feat: use llm for targeted rewrite

src/lib/workflow/__tests__/llm-integration.test.ts

@@ -16,6 +16,7 @@ vi.mock("../../llm/client", async () => {
 
 import { extractCandidateFactCard } from "../fact-extractor";
 import { optimizeArticle } from "../article-optimizer";
+import { rewriteFailedSections } from "../targeted-rewriter";
 
 describe("LLM workflow integration", () => {
   const confirmedFactCard = {
@@ -127,4 +128,70 @@ describe("LLM workflow integration", () => {
       "Unsupported requested claim: 99 patents",
     );
   });
+
+  it("uses LLM output for targeted rewrite when valid", async () => {
+    llmMocks.generateValidatedJson.mockResolvedValueOnce({
+      title: "Rewritten By LLM",
+      summary: "Original summary",
+      body_markdown:
+        "## Body\nExample Technology Co., Ltd. focuses on GEO optimization.",
+      image_suggestions: [],
+      changed_sections: ["title"],
+      requires_user_confirmation: [],
+    });
+
+    const rewritten = await rewriteFailedSections({
+      article: {
+        title: "Bad title!!!",
+        summary: "Original summary",
+        body_markdown: "## Body\nOriginal body",
+        image_suggestions: [],
+        changed_sections: [],
+        requires_user_confirmation: [],
+      },
+      factCard: confirmedFactCard,
+      failedChecks: [
+        {
+          rule_id: "title_quality",
+          status: "fail",
+          evidence: "Bad title!!!",
+          reason: "Title has punctuation stuffing.",
+          suggested_fix: "Rewrite title.",
+          target_agent: "title",
+        },
+      ],
+    });
+
+    expect(rewritten.title).toBe("Rewritten By LLM");
+    expect(llmMocks.generateValidatedJson).toHaveBeenCalledOnce();
+  });
+
+  it("falls back to deterministic targeted rewrite when LLM returns null", async () => {
+    llmMocks.generateValidatedJson.mockResolvedValueOnce(null);
+
+    const rewritten = await rewriteFailedSections({
+      article: {
+        title: "Bad title!!!",
+        summary: "Original summary",
+        body_markdown: "## Body\nOriginal body",
+        image_suggestions: [],
+        changed_sections: [],
+        requires_user_confirmation: [],
+      },
+      factCard: confirmedFactCard,
+      failedChecks: [
+        {
+          rule_id: "title_quality",
+          status: "fail",
+          evidence: "Bad title!!!",
+          reason: "Title has punctuation stuffing.",
+          suggested_fix: "Rewrite title.",
+          target_agent: "title",
+        },
+      ],
+    });
+
+    expect(rewritten.title).toContain("GEO optimization Guide");
+    expect(rewritten.summary).toBe("Original summary");
+  });
 });

src/lib/workflow/__tests__/workflow.test.ts

@@ -183,7 +183,7 @@ describe("workflow nodes", () => {
     expect(report.overall_status).toBe("fail");
   });
 
-  it("rewrites only the failing target area", () => {
+  it("rewrites only the failing target area", async () => {
     const article = {
       title: "Bad title!!!",
       summary: "Original summary",
@@ -193,7 +193,7 @@ describe("workflow nodes", () => {
       requires_user_confirmation: [],
     };
 
-    const rewritten = rewriteFailedSections({
+    const rewritten = await rewriteFailedSections({
       article,
       factCard: confirmedFactCard,
       failedChecks: [

src/lib/workflow/orchestrator.ts

@@ -24,7 +24,7 @@ export async function runOptimizationWorkflow({
 
   while (qaReport.overall_status === "fail" && rewriteRounds < 2) {
     const failedChecks = qaReport.checks.filter((check) => check.status === "fail");
-    article = rewriteFailedSections({ article, factCard, failedChecks });
+    article = await rewriteFailedSections({ article, factCard, failedChecks });
     rewriteRounds += 1;
     qaReport = inspectQuality({
       article,

src/lib/workflow/targeted-rewriter.ts

@@ -1,4 +1,10 @@
 import type { ConfirmedFactCard, OptimizedArticle, QaCheck } from "../domain/types";
+import { optimizedArticleSchema } from "../domain/validation";
+import { generateValidatedJson } from "../llm/client";
+import {
+  TARGETED_REWRITER_SYSTEM_PROMPT,
+  buildTargetedRewritePrompt,
+} from "../llm/prompts";
 
 export interface RewriteFailedSectionsInput {
   article: OptimizedArticle;
@@ -6,7 +12,22 @@ export interface RewriteFailedSectionsInput {
   failedChecks: QaCheck[];
 }
 
-export function rewriteFailedSections({
+export async function rewriteFailedSections({
+  article,
+  factCard,
+  failedChecks,
+}: RewriteFailedSectionsInput): Promise<OptimizedArticle> {
+  const llmArticle = await generateValidatedJson({
+    schema: optimizedArticleSchema,
+    system: TARGETED_REWRITER_SYSTEM_PROMPT,
+    prompt: buildTargetedRewritePrompt({ article, factCard, failedChecks }),
+    temperature: 0.15,
+  });
+
+  return llmArticle ?? rewriteFailedSectionsFallback({ article, factCard, failedChecks });
+}
+
+function rewriteFailedSectionsFallback({
   article,
   factCard,
   failedChecks,