diff --git a/backend/src/ea_chatbot/api/dependencies.py b/backend/src/ea_chatbot/api/dependencies.py
index e3d2b9f..69d93c8 100644
--- a/backend/src/ea_chatbot/api/dependencies.py
+++ b/backend/src/ea_chatbot/api/dependencies.py
@@ -25,9 +25,8 @@ oauth2_scheme = OAuth2PasswordBearer(tokenUrl="api/v1/auth/login", auto_error=Fa
 
 async def get_current_user(request: Request, token: str = Depends(oauth2_scheme)) -> User:
     """Dependency to get the current authenticated user from the JWT token (cookie or header)."""
-    # Try getting token from cookie first
-    if not token:
-        token = request.cookies.get("access_token")
+    # Prioritize cookie, fallback to header
+    token = request.cookies.get("access_token") or token
 
     credentials_exception = HTTPException(
         status_code=status.HTTP_401_UNAUTHORIZED,
diff --git a/backend/src/ea_chatbot/api/routers/auth.py b/backend/src/ea_chatbot/api/routers/auth.py
index d6792e7..65ca3e6 100644
--- a/backend/src/ea_chatbot/api/routers/auth.py
+++ b/backend/src/ea_chatbot/api/routers/auth.py
@@ -1,4 +1,4 @@
-from fastapi import APIRouter, Depends, HTTPException, status, Response
+from fastapi import APIRouter, Depends, HTTPException, status, Response, Request
 from fastapi.responses import RedirectResponse
 from fastapi.security import OAuth2PasswordRequestForm
 from ea_chatbot.api.utils import create_access_token
@@ -6,6 +6,9 @@ from ea_chatbot.api.dependencies import history_manager, oidc_client, get_curren
 from ea_chatbot.history.models import User as UserDB
 from ea_chatbot.api.schemas import Token, UserCreate, UserResponse
 import os
+import logging
+
+logger = logging.getLogger(__name__)
 
 router = APIRouter(prefix="/auth", tags=["auth"])
 
@@ -80,9 +83,9 @@ async def oidc_login():
     url = oidc_client.get_login_url()
     return {"url": url}
 
-@router.get("/oidc/callback")
-async def oidc_callback(code: str):
-    """Handle the OIDC callback, issue a JWT, and redirect to frontend."""
+@router.get("/oidc/callback", response_model=Token)
+async def oidc_callback(request: Request, response: Response, code: str):
+    """Handle the OIDC callback, issue a JWT, and redirect or return JSON."""
     if not oidc_client:
         raise HTTPException(status_code=status.HTTP_510_NOT_EXTENDED, detail="OIDC not configured")
     
@@ -99,12 +102,29 @@ async def oidc_callback(code: str):
         
         access_token = create_access_token(data={"sub": str(user.id)})
         
-        response = RedirectResponse(url=f"{FRONTEND_URL}/auth/callback")
-        set_auth_cookie(response, access_token)
-        return response
+        # Determine if we should redirect (direct provider callback) or return JSON (frontend exchange)
+        is_ajax = request.headers.get("X-Requested-With") == "XMLHttpRequest" or \
+                 "application/json" in request.headers.get("Accept", "")
+
+        if is_ajax:
+            set_auth_cookie(response, access_token)
+            return {"access_token": access_token, "token_type": "bearer"}
+        else:
+            redirect_response = RedirectResponse(url=f"{FRONTEND_URL}/auth/callback")
+            set_auth_cookie(redirect_response, access_token)
+            return redirect_response
+            
+    except HTTPException:
+        raise
     except Exception as e:
-        # Redirect to frontend with error
-        return RedirectResponse(url=f"{FRONTEND_URL}?error=oidc_failed")
+        logger.exception("OIDC authentication failed")
+        # For non-ajax, redirect with error
+        is_ajax = request.headers.get("X-Requested-With") == "XMLHttpRequest" or \
+                 "application/json" in request.headers.get("Accept", "")
+        if is_ajax:
+            raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="OIDC authentication failed")
+        else:
+            return RedirectResponse(url=f"{FRONTEND_URL}?error=oidc_failed")
 
 @router.get("/me", response_model=UserResponse)
 async def get_me(current_user: UserDB = Depends(get_current_user)):
diff --git a/backend/tests/api/test_agent.py b/backend/tests/api/test_agent.py
index 09fc007..aef9e79 100644
--- a/backend/tests/api/test_agent.py
+++ b/backend/tests/api/test_agent.py
@@ -21,7 +21,7 @@ def auth_header(mock_user):
 
 def test_stream_agent_unauthorized():
     """Test that streaming requires authentication."""
-    response = client.post("/chat/stream", json={"message": "hello"})
+    response = client.post("/api/v1/chat/stream", json={"message": "hello"})
     assert response.status_code == 401
 
 @pytest.mark.asyncio
@@ -52,7 +52,7 @@ async def test_stream_agent_success(auth_header, mock_user):
         mock_session.get.return_value = mock_conv
         
         # Using TestClient with a stream context
-        with client.stream("POST", "/chat/stream", 
+        with client.stream("POST", "/api/v1/chat/stream", 
                           json={"message": "hello", "thread_id": "t1"}, 
                           headers=auth_header) as response:
             assert response.status_code == 200
diff --git a/backend/tests/api/test_api_auth.py b/backend/tests/api/test_api_auth.py
index 9b8d94c..799da97 100644
--- a/backend/tests/api/test_api_auth.py
+++ b/backend/tests/api/test_api_auth.py
@@ -26,7 +26,7 @@ def test_register_user_success():
         mock_hm.create_user.return_value = User(id="1", username="new@example.com", display_name="New")
         
         response = client.post(
-            "/auth/register",
+            "/api/v1/auth/register",
             json={"email": "new@example.com", "password": "password123", "display_name": "New"}
         )
         
