diff --git a/integration-tests/cli/qwen-config-dir.test.ts b/integration-tests/cli/qwen-config-dir.test.ts
index 47b2cee736..aa7268f423 100644
--- a/integration-tests/cli/qwen-config-dir.test.ts
+++ b/integration-tests/cli/qwen-config-dir.test.ts
@@ -57,6 +57,7 @@ describe('QWEN_HOME environment variable', () => {
     // Always clean up env vars regardless of test outcome
     delete process.env['QWEN_HOME'];
     delete process.env['QWEN_RUNTIME_DIR'];
+    delete process.env['QWEN_DEBUG_LOG_FILE'];
     await rig.cleanup();
   });
 
@@ -324,6 +325,7 @@ describe('QWEN_HOME environment variable', () => {
 
       process.env['QWEN_HOME'] = customConfigDir;
       process.env['QWEN_RUNTIME_DIR'] = runtimeDir;
+      process.env['QWEN_DEBUG_LOG_FILE'] = '1';
 
       try {
         await rig.run('say hello');
diff --git a/integration-tests/cli/simple-mcp-server.test.ts b/integration-tests/cli/simple-mcp-server.test.ts
index 7e6710a450..cbdd36b19c 100644
--- a/integration-tests/cli/simple-mcp-server.test.ts
+++ b/integration-tests/cli/simple-mcp-server.test.ts
@@ -169,6 +169,7 @@ rpc.send({
 
 describe('simple-mcp-server', () => {
   const rig = new TestRig();
+  let previousLegacyMcpBlocking: string | undefined;
   let previousMcpApprovalsPath: string | undefined;
 
   beforeAll(async () => {
@@ -177,6 +178,7 @@ describe('simple-mcp-server', () => {
     // request fires without the MCP `add` tool wired into the model's tool
     // surface, so the model answers `15` directly and `foundToolCall` stays
     // false. Remove once QwenLM/qwen-code#4163 is fixed.
+    previousLegacyMcpBlocking = process.env['QWEN_CODE_LEGACY_MCP_BLOCKING'];
     process.env['QWEN_CODE_LEGACY_MCP_BLOCKING'] = '1';
 
     // Setup test directory with MCP server configuration
@@ -238,6 +240,12 @@ describe('simple-mcp-server', () => {
   });
 
   afterAll(() => {
+    if (previousLegacyMcpBlocking === undefined) {
+      delete process.env['QWEN_CODE_LEGACY_MCP_BLOCKING'];
+    } else {
+      process.env['QWEN_CODE_LEGACY_MCP_BLOCKING'] = previousLegacyMcpBlocking;
+    }
+
     if (previousMcpApprovalsPath === undefined) {
       delete process.env['QWEN_CODE_MCP_APPROVALS_PATH'];
     } else {
diff --git a/packages/cli/src/utils/sandbox.ts b/packages/cli/src/utils/sandbox.ts
index 477dd91995..5cabed9f19 100644
--- a/packages/cli/src/utils/sandbox.ts
+++ b/packages/cli/src/utils/sandbox.ts
@@ -634,6 +634,22 @@ export async function start_sandbox(
       `QWEN_CODE_TEST_VAR=${process.env['QWEN_CODE_TEST_VAR']}`,
     );
   }
+  for (const envVar of [
+    'QWEN_DEBUG_LOG_FILE',
+    'QWEN_CODE_LEGACY_MCP_BLOCKING',
+  ] as const) {
+    if (process.env[envVar]) {
+      args.push('--env', `${envVar}=${process.env[envVar]}`);
+    }
+  }
+  if (process.env['QWEN_CODE_MCP_APPROVALS_PATH']) {
+    args.push(
+      '--env',
+      `QWEN_CODE_MCP_APPROVALS_PATH=${getContainerPath(
+        process.env['QWEN_CODE_MCP_APPROVALS_PATH'],
+      )}`,
+    );
+  }
 
   // copy GEMINI_API_KEY(s)
   if (process.env['GEMINI_API_KEY']) {