pip install handoffkit

What It Is

HandoffKit is a lightweight Python framework for building multi-agent AI workflows where agents pass structured state instead of free-text summaries.

Most multi-agent demos do this:

Agent A -> "Here is roughly what happened..." -> Agent B

HandoffKit does this:

Architect
  task: "Build a calculator CLI"
  decisions: ["Use argparse", "Keep operations pure"]
  files: ["calculator.py", "test_calculator.py"]
  next_steps: ["Implement CLI", "Run pytest"]
        |
        v
Coder
  receives HandoffState, not a vague paragraph
        |
        v
Tester
  receives decisions, files, errors, and test evidence

That makes agent workflows easier to inspect, test, replay, and improve.

What 0.8.0 Adds

HandoffKit 0.8.0 prepares the package for the road to 1.0 with traceable, replayable workflow evidence:

• RunTrace, TraceStep, and TraceEvent for serializable run traces,
• FileTraceStore for local trace storage,
• ReplayRunner and ReplaySummary for replay inspection without re-execution,
• write_report_files() and load_report_json() for report IO,
• HandoffState.json_schema(), ValidationReport.json_schema(), and RunTrace.json_schema(),
• configurable HandoffQualityEvaluator(min_score=..., required_metrics=...),
• CLI commands for doctor, api, demo-trace, demo-replay, and validate-report,
• stable API documentation for the path to 1.0.

What 0.7.0 Adds

HandoffKit 0.7.0 adds reusable validation and quality layers for mature multi-agent workflows:

• ValidationIssue and ValidationReport for reusable contract reports,
• HandoffStateValidator, StructuredOutputValidator, and ToolSchemaValidator,
• validate_report(...) helpers while keeping existing validate() behavior,
• HandoffQualityEvaluator with deterministic handoff quality scoring,
• quality metrics for completeness, clarity, actionability, traceability, and error awareness,
• provider-native tool schemas for handoffkit, openai, and anthropic,
• provider-style tool call parsing with call ID preservation,
• provider_adapter support in Agent.run_with_tools(...),
• offline quality, validator, and provider-format demos with JSON/Markdown reports.

What 0.6.0 Adds

HandoffKit 0.6.0 adds structured outputs and provider-neutral tool adapters:

• StructuredOutputSchema for lightweight schemas without Pydantic,
• StructuredOutputResult for validated model output reports,
• JsonOutputParser for clean, fenced, or embedded JSON,
• OutputRepairer for simple JSON cleanup,
• Agent.run_structured() for schema-guided agent runs,
• ProviderCapabilities for serializable provider feature flags,
• ProviderToolAdapter for normalizing provider tool schemas and calls,
• ToolCallParser for provider-style tool call payloads,
• provider_json mode in Agent.run_with_tools(),
• structured demos and tests that run without API keys.

What 0.5.0 Added

HandoffKit 0.5.0 adds reusable workflow building blocks:

• RecipeStep for one named workflow step,
• Recipe for reusable agent workflows,
• RecipeRunner and RecipeRunResult for execution and reports,
• WorkflowTemplate for common workflow patterns,
• Extension and ExtensionRegistry for safe local extension bundles,
• built-in recipe factories,
• recipe and extension demos,
• Markdown/JSON recipe reports.

This keeps HandoffKit general. Repo agents, research agents, coding agents, and business agents can be built on top of HandoffKit without turning the core into a GitHub- or repository-specific package.

What 0.4.0 Added

HandoffKit 0.4.0 adds a lightweight memory and project context engine:

• MemoryItem, MemoryStore, and JsonMemoryStore for structured memory,
• ProjectIndexer for scanning local project files,
• ContextRetriever for deterministic keyword retrieval,
• ContextPack for bundling relevant files and memories,
• Agent.run_with_context() for context-aware agent runs,
• HandoffState.context_refs so agents can pass explicit context references.

No vector database. No heavy dependency stack. Just transparent, inspectable context for agent workflows.

