Thanks for your interest in improving the C# 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 C#: 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 C# 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 toolchain is pinned in global.json to the .NET SDK version listed there
(currently 10.0.203, with rollForward: latestFeature). Install a matching
.NET 10 SDK from dotnet.microsoft.com/download, then clone and
restore. Package versions are managed centrally via Directory.Packages.props,
so dotnet restore is the only bootstrap step.
git clone https://github.com/agentruntimecontrolprotocol/csharp-sdk.git
cd csharp-sdk
dotnet restore ARCP.slnx
dotnet build ARCP.slnxTwo layers must pass before a PR merges:
-
Unit tests — this SDK's own suite:
dotnet test ARCP.slnx -
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. The conformance suite in
tests/Arcp.ConformanceTests/pairsArcp.ClientwithArcp.RuntimeoverMemoryTransportso every fact runs against the in-tree reference implementation; run it on its own withdotnet test tests/Arcp.ConformanceTests/Arcp.ConformanceTests.csproj, and seeCONFORMANCE.mdfor the spec-section-to-test map.
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.
Formatting, analyzers, and style are enforced as part of the build:
Directory.Build.props sets TreatWarningsAsErrors=true and
EnforceCodeStyleInBuild=true, so analyzer and StyleCop diagnostics fail the
build. CI also runs dotnet format --verify-no-changes, so format locally
before pushing.
dotnet format ARCP.slnx
dotnet format ARCP.slnx --verify-no-changes
dotnet build ARCP.slnx --configuration ReleaseMatch 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. Pushing a v* tag triggers the publish
GitHub Actions workflow, which packs every project under src/ and pushes all
eight packages (Arcp, Arcp.Core, Arcp.Client, Arcp.Runtime,
Arcp.AspNetCore, Arcp.Otel, Arcp.Hosting, Arcp.Cli) to
nuget.org. 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.