---
title: "Step and Flow close semantics"
description: "Detailed rules for completion requests, Flow outputs, and Step cancellation: what stays in force, what survives a failure, and what a canceled handler still does. The Step and Flow pages explain the concepts."
canonical_url: "https://docs.superdurable.io/reference/server/step-and-flow-close/"
source: "docs/reference/server/step-and-flow-close.mdx"
locale: "en"
---

> Index of every page for AI agents: https://docs.superdurable.io/llms.txt

# Step and Flow close semantics

Detailed rules for completion requests, Flow outputs, and Step cancellation. The
concept pages explain the model: [Flow](https://docs.superdurable.io/concepts/flow.md) and
[Step](https://docs.superdurable.io/concepts/step.md). For the messages a canceled Step consumed, see
[Canceled Steps return consumed messages](https://docs.superdurable.io/reference/server/runtime-data.md#canceled-step-messages).

<a id="completion-requests"></a>

## Completion requests

**GracefulComplete** ends its own branch and asks Dex to complete the Flow. As
soon as no Step is active, Dex begins to complete the Flow. The request stays in
force: a later branch that ends with **DeadEnd** does not withdraw it.

Until no Step is active, other Steps and RPCs can still start new Steps, and
those Steps delay completion too. Once Dex begins to complete the Flow, it
starts no new Step. A naturally closing Flow stays **RUNNING** until its pending Attribute Store
writes finish or are discarded, until transactional or locking RPCs admitted
earlier finish, and until Dex records the close. **WaitForFlow** keeps waiting
meanwhile. See
[Requests during Flow close](https://docs.superdurable.io/reference/server/runtime-client.md#requests-during-flow-close).

Without a pending **GracefulComplete**, a Flow with no active Step keeps
running. An RPC can still start new Steps in it. Dex never closes a Flow because
no Step is active. Something else closes it: its Flow timeout, a stop, or a
completing decision.

<a id="flow-outputs"></a>

## Flow outputs

**GracefulComplete** and **ForceComplete** can carry an output. The Flow result
lists each output with its Step type and Step execution ID.

Only a **COMPLETED** Flow keeps these outputs. A Flow that fails, is canceled, is
terminated, or times out has no outputs, even after an earlier
**GracefulComplete** carried one. Keep data that must survive a failure in an
Attribute.

<a id="step-cancellation"></a>

## Step cancellation

A **StepDecision** or an RPC can cancel active Steps. Dex selects the Steps to
cancel after the decision commits. A decision or an RPC never cancels the Steps
that it starts itself.

Canceling a Step discards everything its current method has not committed: its
Attribute writes, its Channel publications, and its decision. What its earlier
methods committed, such as its **WaitFor** writes, stays.

Cancellation is cooperative. The SDK signals it to the handler. Dex discards the
canceled Step's later result, writes, retries, and recovery routes. A handler
that ignores the signal keeps running, and its calls to external systems still
take effect, even after the Flow has closed.

A Step that a decision or an RPC cancels never takes the Channel messages
published in that same commit. See
[Pending messages](https://docs.superdurable.io/reference/server/runtime-data.md#manage-pending-messages).