What 0.3.0 Added

HandoffKit 0.3.0 adds a real tool execution loop:

• ToolCall and ToolResult models,
• ToolRegistry for registering and executing tools by name,
• Agent.run_with_tools() for structured tool loops,
• deterministic local tool execution with EchoProvider,
• provider JSON tool-call mode for fake or real providers,
• basic safety checks for shell and write operations,
• ToolExecutionReport with JSON and Markdown export.

Why HandoffKit?

Multi-agent systems break when context handoffs are vague. One agent makes a decision, another agent never sees it. One agent finds an error, the next agent gets only a polished summary. Files, constraints, and validation evidence vanish.

HandoffKit gives you:

• Agent: a small role-based agent abstraction.
• HandoffState: a JSON-friendly contract between agents.
• HandoffProtocol: protocol modes for different transfer styles.
• Team: sequential multi-agent execution.
• tool: typed Python tools with schema metadata.
• EchoProvider: deterministic local provider for tests and demos.
• OllamaProvider: local Ollama integration.
• OpenAIProvider: OpenAI and OpenAI-compatible APIs.

Core Concept

from handoffkit import Agent, HandoffProtocol

architect = Agent("Architect", "Create implementation plans.")
coder = Agent("Coder", "Implement from structured handoff state.")

protocol = HandoffProtocol(mode="hybrid_state")

state = protocol.transfer(
    from_agent=architect,
    to_agent=coder,
    task="Create a small Python CLI calculator with tests.",
    summary="Build a dependency-free CLI with pytest coverage.",
    decisions=["Use argparse.", "Keep calculator operations pure."],
    important_files=["calculator.py", "test_calculator.py"],
    next_steps=["Implement code.", "Run pytest."],
)

state.validate()
print(state.to_json())

Protocols

Quickstart

from handoffkit import Agent

agent = Agent(
    name="Planner",
    role="Create concise implementation plans.",
)

print(agent.run("Create a plan for a Python CLI app with tests."))

No API key required. By default, HandoffKit uses EchoProvider, so examples and tests run locally and deterministically.

Tool Schema Example

from handoffkit import tool


@tool
def add(a: int, b: int) -> int:
    """Add two numbers."""
    return a + b


print(add.to_schema())
print(add.run(a=2, b=3))

Output:

{
    "name": "add",
    "description": "Add two numbers.",
    "parameters": {
        "type": "object",
        "properties": {
            "a": {"type": "integer"},
            "b": {"type": "integer"},
        },
        "required": ["a", "b"],
    },
}

Tool Execution Loop

Register Python tools, let an agent create structured ToolCall objects, execute them through a ToolRegistry, and receive structured ToolResult objects.

from handoffkit import Agent
from handoffkit.tools.filesystem import list_files, read_file

agent = Agent(
    name="FileAgent",
    role="Use tools to inspect files.",
    tools=[read_file, list_files],
)

result = agent.run_with_tools("read file README.md")
print(result.final_output)
print(result.tool_results)

There are two modes:

• Deterministic/local mode: with EchoProvider, HandoffKit handles simple tasks such as read file README.md, list files ., write file ..., or run command .... This is honest local automation, not hidden AI reasoning.
• Provider JSON mode: if a provider returns JSON with tool_calls, HandoffKit executes those tools and feeds results into the next step until the provider returns {"final": "..."} or max_steps is reached.

Provider tool-call JSON:

{
  "tool_calls": [
    {
      "tool_name": "read_file",
      "arguments": {
        "path": "README.md"
      }
    }
  ],
  "final": null
}

Safety:

• dangerous shell commands such as rm -rf, del /s, format, shutdown, reboot, mkfs, and diskpart are blocked;
• when require_approval=True, write and shell tools return approval_required instead of executing.

Structured Outputs + Provider Tool Adapters

Structured outputs matter because multi-agent workflows need machine-checkable contracts, not only polished prose. HandoffKit can ask a provider for JSON, parse common response shapes, validate the result, and perform small safe repairs such as removing Markdown fences or trailing commas.

from handoffkit import Agent, StructuredOutputSchema

schema = StructuredOutputSchema(
    name="TaskSummary",
    fields={
        "title": str,
        "summary": str,
        "success": bool,
    },
    required=["title", "summary", "success"],
)

agent = Agent(name="Reporter", role="Return structured task summaries.")
result = agent.run_structured("Summarize the task.", schema=schema)

print(result.data)
print(result.to_markdown())

Agent.run_structured() sends schema instructions to the provider, parses the response with JsonOutputParser, validates it with StructuredOutputSchema, and can use OutputRepairer for simple JSON mistakes. It works with fake or local providers, so normal tests do not require API keys.

