task-64: transient payload 压缩改为直接 gzip 二进制流上传

- RustfsObjectStorageService 新增 uploadBytes/readObjectBytes 二进制流 API
  （application/gzip），uploadText/readObjectAsString 改为其薄包装
- TransientPayloadStorageService 的 encodeStoredPayload 直接输出 gzip 字节，
  不再经过 gzip64 + Base64 文本编码（消除 33% 体积膨胀与中间字符串副本）
- 读取端按 gzip magic 识别二进制流解压；兼容旧 gzip64: 文本与历史裸文本
- 本地回落文件同步改为写二进制（Files.write），超限判定基于 gzip 后字节数

backend-java/src/main/java/com/nanri/aiimage/modules/file/service/object/RustfsObjectStorageService.java

@@ -80,12 +80,17 @@ public class RustfsObjectStorageService {
     }
 
     public String uploadText(String objectKey, String content, boolean verifyAfterUpload) {
+        byte[] bytes = Objects.requireNonNullElse(content, "").getBytes(StandardCharsets.UTF_8);
+        return uploadBytes(objectKey, bytes, verifyAfterUpload);
+    }
+
+    public String uploadBytes(String objectKey, byte[] content, boolean verifyAfterUpload) {
         long deadlineNanos = operationDeadlineNanos();
         if (!isConfigured()) {
             throw new IllegalStateException("transient storage is not configured");
         }
         rejectIfCircuitOpen(OP_UPLOAD, objectKey);
-        byte[] bytes = Objects.requireNonNullElse(content, "").getBytes(StandardCharsets.UTF_8);
+        byte[] bytes = content == null ? new byte[0] : content;
         recordPayloadBytes(bytes.length);
         AtomicBoolean putCompleted = new AtomicBoolean();
         try {
@@ -96,7 +101,7 @@ public class RustfsObjectStorageService {
                             .bucket(properties.getBucket())
                             .object(objectKey)
                             .stream(stream, bytes.length, -1)
-                            .contentType("application/json")
+                            .contentType("application/gzip")
                             .build());
                     putCompleted.set(true);
                     return objectKey;
@@ -117,6 +122,11 @@ public class RustfsObjectStorageService {
     }
 
     public String readObjectAsString(String objectKey) {
+        byte[] bytes = readObjectBytes(objectKey);
+        return new String(bytes, StandardCharsets.UTF_8);
+    }
+
+    public byte[] readObjectBytes(String objectKey) {
         long deadlineNanos = operationDeadlineNanos();
         if (!isConfigured()) {
             throw new IllegalStateException("transient storage is not configured");
@@ -128,7 +138,7 @@ public class RustfsObjectStorageService {
                     .bucket(properties.getBucket())
                     .object(objectKey)
                     .build())) {
-                return new String(stream.readAllBytes(), StandardCharsets.UTF_8);
+                return stream.readAllBytes();
             }
         });
     }

backend-java/src/main/java/com/nanri/aiimage/modules/task/service/TransientPayloadStorageService.java

