atif 1.7.0a0

Pydantic models for the Agent Trajectory Interchange Format (ATIF v1.7).

atif

Pydantic models for the Agent Trajectory Interchange Format (ATIF), a standardized JSON schema for logging the complete interaction history of autonomous LLM agents — user messages, agent responses, tool calls, observations, metrics, and embedded subagent trajectories. Implements ATIF v1.7.

Install

pip install atif

Usage

from atif import Trajectory

data = {
    "schema_version": "ATIF-v1.7",
    "agent": {"name": "my-agent", "version": "1.0.0", "model_name": "claude-sonnet-4-6"},
    "steps": [
        {"step_id": 1, "source": "user", "message": "What time is it?"},
        {
            "step_id": 2,
            "source": "agent",
            "message": "Let me check.",
            "tool_calls": [
                {"tool_call_id": "c1", "function_name": "now", "arguments": {}}
            ],
            "observation": {
                "results": [{"source_call_id": "c1", "content": "2026-05-16T12:00:00Z"}]
            },
            "metrics": {"prompt_tokens": 120, "completion_tokens": 18},
        },
    ],
}

trajectory = Trajectory.model_validate(data)
print(trajectory.steps[1].tool_calls[0].function_name)  # "now"
print(trajectory.to_json_dict(exclude_none=True))

Validation enforces the ATIF rules: sequential step_ids, ISO 8601 timestamps, agent-only fields gated on source == "agent", tool-call / observation correlation, embedded-subagent trajectory_id uniqueness, and ContentPart text/image XOR.

Versioning

atif's MAJOR.MINOR tracks the ATIF RFC version it implements (1.7.x ⇔ ATIF v1.7); PATCH is reserved for library-only fixes. Because the ATIF RFC occasionally introduces breaking changes on a MINOR bump (e.g. v1.7's SubagentTrajectoryRef resolution change), a MINOR bump of this library may be breaking too — pin to atif~=1.7.0 if you need to stay on a single ATIF version.