The sentry_logger hook turns every DebugLogger line into a
breadcrumb, and breadcrumbs ride the per-request transaction
envelope without passing SentryScrubber — so debug dumps of card
content were reaching Sentry.

Assisted-by: GLM-5.3 via pi

diff --git a/config.ru b/config.ru
index 8e2d59f..15c6682 100644
--- a/config.ru
+++ b/config.ru
@@ -36,6 +36,13 @@ Sentry.init do |sentry|
   # locally either way, see ProTacts::UnhandledRequests.
   sentry.before_send = ProTacts::SentryScrubber
 
+  # The debug log is a local-only record of full exchanges, bodies and
+  # all. Sentry's sentry_logger hook would otherwise turn every one of
+  # its lines into a breadcrumb, and breadcrumbs reach Sentry without
+  # passing the scrubber above. Keyed on the progname DebugLogger#write
+  # passes with each line.
+  sentry.exclude_loggers = [ProTacts::DebugLogger::PROGNAME]
+
   sentry.traces_sample_rate = 1.0
 end
 
diff --git a/lib/pro_tacts/debug_logger.rb b/lib/pro_tacts/debug_logger.rb
index 2a4b8e0..211ea64 100644
--- a/lib/pro_tacts/debug_logger.rb
+++ b/lib/pro_tacts/debug_logger.rb
@@ -15,6 +15,13 @@ module ProTacts
     # @rbs @app: Rack::_App
     # @rbs @logger: Logger
 
+    # Identifies this logger's lines to Sentry's sentry_logger
+    # breadcrumb hook, which keys its exclude list on the progname
+    # (see config.ru). Every line here is a local-only record of a
+    # full exchange — bodies included — so none of it may ride to
+    # Sentry as a breadcrumb, where SentryScrubber would never see it.
+    PROGNAME = "ProTacts::DebugLogger" #: String
+
     # Builds the Logger the middleware writes to: appended and unbuffered
     # (Logger syncs its own device), one timestamped line per dump. path
     # "stderr" writes to the process's stderr.
@@ -125,7 +132,11 @@ module ProTacts
     #: (String prefix, String text) -> void
     def write(prefix, text)
       text.to_s.lines(chomp: true).each do |line|
-        @logger.debug("#{prefix} #{line}")
+        # The progname form (block for the message) is what carries
+        # PROGNAME to Logger#add, where Sentry's hook reads it; the
+        # custom formatter ignores it, so the log's format is
+        # unchanged.
+        @logger.debug(PROGNAME) { "#{prefix} #{line}" }
       end
     end
   end