fix: route sign-in links by what can actually catch the callback

`isAnthropicSignInUrl` made the container the default action for every
Anthropic sign-in link, justified by "the host has nothing to catch it
with". That was wrong in both directions. The host does have something --
the auth bridge -- and the container side is not a general browser at all
but Playwright's dashboard, whose packages and chromium are deliberately
not baked into the image. So the default pointed at the one path that is
uninstalled on a fresh project, on every platform, while the path that
works sat behind a switch.

The decision now lives in `useSignInOpenTarget`: a live auth bridge picks
the host, otherwise a container that can actually launch a browser picks
the container, otherwise the host. It resolves at mount rather than when a
URL arrives, so the buttons do not swap under a moving mouse, and it
re-decides on `auth-bridge-changed` so flipping the switch during a
hanging login takes effect. A bridge with port conflicts reads as not
live; an empty `active_ports` does not, since there is nothing to bridge
until the CLI binds its listener and that races the URL.

Both buttons still render either way -- this changes which one leads.
`sanitizeRelayUrl` is byte-for-byte unchanged, so the embedded copy in
web_terminal/terminal.html needs no matching edit.

The host "Open" path also failed silently: `dismissUrlPrompt()` ran before
`openUrl`, so the toast vanished and a rejected promise reached only the
devtools console. Dismissal now happens on success only, leaving "In
container" one click away after a failure, and the error surfaces through
the same toast the container path already used. On Linux this catch will
not fire for the common case -- `xdg-open` routinely exits 0 having done
nothing -- so it complements the AppImage environment fix rather than
replacing it.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

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
-    // and then posts the result where nothing is listening, and the terminal
-    // hangs to its timeout — so for these, and only these, the container-side
-    // browser leads.
+    // container, so a sign-in is the one case where the host browser may be the
+    // wrong lead. Whether it actually is depends on the project — a live auth
+    // bridge carries the callback back, and the container-side alternative is
+    // 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
- * is waiting on is inside the container, so a host browser completes the sign-in
- * and then posts the result somewhere nothing is listening, and the terminal
- * hangs until it times out. Making the host button primary there was quietly
- * 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
- * stays, because a user who has the auth bridge on, or who wants their existing
- * browser session, still needs it.
+ * default, unconditionally. A sign-in is the one case where it might not be:
+ * the callback listener the CLI is waiting on is inside the container, so a
+ * host browser can complete the sign-in and then post the result where nothing
+ * is listening, leaving the terminal to hang to its timeout.
+ *
+ * *Can*, not *does* — which is why this is no longer decided from the URL. The
+ * auth bridge mirrors that container listener onto the same host port, and the
+ * 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"}
-      data-url-toast-primary={signIn ? undefined : "true"}
+      variant={containerLeads ? "secondary" : "primary"}
+      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"}
-      data-url-toast-primary={signIn ? "true" : undefined}
+      variant={containerLeads ? "primary" : "secondary"}
+      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.
-            Opening it there closes the loop; the host browser needs the auth
-            bridge.
+            {containerLeads
+              ? "Sign-in link — the callback listener is inside the container. Opening it there closes the loop; the host browser needs the auth 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}