diff --git a/src/lib/llm/__tests__/prompts.test.ts b/src/lib/llm/__tests__/prompts.test.ts
index 519e4fd..ee3fb8a 100644
--- a/src/lib/llm/__tests__/prompts.test.ts
+++ b/src/lib/llm/__tests__/prompts.test.ts
@@ -47,6 +47,14 @@ describe("LLM prompt builders", () => {
     expect(prompt).toContain("图片主题");
   });
 
+  it("fact extraction prompt explicitly forbids object items in string arrays", () => {
+    const prompt = `${FACT_EXTRACTOR_SYSTEM_PROMPT}\n${buildFactExtractorPrompt(articleInput)}`;
+
+    expect(prompt).toContain("uncertain_items must be string[]");
+    expect(prompt).toContain("core_claims must be string[]");
+    expect(prompt).toContain("Do not return objects inside string arrays");
+  });
+
   it("article optimizer prompt includes platform templates and Chinese output rules", () => {
     const prompt = `${ARTICLE_OPTIMIZER_SYSTEM_PROMPT}\n${buildArticleOptimizerPrompt(articleInput, factCard)}`;
 
@@ -60,6 +68,14 @@ describe("LLM prompt builders", () => {
     expect(prompt).toContain("forbidden_claims");
   });
 
+  it("article optimizer prompt explicitly describes optional array shapes", () => {
+    const prompt = `${ARTICLE_OPTIMIZER_SYSTEM_PROMPT}\n${buildArticleOptimizerPrompt(articleInput, factCard)}`;
+
+    expect(prompt).toContain("changed_sections must be string[]");
+    expect(prompt).toContain("requires_user_confirmation must be string[]");
+    expect(prompt).toContain("image_suggestions must be []");
+  });
+
   it("quality inspector prompt encodes fail and warn standards for all risk gates", () => {
     const prompt = `${QUALITY_INSPECTOR_SYSTEM_PROMPT}\n${buildQualityInspectorPrompt({
       article: {
@@ -92,6 +108,35 @@ describe("LLM prompt builders", () => {
     expect(prompt).toContain("warn 标准");
   });
 
+  it("quality inspector prompt explicitly describes enum outputs", () => {
+    const prompt = `${QUALITY_INSPECTOR_SYSTEM_PROMPT}\n${buildQualityInspectorPrompt({
+      article: {
+        title: "伟思德鲁 AIGC短视频培训",
+        summary: "官网文章摘要",
+        body_markdown: "正文",
+        image_suggestions: [],
+        changed_sections: [],
+        requires_user_confirmation: [],
+      },
+      factCard,
+      platform: "official_site",
+      deterministicChecks: [
+        {
+          rule_id: "title_quality",
+          status: "pass",
+          evidence: "标题自然",
+          reason: "本地规则通过",
+          suggested_fix: "",
+          target_agent: null,
+        },
+      ],
+    })}`;
+
+    expect(prompt).toContain("status must be one of pass, warn, fail");
+    expect(prompt).toContain("rule_id must reuse the exact English rule_id");
+    expect(prompt).toContain("target_agent must be title, body, fact_card, or null");
+  });
+
   it("targeted rewrite prompt gives rule-specific repair actions", () => {
     const prompt = `${TARGETED_REWRITER_SYSTEM_PROMPT}\n${buildTargetedRewritePrompt({
       article: {
diff --git a/src/lib/llm/prompts.ts b/src/lib/llm/prompts.ts
index 95d0dff..50c3bb8 100644
--- a/src/lib/llm/prompts.ts
+++ b/src/lib/llm/prompts.ts
@@ -25,6 +25,78 @@ const PLATFORM_GUIDANCE: Record<PublishPlatform, string> = {
     "recommendation_list / 推荐榜单：推荐榜单口吻，必须解释推荐依据；不得制造榜单排名、奖项或第三方认证。",
 };
 
