diff --git a/hwe/compare/turn_state_snapshot.php b/hwe/compare/turn_state_snapshot.php
index 831676e4..6562f19c 100644
--- a/hwe/compare/turn_state_snapshot.php
+++ b/hwe/compare/turn_state_snapshot.php
@@ -115,6 +115,36 @@ function comparisonNationCooldownSelectors(mixed $value, string $label): array
     return array_values($result);
 }
 
+/** @return list<array{fromNationId: int, toNationId: int}> */
+function comparisonDiplomacyPairSelectors(mixed $value, string $label): array
+{
+    if ($value === null) {
+        return [];
+    }
+    if (!is_array($value)) {
+        throw new \InvalidArgumentException("{$label} must be an array");
+    }
+    $result = [];
+    foreach ($value as $entry) {
+        if (!is_array($entry)) {
+            throw new \InvalidArgumentException("{$label} entries must be objects");
+        }
+        $fromNationId = $entry['fromNationId'] ?? null;
+        $toNationId = $entry['toNationId'] ?? null;
+        if (!is_int($fromNationId) || $fromNationId < 1 || !is_int($toNationId) || $toNationId < 1) {
+            throw new \InvalidArgumentException(
+                "{$label} entries require positive fromNationId and toNationId",
+            );
+        }
+        $result["{$fromNationId}:{$toNationId}"] = [
+            'fromNationId' => $fromNationId,
+            'toNationId' => $toNationId,
+        ];
+    }
+    ksort($result, SORT_STRING);
+    return array_values($result);
+}
+
 /** @param array<string, mixed> $row */
 function comparisonPickRow(array $row, array $mapping, array $jsonKeys = []): array
 {
@@ -168,6 +198,10 @@ function comparisonTurnStateSnapshot(array $request): array
         $observe['nationCooldowns'] ?? [],
         'nationCooldowns',
     );
+    $diplomacyPairSelectors = comparisonDiplomacyPairSelectors(
+        $observe['diplomacyPairs'] ?? [],
+        'diplomacyPairs',
+    );
     if (!is_int($logAfterId) || $logAfterId < 0 || !is_int($messageAfterId) || $messageAfterId < 0) {
         throw new \InvalidArgumentException('logAfterId and messageAfterId must be non-negative integers');
     }
@@ -363,26 +397,38 @@ function comparisonTurnStateSnapshot(array $request): array
         comparisonRowsById('nation', 'nation', $nationIds),
     );
 
-    $diplomacy = [];
+    $diplomacyPairs = [];
     foreach ($nationIds as $fromNationId) {
         foreach ($nationIds as $toNationId) {
             if ($fromNationId === $toNationId) {
                 continue;
             }
-            $row = $db->queryFirstRow(
-                'SELECT me, you, state, term, dead FROM diplomacy WHERE me = %i AND you = %i',
-                $fromNationId,
-                $toNationId,
-            );
-            if ($row !== null) {
-                $diplomacy[] = comparisonPickRow($row, [
-                    'fromNationId' => 'me',
-                    'toNationId' => 'you',
-                    'state' => 'state',
-                    'term' => 'term',
-                    'dead' => 'dead',
-                ]);
-            }
+            $diplomacyPairs["{$fromNationId}:{$toNationId}"] = [
+                'fromNationId' => $fromNationId,
+                'toNationId' => $toNationId,
+            ];
+        }
+    }
+    foreach ($diplomacyPairSelectors as $pair) {
+        $diplomacyPairs["{$pair['fromNationId']}:{$pair['toNationId']}"] = $pair;
+    }
+    ksort($diplomacyPairs, SORT_STRING);
+
+    $diplomacy = [];
+    foreach ($diplomacyPairs as $pair) {
+        $row = $db->queryFirstRow(
+            'SELECT me, you, state, term, dead FROM diplomacy WHERE me = %i AND you = %i',
+            $pair['fromNationId'],
+            $pair['toNationId'],
+        );
+        if ($row !== null) {
+            $diplomacy[] = comparisonPickRow($row, [
+                'fromNationId' => 'me',
+                'toNationId' => 'you',
+                'state' => 'state',
+                'term' => 'term',
+                'dead' => 'dead',
+            ]);
         }
     }