Enforcing structured output (c.f. Pydantic) and offload to temporary variables? [design patterns?] #6758

Question

Looking for design patterns for two things that appear to be missing from the OpenCode docs and community discussions.

Background: extracting structured data (e.g., proper names + professions from a page of text, or products + UPCs from a receipt). The conventional engineering solution uses a package like Pydantic to define a structured class, and PydanticAI to feed it into a client API call, with coercion and retries managed behind the scenes:

from pydantic import BaseModel, Field
from pydantic_ai import Agent

class Employee(BaseModel):
    name: str = Field(description='the name of the individual listed on their employee card')
    role: str = Field(description="the functions the individual has permission to perform for salary")

agent = Agent(
    "my.favorite.ollama.model",
    output_type=Employee,
    instructions=('You perform information retrieval to extract verbatim text phrases from unstructured text.'),
)

async def main():
    result = await agent.run("Here is a long document of text containing...")
    print(result.output)

Question 1: How do I do the same from an OpenCode prompt without writing that code? From a prompt I can ask for structured data, but there is no guarantee the data is structured (ignoring retry mechanisms PydanticAI implements). Is that correct? And is there a pattern to store validated output to an offline file that OpenCode knows to reference later (similar to how @ works for markdown files)?

Question 2: Repeatability. Industrializing "vibe" work means capturing the sequence of tool/MCP executions from a session and exporting it as deterministic code — essentially MCP servlet cartridges with dependency requirements, replayable without the LLM (or with a small one). This also raises a distillation security consideration: create the sequence once, replay without the LLM. Is any of this native to OpenCode, or is there discussion/design patterns anywhere?

If these don't exist as native capabilities, an MCP server implementing them would be valuable; happy to work with a working group on it.

Plugins

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OpenCode version

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Steps to reproduce

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Terminal

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