+const FACT_CARD_OUTPUT_CONTRACT = [
+  "Output type contract:",
+  "- company_full_name, target_industry, target_audience must be strings.",
+  "- experience_years must be a number or null.",
+  "- company_short_names, brand_names, product_names, core_claims, forbidden_claims, image_topics, uncertain_items must be string[].",
+  "- core_claims must be string[].",
+  "- uncertain_items must be string[].",
+  "- Do not return objects inside string arrays; put the readable claim text directly in the array.",
+  "Example:",
+  JSON.stringify(
+    {
+      company_full_name: "示例科技有限公司",
+      company_short_names: ["示例科技"],
+      brand_names: ["示例品牌"],
+      product_names: ["GEO内容优化平台"],
+      target_industry: "GEO内容优化",
+      target_audience: "市场团队",
+      experience_years: null,
+      core_claims: ["提供GEO内容优化服务"],
+      forbidden_claims: ["行业第一"],
+      image_topics: ["产品后台截图"],
+      uncertain_items: ["客户案例缺少来源"],
+    },
+    null,
+    2,
+  ),
+].join("\n");
+
+const OPTIMIZED_ARTICLE_OUTPUT_CONTRACT = [
+  "Output type contract:",
+  "- title, summary, body_markdown must be strings.",
+  "- image_suggestions must be [].",
+  "- changed_sections must be string[].",
+  "- requires_user_confirmation must be string[].",
+  "- Do not return objects inside string arrays; put the readable item text directly in the array.",
+  "Example:",
+  JSON.stringify(
+    {
+      title: "示例科技 GEO 内容优化方案",
+      summary: "围绕事实卡重写后的官网文章摘要。",
+      body_markdown: "## 服务能力\n示例科技有限公司提供GEO内容优化服务。",
+      image_suggestions: [],
+      changed_sections: ["title", "body"],
+      requires_user_confirmation: ["客户案例需要确认"],
+    },
+    null,
+    2,
+  ),
+].join("\n");
+
+const QA_OUTPUT_CONTRACT = [
+  "Output type contract:",
+  "- Return { checks: QaCheck[] }.",
+  "- rule_id must reuse the exact English rule_id from deterministicChecks.",
+  "- status must be one of pass, warn, fail.",
+  "- evidence, reason, suggested_fix must be strings.",
+  "- target_agent must be title, body, fact_card, or null.",
+  "Example check:",
+  JSON.stringify(
+    {
+      rule_id: "title_quality",
+      status: "warn",
+      evidence: "标题偏营销化",
+      reason: "官网标题需要更克制",
+      suggested_fix: "改成事实型标题",
+      target_agent: "title",
+    },
+    null,
+    2,
+  ),
+].join("\n");
+
 function formatPlatformGuidance(selected: PublishPlatform) {
   return [
     "平台模板选项：",
@@ -69,6 +141,8 @@ export function buildFactExtractorPrompt(input: ArticleInput) {
     "company_full_name, company_short_names, brand_names, product_names, target_industry, target_audience, experience_years, core_claims, forbidden_claims, image_topics, uncertain_items.",
     "Do not include confirmed_by_user.",
     "",
+    FACT_CARD_OUTPUT_CONTRACT,
+    "",
     "字段要求：",
     "- core_claims 只放原文明示、可作为后续优化硬约束的事实。",
     "- forbidden_claims 放行业第一、最强、知名客户、显著提升、保证转化等无法验证或高风险主张。",
@@ -89,6 +163,8 @@ export function buildArticleOptimizerPrompt(
     "Return an OptimizedArticle JSON object with these exact keys:",
     "title, summary, body_markdown, image_suggestions, changed_sections, requires_user_confirmation.",
     "",
+    OPTIMIZED_ARTICLE_OUTPUT_CONTRACT,
+    "",
     formatPlatformGuidance(input.platform),
     "",
     "输出要求：",
@@ -119,6 +195,7 @@ export function buildQualityInspectorPrompt(input: {
     "Return a JSON object with a checks array.",
     "Each check must include rule_id, status, evidence, reason, suggested_fix, and target_agent.",
     "Only use rule_id values already present in deterministicChecks.",
+    QA_OUTPUT_CONTRACT,
     "不得把 deterministic fail 降级。",
     "",
     formatPlatformGuidance(input.platform),
@@ -146,6 +223,7 @@ export function buildTargetedRewritePrompt(input: {
 }) {
   return [
     "Return an OptimizedArticle JSON object.",
+    OPTIMIZED_ARTICLE_OUTPUT_CONTRACT,
     "Rewrite only the fields needed for failedChecks.",
     "",
     "按 rule_id 执行修复动作：",