diff --git a/packages/plugin-api/src/types.ts b/packages/plugin-api/src/types.ts
index 534aba3a6f..300793278c 100644
--- a/packages/plugin-api/src/types.ts
+++ b/packages/plugin-api/src/types.ts
@@ -347,21 +347,12 @@ export interface OAuthFlowConfig {
    */
   iosClientId?: string;
   /**
-   * Client ID for the web build (Google "Web application" client).
-   * Overrides `clientId` in the browser (non-Electron, non-native).
-   * The deployed origin's `/assets/oauth-callback.html` must be registered as an
-   * Authorized redirect URI on the Google Cloud Console OAuth client, and the
-   * deployed origin must be listed in Authorized JavaScript origins.
+   * Client ID for the web build, for providers that support public browser
+   * clients via Authorization Code + PKCE without a client secret.
+   * Overrides `clientId` in the browser (non-Electron, non-native) and omits
+   * `clientSecret`.
    */
   webClientId?: string;
-  /**
-   * Client secret paired with `webClientId`, sent on the token exchange.
-   * Required for IdPs (e.g. Google "Web application" clients) that classify
-   * web clients as confidential and reject PKCE-only exchanges. Ships in
-   * client-side JS like the auth code itself — only set this if you accept
-   * that the secret is visible to anyone running the web build.
-   */
-  webClientSecret?: string;
   scopes: string[];
   /** Additional query parameters to append to the authorization URL (e.g. access_type, prompt). */
   extraAuthParams?: Record<string, string>;
diff --git a/packages/plugin-dev/google-calendar-provider/src/plugin.spec.ts b/packages/plugin-dev/google-calendar-provider/src/plugin.spec.ts
index ac61763ded..8c958267f7 100644
--- a/packages/plugin-dev/google-calendar-provider/src/plugin.spec.ts
+++ b/packages/plugin-dev/google-calendar-provider/src/plugin.spec.ts
@@ -16,6 +16,16 @@ beforeAll(async () => {
 });
 
 describe('Google Calendar Plugin', () => {
+  describe('OAuth config', () => {
+    it('does not expose a browser web OAuth client', () => {
+      const oauthField = definition.configFields.find((field) => field.key === 'oauth');
+      const oauthConfig = oauthField?.oauthConfig as Record<string, unknown>;
+
+      expect(oauthConfig.webClientId).toBeUndefined();
+      expect(oauthConfig.webClientSecret).toBeUndefined();
+    });
+  });
+
   describe('fieldMappings', () => {
     const ctx = { issueId: 'event-1' };
 
@@ -309,7 +319,7 @@ describe('Google Calendar Plugin', () => {
       expect(body.start.date).toBeDefined();
       expect(body.end.date).toBeDefined();
       expect(body.start.dateTime).toBeUndefined();
-      expect(result.issueId).toBe('new-event-1');
+      expect(result.issueId).toBe('test-cal::new-event-1');
     });
   });
 });
diff --git a/packages/plugin-dev/google-calendar-provider/src/plugin.ts b/packages/plugin-dev/google-calendar-provider/src/plugin.ts
index 9159bba755..6badf4e971 100644
--- a/packages/plugin-dev/google-calendar-provider/src/plugin.ts
+++ b/packages/plugin-dev/google-calendar-provider/src/plugin.ts
@@ -37,20 +37,6 @@ const MOBILE_CLIENT_ID =
 // Requires "Custom URI scheme" to be enabled in Google Cloud Console.
 const IOS_CLIENT_ID =
   '637968426975-ka1muro7mee1go0m7hhog49fm7svr4os.apps.googleusercontent.com';
-// Web OAuth client — used by the browser build (app.super-productivity.com).
-// Google classifies "Web application" clients as confidential, so the token
-// endpoint rejects PKCE-only exchanges and we must ship the client_secret
-// alongside the auth code. Unlike CLIENT_SECRET above (which is RFC 8252-style
-// public for desktop apps), Google's policy formally requires this secret to
-// be kept confidential — embedding it in client-side JS deviates from policy
-// and the credential MAY be revoked by Google if abused.
-// In practice the actual security boundary is PKCE + the registered redirect
-// URI: a stolen secret cannot be used to redeem codes for a different origin.
-// The deployed origin's /assets/oauth-callback.html must be registered as an
-// Authorized redirect URI, and the origin itself in Authorized JavaScript origins.
-const WEB_CLIENT_ID =
-  '637968426975-6t6q988dk0417re8pcl06vq75obqq944.apps.googleusercontent.com';
-const WEB_CLIENT_SECRET = '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';
 
