Ensure class serialization / deserialization only happens in the proper global context

[TooTallNate]

Fixed class serialization/deserialization to properly respect VM context boundaries, ensuring workflow code only accesses classes registered in its own global context.

What changed?

• Modified getSerializationClass() to no longer fall back to checking globalThis when a class isn't found in the provided global context
• Updated the serialization tests to properly simulate how classes are registered and accessed in both host and VM contexts
• Added VM-specific class registration in tests to better match production behavior where workflow code runs in isolation

How to test?

• Run the updated serialization tests which now properly simulate the VM boundary
• Verify that class serialization/deserialization works correctly when classes are registered in their respective contexts
• Confirm that classes registered in one context aren't accessible from another context

Why make this change?

This change ensures proper isolation between the host environment and workflow VM contexts, matching production serverless behavior where workflow code runs in isolation. Previously, the code could leak class registrations between contexts, potentially causing unexpected behavior or security issues. This fix maintains proper boundaries between execution contexts.

[changeset-bot]

🦋 Changeset detected

Latest commit: 55dc421

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

This PR includes changesets to release 17 packages

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

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[github-actions]

🧪 E2E Test Results

❌ Some tests failed

Summary

	Passed	Failed	Skipped	Total
✅ ▲ Vercel Production	457	0	38	495
✅ 💻 Local Development	418	0	32	450
✅ 📦 Local Production	418	0	32	450
✅ 🐘 Local Postgres	418	0	32	450
✅ 🪟 Windows	45	0	0	45
❌ 🌍 Community Worlds	30	162	0	192
✅ 📋 Other	123	0	12	135
Total	1909	162	146	2217

❌ Failed Tests

🌍 Community Worlds (162 failed)

mongodb (40 failed):

• addTenWorkflow
• addTenWorkflow
• should work with react rendering in step
• promiseAllWorkflow
• promiseRaceWorkflow
• promiseAnyWorkflow
• readableStreamWorkflow
• hookWorkflow
• webhookWorkflow
• sleepingWorkflow
• nullByteWorkflow
• workflowAndStepMetadataWorkflow
• outputStreamWorkflow
• outputStreamInsideStepWorkflow - getWritable() called inside step functions
• fetchWorkflow
• promiseRaceStressTestWorkflow
• 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 retry behavior RetryableError respects custom retryAfter delay
• error handling retry behavior maxRetries=0 disables retries
• error handling catchability FatalError can be caught and detected with FatalError.is()
• hookCleanupTestWorkflow - hook token reuse after workflow completion
• concurrent hook token conflict - two workflows cannot use the same hook token simultaneously
• stepFunctionPassingWorkflow - step function references can be passed as arguments (without closure vars)
• stepFunctionWithClosureWorkflow - step function with closure variables passed as argument
• closureVariableWorkflow - nested step functions with closure variables
• 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()
• customSerializationWorkflow - custom class serialization with WORKFLOW_SERIALIZE/WORKFLOW_DESERIALIZE
• pages router addTenWorkflow via pages router
• pages router promiseAllWorkflow via pages router
• pages router sleepingWorkflow via pages router

redis (40 failed):

• addTenWorkflow
• addTenWorkflow
• should work with react rendering in step
• promiseAllWorkflow
• promiseRaceWorkflow
• promiseAnyWorkflow
• readableStreamWorkflow
• hookWorkflow
• webhookWorkflow
• sleepingWorkflow
• nullByteWorkflow
• workflowAndStepMetadataWorkflow
• outputStreamWorkflow
• outputStreamInsideStepWorkflow - getWritable() called inside step functions
• fetchWorkflow
• promiseRaceStressTestWorkflow
• 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 retry behavior RetryableError respects custom retryAfter delay
• error handling retry behavior maxRetries=0 disables retries
• error handling catchability FatalError can be caught and detected with FatalError.is()
• hookCleanupTestWorkflow - hook token reuse after workflow completion
• concurrent hook token conflict - two workflows cannot use the same hook token simultaneously
• stepFunctionPassingWorkflow - step function references can be passed as arguments (without closure vars)
• stepFunctionWithClosureWorkflow - step function with closure variables passed as argument
• closureVariableWorkflow - nested step functions with closure variables
• 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()
• customSerializationWorkflow - custom class serialization with WORKFLOW_SERIALIZE/WORKFLOW_DESERIALIZE
• pages router addTenWorkflow via pages router
• pages router promiseAllWorkflow via pages router
• pages router sleepingWorkflow via pages router

starter (41 failed):