@@ -39,7 +39,7 @@ def test_login_success():
         mock_hm.authenticate_user.return_value = User(id="1", username="test@example.com")
         
         response = client.post(
-            "/auth/login",
+            "/api/v1/auth/login",
             data={"username": "test@example.com", "password": "password123"}
         )
         
@@ -53,7 +53,7 @@ def test_login_invalid_credentials():
         mock_hm.authenticate_user.return_value = None
         
         response = client.post(
-            "/auth/login",
+            "/api/v1/auth/login",
             data={"username": "test@example.com", "password": "wrongpassword"}
         )
         
@@ -62,7 +62,7 @@ def test_login_invalid_credentials():
 
 def test_protected_route_without_token():
     """Test that protected routes require a token."""
-    response = client.get("/auth/me")
+    response = client.get("/api/v1/auth/me")
     assert response.status_code == 401
 
 def test_oidc_login_redirect():
@@ -70,12 +70,12 @@ def test_oidc_login_redirect():
     with patch("ea_chatbot.api.routers.auth.oidc_client") as mock_oidc:
         mock_oidc.get_login_url.return_value = "https://oidc-provider.com/auth"
         
-        response = client.get("/auth/oidc/login")
+        response = client.get("/api/v1/auth/oidc/login")
         assert response.status_code == 200
         assert response.json()["url"] == "https://oidc-provider.com/auth"
 
-def test_oidc_callback_success():
-    """Test successful OIDC callback and JWT issuance."""
+def test_oidc_callback_success_ajax():
+    """Test successful OIDC callback and JWT issuance via AJAX."""
     with patch("ea_chatbot.api.routers.auth.oidc_client") as mock_oidc, \
          patch("ea_chatbot.api.routers.auth.history_manager") as mock_hm:
         
@@ -83,7 +83,10 @@ def test_oidc_callback_success():
         mock_oidc.get_user_info.return_value = {"email": "sso@example.com", "name": "SSO User"}
         mock_hm.sync_user_from_oidc.return_value = User(id="sso-123", username="sso@example.com", display_name="SSO User")
         
-        response = client.get("/auth/oidc/callback?code=some-code")
+        response = client.get(
+            "/api/v1/auth/oidc/callback?code=some-code",
+            headers={"Accept": "application/json"}
+        )
         
         assert response.status_code == 200
         assert "access_token" in response.json()
@@ -98,7 +101,7 @@ def test_get_me_success():
         mock_hm.get_user_by_id.return_value = User(id="123", username="test@example.com", display_name="Test")
         
         response = client.get(
-            "/auth/me",
+            "/api/v1/auth/me",
             headers={"Authorization": f"Bearer {token}"}
         )
         
diff --git a/backend/tests/api/test_api_history.py b/backend/tests/api/test_api_history.py
index d322e44..e0b3117 100644
--- a/backend/tests/api/test_api_history.py
+++ b/backend/tests/api/test_api_history.py
@@ -35,7 +35,7 @@ def test_get_conversations_success(auth_header, mock_user):
             )
         ]
         
-        response = client.get("/conversations", headers=auth_header)
+        response = client.get("/api/v1/conversations", headers=auth_header)
         
         assert response.status_code == 200
         assert len(response.json()) == 1
@@ -53,7 +53,7 @@ def test_create_conversation_success(auth_header, mock_user):
         )
         
         response = client.post(
-            "/conversations",
+            "/api/v1/conversations",
             json={"name": "New Conv"},
             headers=auth_header
         )
@@ -75,7 +75,7 @@ def test_get_messages_success(auth_header):
             )
         ]
         
-        response = client.get("/conversations/c1/messages", headers=auth_header)
+        response = client.get("/api/v1/conversations/c1/messages", headers=auth_header)
         
         assert response.status_code == 200
         assert len(response.json()) == 1
@@ -86,7 +86,7 @@ def test_delete_conversation_success(auth_header):
     with patch("ea_chatbot.api.routers.history.history_manager") as mock_hm:
         mock_hm.delete_conversation.return_value = True
         
-        response = client.delete("/conversations/c1", headers=auth_header)
+        response = client.delete("/api/v1/conversations/c1", headers=auth_header)
         assert response.status_code == 204
 
 def test_get_plot_success(auth_header, mock_user):
@@ -109,7 +109,7 @@ def test_get_plot_success(auth_header, mock_user):
             
         mock_session.get.side_effect = mock_get
         
-        response = client.get("/artifacts/plots/p1", headers=auth_header)
+        response = client.get("/api/v1/artifacts/plots/p1", headers=auth_header)
         
         assert response.status_code == 200
         assert response.content == b"fake-image-data"
diff --git a/backend/tests/api/test_persistence.py b/backend/tests/api/test_persistence.py
index d1fb265..0b9089e 100644
--- a/backend/tests/api/test_persistence.py
+++ b/backend/tests/api/test_persistence.py
@@ -46,7 +46,7 @@ def test_persistence_integration_success(auth_header, mock_user):
         mock_session.get.return_value = mock_conv
         
         # Act
-        with client.stream("POST", "/chat/stream", 
+        with client.stream("POST", "/api/v1/chat/stream", 
                           json={"message": "persistence test", "thread_id": "t1"}, 
                           headers=auth_header) as response:
             assert response.status_code == 200