Thanks for your interest in improving the Rust SDK for ARCP. This document covers how to report issues, propose changes, and get a change merged.
By participating you agree to the Code of Conduct.
ARCP is two things in two places, and a change belongs to exactly one of them:
- The protocol — the wire format, message semantics, lease rules, error taxonomy, feature flags. These live in the specification repository. If your idea changes what goes on the wire or what a conformant runtime must do, it is a spec change — open it there, not here. This SDK implements the spec; it does not define it.
- This SDK — how the protocol is expressed idiomatically in Rust: bugs, ergonomics, performance, missing-but-specified features, docs, tests. Those belong here.
When in doubt, open an issue here and we'll redirect if it's really a protocol question.
A change to this SDK must keep it a faithful client of ARCP v1.1 (draft). Concretely:
- Don't invent wire behavior. No envelope fields, event kinds, error codes, or feature flags that the spec doesn't define. If you need one, it's a spec proposal first.
- Negotiate honestly. Only advertise a feature flag in
session.helloonce the SDK actually implements it. The feature matrix in the README must match what the code negotiates — a row markedSupportedis a promise. - Respect the semantics. Sequence numbers stay gap-free and monotonic;
LEASE_EXPIREDandBUDGET_EXHAUSTEDstay non-retryable; the effective feature set is the intersection of client and runtime advertisements. Tests must not paper over a semantic the spec requires. - Stay layered. This SDK controls runtimes. It does not expose tools (that's MCP) or export telemetry (that's OpenTelemetry). PRs that blur those layers will be asked to move the logic out.
Open an issue with: the SDK version and Rust version, the runtime you
connected to, a minimal reproduction (the smallest program that triggers it),
what you expected, and what happened. A failing test is the best possible bug
report. Wire-level traces (the envelopes exchanged) help enormously for protocol
behavior — redact any auth.token or provisioned-credential value first.
For anything beyond a small fix, open an issue describing the problem before writing code, so we can agree on the approach. Small, focused PRs review faster than large ones; if a change is big, say so early and we'll help break it down.
The crate targets the toolchain pinned in rust-toolchain.toml
(stable with rustfmt, clippy, and rust-src) and an MSRV of 1.88 as
declared in Cargo.toml. Install Rust via
rustup; cargo and the pinned components are then
provisioned automatically on first build.
git clone https://github.com/agentruntimecontrolprotocol/rust-sdk.git
cd rust-sdk
cargo build --all-targets --all-featuresTwo layers must pass before a PR merges:
-
Unit tests — this SDK's own suite:
cargo test --all-features -
Conformance — the SDK's behavior against the reference runtime. New protocol-facing code (session negotiation, event sequencing, lease handling, error mapping) needs a test that exercises the real exchange, not a mock that assumes the answer. Integration tests under
tests/drive the in-process runtime end to end; to point them at an out-of-process runtime, start one withcargo run -- serve --bearer secret-token --principal alice@example.comand connect the WebSocket transport atws://127.0.0.1:8765. SeeCONFORMANCE.mdfor the section-by-section coverage matrix.
CI runs both on every PR. A PR that changes which feature flags the SDK negotiates must also update the README feature matrix in the same change.
Format, lint, and verify with the same commands CI runs:
cargo fmt --all -- --check
cargo clippy --all-targets --all-features -- -D warnings
cargo check --all-targets --all-featuresMatch the surrounding code. Public API changes need doc comments and an entry in the changelog. Prefer clarity over cleverness in a library others build on.
-
Write focused commits with present-tense, imperative subjects (
add result_chunk reassembly, notadded/adds). -
Reference the issue a PR closes (
Closes #123). -
Keep the PR description honest about scope and any spec sections touched.
-
Rebase on the default branch and ensure CI is green before requesting review.
-
Sign off your commits to certify the Developer Certificate of Origin:
git commit -s -m "your message"
Releases are cut by maintainers. The crate is published to
crates.io by a maintainer running
cargo publish after tagging the release commit; cargo publish --dry-run is
part of the pre-release checklist. The SDK is versioned with semantic
versioning independently of the protocol version it speaks; a protocol version
bump is noted in the changelog when the negotiated ARCP version changes.
By contributing, you agree that your contributions are licensed under the project's Apache-2.0 license.