[Feature]: Add first-class support for TypeSafe AI's Jev (System One) decision model (Python) #8556

Description

Summary

Request first-class integration of TypeSafe AI's Jev model into the Microsoft Agent Framework Python SDK, similar to what LangChain (langchain-typesafe) and Pydantic AI (pydantic-ai-slim[typesafe], TypeSafeModel) already ship.

What is Jev?

Jev is a "System One" model released by TypeSafe AI on 2026-09-15. It does not generate text. You send it a piece of state (text or JSON) plus a set of typed questions, and it returns structured decisions with probabilities in a single parallel pass:

• Noul: yes/no probability in [0, 1]
• Choice: pick one option from a list you define, with probabilities
• Score: rate against an ordered scale you define

It is fast and cheap relative to frontier LLMs (vendor cites 40x–200x lower latency, $0.042 per million input tokens, output free), which makes it a good fit for the high-frequency control-plane decisions inside agent loops: routing, tool-call risk gating, scoring, escalation, model selection.

Docs: https://docs.typesafe.ai/concepts/system-one
Announcement: https://typesafe.ai/blog/introducing-system-one-models-and-jev

What problem does it solve?

Today, decisions like "is this tool call safe?", "which sub-agent should handle this?" or "is this task simple enough for a small model?" are made either by hard-coded rules or by asking the generative LLM and parsing free-form output. Jev gives typed, calibrated answers directly, with no parsing, at a fraction of the latency and cost.

Why it fits MAF

• Maps naturally onto the Python SDK's existing extension points: FunctionMiddleware (gate tool calls before execution, alongside ToolApprovalMiddleware), AgentMiddleware/ChatMiddleware (routing, model selection), AIFunction tools, and workflow executors/routers.
• Complements generative providers rather than competing with them: the LLM plans and generates, Jev decides.
• Keeps parity with other major Python agent frameworks that already have official packages.

Design note: Jev is not a chat model

Every existing provider package under python/packages/ is a chat client implementing SupportsChatGetResponse. Jev cannot be exposed that way. The proposal is a separate decision-client abstraction with adapters for middleware, tools and workflows, rather than a new chat provider.

Suggested integration surface

• New package following the existing naming convention: agent-framework-typesafe under python/packages/typesafe.
• A JevClient exposing an evaluate call that accepts state + questions and returns typed answers with probabilities.
• Adapters:
  • FunctionMiddleware factory for scoring/gating tool calls with a configurable threshold.
  • AgentMiddleware/ChatMiddleware factory for routing and model selection.
  • Helper to wrap a set of questions as an AIFunction tool.
  • Workflow executor/router for conditional edges.
• Ability to pass MAF session or workflow state as the Jev state.
• Optional confidence threshold with fallback to a generative model.

Alternatives considered

• Calling the raw TypeSafe HTTP API (POST /v1/systemone) from custom middleware or tools. Works today, but every team rebuilds the same boilerplate and type mapping.
• Community MCP servers for Jev. Usable through the hosting-mcp / MCP tool support, but adds a hop and loses the typed result surface.

Code Sample

# Desired Python experience: new package `agent-framework-typesafe`
from agent_framework import Agent
from agent_framework.azure import AzureOpenAIChatClient
from agent_framework.typesafe import JevClient, Noul, Choice, Score

jev = JevClient()  # reads TYPESAFE_API_KEY

# 1) Direct decision call (usable from tools, workflow executors, routers)
result = await jev.evaluate(
    state={"ticket": ticket_text},
    questions={
        "urgent": Noul("Does this require immediate attention?"),
        "department": Choice(
            "Which team should handle this?",
            criteria={"billing": "Payment issues", "technical": "Bugs", "other": "Everything else"},
        ),
    },
)
result.answers["urgent"].probability  # float in [0, 1]
result.answers["department"].value    # "billing" | "technical" | "other"

# 2) As FunctionMiddleware: score tool calls before execution
risk_gate = jev.function_middleware(
    question=Score("How risky is this tool call?", criteria=["safe", "needs_review", "dangerous"]),
    block_at="dangerous",
)

agent = Agent(
    client=AzureOpenAIChatClient(),
    instructions="You are a support triage agent.",
    middleware=[risk_gate],
)

Language/SDK

Python