https://github.com/agentruntimecontrolprotocol/go-sdk
Go reference SDK for ARCP (Agent Runtime Control Protocol).
https://github.com/agentruntimecontrolprotocol/go-sdk
agent-protocol agent-runtime-control-protocol agents ai-agents arcp durable-execution go golang llm mcp sdk streaming
Last synced: about 24 hours ago
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Go reference SDK for ARCP (Agent Runtime Control Protocol).
- Host: GitHub
- URL: https://github.com/agentruntimecontrolprotocol/go-sdk
- Owner: agentruntimecontrolprotocol
- License: apache-2.0
- Created: 2026-05-10T16:45:18.000Z (about 2 months ago)
- Default Branch: main
- Last Pushed: 2026-06-22T10:25:38.000Z (8 days ago)
- Last Synced: 2026-06-22T12:18:17.168Z (8 days ago)
- Topics: agent-protocol, agent-runtime-control-protocol, agents, ai-agents, arcp, durable-execution, go, golang, llm, mcp, sdk, streaming
- Language: Go
- Homepage: https://github.com/agentruntimecontrolprotocol/spec
- Size: 614 KB
- Stars: 1
- Watchers: 0
- Forks: 0
- Open Issues: 3
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- Contributing: CONTRIBUTING.md
- License: LICENSE
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README
ARCP Go SDK
Go SDK for the Agent Runtime Control Protocol (ARCP) — submit, observe, and control long-running agent jobs from Go.
Specification ·
Concepts ·
Install ·
Quick start ·
Guides ·
API reference
---
`github.com/agentruntimecontrolprotocol/go-sdk` is the Go reference implementation of [ARCP](https://github.com/agentruntimecontrolprotocol/spec/blob/main/docs/draft-arcp-1.1.md), the Agent Runtime Control Protocol. It covers both sides of the wire — the `client` package for submitting and observing jobs, the `server` package for hosting agents — along with WebSocket, stdio, and in-memory transports, OTel and HTTP-router middleware, and the `arcp` CLI, so either side can talk to any conformant peer in any language without hand-rolling the envelope, sequencing, or lease handling.
ARCP itself is a transport-agnostic wire protocol for long-running AI agent jobs. It owns the parts of agent infrastructure that don't change between products — sessions, durable event streams, capability leases, budgets, resume — and stays out of the parts that do. ARCP wraps the agent function; it does not define how agents are built, how tools are exposed (that's MCP), or how telemetry is exported (that's OpenTelemetry).
## Installation
Requires Go 1.25 or newer (matching the `go` directive in `go.mod`). The module is fetched by the Go toolchain on first build; no separate install step is required.
```sh
go get github.com/agentruntimecontrolprotocol/go-sdk@latest
```
The CLI binary lives under `cmd/arcp` and is installable on its own with `go install github.com/agentruntimecontrolprotocol/go-sdk/cmd/arcp@latest`. Optional host integrations ship as sub-packages: `middleware/nethttp`, `middleware/chi`, and `middleware/otel`.
## Quick start
Connect to a runtime, submit a job, stream its events to completion:
```go
package main
import (
"context"
"encoding/json"
"fmt"
"log"
"os"
"time"
"github.com/agentruntimecontrolprotocol/go-sdk/client"
"github.com/agentruntimecontrolprotocol/go-sdk/transport"
)
func main() {
ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
defer cancel()
t, err := transport.DialWebSocket(ctx, "wss://runtime.example.com/arcp", transport.WebSocketOptions{})
if err != nil {
log.Fatal(err)
}
cli, err := client.Connect(ctx, t, client.Options{Token: os.Getenv("ARCP_TOKEN")})
if err != nil {
log.Fatal(err)
}
defer cli.Close(ctx)
h, err := cli.Submit(ctx, client.SubmitRequest{
Agent: "data-analyzer",
Input: map[string]any{"dataset": "s3://example/sales.csv"},
})
if err != nil {
log.Fatal(err)
}
go func() {
for ev := range h.Events() {
fmt.Printf("[%s] %s\n", ev.Kind, string(ev.Body))
}
}()
res, err := h.Wait(ctx)
if err != nil {
log.Fatal(err)
}
out, _ := json.Marshal(res.Output)
log.Println("final:", res.FinalStatus, string(out))
}
```
This is the whole shape of the SDK: open a session, submit work, consume an ordered event stream, get a terminal result or error. Everything below is detail on those four moves.
