fix(desktop): switch to existing community on buzz://connect deep links

desktop/src/app/App.tsx

@@ -41,6 +41,7 @@ import {
   onAddCommunityPrefillAvailable,
   requestAddCommunityPrefill,
 } from "@/features/communities/addCommunityPrefill";
+import { findCommunityByRelayUrl } from "@/features/communities/communityStorage";
 import { WelcomeSetup } from "@/features/communities/ui/WelcomeSetup";
 import { CommunityApplyErrorScreen } from "@/features/communities/ui/CommunityApplyErrorScreen";
 import { CommunityChangeOverlay } from "@/features/communities/ui/CommunityChangeOverlay";
@@ -333,9 +334,19 @@ function CommunityApp({
       return;
     }
     const previousCommunityId = activeCommunity?.id;
-    const relayAlreadyExists = communities.some(
-      (community) => community.relayUrl === transaction.relayUrl,
+    const existingCommunity = findCommunityByRelayUrl(
+      communities,
+      transaction.relayUrl,
     );
+    if (existingCommunity) {
+      switchCommunity(existingCommunity.id);
+      reconnectCommunity();
+      if (currentPubkey) {
+        markCommunityOnboardingComplete(currentPubkey, transaction.relayUrl);
+      }
+      communityOnboarding.clear();
+      return;
+    }
     const id = addCommunity({
       id: crypto.randomUUID(),
       name: transaction.communityName,
@@ -348,7 +359,7 @@ function CommunityApp({
     communityOnboarding.update({
       communityId: id,
       previousCommunityId,
-      addedCommunity: !relayAlreadyExists,
+      addedCommunity: true,
       error: undefined,
     });
     switchCommunity(id);
@@ -540,7 +551,8 @@ function CommunityApp({
 }
 
 function MachineBootstrap({ sharedIdentity }: { sharedIdentity: boolean }) {
-  const { activeCommunity } = useCommunities();
+  const { activeCommunity, communities, switchCommunity, reconnectCommunity } =
+    useCommunities();
   const communityOnboarding = useCommunityOnboarding();
   const machine = useMachineOnboardingState({
     activeCommunityPubkey: activeCommunity
@@ -576,6 +588,24 @@ function MachineBootstrap({ sharedIdentity }: { sharedIdentity: boolean }) {
     [activeCommunity, communityOnboarding.start],
   );
 
+  const switchToCommunityRelay = useCallback(
+    (relayUrl: string) => {
+      const existing = findCommunityByRelayUrl(communities, relayUrl);
+      if (!existing) return false;
+
+      communityOnboarding.clear();
+      switchCommunity(existing.id);
+      reconnectCommunity();
+      return true;
+    },
+    [
+      communities,
+      communityOnboarding.clear,
+      reconnectCommunity,
+      switchCommunity,
+    ],
+  );
+
   // Deep links are captured here — above the machine-onboarding gate — not in
   // CommunityApp. The Rust side queues them; draining into the persisted
   // community-onboarding transaction immediately means an invite opened on a
@@ -584,13 +614,14 @@ function MachineBootstrap({ sharedIdentity }: { sharedIdentity: boolean }) {
   useEffect(() => {
     const unlisten = listenForDeepLinks({
       startCommunityOnboarding: communityOnboarding.start,
+      switchToCommunityRelay,
       openAddCommunity,
       onAddCommunityAvailable: onAddCommunityPrefillAvailable,
     });
     return () => {
       void unlisten.then((fn) => fn());
     };
-  }, [communityOnboarding.start, openAddCommunity]);
+  }, [communityOnboarding.start, openAddCommunity, switchToCommunityRelay]);
 
   if (machine.stage === "reset-failed") return <ResetFailedScreen />;
   if (machine.stage === "keyring-locked") return <KeyringLockedScreen />;

desktop/src/features/communities/communityStorage.test.mjs

@@ -2,7 +2,9 @@ import assert from "node:assert/strict";
 import test from "node:test";
 
 import {
+  canonicalCommunityRelayUrl,
   clearCommunityStorage,
+  findCommunityByRelayUrl,
   initFirstCommunity,
   migrateLegacyCommunityStorage,
   shouldAutoConnectDefaultRelay,
@@ -102,3 +104,66 @@ test("clearCommunityStorage removes new and legacy state", () => {
 
