diff --git a/testkit/src/main/java/apelet/common/ecommerce/testkit/FakeTransport.java b/testkit/src/main/java/apelet/common/ecommerce/testkit/FakeTransport.java
new file mode 100644
index 0000000..2509437
--- /dev/null
+++ b/testkit/src/main/java/apelet/common/ecommerce/testkit/FakeTransport.java
@@ -0,0 +1,85 @@
+package apelet.common.ecommerce.testkit;
+
+import apelet.common.ecommerce.http.HttpRequest;
+import apelet.common.ecommerce.http.HttpResponse;
+import apelet.common.ecommerce.http.HttpTransport;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.function.Function;
+
+/**
+ * 可编程传输。适配器单测直接返回录制的响应，不需要网络或 mock server。
+ *
+ * <pre>
+ * FakeTransport t = FakeTransport.create()
+ *     .route("lingxing", "order/v2/list", body -&gt; HttpResponse.of(200, null, json, 5));
+ * </pre>
+ */
+public final class FakeTransport implements HttpTransport {
+
+    private final List<HttpRequest> recorded = new ArrayList<HttpRequest>();
+    private final List<Route> routes = new ArrayList<Route>();
+    private Function<HttpRequest, HttpResponse> fallback;
+
+    public static FakeTransport create() {
+        return new FakeTransport();
+    }
+
+    /** 按 URL 子串 + 方法匹配。 */
+    public FakeTransport route(String urlContains, String method, Function<HttpRequest, HttpResponse> responder) {
+        routes.add(new Route(urlContains, method, responder));
+        return this;
+    }
+
+    public FakeTransport route(String urlContains, Function<HttpRequest, HttpResponse> responder) {
+        return route(urlContains, null, responder);
+    }
+
+    public FakeTransport fallback(Function<HttpRequest, HttpResponse> responder) {
+        this.fallback = responder;
+        return this;
+    }
+
+    @Override
+    public HttpResponse execute(HttpRequest request) {
+        recorded.add(request);
+        for (Route r : routes) {
+            if (request.url().contains(r.urlContains)
+                    && (r.method == null || r.method.equalsIgnoreCase(request.method()))) {
+                return r.responder.apply(request);
+            }
+        }
+        if (fallback != null) {
+            return fallback.apply(request);
+        }
+        throw new IllegalStateException("no fake route for " + request.method() + " " + request.url());
+    }
+
+    public List<HttpRequest> recorded() {
+        return Collections.unmodifiableList(recorded);
+    }
+
+    /** 最后一次请求；无请求时返回 null。 */
+    public HttpRequest lastRequest() {
+        return recorded.isEmpty() ? null : recorded.get(recorded.size() - 1);
+    }
+
+    public void clear() {
+        recorded.clear();
+    }
+
+    private static final class Route {
+
+        private final String urlContains;
+        private final String method;
+        private final Function<HttpRequest, HttpResponse> responder;
+
+        private Route(String urlContains, String method, Function<HttpRequest, HttpResponse> responder) {
+            this.urlContains = urlContains;
+            this.method = method;
+            this.responder = responder;
+        }
+    }
+}
diff --git a/testkit/src/main/java/apelet/common/ecommerce/testkit/Fixtures.java b/testkit/src/main/java/apelet/common/ecommerce/testkit/Fixtures.java
new file mode 100644
index 0000000..994fc59
--- /dev/null
+++ b/testkit/src/main/java/apelet/common/ecommerce/testkit/Fixtures.java
@@ -0,0 +1,36 @@
+package apelet.common.ecommerce.testkit;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.charset.StandardCharsets;
+import java.util.Scanner;
+
+/**
+ * 夹具加载器。
+ *
+ * <p>约定目录：{@code src/test/resources/fixtures/{platform}/{operation}/{case}.json}。
+ * 适配器测试只依赖录制报文，不依赖网络。</p>
+ */
+public final class Fixtures {
+
+    private Fixtures() {
+    }
+
+    public static String load(Class<?> anchor, String path) {
+        String resource = path.startsWith("/") ? path : "/" + path;
