Fix the shared Claude auth flow: whole sign-in URL, recoverable rejected code

Two compounding bugs made `claude setup-token` unusable, both measured against
2.1.226 under a pty rather than reasoned about.

**The sign-in URL was truncated.** The CLI emits it as an OSC 8 hyperlink and
slices the *visible* text of that hyperlink to the terminal width: a 346
character URL arrives at 80 columns as five separate hyperlink emissions, each
carrying the whole URL in its parameter and 80 characters of it on screen. The
transcript scraper picked up the first slice — a URL that parses, points at
claude.com, and cannot authorise anything. The ANSI stripper now surfaces the
OSC 8 target and `claude-token-link` carries it to the UI, which prefers it over
the scraped text. It still goes through `sanitizeRelayUrl` with the
ANTHROPIC_SIGN_IN_HOSTS allowlist before display and again before `openUrl` — an
OSC 8 parameter is never rendered, which makes it the easier place to hide a
hostile host, not a trusted one. The wrapped-display fallback is kept for CLI
versions that print a bare URL.

**A rejected code hung the flow.** On a bad paste the CLI prints `OAuth error:
Invalid code…` / `Press Enter to retry.` and blocks on stdin instead of exiting;
nothing recognised that, so the exec sat until the 15-minute timeout with the UI
still saying "Finishing sign-in". Given the first bug handed the user a truncated
URL, an invalid code was the likely first outcome. The streamed output is now
scanned for that message, `claude-token-code-rejected` reopens the input with an
explanation, and the Enter is sent so the next code has a prompt to land in —
bounded by MAX_CODE_ATTEMPTS, after which the flow reports a failure. An
undeterminable exec exit status is logged rather than silently read as success.

**A wrapped token was rejected *and* leaked.** `stty cols` fails silently, and an
80-column fallback splits the ~103 character token across two lines: the parser
saw a too-short fragment and failed, while the redactor masked the first line —
which carries the `sk-ant-` marker — and printed the second, the tail of a live
credential, to the UI in clear. `scan_credential_body` now reassembles a run
across hard wraps and both the parser and the redactor use it, so they cannot
disagree about where a credential ends. A join only happens across a break at a
plausible terminal margin (>= 40 columns) and only for a run not already long
enough to be a whole credential — without that second guard a repainting TUI
welds one frame's token onto the next frame's first word. The length floor is
applied to the reassembled body, so a fragment is still never accepted.

Also: `stty cols` raised 200 -> 400 (the URL alone needs ~350), and `ESC ( B` is
handled as the three-byte charset designation it is — it prefixes every repaint
frame, and treating it as two bytes emitted a stray `B` that could glue itself
onto a token and make the parser refuse it.

`submit_claude_token_code`'s single-write behaviour is unchanged.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KSP2KNPhuWKQ4DL5TZEn3k

app/src/components/settings/ClaudeAuthModal.test.tsx

@@ -31,6 +31,22 @@ vi.mock("@tauri-apps/api/event", () => ({
   }),
 }));
 
+/** Every event the hook subscribes to, so the unmount test counts the right
+ *  number of teardowns instead of a magic number that drifts. */
+const EVENT_NAMES = [
+  "claude-token-progress",
+  "claude-token-output",
+  "claude-token-link",
+  "claude-token-code-rejected",
+];
+
+/** The sign-in URL at its real length (346 characters, measured against
+ *  Claude Code 2.1.226) and the 80-column slice of it that is all the visible
+ *  transcript ever contains. */
+const FULL_URL =
+  "https://claude.com/cai/oauth/authorize?code=true&client_id=9d1c250a-e61b-44d9-88ed-5944d1962f5e&response_type=code&redirect_uri=https%3A%2F%2Fplatform.claude.com%2Foauth%2Fcode%2Fcallback&scope=user%3Ainference&code_challenge=RUX5MlWvwld1dmpvF_aPIJQWMBmffuJt4dOdL13zWAg&code_challenge_method=S256&state=su-x9PgZzvkBd3-um6G1llLNDgxptyO6HERvvCSrTbg";
+const TRUNCATED_URL = FULL_URL.slice(0, 80);
+
 function emitOutput(chunk: string, projectId = "p1") {
   act(() => {
     handlers.get("claude-token-output")?.({
@@ -39,6 +55,26 @@ function emitOutput(chunk: string, projectId = "p1") {
   });
 }
 