   assert.equal(storage.length, 0);
 });
+
+test("canonicalCommunityRelayUrl normalizes case and trailing slashes", () => {
+  assert.equal(
+    canonicalCommunityRelayUrl("WSS://Buzz.Block.Builderlab.xyz/"),
+    "wss://buzz.block.builderlab.xyz",
+  );
+  assert.equal(
+    canonicalCommunityRelayUrl("wss://buzz.block.builderlab.xyz"),
+    "wss://buzz.block.builderlab.xyz",
+  );
+});
+
+test("canonicalCommunityRelayUrl normalizes loopback host spellings", () => {
+  assert.equal(
+    canonicalCommunityRelayUrl("ws://localhost:3000"),
+    "ws://127.0.0.1:3000",
+  );
+  assert.equal(
+    canonicalCommunityRelayUrl("ws://127.0.0.1:3000"),
+    "ws://127.0.0.1:3000",
+  );
+});
+
+test("findCommunityByRelayUrl matches stored communities canonically", () => {
+  const communities = [
+    {
+      id: "builderlab",
+      name: "Builderlab",
+      relayUrl: "wss://Buzz.Block.Builderlab.xyz/",
+      addedAt: "2026-07-23T00:00:00.000Z",
+    },
+    {
+      id: "other",
+      name: "Other",
+      relayUrl: "wss://other.example",
+      addedAt: "2026-07-23T00:00:00.000Z",
+    },
+  ];
+
+  assert.equal(
+    findCommunityByRelayUrl(communities, "wss://buzz.block.builderlab.xyz")?.id,
+    "builderlab",
+  );
+  assert.equal(
+    findCommunityByRelayUrl(communities, "wss://missing.example"),
+    undefined,
+  );
+});
+
+test("findCommunityByRelayUrl matches localhost against 127.0.0.1", () => {
+  const communities = [
+    {
+      id: "local",
+      name: "Local Dev",
+      relayUrl: "ws://127.0.0.1:3000",
+      addedAt: "2026-07-23T00:00:00.000Z",
+    },
+  ];
+  assert.equal(
+    findCommunityByRelayUrl(communities, "ws://localhost:3000")?.id,
+    "local",
+  );
+});

desktop/src/features/communities/communityStorage.ts

@@ -127,6 +127,46 @@ export function shouldAutoConnectDefaultRelay(relayUrl: string): boolean {
   }
 }
 
+/**
+ * Canonical ws(s) relay URL for community matching and deduplication.
+ * Deep links, stored communities, and relay probes may spell the same relay
+ * differently (case, trailing slash); compare via this form.
+ */
+export function canonicalCommunityRelayUrl(rawRelayUrl: string): string {
+  const trimmed = rawRelayUrl.trim();
+  const withScheme = /^(ws|wss):\/\//i.test(trimmed)
+    ? trimmed
+    : normalizeRelayUrl(trimmed);
+  const parsed = new URL(withScheme);
+  const protocol = parsed.protocol.toLowerCase();
+  let host = parsed.hostname.toLowerCase();
+  if (host === "localhost" || host === "[::1]" || host.startsWith("127.")) {
+    host = "127.0.0.1";
+  }
+  const defaultPort = protocol === "ws:" ? "80" : "443";
+  const port =
+    parsed.port && parsed.port !== defaultPort ? `:${parsed.port}` : "";
+  const path =
+    parsed.pathname.replace(/\/+$/, "") === "" ||
+    parsed.pathname.replace(/\/+$/, "") === "/"
+      ? ""
+      : parsed.pathname.replace(/\/+$/, "");
+  return `${protocol}//${host}${port}${path}${parsed.search}`.replace(
+    /\/+$/,
+    "",
+  );
+}
+
+export function findCommunityByRelayUrl(
+  communities: readonly Community[],
+  relayUrl: string,
+): Community | undefined {
+  const canonical = canonicalCommunityRelayUrl(relayUrl);
+  return communities.find(
+    (community) => canonicalCommunityRelayUrl(community.relayUrl) === canonical,
+  );
+}
+
 export function deriveCommunityName(relayUrl: string): string {
   try {
     const url = new URL(

desktop/src/features/communities/useCommunities.tsx

@@ -11,6 +11,7 @@ import type { ReactNode } from "react";
 import type { Community } from "./types";
 import {
   clearCommunityStorage,
+  canonicalCommunityRelayUrl,
   loadActiveCommunityId,
   loadCommunities,
   saveActiveCommunityId,
@@ -43,12 +44,18 @@ export function resolveCommunityUpdateResult(
   const current = communities.find((w) => w.id === id);
   if (!current) return { kind: "not-found" };
 
-  if (
-    updates.relayUrl !== undefined &&
-    updates.relayUrl !== current.relayUrl &&
-    communities.some((w) => w.id !== id && w.relayUrl === updates.relayUrl)
-  ) {
-    return { kind: "duplicate-relay" };
+  if (updates.relayUrl !== undefined && updates.relayUrl !== current.relayUrl) {
+    const nextRelayUrl = updates.relayUrl;
+    if (
+      communities.some(
+        (w) =>
+          w.id !== id &&
+          canonicalCommunityRelayUrl(w.relayUrl) ===
+            canonicalCommunityRelayUrl(nextRelayUrl),
+      )
+    ) {
+      return { kind: "duplicate-relay" };
+    }
   }
 
   const hasChange =
@@ -165,12 +172,15 @@ function useCommunitiesInternal(): UseCommunitiesReturn {
   );
 
