import { mkdirSync, writeFileSync, renameSync } from "node:fs";
import { join } from "node:path";
import { randomUUID } from "node:crypto";

/**
 * Write a read-only `.effective-prompt.md` snapshot for debugging.
 * Best-effort: logs warning on failure, never throws.
 */
export function writeEffectivePrompt(
  agentDir: string,
  composed: { text: string; hash: string },
  meta: { mode: string; version: string },
): void {
  try {
    mkdirSync(agentDir, { recursive: true });
    const dest = join(agentDir, ".effective-prompt.md");
    const header =
      `<!-- Generated by ai-cofounder — do not edit -->\n` +
      `<!-- Mode: ${meta.mode} | Version: ${meta.version} | Hash: ${composed.hash} -->\n\n`;
    const tmp = dest + "." + randomUUID() + ".tmp";
    writeFileSync(tmp, header + composed.text);
    renameSync(tmp, dest);
  } catch (err) {
    console.warn(
      `[effective-prompt] Failed to write snapshot for ${agentDir}:`,
      err,
    );
  }
}