## Concepts
ARCP organizes everything around four concerns — **identity**, **durability**, **authority**, and **observability** — expressed through five core objects:
- **Session** — a connection between a client and a runtime. A session carries identity (a bearer token), negotiates a feature set in a `hello`/`welcome` handshake, and is *resumable*: if the transport drops, you reconnect with a resume token and the runtime replays buffered events. Jobs outlive the session that started them. See [§6](https://github.com/agentruntimecontrolprotocol/spec/blob/main/docs/draft-arcp-1.1.md).
- **Job** — one unit of agent work submitted into a session. A job has an identity, an optional idempotency key, a resolved agent version, and a lifecycle that ends in exactly one terminal state: `success`, `error`, `cancelled`, or `timed_out`. See [§7](https://github.com/agentruntimecontrolprotocol/spec/blob/main/docs/draft-arcp-1.1.md).
- **Event** — the ordered, session-scoped stream a job emits: logs, thoughts, tool calls and results, status, metrics, artifact references, progress, and streamed result chunks. Events carry strictly monotonic sequence numbers so the stream survives reconnects gap-free. See [§8](https://github.com/agentruntimecontrolprotocol/spec/blob/main/docs/draft-arcp-1.1.md).
- **Lease** — the authority a job runs under, expressed as capability grants (`fs.read`, `fs.write`, `net.fetch`, `tool.call`, `agent.delegate`, `cost.budget`, `model.use`). The runtime enforces the lease at every operation boundary; a job can never act outside it. Leases may carry a budget and an expiry, and may be subset and handed to sub-agents via delegation. See [§9](https://github.com/agentruntimecontrolprotocol/spec/blob/main/docs/draft-arcp-1.1.md).
- **Subscription** — read-only attachment to a job started elsewhere (e.g. a dashboard watching a job a CLI submitted). A subscriber observes the live event stream but cannot cancel or mutate the job. Distinct from *resume*, which continues the original session and carries cancel authority. See [§7.6](https://github.com/agentruntimecontrolprotocol/spec/blob/main/docs/draft-arcp-1.1.md).
The SDK models each of these as first-class objects; the rest of this README shows how.
## Guides
### Sessions and resume
Open a session, negotiate features, and reconnect transparently after a transport drop using the resume token — jobs keep running server-side while you're gone.
```go
ctx := context.Background()
t, err := transport.DialWebSocket(ctx, "wss://runtime.example.com/arcp", transport.WebSocketOptions{})
if err != nil {
log.Fatal(err)
}
cli, err := client.Connect(ctx, t, client.Options{
ClientName: "resumable",
ClientVersion: "1.0.0",
Token: os.Getenv("ARCP_TOKEN"),
})
if err != nil {
log.Fatal(err)
}
defer cli.Close(ctx)
// The welcome payload carries the resume token, window, and effective
// negotiated feature set.
welcome := cli.Welcome()
fmt.Println("session:", cli.SessionID())
fmt.Println("resume window:", welcome.ResumeWindowSec, "s")
fmt.Println("features:", cli.Features())
// Subscriptions can re-anchor at a known sequence after a drop by setting
// SubscribeOptions.FromEventSeq, replaying every event with seq greater
// than that value.
