app/src/components/projects/home/BrowserTab.tsx

@@ -23,6 +23,7 @@ import {
   setBrowserViewMatchWindow,
   setBrowserViewPopoutAlwaysOnTop,
 } from "../../../lib/tauri-commands";
+import { isBrowserViewUsable } from "../../../lib/browserViewSupport";
 import { useAppState } from "../../../store/appState";
 import OpenPageDialog from "./OpenPageDialog";
 import AccordionSection from "../../ui/AccordionSection";
@@ -338,7 +339,7 @@ export default function BrowserTab({ project, active }: Props) {
   // Prefer the probe: it is the fresher of the two, and it is the one that
   // reflects an install that just finished.
   const probed = detection ?? status.detection;
-  const ready = isUsable(probed);
+  const ready = isBrowserViewUsable(probed);
   // Mirrors Rust `PlaywrightDetection::needs_browser`: the Chrome channel is an
   // apt package, so it never shows up in `browsers`, and a container that has
   // it is not missing a browser.
@@ -539,11 +540,6 @@ export default function BrowserTab({ project, active }: Props) {
   );
 }
 
-/** Mirrors Rust `PlaywrightDetection::is_usable`. */
-function isUsable(d: PlaywrightDetection | null): boolean {
-  return d !== null && d.playwright_version !== null && d.has_bind && d.cli_entry !== null;
-}
-
 /**
  * Mirrors Rust `PlaywrightDetection::revision_skew`.
  *
@@ -627,7 +623,7 @@ function Setup({
   onInstall: (which: Exclude<SetupJob, null>) => void;
 }) {
   const busy = job !== null;
-  const havePackages = isUsable(detection);
+  const havePackages = isBrowserViewUsable(detection);
   const missing = missingParts(detection);
   const browsers = detection?.browsers ?? [];
   const chrome = detection?.chrome_channel ?? null;

app/src/components/terminal/TerminalView.test.tsx

@@ -3,6 +3,12 @@ import { render, fireEvent, cleanup, act } from "@testing-library/react";
 import TerminalView, { supersedes } from "./TerminalView";
 import { useAppState } from "../../store/appState";
 import { uploadHostFileToTerminal } from "../../lib/tauri-commands";
+import { openUrl } from "@tauri-apps/plugin-opener";
+import {
+  chooseSignInTarget,
+  resetBrowserSupportCache,
+} from "../../hooks/useSignInOpenTarget";
+import type { AuthBridgeStatus, PlaywrightDetection } from "../../lib/types";
 import { URL_TOAST_SELECTOR } from "./UrlToast";
 
 /**
@@ -16,6 +22,18 @@ const dragDrop = vi.hoisted(() => ({
   handler: null as null | ((event: unknown) => unknown),
 }));
 
+/**
+ * What the project's container answers about itself.
+ *
+ * `TerminalView` asks two questions on mount — is the auth bridge live, and is
+ * there a browser inside to open a page in — because together they decide which
+ * of the URL toast's two buttons leads for a sign-in link.
+ */
+const containerEnv = vi.hoisted(() => ({
+  bridge: { enabled: false, active_ports: [], conflicts: [] } as unknown,
+  detection: null as unknown,
+}));
+
 /** The `terminal-output-{id}` listeners, so a test can be the PTY. */
 const ptyOutput = vi.hoisted(() => ({
   listeners: new Map<string, (e: { payload: number[] }) => void>(),
@@ -45,6 +63,8 @@ vi.mock("../../lib/tauri-commands", () => ({
   awsSsoRefresh: vi.fn(async () => {}),
   openPageInContainerBrowser: vi.fn(async () => ({ error: null })),
   uploadHostFileToTerminal: vi.fn(async () => ""),
+  getAuthBridgeStatus: vi.fn(async () => containerEnv.bridge),
+  checkBrowserViewSupport: vi.fn(async () => containerEnv.detection),
 }));
 
 vi.mock("@tauri-apps/api/event", () => ({
@@ -128,6 +148,14 @@ beforeEach(() => {
   vi.mocked(uploadHostFileToTerminal).mockResolvedValue("/workspace/api/dropped.txt");
   dragDrop.handler = null;
   ptyOutput.listeners.clear();
+  vi.mocked(openUrl).mockReset();
+  vi.mocked(openUrl).mockResolvedValue(undefined);
+  containerEnv.bridge = { enabled: false, active_ports: [], conflicts: [] };
+  containerEnv.detection = null;
+  // The Playwright probe is memoized across mounts (it is a container exec), so
+  // a case that changes the answer has to drop what an earlier one cached.
+  resetBrowserSupportCache();
+  useAppState.setState({ toasts: [] });
   document.body.innerHTML = "";
   useAppState.setState({ sessions: [] });
 });
@@ -559,6 +587,214 @@ describe("TerminalView — reaching the URL prompt without a mouse", () => {
   });
 });
 
