test(sdk): 覆盖 endpoint/template 实例 get 的 _config fallback 分支

之前在 fix(sdk): 修复方法级 config 在调用链中被悄悄丢弃中给
AgentRuntimeEndpoint.get 与 Template.get 的实例方法补了
config ?? this._config fallback，但没有相应的测试覆盖两个分支，
导致 agent-runtime 分支覆盖率从 ≥95% 跌到 93.64%、sandbox 跌到
90%，未能通过覆盖率门禁。

补两组等价的 case 分别命中两个分支:

- tests/unittests/agent-runtime/agent-runtime.test.ts: 新增
  describe('get (instance)')，分别验证 endpoint.get({ config })
  时透传 params.config，以及 endpoint.get() 时回落到构造时传入的
  instance _config
- tests/unittests/sandbox/template.test.ts: 同构地为 Template
  实例 get 增加 params.config 与 _config fallback 两个 case

补完后覆盖率：agent-runtime 分支 95.45%、sandbox 分支 100%、全量
分支 97.37%，重新跨过 95% 门槛。

Change-Id: I61ddc203253722378e83abe4eef639932bda8b64
Co-developed-by: Claude <noreply@anthropic.com>
Signed-off-by: OhYee <oyohyee@oyohyee.com>

Author: OhYee

tests/unittests/agent-runtime/agent-runtime.test.ts

@@ -1568,6 +1568,55 @@ describe('Agent Runtime Module', () => {
         });
       });
 
+      describe('get (instance)', () => {
+        it('should fetch using params.config when provided', async () => {
+          mockControlApi.getAgentRuntimeEndpoint.mockResolvedValue({
+            agentRuntimeEndpointId: 'endpoint-123',
+            agentRuntimeEndpointName: 'test-endpoint',
+            status: 'READY',
+          });
+
+          const instanceConfig = new Config({ accountId: 'instance-acc' });
+          const callConfig = new Config({ accountId: 'call-acc' });
+
+          const endpoint = new AgentRuntimeEndpoint(
+            {
+              agentRuntimeId: 'runtime-123',
+              agentRuntimeEndpointId: 'endpoint-123',
+            },
+            instanceConfig
+          );
+
+          await endpoint.get({ config: callConfig });
+
+          expect(mockControlApi.getAgentRuntimeEndpoint).toHaveBeenCalledWith(
+            expect.objectContaining({ config: callConfig })
+          );
+        });
+
+        it('should fall back to instance _config when params.config is missing', async () => {
+          mockControlApi.getAgentRuntimeEndpoint.mockResolvedValue({
+            agentRuntimeEndpointId: 'endpoint-123',
+          });
+
+          const instanceConfig = new Config({ accountId: 'instance-acc' });
+
+          const endpoint = new AgentRuntimeEndpoint(
+            {
+              agentRuntimeId: 'runtime-123',
+              agentRuntimeEndpointId: 'endpoint-123',
+            },
+            instanceConfig
+          );
+
+          await endpoint.get();
+
+          expect(mockControlApi.getAgentRuntimeEndpoint).toHaveBeenCalledWith(
+            expect.objectContaining({ config: instanceConfig })
+          );
+        });
+      });
+
       describe('waitUntilReady', () => {
         it('should wait until status is READY', async () => {
           let callCount = 0;

tests/unittests/sandbox/template.test.ts

@@ -725,6 +725,44 @@ describe('Template', () => {
       });
     });
 
+    describe('get (instance)', () => {
+      // eslint-disable-next-line @typescript-eslint/no-var-requires
+      const { Config } = require('../../../src/utils/config');
+
+      it('should fetch using params.config when provided', async () => {
+        mockClientGetTemplate.mockResolvedValue({
+          templateId: 'template-123',
+          templateName: 'test-template',
+        });
+
+        const instanceConfig = new Config({ accountId: 'instance-acc' });
+        const callConfig = new Config({ accountId: 'call-acc' });
+
+        const template = new Template({ templateName: 'test-template' }, instanceConfig);
+        await template.get({ config: callConfig });
+
+        expect(mockClientGetTemplate).toHaveBeenCalledWith(
+          expect.objectContaining({ config: callConfig })
+        );
+      });
+
+      it('should fall back to instance _config when params.config is missing', async () => {
+        mockClientGetTemplate.mockResolvedValue({
+          templateId: 'template-123',
+          templateName: 'test-template',
+        });
+
+        const instanceConfig = new Config({ accountId: 'instance-acc' });
+        const template = new Template({ templateName: 'test-template' }, instanceConfig);
+
+        await template.get();
+
+        expect(mockClientGetTemplate).toHaveBeenCalledWith(
+          expect.objectContaining({ config: instanceConfig })
+        );
+      });
+    });
+
     describe('waitUntilReady', () => {
       it('should return immediately if already ready', async () => {
         mockClientGetTemplate.mockResolvedValue({