+        try (InputStream in = anchor.getResourceAsStream(resource)) {
+            if (in == null) {
+                throw new IllegalStateException("fixture not found: " + resource);
+            }
+            Scanner scanner = new Scanner(in, StandardCharsets.UTF_8.name()).useDelimiter("\\A");
+            return scanner.hasNext() ? scanner.next() : "";
+        } catch (IOException e) {
+            throw new IllegalStateException("read fixture failed: " + resource, e);
+        }
+    }
+
+    /** 按约定拼路径。 */
+    public static String load(Class<?> anchor, String platform, String operation, String caseName) {
+        return load(anchor, "fixtures/" + platform + "/" + operation + "/" + caseName + ".json");
+    }
+}
diff --git a/testkit/src/main/java/apelet/common/ecommerce/testkit/InMemoryAccounts.java b/testkit/src/main/java/apelet/common/ecommerce/testkit/InMemoryAccounts.java
new file mode 100644
index 0000000..a18b85d
--- /dev/null
+++ b/testkit/src/main/java/apelet/common/ecommerce/testkit/InMemoryAccounts.java
@@ -0,0 +1,59 @@
+package apelet.common.ecommerce.testkit;
+
+import apelet.common.ecommerce.spi.ChannelAccountRepository;
+import apelet.common.ecommerce.spi.ChannelSecret;
+import apelet.common.ecommerce.model.ChannelAccount;
+import apelet.common.ecommerce.spi.SecretProvider;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+
+/** 内存版账户仓库与凭证提供者。 */
+public final class InMemoryAccounts implements ChannelAccountRepository, SecretProvider {
+
+    private final Map<String, ChannelAccount> accounts = new HashMap<String, ChannelAccount>();
+    private final Map<String, ChannelSecret> secrets = new HashMap<String, ChannelSecret>();
+
+    public InMemoryAccounts put(ChannelAccount account) {
+        accounts.put(id(account.provider().name(), account.platform().name(), account.omsStoreId()), account);
+        return this;
+    }
+
+    public InMemoryAccounts putSecret(String credentialRef, ChannelSecret secret) {
+        secrets.put(credentialRef, secret);
+        return this;
+    }
+
+    @Override
+    public Optional<ChannelAccount> findByKey(String provider, String platform, String omsStoreId) {
+        return Optional.ofNullable(accounts.get(id(provider, platform, omsStoreId)));
+    }
+
+    @Override
+    public List<ChannelAccount> findByOmsStoreId(String omsStoreId) {
+        List<ChannelAccount> out = new ArrayList<ChannelAccount>();
+        for (ChannelAccount a : accounts.values()) {
+            if (a.omsStoreId().equals(omsStoreId)) {
+                out.add(a);
+            }
+        }
+        return Collections.unmodifiableList(out);
+    }
+
+    @Override
+    public ChannelSecret get(String credentialRef) {
+        ChannelSecret s = secrets.get(credentialRef);
+        if (s == null) {
+            throw new IllegalStateException("no fake secret for " + credentialRef);
+        }
+        return s;
+    }
+
+    private static String id(String provider, String platform, String omsStoreId) {
+        return provider + '|' + platform + '|' + omsStoreId;
+    }
+}
diff --git a/testkit/src/main/java/apelet/common/ecommerce/testkit/InMemoryCursorStore.java b/testkit/src/main/java/apelet/common/ecommerce/testkit/InMemoryCursorStore.java
new file mode 100644
index 0000000..d9f2028
--- /dev/null
+++ b/testkit/src/main/java/apelet/common/ecommerce/testkit/InMemoryCursorStore.java
@@ -0,0 +1,37 @@
+package apelet.common.ecommerce.testkit;
+
+import apelet.common.ecommerce.model.ChannelProvider;
+import apelet.common.ecommerce.spi.SyncCursorStore;
+
+import java.time.Instant;
+import java.util.HashMap;
+import java.util.Map;
+
+/** 内存版水位线存储。 */
+public final class InMemoryCursorStore implements SyncCursorStore {
+
+    private final Map<String, Instant> cursors = new HashMap<String, Instant>();
+
+    @Override