+/**
+ * A container with Playwright *and* a browser in the cache — i.e. one where
+ * "In container" would actually open something.
+ */
+function usableDetection(
+  over: Partial<PlaywrightDetection> = {},
+): PlaywrightDetection {
+  return {
+    node_version: "v22.11.0",
+    playwright_version: "1.56.0",
+    playwright_path: "/workspace/node_modules/playwright",
+    playwright_cli: "/workspace/node_modules/playwright/cli.js",
+    has_bind: true,
+    cli_version: "1.56.0",
+    cli_entry: "/workspace/node_modules/@playwright/cli/index.js",
+    browsers: ["chromium-1200"],
+    chrome_channel: null,
+    chromium_executable: "/home/claude/.cache/ms-playwright/chromium-1200/chrome",
+    chromium_executable_exists: true,
+    script_playwright_version: "1.56.0",
+    script_chromium_executable: null,
+    script_chromium_executable_exists: false,
+    searched: [],
+    ...over,
+  };
+}
+
+const LIVE_BRIDGE: AuthBridgeStatus = {
+  enabled: true,
+  active_ports: [],
+  conflicts: [],
+};
+
+describe("chooseSignInTarget — which action leads for a sign-in link", () => {
+  // The rule this replaced was "container, always", justified by the callback
+  // listener living inside the container. Both halves of that justification
+  // stopped being true: the auth bridge mirrors that listener onto the host,
+  // and the container-side target is Playwright's pane, whose browsers are not
+  // in the image.
+  it("prefers the host browser whenever the bridge is live", () => {
+    expect(chooseSignInTarget(LIVE_BRIDGE, usableDetection())).toBe("host");
+  });
+
+  it("does not call a bridge live while it is holding a port conflict", () => {
+    // Enabled and unable to catch the callback anyway — the one state where
+    // "on" must not read as "will work".
+    const conflicted: AuthBridgeStatus = {
+      enabled: true,
+      active_ports: [],
+      conflicts: [{ port: 54545, reason: "already in use on the host" }],
+    };
+    expect(chooseSignInTarget(conflicted, usableDetection())).toBe("container");
+  });
+
+  it("does not wait for a bridged port before trusting an enabled bridge", () => {
+    // There is nothing to bridge until the CLI binds its listener, and that
+    // races the URL reaching the transcript. Requiring a port would make the
+    // default flip between two identical sign-ins.
+    expect(chooseSignInTarget(LIVE_BRIDGE, null)).toBe("host");
+  });
+
+  it("falls to the container only when it has a browser to open", () => {
+    const off: AuthBridgeStatus = { enabled: false, active_ports: [], conflicts: [] };
+    expect(chooseSignInTarget(off, usableDetection())).toBe("container");
+    expect(chooseSignInTarget(off, null)).toBe("host");
+    // Packages installed, cache empty — the fresh-project state, and the one
+    // that used to be the silent default.
+    expect(
+      chooseSignInTarget(
+        off,
+        usableDetection({ browsers: [], chromium_executable_exists: false }),
+      ),
+    ).toBe("host");
+    // Playwright too old to bind: the pane cannot show it either.
+    expect(chooseSignInTarget(off, usableDetection({ has_bind: false }))).toBe("host");
+  });
+
+  it("answers host when nothing is known at all", () => {
+    expect(chooseSignInTarget(null, null)).toBe("host");
+  });
+});
+
+describe("TerminalView — the sign-in default follows the project", () => {
+  const SIGN_IN =
+    "https://claude.ai/oauth/authorize?code=true&client_id=abc&response_type=code";
+
+  function relaySequence(url: string): number[] {
+    return Array.from(
+      new TextEncoder().encode(`\x1b]7777;open;${btoa(url)}\x07`),
+    );
+  }
+
+  async function mountWithPrompt() {
+    const view = mountSession("claude");
+    await act(async () => {});
+    const emit = ptyOutput.listeners.get("terminal-output-s1");
+    if (!emit) throw new Error("no terminal-output listener registered");
+    await act(async () => {
+      emit({ payload: relaySequence(SIGN_IN) });
+      await new Promise((r) => setTimeout(r, 0));
+      await new Promise((r) => setTimeout(r, 0));
+    });
+    return view;
+  }
+
+  function primaryLabel(): string | null {
+    return document.querySelector<HTMLElement>(
+      '[data-url-toast-primary="true"]',
+    )?.textContent ?? null;
+  }
+
+  function actionOrder(): (string | null)[] {
+    return Array.from(document.querySelectorAll("button"))
+      .map((b) => b.textContent)
+      .filter((t) => t === "Open" || t === "In container");
+  }
+
+  it("leads with the host browser when the auth bridge is on", async () => {
+    containerEnv.bridge = LIVE_BRIDGE;
+    containerEnv.detection = usableDetection();
+    await mountWithPrompt();
+    expect(primaryLabel()).toBe("Open");
+    // Both are still offered — this changes which leads, never which exist.
+    expect(actionOrder()).toEqual(["Open", "In container"]);
+  });
+
+  it("leads with the container when the bridge is off and a browser is there", async () => {
+    containerEnv.detection = usableDetection();
+    await mountWithPrompt();
+    expect(primaryLabel()).toBe("In container");
+    expect(actionOrder()).toEqual(["In container", "Open"]);
+  });
+
+  it("leads with the host on a fresh project, where neither is set up", async () => {
+    // Playwright is deliberately not baked into the image, so this is what a
+    // project looks like until someone presses install — and pointing the
+    // default at it failed on every platform, silently.
+    await mountWithPrompt();
+    expect(primaryLabel()).toBe("Open");
+  });
+});
+
+describe("TerminalView — a host open that fails says so", () => {
+  const URL = "https://github.com/login/device?code=ABCD-EFGH";
+
+  function relaySequence(url: string): number[] {
+    return Array.from(
+      new TextEncoder().encode(`\x1b]7777;open;${btoa(url)}\x07`),
+    );
+  }
+
+  async function mountWithPrompt() {
+    const view = mountSession("claude");
+    await act(async () => {});
+    const emit = ptyOutput.listeners.get("terminal-output-s1");
+    if (!emit) throw new Error("no terminal-output listener registered");
+    await act(async () => {
+      emit({ payload: relaySequence(URL) });
+      await new Promise((r) => setTimeout(r, 0));
+      await new Promise((r) => setTimeout(r, 0));
+    });
+    return view;
+  }
+
+  function openButton(): HTMLElement {
+    const el = Array.from(document.querySelectorAll("button")).find(
+      (b) => b.textContent === "Open",
+    );
+    if (!el) throw new Error("Open button not found");
+    return el as HTMLElement;
+  }
+
+  it("pushes a toast instead of a console line nobody reads", async () => {
+    vi.mocked(openUrl).mockRejectedValueOnce(new Error("no opener"));
+    await mountWithPrompt();
+    await act(async () => {
+      fireEvent.click(openButton());
+      await Promise.resolve();
+    });
+    const toasts = useAppState.getState().toasts;
+    expect(toasts).toHaveLength(1);
+    expect(toasts[0].kind).toBe("error");
+    expect(toasts[0].detail).toContain("no opener");
+  });
+
+  it("keeps the prompt on screen, so the other route is still one click away", async () => {
+    // Dismissing first is what this replaced: the toast vanished, nothing
+    // opened, and the URL only existed in the container's transcript.
+    vi.mocked(openUrl).mockRejectedValueOnce(new Error("no opener"));
+    await mountWithPrompt();
+    await act(async () => {
+      fireEvent.click(openButton());
+      await Promise.resolve();
+    });
+    expect(document.querySelector(URL_TOAST_SELECTOR)).not.toBeNull();
+  });
+
+  it("dismisses the prompt once the handoff actually succeeded", async () => {
+    await mountWithPrompt();
+    await act(async () => {
+      fireEvent.click(openButton());
+      await Promise.resolve();
+    });
+    expect(openUrl).toHaveBeenCalledWith(URL);
+    expect(document.querySelector(URL_TOAST_SELECTOR)).toBeNull();
+  });
+});
+
 describe("TerminalView — focus on request", () => {
   /** Mount, then deliberately give focus away, so what the assertions below
    *  observe is the *request* taking effect and never the focus `active`