Provider tool adapters keep tool calling provider-agnostic:

from handoffkit import ProviderToolAdapter, ToolRegistry, tool

@tool
def read_file(path: str) -> str:
    """Read a file."""
    return f"read:{path}"

adapter = ProviderToolAdapter()
provider_tools = adapter.tools_to_provider_format([read_file])
tool_calls = adapter.parse_tool_calls({
    "tool_calls": [
        {
            "function": {
                "name": "read_file",
                "arguments": "{\"path\":\"README.md\"}",
            }
        }
    ]
})

registry = ToolRegistry([read_file])
results = [registry.execute(call) for call in tool_calls]

The internal format stays ToolCall(tool_name="read_file", arguments={...}) whether a provider returns HandoffKit JSON or function-style tool calls. This is provider-neutral by design; HandoffKit does not require any external SDK for normal tests.

Handoff Quality Metrics

Quality checks are deterministic and offline. They help compare handoff states without calling a provider or judging prose with another model.

from handoffkit import HandoffQualityEvaluator, HandoffState

state = HandoffState(
    task="Create a Python CLI calculator.",
    from_agent="Architect",
    to_agent="Coder",
    summary="Build an argparse calculator with pure operations and tests.",
    decisions=["Use argparse.", "Keep operations pure."],
    important_files=["calculator.py", "test_calculator.py"],
    next_steps=["Implement calculator.py", "Run pytest -q"],
    context_refs=["README.md#real-task-demo"],
    metadata={"errors_checked": True},
)

report = HandoffQualityEvaluator().evaluate(state)
print(report.score, report.grade)
print(report.to_markdown())

Metrics:

Contract Validators

Validators return ValidationReport objects that can be serialized, rendered as Markdown, or raised as exceptions. Existing APIs stay compatible: HandoffState.validate() still returns self or raises HandoffValidationError, and StructuredOutputSchema.validate() still returns the input dictionary or raises OutputValidationError.

from handoffkit import (
    HandoffStateValidator,
    StructuredOutputSchema,
    StructuredOutputValidator,
    ToolSchemaValidator,
    tool,
)

@tool
def add(a: int, b: int) -> int:
    """Add two integers."""
    return a + b

schema = StructuredOutputSchema(
    name="Plan",
    fields={"title": str, "ready": bool},
    required=["title", "ready"],
)

print(StructuredOutputValidator().validate(schema, {"title": "Demo", "ready": True}).to_json())
print(ToolSchemaValidator().validate(add).to_markdown())

Provider Tool Formats

ProviderToolAdapter can render tools as HandoffKit, OpenAI function-style, or Anthropic tool_use schemas. It also parses provider-native tool call payloads back into HandoffKit ToolCall objects.

from handoffkit import ProviderToolAdapter, tool

@tool
def read_file(path: str) -> str:
    """Read a file."""
    return f"read:{path}"

openai_adapter = ProviderToolAdapter(provider_format="openai")
anthropic_adapter = ProviderToolAdapter(provider_format="anthropic")

print(openai_adapter.tools_to_provider_format([read_file]))
print(anthropic_adapter.tools_to_provider_format([read_file]))

calls = openai_adapter.parse_tool_calls({
    "tool_calls": [
        {
            "id": "call_123",
            "type": "function",
            "function": {"name": "read_file", "arguments": "{\"path\":\"README.md\"}"},
        }
    ]
})
print(calls[0].tool_name, calls[0].arguments, calls[0].call_id)

Replayable Workflows

Run traces turn team, recipe, and tool execution reports into durable evidence. Replay does not call providers or tools again; it inspects a saved trace.

