Support nested "use step" declarations in non-workflow functions

[TooTallNate]

Added support for nested "use step" declarations in non-workflow functions.

What changed?

This PR enhances the SWC plugin to properly handle "use step" declarations that appear inside regular functions, not just workflow functions. The implementation:

• Tracks parent function names for all functions, not just workflow functions
• Properly hoists nested step functions from any parent function context
• Maintains correct variable references when hoisting
• Preserves the step functions in client mode by just removing the directive
• Adds comprehensive test cases for various nested step function scenarios

How to test?

Test by creating nested step functions inside regular functions:

function regularFunction(a, b) {
  // This now works properly
  async function nestedStep() {
    'use step';
    return a + b;
  }
  return nestedStep();
}

// Also works with arrow functions and return statements
function returnStepFunction(x) {
  return async () => {
    'use step';
    return x * 2;
  };
}

Verify that these functions are properly hoisted and transformed in step mode, and that they work correctly in workflow and client modes.

Why make this change?

Previously, "use step" declarations were only properly handled when they appeared at the module level or inside workflow functions. This limitation prevented developers from creating utility functions that return or contain step functions. This change enables more flexible code organization patterns, allowing step functions to be created and returned from any function context.

[changeset-bot]

🦋 Changeset detected

Latest commit: bef8c1c

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 10 packages

Name	Type
@workflow/swc-plugin	Patch
@workflow/builders	Patch
@workflow/cli	Patch
@workflow/next	Patch
@workflow/nitro	Patch
@workflow/sveltekit	Patch
workflow	Patch
@workflow/world-testing	Patch
@workflow/nuxt	Patch
@workflow/ai	Patch

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Project	Deployment	Preview	Comments	Updated (UTC)
example-nextjs-workflow-turbopack	Ready	Preview	Comment	Nov 26, 2025 1:35am
example-nextjs-workflow-webpack	Ready	Preview	Comment	Nov 26, 2025 1:35am
example-workflow	Ready	Preview	Comment	Nov 26, 2025 1:35am
workbench-express-workflow	Ready	Preview	Comment	Nov 26, 2025 1:35am
workbench-fastify-workflow	Error			Nov 26, 2025 1:35am
workbench-hono-workflow	Ready	Preview	Comment	Nov 26, 2025 1:35am
workbench-nitro-workflow	Ready	Preview	Comment	Nov 26, 2025 1:35am
workbench-nuxt-workflow	Ready	Preview	Comment	Nov 26, 2025 1:35am
workbench-sveltekit-workflow	Ready	Preview	Comment	Nov 26, 2025 1:35am
workbench-vite-workflow	Ready	Preview	Comment	Nov 26, 2025 1:35am
workflow-docs	Ready	Preview	Comment	Nov 26, 2025 1:35am

[TooTallNate]

• Support "provider-defined" tools in DurableAgent #434 : 2 dependent PRs (#445 , #474 )
• Add AI provider step wrapper functions #428
• Apply workflow function transformation in "step" mode #420
• Support nested "use step" declarations in non-workflow functions #418 👈 (View in Graphite)
• main

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