diff --git a/upload_to_s3.py b/upload_to_s3.py
index c2ef960..d66d540 100644
--- a/upload_to_s3.py
+++ b/upload_to_s3.py
@@ -1,17 +1,43 @@
 #!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 
+import hashlib
+import json
 import os
 import sys
 from pathlib import Path
 
 import boto3
 from botocore.config import Config
+from botocore.exceptions import ClientError
 
 S3_PREFIX = "World of Warcraft"
 MANIFEST_S3_KEY = "manifest.json"
 
 
+def compute_build_hash(files: list[dict]) -> str:
+    lines = [
+        f'{item["path"]}:{item["size"]}:{item["sha256"]}'
+        for item in sorted(files, key=lambda item: item["path"])
+    ]
+    return hashlib.sha256("\n".join(lines).encode("utf-8")).hexdigest()
+
+
+def merge_manifests(base_manifest: dict, staging_manifest: dict) -> dict:
+    files_by_path = {
+        item["path"]: item
+        for item in base_manifest.get("files", [])
+    }
+    for item in staging_manifest.get("files", []):
+        files_by_path[item["path"]] = item
+
+    files = [files_by_path[path] for path in sorted(files_by_path)]
+    return {
+        "buildHash": compute_build_hash(files),
+        "files": files,
+    }
+
+
 def load_dotenv(env_path: Path) -> dict[str, str]:
     values: dict[str, str] = {}
     if not env_path.exists():
@@ -61,6 +87,38 @@ def main() -> int:
         config=Config(s3={"addressing_style": "path"}) if use_path_style else None,
     )
 
+    manifest_path = project_root / "manifest.json"
+    if not manifest_path.exists():
+        print("ERROR: manifest.json not found", file=sys.stderr)
+        return 1
+
+    try:
+        staging_manifest = json.loads(manifest_path.read_text(encoding="utf-8"))
+    except (OSError, json.JSONDecodeError) as error:
+        print(f"ERROR: unable to read local manifest.json: {error}", file=sys.stderr)
+        return 1
+
+    try:
+        response = s3.get_object(Bucket=bucket, Key=MANIFEST_S3_KEY)
+        production_manifest = json.loads(response["Body"].read())
+    except ClientError as error:
+        error_code = error.response.get("Error", {}).get("Code")
+        if error_code not in {"NoSuchKey", "404"}:
+            print(f"ERROR: unable to read production manifest: {error}", file=sys.stderr)
+            return 1
+        production_manifest = {"files": []}
+    except (UnicodeDecodeError, json.JSONDecodeError) as error:
+        print(f"ERROR: invalid production manifest: {error}", file=sys.stderr)
+        return 1
+
+    merged_manifest = merge_manifests(production_manifest, staging_manifest)
+    print(
+        "Manifest merge: "
+        f"production={len(production_manifest.get('files', []))}, "
+        f"staging={len(staging_manifest.get('files', []))}, "
+        f"result={len(merged_manifest['files'])}"
+    )
+
     dist_dir = project_root / "dist"
     if not dist_dir.exists():
         print(f"ERROR: dist/ directory not found. Run build first.", file=sys.stderr)
@@ -87,18 +145,26 @@ def main() -> int:
             errors = True
 
     # Загрузка манифеста
-    manifest_path = project_root / "manifest.json"
-    if not manifest_path.exists():
-        print(f"ERROR: manifest.json not found", file=sys.stderr)
+    if errors:
+        print("\nFinished with errors; production manifest was not changed.")
         return 1
 
+    manifest_path.write_text(
+        json.dumps(merged_manifest, ensure_ascii=False, indent=2) + "\n",
+        encoding="utf-8",
+        newline="\n",
+    )
+
     print(f"Uploading manifest.json -> s3://{bucket}/{MANIFEST_S3_KEY}")
     try:
         s3.upload_file(
             str(manifest_path),
             bucket,
             MANIFEST_S3_KEY,
-            ExtraArgs={"ContentType": "application/json"},
+            ExtraArgs={
+                "ContentType": "application/json",
+                "CacheControl": "no-cache, no-store, must-revalidate",
+            },
         )
         print(f"  OK")
     except Exception as e: