feat(core): support valibot and other schema libraries via xsschema, not just zod

[baseballyama]

related: #143

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What is the current behavior?

We can use only zod.

What is the new behavior?

We can use valibot and other schema libraries also.

Notes for reviewers

This PR is the first step to support schema libraries other than zod in voltagent.
I plan to split the work by package, adding support for schema libraries like valibot to each package one by one.
Finally, I will update the documentation in the last PR.
This PR is not complete yet, but I would like to confirm if the direction of these changes is correct, so I am opening it as a WIP PR.

[changeset-bot]

🦋 Changeset detected

Latest commit: 0d3cfe1

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

This PR includes changesets to release 12 packages

Name	Type
@voltagent/core	Minor
@voltagent/anthropic-ai	Major
@voltagent/google-ai	Patch
@voltagent/groq-ai	Patch
@voltagent/langfuse-exporter	Major
@voltagent/postgres	Patch
@voltagent/sdk	Patch
@voltagent/supabase	Major
@voltagent/vercel-ai-exporter	Patch
@voltagent/vercel-ai	Major
@voltagent/voice	Patch
@voltagent/xsai	Major

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[omeraplak]

Hey @baseballyama , thanks a lot for the contribution! There are a few conflicts. Would you like to resolve them, or should I take care of it? Just let me know!

[baseballyama]

@omeraplak Thank you for the reminder. I plan to come back to this PR tomorrow and will rebase it then!

[tbashiyy]

@baseballyama
[just ask]
Is it difficult to use @standard-schema/spec directly instead of using xsschema ?

https://github.com/standard-schema/standard-schema/tree/main/packages/spec#how-do-i-accept-standard-schemas-in-my-library

[baseballyama]

I’m currently studying both xsschema and voltagent at the same time, making incremental changes while maintaining compatibility. While it may end up that way in the end, I’m not sure yet. That’s one of the reasons why this PR is still a work in progress.

I have other priorities at the moment, but I plan to come back to this PR right after that.

[kwaa]

[just ask] Is it difficult to use @standard-schema/spec directly instead of using xsschema ?

I also recommend using @standard-schema/spec directly if only types are needed.

The main feature of xsSchema is the toJsonSchema function, which converts any supported schema to JSON schema.

https://xsai.js.org/docs/packages-top/xsschema#tojsonschema

[baseballyama]

@kwaa I’m back to working on this PR. Since VoltAgent converts schemas like zod/valibot to JSON Schema for LLM providers, I’m convinced that xsschema is necessary. I’m currently trying to use toJsonSchema, but since VoltAgent doesn’t know the validation library in advance, I’m not sure how to call initToJsonSchemaSyncVendor. Do you have any ideas? Is the only option to have users specify the schema library name? Or should I use property names like zodSchema or valibotSchema instead of just schema so that the library can be identified?

[kwaa]

@kwaa I’m back to working on this PR. Since VoltAgent converts schemas like zod/valibot to JSON Schema for LLM providers, I’m convinced that xsschema is necessary. I’m currently trying to use toJsonSchema, but since VoltAgent doesn’t know the validation library in advance, I’m not sure how to call initToJsonSchemaSyncVendor. Do you have any ideas? Is the only option to have users specify the schema library name? Or should I use property names like zodSchema or valibotSchema instead of just schema so that the library can be identified?

You only need to use asynchronous methods. only synchronous methods need init

[baseballyama]

I need to call toJsonSchemaSync within an existing synchronous method.
I’m wondering if I have no choice but to introduce breaking changes.

e.g.

voltagent/packages/anthropic-ai/src/index.ts

Lines 82 to 88 in e0b1c7a

	toTool(tool: BaseTool): AnthropicTool {
	return {
	name: tool.name,
	description: tool.description,
	input_schema: zodToJsonSchema(tool.parameters),
	};
	}

[baseballyama]

I found this issue. It seems we might have to implement things manually for each validation library.

modelcontextprotocol/typescript-sdk#164 (comment)

[baseballyama]

Currently, @modelcontextprotocol/sdk only supports zod, so I’ve hit a roadblock. I’ve posted an idea to support standard schemas in @modelcontextprotocol/sdk. I’d appreciate it if you could share your thoughts on this from the VoltAgent team’s perspective as well.

modelcontextprotocol/typescript-sdk#164 (comment)

[omeraplak]

Currently, @modelcontextprotocol/sdk only supports zod, so I’ve hit a roadblock. I’ve posted an idea to support standard schemas in @modelcontextprotocol/sdk. I’d appreciate it if you could share your thoughts on this from the VoltAgent team’s perspective as well.

modelcontextprotocol/typescript-sdk#164 (comment)

Ah, that’s a tough blocker. Thanks for flagging it. I agree, this might take some time to land on the MCP side. Appreciate you pushing this forward

[kwaa]

btw, I also wrote the "xs" version of the MCP SDK: https://github.com/moeru-ai/xsmcp
It is based on xsSchema instead of Zod. (However, only Streamable HTTP is supported now.)

[kwaa]

I need to call toJsonSchemaSync within an existing synchronous method. I’m wondering if I have no choice but to introduce breaking changes.

You can get the vendor name from schema['~standard'].vendor - but it still requires an asynchronous init in one place.