Development

You need Rust 1.99 or newer, a C toolchain (build-essential) and uv.

cargo test --workspace                      # Rust tests
uv sync                                     # venv + dev tools; builds the extension
uv run pytest                               # Python tests
uv run maturin develop                      # rebuild after changing Rust code
cargo run -p k9-http --example phases      # print phase timings against the test server
cargo run -p k9-testserver                  # standalone target on :8080 (HTTP) and :8443 (HTTPS)
cargo bench -p k9-metrics                   # hot-path benchmarks (also k9-core, k9-http)

Benchmark results and the machine they ran on are in docs/benchmarks.md.

Layout:

Path	Role
crates/k9-core	Plan model, engine (executors, VUs, run controller), the Script trait that Python plugs into
crates/k9-http	HTTP client with k6's per-phase timings (blocked, connecting, TLS, sending, waiting, receiving)
crates/k9-metrics	k6's metrics (Counter, Gauge, Rate, Trend on HDR histograms), tag interning, per-thread recording, aggregation
crates/k9-output	The end-of-test summary, the HTML report and the --out outputs
crates/k9-cli	The k9 command (library and standalone binary)
crates/k9-grpc	The manager ↔ worker protocol over gRPC (proto/k9/worker/v1/worker.proto)
crates/k9-py	PyO3 bindings, built as k9._native: the script host and the bridge to the asyncio loop
crates/k9-tui	The live dashboard (k9 run --tui), on ratatui
crates/k9-testserver	Target server for testing K9 itself: delays, error rates, stalls, big bodies
python/k9	The Python package
docs	This documentation (mkdocs) and the landing page

Continuous integration

Pull requests run the tests on Linux, macOS and Windows (Python 3.10 and 3.14, and the minimum supported Rust).