refactor(agent): dedupe harness and command workflows

src/agents/skills-install-download.ts

@@ -10,6 +10,7 @@ import { fetchWithSsrFGuard } from "../infra/net/fetch-guard.js";
 import { isWithinDir, resolveSafeBaseDir } from "../infra/path-safety.js";
 import { runCommandWithTimeout } from "../process/exec.js";
 import { ensureDir, resolveUserPath } from "../utils.js";
+import { formatInstallFailureMessage } from "./skills-install-output.js";
 import { hasBinary } from "./skills.js";
 import { resolveSkillToolsRootDir } from "./skills/tools-dir.js";
 
@@ -17,45 +18,6 @@ function isNodeReadableStream(value: unknown): value is NodeJS.ReadableStream {
   return Boolean(value && typeof (value as NodeJS.ReadableStream).pipe === "function");
 }
 
-function summarizeInstallOutput(text: string): string | undefined {
-  const raw = text.trim();
-  if (!raw) {
-    return undefined;
-  }
-  const lines = raw
-    .split("\n")
-    .map((line) => line.trim())
-    .filter(Boolean);
-  if (lines.length === 0) {
-    return undefined;
-  }
-
-  const preferred =
-    lines.find((line) => /^error\b/i.test(line)) ??
-    lines.find((line) => /\b(err!|error:|failed)\b/i.test(line)) ??
-    lines.at(-1);
-
-  if (!preferred) {
-    return undefined;
-  }
-  const normalized = preferred.replace(/\s+/g, " ").trim();
-  const maxLen = 200;
-  return normalized.length > maxLen ? `${normalized.slice(0, maxLen - 1)}…` : normalized;
-}
-
-function formatInstallFailureMessage(result: {
-  code: number | null;
-  stdout: string;
-  stderr: string;
-}): string {
-  const code = typeof result.code === "number" ? `exit ${result.code}` : "unknown exit";
-  const summary = summarizeInstallOutput(result.stderr) ?? summarizeInstallOutput(result.stdout);
-  if (!summary) {
-    return `Install failed (${code})`;
-  }
-  return `Install failed (${code}): ${summary}`;
-}
-
 function isWindowsDrivePath(p: string): boolean {
   return /^[a-zA-Z]:[\\/]/.test(p);
 }