 // --- Config ---
 
@@ -286,8 +272,8 @@ PluginAPI.registerIssueProvider({
         clientSecret: CLIENT_SECRET,
         mobileClientId: MOBILE_CLIENT_ID,
         iosClientId: IOS_CLIENT_ID,
-        webClientId: WEB_CLIENT_ID,
-        webClientSecret: WEB_CLIENT_SECRET,
+        // Intentionally no webClientId: durable Google Calendar web OAuth
+        // requires a confidential client secret, which browser JS cannot keep.
         scopes: [CALENDAR_EVENTS_SCOPE, CALENDAR_READONLY_SCOPE],
         extraAuthParams: { access_type: 'offline', prompt: 'consent' },
       },
diff --git a/src/app/features/issue/dialog-edit-issue-provider/dialog-edit-issue-provider.component.html b/src/app/features/issue/dialog-edit-issue-provider/dialog-edit-issue-provider.component.html
index 3f4d2d3a77..c804cb9e4b 100644
--- a/src/app/features/issue/dialog-edit-issue-provider/dialog-edit-issue-provider.component.html
+++ b/src/app/features/issue/dialog-edit-issue-provider/dialog-edit-issue-provider.component.html
@@ -95,7 +95,20 @@
       }
       @for (btn of oauthButtons; track btn.label) {
         <div class="action-row">
-          @if (isOAuthConnected()) {
+          @if (isOAuthUnavailableInWeb(btn.oauthConfig)) {
+            <button
+              mat-stroked-button
+              type="button"
+              disabled
+            >
+              <mat-icon>block</mat-icon>
+              {{ btn.label }}
+            </button>
+            <span class="error-status">
+              <mat-icon class="error-status-icon">info</mat-icon>
+              {{ T.F.ISSUE.DIALOG.OAUTH_UNAVAILABLE_WEB | translate }}
+            </span>
+          } @else if (isOAuthConnected()) {
             <button
               mat-stroked-button
               type="button"
diff --git a/src/app/features/issue/dialog-edit-issue-provider/dialog-edit-issue-provider.component.ts b/src/app/features/issue/dialog-edit-issue-provider/dialog-edit-issue-provider.component.ts
index 204c9527cb..e7493ad92b 100644
--- a/src/app/features/issue/dialog-edit-issue-provider/dialog-edit-issue-provider.component.ts
+++ b/src/app/features/issue/dialog-edit-issue-provider/dialog-edit-issue-provider.component.ts
@@ -60,6 +60,7 @@ import { PluginIssueProviderRegistryService } from '../../../plugins/issue-provi
 import { PluginBridgeService } from '../../../plugins/plugin-bridge.service';
 import { PluginHttpService } from '../../../plugins/issue-provider/plugin-http.service';
 import { OAuthFlowConfig } from '@super-productivity/plugin-api';
+import { IS_NATIVE_PLATFORM } from '../../../util/is-native-platform';
 import { TrelloAdditionalCfgComponent } from '../providers/trello/trello-view-components/trello_cfg/trello_additional_cfg.component';
 // ClickUp is now a plugin — no built-in config component needed
 import { NextcloudDeckAdditionalCfgComponent } from '../providers/nextcloud-deck/nextcloud-deck-additional-cfg.component';
@@ -350,6 +351,9 @@ export class DialogEditIssueProviderComponent {
   }
 
   async connectOAuth(oauthConfig: OAuthFlowConfig): Promise<void> {
+    if (this.isOAuthUnavailableInWeb(oauthConfig)) {
+      return;
+    }
     const pluginId = this._pluginRegistry.getProvider(this.issueProviderKey)?.pluginId;
     if (!pluginId) {
       return;
@@ -395,6 +399,10 @@ export class DialogEditIssueProviderComponent {
   protected readonly IS_ELECTRON = IS_ELECTRON;
   protected readonly IS_WEB_EXTENSION_REQUIRED_FOR_JIRA = IS_WEB_BROWSER;
 