+function emitLink(url: string, projectId = "p1") {
+  act(() => {
+    handlers.get("claude-token-link")?.({
+      payload: { project_id: projectId, url },
+    });
+  });
+}
+
+function emitCodeRejected(message: string, attemptsRemaining: number) {
+  act(() => {
+    handlers.get("claude-token-code-rejected")?.({
+      payload: {
+        project_id: "p1",
+        message,
+        attempts_remaining: attemptsRemaining,
+      },
+    });
+  });
+}
+
 function renderModal(
   overrides: { onClose?: () => void; onAuthenticated?: () => void } = {},
 ) {
@@ -200,6 +236,93 @@ describe("ClaudeAuthModal", () => {
     const { unmount } = renderModal();
     await flowStarted();
     unmount();
-    await waitFor(() => expect(unlisten).toHaveBeenCalledTimes(2));
+    await waitFor(() =>
+      expect(unlisten).toHaveBeenCalledTimes(EVENT_NAMES.length),
+    );
+  });
+
+  // ── The hyperlink target, not the wrapped display text ────────────────
+  //
+  // `claude setup-token` slices the *visible* text of its OSC 8 hyperlink to
+  // the terminal width, so the transcript holds five 80-character pieces of a
+  // 346-character URL. The backend lifts the whole thing out of the hyperlink
+  // parameter and sends it on `claude-token-link`.
+
+  it("prefers the hyperlink target over the wrapped copy in the transcript", async () => {
+    renderModal();
+    await flowStarted();
+
+    // What the transcript holds: the first slice only.
+    emitOutput(`Browser didn't open? Use the url below to sign in\n${TRUNCATED_URL}\n`);
+    // What the hyperlink parameter holds: all of it.
+    emitLink(FULL_URL);
+
+    const link = await screen.findByRole("link", { name: FULL_URL });
+    fireEvent.click(link);
+    await waitFor(() => expect(openUrl).toHaveBeenCalledWith(FULL_URL));
+    expect(openUrl).not.toHaveBeenCalledWith(TRUNCATED_URL);
+  });
+
+  it("refuses a hyperlink target that is not an Anthropic sign-in address", async () => {
+    renderModal();
+    await flowStarted();
+
+    emitLink("https://evil.tld/cai/oauth/authorize?code=true");
+
+    expect(screen.queryByRole("link")).not.toBeInTheDocument();
+    expect(openUrl).not.toHaveBeenCalled();
+  });
+
+  it("ignores a hyperlink belonging to a different project", async () => {
+    renderModal();
+    await flowStarted();
+
+    emitLink(FULL_URL, "p2");
+    expect(screen.queryByRole("link")).not.toBeInTheDocument();
+  });
+
+  // ── A refused code is recoverable, not a hang ─────────────────────────
+
+  it("reports a rejected code and lets another one be submitted", async () => {
+    renderModal();
+    await flowStarted();
+
+    const input = screen.getByLabelText("Authentication code");
+    fireEvent.change(input, { target: { value: "truncated" } });
+    fireEvent.click(screen.getByRole("button", { name: "Submit code" }));
+    await waitFor(() =>
+      expect(submitClaudeTokenCode).toHaveBeenCalledWith("truncated"),
+    );
+    // Before the rejection arrives the UI claims the sign-in is completing.
+    expect(screen.getByText("Finishing sign-in")).toBeInTheDocument();
+
+    emitCodeRejected(
+      "That code was rejected — `claude setup-token` reports the full code was not copied. Copy it again from the Anthropic page and submit it; 2 attempts left.",
+      2,
+    );
+
+    // Reported, not waited out — and the flow is still live.
+    await screen.findByText(/That code was rejected/);
+    expect(screen.getByText("Code rejected — try again")).toBeInTheDocument();
+    expect(screen.queryByText("Finishing sign-in")).not.toBeInTheDocument();
+    expect(screen.queryByTestId("claude-auth-error")).not.toBeInTheDocument();
+
+    // A second code goes through without restarting the whole flow.
+    fireEvent.change(input, { target: { value: "the-whole-code" } });
+    fireEvent.click(screen.getByRole("button", { name: "Submit code" }));
+    await waitFor(() =>
+      expect(submitClaudeTokenCode).toHaveBeenLastCalledWith("the-whole-code"),
+    );
+    expect(acquireClaudeToken).toHaveBeenCalledTimes(1);
+  });
+
+  it("ends with a reported failure when the retries run out", async () => {
+    acquireClaudeToken.mockRejectedValue(
+      "`claude setup-token` rejected the code 3 times, so the sign-in was abandoned. No token was stored.",
+    );
+    renderModal();
+
+    const banner = await screen.findByTestId("claude-auth-error");
+    expect(banner).toHaveTextContent(/rejected the code 3 times/);
   });
 });

app/src/components/settings/ClaudeAuthModal.tsx

@@ -27,6 +27,9 @@ interface Props {
 const PHASE_STATUS: Record<string, { tone: StatusTone; label: string }> = {
   waiting: { tone: "busy", label: "Waiting for sign-in" },
   finishing: { tone: "busy", label: "Finishing sign-in" },
+  // The CLI refused a code and is back at its prompt. Distinct from "failed":
+  // the flow is still live and another code will be accepted.
+  rejected: { tone: "error", label: "Code rejected — try again" },
   succeeded: { tone: "ok", label: "Token stored" },
   failed: { tone: "error", label: "Authentication failed" },
 };
@@ -88,7 +91,9 @@ export default function ClaudeAuthModal({
         ? PHASE_STATUS.failed
         : flow.codeSubmitted
           ? PHASE_STATUS.finishing
-          : PHASE_STATUS.waiting;
+          : flow.codeRejections > 0
+            ? PHASE_STATUS.rejected
+            : PHASE_STATUS.waiting;
 
   // Split for display only. `flow.signInUrl` has already passed the host
   // allowlist; this decides which half of it an ellipsis is allowed to eat.