store the pin in provider config

app/controllers/api/v1/accounts/whatsapp/callbacks_controller.rb

@@ -47,8 +47,8 @@ class Api::V1::Accounts::Whatsapp::CallbacksController < Api::V1::Accounts::Base
     Rails.logger.error("[WHATSAPP] Embedded signup processing error: #{error.message}")
     Rails.logger.error(error.backtrace.join("\n"))
     render json: {
-      error: 'Internal server error',
+      error: 'signup_failed',
       message: error.message
-    }, status: :internal_server_error
+    }, status: :bad_request
   end
 end

app/services/whatsapp/webhook_setup_service.rb

@@ -21,14 +21,30 @@ class Whatsapp::WebhookSetupService
   end
 
   def register_phone_number
-    # Generate a random 6-digit PIN
-    pin = SecureRandom.random_number(900_000) + 100_000
     phone_number_id = @channel.provider_config['phone_number_id']
+    pin = fetch_or_create_pin
 
     @api_client.register_phone_number(phone_number_id, pin)
+    store_pin(pin)
   rescue StandardError => e
-    Rails.logger.error("[WHATSAPP] Phone registration failed: #{e.message}")
+    Rails.logger.warn("[WHATSAPP] Phone registration failed but continuing: #{e.message}")
     # Continue with webhook setup even if registration fails
+    # This is just a warning, not a blocking error
+  end
+
+  def fetch_or_create_pin
+    # Check if we have a stored PIN for this phone number
+    existing_pin = @channel.provider_config['verification_pin']
+    return existing_pin.to_i if existing_pin.present?
+
+    # Generate a new 6-digit PIN if none exists
+    SecureRandom.random_number(900_000) + 100_000
+  end
+
+  def store_pin(pin)
+    # Store the PIN in provider_config for future use
+    @channel.provider_config['verification_pin'] = pin
+    @channel.save!
   end
 
   def setup_webhook

spec/services/whatsapp/webhook_setup_service_spec.rb

@@ -31,6 +31,7 @@ describe Whatsapp::WebhookSetupService do
         allow(api_client).to receive(:subscribe_waba_webhook)
           .with(waba_id, anything, 'test_verify_token')
           .and_return({ 'success' => true })
+        allow(channel).to receive(:save!)
       end
 
       it 'registers the phone number' do
@@ -97,5 +98,22 @@ describe Whatsapp::WebhookSetupService do
         expect { service.perform }.to raise_error(ArgumentError, 'Access token is required')
       end
     end
+
+    context 'when PIN already exists' do
+      before do
+        channel.provider_config['verification_pin'] = 123_456
+        allow(api_client).to receive(:register_phone_number)
+        allow(api_client).to receive(:subscribe_waba_webhook).and_return({ 'success' => true })
+        allow(channel).to receive(:save!)
+      end
+
+      it 'reuses existing PIN' do
+        with_modified_env FRONTEND_URL: 'https://app.chatwoot.com' do
+          expect(api_client).to receive(:register_phone_number).with('123456789', 123_456)
+          expect(SecureRandom).not_to receive(:random_number)
+          service.perform
+        end
+      end
+    end
   end
 end