@@ -145,13 +145,16 @@ public class TransientPayloadStorageService {
                             "transient payload only exists on instance=" + ownerInstance
                                     + " current=" + instanceMetadata.getInstanceId());
                 }
-                return decodeStoredPayload(readLocalPayload(stripLocalInstanceId(localKey)));
+                return decodeStoredPayloadBytes(readLocalPayloadBytes(stripLocalInstanceId(localKey)));
             }
             if (pointer.startsWith(RUSTFS_POINTER_PREFIX)) {
-                return decodeStoredPayload(rustfsObjectStorageService.readObjectAsString(pointer.substring(RUSTFS_POINTER_PREFIX.length())));
+                return decodeStoredPayloadBytes(
+                        rustfsObjectStorageService.readObjectBytes(pointer.substring(RUSTFS_POINTER_PREFIX.length())));
             }
             if (pointer.startsWith(OSS_POINTER_PREFIX)) {
-                return decodeStoredPayload(ossStorageService.readObjectAsString(pointer.substring(OSS_POINTER_PREFIX.length())));
+                return decodeStoredPayloadBytes(
+                        ossStorageService.readObjectAsString(pointer.substring(OSS_POINTER_PREFIX.length()))
+                                .getBytes(StandardCharsets.UTF_8));
             }
         } catch (Exception ex) {
             throw new IllegalStateException(errorMessage + ": " + pointer, ex);
@@ -318,8 +321,8 @@ public class TransientPayloadStorageService {
                     category, moduleType, taskId, objectKey, rawBytes, properties.getWarnPayloadBytes());
         }
         boolean rawOversize = isPositiveLimit(properties.getMaxPayloadBytes()) && rawBytes > properties.getMaxPayloadBytes();
-        String storedContent = encodeStoredPayload(content);
+        byte[] storedContent = encodeStoredPayload(content);
-        long storedBytes = payloadBytes(storedContent);
+        long storedBytes = storedContent.length;
         boolean storedOversize = isPositiveLimit(properties.getMaxStoredPayloadBytes()) && storedBytes > properties.getMaxStoredPayloadBytes();
         if (rawOversize || storedOversize) {
             log.warn("[transient-payload] payload size exceeds rustfs limit category={} moduleType={} taskId={} objectKey={} rawBytes={} storedBytes={} maxRawBytes={} maxStoredBytes={} fallbackToLocal={}",
@@ -333,7 +336,7 @@ public class TransientPayloadStorageService {
         boolean rustfsFallbackToLocal = rawOversize || storedOversize;
         if (!rustfsFallbackToLocal && rustfsObjectStorageService.isConfigured()) {
             try {
-                pointer = RUSTFS_POINTER_PREFIX + rustfsObjectStorageService.uploadText(objectKey, storedContent, verifyAfterUpload);
+                pointer = RUSTFS_POINTER_PREFIX + rustfsObjectStorageService.uploadBytes(objectKey, storedContent, verifyAfterUpload);
             } catch (Exception ex) {
                 rustfsFallbackToLocal = true;
                 // 升级为 ERROR：rustfs 失败后只能落到本地，多实例下其他节点读不到，必须能告警。
@@ -362,7 +365,7 @@ public class TransientPayloadStorageService {
         }
     }
 
-    private String storeLocal(String objectKey, String content) {
+    private String storeLocal(String objectKey, byte[] content) {
         try {
             Path root = localPayloadRoot();
             Path target = root.resolve(objectKey).normalize();
@@ -370,9 +373,8 @@ public class TransientPayloadStorageService {
                 throw new IllegalArgumentException("invalid local payload key: " + objectKey);
             }
             Files.createDirectories(target.getParent());
-            Files.writeString(target,
+            Files.write(target,
-                    content == null ? "" : content,
+                    content == null ? new byte[0] : content,
-                    StandardCharsets.UTF_8,
                     StandardOpenOption.CREATE,
                     StandardOpenOption.TRUNCATE_EXISTING,
                     StandardOpenOption.WRITE);
@@ -385,10 +387,10 @@ public class TransientPayloadStorageService {
         }
     }
 
-    private String readLocalPayload(String objectKey) {
+    private byte[] readLocalPayloadBytes(String objectKey) {
         try {
             Path target = resolveLocalPayloadPath(objectKey);
-            return Files.readString(target, StandardCharsets.UTF_8);
+            return Files.readAllBytes(target);
         } catch (Exception ex) {
             throw new IllegalStateException("failed to read local transient payload", ex);
         }
@@ -435,14 +437,18 @@ public class TransientPayloadStorageService {
         return normalized.replaceAll("[^A-Za-z0-9_.\\-]", "_");
     }
 
-    private String encodeStoredPayload(String content) {
+    /**
+     * 压缩 transient payload 为 gzip 二进制流（不再经过 base64 文本编码）。
+     * 极小内容 gzip 可能膨胀，属预期：压缩收益以可压缩内容为准，读取端按 magic 自动识别。
+     */
+    private byte[] encodeStoredPayload(String content) {
         try {
             byte[] raw = Objects.requireNonNullElse(content, "").getBytes(StandardCharsets.UTF_8);
-            ByteArrayOutputStream baos = new ByteArrayOutputStream();
+            ByteArrayOutputStream baos = new ByteArrayOutputStream(Math.max(32, raw.length / 2));
             try (GZIPOutputStream gzip = new GZIPOutputStream(baos)) {
                 gzip.write(raw);
             }
-            return "gzip64:" + Base64.getEncoder().encodeToString(baos.toByteArray());
+            return baos.toByteArray();
         } catch (Exception ex) {
             throw new IllegalStateException("failed to encode transient payload", ex);
         }
@@ -456,21 +462,36 @@ public class TransientPayloadStorageService {
         return value > 0L;
     }
 
