diff --git a/nextcloud_mcp_server/api/passwords.py b/nextcloud_mcp_server/api/passwords.py
index 212355b9..19ae1bdf 100644
--- a/nextcloud_mcp_server/api/passwords.py
+++ b/nextcloud_mcp_server/api/passwords.py
@@ -238,6 +238,24 @@ async def provision_app_password(request: Request) -> JSONResponse:
             status_code=400,
         )
 
+    # Parse optional scopes and the Nextcloud loginName from the request body
+    # up front. Nextcloud authenticates app passwords against the *loginName*,
+    # which can differ from the UID — e.g. OIDC-provisioned users whose UID is
+    # their display name (UID "Chris Coutinho", loginName "chris@coutinho.io").
+    # Use the loginName for the BasicAuth validation below, falling back to the
+    # path user_id for legacy callers that don't send one (where UID ==
+    # loginName).
+    scopes = None
+    nc_username = None
+    try:
+        body = await request.json()
+        scopes = body.get("scopes")  # list[str] | None
+        nc_username = body.get("username")  # Nextcloud loginName
+    except Exception:
+        pass  # No JSON body = legacy call without scopes / loginName
+
+    login_name = nc_username or username
+
     # Get Nextcloud host from settings
     settings = get_settings()
     nextcloud_host = settings.nextcloud_host
@@ -249,7 +267,10 @@ async def provision_app_password(request: Request) -> JSONResponse:
             status_code=500,
         )
 
-    # Validate app password against Nextcloud
+    # Validate app password against Nextcloud. BasicAuth places the user-id
+    # literally in the header (RFC 7617 — no URL-encoding) and Nextcloud keys
+    # app-password auth on the loginName, so authenticate as the loginName, not
+    # the UID.
     try:
         async with nextcloud_httpx_client(
             timeout=NEXTCLOUD_VALIDATION_TIMEOUT
@@ -258,7 +279,7 @@ async def provision_app_password(request: Request) -> JSONResponse:
             test_url = f"{nextcloud_host}/ocs/v1.php/cloud/user"
             response = await client.get(
                 test_url,
-                auth=(username, app_password),
+                auth=(login_name, app_password),
                 params={"format": "json"},
                 headers={"OCS-APIRequest": "true"},
             )
@@ -274,10 +295,11 @@ async def provision_app_password(request: Request) -> JSONResponse:
                     status_code=401,
                 )
 
-            # Verify the user ID from response matches
+            # Verify the authenticated account maps to the path user_id (UID):
+            # the loginName must resolve to the UID claimed in the URL path.
             data = response.json()
             ocs_user_id = data.get("ocs", {}).get("data", {}).get("id")
-            if ocs_user_id != username:
+            if ocs_user_id != path_user_id:
                 logger.warning("User ID mismatch in OCS response")
                 _record_rate_limit_attempt(path_user_id, success=False)
                 return JSONResponse(
@@ -292,16 +314,6 @@ async def provision_app_password(request: Request) -> JSONResponse:
             status_code=500,
         )
 
-    # Parse optional scopes and username from request body
-    scopes = None
-    nc_username = None
-    try:
-        body = await request.json()
-        scopes = body.get("scopes")  # list[str] | None
-        nc_username = body.get("username")  # Nextcloud loginName
-    except Exception:
-        pass  # No JSON body = legacy call without scopes
-
     # Store the validated app password
     try:
         storage = await _get_app_password_storage(request)
diff --git a/tests/unit/test_management_app_password_endpoints.py b/tests/unit/test_management_app_password_endpoints.py
index 2f0fd0f3..0a6fcb55 100644
--- a/tests/unit/test_management_app_password_endpoints.py
+++ b/tests/unit/test_management_app_password_endpoints.py
@@ -248,6 +248,64 @@ async def test_provision_app_password_success(temp_storage, mocker):
     stored_password = await temp_storage.get_app_password("testuser")
     assert stored_password == "aaaaa-bbbbb-ccccc-ddddd-eeeee"
 
+    # Legacy callers send no loginName in the body → the OCS validation falls
+    # back to authenticating as the UID (here UID == loginName).
+    _, get_kwargs = mock_client.get.call_args
+    assert get_kwargs["auth"] == ("testuser", "aaaaa-bbbbb-ccccc-ddddd-eeeee")
+
+
+async def test_provision_app_password_uses_loginname_not_uid(temp_storage, mocker):
+    """Regression: when the Nextcloud UID differs from the loginName (e.g.
+    OIDC-provisioned users whose UID is their display name — UID
+    "Chris Coutinho", loginName "chris@coutinho.io"), the OCS BasicAuth
+    validation must authenticate as the loginName from the request body, not
+    the UID. Authenticating as the UID is rejected by Nextcloud with HTTP 401.
+    """
+    mocker.patch(
+        "nextcloud_mcp_server.api.passwords.get_settings",
+        return_value=MagicMock(
+            nextcloud_host="http://localhost:8080",
+            nextcloud_verify_ssl=True,
+            nextcloud_ca_bundle=None,
+        ),
+    )
+
+    # OCS validation succeeds and reports the UID as the account id.
+    mock_response = MagicMock()
+    mock_response.status_code = 200
+    mock_response.json.return_value = {"ocs": {"data": {"id": "Chris Coutinho"}}}
+
+    mock_client = AsyncMock()
+    mock_client.get = AsyncMock(return_value=mock_response)
+    mock_client.__aenter__ = AsyncMock(return_value=mock_client)
+    mock_client.__aexit__ = AsyncMock()
+    mocker.patch(
+        "nextcloud_mcp_server.api.passwords.nextcloud_httpx_client",
+        return_value=mock_client,
+    )
+
+    app = create_test_app(temp_storage)
+    client = TestClient(app)
+
+    pw = "aaaaa-bbbbb-ccccc-ddddd-eeeee"
+    # A literal space in the path is encoded by the client and decoded back to
+    # the UID; the BasicAuth username matches that UID.
+    response = client.post(
+        "/api/v1/users/Chris Coutinho/app-password",
+        headers={"Authorization": create_basic_auth_header("Chris Coutinho", pw)},
+        json={"username": "chris@coutinho.io"},
+    )
+
+    assert response.status_code == 200
+    assert response.json()["success"] is True
+
+    # The OCS BasicAuth used the loginName from the body, not the UID.
+    _, get_kwargs = mock_client.get.call_args
+    assert get_kwargs["auth"] == ("chris@coutinho.io", pw)
+
+    # Stored under the UID (the identity key).
+    assert await temp_storage.get_app_password("Chris Coutinho") == pw
+
 
 async def test_provision_app_password_nextcloud_validation_fails(mocker):
     """Test that failed Nextcloud validation returns 401."""