   const addCommunity = useCallback((community: Community): string => {
+    const canonical = canonicalCommunityRelayUrl(community.relayUrl);
     const existing = communitiesRef.current.find(
-      (w) => w.relayUrl === community.relayUrl,
+      (w) => canonicalCommunityRelayUrl(w.relayUrl) === canonical,
     );
     const resolvedId = existing?.id ?? community.id;
     setCommunitiesState((prev) => {
-      const dup = prev.find((w) => w.relayUrl === community.relayUrl);
+      const dup = prev.find(
+        (w) => canonicalCommunityRelayUrl(w.relayUrl) === canonical,
+      );
       let next: Community[];
       if (dup) {
         next = prev.map((w) =>

desktop/src/features/onboarding/communityOnboarding.tsx

@@ -1,6 +1,6 @@
 import {
+  canonicalCommunityRelayUrl,
   deriveCommunityName,
-  normalizeRelayUrl,
 } from "@/features/communities/communityStorage";
 import { setLocalStorageItemWithRecovery } from "@/shared/lib/localStorageQuota";
 import type { Profile } from "@/shared/api/types";
@@ -82,18 +82,6 @@ export type StartCommunityOnboardingInput = {
   policyReceipt?: string;
 };
 
-function canonicalRelayUrl(rawRelayUrl: string) {
-  const trimmed = rawRelayUrl.trim();
-  const withScheme = /^(ws|wss):\/\//i.test(trimmed)
-    ? trimmed
-    : normalizeRelayUrl(trimmed);
-  const parsed = new URL(withScheme);
-  parsed.protocol = parsed.protocol.toLowerCase();
-  parsed.hostname = parsed.hostname.toLowerCase();
-  parsed.pathname = parsed.pathname.replace(/\/+$/, "") || "/";
-  return parsed.toString().replace(/\/$/, "");
-}
-
 function isTransaction(
   value: unknown,
 ): value is CommunityOnboardingTransaction {
@@ -151,9 +139,12 @@ export function startCommunityOnboarding(
   storage: Storage = localStorage,
   now = new Date(),
 ): CommunityOnboardingTransaction {
-  const relayUrl = canonicalRelayUrl(input.relayUrl);
+  const relayUrl = canonicalCommunityRelayUrl(input.relayUrl);
   const existing = loadCommunityOnboardingTransaction(storage);
   if (existing?.relayUrl === relayUrl) {
+    const reopenConnect =
+      input.source === "deep-link-connect" &&
+      existing.source === "deep-link-connect";
     const updated = {
       ...existing,
       firstCommunityPage:
@@ -163,6 +154,12 @@ export function startCommunityOnboarding(
       token: input.token?.trim() || existing.token,
       reposDir: input.reposDir ?? existing.reposDir,
       policyReceipt: input.policyReceipt ?? existing.policyReceipt,
+      stage: reopenConnect ? "connecting" : existing.stage,
+      communityId: reopenConnect ? undefined : existing.communityId,
+      previousCommunityId: reopenConnect
+        ? undefined
+        : existing.previousCommunityId,
+      addedCommunity: reopenConnect ? undefined : existing.addedCommunity,
       updatedAt: now.toISOString(),
       error: undefined,
       // A freshly opened link deserves fresh feedback — re-present the gate
@@ -339,7 +336,7 @@ export function CommunityOnboardingProvider({
     (input: StartCommunityOnboardingInput) => {
       if (
         transaction &&
-        canonicalRelayUrl(input.relayUrl) !== transaction.relayUrl
+        canonicalCommunityRelayUrl(input.relayUrl) !== transaction.relayUrl
       ) {
         return false;
       }

desktop/src/shared/deep-link.ts

@@ -9,6 +9,7 @@ export type AddCommunityDeepLinkPayload = {
 
 export interface DeepLinkDeps {
   startCommunityOnboarding: (input: StartCommunityOnboardingInput) => boolean;
+  switchToCommunityRelay: (relayUrl: string) => boolean;
   openAddCommunity: (
     payload: AddCommunityDeepLinkPayload & { requestId: string },
   ) => boolean;
@@ -62,6 +63,15 @@ function acceptPendingCommunityDeepLink(
   pending: PendingCommunityDeepLink,
   deps: DeepLinkDeps,
 ) {
+  if (
+    pending.kind === "connect" &&
+    deps.switchToCommunityRelay(pending.relayUrl)
+  ) {
+    return invoke<boolean>("acknowledge_pending_community_deep_link", {
+      id: pending.id,
+    });
+  }
+
   const accepted =
     pending.kind === "add-community"
       ? deps.openAddCommunity({
@@ -98,8 +108,9 @@ async function drainPendingCommunityDeepLinks(deps: DeepLinkDeps) {
  * Register listeners for deep-link events emitted by the Rust backend.
  *
  * When a `buzz://connect?relay=<url>` link is opened, the handler
- * adds a community for the relay (deduplicating by URL) and switches
- * to it. Returns an unlisten function to tear down all listeners.
+ * switches to an existing community for that relay (matching canonically)
+ * or starts community onboarding to add and connect a new one. Returns an
+ * unlisten function to tear down all listeners.
  *
  * When a `buzz://join?relay=<url>&code=<invite>` link is opened (relay
  * invite landing page), the handler first claims the invite against the