diff --git a/desktop/src/features/agents/lib/useAgentsDataRefresh.ts b/desktop/src/features/agents/lib/useAgentsDataRefresh.ts
index 174fb9c92c..b65a816776 100644
--- a/desktop/src/features/agents/lib/useAgentsDataRefresh.ts
+++ b/desktop/src/features/agents/lib/useAgentsDataRefresh.ts
@@ -1,3 +1,4 @@
+import { isTauri } from "@tauri-apps/api/core";
 import { listen } from "@tauri-apps/api/event";
 import { useQueryClient } from "@tanstack/react-query";
 import { useEffect } from "react";
@@ -26,6 +27,11 @@ export function useAgentsDataRefresh(): void {
   const queryClient = useQueryClient();
 
   useEffect(() => {
+    // Both events come from the local Rust agents backend — no on-disk agents
+    // data exists in a browser (web) runtime, and `listen()` throws without
+    // Tauri internals.
+    if (!isTauri()) return;
+
     let timer: ReturnType<typeof setTimeout> | undefined;
 
     const unlistenRuntime = listen("managed-agent-runtime-status", () => {
diff --git a/desktop/src/features/agents/usePreventSleep.ts b/desktop/src/features/agents/usePreventSleep.ts
index 4c2d48b97d..5dc4db5c25 100644
--- a/desktop/src/features/agents/usePreventSleep.ts
+++ b/desktop/src/features/agents/usePreventSleep.ts
@@ -7,6 +7,7 @@ import {
 import { createPreventSleepActivityTracker } from "@/features/agents/preventSleepActivity";
 import { setPreventSleepActive } from "@/shared/api/tauri";
 import { normalizePubkey } from "@/shared/lib/pubkey";
+import { isTauri } from "@tauri-apps/api/core";
 import { listen } from "@tauri-apps/api/event";
 
 // Intentionally not scoped per-pubkey — multi-user desktop is rare and the
@@ -85,6 +86,10 @@ function usePreventSleepInternal() {
     void setPreventSleepActive(active);
   }, [active]);
   React.useEffect(() => {
+    // Sleep prevention is a native OS concept — no such event exists in a
+    // browser (web) runtime, and `listen()` throws without Tauri internals.
+    if (!isTauri()) return;
+
     const unlisten = listen("prevent-sleep-expired", () => {
       setExpired(true);
     });
diff --git a/desktop/src/features/communities/legacyCommunityStorage.ts b/desktop/src/features/communities/legacyCommunityStorage.ts
index d140fa4c62..2bc51c26ca 100644
--- a/desktop/src/features/communities/legacyCommunityStorage.ts
+++ b/desktop/src/features/communities/legacyCommunityStorage.ts
@@ -1,3 +1,5 @@
+import { isTauri } from "@tauri-apps/api/core";
+
 import { invokeTauri } from "@/shared/api/tauri";
 import { migrateLegacyCommunityStorage } from "./communityStorage";
 
@@ -115,6 +117,12 @@ export async function migrateLegacyCommunityStorageBeforeRender(): Promise<void>
     return;
   }
 
+  // The legacy Sprout WebKit SQLite database only exists in the native shell
+  // — there is nothing to migrate from in a browser (web) runtime.
+  if (!isTauri()) {
+    return;
+  }
+
   migrateLegacyCommunityStorage(window.localStorage);
   const currentCommunitiesRaw =
     window.localStorage.getItem(BUZZ_COMMUNITIES_KEY);
diff --git a/desktop/src/features/communities/useNestNotifications.ts b/desktop/src/features/communities/useNestNotifications.ts
index d93bb89ad2..41ebd75ee6 100644
--- a/desktop/src/features/communities/useNestNotifications.ts
+++ b/desktop/src/features/communities/useNestNotifications.ts
@@ -1,3 +1,4 @@
+import { isTauri } from "@tauri-apps/api/core";
 import { listen } from "@tauri-apps/api/event";
 import { useEffect } from "react";
 import { toast } from "sonner";
@@ -22,6 +23,10 @@ const MIGRATION_TOAST_KEY = "buzz-legacy-nest-migrated-notified";
  */
 export function useNestNotifications(): void {
   useEffect(() => {
+    // Both events come from the Rust nest backend — no local nest exists in a
+    // browser (web) runtime, and `listen()` throws without Tauri internals.
+    if (!isTauri()) return;
+
     const unlistenReposError = listen<string>("repos-dir-error", (event) => {
       toast.error("Repos directory not applied", {
         description: event.payload,
diff --git a/desktop/src/features/huddle/HuddleContext.tsx b/desktop/src/features/huddle/HuddleContext.tsx
index 804eb4bc0e..7874b6f996 100644
--- a/desktop/src/features/huddle/HuddleContext.tsx
+++ b/desktop/src/features/huddle/HuddleContext.tsx
@@ -1,4 +1,4 @@
-import { invoke } from "@tauri-apps/api/core";
+import { invoke, isTauri } from "@tauri-apps/api/core";
 import { listen } from "@tauri-apps/api/event";
 import * as React from "react";
 