+    public Instant get(ChannelProvider provider, String accountKey, String stream) {
+        return cursors.get(id(provider, accountKey, stream));
+    }
+
+    @Override
+    public void advance(ChannelProvider provider, String accountKey, String stream, Instant watermark) {
+        cursors.put(id(provider, accountKey, stream), watermark);
+    }
+
+    public void seed(ChannelProvider provider, String accountKey, String stream, Instant watermark) {
+        advance(provider, accountKey, stream, watermark);
+    }
+
+    /** 断言用：读取当前水位线。 */
+    public Instant watermark(ChannelProvider provider, String accountKey, String stream) {
+        return get(provider, accountKey, stream);
+    }
+
+    private static String id(ChannelProvider provider, String accountKey, String stream) {
+        return provider.name() + '|' + accountKey + '|' + stream;
+    }
+}
diff --git a/testkit/src/main/java/apelet/common/ecommerce/testkit/InMemoryLockProvider.java b/testkit/src/main/java/apelet/common/ecommerce/testkit/InMemoryLockProvider.java
new file mode 100644
index 0000000..fa67ed0
--- /dev/null
+++ b/testkit/src/main/java/apelet/common/ecommerce/testkit/InMemoryLockProvider.java
@@ -0,0 +1,52 @@
+package apelet.common.ecommerce.testkit;
+
+import apelet.common.ecommerce.spi.LockProvider;
+
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+
+/** 单线程内存锁，足以验证防击穿分支。 */
+public final class InMemoryLockProvider implements LockProvider {
+
+    private final Set<String> held = new HashSet<String>();
+    private final Map<String, Integer> acquireCounts = new HashMap<String, Integer>();
+
+    @Override
+    public synchronized Optional<Lock> tryLock(String key, long ttlSeconds) {
+        if (held.contains(key)) {
+            return Optional.empty();
+        }
+        held.add(key);
+        Integer c = acquireCounts.get(key);
+        acquireCounts.put(key, c == null ? 1 : c + 1);
+        return Optional.<Lock>of(new Handle(key));
+    }
+
+    public synchronized int acquireCount(String key) {
+        Integer c = acquireCounts.get(key);
+        return c == null ? 0 : c;
+    }
+
+    public synchronized boolean isHeld(String key) {
+        return held.contains(key);
+    }
+
+    private final class Handle implements Lock {
+
+        private final String key;
+
+        private Handle(String key) {
+            this.key = key;
+        }
+
+        @Override
+        public void close() {
+            synchronized (InMemoryLockProvider.this) {
+                held.remove(key);
+            }
+        }
+    }
+}
diff --git a/testkit/src/main/java/apelet/common/ecommerce/testkit/InMemorySink.java b/testkit/src/main/java/apelet/common/ecommerce/testkit/InMemorySink.java
new file mode 100644
index 0000000..5431ddd
--- /dev/null
+++ b/testkit/src/main/java/apelet/common/ecommerce/testkit/InMemorySink.java
@@ -0,0 +1,47 @@
+package apelet.common.ecommerce.testkit;
+
+import apelet.common.ecommerce.model.Page;
+import apelet.common.ecommerce.model.ProductListing;
+import apelet.common.ecommerce.model.SalesOrder;
+import apelet.common.ecommerce.spi.Sink;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+/** 内存版落库 Sink，记录每次 upsert。 */
+public final class InMemorySink implements Sink {
+
+    private final List<SalesOrder> salesOrders = new ArrayList<SalesOrder>();
+    private final List<ProductListing> products = new ArrayList<ProductListing>();
+    private int salesOrderUpsertCalls;
+    private int productUpsertCalls;
+
+    @Override
+    public void upsertSalesOrders(Page<SalesOrder> page) {
+        salesOrders.addAll(page.items());
+        salesOrderUpsertCalls++;
+    }
+
+    @Override
+    public void upsertProducts(Page<ProductListing> page) {
+        products.addAll(page.items());
+        productUpsertCalls++;
+    }
+
+    public List<SalesOrder> salesOrders() {
