refactor: Update health check service to use undici's fetch for improved HTTP probing and enhance FormFieldSimple component with optional hint prop

apps/api/src/services/health-check-service.ts

@@ -1,5 +1,5 @@
 import { connect } from "node:net";
-import { Agent } from "undici";
+import { Agent, fetch as undiciFetch } from "undici";
 import type { Db } from "@cfdm/db";
 import { repos } from "@cfdm/db";
 import type { HealthCheckTarget, IpHealthState } from "@cfdm/shared";
@@ -67,14 +67,13 @@ async function httpProbe(
   const path = target.path?.trim() || "/";
   const pathWithSlash = path.startsWith("/") ? path : `/${path}`;
   const port = target.port ?? 80;
-  const hostHeader = target.hostname || ip;
   const useTls = port === 443;
-  // For HTTPS probing against a raw IP, set SNI/Host so TLS handshake and vhost routing work.
-  const authorityHost = target.hostname || ip;
-  const url = useTls
-    ? `https://${authorityHost}${pathWithSlash}`
-    : `http://${ip}${pathWithSlash}`;
-  // Custom dispatcher for HTTPS-to-IP: connect to the literal IP, but present hostname via SNI.
+  // For HTTPS on 443, probe via the hostname (URL host = hostname) so TLS SNI, Host header
+  // and any edge/vhost protection (e.g. Cloudflare origin 421 on direct-IP) all line up.
+  // For multi-A records this loses strict per-IP HTTPS granularity — use TCP probe for that.
+  // For plain HTTP we still hit the literal IP (per-record target).
+  const urlHost = useTls ? target.hostname || ip : ip;
+  const url = `${useTls ? "https" : "http"}://${urlHost}${pathWithSlash}`;
   const dispatcher =
     useTls && target.hostname
       ? new Agent({
@@ -85,12 +84,11 @@ async function httpProbe(
         })
       : undefined;
   try {
-    const response = await fetch(url, {
+    const response = await undiciFetch(url, {
       method: "GET",
-      headers: { Host: hostHeader },
+      headers: { Host: target.hostname || ip },
       signal: AbortSignal.timeout(timeoutMs),
       redirect: "manual",
-      // @ts-expect-error undici dispatcher option is not in fetch types
       dispatcher,
     });
     const latency = Date.now() - started;

apps/web/src/components/form-field.tsx

@@ -63,6 +63,7 @@ interface FormFieldSimpleProps {
   label: string
   htmlFor: string
   error?: { message?: string }
+  hint?: string
   className?: string
   children: ReactNode
 }
@@ -71,6 +72,7 @@ export function FormFieldSimple({
   label,
   htmlFor,
   error,
+  hint,
   className,
   children,
 }: FormFieldSimpleProps) {
@@ -78,6 +80,9 @@ export function FormFieldSimple({
     <Field data-invalid={!!error} className={cn(className)}>
       <FieldLabel htmlFor={htmlFor}>{label}</FieldLabel>
       {children}
+      {hint && !error && (
+        <p className="text-xs text-muted-foreground">{hint}</p>
+      )}
       <FieldError errors={[error]} />
     </Field>
   )

apps/web/src/components/health-check-config-fields.tsx

@@ -141,10 +141,11 @@ export function HealthCheckConfigFields({
               <FormFieldSimple
                 label="HTTP path"
                 htmlFor={`${idPrefix}-path`}
+                hint="Опционально. По умолчанию проверяется /"
               >
                 <AppInput
                   id={`${idPrefix}-path`}
-                  placeholder="/health"
+                  placeholder="/"
                   value={value.path ?? ''}
                   onChange={(e) =>
                     patch({ path: e.target.value === '' ? null : e.target.value })