diff --git a/lib/graph/current-understanding-synthesis.js b/lib/graph/current-understanding-synthesis.js
index c39f48e..36a4c46 100644
--- a/lib/graph/current-understanding-synthesis.js
+++ b/lib/graph/current-understanding-synthesis.js
@@ -164,7 +164,7 @@ ${findingsSections.length > 0
 
 Rules for this synthesis:
 1. Current Understanding describes only established or supported understanding from the evidence supplied here.
-2. Do not introduce or describe open questions, unresolved uncertainties, assumptions, provisional hypotheses, speculative explanations, or future investigation needs.
+2. Do not introduce or describe open questions, unresolved uncertainties, assumptions, provisional hypotheses, speculative explanations, or future investigation needs. You may acknowledge a specific gap in established evidence when that lack of knowledge is itself supported by the investigation. Such acknowledgments must not imply a probable outcome, introduce unsupported uncertainty, or direct further investigation.
 3. Produce exactly ONE coherent narrative paragraph (or short multi-sentence paragraph) that represents the Current Understanding of the situation.
 4. Synthesize all provided evidence into a unified understanding — do not list or append findings. The result should read as a natural summary, not a bullet list.
 5. This is a FRESH synthesis from the complete set of inputs above. Do NOT treat any previous Current Understanding as input or authority. Do NOT append to prior summaries.