diff --git a/mcp-server/src/legal_mcp/config.py b/mcp-server/src/legal_mcp/config.py
index daf4158..4ba868c 100644
--- a/mcp-server/src/legal_mcp/config.py
+++ b/mcp-server/src/legal_mcp/config.py
@@ -286,7 +286,12 @@ LESSON_SYNTH_MODEL = os.environ.get("LESSON_SYNTH_MODEL", HALACHA_EXTRACT_MODEL)
 LESSON_SYNTH_EFFORT = os.environ.get("LESSON_SYNTH_EFFORT", "high")
 LESSON_SYNTH_DRIFT_FLOOR = float(os.environ.get("LESSON_SYNTH_DRIFT_FLOOR", "0.80"))
 # Cosine floor for two lessons to land in the same cluster (greedy, within shard).
-LESSON_SYNTH_CLUSTER_THRESHOLD = float(os.environ.get("LESSON_SYNTH_CLUSTER_THRESHOLD", "0.82"))
+# Tuned empirically (#158 dry-run, 81 lessons): the lessons are diverse (median
+# pairwise cosine ~0.48, max ~0.72), so 0.82 merged nothing. 0.68 captures the real
+# near-duplicates (5 faithful clusters across rishuy+betterment, all clearing the
+# 0.80 drift gate) without merging weakly-related lessons; the drift gate is the
+# quality backstop below this.
+LESSON_SYNTH_CLUSTER_THRESHOLD = float(os.environ.get("LESSON_SYNTH_CLUSTER_THRESHOLD", "0.68"))
 
 # Mistral OCR (fallback for scanned PDFs — replaces Google Cloud Vision)
 MISTRAL_API_KEY = os.environ.get("MISTRAL_API_KEY", "")