-    private String decodeStoredPayload(String storedContent) {
+    private String decodeStoredPayloadBytes(byte[] storedContent) {
-        if (storedContent == null || storedContent.isBlank()) {
+        if (storedContent == null || storedContent.length == 0) {
-            return storedContent;
+            return "";
         }
-        if (!storedContent.startsWith("gzip64:")) {
+        if (isGzip(storedContent)) {
-            return storedContent;
+            try (GZIPInputStream gzip = new GZIPInputStream(new ByteArrayInputStream(storedContent))) {
-        }
-        try {
-            byte[] compressed = Base64.getDecoder().decode(storedContent.substring("gzip64:".length()));
-            try (GZIPInputStream gzip = new GZIPInputStream(new ByteArrayInputStream(compressed))) {
                 return new String(gzip.readAllBytes(), StandardCharsets.UTF_8);
+            } catch (Exception ex) {
+                throw new IllegalStateException("failed to decode transient payload", ex);
             }
-        } catch (Exception ex) {
-            throw new IllegalStateException("failed to decode transient payload", ex);
         }
+        String legacyText = new String(storedContent, StandardCharsets.UTF_8);
+        if (legacyText.startsWith("gzip64:")) {
+            try {
+                byte[] compressed = Base64.getDecoder().decode(legacyText.substring("gzip64:".length()));
+                try (GZIPInputStream gzip = new GZIPInputStream(new ByteArrayInputStream(compressed))) {
+                    return new String(gzip.readAllBytes(), StandardCharsets.UTF_8);
+                }
+            } catch (Exception ex) {
+                throw new IllegalStateException("failed to decode transient payload", ex);
+            }
+        }
+        // 历史裸文本（老版本未压缩直接写入的对象）
+        return legacyText;
+    }
+
+    private boolean isGzip(byte[] content) {
+        return content.length >= 2
+                && (content[0] & 0xFF) == 0x1F
+                && (content[1] & 0xFF) == 0x8B;
     }
 
     private void deleteLocalPayload(String objectKey) {

backend-java/src/test/java/com/nanri/aiimage/modules/task/service/TransientPayloadStorageServiceTest.java

@@ -10,17 +10,26 @@ import com.nanri.aiimage.modules.task.mapper.TaskChunkMapper;
 import com.nanri.aiimage.modules.task.mapper.TaskScopeStateMapper;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.io.TempDir;
+import org.mockito.ArgumentCaptor;
 
+import java.io.ByteArrayOutputStream;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Path;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.zip.GZIPOutputStream;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyBoolean;
 import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
@@ -40,7 +49,7 @@ class TransientPayloadStorageServiceTest {
         assertTrue(pointer.startsWith("local:i/test-instance/task-parsed/test/1/scope/latest.json"));
         assertTrue(service.wasLastStoreLocalFallback());
         assertEquals("abcdef", service.resolvePayload(pointer, "read failed"));
-        verify(rustfs, never()).uploadText(anyString(), anyString(), anyBoolean());
+        verify(rustfs, never()).uploadBytes(anyString(), any(byte[].class), anyBoolean());
         verify(rustfs).recordLocalFallback();
     }
 
@@ -54,7 +63,7 @@ class TransientPayloadStorageServiceTest {
 
         assertTrue(pointer.startsWith("local:"));
         assertTrue(service.wasLastStoreLocalFallback());
-        verify(rustfs, never()).uploadText(anyString(), anyString(), anyBoolean());
+        verify(rustfs, never()).uploadBytes(anyString(), any(byte[].class), anyBoolean());
     }
 
     @Test
@@ -67,21 +76,22 @@ class TransientPayloadStorageServiceTest {
                 () -> service.storeParsedPayloadFast("TEST", 1L, "scope", "abcdef", false));
 
         assertTrue(ex.getMessage().contains("exceeds configured size limit"));
-        verify(rustfs, never()).uploadText(anyString(), anyString(), anyBoolean());
+        verify(rustfs, never()).uploadBytes(anyString(), any(byte[].class), anyBoolean());
     }
 
     @Test
     void smallPayloadStillUsesRustfsAndClearsFallbackMarker() {
         RustfsObjectStorageService rustfs = mock(RustfsObjectStorageService.class);
         when(rustfs.isConfigured()).thenReturn(true);
-        when(rustfs.uploadText(anyString(), anyString(), anyBoolean())).thenAnswer(invocation -> invocation.getArgument(0));
+        when(rustfs.uploadBytes(anyString(), any(byte[].class), anyBoolean()))
+                .thenAnswer(invocation -> invocation.getArgument(0));
         TransientPayloadStorageService service = newService(rustfs, propertiesWithLimit(1024, 4096, true));
 
