diff --git a/.env-example b/.env-example
index 219a1c40..aacdfcbe 100644
--- a/.env-example
+++ b/.env-example
@@ -8,9 +8,9 @@
 AI_LIVE_PRIMARY_MODEL_NAME=gpt-5.4-mini
 AI_LIVE_VISUAL_MODEL_NAME=qwen3.6-plus
 
-# LangSmith tracing（仅开发环境主进程读取）
-LANGSMITH_TRACING=true
+# LangSmith tracing（默认关闭；排查时手动改为 true）
+LANGSMITH_TRACING=false
 LANGSMITH_ENDPOINT=https://api.smith.langchain.com
 LANGSMITH_PROJECT=ncurator
-LANGSMITH_API_KEY=REMOVED_HISTORICAL_KEY
+LANGSMITH_API_KEY=
 LANGCHAIN_CALLBACKS_BACKGROUND=true
diff --git a/doc/test.md b/doc/test.md
index ec7762d9..f169fba8 100644
--- a/doc/test.md
+++ b/doc/test.md
@@ -90,6 +90,7 @@ tests/
 - `ai-test` 专门覆盖 AI 架构及其工具，全部是 backend；`settings-test` 和 `workbench-test` 专门覆盖对应 PRD 功能点，全部是 E2E；Unit 只补足前述范围未覆盖的 backend 函数、类和底层逻辑。
 - `scripts/test/validate-test-architecture.mjs` 在 runner 执行前校验域边界、Unit 禁止项、计划必填字段、PRD 引用、case/runner 包装和目录映射。
 - `scripts/test/workflow.mjs` 会自动读取仓库根目录的 `.env.local`、`.env`（已存在的 shell 环境变量优先）；可用 `AI_TEST_DISABLE_DOTENV=1` 禁用自动加载。
+- LangSmith tracing 默认关闭；仅在排查时将 `LANGSMITH_TRACING=true`，结束后恢复为 `false`。
 
 ### 3.3 UI E2E 回归规则
 
diff --git a/tests/case/unit/release/app-update-publish-config.test.ts b/tests/case/unit/release/app-update-publish-config.test.ts
index 31ac3d1b..bbebcd0d 100644
--- a/tests/case/unit/release/app-update-publish-config.test.ts
+++ b/tests/case/unit/release/app-update-publish-config.test.ts
@@ -125,4 +125,11 @@ describe('app update publish config', () => {
     expect(architectureValidator).toContain('warmupFiles.length !== 1')
     expect(warmupCase).toContain("execution: 'warmup'")
   })
+
+  it('keeps LangSmith tracing opt-in by default', async () => {
+    const exampleEnv = await readFile(path.resolve('.env-example'), 'utf8')
+
+    expect(exampleEnv).toMatch(/^LANGSMITH_TRACING=false$/mu)
+    expect(exampleEnv).toMatch(/^LANGSMITH_API_KEY=$/mu)
+  })
 })