Document shared debug input and reporting mode

docs/internal/overview.md

@@ -38,6 +38,12 @@ collected parser events through that selection. The selected mode therefore
 applies to command execution, help, and version; routing and parsing failures
 remain visible in every mode.
 
+An effective flag view combines a shared application debug binding with the
+core declaration for parsing, help, and completion, while preserving the
+application binding's position. The same occurrence stream selects reporting
+mode independently of the prepared application value. The invocation's mode
+accessor reads the reporter's selection under its existing state mutex.
+
 The reporter owns invocation-scoped visibility, message formatting, managed
 report rendering, delivery observations, and finalization. It presents queued
 messages after the handler returns, then a failed outcome's explanation, and