from handoffkit import Agent, HandoffProtocol, RunTrace, Team

team = Team(
    agents=[Agent("Planner", "Plan."), Agent("Reviewer", "Review.")],
    protocol=HandoffProtocol(mode="hybrid_state"),
)

result = team.run("Prepare a release checklist.")
trace = RunTrace.from_team_result(result)

print(trace.to_json())
print(trace.to_markdown())

Run Traces

RunTrace can be created from TeamRunResult, RecipeRunResult, and ToolExecutionReport.

from handoffkit import FileTraceStore, ReplayRunner, RunTrace

trace = RunTrace.from_team_result(result, name="release-checklist")
path = FileTraceStore("traces").save(trace)
loaded = FileTraceStore("traces").load(path)
summary = ReplayRunner(loaded).summary()

print(summary.to_markdown())

Report Files

Any report object with to_json(), to_markdown(), or to_dict() can be written consistently:

from handoffkit import write_report_files

json_path, markdown_path = write_report_files(trace, "trace_demo")

CLI Doctor

handoffkit doctor
handoffkit api
handoffkit demo-trace
handoffkit demo-replay
handoffkit validate-report reports/trace_demo.json

doctor runs local package diagnostics only. It does not make network calls and does not inspect secrets.

Stable API Surface

The following APIs are treated as 1.0 candidates:

• Agent, Team, HandoffState, HandoffProtocol,
• Tool, ToolCall, ToolResult, ToolRegistry,
• Recipe, RecipeStep, RecipeRunner, RecipeRunResult,
• ValidationReport, HandoffQualityReport,
• ProviderToolAdapter,
• RunTrace, ReplayRunner.

See docs/API_STABILITY.md and docs/ROAD_TO_1_0.md.

Memory + Project Context

HandoffKit can store durable project decisions, index local files, retrieve relevant context, and hand explicit references from one agent to the next.

from handoffkit import (
    Agent,
    ContextPack,
    ContextRetriever,
    JsonMemoryStore,
    ProjectIndexer,
)

memory = JsonMemoryStore("examples/output/memory.json")
memory.add(
    "Calculator CLI should use argparse and pure functions.",
    kind="decision",
    tags=["calculator", "cli"],
)

documents = ProjectIndexer(".").index()
retriever = ContextRetriever(documents)
matches = retriever.search("calculator argparse tests", limit=3)

context = ContextPack(
    query="Create a calculator CLI implementation plan.",
    documents=matches,
    memories=memory.search("calculator cli", limit=3),
)

agent = Agent("Architect", "Create concise implementation plans.")
result = agent.run_with_context(
    "Create a concise architecture plan for a Python CLI calculator.",
    context=context,
    memory=memory,
)

print(result.final_output)
print(context.to_markdown())

Run the included demos:

python examples/memory_demo.py
python examples/project_context_demo.py
python examples/context_handoff_demo.py

Recipes + Extension API

Recipes make agent workflows reusable. Instead of wiring the same planner, executor, reviewer, tools, context, and memory flow by hand in every script, you can define a Recipe once and run it with RecipeRunner.

from handoffkit import Agent, Recipe, RecipeRunner, RecipeStep

planner = Agent(name="Planner", role="Plan the task.")
executor = Agent(name="Executor", role="Execute the plan.")
reviewer = Agent(name="Reviewer", role="Review the result.")

recipe = Recipe(
    name="plan-execute-review",
    description="A reusable three-step workflow.",
    steps=[
        RecipeStep(name="plan", agent=planner, task="Create a plan."),
        RecipeStep(name="execute", agent=executor, task="Execute the plan."),
        RecipeStep(name="review", agent=reviewer, task="Review the output."),
    ],
)

result = RecipeRunner(recipe).run()
print(result.to_markdown())

Templates create common workflow shapes:

from handoffkit import Agent, WorkflowTemplate

recipe = WorkflowTemplate.sequential(
    name="simple-workflow",
    agents=[
        Agent("Architect", "Plan."),
        Agent("Coder", "Build."),
        Agent("Tester", "Test."),
    ],
    task="Build a small calculator.",
)

Extensions bundle recipes and tools safely:

from handoffkit import Extension, ExtensionRegistry

registry = ExtensionRegistry()
registry.register(
    Extension(
        name="coding",
        description="Local coding workflows.",
        version="0.1.0",
        recipes=[recipe],
        tools=[],
    )
)

print([recipe.name for recipe in registry.recipes()])

HandoffKit does not ship Git/GitHub APIs as core primitives. A repository agent can be built as an extension or recipe using HandoffKit's general tools: structured state, memory, context packs, recipes, and extension registries.

