diff --git a/app/Http/Controllers/Business/Pages.php b/app/Http/Controllers/Business/Pages.php
index c870e7cd..c1bb48ba 100644
--- a/app/Http/Controllers/Business/Pages.php
+++ b/app/Http/Controllers/Business/Pages.php
@@ -1320,6 +1320,7 @@ class Pages extends Controller
         $columns = $inventoryPage['directory']['fields'] ?? [];
 
         return response()->streamDownload(function () use ($filters, $columns): void {
+            set_time_limit(0);
             $csv = fopen('php://output', 'w');
             if ($csv === false) {
                 throw new RuntimeException('无法创建进销存报表导出流。');
@@ -1327,6 +1328,7 @@ class Pages extends Controller
 
             fputs($csv, chr(0xEF) . chr(0xBB) . chr(0xBF));
             fputcsv($csv, array_column($columns, 'label'));
+            $written = 0;
             foreach ($this->thirdPartyWarehouseStorage->exportMonthlyInventoryReportRows($filters) as $row) {
                 fputcsv($csv, array_map(function (array $column) use ($row): mixed {
                     $value = data_get($row, $column['name']);
@@ -1337,6 +1339,10 @@ class Pages extends Controller
                             ? ($value === null || $value === '' ? '' : $value)
                             : $this->csvText($value));
                 }, $columns));
+                $written++;
+                if ($written % 500 === 0) {
+                    fflush($csv);
+                }
             }
             fclose($csv);
         }, '进销存报表_' . str_replace('-', '', $filters['month']) . '_' . now()->format('Ymd_His') . '.csv', [
diff --git a/modules/EcommerceFinance/Repositories/ThirdPartyWarehouseStorageMirrorRepository.php b/modules/EcommerceFinance/Repositories/ThirdPartyWarehouseStorageMirrorRepository.php
index 10e07960..2aee8833 100644
--- a/modules/EcommerceFinance/Repositories/ThirdPartyWarehouseStorageMirrorRepository.php
+++ b/modules/EcommerceFinance/Repositories/ThirdPartyWarehouseStorageMirrorRepository.php
@@ -585,12 +585,10 @@ class ThirdPartyWarehouseStorageMirrorRepository
      * @param array<string,mixed> $filters
      * @return Generator<int,object>
      */
-    public function exportMonthlyInventoryReportRows(array $filters, int $batchSize = 2000): Generator
+    public function exportMonthlyInventoryReportRows(array $filters, int $batchSize = 500): Generator
     {
         $batchSize = min(max($batchSize, 1), 5000);
         $page = 1;
-        $exported = 0;
-        $total = null;
         $state = $this->requireReadyState();
 
         while (true) {
@@ -598,12 +596,9 @@ class ThirdPartyWarehouseStorageMirrorRepository
                 $filters,
                 $page,
                 $batchSize,
-                $total === null,
+                false,
                 $state,
             );
-            if ($total === null) {
-                $total = (int) ($result['total'] ?? 0);
-            }
 
             $rows = $result['data'] ?? [];
             if ($rows === []) {
@@ -613,8 +608,7 @@ class ThirdPartyWarehouseStorageMirrorRepository
                 yield $row;
             }
 
-            $exported += count($rows);
-            if ($exported >= $total || count($rows) < $batchSize) {
+            if (count($rows) < $batchSize) {
                 return;
             }
             $page++;
@@ -779,23 +773,64 @@ class ThirdPartyWarehouseStorageMirrorRepository
                     array_merge([$owner], $inventoryWarehouseBindings),
                 );
 