app/src/components/terminal/TerminalView.tsx

@@ -23,6 +23,7 @@ import {
   sanitizeRelayUrl,
 } from "../../lib/urlRelay";
 import { classifyDrop, DROP_BLOCKED_TOAST } from "../../lib/dropTarget";
+import { useSignInOpenTarget } from "../../hooks/useSignInOpenTarget";
 import UrlToast, {
   URL_TOAST_PRIMARY_SELECTOR,
   URL_TOAST_SELECTOR,
@@ -409,7 +410,18 @@ export default function TerminalView({ sessionId, active }: Props) {
         console.warn("Refusing to open a link that failed validation");
         return;
       }
-      openUrl(safe).catch((e) => console.error("Failed to open URL:", e));
+      // Same failure reporting as the toast's Open button — see the long note
+      // on `handleOpenUrl`, including what this catch does *not* catch on
+      // Linux. A click that appears to do nothing is the complaint either way.
+      openUrl(safe).catch((e) =>
+        useAppState.getState().pushToast({
+          kind: "error",
+          message: "Could not open that link in your browser",
+          detail: String(e),
+          // A dead opener fails for every link in the buffer. One card.
+          dedupeKey: "host-open-failed",
+        }),
+      );
     }, { urlRegex });
     term.loadAddon(webLinksAddon);
 
@@ -786,20 +798,58 @@ export default function TerminalView({ sessionId, active }: Props) {
     return () => clearTimeout(timer);
   }, [imagePasteMsg]);
 