```
After an unexpected drop, dial a fresh transport and present the welcome's resume block back. The runtime mints a new token, reuses the original session id, and replays buffered events with `event_seq > LastEventSeq`:
```go
prior := messages.ResumeRequest{
SessionID: cli.SessionID(),
ResumeToken: cli.Welcome().ResumeToken,
LastEventSeq: cli.HighestSeq(),
}
t2, _ := transport.DialWebSocket(ctx, url, transport.WebSocketOptions{})
cli2, err := client.Connect(ctx, t2, client.Options{
Token: os.Getenv("ARCP_TOKEN"),
Resume: &prior,
})
```
Graceful `Close` clears the resume state; only unexpected exits are resumable.
### Submitting jobs
Submit a job with an agent (optionally version-pinned as `name@version`), an input, and an optional lease request, idempotency key, and runtime limit.
```go
expires := time.Now().Add(time.Minute)
h, err := cli.Submit(ctx, client.SubmitRequest{
Agent: "weekly-report@2.1.0",
Input: map[string]string{"week": "2026-W19"},
LeaseRequest: arcp.Lease{
arcp.CapNetFetch: {"s3://reports/**"},
},
LeaseConstraints: &messages.LeaseConstraints{ExpiresAt: &expires},
IdempotencyKey: "weekly-report-2026-W19",
MaxRuntimeSec: 300,
})
if err != nil {
log.Fatal(err)
}
fmt.Println("job_id =", h.ID())
fmt.Println("effective lease =", h.Accepted().Lease)
fmt.Println("resolved agent =", h.Accepted().Agent)
```
### Consuming events
Iterate the ordered event stream — `log`, `thought`, `tool_call`, `tool_result`, `status`, `metric`, `artifact_ref`, `progress`, `result_chunk` — and optionally acknowledge progress so the runtime can release buffered events early.
```go
cli, err := client.Connect(ctx, t, client.Options{
ClientName: "ack-demo",
Token: os.Getenv("ARCP_TOKEN"),
AutoAckWindow: 32, // coalesced session.ack
AutoAckInterval: 250 * time.Millisecond,
})
if err != nil {
log.Fatal(err)
}
defer cli.Close(ctx)
h, err := cli.Submit(ctx, client.SubmitRequest{Agent: "noisy"})
if err != nil {
log.Fatal(err)
}
for ev := range h.Events() {
switch ev.Kind {
case messages.KindLog:
var b messages.LogBody
_ = json.Unmarshal(ev.Body, &b)
fmt.Println(b.Level, b.Message)
case messages.KindToolCall:
fmt.Println("→ tool", string(ev.Body))
case messages.KindMetric:
fmt.Println("metric", string(ev.Body))
case messages.KindProgress:
fmt.Println("progress", string(ev.Body))
}
// Or ack manually: _ = cli.Ack(ctx, lastSeq)
}
```
### Leases and budgets
Request capabilities, a budget, and an expiry; read budget-remaining metrics as they arrive; handle the runtime's enforcement decisions.
```go
expires := time.Now().Add(10 * time.Minute)
h, err := cli.Submit(ctx, client.SubmitRequest{
Agent: "web-research",
Input: map[string]any{"iterations": 8, "perCallUSD": 0.3},
LeaseRequest: arcp.Lease{
arcp.CapToolCall: {"search.*", "fetch.*"},
arcp.CapCostBudget: {"USD:1.00"},
},
LeaseConstraints: &messages.LeaseConstraints{ExpiresAt: &expires},
})
if err != nil {
log.Fatal(err)
}
fmt.Println("initial budget =", h.Accepted().Budget)
go func() {
for ev := range h.Events() {
if ev.Kind != messages.KindMetric {
continue
}
var m messages.MetricBody
if err := json.Unmarshal(ev.Body, &m); err != nil {
continue
}
if m.Name == "cost.budget.remaining" {
fmt.Printf("budget remaining: %.2f %s\n", m.Value, m.Unit)
}
}
}()
if _, err := h.Wait(ctx); err != nil {
// BUDGET_EXHAUSTED or LEASE_EXPIRED is never retryable.
log.Println("job ended:", err)
}
```
### Subscribing to jobs
Attach read-only to a job submitted elsewhere and observe its live stream (with optional history replay) without cancel authority.
