diff --git a/desktop/src/features/onboarding/welcomeGuide.test.mjs b/desktop/src/features/onboarding/welcomeGuide.test.mjs
index da14cc8bd9..7f73499650 100644
--- a/desktop/src/features/onboarding/welcomeGuide.test.mjs
+++ b/desktop/src/features/onboarding/welcomeGuide.test.mjs
@@ -4,6 +4,7 @@ import test from "node:test";
 import {
   activateWelcomeTeamPersonasSequentially,
   buildWelcomeStarterCreateInput,
+  findStaleWelcomeTeamMemberPubkeys,
   LEGACY_WELCOME_GUIDE_SYSTEM_PROMPT,
   pickWelcomeGuideAgent,
   pickWelcomeGuideAgentForRelay,
@@ -18,6 +19,9 @@ import {
 const PUB_A = "a".repeat(64);
 const PUB_B = "b".repeat(64);
 const PUB_C = "c".repeat(64);
+const PUB_D = "d".repeat(64);
+const PUB_E = "e".repeat(64);
+const PUB_F = "f".repeat(64);
 const RELAY_A = "ws://localhost:3000";
 const RELAY_B = "ws://localhost:3001";
 
@@ -59,6 +63,106 @@ function makeAgent(overrides = {}) {
   };
 }
 
+function makeMember(pubkey, overrides = {}) {
+  return {
+    pubkey,
+    role: "bot",
+    isAgent: true,
+    joinedAt: "2026-07-30T00:00:00.000Z",
+    displayName: null,
+    ...overrides,
+  };
+}
+
+function makeManagedAgentEvent(pubkey, personaId, overrides = {}) {
+  return {
+    id: pubkey,
+    pubkey: PUB_F,
+    created_at: 1,
+    kind: 30177,
+    tags: [["d", pubkey]],
+    content: JSON.stringify({ persona_id: personaId }),
+    sig: "",
+    ...overrides,
+  };
+}
+
+test("stale same-owner Welcome agents are pruned while the current trio is preserved", () => {
+  const currentAgents = [
+    makeAgent({ pubkey: PUB_A, personaId: "builtin:fizz" }),
+    makeAgent({ pubkey: PUB_B, personaId: "builtin:honey" }),
+    makeAgent({ pubkey: PUB_C, personaId: "builtin:bumble" }),
+  ];
+  const members = [PUB_A, PUB_B, PUB_C, PUB_D, PUB_E].map((pubkey) =>
+    makeMember(pubkey),
+  );
+  const events = [
+    makeManagedAgentEvent(PUB_A, "builtin:fizz"),
+    makeManagedAgentEvent(PUB_B, "builtin:honey"),
+    makeManagedAgentEvent(PUB_C, "builtin:bumble"),
+    makeManagedAgentEvent(PUB_D, "builtin:fizz"),
+    makeManagedAgentEvent(PUB_E, "builtin:honey"),
+  ];
+
+  assert.deepEqual(
+    findStaleWelcomeTeamMemberPubkeys(members, events, PUB_F, currentAgents),
+    [PUB_D, PUB_E],
+  );
+});
+
+test("Welcome cleanup ignores foreign, custom, malformed, and uncertain agents", () => {
+  const currentAgents = [
+    makeAgent({ pubkey: PUB_A, personaId: "builtin:fizz" }),
+    makeAgent({ pubkey: PUB_B, personaId: "builtin:honey" }),
+    makeAgent({ pubkey: PUB_C, personaId: "builtin:bumble" }),
+  ];
+  const foreignOwner = "1".repeat(64);
+  const nonMember = "2".repeat(64);
+  const nonAgent = "3".repeat(64);
+  const invalidTag = "not-a-pubkey";
+  const members = [
+    makeMember(PUB_D),
+    makeMember(PUB_E),
+    makeMember(nonAgent, { isAgent: false }),
+  ];
+  const events = [
+    makeManagedAgentEvent(PUB_D, "builtin:fizz", {
+      pubkey: foreignOwner,
+    }),
+    makeManagedAgentEvent(PUB_E, "custom:helper"),
+    makeManagedAgentEvent(PUB_E, "builtin:honey", {
+      content: "{malformed",
+    }),
+    makeManagedAgentEvent(nonMember, "builtin:bumble"),
+    makeManagedAgentEvent(nonAgent, "builtin:fizz"),
+    makeManagedAgentEvent(invalidTag, "builtin:honey"),
+    makeManagedAgentEvent(PUB_E, "builtin:honey", { kind: 1 }),
+  ];
+
+  assert.deepEqual(
+    findStaleWelcomeTeamMemberPubkeys(members, events, PUB_F, currentAgents),
+    [],
+  );
+});
+
+test("Welcome cleanup deduplicates retained records for one stale member", () => {
+  const stale = makeManagedAgentEvent(PUB_D, "builtin:fizz");
+
+  assert.deepEqual(
+    findStaleWelcomeTeamMemberPubkeys(
+      [makeMember(PUB_D)],
+      [stale, { ...stale, id: "newer" }],
+      PUB_F,
+      [
+        makeAgent({ pubkey: PUB_A, personaId: "builtin:fizz" }),
+        makeAgent({ pubkey: PUB_B, personaId: "builtin:honey" }),
+        makeAgent({ pubkey: PUB_C, personaId: "builtin:bumble" }),
+      ],
+    ),
+    [PUB_D],
+  );
+});
+
 test("pickWelcomeGuideAgent reuses a legacy Kit guide", () => {
   const legacyKit = makeAgent({
     name: "Kit",
diff --git a/desktop/src/features/onboarding/welcomeGuide.ts b/desktop/src/features/onboarding/welcomeGuide.ts
index aa8deb7c19..6576be3b44 100644
--- a/desktop/src/features/onboarding/welcomeGuide.ts
+++ b/desktop/src/features/onboarding/welcomeGuide.ts
@@ -8,16 +8,22 @@ import {
   discoverAcpRuntimes,
   getChannelMembers,
   listManagedAgents,
+  removeChannelMember,
   updateManagedAgent,
 } from "@/shared/api/tauri";
+import { relayClient } from "@/shared/api/relayClient";
 import { getGlobalAgentConfig } from "@/shared/api/tauriGlobalAgentConfig";
+import { getIdentity } from "@/shared/api/tauriIdentity";
 import { listPersonas, setPersonaActive } from "@/shared/api/tauriPersonas";
 import type {
   AcpRuntime,
   AgentPersona,
+  ChannelMember,
   CreateManagedAgentInput,
   ManagedAgent,
+  RelayEvent,
 } from "@/shared/api/types";
+import { KIND_MANAGED_AGENT } from "@/shared/constants/kinds";
 import { normalizePubkey } from "@/shared/lib/pubkey";
 