+  /**
+   * Hand the prompted URL to the host's browser.
+   *
+   * Two things here are ordering, not decoration:
+   *
+   *  - **The toast is dismissed on success only.** It used to go first, so a
+   *    failed open left the user with an empty screen and no way back to a URL
+   *    that only exists in the container's transcript. Now a failure keeps the
+   *    prompt exactly where it was, which also leaves "In container" one click
+   *    away — the fallback this failure is the argument for.
+   *  - **The failure is a toast, not a `console.error`.** Same `pushToast` the
+   *    container-browser branch below uses, because from the user's side the
+   *    two actions fail identically: nothing happens.
+   *
+   * What this does *not* cover, and must not be described as covering: on Linux
+   * `xdg-open` routinely exits 0 having done nothing useful, so the most common
+   * Linux failure resolves this promise and reports success. Stripping the
+   * leaked AppImage environment before the browser is spawned is what addresses
+   * that; this is the complement that catches everything which does report.
+   */
   const handleOpenUrl = useCallback(() => {
     if (!urlPrompt) return;
     // Validated again at the sink. `promptUrl` is the only writer and already
     // sanitizes, so this can only fail if that invariant is broken — which is
     // precisely when it matters that the last thing before `openUrl` checks.
     const safe = sanitizeRelayUrl(urlPrompt.url);
-    dismissUrlPrompt();
     if (!safe) {
       console.warn("Refusing to open a URL that failed validation");
+      dismissUrlPrompt();
       return;
     }
-    openUrl(safe).catch((e) => console.error("Failed to open URL:", e));
+    openUrl(safe)
+      .then(() => dismissUrlPrompt())
+      .catch((e) =>
+        useAppState.getState().pushToast({
+          kind: "error",
+          message: "Could not open it in your browser",
+          detail: String(e),
+          dedupeKey: "host-open-failed",
+        }),
+      );
   }, [urlPrompt, dismissUrlPrompt]);
 
+  /**
+   * Which action leads when the prompt is holding an Anthropic sign-in link.
+   *
+   * Resolved per project, not per URL — see `useSignInOpenTarget`. The toast
+   * offers both regardless; this is only which one is filled in and reachable
+   * with {@link URL_TOAST_SHORTCUT}.
+   */
+  const signInDefault = useSignInOpenTarget(projectId);
+
   /**
    * Open the prompted URL in the container's own browser instead of the host's.
    *
@@ -896,6 +946,7 @@ export default function TerminalView({ sessionId, active }: Props) {
           label={urlPrompt.label}
           onOpen={handleOpenUrl}
           onOpenInContainer={handleOpenUrlInContainer}
+          signInDefault={signInDefault}
           onDismiss={dismissUrlPrompt}
         />
       )}

app/src/components/terminal/UrlToast.test.tsx

@@ -105,6 +105,7 @@ describe("UrlToast", () => {
           url={SIGN_IN}
           onOpen={noop}
           onOpenInContainer={noop}
+          signInDefault="container"
           onDismiss={noop}
         />,
       );
@@ -150,6 +151,7 @@ describe("UrlToast", () => {
           url={SIGN_IN}
           onOpen={noop}
           onOpenInContainer={noop}
+          signInDefault="container"
           onDismiss={noop}
         />,
       );
@@ -166,10 +168,11 @@ describe("UrlToast", () => {
 
   describe("Anthropic sign-in links", () => {
     // The callback listener a `claude login` is waiting on is *inside* the
-    // container. Sending the user to their host browser completes the sign-in
+    // container, so a sign-in is the one case where the host browser may be the
-    // and then posts the result where nothing is listening, and the terminal
+    // wrong lead. Whether it actually is depends on the project — a live auth
-    // hangs to its timeout — so for these, and only these, the container-side
+    // bridge carries the callback back, and the container-side alternative is
-    // browser leads.
+    // not installed on a fresh project — so the owner decides and passes
+    // `signInDefault`. This component only renders the decision.
     const SIGN_IN =
       "https://claude.ai/oauth/authorize?code=true&client_id=abc&response_type=code";
 
@@ -180,12 +183,13 @@ describe("UrlToast", () => {
         .filter((t) => t === "Open" || t === "In container");
     }
 
-    it("puts the container browser first", () => {
+    it("puts the container browser first when the caller asks for it", () => {
       render(
         <UrlToast
           url={SIGN_IN}
           onOpen={noop}
           onOpenInContainer={noop}
+          signInDefault="container"
           onDismiss={noop}
         />,
       );
@@ -195,6 +199,42 @@ describe("UrlToast", () => {
       );
     });
 
+    it("leads with the host when the caller says so, without hiding the other", () => {
+      // A live auth bridge, or a container with no browser installed. The pair
+      // is unchanged; only the order and which one is filled.
+      render(
+        <UrlToast
+          url={SIGN_IN}
+          onOpen={noop}
+          onOpenInContainer={noop}
+          signInDefault="host"
+          onDismiss={noop}
+        />,
+      );
+      expect(actions()).toEqual(["Open", "In container"]);
+      expect(
+        document.querySelector(URL_TOAST_PRIMARY_SELECTOR),
+      ).toHaveTextContent("Open");
+      // Still recognised as a sign-in, so the explanation stays.
+      expect(screen.getByTestId("url-toast-signin-hint")).toHaveTextContent(
+        /auth bridge/i,
+      );
+    });
+
+    it("defaults to the host when the caller passes nothing", () => {
+      // The safe fallback: the answer more likely to work, and the one that
+      // reports its own failure.
+      render(
+        <UrlToast
+          url={SIGN_IN}
+          onOpen={noop}
+          onOpenInContainer={noop}
+          onDismiss={noop}
+        />,
+      );
+      expect(actions()).toEqual(["Open", "In container"]);
+    });
+
     it("keeps the host browser available as a fallback", () => {
       const onOpen = vi.fn();
       render(
@@ -202,6 +242,7 @@ describe("UrlToast", () => {
           url={SIGN_IN}
           onOpen={onOpen}
           onOpenInContainer={noop}
+          signInDefault="container"
           onDismiss={noop}
         />,
       );
@@ -211,12 +252,14 @@ describe("UrlToast", () => {
 
