diff --git a/.changeset/fn-7473-desktop-anthropic-oauth-browser.md b/.changeset/fn-7473-desktop-anthropic-oauth-browser.md
new file mode 100644
index 0000000000..0ba9284e63
--- /dev/null
+++ b/.changeset/fn-7473-desktop-anthropic-oauth-browser.md
@@ -0,0 +1,7 @@
+---
+"@runfusion/fusion": patch
+---
+
+summary: Open desktop Anthropic Subscription OAuth logins in the system browser.
+category: fix
+dev: Adds Electron window-open policy coverage and preserves Settings auth polling completion paths.
diff --git a/docs/dashboard-guide.md b/docs/dashboard-guide.md
index c993aee024..a4c3880e82 100644
--- a/docs/dashboard-guide.md
+++ b/docs/dashboard-guide.md
@@ -638,7 +638,7 @@ The global OAuth re-login banner clears a provider row immediately after that pr
 
 For Claude/Anthropic OAuth credentials, the same `/auth/status` poll also attempts an automatic refresh when the stored OAuth credential has a refresh token and the access token is expired or within the refresh buffer. Anthropic banner state is keyed to `anthropic-subscription` (including legacy Anthropic OAuth rows), not Claude CLI state. When that refresh succeeds, the banner clears for the subscription provider without manual re-login and without waiting for a separate model request.
 
-If the OAuth credential has no refresh token, the refresh request fails, or the provider is not Anthropic, the provider stays expired and the banner remains visible. Re-authenticate with manual re-login from **Settings → Authentication** or Model Onboarding.
+If the OAuth credential has no refresh token, the refresh request fails, or the provider is not Anthropic, the provider stays expired and the banner remains visible. Re-authenticate with manual re-login from **Settings → Authentication** or Model Onboarding. On Fusion desktop, OAuth login URLs open in the operating system browser rather than an in-app Electron child window; the Settings/Onboarding UI keeps polling until the provider authenticates or the login truly stops.
 
 Anthropic also supports a raw `ANTHROPIC_API_KEY` from a separate **Anthropic API Key** card in **Settings → Authentication** and Model Onboarding. Claude subscription OAuth remains on the **Anthropic Subscription** card for auth status, usage/subscription checks, and banner clearing; it also drives direct agent execution on the `anthropic` provider — a subscription/OAuth token runs `anthropic/*` selections against `https://api.anthropic.com/v1` with Claude Code identity headers, no API key required. CLI-backed execution remains the distinct, explicit **Claude CLI** provider (`pi-claude-cli`); subscription OAuth does not require it. When Anthropic Subscription is expired but Anthropic API Key or Anthropic — via Claude CLI is already authenticated, the global banner suppresses only the urgent subscription re-login entry so it does not imply agents are blocked; Settings still shows the subscription OAuth card as expired/not connected and re-login remains available. A configured API key takes precedence over OAuth on the direct provider. Saving or clearing an API key does not affect the OAuth sign-in path or turn OAuth tokens into raw API-key material. The dashboard only displays masked key hints after a key is saved.
 
diff --git a/docs/settings-reference.md b/docs/settings-reference.md
index 33ef7436ad..44ed8b961e 100644
--- a/docs/settings-reference.md
+++ b/docs/settings-reference.md
@@ -755,7 +755,7 @@ Anthropic has three independent authentication/routing paths:
 - **Claude CLI** (`pi-claude-cli`) is the CLI-backed execution provider. Use it when you want sessions to run through the local `claude` CLI; CLI availability does not prove the subscription OAuth status is valid. It is a separate, explicit choice — subscription OAuth does not require or reroute to it. When Claude CLI is enabled, model selectors show the registered `pi-claude-cli/*` rows (for example `pi-claude-cli/claude-sonnet-5`) in addition to the direct `anthropic/*` rows.
 - **Anthropic API Key** (`anthropic` direct `/v1`) is raw API-key auth. It accepts `ANTHROPIC_API_KEY`, a `models.json` `apiKey`, or an `api_key` auth credential, uses `x-api-key`, and takes precedence over subscription OAuth when both are configured for the direct `https://api.anthropic.com/v1` provider.
 
