feat(transport): Handle HTTP 413 response for oversized envelopes (#2885)

When Relay returns HTTP 413 (Content Too Large), the SDK now logs a
specific warning message and records client reports with reason
"send_error" for the dropped items. The 413 is not retried since the
data is definitively too large.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: sl0thentr0py

sentry-ruby/lib/sentry/exceptions.rb

@@ -6,4 +6,7 @@ class Error < StandardError
 
   class ExternalError < Error
   end
+
+  class SizeExceededError < ExternalError
+  end
 end

sentry-ruby/lib/sentry/transport.rb

@@ -19,7 +19,8 @@ class Transport
       :before_send,
       :event_processor,
       :insufficient_data,
-      :backpressure
+      :backpressure,
+      :send_error
     ]
 
     include LoggingHelper
@@ -61,6 +62,10 @@ def send_envelope(envelope)
         log_debug("[Transport] Sending envelope with items [#{serialized_items.map(&:type).join(', ')}] #{envelope.event_id} to Sentry")
         send_data(data)
       end
+    rescue Sentry::SizeExceededError
+      serialized_items&.each do |item|
+        record_lost_event(:send_error, item.data_category)
+      end
     end
 
     def serialize_envelope(envelope)

sentry-ruby/lib/sentry/transport/http_transport.rb

@@ -49,6 +49,12 @@ def send_data(data)
 
       if response.code.match?(/\A2\d{2}/)
         handle_rate_limited_response(response) if has_rate_limited_header?(response)
+      elsif response.code == "413"
+        error_message = "HTTP 413: Envelope dropped due to exceeded size limit"
+        error_message += " (body: #{response.body})" if response.body && !response.body.empty?
+        log_warn(error_message)
+
+        raise Sentry::SizeExceededError, error_message
       elsif response.code == "429"
         log_debug("the server responded with status 429")
         handle_rate_limited_response(response)

sentry-ruby/spec/sentry/transport/http_transport_spec.rb

@@ -291,6 +291,79 @@
   end
 
   describe "failed request handling" do
+    context "receive 413 response" do
+      let(:string_io) { StringIO.new }
+
+      before do
+        configuration.sdk_logger = Logger.new(string_io)
+      end
+
+      context "with response body" do
+        let(:fake_response) { build_fake_response("413", body: { detail: "Envelope too large" }) }
+
+        it "raises SizeExceededError with body in message" do
+          sentry_stub_request(fake_response)
+
+          expect { subject.send_data(data) }.to raise_error(
+            Sentry::SizeExceededError,
+            /HTTP 413: Envelope dropped due to exceeded size limit.*body:.*Envelope too large/
+          )
+        end
+
+        it "logs a warning message with body" do
+          sentry_stub_request(fake_response)
+
+          expect { subject.send_data(data) }.to raise_error(Sentry::SizeExceededError)
+          expect(string_io.string).to include("HTTP 413: Envelope dropped due to exceeded size limit")
+          expect(string_io.string).to include("Envelope too large")
+        end
+      end
+
+      context "with empty response body" do
+        let(:fake_response) do
+          Net::HTTPResponse.new("1.0", "413", "").tap do |response|
+            allow(response).to receive(:body).and_return("")
+          end
+        end
+
+        it "raises SizeExceededError without body in message" do
+          sentry_stub_request(fake_response)
+
+          expect { subject.send_data(data) }.to raise_error(
+            Sentry::SizeExceededError,
+            "HTTP 413: Envelope dropped due to exceeded size limit"
+          )
+        end
+      end
+
+      context "records client reports via send_envelope" do
+        let(:fake_response) { build_fake_response("413", body: { detail: "too large" }) }
+
+        it "records send_error for each item in the envelope" do
+          sentry_stub_request(fake_response)
+
+          configuration.send_client_reports = true
+          transport = Sentry::HTTPTransport.new(configuration)
+          envelope = transport.envelope_from_event(event)
+
+          transport.send_envelope(envelope)
+
+          # Should have recorded send_error for the event item
+          expect(transport.discarded_events[[:send_error, "error"]]).to eq(1)
+        end
+
+        it "does not raise the error to the caller" do
+          sentry_stub_request(fake_response)
+
+          configuration.send_client_reports = true
+          transport = Sentry::HTTPTransport.new(configuration)
+          envelope = transport.envelope_from_event(event)
+
+          expect { transport.send_envelope(envelope) }.not_to raise_error
+        end
+      end
+    end
+
     context "receive 4xx responses" do
       let(:fake_response) { build_fake_response("404") }