+  protected isOAuthUnavailableInWeb(oauthConfig: OAuthFlowConfig): boolean {
+    return !IS_ELECTRON && !IS_NATIVE_PLATFORM && !oauthConfig.webClientId;
+  }
+
   /**
    * @returns true if all fields loaded successfully, false if any failed
    */
diff --git a/src/app/plugins/oauth/plugin-oauth-bridge.service.spec.ts b/src/app/plugins/oauth/plugin-oauth-bridge.service.spec.ts
new file mode 100644
index 0000000000..e5c65ae36c
--- /dev/null
+++ b/src/app/plugins/oauth/plugin-oauth-bridge.service.spec.ts
@@ -0,0 +1,114 @@
+import { TestBed } from '@angular/core/testing';
+import { Subject } from 'rxjs';
+import type { OAuthFlowConfig } from '@super-productivity/plugin-api';
+import { PluginOAuthBridgeService } from './plugin-oauth-bridge.service';
+import { PluginOAuthService } from './plugin-oauth.service';
+
+describe('PluginOAuthBridgeService', () => {
+  let service: PluginOAuthBridgeService;
+  let oauthService: jasmine.SpyObj<PluginOAuthService>;
+
+  const baseConfig: OAuthFlowConfig = {
+    authUrl: 'https://accounts.google.com/o/oauth2/v2/auth',
+    tokenUrl: 'https://oauth2.googleapis.com/token',
+    clientId: 'desktop-client-id',
+    clientSecret: 'desktop-client-secret',
+    scopes: ['calendar.readonly'],
+  };
+
+  beforeEach(() => {
+    oauthService = jasmine.createSpyObj<PluginOAuthService>(
+      'PluginOAuthService',
+      [
+        'validateOAuthConfig',
+        'getRedirectUri',
+        'buildAuthUrl',
+        'waitForRedirectCode',
+        'exchangeCodeForTokens',
+        'storeTokens',
+        'serializeTokens',
+        'clearTokens',
+        'hasTokens',
+        'restoreTokens',
+        'getValidToken',
+      ],
+      { tokenInvalidated$: new Subject<string>() },
+    );
+
+    TestBed.configureTestingModule({
+      providers: [
+        PluginOAuthBridgeService,
+        { provide: PluginOAuthService, useValue: oauthService },
+      ],
+    });
+
+    service = TestBed.inject(PluginOAuthBridgeService);
+  });
+
+  it('rejects browser OAuth when a plugin has no web client id', async () => {
+    await expectAsync(
+      service.startOAuthFlow('google-calendar', baseConfig),
+    ).toBeRejectedWithError(/not available in the web build/);
+
+    expect(oauthService.validateOAuthConfig).toHaveBeenCalledWith(baseConfig);
+    expect(oauthService.getRedirectUri).not.toHaveBeenCalled();
+  });
+
+  it('uses a public web client id without carrying the desktop client secret', async () => {
+    spyOn(window, 'open').and.returnValue({} as Window);
+    oauthService.getRedirectUri.and.resolveTo(
+      'https://app.super-productivity.com/assets/oauth-callback.html',
+    );
+    oauthService.buildAuthUrl.and.resolveTo({
+      url: 'https://accounts.google.com/o/oauth2/v2/auth',
+      codeVerifier: 'verifier',
+      state: 'state',
+    });
+    oauthService.waitForRedirectCode.and.resolveTo('auth-code');
+    oauthService.exchangeCodeForTokens.and.resolveTo({
+      accessToken: 'access-token',
+      refreshToken: 'refresh-token',
+      expiresAt: Date.now() + 3600000,
+    });
+    oauthService.serializeTokens.and.returnValue(null);
+
+    await service.startOAuthFlow('pkce-web-provider', {
+      ...baseConfig,
+      webClientId: 'web-client-id',
+    });
+
