feat: modularize flattener tool into separate components with improved project root detection (#417)

tools/flattener/prompts.js

@@ -0,0 +1,44 @@
+const os = require("node:os");
+const path = require("node:path");
+const readline = require("node:readline");
+const process = require("node:process");
+
+function expandHome(p) {
+  if (!p) return p;
+  if (p.startsWith("~")) return path.join(os.homedir(), p.slice(1));
+  return p;
+}
+
+function createRl() {
+  return readline.createInterface({
+    input: process.stdin,
+    output: process.stdout,
+  });
+}
+
+function promptQuestion(question) {
+  return new Promise((resolve) => {
+    const rl = createRl();
+    rl.question(question, (answer) => {
+      rl.close();
+      resolve(answer);
+    });
+  });
+}
+
+async function promptYesNo(question, defaultYes = true) {
+  const suffix = defaultYes ? " [Y/n] " : " [y/N] ";
+  const ans = (await promptQuestion(`${question}${suffix}`)).trim().toLowerCase();
+  if (!ans) return defaultYes;
+  if (["y", "yes"].includes(ans)) return true;
+  if (["n", "no"].includes(ans)) return false;
+  return promptYesNo(question, defaultYes);
+}
+
+async function promptPath(question, defaultValue) {
+  const prompt = `${question}${defaultValue ? ` (default: ${defaultValue})` : ""}: `;
+  const ans = (await promptQuestion(prompt)).trim();
+  return expandHome(ans || defaultValue);
+}
+
+module.exports = { promptYesNo, promptPath, promptQuestion, expandHome };