Allow idempotent reconfirmation of resolved investigation questions

docs/investigation-loop-v1.md

@@ -205,3 +205,10 @@ crashes after evidence publication, external test confirmation and byte-preservi
 output. The BUG-20 integration uses actual wowdiag/wowsrc data and simulated model
 decisions; it tests orchestration, not real model reasoning or discovery of the
 known fix. No paid/cloud model is called by these tests.
+
+Question resolution is idempotent: reconfirming an already resolved question
+does not invalidate an otherwise valid decision and needs no new evidence.
+Resolving any still-open question requires evidence references. Unknown question
+IDs invalidate the entire decision before assessments, tools or budget changes
+are applied. Mixing old confirmations with new resolutions follows the same
+rules; existing question history is preserved.