diff --git a/cmd/server/neighbor_graph.go b/cmd/server/neighbor_graph.go
index 55b40d86..452fe7d9 100644
--- a/cmd/server/neighbor_graph.go
+++ b/cmd/server/neighbor_graph.go
@@ -24,6 +24,10 @@ const (
 	affinityConfidenceRatio = 3.0
 	// Minimum observation count to auto-resolve.
 	affinityMinObservations = 3
+	// Source-diversity saturation: edges contributed by this many distinct
+	// observers (or more) earn full confidence weight (multiplier 1.0).
+	// Fewer observers earn a proportional fraction. Issue #1229 (Option C).
+	affinityObserverSaturation = 3.0
 )
 
 // affinityLambda = ln(2) / half-life-hours, precomputed.
@@ -78,14 +82,20 @@ func (e *NeighborEdge) Score(now time.Time) float64 {
 //
 // Formula: min(1.0, max(1, |Observers|) / affinityObserverSaturation).
 // With saturation=3, a single observer yields 1/3, two observers 2/3, and
-// three-or-more observers saturate at 1.0 — full historical weight.
-//
-// STUB: real implementation lands in the GREEN commit. Returning 1.0 here
-// keeps the resolver behavior identical so the RED test fails on the
-// behavioral assertion (resolver picks the wrong candidate), not on a
-// missing method.
+// three-or-more observers saturate at 1.0 — full historical weight. Edges
+// with an empty observer set (legacy persisted rows lacking the column;
+// see neighbor_persist.go backward-compat) default to a count of 1 so they
+// behave like single-observer edges rather than disappearing — defensive.
 func (e *NeighborEdge) Confidence() float64 {
-	return 1.0
+	n := float64(len(e.Observers))
+	if n < 1 {
+		n = 1
+	}
+	c := n / affinityObserverSaturation
+	if c > 1.0 {
+		c = 1.0
+	}
+	return c
 }
 
 // AvgSNR returns the average SNR, or 0 if no samples.
diff --git a/cmd/server/store.go b/cmd/server/store.go
index fab11484..2c7da84e 100644
--- a/cmd/server/store.go
+++ b/cmd/server/store.go
@@ -5606,6 +5606,16 @@ func (pm *prefixMap) resolveWithContext(hop string, contextPubkeys []string, gra
 	// highest-affinity candidate among them. Raw score is appropriate because
 	// it reflects both observation frequency and recency, which are the right
 	// signals for "which candidate is this hop most likely referring to."
+	//
+	// Issue #1229 (Option C): the raw score is further multiplied by
+	// e.Confidence() — a source-diversity factor in (0,1] derived from the
+	// number of distinct observers that contributed to the edge. Edges seen
+	// by a single observer are discounted to 1/3 weight; edges seen by ≥3
+	// observers saturate at full weight. This stacks with the geo-rejection
+	// filter merged for #1228 to give two independent lines of defense
+	// against cross-region prefix-collision pollution. Backward-compatible
+	// with the persistence format: legacy edges with empty Observers sets
+	// fall back to single-observer weight.
 	if graph != nil && len(contextPubkeys) > 0 {
 		type scored struct {
 			idx   int
@@ -5629,7 +5639,7 @@ func (pm *prefixMap) resolveWithContext(hop string, contextPubkeys []string, gra
 						otherPK = e.NodeB
 					}
 					if strings.EqualFold(otherPK, candPK) {
-						s := e.Score(now)
+						s := e.Score(now) * e.Confidence()
 						if s > bestScore {
 							bestScore = s
 							bestCount = e.Count