fix(api-tokens): harden rate limiting and surface list-load errors (#1292)

* fix(api-tokens): scope per-token rate limits to live tokens

Forged or token-shaped Authorization headers no longer mint their own
rate-limit budget. The key generator now grants a per-token budget only to
a real, active token and falls back to per-IP keying for anything else, so
a single source cannot evade the global limiter by rotating fake tokens.
The validated token is memoized on the request, so authentication reuses
it without a second database lookup.

Token validation (format, checksum, lookup, revocation, expiry) is now a
single shared helper used by the HTTP auth middleware, the WebSocket
upgrade handler, and the rate-limit key generator, replacing two
near-identical inline copies that could drift apart. The last-used
timestamp write is throttled so a busy token no longer writes to the
database on every request.

* fix(api-tokens): surface token list-load failures with a retry

A failed load of the API tokens list was swallowed: a server error
rendered the empty "no tokens yet" state with no sign that anything went
wrong. The list now shows an error card with a Retry action and raises a
toast on any non-ok response or network error, matching the create and
revoke flows. Adds a troubleshooting entry for the error.

* test(api-tokens): seed tokens via the shared test helper

The new hardening and WS-scope suites computed sha256 of a raw token
directly, which CodeQL flags as js/insufficient-password-hash (a false
positive: these are 256-bit CSPRNG opaque tokens, not passwords). Route
token creation through the existing apiTokenTestHelper and read the stored
token_hash back from the row, so the suites no longer hash anything
themselves. Also removes the duplicated createToken helpers.

* fix(api-tokens): key the rate limiter by the same credential auth uses

The rate-limit key generator checked the session cookie before the
Authorization bearer, while authMiddleware authenticates bearer-over-cookie
(bearerToken || cookieToken). A request could send a Bearer API token plus a
forged cookie and be keyed by the cookie's (forgeable, rotatable) username,
sidestepping the per-token / per-IP keying the limiter applies to API tokens:
a valid token would lose its own bucket, and a forged token-shaped bearer
would no longer collapse to per-IP.

Reorder the generator to mirror auth: process the bearer first (validate the
API token and key per-token or fall back to per-IP; otherwise decode the JWT
by username/sub), and consult the cookie only when there is no bearer.
Regression tests cover a valid and a forged sen_sk_ bearer, each sent with a
forged cookie.

frontend/src/components/ApiTokensSection.tsx

@@ -10,7 +10,7 @@ import { toast } from '@/components/ui/toast-store';
 import { apiFetch } from '@/lib/api';
 import { copyToClipboard } from '@/lib/clipboard';
 import { CapabilityGate } from './CapabilityGate';
-import { Zap, Plus, Copy, Trash2, CheckCircle, RefreshCw, Clock } from 'lucide-react';
+import { Zap, Plus, Copy, Trash2, CheckCircle, RefreshCw, Clock, AlertTriangle } from 'lucide-react';
 import { SettingsPrimaryButton } from './settings/SettingsActions';
 import { SettingsCallout } from './settings/SettingsCallout';
 import { useMastheadStats } from './settings/MastheadStatsContext';
@@ -60,6 +60,7 @@ export function ApiTokensSection() {
     const [showForm, setShowForm] = useState(false);
     const [newToken, setNewToken] = useState<{ id: number; token: string } | null>(null);
     const [revokeTarget, setRevokeTarget] = useState<ApiTokenListItem | null>(null);
+    const [loadError, setLoadError] = useState(false);
 
     const [formName, setFormName] = useState('');
     const [formScope, setFormScope] = useState('read-only');
@@ -71,8 +72,16 @@ export function ApiTokensSection() {
             if (res.ok) {
                 const data: ApiTokenListItem[] = await res.json();
                 setTokens(data.filter(t => !t.revoked_at));
+                setLoadError(false);
+            } else {
+                const err = await res.json().catch(() => ({}));
+                setLoadError(true);
+                toast.error(err?.error || err?.message || 'Failed to load API tokens.');
             }
-        } catch { toast.error('Failed to load API tokens.'); } finally { setLoading(false); }
+        } catch {
+            setLoadError(true);
+            toast.error('Failed to load API tokens.');
+        } finally { setLoading(false); }
     };
 
     // eslint-disable-next-line react-hooks/set-state-in-effect
@@ -224,7 +233,7 @@ export function ApiTokensSection() {
                 )}
 
                 {/* Empty state */}
-                {!loading && tokens.length === 0 && !showForm && (
+                {!loading && !loadError && tokens.length === 0 && !showForm && (
                     <SettingsCallout
                         icon={<Zap className="h-4 w-4" />}
                         title="No API tokens yet"
@@ -232,6 +241,21 @@ export function ApiTokensSection() {
                     />
                 )}
 
+                {/* Load error state */}
+                {!loading && loadError && tokens.length === 0 && !showForm && (
+                    <SettingsCallout
+                        tone="error"
+                        icon={<AlertTriangle className="h-4 w-4" />}
+                        title="Couldn't load API tokens"
+                        subtitle="Check your connection and try again."
+                        action={
+                            <Button variant="outline" size="sm" onClick={() => { setLoading(true); fetchTokens(); }}>
+                                <RefreshCw className="w-4 h-4" strokeWidth={1.5} /> Retry
+                            </Button>
+                        }
+                    />
+                )}
+
                 {/* Token list */}
                 {!loading && tokens.map(token => (
                     <div key={token.id} className="rounded-lg border border-card-border border-t-card-border-top bg-card text-card-foreground shadow-card-bevel transition-colors hover:border-t-card-border-hover p-4 space-y-3">