feat(ingest): content-addressed blob store

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

lib/ingest/blob_store.js

@@ -0,0 +1,34 @@
+import crypto from 'node:crypto';
+import fs from 'node:fs/promises';
+import path from 'node:path';
+
+export class BlobStore {
+  constructor(root) { this.root = root; }
+
+  async hash(buf) {
+    return crypto.createHash('sha256').update(buf).digest('hex');
+  }
+
+  path(sha) {
+    return path.join(this.root, sha.slice(0, 2), sha);
+  }
+
+  async write(buf) {
+    const sha = await this.hash(buf);
+    const dest = this.path(sha);
+    try {
+      await fs.access(dest);
+    } catch {
+      await fs.mkdir(path.dirname(dest), { recursive: true });
+      await fs.writeFile(dest, buf);
+    }
+    return { sha, path: dest };
+  }
+}
+
+let _default = null;
+export function defaultStore() {
+  const root = process.env.BLOB_ROOT || '/var/lib/void/blobs';
+  if (!_default || _default.root !== root) _default = new BlobStore(root);
+  return _default;
+}