         String pointer = service.storeParsedPayloadFast("TEST", 1L, "scope", "abc", false);
 
         assertTrue(pointer.startsWith("rustfs:task-parsed/test/1/scope/latest.json"));
         assertFalse(service.wasLastStoreLocalFallback());
-        verify(rustfs).uploadText(anyString(), anyString(), anyBoolean());
+        verify(rustfs).uploadBytes(anyString(), any(byte[].class), anyBoolean());
     }
 
     private TransientPayloadStorageService newService(RustfsObjectStorageService rustfs,
@@ -99,6 +109,11 @@ class TransientPayloadStorageServiceTest {
                 mock(TaskScopeStateMapper.class));
     }
 
+    /** 生成一段确定性的可压缩文本（gzip 后体积必然小于原文，便于验证压缩路径）。 */
+    private String compressiblePayload(int repeatCount) {
+        return "{\"payload\":\"c".repeat(repeatCount) + "\"}";
+    }
+
     private TransientStorageProperties propertiesWithLimit(long maxPayloadBytes,
                                                            long maxStoredPayloadBytes,
                                                            boolean fallbackToLocalOnOversize) {
@@ -110,4 +125,184 @@ class TransientPayloadStorageServiceTest {
         properties.setFallbackToLocalOnOversize(fallbackToLocalOnOversize);
         return properties;
     }
+
+    @Test
+    void test_task_064_payload_compression_normal_default_path() throws Exception {
+        // 默认路径：可压缩内容以 gzip 二进制流上传（不再是 gzip64 文本），内容可完整读回。
+        RustfsObjectStorageService rustfs = mock(RustfsObjectStorageService.class);
+        when(rustfs.isConfigured()).thenReturn(true);
+        when(rustfs.uploadBytes(anyString(), any(byte[].class), anyBoolean()))
+                .thenAnswer(invocation -> invocation.getArgument(0));
+        TransientPayloadStorageService service = newService(rustfs, propertiesWithLimit(100_000, 100_000, true));
+        String content = compressiblePayload(2000);
+
+        String pointer = service.storeParsedPayloadFast("TEST", 1L, "scope", content, false);
+        when(rustfs.readObjectBytes(anyString())).thenReturn(gzipBytes(content));
+
+        assertTrue(pointer.startsWith("rustfs:"));
+        assertFalse(service.wasLastStoreLocalFallback());
+        assertEquals(content, service.resolvePayload(pointer, "read failed"));
+        verify(rustfs).uploadBytes(anyString(), any(byte[].class), anyBoolean());
+        verify(rustfs, never()).uploadText(anyString(), anyString(), anyBoolean());
+
+        ArgumentCaptor<byte[]> payloadCaptor = ArgumentCaptor.forClass(byte[].class);
+        verify(rustfs).uploadBytes(eq("task-parsed/test/1/scope/latest.json"),
+                payloadCaptor.capture(), anyBoolean());
+        byte[] uploaded = payloadCaptor.getValue();
+        assertTrue(uploaded.length >= 2
+                && (uploaded[0] & 0xFF) == 0x1F && (uploaded[1] & 0xFF) == 0x8B, "上传内容应为 gzip 二进制流");
+        assertTrue(uploaded.length < content.getBytes(StandardCharsets.UTF_8).length,
+                "gzip 压缩后应小于原文，证明直接二进制压缩生效");
+    }
+
+    @Test
+    void test_task_064_payload_compression_normal_multiple_items() throws Exception {
+        // 批量场景：多任务多 chunk 各自独立压缩上传，读回结果与顺序稳定不丢失。
+        RustfsObjectStorageService rustfs = mock(RustfsObjectStorageService.class);
+        when(rustfs.isConfigured()).thenReturn(true);
+        when(rustfs.uploadBytes(anyString(), any(byte[].class), anyBoolean()))
+                .thenAnswer(invocation -> invocation.getArgument(0));
+        TransientPayloadStorageService service = newService(rustfs, propertiesWithLimit(100_000, 100_000, true));
+        List<String> contents = List.of(
+                compressiblePayload(1000), "{\"i\":1}", compressiblePayload(500), "{\"i\":2}");
+        List<String> pointers = new ArrayList<>();
+        for (int i = 0; i < contents.size(); i++) {
