fix(transport): clamp retry_delay to zero for past Retry-After timestamps

lib/context_dev/internal/transport/base_client.rb

@@ -335,17 +335,17 @@ def initialize(
         private def retry_delay(headers, retry_count:)
           # Non-standard extension
           span = Float(headers["retry-after-ms"], exception: false)&.then { _1 / 1000 }
-          return span if span
+          return [span, 0.0].max if span
 
           retry_header = headers["retry-after"]
-          return span if (span = Float(retry_header, exception: false))
+          return [span, 0.0].max if (span = Float(retry_header, exception: false))
 
           span = retry_header&.then do
             Time.httpdate(_1) - Time.now
           rescue ArgumentError
             nil
           end
-          return span if span
+          return [span, 0.0].max if span
 
           scale = retry_count**2
           jitter = 1 - (0.25 * rand)

test/context_dev/client_test.rb

@@ -120,6 +120,27 @@ def test_client_retry_after_date
     assert_in_delta(10, Thread.current.thread_variable_get(:mock_sleep).last, 1.0)
   end
 
+  def test_client_retry_after_past_date
+    time_now = Time.now
+
+    stub_request(:post, "http://localhost/web/scrape").to_return_json(
+      status: 500,
+      headers: {"retry-after" => (time_now - 60).httpdate},
+      body: {}
+    )
+
+    context_dev = ContextDev::Client.new(base_url: "http://localhost", api_key: "My API Key", max_retries: 1)
+
+    Thread.current.thread_variable_set(:time_now, time_now)
+    assert_raises(ContextDev::Errors::InternalServerError) do
+      context_dev.web.scrape(formats: {}, url: "https://example.com")
+    end
+    Thread.current.thread_variable_set(:time_now, nil)
+
+    assert_requested(:any, /./, times: 2)
+    assert_equal([0.0], Thread.current.thread_variable_get(:mock_sleep))
+  end
+
   def test_client_retry_after_ms
     stub_request(:post, "http://localhost/web/scrape").to_return_json(
       status: 500,