diff --git a/app/logic/id_gen.py b/app/logic/id_gen.py
new file mode 100644
index 0000000..0cb6fc0
--- /dev/null
+++ b/app/logic/id_gen.py
@@ -0,0 +1,23 @@
+import time
+from sqlalchemy.orm import Session
+from app.models.document import Document
+
+
+def generate_document_id(db: Session) -> str:
+    ts = int(time.time())
+    ts_hex = format(ts, "x")
+
+    n = 0
+    while True:
+        n_hex = format(n, "x")
+        candidate = f"doc_{ts_hex}-{n_hex}"
+
+        exists = (
+            db.query(Document)
+            .filter(Document.document_id == candidate)
+            .first()
+        )
+        if not exists:
+            return candidate
+
+        n += 1
diff --git a/app/logic/ingest.py b/app/logic/ingest.py
index bbd42ac..b40227f 100644
--- a/app/logic/ingest.py
+++ b/app/logic/ingest.py
@@ -9,7 +9,6 @@ import subprocess
 import tempfile
 from difflib import SequenceMatcher
 from pathlib import Path
-from uuid import uuid4
 
 from PIL import Image
 from sqlalchemy import func
@@ -19,6 +18,7 @@ from app.core.config import DOCUMENT_ARCHIVE_ROOT, INBOX_ROOT, UPLOAD_ROOT
 from app.models.document import Document
 from app.models.document_version import DocumentVersion
 from app.models.text_version import TextVersion
+from app.logic.id_gen import generate_document_id
 
 
 ALLOWED_EXTENSIONS = {".pdf", ".jpg", ".jpeg", ".png"}
@@ -304,7 +304,7 @@ def archive_document(
     if not is_supported_file(source):
         raise ValueError(f"Unsupported file type: {source.suffix}")
 
-    document_id = f"doc_{uuid4().hex[:12]}"
+    document_id = generate_document_id(db)
     current_path = build_storage_path(document_id, source)
 
     current_path.parent.mkdir(parents=True, exist_ok=True)
@@ -436,7 +436,8 @@ def ingest_uploaded_file(
     upload_root = Path(UPLOAD_ROOT)
     upload_root.mkdir(parents=True, exist_ok=True)
 
-    staged_name = f"{uuid4().hex[:12]}_{Path(filename).name}"
+    document_id = generate_document_id(db)
+    staged_name = f"{document_id}_{Path(filename).name}"
     staged_path = upload_root / staged_name
     staged_path.write_bytes(file_bytes)