-Anthropic can be connected with a raw API key from both Model Onboarding and **Settings → Authentication**. Anthropic API-key auth appears as a separate **Anthropic API Key** card, while Claude subscription OAuth appears as **Anthropic Subscription** with Login/Logout controls. `/api/auth/status` returns only masked key hints for the API-key card.
+Anthropic can be connected with a raw API key from both Model Onboarding and **Settings → Authentication**. Anthropic API-key auth appears as a separate **Anthropic API Key** card, while Claude subscription OAuth appears as **Anthropic Subscription** with Login/Logout controls. On Fusion desktop, Anthropic Subscription OAuth login URLs are delegated to the operating system browser instead of an Electron child window so the existing polling/callback flow can complete. `/api/auth/status` returns only masked key hints for the API-key card.
 
 ### Authentication troubleshooting (mobile OAuth fallback)
 
diff --git a/packages/dashboard/app/components/__tests__/SettingsModal.models-auth.test.tsx b/packages/dashboard/app/components/__tests__/SettingsModal.models-auth.test.tsx
index 9f6d345c74..d450f9c3da 100644
--- a/packages/dashboard/app/components/__tests__/SettingsModal.models-auth.test.tsx
+++ b/packages/dashboard/app/components/__tests__/SettingsModal.models-auth.test.tsx
@@ -1133,6 +1133,82 @@ describe("SettingsModal", () => {
       });
     });
 
