diff --git a/src/services/relay-selection.ts b/src/services/relay-selection.ts
index 2cc21c7..0437b7c 100644
--- a/src/services/relay-selection.ts
+++ b/src/services/relay-selection.ts
@@ -25,6 +25,7 @@ import type {
   RelaySelectionResult,
   RelaySelectionReasoning,
   RelaySelectionOptions,
+  RelayFilterMap,
 } from "@/types/relay-selection";
 
 /**
@@ -486,6 +487,37 @@ function buildReasoning(
   );
 }
 
+/**
+ * Builds per-relay filter maps for optimized queries
+ *
+ * Groups authors by which relay they should be queried from,
+ * allowing consumers to send only relevant authors to each relay.
+ *
+ * @param selectedPointers - ProfilePointers after optimization (with filtered relays)
+ * @returns Array of per-relay filter mappings
+ */
+function buildPerRelayFilters(
+  selectedPointers: ProfilePointer[],
+): RelayFilterMap[] {
+  // Group authors by relay
+  const relayToAuthors = new Map<string, Set<string>>();
+
+  for (const pointer of selectedPointers) {
+    for (const relay of pointer.relays || []) {
+      if (!relayToAuthors.has(relay)) {
+        relayToAuthors.set(relay, new Set());
+      }
+      relayToAuthors.get(relay)!.add(pointer.pubkey);
+    }
+  }
+
+  // Convert to array
+  return Array.from(relayToAuthors.entries()).map(([relay, authors]) => ({
+    relay,
+    authors: Array.from(authors),
+  }));
+}
+
 /**
  * Creates a fallback result when no pubkeys or all fetches failed
  *
@@ -707,9 +739,13 @@ export async function selectRelaysForFilter(
     pTagPointers,
   );
 
+  // Build per-relay filter maps for optimized queries
+  const perRelayFilters = buildPerRelayFilters(selectedPointers);
+
   return {
     relays,
     reasoning,
     isOptimized: true,
+    perRelayFilters,
   };
 }
diff --git a/src/types/relay-selection.ts b/src/types/relay-selection.ts
index 35ad329..f71df3e 100644
--- a/src/types/relay-selection.ts
+++ b/src/types/relay-selection.ts
@@ -17,6 +17,14 @@ export interface RelaySelectionResult {
 
   /** True if using NIP-65 optimization, false if using fallback */
   isOptimized: boolean;
+
+  /**
+   * Per-relay author mappings for optimized queries (optional)
+   *
+   * When present, consumers can use this to send only relevant
+   * authors to each relay instead of the full authors list.
+   */
+  perRelayFilters?: RelayFilterMap[];
 }
 
 /**
@@ -52,3 +60,17 @@ export interface RelaySelectionOptions {
   /** Timeout in ms for fetching kind:10002 events (default: 1000) */
   timeout?: number;
 }
+
+/**
+ * Per-relay filter mapping for optimized queries
+ *
+ * Instead of sending the same filter to all relays, we can send
+ * only the relevant authors to each relay based on their relay lists.
+ */
+export interface RelayFilterMap {
+  /** Relay URL (normalized) */
+  relay: string;
+
+  /** Authors that should be queried from this relay */
+  authors: string[];
+}