fix: accept kwargs in capture_exception so $exception_fingerprint is preserved

lib/posthog/client.rb

@@ -222,10 +222,21 @@ def capture(attrs)
 
     # Captures an exception as an event
     #
+    # Supports both positional and keyword argument styles:
+    #   capture_exception(exception, 'user-123', { '$exception_fingerprint' => 'CustomGroup' })
+    #   capture_exception(exception, distinct_id: 'user-123', properties: { '$exception_fingerprint' => 'CustomGroup' })
+    #
     # @param [Exception, String, Object] exception The exception to capture, a string message, or exception-like object
     # @param [String] distinct_id The ID for the user (optional, defaults to a generated UUID)
     # @param [Hash] additional_properties Additional properties to include with the exception event (optional)
-    def capture_exception(exception, distinct_id = nil, additional_properties = {})
+    # @param [Hash] kwargs Keyword form: :distinct_id, :properties
+    def capture_exception(exception, distinct_id = nil, additional_properties = nil, **kwargs)
+      unless kwargs.empty?
+        distinct_id = kwargs[:distinct_id] if distinct_id.nil?
+        additional_properties = kwargs[:properties] if additional_properties.nil?
+      end
+      additional_properties ||= {}
+
       exception_info = ExceptionCapture.build_parsed_exception(exception)
 
       return if exception_info.nil?

posthog-rails/README.md

@@ -131,9 +131,16 @@ PostHog.identify(
 # Track an exception manually
 PostHog.capture_exception(
   exception,
-  current_user.id,
-  { custom_property: 'value' }
+  distinct_id: current_user.id,
+  properties: {
+    custom_property: 'value',
+    # Override exception grouping by setting a fingerprint
+    '$exception_fingerprint' => 'CustomExceptionGroup'
+  }
 )
+
+# The positional form is still supported:
+# PostHog.capture_exception(exception, current_user.id, { custom_property: 'value' })
 ```
 
 ### Background Jobs

spec/posthog/client_spec.rb

@@ -1347,6 +1347,31 @@ def run
         expect(message[:distinct_id].length).to eq(36)
         expect(message[:properties]['$process_person_profile']).to be false
       end
+
+      it 'captures exception via kwargs with $exception_fingerprint' do
+        begin
+          raise StandardError, 'Test exception'
+        rescue StandardError => e
+          client.capture_exception(
+            e,
+            distinct_id: 'user-123',
+            properties: {
+              '$exception_fingerprint' => 'CustomExceptionGroup',
+              'user_agent' => 'Test Agent'
+            }
+          )
+        end
+
+        message = client.dequeue_last_message
+
+        expect(message[:event]).to eq('$exception')
+        expect(message[:distinct_id]).to eq('user-123')
+        expect(message[:properties]['$exception_list'].first['type']).to eq('StandardError')
+        expect(message[:properties]['$exception_list'].first['value']).to eq('Test exception')
+        expect(message[:properties]['$exception_fingerprint']).to eq('CustomExceptionGroup')
+        expect(message[:properties]['user_agent']).to eq('Test Agent')
+        expect(message[:properties]).not_to have_key('$process_person_profile')
+      end
     end
 
     context 'common' do