diff --git a/apps/api/app/core/dependencies.py b/apps/api/app/core/dependencies.py
index de7b3a636..bf56d39c8 100644
--- a/apps/api/app/core/dependencies.py
+++ b/apps/api/app/core/dependencies.py
@@ -7,6 +7,7 @@
 from fastapi import Depends, Header, Request
 from jwt import PyJWKClient
 from loguru import logger
+from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from shared.core.config import settings
@@ -14,6 +15,7 @@
 from shared.core.exceptions.domain_exceptions import (
     AuthException,
 )
+from shared.models.database.user import User
 from shared.utils.api_keys import is_api_key_token
 
 # Standard JWKS endpoint path (fixed, following OpenID Connect convention)
@@ -106,6 +108,23 @@ def decode_jwt_token(token: str) -> str:
         raise AuthException(user_message="Invalid token")
 
 
+async def _ensure_authenticated_user_exists(
+    db: AsyncSession,
+    user_id: str,
+) -> None:
+    result = await db.execute(select(User.id).where(User.id == user_id).limit(1))
+    if result.scalar_one_or_none() is not None:
+        return
+
+    raise AuthException(
+        user_message="Invalid authentication credentials",
+        internal_message=(
+            "Authenticated user id is not present in the user table: "
+            f"user_id={user_id}"
+        ),
+    )
+
+
 async def get_current_user_id(
     request: Request,
     authorization: str | None = Header(
@@ -134,4 +153,6 @@ async def get_current_user_id(
         raise AuthException(user_message="Invalid API Key")
 
     # Mode 2: JWT verification (for Dashboard/Internal)
-    return decode_jwt_token(token)
+    user_id = decode_jwt_token(token)
+    await _ensure_authenticated_user_exists(db, user_id)
+    return user_id
diff --git a/apps/api/tests/contract/test_job_creation_contract.py b/apps/api/tests/contract/test_job_creation_contract.py
index 7b4025b44..b6cfa1375 100644
--- a/apps/api/tests/contract/test_job_creation_contract.py
+++ b/apps/api/tests/contract/test_job_creation_contract.py
@@ -1,11 +1,12 @@
 from collections.abc import Callable
 from contextlib import AbstractAsyncContextManager
-from datetime import datetime, timezone
+from datetime import datetime, timedelta, timezone
 import json
 import socket
 from typing import cast
 from uuid import uuid4
 
+import jwt
 import pytest
 from httpx import AsyncClient
 from pytest import MonkeyPatch
@@ -405,6 +406,53 @@ async def test_should_reject_a_malformed_authorization_header_when_creating_a_jo
     assert await _count_jobs() == 0
 
 
+@pytest.mark.asyncio
+async def test_should_reject_authenticated_user_id_missing_from_user_table(
+    api_client_factory: Callable[[], AbstractAsyncContextManager[AsyncClient]],
+    monkeypatch: MonkeyPatch,
+) -> None:
+    user_id = f"contract-missing-user-{uuid4().hex[:12]}"
+    jwt_secret = f"contract-jwt-secret-{uuid4().hex[:12]}"
+    token = jwt.encode(
+        {
+            "id": user_id,
+            "exp": datetime.now(timezone.utc) + timedelta(minutes=5),
+        },
+        jwt_secret,
+        algorithm="HS256",
+    )
+    payload: dict[str, str] = {
+        "namespace": "contract-jobs",
+        "source_type": "file",
+        "file_name": "contract-upload.pdf",
+        "data_id": "contract-job-missing-user",
+    }
+
+    async with api_client_factory() as api_client:
+        from app.core import dependencies as auth_dependencies
+
+        monkeypatch.setattr(
+            auth_dependencies,
+            "_get_verification_key",
+            lambda _token: jwt_secret,
+        )
+
+        api_client.headers.update({"Authorization": f"Bearer {token}"})
+        response = await api_client.post("/api/v1/jobs", json=payload)
+
+    assert response.status_code == 401
+    assert response.headers["x-request-id"]
+
+    response_json: dict[str, object] = response.json()
+    error = cast(dict[str, object], response_json["error"])
+
+    assert response_json["success"] is False
+    assert error["code"] == "UNAUTHENTICATED"
+    assert error["message"] == "Invalid authentication credentials"
+    assert "details" not in error
+    assert await _count_jobs() == 0
+
+
 @pytest.mark.asyncio
 async def test_should_return_conflict_when_creating_a_job_for_a_document_with_an_active_ingestion_job(
     developer_api_client_factory: Callable[
diff --git a/packages/shared-python/shared/services/billing/credits_service.py b/packages/shared-python/shared/services/billing/credits_service.py
index e4c8e03c8..d0dc48fc4 100644
--- a/packages/shared-python/shared/services/billing/credits_service.py
+++ b/packages/shared-python/shared/services/billing/credits_service.py
@@ -16,7 +16,9 @@
 
 from shared.core.billing import MicroDollar
 from shared.core.config import settings
-from shared.core.exceptions.domain_exceptions import InsufficientCreditsException
+from shared.core.exceptions.domain_exceptions import (
+    InsufficientCreditsException,
+)
 from shared.core.logging import logger
 from shared.models.database.credits_transaction import CreditsTransaction
 from shared.models.database.payment_record import PaymentRecord
diff --git a/packages/shared-python/shared/services/billing/credits_sync_service.py b/packages/shared-python/shared/services/billing/credits_sync_service.py
index ba6ddbe38..e6eb63446 100644
--- a/packages/shared-python/shared/services/billing/credits_sync_service.py
+++ b/packages/shared-python/shared/services/billing/credits_sync_service.py
@@ -11,7 +11,9 @@
 
 from shared.core.billing import MicroDollar
 from shared.core.config import settings
-from shared.core.exceptions.domain_exceptions import InsufficientCreditsException
+from shared.core.exceptions.domain_exceptions import (
+    InsufficientCreditsException,
+)
 from shared.core.logging import logger
 from shared.models.database.credits_transaction import CreditsTransaction
 from shared.models.database.payment_record import PaymentRecord