diff --git a/hwe/compare/turn_command_trace.php b/hwe/compare/turn_command_trace.php
index f71dd6c6..0f994a73 100644
--- a/hwe/compare/turn_command_trace.php
+++ b/hwe/compare/turn_command_trace.php
@@ -71,6 +71,159 @@ final class TurnComparisonTracingRNG implements RNG
     }
 }
 
+/** @return array<string, mixed> */
+function comparisonMappedPatch(array $row, array $mapping): array
+{
+    $patch = [];
+    foreach ($mapping as $canonical => $legacy) {
+        if (array_key_exists($canonical, $row)) {
+            $patch[$legacy] = $row[$canonical];
+        }
+    }
+    return $patch;
+}
+
+function comparisonApplyTurnFixtureSetup(mixed $setup): void
+{
+    if ($setup === null) {
+        return;
+    }
+    if (!is_array($setup)) {
+        throw new \InvalidArgumentException('setup must be an object');
+    }
+    $db = DB::db();
+    $world = $setup['world'] ?? null;
+    if ($world !== null) {
+        if (!is_array($world)) {
+            throw new \InvalidArgumentException('setup.world must be an object');
+        }
+        $game = KVStorage::getStorage($db, 'game_env');
+        foreach (['year', 'month', 'startyear'] as $key) {
+            $fixtureKey = $key === 'startyear' ? 'startYear' : $key;
+            if (!array_key_exists($fixtureKey, $world)) {
+                continue;
+            }
+            $value = $world[$fixtureKey];
+            if (!is_int($value) || $value < 1 || ($key === 'month' && $value > 12)) {
+                throw new \InvalidArgumentException("setup.world.{$fixtureKey} is invalid");
+            }
+            $game->setValue($key, $value);
+        }
+        $game->resetCache();
+    }
+
+    foreach (['nations', 'cities', 'generals', 'diplomacy'] as $collection) {
+        if (isset($setup[$collection]) && !is_array($setup[$collection])) {
+            throw new \InvalidArgumentException("setup.{$collection} must be an array");
+        }
+    }
+
+    foreach ($setup['nations'] ?? [] as $row) {
+        if (!is_array($row) || !is_int($row['id'] ?? null) || $row['id'] < 1) {
+            throw new \InvalidArgumentException('setup.nations requires positive integer ids');
+        }
+        $data = comparisonMappedPatch($row, [
+            'id' => 'nation',
+            'name' => 'name',
+            'color' => 'color',
+            'capitalCityId' => 'capital',
+            'gold' => 'gold',
+            'rice' => 'rice',
+            'tech' => 'tech',
+            'level' => 'level',
+            'typeCode' => 'type',
+            'war' => 'war',
+            'generalCount' => 'gennum',
+            'power' => 'power',
+        ]);
+        if (isset($row['meta'])) {
+            $data['aux'] = Json::encode($row['meta']);
+        }
+        $data += [
+            'name' => "fixture-nation-{$row['id']}",
+            'color' => '#777777',
+            'capital' => 0,
+            'gold' => 0,
+            'rice' => 0,
+            'level' => 1,
+            'type' => 'che_중립',
+            'aux' => '{}',
+        ];
+        $db->insertUpdate('nation', $data, $data);
+    }
+
+    foreach ($setup['cities'] ?? [] as $row) {
+        if (!is_array($row) || !is_int($row['id'] ?? null) || $row['id'] < 1) {
+            throw new \InvalidArgumentException('setup.cities requires positive integer ids');
+        }
+        $patch = comparisonMappedPatch($row, [
+            'nationId' => 'nation',
+            'population' => 'pop',
+            'agriculture' => 'agri',
+            'commerce' => 'comm',
+            'security' => 'secu',
+            'supplyState' => 'supply',
+            'frontState' => 'front',
+            'defence' => 'def',
+            'wall' => 'wall',
+            'state' => 'state',
+            'term' => 'term',
+            'trust' => 'trust',
+            'trade' => 'trade',
+        ]);
+        if ($patch !== []) {
+            $db->update('city', $patch, 'city = %i', $row['id']);
+        }
+    }
+
+    foreach ($setup['generals'] ?? [] as $row) {
+        if (!is_array($row) || !is_int($row['id'] ?? null) || $row['id'] < 1) {
+            throw new \InvalidArgumentException('setup.generals requires positive integer ids');
+        }
+        $patch = comparisonMappedPatch($row, [
+            'nationId' => 'nation',
+            'cityId' => 'city',
+            'troopId' => 'troop',
+            'leadership' => 'leadership',
+            'strength' => 'strength',
+            'intelligence' => 'intel',
+            'officerLevel' => 'officer_level',
+            'gold' => 'gold',
+            'rice' => 'rice',
+            'crew' => 'crew',
+            'crewTypeId' => 'crewtype',
+            'train' => 'train',
+            'atmos' => 'atmos',
+            'killTurn' => 'killturn',
+            'npcState' => 'npc',
+        ]);
+        if ($patch !== []) {
+            $db->update('general', $patch, 'no = %i', $row['id']);
+        }
+    }
+
+    foreach ($setup['diplomacy'] ?? [] as $row) {
+        if (
+            !is_array($row) ||
+            !is_int($row['fromNationId'] ?? null) ||
+            !is_int($row['toNationId'] ?? null) ||
+            $row['fromNationId'] < 1 ||
+            $row['toNationId'] < 1
+        ) {
+            throw new \InvalidArgumentException('setup.diplomacy requires positive integer nation ids');
+        }
+        $data = comparisonMappedPatch($row, [
+            'fromNationId' => 'me',
+            'toNationId' => 'you',
+            'state' => 'state',
+            'term' => 'term',
+            'dead' => 'dead',
+        ]);
+        $data += ['state' => 3, 'term' => 0, 'dead' => 0];
+        $db->insertUpdate('diplomacy', $data, $data);
+    }
+}
+
 function comparisonRunTurnCommand(array $request): array
 {
     if (getenv('TURN_DIFFERENTIAL_ENABLED') !== '1') {
@@ -90,6 +243,7 @@ function comparisonRunTurnCommand(array $request): array
         throw new \InvalidArgumentException('action must be a non-empty string');
     }
 
+    comparisonApplyTurnFixtureSetup($request['setup'] ?? null);
     $snapshotRequest = ['observe' => $request['observe'] ?? []];
     $before = comparisonTurnStateSnapshot($snapshotRequest);
     $db = DB::db();