swarm-ui: stop a claude login whose dialog closed while it was starting

frontend/packages/swarm-ui/src/agent/claude-login/ClaudeLoginDialog.tsx

@@ -2,7 +2,8 @@
 // login minter. Opening it starts the login (`POST …/claude-login`), which
 // answers with the URL claude printed; the operator opens it and pastes the
 // code back (`POST …/claude-login/code`). Closing it while the code is
-// still awaited stops the login (`DELETE …/claude-login`).
+// still awaited stops the login (`DELETE …/claude-login`). Closing while the
+// start is still in flight stops it once the start answers.
 //
 // Mounted only while open, so each open is a fresh login.
 import { useEffect, useState } from "preact/hooks";
@@ -18,6 +19,7 @@ import {
   claudeLoginPath,
   leavesLoginRunning,
   pastedCode,
+  startOutlivedDialog,
   type LoginStep,
 } from "./ClaudeLoginSteps.js";
 import "./ClaudeLoginDialog.css";
@@ -42,6 +44,10 @@ export function ClaudeLoginDialog({
       try {
         const r = await fetch(claudeLoginPath(agent), { method: "POST" });
         const problem = await problemOf(r);
+        if (startOutlivedDialog(live, problem)) {
+          void fetch(claudeLoginPath(agent), { method: "DELETE" });
+          return;
+        }
         const next = afterStart(
           problem ? { problem } : ((await r.json()) as { url: string }),
         );

frontend/packages/swarm-ui/src/agent/claude-login/ClaudeLoginSteps.ts

@@ -34,6 +34,16 @@ export function leavesLoginRunning(s: LoginStep): boolean {
   return s.step === "code";
 }
 
+// Whether a start that answered after the dialog went away left a login
+// running: it did unless the start itself failed. The dialog stops it then,
+// since nothing is left to.
+export function startOutlivedDialog(
+  dialogLive: boolean,
+  problem: ProblemDetails | null,
+): boolean {
+  return !dialogLive && problem === null;
+}
+
 // What the code form may submit: the pasted code without surrounding
 // whitespace, or nothing.
 export function pastedCode(raw: string): string | null {

frontend/packages/swarm-ui/test/claude-login.test.mjs

@@ -9,6 +9,7 @@ import {
   claudeLoginPath,
   leavesLoginRunning,
   pastedCode,
+  startOutlivedDialog,
 } from "../src/agent/claude-login/ClaudeLoginSteps.ts";
 
 test("the routes name the agent, escaped", () => {
@@ -48,6 +49,12 @@ test("only a login waiting for its code is stopped on close", () => {
   assert.equal(leavesLoginRunning({ step: "stored" }), false);
 });
 
+test("a start that answers after the dialog closed is stopped, unless it failed", () => {
+  assert.equal(startOutlivedDialog(false, null), true);
+  assert.equal(startOutlivedDialog(true, null), false);
+  assert.equal(startOutlivedDialog(false, { detail: "no minter" }), false);
+});
+
 test("a pasted code is trimmed, and a blank one is nothing", () => {
   assert.equal(pastedCode("  abc-def \n"), "abc-def");
   assert.equal(pastedCode(" \n "), null);