diff --git a/docs/production_deploy.md b/docs/production_deploy.md
index 1d4172d..0a6a14d 100644
--- a/docs/production_deploy.md
+++ b/docs/production_deploy.md
@@ -37,6 +37,10 @@ Install the Python dependency if required:
 python -m pip install boto3
 ```
 
+The PowerShell entry point calls `tool/upload_launcher_release.py` as a regular
+Python file. Keep this helper beside the deployment script; it performs the S3
+upload and verifies the uploaded object's byte length.
+
 Back up `.moonwell_signing\dsa_priv.pem` in the project secret store. Never
 commit it, upload it to Object Storage, or send it through chat. Losing this key
 prevents released launchers from accepting future updates.
diff --git a/tool/deploy_launcher.ps1 b/tool/deploy_launcher.ps1
index 5d0a450..cbee24d 100644
--- a/tool/deploy_launcher.ps1
+++ b/tool/deploy_launcher.ps1
@@ -617,45 +617,15 @@ try {
     $env:MOONWELL_RELEASE_KEY = $S3Key
     $env:MOONWELL_RELEASE_VERSION = $version
     $env:MOONWELL_RELEASE_SHA256 = $installerSha256
-    $uploadScript = @'
-import os
-import boto3
-from botocore.config import Config
+    $uploadHelper = Join-Path `
+        $repositoryRoot `
+        'tool\upload_launcher_release.py'
+    if (-not (Test-Path -LiteralPath $uploadHelper -PathType Leaf)) {
+        throw "S3 upload helper was not found: $uploadHelper"
+    }
 
-path_style = os.getenv("AWS_USE_PATH_STYLE_ENDPOINT", "true").lower()
-addressing_style = "path" if path_style in ("1", "true", "yes") else "virtual"
-s3 = boto3.client(
-    "s3",
-    endpoint_url=os.environ["MOONWELL_RELEASE_ENDPOINT"],
-    region_name=os.getenv("AWS_DEFAULT_REGION", "ru-central1"),
-    config=Config(s3={"addressing_style": addressing_style}),
-)
-s3.upload_file(
-    os.environ["MOONWELL_RELEASE_FILE"],
-    os.environ["MOONWELL_RELEASE_BUCKET"],
-    os.environ["MOONWELL_RELEASE_KEY"],
-    ExtraArgs={
-        "ACL": "public-read",
-        "ContentType": "application/x-msdownload",
-        "CacheControl": "no-cache, max-age=0",
-        "Metadata": {
-            "launcher-version": os.environ["MOONWELL_RELEASE_VERSION"],
-            "sha256": os.environ["MOONWELL_RELEASE_SHA256"],
-        },
-    },
-)
-response = s3.head_object(
-    Bucket=os.environ["MOONWELL_RELEASE_BUCKET"],
-    Key=os.environ["MOONWELL_RELEASE_KEY"],
-)
-print("S3_VERSION_ID=" + str(response.get("VersionId", "")))
-print("S3_CONTENT_LENGTH=" + str(response["ContentLength"]))
-'@
     try {
-        Invoke-RequiredCommand -Command $python -Arguments @(
-            '-c',
-            $uploadScript
-        )
+        Invoke-RequiredCommand -Command $python -Arguments @($uploadHelper)
     }
     finally {
         Remove-Item Env:MOONWELL_RELEASE_FILE -ErrorAction SilentlyContinue
diff --git a/tool/upload_launcher_release.py b/tool/upload_launcher_release.py
new file mode 100644
index 0000000..463c14c
--- /dev/null
+++ b/tool/upload_launcher_release.py
@@ -0,0 +1,70 @@
+"""Upload a MoonWell Launcher installer to S3-compatible storage.
+
+Release metadata is supplied by ``deploy_launcher.ps1`` through environment
+variables. A real Python file avoids Windows PowerShell quoting problems that
+occur when a multiline program is passed to ``python -c``.
+"""
+
+from __future__ import annotations
+
+import os
+from pathlib import Path
+
+import boto3
+from botocore.config import Config
+
+
+def required_environment_value(name: str) -> str:
+    value = os.environ.get(name, "").strip()
+    if not value:
+        raise RuntimeError(f"Required environment variable is missing: {name}")
+    return value
+
+
+release_file = Path(required_environment_value("MOONWELL_RELEASE_FILE"))
+endpoint = required_environment_value("MOONWELL_RELEASE_ENDPOINT")
+bucket = required_environment_value("MOONWELL_RELEASE_BUCKET")
+object_key = required_environment_value("MOONWELL_RELEASE_KEY")
+version = required_environment_value("MOONWELL_RELEASE_VERSION")
+sha256 = required_environment_value("MOONWELL_RELEASE_SHA256")
+
+if not release_file.is_file():
+    raise FileNotFoundError(f"Installer does not exist: {release_file}")
+
+path_style = os.getenv("AWS_USE_PATH_STYLE_ENDPOINT", "true").lower()
+addressing_style = (
+    "path" if path_style in ("1", "true", "yes") else "virtual"
+)
+s3 = boto3.client(
+    "s3",
+    endpoint_url=endpoint,
+    region_name=os.getenv("AWS_DEFAULT_REGION", "ru-central1"),
+    config=Config(s3={"addressing_style": addressing_style}),
+)
+
+s3.upload_file(
+    str(release_file),
+    bucket,
+    object_key,
+    ExtraArgs={
+        "ACL": "public-read",
+        "ContentType": "application/x-msdownload",
+        "CacheControl": "no-cache, max-age=0",
+        "Metadata": {
+            "launcher-version": version,
+            "sha256": sha256,
+        },
+    },
+)
+
+response = s3.head_object(Bucket=bucket, Key=object_key)
+local_size = release_file.stat().st_size
+remote_size = int(response["ContentLength"])
+if remote_size != local_size:
+    raise RuntimeError(
+        f"Uploaded object size mismatch: local={local_size}, "
+        f"remote={remote_size}"
+    )
+
+print("S3_VERSION_ID=" + str(response.get("VersionId", "")))
+print("S3_CONTENT_LENGTH=" + str(remote_size))