@@ -616,6 +616,10 @@ export function HuddleProvider({ children }: { children: React.ReactNode }) {
   // in-flight guard collapses duplicate disconnect events from failed dials.
   const audioReconnectInFlightRef = React.useRef(false);
   React.useEffect(() => {
+    // Huddle audio is a native Tauri pipeline — no such event exists in a
+    // browser (web) runtime, and `listen()` throws without Tauri internals.
+    if (!isTauri()) return;
+
     let cancelled = false;
     let unlisten: (() => void) | null = null;
     listen("huddle-audio-disconnected", () => {
diff --git a/desktop/src/features/huddle/components/HuddleBar.tsx b/desktop/src/features/huddle/components/HuddleBar.tsx
index 35d660e475..eab1a95e76 100644
--- a/desktop/src/features/huddle/components/HuddleBar.tsx
+++ b/desktop/src/features/huddle/components/HuddleBar.tsx
@@ -1,4 +1,4 @@
-import { invoke } from "@tauri-apps/api/core";
+import { invoke, isTauri } from "@tauri-apps/api/core";
 import { listen } from "@tauri-apps/api/event";
 import {
   Bot,
@@ -216,6 +216,11 @@ export function HuddleBar({
   }, []);
   // Huddle state: event-driven + slow fallback poll.
   React.useEffect(() => {
+    // The huddle backend (state + audio pipeline) is native Tauri-only — none
+    // of this works in a browser (web) runtime, and `listen()` throws without
+    // Tauri internals.
+    if (!isTauri()) return;
+
     let cancelled = false;
     let unlisten: (() => void) | null = null;
 
diff --git a/desktop/src/features/huddle/components/HuddleIndicator.tsx b/desktop/src/features/huddle/components/HuddleIndicator.tsx
index 19b504cf28..bf11d78417 100644
--- a/desktop/src/features/huddle/components/HuddleIndicator.tsx
+++ b/desktop/src/features/huddle/components/HuddleIndicator.tsx
@@ -1,3 +1,4 @@
+import { isTauri } from "@tauri-apps/api/core";
 import { listen } from "@tauri-apps/api/event";
 import { Headphones } from "lucide-react";
 import * as React from "react";
@@ -190,6 +191,11 @@ export function HuddleIndicator({
   // waiting for the relay's 48103 event (which may arrive late or not at all
   // if the relay connection tears down first).
   React.useEffect(() => {
+    // Huddle state is emitted by the native Tauri audio pipeline — no such
+    // event exists in a browser (web) runtime, and `listen()` throws without
+    // Tauri internals.
+    if (!isTauri()) return;
+
     let unlisten: (() => void) | null = null;
     let cancelled = false;
 
diff --git a/desktop/src/features/settings/ui/MobilePairingCard.tsx b/desktop/src/features/settings/ui/MobilePairingCard.tsx
index e15f54316b..2719f24397 100644
--- a/desktop/src/features/settings/ui/MobilePairingCard.tsx
+++ b/desktop/src/features/settings/ui/MobilePairingCard.tsx
@@ -8,6 +8,7 @@ import {
   TriangleAlert,
   X,
 } from "lucide-react";
+import { isTauri } from "@tauri-apps/api/core";
 import { listen } from "@tauri-apps/api/event";
 import { toast } from "sonner";
 
@@ -220,6 +221,13 @@ export function MobilePairingCard({
       return;
     }
 
+    // Mobile pairing is a native Tauri feature (QR/SAS handshake with a
+    // phone) — none of these events exist in a browser (web) runtime, and
+    // `listen()` throws without Tauri internals.
+    if (!isTauri()) {
+      return;
+    }
+
     let cancelled = false;
     const unlisteners: (() => void)[] = [];
 
diff --git a/desktop/src/shared/api/tauri.ts b/desktop/src/shared/api/tauri.ts
index e8a8b885cf..8ae7cec8e5 100644
--- a/desktop/src/shared/api/tauri.ts
+++ b/desktop/src/shared/api/tauri.ts
@@ -1,4 +1,4 @@
-import { invoke as tauriInvoke } from "@tauri-apps/api/core";
+import { invoke as tauriInvoke, isTauri } from "@tauri-apps/api/core";
 import {
   activateRateLimit,
   parseRateLimitHint,
@@ -366,15 +366,26 @@ export async function getPresence(pubkeys: string[]): Promise<PresenceLookup> {
   );
 }
 