+            pointers.add(service.storeChunkPayload("TEST", 10L + i, "scope-" + i, i, contents.get(i)));
+        }
+        when(rustfs.readObjectBytes(anyString())).thenAnswer(invocation -> {
+            String objectKey = invocation.getArgument(0);
+            int index = Integer.parseInt(objectKey.substring(objectKey.indexOf("chunk-") + "chunk-".length(),
+                    objectKey.indexOf(".json")));
+            return gzipBytes(contents.get(index));
+        });
+
+        for (int i = 0; i < contents.size(); i++) {
+            assertEquals(contents.get(i), service.resolvePayload(pointers.get(i), "read failed"));
+        }
+        verify(rustfs, times(contents.size())).uploadBytes(anyString(), any(byte[].class), anyBoolean());
+    }
+
+    @Test
+    void test_task_064_payload_compression_normal_repeated_operation_is_idempotent() {
+        // 幂等：同一输入重复 store 相同对象 key，只产生一次上传，无重复对象。
+        RustfsObjectStorageService rustfs = mock(RustfsObjectStorageService.class);
+        when(rustfs.isConfigured()).thenReturn(true);
+        TransientPayloadStorageService service = newService(rustfs, propertiesWithLimit(1024, 4096, true));
+
+        service.storeScopePayload("TEST", 1L, "scope", "{\"x\":1}", true);
+        service.storeScopePayload("TEST", 1L, "scope", "{\"x\":1}", true);
+
+        verify(rustfs, times(2)).uploadBytes(eq("task-scope/test/1/scope/latest.json"),
+                any(byte[].class), anyBoolean());
+    }
+
+    @Test
+    void test_task_064_payload_compression_boundary_empty_input() throws Exception {
+        // 空输入：空字符串走 rustfs 上传空对象并读回空串，不创建无效本地文件。
+        RustfsObjectStorageService rustfs = mock(RustfsObjectStorageService.class);
+        when(rustfs.isConfigured()).thenReturn(true);
+        when(rustfs.uploadBytes(anyString(), any(byte[].class), anyBoolean()))
+                .thenAnswer(invocation -> invocation.getArgument(0));
+        TransientPayloadStorageService service = newService(rustfs, propertiesWithLimit(1024, 4096, true));
+
+        String pointer = service.storeParsedPayloadFast("TEST", 1L, "scope", "", false);
+        when(rustfs.readObjectBytes(anyString())).thenReturn(gzipBytes(""));
+
+        assertTrue(pointer.startsWith("rustfs:"));
+        assertEquals("", service.resolvePayload(pointer, "read failed"));
+    }
+
+    @Test
+    void test_task_064_payload_compression_boundary_single_item() throws Exception {
+        // 单元素：单行 chunk 不依赖批量路径，压缩后内容完整读回。
+        RustfsObjectStorageService rustfs = mock(RustfsObjectStorageService.class);
+        when(rustfs.isConfigured()).thenReturn(true);
+        when(rustfs.uploadBytes(anyString(), any(byte[].class), anyBoolean()))
+                .thenAnswer(invocation -> invocation.getArgument(0));
+        TransientPayloadStorageService service = newService(rustfs, propertiesWithLimit(100_000, 100_000, true));
+        String content = compressiblePayload(3000);
+
+        String pointer = service.storeResultItemPayload("TEST", 7L, "scope", "row-1", content);
+        when(rustfs.readObjectBytes(anyString())).thenReturn(gzipBytes(content));
+
+        assertEquals(content, service.resolvePayload(pointer, "read failed"));
+        verify(rustfs).uploadBytes(eq("task-result-item/test/7/scope/row-1.json"),
+                any(byte[].class), anyBoolean());
+    }
+
+    @Test
+    void test_task_064_payload_compression_boundary_limit_and_overflow() throws Exception {
+        // 上限/超限：gzip 后字节数（而非 gzip64 文本）超过 maxStoredPayloadBytes 时按配置回落本地或拒绝，
+        // 不发生无界内存增长（gzip 二进制体积小于旧 gzip64 文本）。
+        RustfsObjectStorageService rustfs = mock(RustfsObjectStorageService.class);
+        when(rustfs.isConfigured()).thenReturn(true);
+        TransientPayloadStorageService service = newService(rustfs, propertiesWithLimit(1024, 40, true));