• addTenWorkflow
• addTenWorkflow
• should work with react rendering in step
• promiseAllWorkflow
• promiseRaceWorkflow
• promiseAnyWorkflow
• readableStreamWorkflow
• hookWorkflow
• webhookWorkflow
• sleepingWorkflow
• nullByteWorkflow
• workflowAndStepMetadataWorkflow
• outputStreamWorkflow
• outputStreamInsideStepWorkflow - getWritable() called inside step functions
• fetchWorkflow
• promiseRaceStressTestWorkflow
• 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 retry behavior RetryableError respects custom retryAfter delay
• error handling retry behavior maxRetries=0 disables retries
• error handling catchability FatalError can be caught and detected with FatalError.is()
• hookCleanupTestWorkflow - hook token reuse after workflow completion
• concurrent hook token conflict - two workflows cannot use the same hook token simultaneously
• stepFunctionPassingWorkflow - step function references can be passed as arguments (without closure vars)
• stepFunctionWithClosureWorkflow - step function with closure variables passed as argument
• closureVariableWorkflow - nested step functions with closure variables
• spawnWorkflowFromStepWorkflow - spawning a child workflow using start() inside a step
• health check (CLI) - workflow health command reports healthy endpoints
• 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()
• customSerializationWorkflow - custom class serialization with WORKFLOW_SERIALIZE/WORKFLOW_DESERIALIZE
• pages router addTenWorkflow via pages router
• pages router promiseAllWorkflow via pages router
• pages router sleepingWorkflow via pages router

turso (41 failed):

• addTenWorkflow
• addTenWorkflow
• should work with react rendering in step
• promiseAllWorkflow
• promiseRaceWorkflow
• promiseAnyWorkflow
• readableStreamWorkflow
• hookWorkflow
• webhookWorkflow
• sleepingWorkflow
• nullByteWorkflow
• workflowAndStepMetadataWorkflow
• outputStreamWorkflow
• outputStreamInsideStepWorkflow - getWritable() called inside step functions
• fetchWorkflow
• promiseRaceStressTestWorkflow
• 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 retry behavior RetryableError respects custom retryAfter delay
• error handling retry behavior maxRetries=0 disables retries
• error handling catchability FatalError can be caught and detected with FatalError.is()
• hookCleanupTestWorkflow - hook token reuse after workflow completion
• concurrent hook token conflict - two workflows cannot use the same hook token simultaneously
• stepFunctionPassingWorkflow - step function references can be passed as arguments (without closure vars)
• stepFunctionWithClosureWorkflow - step function with closure variables passed as argument
• closureVariableWorkflow - nested step functions with closure variables
• spawnWorkflowFromStepWorkflow - spawning a child workflow using start() inside a step
• health check (CLI) - workflow health command reports healthy endpoints
• 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()
• customSerializationWorkflow - custom class serialization with WORKFLOW_SERIALIZE/WORKFLOW_DESERIALIZE
• pages router addTenWorkflow via pages router
• pages router promiseAllWorkflow via pages router
• pages router sleepingWorkflow via pages router

Details by Category

✅ ▲ Vercel Production

App	Passed	Failed	Skipped
✅ astro	41	0	4
✅ example	41	0	4
✅ express	41	0	4
✅ fastify	41	0	4
✅ hono	41	0	4
✅ nextjs-turbopack	44	0	1
✅ nextjs-webpack	44	0	1
✅ nitro	41	0	4
✅ nuxt	41	0	4
✅ sveltekit	41	0	4
✅ vite	41	0	4

✅ 💻 Local Development

App	Passed	Failed	Skipped
✅ astro-stable	41	0	4
✅ express-stable	41	0	4
✅ fastify-stable	41	0	4
✅ hono-stable	41	0	4
✅ nextjs-turbopack-stable	45	0	0
✅ nextjs-webpack-stable	45	0	0
✅ nitro-stable	41	0	4
✅ nuxt-stable	41	0	4
✅ sveltekit-stable	41	0	4
✅ vite-stable	41	0	4

✅ 📦 Local Production

App	Passed	Failed	Skipped
✅ astro-stable	41	0	4
✅ express-stable	41	0	4
✅ fastify-stable	41	0	4
✅ hono-stable	41	0	4
✅ nextjs-turbopack-stable	45	0	0
✅ nextjs-webpack-stable	45	0	0
✅ nitro-stable	41	0	4
✅ nuxt-stable	41	0	4
✅ sveltekit-stable	41	0	4
✅ vite-stable	41	0	4

✅ 🐘 Local Postgres

App	Passed	Failed	Skipped
✅ astro-stable	41	0	4
✅ express-stable	41	0	4
✅ fastify-stable	41	0	4
✅ hono-stable	41	0	4
✅ nextjs-turbopack-stable	45	0	0
✅ nextjs-webpack-stable	45	0	0
✅ nitro-stable	41	0	4
✅ nuxt-stable	41	0	4
✅ sveltekit-stable	41	0	4
✅ vite-stable	41	0	4

