fix(whatsapp): allow connecting Meta test numbers without a PIN

The WhatsApp config POST handler hard-failed with a 400 whenever a
number needed registration (first save or number change) and no
6-digit two-step-verification PIN was supplied. Meta test numbers
(Developer Console) are pre-registered by Meta and expose no PIN to
set, so test-number users could never complete setup (issue #242).

The PIN-based /{phone_number_id}/register call only governs inbound
webhook routing for production numbers under a shared WABA (issue
#136) — it has nothing to do with credential validity or outbound
sends. So treat it as best-effort: when no PIN is supplied, skip
/register, save the (already Meta-verified) credentials as connected,
and leave registered_at null. The response now reports `registered`
accurately and adds `registration_skipped` so the UI can react.

UI: the save handler no longer falsely claims the number is "Live"
on a skipped registration — it points at the existing "Not
registered" banner, which already offers a PIN-retry path. The PIN
field is relabelled (optional) with copy explaining it's only for
production inbound routing and that test numbers have no PIN.

Fixes #242

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/app/api/whatsapp/config/route.ts

@@ -284,26 +284,32 @@ export async function POST(request: Request) {
 
     // Step 1: register the phone number for inbound webhooks.
     //
-    // Required on first save AND whenever the user supplies a fresh
+    // Attempted on first save AND whenever the user supplies a fresh
     // PIN (e.g. they rotated the 2FA PIN in Meta Manager). Skipped
     // when the same number is already registered and no PIN was
     // supplied — re-registering an already-active number with a
     // stale PIN would actually fail and undo the active subscription.
     let registeredAt: string | null = existing?.registered_at ?? null
     let registrationError: string | null = null
+    // True when registration was deliberately skipped because no PIN
+    // was supplied (see below). Distinct from registrationError — this
+    // is not a failure, just an incomplete-but-valid save.
+    let registrationSkipped = false
 
     const needsRegistration = !sameNumber || (typeof pin === 'string' && pin.length > 0)
     if (needsRegistration) {
       if (!pin) {
-        return NextResponse.json(
-          {
-            error:
-              'Two-step verification PIN is required to subscribe this number to wacrm. ' +
-              'Set a 6-digit PIN in Meta WhatsApp Manager → Phone Numbers → Two-step verification, then paste it below.',
-          },
-          { status: 400 }
-        )
-      }
+        // No PIN provided. Meta TEST numbers (Developer Console) are
+        // pre-registered by Meta and expose no two-step verification
+        // PIN to set, so requiring one made them impossible to connect
+        // (issue #242). The /register + PIN step only matters for
+        // production numbers under a shared WABA (issue #136), so treat
+        // it as best-effort: skip it, save the (already Meta-verified)
+        // credentials as connected, and leave registered_at null. The
+        // UI surfaces a separate "Not registered" banner with a path to
+        // add a PIN later for users who do need inbound webhook routing.
+        registrationSkipped = true
+      } else {
         try {
           await registerPhoneNumber({
             phoneNumberId: phone_number_id,
@@ -321,6 +327,7 @@ export async function POST(request: Request) {
           // not actually live yet.
         }
       }
+    }
 
     // Step 2: subscribe the WABA to this app. Idempotent on Meta's
     // side, so we call on every save and persist the timestamp.
@@ -410,7 +417,12 @@ export async function POST(request: Request) {
     return NextResponse.json({
       success: true,
       saved: true,
-      registered: true,
+      registered: registeredAt != null,
+      // Credentials are valid and saved, but inbound webhook
+      // registration was skipped because no PIN was supplied (e.g. a
+      // Meta test number). The UI shows the "Not registered" banner
+      // rather than claiming the number is fully live.
+      registration_skipped: registrationSkipped,
       phone_info: phoneInfo,
     })
   } catch (error) {

src/components/settings/whatsapp-config.tsx

@@ -233,6 +233,16 @@ export function WhatsAppConfig() {
           `Saved, but Meta couldn't register the number: ${data.registration_error}`,
           { duration: 12000 },
         );
+      } else if (data.registration_skipped) {
+        // Credentials saved + verified, but /register was skipped
+        // because no PIN was supplied (e.g. a Meta test number).
+        // Don't claim the number is "Live" — point at the
+        // Registration status banner instead.
+        toast.success(
+          'Credentials saved and verified. Inbound registration was skipped (no PIN) — see Registration status below.',
+          { duration: 10000 },
+        );
+        setPin('');
       } else {
         toast.success(
           data.phone_info?.verified_name
@@ -604,9 +614,7 @@ export function WhatsAppConfig() {
             <div className="space-y-2">
               <Label className="text-slate-300">
                 Two-step verification PIN
-                {!isRegistered && (
-                  <span className="ml-1 text-red-400">*</span>
-                )}
+                <span className="ml-1 text-slate-500">(optional)</span>
               </Label>
               <Input
                 type="text"
@@ -620,16 +628,19 @@ export function WhatsAppConfig() {
                 className="bg-slate-800 border-slate-700 text-white placeholder:text-slate-500 tracking-widest"
               />
               <p className="text-xs text-slate-500 leading-relaxed">
-                Required the first time you connect a number, and any
-                time you swap to a different number. Set it in{' '}
+                Needed only to wire <strong className="text-slate-300">inbound</strong> messages
+                for a <strong className="text-slate-300">production</strong> number. Set it in{' '}
                 <strong className="text-slate-300">
                   Meta Business Manager → WhatsApp Accounts → Phone
                   Numbers → Two-step verification
                 </strong>
-                . Without this PIN, Meta saves your credentials but
-                won&apos;t actually route inbound messages to wacrm —
-                the symptom that hits second numbers under a shared
-                WABA. Leave blank to keep an existing registration
+                , then paste it here so wacrm can subscribe the number —
+                otherwise Meta routes inbound events to whichever app
+                last claimed it (the symptom that hits second numbers
+                under a shared WABA).{' '}
+                <strong className="text-slate-300">Meta test numbers</strong> have no
+                PIN and are pre-registered — leave this blank for them.
+                Leaving it blank also keeps an existing registration
                 untouched.
               </p>
             </div>