v0.1.0

Added

• Protocol types for MCP specification revision 2026-07-28.
• JSON-RPC envelope parsing and writers.
• Server engine with tools, resources, resource templates, prompts, completion, pagination, multi round-trip requests and subscriptions.
• stdio transport for servers.
• Streamable HTTP transport for servers with SSE responses and header mirroring.
• Client (mcp.Client) with typed requests, progress and log callbacks, the multi round-trip driver over application hooks, and three client transports: in-memory, stdio with process management, and Streamable HTTP with header mirroring.
• OAuth 2.1 authorization client (mcp.auth.OAuthClient): protected resource and authorization server metadata discovery, pre-registered, client ID metadata document and dynamic registration, PKCE S256, resource indicators, iss validation, scope selection with step-up limits, and per-issuer credentials. The HTTP client transport answers 401 and 403 challenges with it.
• Resource server helpers (mcp.auth.ResourceServer, mcp.auth.JwtVerifier): protected resource metadata, bearer token checks with WWW-Authenticate challenges, JWT verification with HS256, ES256, RS256 and PS256, and the principal in the request context. The HTTP server serves them with the auth option.
• In-tree TLS 1.3 server (mcp.tls) with ECDSA P-256, P-384 and Ed25519 certificates, X25519, P-256 and P-384 key exchange, HelloRetryRequest, ALPN and server name indication. The HTTP transport serves HTTPS with the tls option.
• Tasks extension for servers (mcp.tasks): the tasks server option, task_support per tool, the .start_task outcome, tasks/get, tasks/update and tasks/cancel, input requests inside a task, cancellation and the -32021 gate.
• Tasks extension for clients: callTool waits for a task and answers its input requests with the hooks; callToolOrTask, getTask, updateTask, cancelTask and awaitTask give full control. The HTTP client mirrors the task id into Mcp-Name.
• stdio client process management: process groups on POSIX and a job object on Windows, shutdown escalation (SIGTERM, then SIGKILL) after limits.shutdown_grace, and restarts of a crashed server process with max_restarts.
• Client result cache (Client.Options.cache, RequestOptions.cache_mode): results with a positive ttlMs are served again until they expire, a list-changed notification arrives, or invalidateCache runs.
• Client retry of requests whose stream was lost before a response byte: RequestOptions.retry (auto, never, force) bounded by limits.max_lost_stream_retries. force reopens a listen stream after a restart.
• In-tree TLS 1.3 client (mcp.tls.connect): chain validation with a CA set, the std bundle, a pinned leaf or a self-signed policy; host name and IP address checks; CA constraints; ALPN; HelloRetryRequest; client certificates. The server can ask for client certificates (client_auth, client_trust).
• The Streamable HTTP client runs on an SDK-owned HTTP/1.1 connection (mcp.transport.http1) and uses the SDK TLS client for https (HttpClient.Options.tls).
• gRPC transport in the module mcp_grpc: a JSON-RPC tunnel over HTTP/2 (proto/mcp_zig_transport_v1.proto) with its own protobuf wire format, HPACK with the RFC 7541 tables, an HTTP/2 connection with flow control, and the gRPC server (mcp_grpc.Server) and client (mcp_grpc.Channel) transports. Metadata mirrors the HTTP headers; errors before the first message travel in the trailers with mcp-error-code and mcp-error-bin.
• Conformance fixture server and a CI job that runs the official conformance suite. The fixture server serves gRPC with --grpc-port; the CI job grpc-interop calls it from a Node http2 peer and from curl over HTTP/2.
• Comptime JSON Schema derivation from Zig types.
• JSON Schema 2020-12 subset validator. Tool arguments are checked against the input schema and structured output against the output schema.
• Build steps test, fmt, examples, docs, lint-docs, census, commit-policy, conformance-server, conformance-client, gen-bibliography, gen-dictionary, bench, check-version, changelog-section.
• Benchmarks (zig build bench) for request dispatch, HPACK decoding and the TLS handshake, with the baseline in docs/generated/bench.md and a nightly smoke run.
• Fuzz targets for every parser (zig build test --fuzz), run nightly. A certificate precheck now rejects malformed peer certificates before the std parser reads them; the first fuzz run found that the std parser reads out of bounds on truncated input.
• CI workflow with a GitHub-native Zig installation step, a consumer build through b.dependency, a nightly workflow (wiki lint, link check, ReleaseSafe matrix) and a release workflow that verifies the signed tag and publishes the changelog section.