     it("leaves an ordinary URL alone", () => {
       // A `gh auth login` device code, a docs page, a preview build — the host
-      // browser is the right answer for all of them and stays the default.
+      // browser is the right answer for all of them and stays the default,
+      // whatever the project's sign-in preference happens to be.
       render(
         <UrlToast
           url="https://github.com/login/device?code=ABCD-EFGH"
           onOpen={noop}
           onOpenInContainer={noop}
+          signInDefault="container"
           onDismiss={noop}
         />,
       );
@@ -232,6 +275,7 @@ describe("UrlToast", () => {
           url="https://claude.ai.evil.tld/oauth/authorize?x=1"
           onOpen={noop}
           onOpenInContainer={noop}
+          signInDefault="container"
           onDismiss={noop}
         />,
       );

app/src/components/terminal/UrlToast.tsx

@@ -37,6 +37,18 @@ interface Props {
   /** Open it in the container's own browser instead of the host's. Omitted when
    *  the project has no browser to open it in. */
   onOpenInContainer?: () => void;
+  /**
+   * Which action leads for a *sign-in* link (see the note below). Nothing else
+   * in the toast moves: both buttons are offered either way, in either order.
+   *
+   * This component does not work it out, because the answer depends on the
+   * project's auth bridge and on what is installed inside its container —
+   * neither of which a presentational component should be reaching for.
+   * `hooks/useSignInOpenTarget.ts` owns the rule. `"host"` is the default here
+   * for the same reason it is the fallback there: it is the answer that is more
+   * likely to work, and the one that reports its own failure.
+   */
+  signInDefault?: "host" | "container";
   onDismiss: () => void;
 }
 
@@ -57,17 +69,20 @@ interface Props {
  * text swaps with no animation, and a user reading URL A can click Open on URL
  * B that arrived a second later.
  *
- * ## Anthropic sign-in links default to the container's browser
+ * ## Anthropic sign-in links get their default from the caller
  *
  * For an ordinary URL the host browser is the right answer and stays the
- * default. For a sign-in it is the *wrong* one: the callback listener the CLI
+ * default, unconditionally. A sign-in is the one case where it might not be:
- * is waiting on is inside the container, so a host browser completes the sign-in
+ * the callback listener the CLI is waiting on is inside the container, so a
- * and then posts the result somewhere nothing is listening, and the terminal
+ * host browser can complete the sign-in and then post the result where nothing
- * hangs until it times out. Making the host button primary there was quietly
+ * is listening, leaving the terminal to hang to its timeout.
- * steering every user into that. The container-side browser closes the loop
+ *
- * with no host round trip and no auth bridge, so it leads — and the host button
+ * *Can*, not *does* — which is why this is no longer decided from the URL. The
- * stays, because a user who has the auth bridge on, or who wants their existing
+ * auth bridge mirrors that container listener onto the same host port, and the
- * browser session, still needs it.
+ * container-side alternative is Playwright's dashboard pane, which a fresh
+ * project has not installed. Both of those are project facts, so the owner
+ * passes {@link Props.signInDefault} and this only renders it: the leading
+ * button is filled and comes first, the other keeps its place beside it.
  *
  * ## Reachable without a mouse, and it does not take focus to manage it
  *
@@ -96,6 +111,7 @@ export default function UrlToast({
   label = "Long URL detected",
   onOpen,
   onOpenInContainer,
+  signInDefault = "host",
   onDismiss,
 }: Props) {
   const origin = urlOrigin(url);
@@ -103,18 +119,22 @@ export default function UrlToast({
   // Only when there is somewhere to send it: without `onOpenInContainer` the
   // host button is the only action there is, so it stays primary.
   const signIn = !!onOpenInContainer && isAnthropicSignInUrl(url);
+  // A sign-in link the caller has decided is better completed inside the
+  // container. Everything below keys off this rather than off `signIn`, so the
+  // two orderings differ only in which of the pair leads.
+  const containerLeads = signIn && signInDefault === "container";
 