+    it("keeps polling Anthropic Subscription OAuth until authenticated without false incomplete toast", async () => {
+      const openSpy = vi.spyOn(window, "open").mockImplementation(() => null);
+      const addToast = vi.fn();
+      mockFetchAuthStatus
+        .mockResolvedValueOnce({
+          providers: [{ id: "anthropic-subscription", name: "Anthropic Subscription", authenticated: false, type: "oauth" }],
+        })
+        .mockResolvedValueOnce({
+          providers: [{ id: "anthropic-subscription", name: "Anthropic Subscription", authenticated: false, type: "oauth", loginInProgress: true }],
+        })
+        .mockResolvedValueOnce({
+          providers: [{ id: "anthropic-subscription", name: "Anthropic Subscription", authenticated: true, type: "oauth", loginInProgress: false }],
+        });
+      mockLoginProvider.mockResolvedValueOnce({ url: "https://claude.ai/oauth/authorize" });
+
+      render(<SettingsModal onClose={noop} addToast={addToast} />);
+      await waitForSettingsModalReady();
+      await settingsModalUser.click(screen.getByRole("button", { name: "Authentication" }));
+      vi.useFakeTimers();
+
+      try {
+        const anthropicCard = screen.getByTestId("auth-provider-icon-anthropic-subscription").closest(".auth-provider-card") as HTMLElement;
+        fireEvent.click(within(anthropicCard).getByRole("button", { name: "Login" }));
+
+        await act(async () => {
+          await Promise.resolve();
+        });
+        expect(openSpy).toHaveBeenCalledWith("https://claude.ai/oauth/authorize", "_blank");
+        await act(async () => {
+          await vi.advanceTimersByTimeAsync(2000);
+          await vi.advanceTimersByTimeAsync(2000);
+        });
+
+        expect(addToast).toHaveBeenCalledWith("Login successful", "success");
+        expect(addToast).not.toHaveBeenCalledWith("Login did not complete. Please try again.", "error");
+      } finally {
+        vi.useRealTimers();
+      }
+    });
+
+    it("shows incomplete toast when Anthropic Subscription OAuth stops without authentication", async () => {
+      const openSpy = vi.spyOn(window, "open").mockImplementation(() => null);
+      const addToast = vi.fn();
+      mockFetchAuthStatus
+        .mockResolvedValueOnce({
+          providers: [{ id: "anthropic-subscription", name: "Anthropic Subscription", authenticated: false, type: "oauth" }],
+        })
+        .mockResolvedValueOnce({
+          providers: [{ id: "anthropic-subscription", name: "Anthropic Subscription", authenticated: false, type: "oauth", loginInProgress: false }],
+        });
+      mockLoginProvider.mockResolvedValueOnce({ url: "https://claude.ai/oauth/authorize" });
+
+      render(<SettingsModal onClose={noop} addToast={addToast} />);
+      await waitForSettingsModalReady();
+      await settingsModalUser.click(screen.getByRole("button", { name: "Authentication" }));
+      vi.useFakeTimers();
+
+      try {
+        const anthropicCard = screen.getByTestId("auth-provider-icon-anthropic-subscription").closest(".auth-provider-card") as HTMLElement;
+        fireEvent.click(within(anthropicCard).getByRole("button", { name: "Login" }));
+
+        await act(async () => {
+          await Promise.resolve();
+        });
+        expect(openSpy).toHaveBeenCalledWith("https://claude.ai/oauth/authorize", "_blank");
+        await act(async () => {
+          await vi.advanceTimersByTimeAsync(2000);
+        });
+
+        expect(addToast).toHaveBeenCalledWith("Login did not complete. Please try again.", "error");
+        expect(addToast).not.toHaveBeenCalledWith("Login successful", "success");
+      } finally {
+        vi.useRealTimers();
+      }
+    });
+
     it("renders Anthropic pasted-code form when login response includes manualCode", async () => {
       const openSpy = vi.spyOn(window, "open").mockImplementation(() => null);
       mockFetchAuthStatus.mockResolvedValueOnce({
diff --git a/packages/desktop/src/__tests__/main-integration.test.ts b/packages/desktop/src/__tests__/main-integration.test.ts
index 85cbe0501b..800b149717 100644
--- a/packages/desktop/src/__tests__/main-integration.test.ts
+++ b/packages/desktop/src/__tests__/main-integration.test.ts
@@ -25,6 +25,7 @@ const mocks = vi.hoisted(() => {
       show: vi.fn(),
       focus: vi.fn(),
       maximize: vi.fn(),
+      webContents: { setWindowOpenHandler: vi.fn() },
       isDestroyed: vi.fn(() => false),
       getBounds: vi.fn(() => ({ x: 50, y: 80, width: 1280, height: 900 })),
       isMaximized: vi.fn(() => false),
@@ -169,6 +170,7 @@ vi.mock("electron", () => ({
   Tray: mocks.Tray,
   nativeImage: mocks.nativeImage,
   screen: mocks.screen,
+  shell: { openExternal: vi.fn(() => Promise.resolve()) },
 }));
 
 vi.mock("../menu.js", () => ({
diff --git a/packages/desktop/src/__tests__/main-local-mode.test.ts b/packages/desktop/src/__tests__/main-local-mode.test.ts
index 61334a98df..288d7c599a 100644
--- a/packages/desktop/src/__tests__/main-local-mode.test.ts
+++ b/packages/desktop/src/__tests__/main-local-mode.test.ts
@@ -24,7 +24,7 @@ const mocks = vi.hoisted(() => {
     show: vi.fn(),
     focus: vi.fn(),
     maximize: vi.fn(),
-    webContents: { send: vi.fn() },
+    webContents: { send: vi.fn(), setWindowOpenHandler: vi.fn() },
   };
 
   const BrowserWindow = vi.fn(function () {
@@ -70,6 +70,7 @@ vi.mock("electron", () => ({
   Tray: mocks.Tray,
   nativeImage: { createEmpty: vi.fn(() => ({})) },
   screen: mocks.screen,
+  shell: { openExternal: vi.fn(() => Promise.resolve()) },
 }));
 