 export const WELCOME_GUIDE_AGENT_NAME = "Fizz";
@@ -206,6 +212,101 @@ async function ensureWelcomeTeamMembership(
   }
 }
 
+const PUBKEY_PATTERN = /^[0-9a-f]{64}$/;
+
+/**
+ * Find old, same-owner built-in Welcome agents that can be safely removed from
+ * this channel after the current local trio has joined.
+ */
+export function findStaleWelcomeTeamMemberPubkeys(
+  members: readonly ChannelMember[],
+  events: readonly RelayEvent[],
+  ownerPubkey: string,
+  currentAgents: readonly ManagedAgent[],
+) {
+  const normalizedOwner = normalizePubkey(ownerPubkey);
+  const currentPubkeys = new Set(
+    currentAgents.map((agent) => normalizePubkey(agent.pubkey)),
+  );
+  const memberPubkeys = new Set(
+    members
+      .filter((member) => member.isAgent)
+      .map((member) => normalizePubkey(member.pubkey)),
+  );
+  const welcomePersonaIds = new Set<string>(
+    WELCOME_TEAM_STARTERS.map(({ personaId }) => personaId),
+  );
+  const stalePubkeys = new Set<string>();
+
+  for (const event of events) {
+    if (
+      event.kind !== KIND_MANAGED_AGENT ||
+      normalizePubkey(event.pubkey) !== normalizedOwner
+    ) {
+      continue;
+    }
+    const pubkey = normalizePubkey(
+      event.tags.find((tag) => tag[0] === "d")?.[1] ?? "",
+    );
+    if (
+      !PUBKEY_PATTERN.test(pubkey) ||
+      !memberPubkeys.has(pubkey) ||
+      currentPubkeys.has(pubkey)
+    ) {
+      continue;
+    }
+
+    try {
+      const content = JSON.parse(event.content) as { persona_id?: unknown };
+      if (
+        typeof content.persona_id === "string" &&
+        welcomePersonaIds.has(content.persona_id)
+      ) {
+        stalePubkeys.add(pubkey);
+      }
+    } catch {
+      // Malformed public metadata is not enough evidence to remove a member.
+    }
+  }
+
+  return [...stalePubkeys];
+}
+
+async function pruneStaleWelcomeTeamMemberships(
+  channelId: string,
+  currentAgents: WelcomeTeamAgents,
+) {
+  const [members, identity] = await Promise.all([
+    getChannelMembers(channelId),
+    getIdentity(),
+  ]);
+  const botPubkeys = [
+    ...new Set(
+      members
+        .filter((member) => member.isAgent)
+        .map((member) => normalizePubkey(member.pubkey))
+        .filter((pubkey) => PUBKEY_PATTERN.test(pubkey)),
+    ),
+  ];
+  if (botPubkeys.length === 0) return;
+
+  const events = await relayClient.fetchEvents({
+    kinds: [KIND_MANAGED_AGENT],
+    authors: [identity.pubkey],
+    "#d": botPubkeys,
+    limit: botPubkeys.length,
+  });
+  const stalePubkeys = findStaleWelcomeTeamMemberPubkeys(
+    members,
+    events,
+    identity.pubkey,
+    currentAgents,
+  );
+  for (const pubkey of stalePubkeys) {
+    await removeChannelMember(channelId, pubkey);
+  }
+}
+
 export async function buildWelcomeStarterCreateInput(
   starter: WelcomeTeamStarterDefinition,
   persona: AgentPersona,
@@ -337,6 +438,14 @@ async function provisionWelcomeTeam(
     }
   }
   await ensureWelcomeTeamMembership(channelId, welcomeAgents);
+  await pruneStaleWelcomeTeamMemberships(channelId, welcomeAgents).catch(
+    (error) => {
+      console.warn(
+        "[welcomeGuide] Could not prune stale Welcome Team memberships:",
+        error,
+      );
+    },
+  );
   return welcomeAgents;
 }