---
title: "FlowConfig"
description: "FlowConfig holds runtime behavior. Unlike StartFlowOptions, it is"
canonical_url: "https://docs.superdurable.io/zh-Hans/reference/python/1.37.x/flows-and-steps/flow-config/"
source: "docs/reference-python_versioned_docs/version-1.37.x/flows-and-steps/flow-config.mdx"
locale: "zh-Hans"
---

# FlowConfig

**FlowConfig** holds runtime behavior. Unlike **StartFlowOptions**, it is
mutable after start.

Use **ConfigOverride** in **StartFlowOptions** to change the initial
configuration for one Flow. It changes only the fields you provide. It does not
replace the whole **FlowConfig**. At start, Dex applies the supplied fields
over the Dex Server defaults. Omitted fields keep their default values.

| Field                    | Behavior                                                                                                                                                                                                                                             |
| ------------------------ | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **ActiveStepSearchMode** | Index every active Step, only Steps that ran **WaitFor**, or no active Steps. The built-in server default does not index active Steps. Set an explicit mode to opt in.                                                                               |
| **StepDurability**       | Default durability for methods without a Step override. Dex resolves a method override first, then this value, then **SYNC**. Dex pins the durability when a method call becomes pending, so a change affects only method calls scheduled afterward. |
| **AttributeStoreNames**  | Dex Server Attribute Stores for Attributes that opt in to Attribute sync.                                                                                                                                                                            |

<a id="update-flow-config-with-a-client"></a>

## Update FlowConfig with a Client

Call **UpdateFlowConfig** while the Flow is active. Send only the fields you
want to change. Dex merges them with the existing configuration. The SDK
**UpdateFlowConfig** call does not change the Flow's Worker routing.