+    const effectiveConfig = oauthService.buildAuthUrl.calls.mostRecent()
+      .args[0] as OAuthFlowConfig;
+    expect(effectiveConfig.clientId).toBe('web-client-id');
+    expect(effectiveConfig.clientSecret).toBeUndefined();
+    expect(oauthService.exchangeCodeForTokens).toHaveBeenCalledWith(
+      jasmine.objectContaining({
+        clientId: 'web-client-id',
+        clientSecret: undefined,
+      }),
+    );
+  });
+
+  it('clears stale browser tokens for providers that are unavailable on web', async () => {
+    oauthService.hasTokens.and.returnValue(true);
+
+    const hasTokens = await service.restoreAndCheckOAuthTokens(
+      'google-calendar',
+      baseConfig,
+    );
+
+    expect(hasTokens).toBeFalse();
+    expect(oauthService.clearTokens).toHaveBeenCalledWith('google-calendar');
+    expect(oauthService.getValidToken).not.toHaveBeenCalled();
+  });
+
+  it('does not return stale browser tokens for providers that are unavailable on web', async () => {
+    oauthService.hasTokens.and.returnValue(true);
+
+    const token = await service.getOAuthToken('google-calendar', baseConfig);
+
+    expect(token).toBeNull();
+    expect(oauthService.clearTokens).toHaveBeenCalledWith('google-calendar');
+    expect(oauthService.getValidToken).not.toHaveBeenCalled();
+  });
+});
diff --git a/src/app/plugins/oauth/plugin-oauth-bridge.service.ts b/src/app/plugins/oauth/plugin-oauth-bridge.service.ts
index 294cfca0c7..83becbd98c 100644
--- a/src/app/plugins/oauth/plugin-oauth-bridge.service.ts
+++ b/src/app/plugins/oauth/plugin-oauth-bridge.service.ts
@@ -47,7 +47,7 @@ export class PluginOAuthBridgeService {
     // Pick the platform-specific client. The default `clientId` is the desktop
     // client (loopback redirect, used by Electron); other platforms override it.
     // - Android/iOS authenticate via app signing → no client secret
-    // - Web uses an IdP-specific "Web application" client → may ship a secret
+    // - Web can only use providers that support public browser clients via PKCE
     // Order matters: Android-WebView sets both IS_ANDROID_NATIVE and IS_NATIVE_PLATFORM,
     // so it lands in the Android branch (correct) and never reaches the web branch.
     const effectiveConfig = ((): OAuthFlowConfig => {
@@ -58,15 +58,16 @@ export class PluginOAuthBridgeService {
         return { ...config, clientId: config.iosClientId, clientSecret: undefined };
       }
       if (!IS_ELECTRON && !IS_NATIVE_PLATFORM) {
-        if (!config.webClientId) {
+        const webClientId = config.webClientId;
+        if (!webClientId) {
           throw new Error(
-            'OAuth: this plugin does not support the web build (no webClientId configured). Connect from the desktop or mobile app instead.',
+            'OAuth: this plugin is not available in the web build. Connect from the desktop or mobile app instead.',
           );
         }
         return {
           ...config,
-          clientId: config.webClientId,
-          clientSecret: config.webClientSecret,
+          clientId: webClientId,
+          clientSecret: undefined,
         };
       }
       return config;
@@ -108,20 +109,38 @@ export class PluginOAuthBridgeService {
     await this._clearPersistedOAuthTokens(pluginId);
   }
 