+// Called unconditionally on every boot by useCommunityInit's "no active
+// community yet" branch, which already wraps both calls in its own
+// try/catch and falls back to needsSetup:true — so this guard is a
+// console-noise reduction, not a behavior fix.
 export function getDefaultRelayUrl(): Promise<string> {
+  if (!isTauri()) return Promise.reject(new Error("no Tauri runtime"));
   return invokeTauri<string>("get_default_relay_url");
 }
 
 export function autoConnectDefaultRelayEnabled(): Promise<boolean> {
+  if (!isTauri()) return Promise.resolve(false);
   return invokeTauri<boolean>("auto_connect_default_relay_enabled");
 }
 
+// Called unconditionally at app boot, before any Tauri-availability gate —
+// unlike most of this file's exports, which only run once the app has
+// already reached a native-only screen. Guard so it resolves cleanly to
+// `false` in a browser (web) runtime instead of throwing.
 export function isSharedIdentity(): Promise<boolean> {
+  if (!isTauri()) return Promise.resolve(false);
   return invokeTauri<boolean>("is_shared_identity");
 }
 
@@ -1188,8 +1199,14 @@ export async function validateReposDir(dir: string): Promise<void> {
   await invokeTauri("validate_repos_dir", { dir });
 }
 
+// Sleep prevention is a native OS concept with no browser equivalent.
+// usePreventSleep.ts calls this fire-and-forget (`void setPreventSleepActive(...)`)
+// with no .catch of its own, so an unguarded call here was a genuine unhandled
+// promise rejection in a web (non-Tauri) runtime — not just console noise.
 export const setPreventSleepActive = (active: boolean) =>
-  invokeTauri("set_prevent_sleep_active", { active });
+  isTauri()
+    ? invokeTauri("set_prevent_sleep_active", { active })
+    : Promise.resolve();
 
 export const setAgentManagedProfiles = (enabled: boolean) =>
   invokeTauri("set_agent_managed_profiles", { enabled });
diff --git a/desktop/src/shared/deep-link.ts b/desktop/src/shared/deep-link.ts
index c62a8bec3b..e491ee09a9 100644
--- a/desktop/src/shared/deep-link.ts
+++ b/desktop/src/shared/deep-link.ts
@@ -1,5 +1,5 @@
 import { listen, type UnlistenFn } from "@tauri-apps/api/event";
-import { invoke } from "@tauri-apps/api/core";
+import { invoke, isTauri } from "@tauri-apps/api/core";
 import type { StartCommunityOnboardingInput } from "@/features/onboarding/communityOnboarding";
 
 export type AddCommunityDeepLinkPayload = {
@@ -84,6 +84,11 @@ function acceptPendingCommunityDeepLink(
 }
 
 async function drainPendingCommunityDeepLinks(deps: DeepLinkDeps) {
+  // The pending-deep-link queue is populated by the Rust backend and only
+  // exists in the native Tauri shell — invoke() throws without Tauri
+  // internals in a browser (web) runtime.
+  if (!isTauri()) return;
+
   while (true) {
     const pending = await invoke<PendingCommunityDeepLink | null>(
       "take_pending_community_deep_link",
@@ -134,6 +139,17 @@ export async function listenForDeepLinks(
     })();
   };
   const stopAvailabilityListener = deps.onAddCommunityAvailable(drain);
+
+  // OS-level deep links (`buzz://…`) only exist in the native Tauri shell —
+  // `listen()` throws without Tauri internals in a browser (web) runtime.
+  // The in-app "add community available" wiring above still applies.
+  if (!isTauri()) {
+    drain();
+    return () => {
+      stopAvailabilityListener();
+    };
+  }
+
   const connectPromise = listen<string>("deep-link-connect", drain);
   const joinPromise = listen<JoinDeepLinkPayload>("deep-link-join", drain);
   const addCommunityPromise = listen<AddCommunityDeepLinkPayload>(
@@ -160,6 +176,8 @@ export async function listenForDeepLinks(
 export function listenForMessageDeepLinks(
   onOpen: (payload: MessageDeepLinkPayload) => void,
 ): Promise<UnlistenFn> {
+  // OS-level deep link — no-op outside the native Tauri shell.
+  if (!isTauri()) return Promise.resolve(() => {});
   return listen<MessageDeepLinkPayload>("deep-link-message", (event) => {
     onOpen(event.payload);
   });
@@ -168,6 +186,8 @@ export function listenForMessageDeepLinks(
 export function listenForNostrBindDeepLinks(
   onOpen: (payload: NostrBindDeepLinkPayload) => void,
 ): Promise<UnlistenFn> {
+  // OS-level deep link — no-op outside the native Tauri shell.
+  if (!isTauri()) return Promise.resolve(() => {});
   return listen<NostrBindDeepLinkPayload>("deep-link-nostr-bind", (event) => {
     onOpen(event.payload);
   });