   // `Button` already owns the filled/outlined variants — including the rule
   // that filled uses `--accent-emphasis` and never `--accent`, which is the
   // foreground/link accent and fails WCAG AA behind white text.
   const hostButton = (
     <Button
-      variant={signIn ? "secondary" : "primary"}
+      variant={containerLeads ? "secondary" : "primary"}
-      data-url-toast-primary={signIn ? undefined : "true"}
+      data-url-toast-primary={containerLeads ? undefined : "true"}
       onClick={onOpen}
       className="flex-shrink-0"
       title={
-        signIn
+        containerLeads
           ? "Open in your own browser instead — the callback then has to reach the container by some other route"
           : undefined
       }
@@ -128,8 +148,8 @@ export default function UrlToast({
     // the container's own loopback, which is where the tool waiting for it is
     // listening — no host round trip, no auth bridge.
     <Button
-      variant={signIn ? "primary" : "secondary"}
+      variant={containerLeads ? "primary" : "secondary"}
-      data-url-toast-primary={signIn ? "true" : undefined}
+      data-url-toast-primary={containerLeads ? "true" : undefined}
       onClick={onOpenInContainer}
       className="flex-shrink-0"
       title="Open in a browser inside the container, and watch it in the Browser tab"
@@ -235,14 +255,14 @@ export default function UrlToast({
               lineHeight: 1.35,
             }}
           >
-            Sign-in link — the callback listener is inside the container.
+            {containerLeads
-            Opening it there closes the loop; the host browser needs the auth
+              ? "Sign-in link — the callback listener is inside the container. Opening it there closes the loop; the host browser needs the auth bridge."
-            bridge.
+              : "Sign-in link — the callback listener is inside the container. The auth bridge is what carries the callback back to it from your own browser."}
           </div>
         )}
       </div>
 
-      {signIn ? (
+      {containerLeads ? (
         <>
           {containerButton}
           {hostButton}

app/src/hooks/useSignInOpenTarget.ts

@@ -0,0 +1,176 @@
+import { useEffect, useState } from "react";
+import { listen } from "@tauri-apps/api/event";
+import {
+  checkBrowserViewSupport,
+  getAuthBridgeStatus,
+} from "../lib/tauri-commands";
+import { canOpenPageInContainerBrowser } from "../lib/browserViewSupport";
+import type {
+  AuthBridgeChangedEvent,
+  AuthBridgeStatus,
+  PlaywrightDetection,
+} from "../lib/types";
+
+/** Emitted by `auth_bridge/mod.rs` whenever the port or conflict set changes. */
+const AUTH_BRIDGE_EVENT = "auth-bridge-changed";
+
+/** Which of the URL toast's two buttons should lead for a sign-in link. */
+export type SignInOpenTarget = "host" | "container";
+
+/**
+ * Whether the auth bridge can be relied on to catch a callback for this
+ * project.
+ *
+ * Deliberately **not** gated on `active_ports` being non-empty. There is only
+ * something to bridge once the CLI has bound its callback listener, and the
+ * order in which that happens against the URL landing in the transcript is not
+ * ours to control — requiring a port here would make the answer depend on a
+ * race and flip the default button between two otherwise identical sign-ins.
+ * `enabled` is the durable fact: the poller is watching, and it will mirror the
+ * port the moment it appears.
+ *
+ * A conflict is the exception, because it is the one state where the bridge is
+ * on and nevertheless *cannot* catch the callback — the host port it needed was
+ * already taken. That is precisely when the container-side browser is the
+ * better default, so it must not read as live.
+ */
+export function authBridgeIsLive(status: AuthBridgeStatus | null): boolean {
+  if (!status || !status.enabled) return false;
+  return status.conflicts.length === 0;
+}
+
+/**
+ * The rule, as a pure function of the two things it depends on.
+ *
+ * Both fallbacks land on the host, for different reasons:
+ *
+ *  - With the bridge live, the host browser is strictly better — it is the
+ *    user's own signed-in profile, and the callback still reaches the container.
+ *  - With neither available, the host is the *more likely to work* of two
+ *    imperfect answers, and it is the one that reports its own failure (see
+ *    `handleOpenUrl` in `TerminalView`). The container-side target is
+ *    Playwright's dashboard pane, and Playwright's browsers are not baked into
+ *    the image, so on a fresh project pointing there fails on every platform
+ *    after a several-second wait.
+ *
+ * Whichever way it goes, both buttons stay in the toast. This chooses which one
+ * leads, never which ones exist.
+ */
+export function chooseSignInTarget(
+  bridge: AuthBridgeStatus | null,
+  detection: PlaywrightDetection | null,
+): SignInOpenTarget {
+  if (authBridgeIsLive(bridge)) return "host";
+  if (canOpenPageInContainerBrowser(detection)) return "container";
+  return "host";
+}
+
+/**
+ * How long a Playwright probe is reused for.
+ *
+ * `check_browser_view_support` is a `docker exec` running a Node probe, and
+ * every terminal tab of a project would otherwise run its own on mount. Five
+ * minutes is long enough that opening a handful of tabs costs one exec, and
+ * short enough that pressing "Set up Playwright" in the Browser tab is
+ * reflected in the default before the user has finished reading the result.
+ */
+const DETECTION_TTL_MS = 5 * 60_000;
+
+const detectionCache = new Map<
+  string,
+  { at: number; probe: Promise<PlaywrightDetection | null> }
+>();
+
+/** The shared, rate-limited probe. Never rejects — "didn't answer" is `null`. */
+function probeBrowserSupport(projectId: string): Promise<PlaywrightDetection | null> {
+  const hit = detectionCache.get(projectId);
+  if (hit && Date.now() - hit.at < DETECTION_TTL_MS) return hit.probe;
+  const probe = checkBrowserViewSupport(projectId).catch(() => {
+    // A failure is usually a stopped container, which is a state the user
+    // leaves — so it is not worth remembering for five minutes.
+    detectionCache.delete(projectId);
+    return null;
+  });
+  detectionCache.set(projectId, { at: Date.now(), probe });
+  return probe;
+}
+
+/** Test seam: drops the memoized probes so a case starts from nothing. */
+export function resetBrowserSupportCache(): void {
+  detectionCache.clear();
+}
+
+/**
+ * Resolve the default action for Anthropic sign-in links in this project.
+ *
+ * Resolved at mount rather than when a URL arrives, on purpose: the toast has
+ * two buttons side by side, and a default that settles a second after the
+ * toast appears moves them under a mouse that is already travelling.
+ *
+ * The expensive half is only paid when it can change the answer. The bridge
+ * status is host-side and cheap; the Playwright probe is a container exec, and
+ * a live bridge decides the question before it is ever asked — which, with the
+ * bridge now on by default, is the ordinary case.
+ */
+export function useSignInOpenTarget(projectId: string | undefined): SignInOpenTarget {
+  const [target, setTarget] = useState<SignInOpenTarget>("host");
+
+  useEffect(() => {
+    if (!projectId) {
+      setTarget("host");
+      return;
+    }
+
+    let cancelled = false;
+    let bridge: AuthBridgeStatus | null = null;
+    let detection: PlaywrightDetection | null = null;
+
+    const settle = () => {
+      if (!cancelled) setTarget(chooseSignInTarget(bridge, detection));
+    };
+
+    const consider = (next: AuthBridgeStatus) => {
+      bridge = next;
+      settle();
+      // Only now is the container's side of it worth an exec.
+      if (authBridgeIsLive(bridge)) return;
+      probeBrowserSupport(projectId).then((d) => {
+        if (cancelled) return;
+        detection = d;
+        settle();
+      });
+    };
+
+    getAuthBridgeStatus(projectId)
+      .then((s) => {
+        if (!cancelled) consider(s);
+      })
+      // Nothing to say to the user here: this only picks which button is
+      // filled in, and the fallback is the one that reports its own failures.
+      .catch(() => {
+        if (!cancelled) consider({ enabled: false, active_ports: [], conflicts: [] });
+      });
+
+    // The switch can be flipped *while a login is hanging* — that is the whole
+    // reason `set_auth_bridge_enabled` exists outside the Config tab's save —
+    // so the default has to follow it rather than reflect whatever was true
+    // when this terminal was opened.
+    let unlisten: (() => void) | undefined;
+    listen<AuthBridgeChangedEvent>(AUTH_BRIDGE_EVENT, (event) => {
+      if (event.payload.project_id !== projectId) return;
+      consider(event.payload.status);
+    })
+      .then((un) => {
+        if (cancelled) un();
+        else unlisten = un;
+      })
+      .catch(() => {});
+
+    return () => {
+      cancelled = true;
+      unlisten?.();
+    };
+  }, [projectId]);
+
+  return target;
+}

