"
+          ? formatTeamMention(displayName, mentionGroupMembers)
+          : formatChannelMention(mentionGroupMembers)
         : `@${displayName} `;
 
       const mentions = mentionMapRef.current;
       const personaMentions = personaMentionMapRef.current;
-      const selectedMentions = teamMembers ?? [suggestion];
+      const selectedMentions = mentionGroupMembers ?? [suggestion];
       for (const selected of selectedMentions) {
         if (selected.kind === "persona" && selected.personaId) {
           personaMentions.set(selected.displayName, selected.personaId);

desktop/src/features/messages/ui/MentionAutocomplete.tsx

@@ -1,6 +1,9 @@
 import * as React from "react";
 import { Bot, Users } from "lucide-react";
-import type { TeamMentionMember } from "@/features/messages/lib/mentionCandidates";
+import type {
+  MentionGroupMember,
+  TeamMentionMember,
+} from "@/features/messages/lib/mentionCandidates";
 
 import { Badge } from "@/shared/ui/badge";
 import { cn } from "@/shared/lib/cn";
@@ -18,7 +21,8 @@ export type MentionSuggestion = {
   personaId?: string;
   teamId?: string;
   teamMembers?: TeamMentionMember[];
-  kind?: "identity" | "persona" | "team";
+  channelMembers?: MentionGroupMember[];
+  kind?: "identity" | "persona" | "team" | "channel";
   displayName: string;
   avatarUrl?: string | null;
   isAgent?: boolean;
@@ -99,6 +103,7 @@ export const MentionAutocomplete = React.memo(function MentionAutocomplete({
             suggestion.pubkey ??
             (suggestion.personaId ? `persona-${suggestion.personaId}` : null) ??
             (suggestion.teamId ? `team-${suggestion.teamId}` : null) ??
+            (suggestion.kind === "channel" ? "channel-members" : null) ??
             suggestion.displayName;
           const agentLabel = "agent";
           const hasNameCollision =
@@ -125,7 +130,7 @@ export const MentionAutocomplete = React.memo(function MentionAutocomplete({
               tabIndex={-1}
               type="button"
             >
-              {suggestion.kind === "team" ? (
+              {suggestion.kind === "team" || suggestion.kind === "channel" ? (
                 <span className="flex h-6 w-6 shrink-0 items-center justify-center rounded-full bg-primary/10 text-primary">
                   <Users aria-hidden="true" className="h-4 w-4" />
                 </span>
@@ -142,9 +147,12 @@ export const MentionAutocomplete = React.memo(function MentionAutocomplete({
                   className="min-w-0 break-words font-medium leading-snug"
                   title={suggestion.displayName}
                 >
-                  {suggestion.displayName}
+                  {suggestion.kind === "channel"
+                    ? `@${suggestion.displayName}`
+                    : suggestion.displayName}
                 </span>
                 {suggestion.kind === "team" ||
+                suggestion.kind === "channel" ||
                 suggestion.isAgent ||
                 suggestion.role ||
                 suggestion.ownerLabel ||
@@ -162,6 +170,12 @@ export const MentionAutocomplete = React.memo(function MentionAutocomplete({
                         <Users aria-hidden="true" className="h-3.5 w-3.5" />
                         team · {suggestion.teamMembers?.length ?? 0} agents
                       </span>
+                    ) : suggestion.kind === "channel" ? (
+                      <span className="inline-flex shrink-0 items-center gap-1">
+                        <Users aria-hidden="true" className="h-3.5 w-3.5" />
+                        everyone · {suggestion.channelMembers?.length ?? 0}{" "}
+                        members
+                      </span>
                     ) : suggestion.isAgent ? (
                       <span className="inline-flex shrink-0 items-center gap-1">
                         <Bot

desktop/tests/e2e/mentions.spec.ts

@@ -344,6 +344,25 @@ test("relay-only shared agents emit an outbound mention tag when selected", asyn
     .toContain(TEST_IDENTITIES.alice.pubkey);
 });
 
+test("channel mention selects every other current member", async ({ page }) => {
+  await page.goto("/");
+  await page.getByTestId("channel-general").click();
+
+  const composer = page.getByTestId("message-composer");
+  const input = composer.getByTestId("message-input");
+  await input.fill("Notify @everyone");
+
+  const channelMention = composer.getByTestId(
+    "mention-suggestion-channel-members",
+  );
+  await expect(channelMention).toContainText("@everyone");
+  await expect(channelMention).toContainText("everyone · 2 members");
+  await channelMention.click();
+
+  const content = "Notify @alice @bob ";
+  await expect(input).toHaveText(content);
+});
+
 test("thread autocomplete keeps multiple long names readable in a narrow panel", async ({
   page,
 }) => {