agent: logout dialog now reflects #585's narrowed wipe (OAuth-only, session preserved)

After PR #585 (closes #584) narrowed the backend wipe to just
.credentials.json + mcp-needs-auth-cache.json (preserving
projects/<hash>/*.jsonl session history + everything else under
~/.claude/), the dialog wording I shipped in 9d58ec3 (which
described a full-dir wipe to satisfy argus's review against the
PRE-#585 backend) is now stale.

Updated to match what the backend actually does:

- title + slash desc + both confirm dialogs now say 'rotate OAuth
  credentials, --continue session history preserved'
- confirms explicitly name the two files deleted (.credentials.json,
  mcp-needs-auth-cache.json) so the operator knows exactly what's
  going + reassures that the conversation context survives
- 'agent picks up where it left off on the next turn after re-login'
  tail makes the recoverability concrete

No code-path changes — just the wording. Backend behavior + endpoint
shape unchanged.

frontend/packages/agent/src/app.js

@@ -222,25 +222,28 @@ window.marked = marked;
     // flips the harness LoginState to NeedsLogin. The turn loop's
     // next iteration parks in wait_for_login; a fresh `claude auth
     // login` from the dashboard re-arms it (#542 mtime resumption).
-    // Destructive — the operator has to re-paste OAuth creds on the
+    // Operator has to re-paste OAuth creds on the login screen after,
-    // login screen after — so we confirm with a clear-eyed prompt.
+    // but the --continue session history is preserved (#584 narrowed
+    // the backend wipe to just .credentials.json + mcp-needs-auth-
+    // cache.json) — so the agent picks up where it left off on the
+    // next turn after re-login.
     const logoutBtn = el('button', {
       type: 'button',
       class: 'overflow-item overflow-item-logout',
       role: 'menuitem',
       id: 'logout-btn',
-      title: 'wipe ~/.claude/ entirely (OAuth creds + projects/*.jsonl --continue history) + park in needs-login until a fresh `claude auth login` runs',
+      title: 'rotate OAuth credentials in ~/.claude/ + park in needs-login until a fresh `claude auth login` runs (--continue session history preserved)',
     },
       el('span', { class: 'overflow-item-icon', 'aria-hidden': 'true' }, '🔓'),
       'logout',
     );
     logoutBtn.addEventListener('click', () => {
       if (!window.confirm(
-        `log ${label} out? this SIGINTs any running claude turn, then WIPES the entire ` +
+        `log ${label} out? this SIGINTs any running claude turn, deletes only the OAuth ` +
-        `~/.claude/ directory — that includes OAuth credentials AND the projects/*.jsonl ` +
+        `credential files (.credentials.json + mcp-needs-auth-cache.json) in ~/.claude/, ` +
-        `session history (--continue context). the agent then parks in 'needs login' until ` +
+        `and parks the agent in 'needs login' until you paste a fresh OAuth code from the ` +
-        `you paste a fresh OAuth code from the login screen. all prior conversation state ` +
+        `login screen. prior --continue session history is preserved — the agent picks up ` +
-        `for this agent is lost. no undo.`
+        `where it left off on the next turn after re-login.`
       )) return;
       logoutBtn.disabled = true;
       closeOverflowMenu();
@@ -393,7 +396,7 @@ window.marked = marked;
     { name: '/compact',     desc: 'compact the persistent claude session' },
     { name: '/model',       desc: '/model <name>  — switch claude model for future turns' },
     { name: '/new-session', desc: 'next turn runs without --continue (fresh claude session)' },
-    { name: '/logout',      desc: 'wipe ~/.claude/ (creds + --continue history) + park in needs-login' },
+    { name: '/logout',      desc: 'rotate OAuth credentials + park in needs-login (--continue session preserved)' },
   ];
 
   async function postModel(name) {
@@ -464,11 +467,11 @@ window.marked = marked;
         return true;
       case '/logout':
         if (window.confirm(
-          `log out? this SIGINTs any running claude turn, then WIPES the entire ` +
+          `log out? this SIGINTs any running claude turn, deletes only the OAuth ` +
-          `~/.claude/ directory — that includes OAuth credentials AND the projects/*.jsonl ` +
+          `credential files (.credentials.json + mcp-needs-auth-cache.json) in ~/.claude/, ` +
-          `session history (--continue context). the agent then parks in 'needs login' until ` +
+          `and parks the agent in 'needs login' until you paste a fresh OAuth code from the ` +
-          `you paste a fresh OAuth code from the login screen. all prior conversation state ` +
+          `login screen. prior --continue session history is preserved — the agent picks up ` +
-          `for this agent is lost. no undo.`
+          `where it left off on the next turn after re-login.`
         )) {
           postLogout();
         }