app/src/lib/browserViewSupport.ts

@@ -0,0 +1,53 @@
+/**
+ * What a container has to have before anything can be opened *inside* it.
+ *
+ * The Browser tab asks this to decide what to offer; the terminal's URL toast
+ * asks it to decide which of its two buttons should lead. Both need the same
+ * answer, so the predicates live here rather than beside either caller — the
+ * failure this avoids is the toast steering a user at a container-side browser
+ * that the Browser tab is, on the very same screen, offering to install.
+ *
+ * The important thing to know about `PlaywrightDetection` is that browsers are
+ * deliberately **not** baked into the image: the libraries they link against
+ * are, the binaries are a user-pressed install. So "Playwright is present" and
+ * "a page can actually be opened" are two different questions, and a fresh
+ * project answers yes to neither.
+ */
+
+import type { PlaywrightDetection } from "./types";
+
+/**
+ * Mirrors Rust `PlaywrightDetection::is_usable` — the packages the live
+ * dashboard needs. Says nothing about whether a browser exists to show in it.
+ */
+export function isBrowserViewUsable(d: PlaywrightDetection | null): boolean {
+  return d !== null && d.playwright_version !== null && d.has_bind && d.cli_entry !== null;
+}
+
+/**
+ * Whether `openPageInContainerBrowser` has a browser to launch.
+ *
+ * Stricter than {@link isBrowserViewUsable} on purpose: the packages can be
+ * installed with `~/.cache/ms-playwright` still empty, which is exactly the
+ * state a `playwright install` step exists to leave behind, and launching into
+ * it fails several seconds after the click.
+ *
+ * Unknown reads as "no". A probe that could not run (stopped container, an
+ * image predating these fields) leaves the executable fields absent, and the
+ * caller's fallback — the host browser — is the one that at least reports its
+ * own failure. Over-refusing costs a user one extra click on a button that is
+ * still right there; over-accepting costs them a sign-in that goes nowhere.
+ */
+export function canOpenPageInContainerBrowser(d: PlaywrightDetection | null): boolean {
+  if (!isBrowserViewUsable(d) || !d) return false;
+  // The viewer's own Chromium, confirmed on disk by the probe.
+  if (d.chromium_executable_exists) return true;
+  // Google Chrome is an apt package, so it is never in `browsers` and has no
+  // revision to skew against.
+  if (d.chrome_channel !== null) return true;
+  // `== null`, not `=== null`: a probe from a container predating the
+  // executable fields omits them entirely, and `undefined` there means "didn't
+  // answer", not "missing". In that case a non-empty bundle list is the only
+  // evidence available, and it is better than nothing.
+  return d.chromium_executable == null && d.browsers.length > 0;
+}