+        return Collections.unmodifiableList(salesOrders);
+    }
+
+    public List<ProductListing> products() {
+        return Collections.unmodifiableList(products);
+    }
+
+    public int salesOrderUpsertCalls() {
+        return salesOrderUpsertCalls;
+    }
+
+    public int productUpsertCalls() {
+        return productUpsertCalls;
+    }
+}
diff --git a/testkit/src/main/java/apelet/common/ecommerce/testkit/InMemoryTokenStore.java b/testkit/src/main/java/apelet/common/ecommerce/testkit/InMemoryTokenStore.java
new file mode 100644
index 0000000..3262c23
--- /dev/null
+++ b/testkit/src/main/java/apelet/common/ecommerce/testkit/InMemoryTokenStore.java
@@ -0,0 +1,36 @@
+package apelet.common.ecommerce.testkit;
+
+import apelet.common.ecommerce.spi.AccessToken;
+import apelet.common.ecommerce.spi.TokenStore;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Optional;
+
+/** 内存版令牌存储。 */
+public final class InMemoryTokenStore implements TokenStore {
+
+    private final Map<String, AccessToken> tokens = new HashMap<String, AccessToken>();
+    private int saveCount;
+
+    @Override
+    public Optional<AccessToken> get(String tokenKey) {
+        return Optional.ofNullable(tokens.get(tokenKey));
+    }
+
+    @Override
+    public void save(String tokenKey, AccessToken token) {
+        tokens.put(tokenKey, token);
+        saveCount++;
+    }
+
+    @Override
+    public void remove(String tokenKey) {
+        tokens.remove(tokenKey);
+    }
+
+    /** 刷新写入次数，用于断言「防击穿只刷新一次」。 */
+    public int saveCount() {
+        return saveCount;
+    }
+}
diff --git a/testkit/src/main/java/apelet/common/ecommerce/testkit/Responses.java b/testkit/src/main/java/apelet/common/ecommerce/testkit/Responses.java
new file mode 100644
index 0000000..242383c
--- /dev/null
+++ b/testkit/src/main/java/apelet/common/ecommerce/testkit/Responses.java
@@ -0,0 +1,25 @@
+package apelet.common.ecommerce.testkit;
+
+import apelet.common.ecommerce.http.HttpResponse;
+
+import java.util.Collections;
+
+/** 快捷构造响应。 */
+public final class Responses {
+
+    private Responses() {
+    }
+
+    public static HttpResponse ok(String body) {
+        return HttpResponse.of(200, Collections.<String, String>emptyMap(), body, 1);
+    }
+
+    public static HttpResponse status(int code, String body) {
+        return HttpResponse.of(code, Collections.<String, String>emptyMap(), body, 1);
+    }
+
+    public static HttpResponse rateLimited(String retryAfterSeconds) {
+        return HttpResponse.of(429,
+                Collections.singletonMap("Retry-After", retryAfterSeconds), "", 1);
+    }
+}
diff --git a/testkit/src/main/java/apelet/common/ecommerce/testkit/TestData.java b/testkit/src/main/java/apelet/common/ecommerce/testkit/TestData.java
new file mode 100644
index 0000000..832271e
--- /dev/null
+++ b/testkit/src/main/java/apelet/common/ecommerce/testkit/TestData.java
@@ -0,0 +1,32 @@
+package apelet.common.ecommerce.testkit;
+
+import apelet.common.ecommerce.model.Page;
+import apelet.common.ecommerce.model.SalesOrder;
+import apelet.common.ecommerce.spi.SyncCursorStore;
+
+import java.time.Duration;
+import java.time.Instant;
+
+/** 测试夹具：常用账户与同步维度。 */
+public final class TestData {
+
+    private TestData() {
+    }
+
+    public static Instant utc(String iso) {
+        return Instant.parse(iso);
+    }
+
+    public static Duration overlapMinutes(int minutes) {
+        return Duration.ofMinutes(minutes);
+    }
+
+    /** 已推进过的水位线，避免测试里每次走全量。 */
+    public static void seedWatermark(SyncCursorStore store, apelet.common.ecommerce.sync.SyncSpec spec, String iso) {
+        store.advance(spec.provider(), spec.accountKey(), spec.stream(), Instant.parse(iso));
+    }
+
+    public static Page<SalesOrder> pageOf(SalesOrder... orders) {
+        return Page.last(java.util.Arrays.asList(orders));
+    }
+}