Real Task Demo

HandoffKit includes a reproducible real task demo:

python examples/real_task_calculator.py

It runs this workflow:

Architect -> Coder -> Tester -> Reporter

Task:

Create a tiny Python CLI calculator with add, subtract, multiply and divide
operations, plus tests.

The demo creates a real generated project:

examples/output/calculator_cli/
  calculator.py
  test_calculator.py
  README.md

It also writes reproducibility reports:

reports/real_task_calculator.md
reports/real_task_calculator.json

The generated project is tested with pytest, and the report captures command, cwd, return code, stdout, stderr, files created, provider used, model used, and handoff flow.

Providers

Local deterministic provider

from handoffkit import Agent

agent = Agent("Planner", "Plan work.")
print(agent.run("Prepare a package release."))

Ollama

ollama pull llama3.1
ollama serve
python examples/ollama_agent.py --model llama3.1

OpenAI-compatible APIs

$env:OPENAI_API_KEY="..."
$env:OPENAI_BASE_URL="https://api.freemodel.dev/v1"
$env:OPENAI_MODEL="gpt-4o-mini"
python examples/freemodel_openai_compatible.py

Optional real API tests are skipped unless explicitly enabled:

$env:HANDOFFKIT_RUN_API_TESTS="1"
$env:OPENAI_API_KEY="..."
$env:OPENAI_BASE_URL="https://api.freemodel.dev/v1"
$env:OPENAI_MODEL="gpt-4o-mini"
pytest tests_api -q

Use temporary or scoped provider tokens. Do not commit API keys.

CLI

handoffkit --version
handoffkit demo
handoffkit demo-recipe
handoffkit demo-extension
handoffkit demo-structured
handoffkit demo-provider-tools
handoffkit demo-quality
handoffkit demo-validators
handoffkit demo-provider-formats
handoffkit doctor
handoffkit api
handoffkit demo-trace
handoffkit demo-replay
handoffkit validate-report reports/trace_demo.json

Examples

python examples/simple_agent.py
python examples/handoff_demo.py
python examples/coding_team.py
python examples/tool_schema_demo.py
python examples/tool_execution_demo.py
python examples/fake_provider_tool_call_demo.py
python examples/structured_output_demo.py
python examples/provider_tool_adapter_demo.py
python examples/handoff_quality_demo.py
python examples/contract_validation_demo.py
python examples/provider_tool_formats_demo.py
python examples/trace_demo.py
python examples/replay_demo.py
python examples/provider_matrix_demo.py
python examples/structured_recipe_demo.py
python examples/recipe_demo.py
python examples/coding_review_recipe.py
python examples/extension_demo.py
python examples/memory_demo.py
python examples/project_context_demo.py
python examples/context_handoff_demo.py
python examples/real_task_calculator.py

Development

git clone https://github.com/DaosPath/handoffkit.git
cd handoffkit
pip install -e ".[dev]"

Run checks:

ruff check .
pytest -q
python -m build
python -m twine check dist/*

Publishing

Build and validate:

python -m build
python -m twine check dist/*

Upload to TestPyPI first:

python -m twine upload --repository testpypi dist/*

Upload to PyPI only after TestPyPI install verification:

python -m twine upload dist/*

Inspiration

HandoffKit is inspired by the research and reproducibility repository DaosPath/state-transfer-protocols, especially its comparison of natural, compressed, hybrid_min, and hybrid_state handoff protocols for multi-agent workflows.

HandoffKit is a developer library, not a copy of that repository.

Roadmap

• richer memory persistence adapters,
• broader tool schema coverage,
• provider-specific integration examples,
• benchmark-inspired quality comparisons,
• API freeze and migration guide for 1.0,
• memory integrations,
• project context retrieval,
• benchmark-inspired examples,
• multi-agent workflow templates.

License

MIT.