app/src/lib/urlRelay.test.ts

@@ -4,6 +4,7 @@ import {
   MAX_RELAY_URL_LENGTH,
   RelayRateLimiter,
   URL_RELAY_OSC,
+  isAnthropicSignInUrl,
   parseUrlRelayOsc,
   sanitizeRelayUrl,
   urlOrigin,
@@ -321,3 +322,53 @@ describe("RelayRateLimiter", () => {
     expect(rl.allow("https://c.example/", 10_200)).toBe(true);
   });
 });
+
+describe("isAnthropicSignInUrl", () => {
+  // Classification only. Where a sign-in link should be opened is decided by
+  // `hooks/useSignInOpenTarget.ts`, from facts about the project — this answers
+  // the narrower question of whether it is a sign-in link at all, and it does
+  // so through the same allowlist the sign-in flow itself uses.
+  it("recognises the links `claude setup-token` and `claude login` print", () => {
+    expect(
+      isAnthropicSignInUrl(
+        "https://claude.ai/oauth/authorize?code=true&client_id=abc",
+      ),
+    ).toBe(true);
+    expect(
+      isAnthropicSignInUrl("https://platform.claude.com/oauth/code/callback?x=1"),
+    ).toBe(true);
+    expect(isAnthropicSignInUrl("https://console.anthropic.com/login?x=1")).toBe(
+      true,
+    );
+  });
+
+  it("is not fooled by a host that merely contains an allowed domain", () => {
+    // The thing the allowlist exists for: `claude.ai.evil.tld` ends with
+    // neither `claude.ai` nor `.claude.ai`.
+    expect(isAnthropicSignInUrl("https://claude.ai.evil.tld/oauth/authorize")).toBe(
+      false,
+    );
+    expect(isAnthropicSignInUrl("https://notclaude.ai/login")).toBe(false);
+  });
+
+  it("holds the full validator, not just the host test", () => {
+    // It runs `sanitizeRelayUrl`, so everything that cannot be opened at all
+    // is not a sign-in link either — no separate, weaker copy of the rules.
+    expect(isAnthropicSignInUrl("javascript:claude.ai/login")).toBe(false);
+    expect(isAnthropicSignInUrl("https://claude.ai@evil.tld/login")).toBe(false);
+    expect(isAnthropicSignInUrl("https://claude\nai/login")).toBe(false);
+  });
+
+  it("does not claim every allowlisted URL is a sign-in", () => {
+    expect(isAnthropicSignInUrl("https://claude.ai/chat/abc")).toBe(false);
+    expect(isAnthropicSignInUrl("https://www.anthropic.com/news")).toBe(false);
+  });
+
+  it("leaves an ordinary link alone, whatever it says in its path", () => {
+    // A `gh auth login` device code is the common one, and sending it to a
+    // container-side browser would be actively wrong.
+    expect(isAnthropicSignInUrl("https://github.com/login/device?code=A")).toBe(
+      false,
+    );
+  });
+});

app/src/lib/urlRelay.ts

@@ -182,11 +182,22 @@ export function extendsUrl(next: string, current: string): boolean {
 /**
  * Whether this is a URL that signs the user in to Anthropic.
  *
- * Used to decide *presentation*, not permission — the toast makes the
+ * Classification only. It answers "is this a sign-in link", never "where should
- * container-side browser the default action for these, because the OAuth
+ * it be opened" — that decision moved out to `hooks/useSignInOpenTarget.ts`,
- * callback listener is inside the container and the host has nothing to catch
+ * because it depends on things this module has no business knowing: whether the
- * it with. It is deliberately the same host allowlist the sign-in flow itself
+ * project's auth bridge is live, and whether a browser is actually installed in
- * uses, so the two cannot disagree about what a sign-in link is.
+ * the container. This function stays here because the *rule* it encodes is a
+ * URL rule, and it is deliberately the same host allowlist the sign-in flow
+ * itself uses, so the two cannot disagree about what a sign-in link is.
+ *
+ * It used to carry the default with it — container-side always, on the grounds
+ * that "the OAuth callback listener is inside the container and the host has
+ * nothing to catch it with". Both halves of that are now wrong. The host does
+ * have something to catch it with (the auth bridge mirrors the container's
+ * loopback listener onto the same host port), and the container-side target is
+ * not a general browser but Playwright's dashboard pane, whose browsers are
+ * deliberately not baked into the image — so on a fresh project the default
+ * pointed at something that was not installed, on every platform.
  */
 export function isAnthropicSignInUrl(url: string): boolean {
   const safe = sanitizeRelayUrl(url, { allowHosts: ANTHROPIC_SIGN_IN_HOSTS });