-            $candidateUnion = $authorityCandidates->unionAll($inventoryDimensions);
-            $candidates = $this->connection->query()->fromSub($candidateUnion, 'candidate_rows');
-
-            $pageCandidates = (clone $candidates)
-                ->orderBy('warehouse_provider')->orderBy('wh_id')->orderBy('sku_code')
-                ->forPage($page, $perPage);
             if ($includeTotal) {
-                $pageCandidates->select('candidate_rows.*')->selectRaw('COUNT(*) OVER() AS report_total');
-            }
-            $pairRows = $this->boundedGet(clone $pageCandidates);
-            $total = $includeTotal ? (int) ($pairRows->first()->report_total ?? 0) : 0;
-            if ($pairRows->isEmpty()) {
-                if ($includeTotal && $page > 1) {
-                    $total = $this->boundedCount(clone $authorityRows)
-                        + $this->boundedCount(clone $inventoryDimensions);
+                $candidateUnion = $authorityCandidates->unionAll($inventoryDimensions);
+                $candidates = $this->connection->query()->fromSub($candidateUnion, 'candidate_rows');
+                $pageCandidates = (clone $candidates)
+                    ->orderBy('warehouse_provider')->orderBy('wh_id')->orderBy('sku_code')
+                    ->forPage($page, $perPage)
+                    ->select('candidate_rows.*')->selectRaw('COUNT(*) OVER() AS report_total');
+                $pairRows = $this->boundedGet(clone $pageCandidates);
+                $total = (int) ($pairRows->first()->report_total ?? 0);
+            } else {
+                // Export does not need a total. Page the authoritative baseline and newly
+                // discovered inventory dimensions separately so every batch avoids the
+                // expensive full UNION count/window query.
+                $authorityTotal = $this->boundedCount(clone $authorityRows);
+                $total = 0;
+                $offset = ($page - 1) * $perPage;
+                $remaining = $perPage;
+                $candidatePages = [];
+
+                if ($offset < $authorityTotal) {
+                    $authorityLimit = min($remaining, $authorityTotal - $offset);
+                    $candidatePages[] = (clone $authorityCandidates)
+                        ->orderBy('authority.warehouse_provider')
+                        ->orderBy('wh_id')
+                        ->orderBy('authority.product_code')
+                        ->offset($offset)
+                        ->limit($authorityLimit);
+                    $remaining -= $authorityLimit;
+                    $inventoryOffset = 0;
+                } else {
+                    $inventoryOffset = $offset - $authorityTotal;
                 }
 
+                if ($remaining > 0) {
+                    $candidatePages[] = (clone $inventoryDimensions)
+                        ->orderBy('w.name')
+                        ->orderBy('inventory.wh_id')
+                        ->orderBy('inventory.sku_code')
+                        ->offset($inventoryOffset)
+                        ->limit($remaining);
+                }
+
+                if ($candidatePages === []) {
+                    return [
+                        'data' => [],
+                        'total' => 0,
+                        'state' => $state,
+                        'sync' => $this->syncStatus($state),
+                    ];
+                }
+
+                $pageCandidates = array_shift($candidatePages);
+                foreach ($candidatePages as $candidatePage) {
+                    $pageCandidates->unionAll($candidatePage);
+                }
+                $pairRows = $this->boundedGet(clone $pageCandidates);
+            }
+            if ($pairRows->isEmpty()) {
                 return [
                     'data' => [],
                     'total' => $total,
diff --git a/tests/Unit/EcommerceFinance/ThirdPartyWarehouseStorageMirrorRepositoryTest.php b/tests/Unit/EcommerceFinance/ThirdPartyWarehouseStorageMirrorRepositoryTest.php
index af34e786..13ad5604 100644
--- a/tests/Unit/EcommerceFinance/ThirdPartyWarehouseStorageMirrorRepositoryTest.php
+++ b/tests/Unit/EcommerceFinance/ThirdPartyWarehouseStorageMirrorRepositoryTest.php
@@ -447,6 +447,35 @@ class ThirdPartyWarehouseStorageMirrorRepositoryTest extends TestCase
         $this->assertNotContains('LEGACY-CODE-NOT-IN-CATALOG', $codes);
     }
 
+    public function test_inventory_report_export_reads_roll_forward_rows_without_total_count(): void
+    {
+        $this->markReady();
+        $this->insertProduct('SKU-EXPORT');
+        $this->insertInventory('SKU-EXPORT', 999, '2026-09-11 03:21:00');
+        $this->insertInventoryReportAuthoritativeRow([
+            'source_month' => '2026-07-01',
+            'report_month' => '2026-07-01',
+            'warehouse_provider' => '三方-南昌樵舍仓',
+            'warehouse' => '三方-南昌樵舍仓主仓',
+            'product_code' => 'SKU-EXPORT',
+            'opening_quantity' => 10,
+            'closing_quantity' => 12,
+        ]);
+        $this->insertMovement('SKU-EXPORT', '采购进仓', 3, 1, '2026-08-02 10:00:00');
+
+        $rows = iterator_to_array($this->repository->exportMonthlyInventoryReportRows([
+            'month' => '2026-08',
+            'product_code' => 'SKU-EXPORT',
+            'warehouse_provider' => '',
+            'category' => '',
+        ], 1), false);
+
+        $this->assertCount(1, $rows);
+        $this->assertSame('SKU-EXPORT', $rows[0]->product_code);
+        $this->assertSame(12.0, (float) $rows[0]->opening_quantity);
+        $this->assertSame(15.0, (float) $rows[0]->closing_quantity);
+    }
+
     public function test_third_party_page_remains_ready_when_only_the_all_warehouse_dimension_is_missing(): void
     {
         $this->markReady();