Model Harness • AI Agent SDK

Model-family-aware agent harness, plus the test doubles for model calls.

model_harness

Model-family-aware agent harness, plus the test doubles for model calls.

Selects, by model id/family, a base/harness system-prompt fragment and a preferred file-edit format (string-replace `edit_file vs apply_patch`).

The default profile reproduces the current generic behaviour exactly, so behaviour is unchanged when no family match applies. The registry is data-driven and overridable; resolution is lazy with zero import-time cost.

Usage::

from praisonaiagents.model_harness import resolve_harness

profile = resolve_harness("claude-opus-4")
profile.base_prompt          # optional prompt fragment (str or None)
profile.preferred_edit_format  # "apply_patch" | "edit_file" | None

Testing::

from praisonaiagents import Agent from praisonaiagents.model_harness import ScriptedModel, allow_model_requests

allow_model_requests(False) # nothing in this suite may reach a provider

model = ScriptedModel([“Paris.”]) agent = Agent(instructions=”You are a geography bot.”, llm=model) assert agent.start(“Capital of France?”) == “Paris.” assert model.requests[0].system_prompt.startswith(“You are a geography bot.”)

:class:ScriptedModel returns scripted replies in order, can script a tool call followed by a final answer, records every request the agent sent, and raises :class:ScriptExhausted when the script runs out. :func:allow_model_requests is the global “no real model calls” switch.

Import

from praisonaiagents import model_harness

Constants