Add support for serializing this when invoking step functions

[TooTallNate]

Added support for serializing this context when invoking step functions.

What changed?

• Modified the step function implementation to capture and serialize the this context when it's defined and not the global object
• Updated the step invocation queue item interface to include an optional thisVal property
• Enhanced the step handler to apply the hydrated thisVal when executing step functions

Why make this change?

This enhancement allows step functions to be invoked with an explicit context object using standard JavaScript methods like .call() and .apply(). This is particularly useful for step functions that need to access properties from a specific context, enabling more flexible and idiomatic JavaScript patterns within workflows.

[changeset-bot]

🦋 Changeset detected

Latest commit: 572c60b

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

This PR includes changesets to release 15 packages

Name	Type
@workflow/nitro	Patch
@workflow/swc-plugin	Patch
workflow	Patch
@workflow/core	Patch
@workflow/nuxt	Patch
@workflow/astro	Patch
@workflow/builders	Patch
@workflow/cli	Patch
@workflow/next	Patch
@workflow/rollup	Patch
@workflow/sveltekit	Patch
@workflow/ai	Patch
@workflow/docs-typecheck	Patch
@workflow/world-testing	Patch
@workflow/web-shared	Patch

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[vercel]

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Project	Deployment	Review	Updated (UTC)
example-nextjs-workflow-turbopack	Ready	Preview, Comment	Jan 13, 2026 7:35am
example-nextjs-workflow-webpack	Ready	Preview, Comment	Jan 13, 2026 7:35am
example-workflow	Ready	Preview, Comment	Jan 13, 2026 7:35am
workbench-astro-workflow	Ready	Preview, Comment	Jan 13, 2026 7:35am
workbench-express-workflow	Ready	Preview, Comment	Jan 13, 2026 7:35am
workbench-fastify-workflow	Ready	Preview, Comment	Jan 13, 2026 7:35am
workbench-hono-workflow	Ready	Preview, Comment	Jan 13, 2026 7:35am
workbench-nitro-workflow	Ready	Preview, Comment	Jan 13, 2026 7:35am
workbench-nuxt-workflow	Ready	Preview, Comment	Jan 13, 2026 7:35am
workbench-sveltekit-workflow	Ready	Preview, Comment	Jan 13, 2026 7:35am
workbench-vite-workflow	Ready	Preview, Comment	Jan 13, 2026 7:35am
workflow-docs	Ready	Preview, Comment	Jan 13, 2026 7:35am

[github-actions]

🧪 E2E Test Results

❌ Some tests failed

Summary

	Passed	Failed	Skipped	Total
✅ ▲ Vercel Production	418	0	11	429
✅ 💻 Local Development	382	0	8	390
✅ 📦 Local Production	382	0	8	390
✅ 🐘 Local Postgres	382	0	8	390
✅ 🪟 Windows	39	0	0	39
❌ 🌍 Community Worlds	147	21	0	168
Total	1750	21	35	1806

❌ Failed Tests

🌍 Community Worlds (21 failed)

mongodb (1 failed):

• webhookWorkflow

redis (1 failed):

• webhookWorkflow

starter (18 failed):

• addTenWorkflow
• addTenWorkflow
• error handling error propagation workflow errors nested function calls preserve message and stack trace
• error handling error propagation workflow errors cross-file imports preserve message and stack trace
• error handling error propagation step errors basic step error preserves message and stack trace
• error handling error propagation step errors cross-file step error preserves message and function names in stack
• error handling retry behavior regular Error retries until success
• error handling retry behavior FatalError fails immediately without retries
• error handling catchability FatalError can be caught and detected with FatalError.is()
• hookCleanupTestWorkflow - hook token reuse after workflow completion
• stepFunctionPassingWorkflow - step function references can be passed as arguments (without closure vars)
• stepFunctionWithClosureWorkflow - step function with closure variables passed as argument
• spawnWorkflowFromStepWorkflow - spawning a child workflow using start() inside a step
• pathsAliasWorkflow - TypeScript path aliases resolve correctly
• Calculator.calculate - static workflow method using static step methods from another class
• AllInOneService.processNumber - static workflow method using sibling static step methods
• ChainableService.processWithThis - static step methods using this to reference the class
• thisSerializationWorkflow - step function invoked with .call() and .apply()

turso (1 failed):