-  async restoreAndCheckOAuthTokens(pluginId: string): Promise<boolean> {
+  async restoreAndCheckOAuthTokens(
+    pluginId: string,
+    config?: OAuthFlowConfig,
+  ): Promise<boolean> {
+    if (this._isUnavailableInWeb(config)) {
+      await this.clearOAuthTokens(pluginId);
+      return false;
+    }
     if (!this._pluginOAuthService.hasTokens(pluginId)) {
       await this._restoreOAuthTokens(pluginId);
     }
     return this._pluginOAuthService.hasTokens(pluginId);
   }
 
-  async getOAuthToken(pluginId: string): Promise<string | null> {
+  async getOAuthToken(
+    pluginId: string,
+    config?: OAuthFlowConfig,
+  ): Promise<string | null> {
+    if (this._isUnavailableInWeb(config)) {
+      await this.clearOAuthTokens(pluginId);
+      return null;
+    }
     if (!this._pluginOAuthService.hasTokens(pluginId)) {
       await this._restoreOAuthTokens(pluginId);
     }
     return this._pluginOAuthService.getValidToken(pluginId);
   }
 
+  private _isUnavailableInWeb(config?: OAuthFlowConfig): boolean {
+    return !!config && !IS_ELECTRON && !IS_NATIVE_PLATFORM && !config.webClientId;
+  }
+
   private _openOAuthWindow(url: string): void {
     if (IS_ELECTRON) {
       window.ea.pluginOAuthStart(url);
diff --git a/src/app/plugins/oauth/plugin-oauth.model.ts b/src/app/plugins/oauth/plugin-oauth.model.ts
index 61a597dbf8..5d660b900c 100644
--- a/src/app/plugins/oauth/plugin-oauth.model.ts
+++ b/src/app/plugins/oauth/plugin-oauth.model.ts
@@ -4,5 +4,5 @@ export interface PluginOAuthTokens {
   expiresAt: number; // unix ms
   tokenUrl: string; // needed for refresh
   clientId: string; // needed for refresh
-  clientSecret?: string; // needed for refresh (Google requires it)
+  clientSecret?: string; // optional non-confidential installed-app secret for refresh
 }
diff --git a/src/app/plugins/plugin-bridge.service.ts b/src/app/plugins/plugin-bridge.service.ts
index 2630107414..44f85ab84b 100644
--- a/src/app/plugins/plugin-bridge.service.ts
+++ b/src/app/plugins/plugin-bridge.service.ts
@@ -260,7 +260,10 @@ export class PluginBridgeService implements OnDestroy {
       startOAuthFlow: (config: OAuthFlowConfig): Promise<OAuthTokenResult> =>
         this._pluginOAuthBridge.startOAuthFlow(pluginId, config),
       getOAuthToken: (): Promise<string | null> =>
-        this._pluginOAuthBridge.getOAuthToken(pluginId),
+        this._pluginOAuthBridge.getOAuthToken(
+          pluginId,
+          this._getOAuthConfigForPlugin(pluginId),
+        ),
       clearOAuthToken: (): Promise<void> =>
         this._pluginOAuthBridge.clearOAuthTokens(pluginId),
 
@@ -370,7 +373,20 @@ export class PluginBridgeService implements OnDestroy {
   }
 
   async restoreAndCheckOAuthTokens(pluginId: string): Promise<boolean> {
-    return this._pluginOAuthBridge.restoreAndCheckOAuthTokens(pluginId);
+    return this._pluginOAuthBridge.restoreAndCheckOAuthTokens(
+      pluginId,
+      this._getOAuthConfigForPlugin(pluginId),
+    );
+  }
+
+  private _getOAuthConfigForPlugin(pluginId: string): OAuthFlowConfig | undefined {
+    const registeredKey = this._pluginIssueProviderRegistry.getRegisteredKey(pluginId);
+    if (!registeredKey) {
+      return undefined;
+    }
+    return this._pluginIssueProviderRegistry
+      .getConfigFields(registeredKey)
+      .find((f) => f.type === 'oauthButton' && f.oauthConfig)?.oauthConfig;
   }
 
   private async _downloadFile(filename: string, data: string): Promise<void> {
diff --git a/src/app/t.const.ts b/src/app/t.const.ts
index c73007213c..d704d948e6 100644
--- a/src/app/t.const.ts
+++ b/src/app/t.const.ts
@@ -488,6 +488,7 @@ const T = {
         LOAD_OPTIONS: 'F.ISSUE.DIALOG.LOAD_OPTIONS',
         LOAD_OPTIONS_FAILED: 'F.ISSUE.DIALOG.LOAD_OPTIONS_FAILED',
         LOADING_OPTIONS: 'F.ISSUE.DIALOG.LOADING_OPTIONS',
+        OAUTH_UNAVAILABLE_WEB: 'F.ISSUE.DIALOG.OAUTH_UNAVAILABLE_WEB',
         OPTIONS_LOADED: 'F.ISSUE.DIALOG.OPTIONS_LOADED',
         RELOAD_OPTIONS: 'F.ISSUE.DIALOG.RELOAD_OPTIONS',
         SETUP_TITLE: 'F.ISSUE.DIALOG.SETUP_TITLE',
diff --git a/src/assets/i18n/en.json b/src/assets/i18n/en.json
index 16656de2fe..bc8afafbf8 100644
--- a/src/assets/i18n/en.json
+++ b/src/assets/i18n/en.json
@@ -488,6 +488,7 @@
         "LOAD_OPTIONS": "Load Options",
         "LOAD_OPTIONS_FAILED": "Failed to load options",
         "LOADING_OPTIONS": "Loading options...",
+        "OAUTH_UNAVAILABLE_WEB": "Available in the desktop and mobile apps. Synced settings stay saved, but live data cannot be loaded in the web app.",
         "OPTIONS_LOADED": "Options loaded",
         "RELOAD_OPTIONS": "Reload Options",
         "SETUP_TITLE": "Setup {{title}} Config",