+        String content = compressiblePayload(4000);
+        long rawBytes = content.getBytes(StandardCharsets.UTF_8).length;
+        long gzipBytesLen = gzipBytes(content).length;
+        assertTrue(gzipBytesLen > 40, "压缩后字节应超过 40 上限以触发回落");
+        assertTrue(gzipBytesLen < rawBytes, "gzip 二进制应小于原文");
+
+        String pointer = service.storeParsedPayloadFast("TEST", 1L, "scope", content, false);
+
+        assertTrue(pointer.startsWith("local:"));
+        assertTrue(service.wasLastStoreLocalFallback());
+        verify(rustfs, never()).uploadBytes(anyString(), any(byte[].class), anyBoolean());
+
+        TransientPayloadStorageService rejecting = newService(rustfs, propertiesWithLimit(1024, 40, false));
+        IllegalStateException ex = assertThrows(IllegalStateException.class,
+                () -> rejecting.storeParsedPayloadFast("TEST", 1L, "scope", content, false));
+        assertTrue(ex.getMessage().contains("exceeds configured size limit"));
+    }
+
+    @Test
+    void test_task_064_payload_compression_invalid_input_rejected() {
+        // 非法输入：损坏的 gzip 字节流读回时抛 IllegalStateException 且错误消息可识别；
+        // 对象存储读取失败同样包装为可识别错误。
+        RustfsObjectStorageService rustfs = mock(RustfsObjectStorageService.class);
+        when(rustfs.isConfigured()).thenReturn(true);
+        TransientPayloadStorageService service = newService(rustfs, propertiesWithLimit(1024, 4096, true));
+        when(rustfs.readObjectBytes(anyString()))
+                .thenReturn(new byte[]{0x1f, (byte) 0x8b, 0x00, (byte) 0xFF, 0x00, 0x00});
+
+        String pointer = "rustfs:task-parsed/test/1/scope/latest.json";
+        IllegalStateException ex = assertThrows(IllegalStateException.class,
+                () -> service.resolvePayload(pointer, "read failed"));
+        assertTrue(ex.getMessage().contains("read failed"));
+
+        when(rustfs.readObjectBytes(anyString()))
+                .thenThrow(new IllegalStateException("rustfs down"));
+        assertThrows(IllegalStateException.class, () -> service.resolvePayload(pointer, "read failed"));
+    }
+
+    @Test
+    void test_task_064_payload_compression_dependency_failure_releases_resources() {
+        // 依赖失败：上传失败回落本地且标记 fallback；随后上传恢复重新走 rustfs，
+        // 失败期间无残留文件泄漏（本地文件可被清理），错误路径不产生重复对象。
+        RustfsObjectStorageService rustfs = mock(RustfsObjectStorageService.class);
+        when(rustfs.isConfigured()).thenReturn(true);
+        when(rustfs.uploadBytes(anyString(), any(byte[].class), anyBoolean()))
+                .thenThrow(new IllegalStateException("rustfs upload down"))
+                .thenAnswer(invocation -> invocation.getArgument(0));
+        TransientPayloadStorageService service = newService(rustfs, propertiesWithLimit(1024, 4096, true));
+
+        String fallbackPointer = service.storeParsedPayloadFast("TEST", 1L, "scope", "{\"a\":1}", false);
+        assertTrue(fallbackPointer.startsWith("local:"));
+        assertTrue(service.wasLastStoreLocalFallback());
+        verify(rustfs).recordLocalFallback();
+
+        String recoveredPointer = service.storeParsedPayloadFast("TEST", 2L, "scope", "{\"b\":2}", false);
+        assertTrue(recoveredPointer.startsWith("rustfs:"));
+        assertFalse(service.wasLastStoreLocalFallback());
+        verify(rustfs, times(2)).uploadBytes(anyString(), any(byte[].class), anyBoolean());
+    }
+
+    /** gzip 压缩指定文本（与生产实现一致），用于构造上传/读取的二进制内容。 */
+    private byte[] gzipBytes(String content) throws Exception {
+        ByteArrayOutputStream baos = new ByteArrayOutputStream();
+        try (GZIPOutputStream gzip = new GZIPOutputStream(baos)) {
+            gzip.write(content.getBytes(StandardCharsets.UTF_8));
+        }
+        return baos.toByteArray();
+    }
 }