 vi.mock("../renderer.js", () => ({ isUrlRenderer: vi.fn(() => true), getRendererUrl: vi.fn(() => "http://localhost"), getRendererFilePath: vi.fn(() => "index.html") }));
diff --git a/packages/desktop/src/__tests__/main.integration.test.ts b/packages/desktop/src/__tests__/main.integration.test.ts
index ad1335b75e..8758b8b1c9 100644
--- a/packages/desktop/src/__tests__/main.integration.test.ts
+++ b/packages/desktop/src/__tests__/main.integration.test.ts
@@ -17,6 +17,7 @@ const mocks = vi.hoisted(() => {
     show: vi.fn(),
     focus: vi.fn(),
     maximize: vi.fn(),
+    webContents: { setWindowOpenHandler: vi.fn() },
   };
 
   return {
@@ -59,6 +60,7 @@ vi.mock("electron", () => ({
   Tray: mocks.Tray,
   nativeImage: mocks.nativeImage,
   screen: mocks.screen,
+  shell: { openExternal: vi.fn(() => Promise.resolve()) },
 }));
 
 vi.mock("../menu.js", () => ({
diff --git a/packages/desktop/src/__tests__/main.test.ts b/packages/desktop/src/__tests__/main.test.ts
index 9bd54c3b6f..b10108edf3 100644
--- a/packages/desktop/src/__tests__/main.test.ts
+++ b/packages/desktop/src/__tests__/main.test.ts
@@ -42,7 +42,12 @@ const mocks = vi.hoisted(() => {
     hide: vi.fn(),
     close: vi.fn(),
     maximize: vi.fn(),
-    webContents: { reload: vi.fn() },
+    webContents: {
+      reload: vi.fn(),
+      setWindowOpenHandler: vi.fn((handler: (details: { url: string }) => unknown) => {
+        browserWindowHandlers.set("window-open", handler as (...args: unknown[]) => void);
+      }),
+    },
   };
 
   const BrowserWindow = vi.fn(function () {
@@ -326,6 +331,53 @@ describe("main process", () => {
     expect(mocks.browserWindowInstance.loadURL).not.toHaveBeenCalled();
   });
 
+  it("macOS Anthropic Subscription OAuth denies Claude app-like popup and opens system browser", async () => {
+    const authUrl = "https://claude.ai/oauth/authorize?client_id=fusion&redirect_uri=http%3A%2F%2Flocalhost%3A1455%2Fcallback";
+    const { createMainWindow } = await importMainModule();
+
+    createMainWindow();
+    const handler = mocks.browserWindowHandlers.get("window-open") as
+      | ((details: { url: string }) => { action: "allow" | "deny" })
+      | undefined;
+
+    expect(handler).toBeTypeOf("function");
+    const result = handler?.({ url: authUrl });
+
+    expect(result).toEqual({ action: "deny" });
+    expect(mocks.shell.openExternal).toHaveBeenCalledTimes(1);
+    expect(mocks.shell.openExternal).toHaveBeenCalledWith(authUrl);
+  });
+
+  it("keeps same-origin Fusion renderer popups inside the desktop app", async () => {
+    rendererMocks.isUrlRenderer.mockReturnValue(true);
+    rendererMocks.getRendererUrl.mockReturnValue("http://localhost:5173");
+    rendererMocks.getRendererFilePath.mockReturnValue("");
+    const { createMainWindow } = await importMainModule();
+
+    createMainWindow();
+    const handler = mocks.browserWindowHandlers.get("window-open") as
+      | ((details: { url: string }) => { action: "allow" | "deny" })
+      | undefined;
+
+    const result = handler?.({ url: "http://localhost:5173/settings?section=auth" });
+
+    expect(result).toEqual({ action: "allow" });
+    expect(mocks.shell.openExternal).not.toHaveBeenCalled();
+  });
+
+  it("does not externalize Fusion deep links or unsafe custom window-open schemes", async () => {
+    const { createMainWindow } = await importMainModule();
+
+    createMainWindow();
+    const handler = mocks.browserWindowHandlers.get("window-open") as
+      | ((details: { url: string }) => { action: "allow" | "deny" })
+      | undefined;
+
+    expect(handler?.({ url: "fusion://task/FN-7473" })).toEqual({ action: "deny" });
+    expect(handler?.({ url: "claude://oauth/callback?code=abc" })).toEqual({ action: "deny" });
+    expect(mocks.shell.openExternal).not.toHaveBeenCalled();
+  });
+
   it("exports initializeApp for lifecycle orchestration", async () => {
     const mainModule = await importMainModule();
 
