diff --git a/.data/attachments/inbound/rfq-20260727Z@x.com.eml b/.data/attachments/inbound/rfq-20260727Z@x.com.eml
new file mode 100644
index 0000000..96fa7b8
--- /dev/null
+++ b/.data/attachments/inbound/rfq-20260727Z@x.com.eml
@@ -0,0 +1,12 @@
+{
+  "messageId": "rfq-20260727Z@x.com",
+  "from": "buyer@x.com",
+  "to": [
+    "rfq@we.com"
+  ],
+  "cc": [],
+  "subject": "【询价】客户 C200 RFQ-20260727Z 求报价",
+  "body": "客户编码 C200,询价单号 RFQ-��\nPN-FULL-001 TI 年用量 9000 目标价 6.00 交期 10w",
+  "receivedAt": "2026-07-27T20:00:00.000Z",
+  "attachments": []
+}
\ No newline at end of file
diff --git a/apps/api/src/modules/flow-engine/__tests__/step-sequence.test.ts b/apps/api/src/modules/flow-engine/__tests__/step-sequence.test.ts
index 2ca9e76..3ca5b2b 100644
--- a/apps/api/src/modules/flow-engine/__tests__/step-sequence.test.ts
+++ b/apps/api/src/modules/flow-engine/__tests__/step-sequence.test.ts
@@ -32,6 +32,28 @@ describe('人兜底:出参契约属于步,不属于执行者', () => {
     expect(fallbackFields(llmStep())).toEqual(['pn', 'brand', 'eau']);
   });
 
+  it('行标识也要问 —— 主键取不到就写不进台账', () => {
+    const step = flowStepSchema.parse({
+      kind: 'llm',
+      name: 'S1',
+      label: '生成正式报价单',
+      input: {},
+      model: 'm',
+      template: 't',
+      outputSchema: { type: 'object' },
+      output: {
+        domain: 'q',
+        object: 'formal_quote',
+        key: { quote_no: 'quoteNo', pn: 'pn' },
+        fields: { unit_price: 'unitPrice' },
+      },
+      failure: { retry: { times: 0, backoff: 'PT1S' }, fallback: { kind: 'human', workOrder: 'execution' } },
+    });
+    // pn 上游已给,不必再问;quoteNo 没人给过,必须问
+    expect(fallbackFields(step, { pn: 'LM358DR' })).toEqual(['quoteNo', 'unitPrice']);
+    expect(fallbackFields(step, {})).toEqual(['quoteNo', 'pn', 'unitPrice']);
+  });
+
   it('无出参声明的步不凭空造字段', () => {
     const step = flowStepSchema.parse({
       kind: 'llm',
diff --git a/apps/api/src/modules/flow-engine/internal/domain/step-sequence.ts b/apps/api/src/modules/flow-engine/internal/domain/step-sequence.ts
index bef86ae..18eadb5 100644
--- a/apps/api/src/modules/flow-engine/internal/domain/step-sequence.ts
+++ b/apps/api/src/modules/flow-engine/internal/domain/step-sequence.ts
@@ -133,8 +133,12 @@ export function parallelGroupComplete(position: FlowPosition, members: readonly
  *
  * 返回键名数组,与 human 步的 `card.fields` 同形:卡的渲染只有一套。
  */
-export function fallbackFields(step: FlowStep): readonly string[] {
-  return step.output === undefined ? [] : Object.values(step.output.fields);
+export function fallbackFields(step: FlowStep, scope: Readonly<Record<string, unknown>> = {}): readonly string[] {
+  if (step.output === undefined) return [];
+  // 出参的值要问,**行标识**也要问 —— 主键取不到就写不进台账(非空约束会在合并时挡下)。
+  // 作用域里已经有的键不必再问一遍:上游给过就是给过了。
+  const keys = Object.values(step.output.key).filter((path) => scope[path] === undefined);
+  return [...new Set([...keys, ...Object.values(step.output.fields)])];
 }
 
 /**
diff --git a/apps/api/src/modules/flow-engine/internal/usecase/flow-runner.ts b/apps/api/src/modules/flow-engine/internal/usecase/flow-runner.ts
index 6610196..0fc9cd2 100644
--- a/apps/api/src/modules/flow-engine/internal/usecase/flow-runner.ts
+++ b/apps/api/src/modules/flow-engine/internal/usecase/flow-runner.ts
@@ -210,7 +210,7 @@ export function createFlowRunner(deps: FlowRunnerDeps): FlowEngineService {
           reason: error,
           // 兜底的人要交的东西,和这一步**本来该产出的东西**同形:
           // 出参契约是步的契约,不因换谁来做而变(统一执行契约)。
-          fields: fallbackFields(step),
+          fields: fallbackFields(step, await deps.data.view(taskId)),
         },
       });
       await deps.listeners.register({