fix(formatters): escape step titles in Seer output and remove dead string[] shim in writeOutput

Author: BYK

src/lib/formatters/output.ts

@@ -12,8 +12,8 @@ import { writeJson } from "./json.js";
 type WriteOutputOptions<T> = {
   /** Output JSON format instead of human-readable */
   json: boolean;
-  /** Function to format data as a rendered string or string array */
-  formatHuman: (data: T) => string | string[];
+  /** Function to format data as a rendered string */
+  formatHuman: (data: T) => string;
   /** Optional source description if data was auto-detected */
   detectedFrom?: string;
 };
@@ -36,8 +36,7 @@ export function writeOutput<T>(
     return;
   }
 
-  const output = options.formatHuman(data);
-  const text = Array.isArray(output) ? output.join("\n") : output;
+  const text = options.formatHuman(data);
   stdout.write(`${text}\n`);
 
   if (options.detectedFrom) {

src/lib/formatters/seer.ts

@@ -124,7 +124,7 @@ function buildRootCauseMarkdown(cause: RootCause, index: number): string {
     lines.push("**Reproduction steps:**");
     lines.push("");
     for (const step of cause.root_cause_reproduction) {
-      lines.push(`**${step.title}**`);
+      lines.push(`**${escapeMarkdownInline(step.title)}**`);
       lines.push("");
       // code_snippet_and_analysis may itself contain markdown (code fences,
       // inline code, etc.) — pass it through as-is so marked renders it.
@@ -270,7 +270,7 @@ export function formatSolution(solution: SolutionArtifact): string {
     for (let i = 0; i < solution.data.steps.length; i++) {
       const step = solution.data.steps[i];
       if (step) {
-        lines.push(`${i + 1}. **${step.title}**`);
+        lines.push(`${i + 1}. **${escapeMarkdownInline(step.title)}**`);
         lines.push("");
         // step.description may contain markdown — pass it through as-is
         lines.push(`   ${step.description.split("\n").join("\n   ")}`);