diff --git a/packages/desktop/src/main.ts b/packages/desktop/src/main.ts
index 26b31067d8..1b5e1d57a0 100644
--- a/packages/desktop/src/main.ts
+++ b/packages/desktop/src/main.ts
@@ -1,4 +1,4 @@
-import { app, BrowserWindow, nativeImage, screen, Tray } from "electron";
+import { app, BrowserWindow, nativeImage, screen, shell, Tray } from "electron";
 import { join, resolve } from "node:path";
 import { fileURLToPath } from "node:url";
 import os from "node:os";
@@ -99,6 +99,37 @@ export function getCurrentDesktopLaunchMode(): DesktopLaunchMode {
   return currentDesktopLaunchMode;
 }
 
+function isLoopbackHost(hostname: string): boolean {
+  const normalized = hostname.toLowerCase();
+  return normalized === "localhost" || normalized === "127.0.0.1" || normalized === "::1" || normalized === "[::1]";
+}
+
+function getDesktopRendererOrigin(launchTargetUrl?: string): string | null {
+  const candidateUrl = launchTargetUrl ?? (isUrlRenderer() ? getRendererUrl() : `file://${getRendererFilePath()}`);
+  try {
+    return new URL(candidateUrl).origin;
+  } catch {
+    return null;
+  }
+}
+
+function isInternalDesktopNavigation(url: URL, rendererOrigin: string | null): boolean {
+  if (url.protocol === "file:") {
+    return true;
+  }
+
+  if ((url.protocol === "http:" || url.protocol === "https:") && rendererOrigin && url.origin === rendererOrigin) {
+    return true;
+  }
+
+  // Local runtime/dev dashboard URLs represent Fusion app navigation, not external OAuth destinations.
+  if ((url.protocol === "http:" || url.protocol === "https:") && isLoopbackHost(url.hostname)) {
+    return true;
+  }
+
+  return false;
+}
+
 async function resetLaunchModeAndReload(window: BrowserWindow): Promise<void> {
   try {
     const settings = await readShellSettings();
@@ -148,6 +179,33 @@ export function createMainWindow(state?: WindowState, launchTargetUrl?: string):
     },
   });
 
+  const rendererOrigin = getDesktopRendererOrigin(launchTargetUrl);
+  window.webContents.setWindowOpenHandler(({ url }) => {
+    let parsedUrl: URL;
+    try {
+      parsedUrl = new URL(url);
+    } catch {
+      return { action: "deny" };
+    }
+
+    if (isInternalDesktopNavigation(parsedUrl, rendererOrigin)) {
+      return { action: "allow" };
+    }
+
+    if (parsedUrl.protocol === "http:" || parsedUrl.protocol === "https:") {
+      /*
+      FNXC:DesktopOAuth 2026-07-03-15:55:
+      macOS Anthropic Subscription login must leave the Electron popup path and open in the user's system browser instead of a child BrowserWindow or Claude Code app handoff. Keep Fusion polling in the renderer while denying the popup so the OAuth callback can complete the existing login state.
+      */
+      void shell.openExternal(url).catch((error: unknown) => {
+        console.error(`[desktop/main] Failed to open external URL: ${url}`, error);
+      });
+      return { action: "deny" };
+    }
+
+    return { action: "deny" };
+  });
+
   if (launchTargetUrl) {
     void window.loadURL(launchTargetUrl);
   } else if (isUrlRenderer()) {