• webhookWorkflow

Details by Category

✅ ▲ Vercel Production

App	Passed	Failed	Skipped
✅ astro	38	0	1
✅ example	38	0	1
✅ express	38	0	1
✅ fastify	38	0	1
✅ hono	38	0	1
✅ nextjs-turbopack	38	0	1
✅ nextjs-webpack	38	0	1
✅ nitro	38	0	1
✅ nuxt	38	0	1
✅ sveltekit	38	0	1
✅ vite	38	0	1

✅ 💻 Local Development

App	Passed	Failed	Skipped
✅ astro-stable	38	0	1
✅ express-stable	38	0	1
✅ fastify-stable	38	0	1
✅ hono-stable	38	0	1
✅ nextjs-turbopack-stable	39	0	0
✅ nextjs-webpack-stable	39	0	0
✅ nitro-stable	38	0	1
✅ nuxt-stable	38	0	1
✅ sveltekit-stable	38	0	1
✅ vite-stable	38	0	1

✅ 📦 Local Production

App	Passed	Failed	Skipped
✅ astro-stable	38	0	1
✅ express-stable	38	0	1
✅ fastify-stable	38	0	1
✅ hono-stable	38	0	1
✅ nextjs-turbopack-stable	39	0	0
✅ nextjs-webpack-stable	39	0	0
✅ nitro-stable	38	0	1
✅ nuxt-stable	38	0	1
✅ sveltekit-stable	38	0	1
✅ vite-stable	38	0	1

✅ 🐘 Local Postgres

App	Passed	Failed	Skipped
✅ astro-stable	38	0	1
✅ express-stable	38	0	1
✅ fastify-stable	38	0	1
✅ hono-stable	38	0	1
✅ nextjs-turbopack-stable	39	0	0
✅ nextjs-webpack-stable	39	0	0
✅ nitro-stable	38	0	1
✅ nuxt-stable	38	0	1
✅ sveltekit-stable	38	0	1
✅ vite-stable	38	0	1

✅ 🪟 Windows

App	Passed	Failed	Skipped
✅ nextjs-turbopack	39	0	0

❌ 🌍 Community Worlds

App	Passed	Failed	Skipped
✅ mongodb-dev	3	0	0
❌ mongodb	38	1	0
✅ redis-dev	3	0	0
❌ redis	38	1	0
✅ starter-dev	3	0	0
❌ starter	21	18	0
✅ turso-dev	3	0	0
❌ turso	38	1	0

---

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[TooTallNate]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• Add support for "use step" functions in class instance methods #777
• Add support for custom class instance serialization #762
• Add support for serializing this when invoking step functions #754 👈 (View in Graphite)
• Support class static methods with "use step" / "use workflow" #753
• main

This stack of pull requests is managed by Graphite. Learn more about stacking.

[Copilot]

Pull request overview

This PR adds support for serializing the this context when invoking step functions, enabling the use of JavaScript's .call() and .apply() methods with step functions.

• Modified step function creation to use a regular function instead of an arrow function to capture this context
• Added optional thisVal property to the step invocation queue item interface
• Enhanced serialization/deserialization flow to handle thisVal alongside existing args and closureVars

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
packages/core/src/step.ts	Changed to regular function to capture this and conditionally serialize it when not undefined/null/globalThis
packages/core/src/global.ts	Added optional thisVal property to StepInvocationQueueItem interface
packages/core/src/runtime/suspension-handler.ts	Included thisVal in the dehydrated step input
packages/core/src/runtime/step-handler.ts	Hydrated and applied thisVal when executing step functions, updated comment
workbench/example/workflows/99_e2e.ts	Added example workflow demonstrating .call() and .apply() usage with step functions
packages/core/e2e/e2e.test.ts	Added e2e test validating thisSerializationWorkflow behavior
.changeset/old-pugs-win.md	Added changeset documenting the patch-level change

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