Rewyn

Build. Run. Replay. Improve AI.

Agents fail in ways tests do not catch. They worked yesterday, they answer differently today, and the run that proves it is gone.

Rewyn records every run so you can go back to it. Every primitive emits a structured event, so any run can be replayed exactly, diffed against another, scored, and turned into a regression test — long after it happened.

It is provider-agnostic, framework-independent, and local-first: no account, no API key, no network.

from rewyn import Agent

agent = Agent(model="openai:gpt-5")
result = agent.run("Research the latest electric vehicle market")

Every primitive emits structured execution events. Every run is recorded locally under .rewyn/, can be inspected, exported, replayed, diffed and turned into a regression test.

from rewyn.evaluation.dataset import Dataset
from rewyn.evaluation.metrics import exact_match
from rewyn.evaluation.regression import run_regression
from rewyn.replay.replay import replay

# Reproduce the run exactly, with no provider call.
replay(result.run_id)

# A production run becomes a regression test.
dataset = Dataset(name="critical")
dataset.add_run(result.run_id)
report = run_regression(dataset, agent, evaluators=[exact_match()])
print(report.render())

See it work

uv run python -m demo

A minute, offline, no API key. A support agent that works; the same desk built full stack with retrieval, memory, MCP, a subagent, a graph and a hostile customer email that cannot override policy; the same agent giving a different answer the next day; and the diff, replay and release gate that catch it. See demo/.

Install

pip install rewyn                # core, provider agnostic
pip install "rewyn[openai]"      # OpenAI adapter
pip install "rewyn[anthropic]"   # Anthropic adapter
pip install "rewyn[google]"      # Google Gemini adapter
pip install "rewyn[mcp]"         # Model Context Protocol client/server
pip install "rewyn[redis]"       # shared memory and checkpoints
pip install "rewyn[s3]"          # S3-compatible object storage
pip install "rewyn[search]"      # Elasticsearch / OpenSearch retrieval
pip install "rewyn[ui]"          # the local console (rewyn ui)
pip install "rewyn[all]"         # everything

Rewyn is local-first: no account, no cloud, no Rewyn API key.

CLI

rewyn init | runs | inspect | replay | diff | eval | test | datasets
        | manifest | drift | export | import | doctor | skills | mcp | agents
        | ui | login | logout | sync

Console

pip install "rewyn[ui]"
rewyn ui                          # http://127.0.0.1:4400

An execution debugger for your own runs: the timeline of everything an agent did, the execution graph, and a context inspector that shows which item came from where, at which version, and how much of the budget it cost. No account and no cloud -- it reads the .rewyn/ you already have. The cloud console serves the same screens over a team's runs. See docs/ui.md.

Cloud (optional)

Rewyn is complete without it, and always will be. When a team wants shared runs, centralised datasets and evaluation history that outlives one laptop, the SDK syncs to a hosted service:

rewyn login --endpoint https://api.rewyn.dev --key rw_...
rewyn sync

The client half of that protocol is here and open source, so what a deployment speaks stays inspectable. Uploads retry, buffer locally when the service is unreachable, and never raise into your application. See docs/cloud.md and https://rewyn.dev.

Development

make install   # uv sync with all extras
make check     # ruff + mypy --strict + pytest

Documentation

docs/ has a page per subsystem, each with a concept, a minimal example, a production example, an API pointer and the failure modes. Start with getting started.

The golden demo is one application that uses every subsystem and then replays, diffs, evaluates and gates itself, offline:

uv run python -m examples.enterprise_research_agent

Rewyn also works alongside what you already run: Redis, PostgreSQL with pgvector, S3, Elasticsearch, OpenTelemetry, other agent frameworks, and other agents over an agent-to-agent interface. See integrations.

See docs/ for the subsystem guides, and CONTRIBUTING.md if you would like to help.

License

Apache-2.0.