First cut

server/src/io/write-content.ts

@@ -0,0 +1,68 @@
+import fs from 'node:fs';
+import path from 'node:path';
+import crypto from 'node:crypto';
+import { stringifyCanonical } from '@dynamic-sites/shared';
+import { writeAuditLog } from '../db.js';
+import { logger } from '../logger.js';
+
+const REPO_ROOT = process.env.REPO_ROOT || '.';
+const MAX_BACKUPS = 20;
+
+function ensureDir(dir: string) {
+  if (!fs.existsSync(dir)) fs.mkdirSync(dir, { recursive: true });
+}
+
+function fileHash(content: string): string {
+  return crypto.createHash('sha256').update(content).digest('hex').slice(0, 12);
+}
+
+/**
+ * Atomic write of canonical JSON to a repo-relative path.
+ * Creates a pre-write backup and audit log entry.
+ */
+export function writeContentFile(
+  repoRelativePath: string,
+  data: unknown,
+  opts?: { proposalId?: string; source?: string }
+): void {
+  const absPath = path.join(REPO_ROOT, repoRelativePath);
+  const canonical = stringifyCanonical(data);
+
+  // Pre-write backup
+  let beforeHash: string | undefined;
+  if (fs.existsSync(absPath)) {
+    const existing = fs.readFileSync(absPath, 'utf-8');
+    beforeHash = fileHash(existing);
+
+    const backupDir = path.join(REPO_ROOT, 'content', '.backups', repoRelativePath);
+    ensureDir(backupDir);
+    const ts = new Date().toISOString().replace(/[:.]/g, '-');
+    fs.copyFileSync(absPath, path.join(backupDir, `${ts}.json`));
+
+    // Prune old backups
+    const backups = fs.readdirSync(backupDir).sort();
+    while (backups.length > MAX_BACKUPS) {
+      const oldest = backups.shift()!;
+      fs.unlinkSync(path.join(backupDir, oldest));
+    }
+  }
+
+  // Atomic write: temp file + rename
+  ensureDir(path.dirname(absPath));
+  const tmpPath = absPath + '.tmp.' + process.pid;
+  fs.writeFileSync(tmpPath, canonical, 'utf-8');
+  fs.renameSync(tmpPath, absPath);
+
+  const afterHash = fileHash(canonical);
+
+  // Audit log
+  writeAuditLog({
+    proposalId: opts?.proposalId,
+    repoRelativePath,
+    beforeHash,
+    afterHash,
+    source: opts?.source || 'http',
+  });
+
+  logger.info({ event: 'content.written', path: repoRelativePath, size: canonical.length }, 'Content file written');
+}