✅ 🪟 Windows

App	Passed	Failed	Skipped
✅ nextjs-turbopack	45	0	0

❌ 🌍 Community Worlds

App	Passed	Failed	Skipped
✅ mongodb-dev	3	0	0
❌ mongodb	5	40	0
✅ redis-dev	3	0	0
❌ redis	5	40	0
✅ starter-dev	3	0	0
❌ starter	4	41	0
✅ turso-dev	3	0	0
❌ turso	4	41	0

✅ 📋 Other

App	Passed	Failed	Skipped
✅ e2e-local-dev-nest-stable	41	0	4
✅ e2e-local-postgres-nest-stable	41	0	4
✅ e2e-local-prod-nest-stable	41	0	4

---

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Project	Deployment	Actions	Updated (UTC)
example-nextjs-workflow-turbopack	Ready	Preview, Comment, Open in v0	Jan 30, 2026 8:36pm
example-nextjs-workflow-webpack	Ready	Preview, Comment, Open in v0	Jan 30, 2026 8:36pm
example-workflow	Ready	Preview, Comment, Open in v0	Jan 30, 2026 8:36pm
workbench-astro-workflow	Ready	Preview, Comment, Open in v0	Jan 30, 2026 8:36pm
workbench-express-workflow	Ready	Preview, Comment, Open in v0	Jan 30, 2026 8:36pm
workbench-fastify-workflow	Ready	Preview, Comment, Open in v0	Jan 30, 2026 8:36pm
workbench-hono-workflow	Ready	Preview, Comment, Open in v0	Jan 30, 2026 8:36pm
workbench-nitro-workflow	Ready	Preview, Comment, Open in v0	Jan 30, 2026 8:36pm
workbench-nuxt-workflow	Ready	Preview, Comment, Open in v0	Jan 30, 2026 8:36pm
workbench-sveltekit-workflow	Ready	Preview, Comment, Open in v0	Jan 30, 2026 8:36pm
workbench-vite-workflow	Ready	Preview, Comment, Open in v0	Jan 30, 2026 8:36pm
workflow-docs	Ready	Preview, Comment, Open in v0	Jan 30, 2026 8:36pm
workflow-nest	Ready	Preview, Comment, Open in v0	Jan 30, 2026 8:36pm

[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 : 2 dependent PRs (#876 , #899 )
• Add discovered serializable classes in all context modes #874
• Ensure class serialization / deserialization only happens in the proper global context #873 👈 (View in Graphite)
• Fix class ID generation when class is bound to a variable #872
• Add discovery for custom classes with workflow serialization #859
• main

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

[Copilot]

Pull request overview

This PR tightens class serialization/deserialization so that it is always scoped to the appropriate global object, preventing leakage of class registrations between the host environment and workflow VM contexts.

Changes:

• Updated getCommonRevivers to pass the active global object into getSerializationClass, ensuring deserialization uses the correct registry for the current VM/host context.
• Simplified getSerializationClass to look up classes only on the provided global’s registry (removing the globalThis fallback) and expanded custom class serialization tests to more accurately simulate VM vs host behavior.
• Added a changeset entry for @workflow/core documenting the behavior change as a patch.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
packages/core/src/serialization.ts	Ensures class and instance revivers use the provided global when resolving class constructors, aligning deserialization with the current VM/host context.
packages/core/src/class-serialization.ts	Removes cross-context fallback in getSerializationClass and requires an explicit global, so class lookup is strictly scoped to a given global registry.
packages/core/src/serialization.test.ts	Adjusts custom class serialization tests to define/register classes separately in host and VM contexts and to assert across-context instance behavior using constructor names.
.changeset/olive-cars-run.md	Records a patch release note describing the tightened global-context scoping for class serialization/deserialization.

Comments suppressed due to low confidence (1)

packages/core/src/serialization.test.ts:1100

• These updated custom class serialization tests exercise the positive path for VM/host isolation, but there is no test that verifies the new behavior where a class registered only on the host is not deserializable inside the VM (i.e., that the old globalThis fallback is truly gone). To fully cover the new semantics described in the PR (that classes registered in one context are not accessible from another), consider adding a test in this block that registers a class only on the host, hydrates using vmGlobalThis, and asserts that deserialization fails with the expected "Class "..." not found" error.

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---

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[Copilot]

Changing getSerializationClass to require a non-optional global parameter removes the previous default of globalThis and is a breaking API change for any external callers that relied on calling this exported helper with just classId. To preserve backward compatibility (especially since this is released as a patch), consider keeping global optional with a default of globalThis while still dropping the cross-context fallback so that existing call sites outside this file continue to compile and behave as before in the host context.

Suggested change

	global: Record<string, any>
	global: Record<string, any> = globalThis