```go
observer, err := client.Connect(ctx, t, client.Options{
ClientName: "dashboard",
Token: os.Getenv("ARCP_TOKEN"),
})
if err != nil {
log.Fatal(err)
}
defer observer.Close(ctx)
list, err := observer.ListJobs(ctx, client.ListJobsRequest{
Filter: messages.ListJobsFilter{Status: []string{"running"}},
})
if err != nil {
log.Fatal(err)
}
sub, err := observer.Subscribe(ctx, list.Jobs[0].JobID, client.SubscribeOptions{History: true})
if err != nil {
log.Fatal(err)
}
fmt.Printf("subscribed job=%s status=%s agent=%s\n", sub.JobID(), sub.CurrentStatus(), sub.Agent())
for ev := range sub.Events() {
fmt.Printf("[%s] %s\n", ev.Kind, string(ev.Body))
}
_ = sub.Close(ctx)
```
### Error handling
Catch the typed error taxonomy and respect the `retryable` flag — `LEASE_EXPIRED` and `BUDGET_EXHAUSTED` are never retryable; a naive retry fails identically.
```go
h, err := cli.Submit(ctx, client.SubmitRequest{Agent: "flaky"})
if err != nil {
log.Fatal(err)
}
if _, err := h.Wait(ctx); err != nil {
var arcpErr *arcp.Error
if errors.As(err, &arcpErr) {
switch arcpErr.Code {
case arcp.CodeLeaseExpired, arcp.CodeBudgetExhausted:
// Resubmit with a fresh lease / budget; never retry as-is.
log.Fatalf("terminal: %s", arcpErr.Code)
}
if arcp.IsRetryable(err) {
// Safe to retry with backoff (e.g. INTERNAL_ERROR, HEARTBEAT_LOST).
}
}
log.Fatal(err)
}
```
## Feature support
ARCP features this SDK negotiates during the `hello`/`welcome` handshake:
| Feature flag | Status |
|---|---|
| `heartbeat` | Supported |
| `ack` | Supported |
| `list_jobs` | Supported |
| `subscribe` | Supported |
| `lease_expires_at` | Supported |
| `cost.budget` | Supported |
| `model.use` | Supported |
| `provisioned_credentials` | Supported |
| `progress` | Supported |
| `result_chunk` | Supported |
| `agent_versions` | Supported |
## Transport
ARCP is transport-agnostic. This SDK ships a WebSocket transport (default), an NDJSON-over-stdio transport for in-process child runtimes, and an in-memory transport for tests and same-process embedders. WebSocket is the default for networked runtimes; stdio is used for in-process child runtimes. Select one by constructing the corresponding `transport.Transport` (`transport.DialWebSocket(ctx, url, opts)`, `transport.NewStdioTransport(in, out)`, or `transport.NewMemoryPair()`) and passing it to `client.Connect(ctx, t, opts)`. Host integration: `middleware/nethttp.NewHandler(srv, opts)` builds an `http.Handler` you can mount on an `*http.Server` or `http.ServeMux`; `middleware/chi.Mount(router, srv, opts)` attaches the same handler to a `chi.Router`.
## API reference
Full API reference — every type, method, and event payload — is in [`docs/`](docs/) and at .
## Versioning and compatibility
This SDK speaks **ARCP v1.1 (draft)**. The SDK follows semantic versioning independently of the protocol; the protocol version it negotiates is shown above and in `session.hello`. A runtime advertising a different ARCP MAJOR is not guaranteed compatible. Feature mismatches degrade gracefully: the effective feature set is the intersection of what the client and runtime advertise, and the SDK will not use a feature outside it.
## Contributing
See [`CONTRIBUTING.md`](CONTRIBUTING.md). Protocol questions and proposed changes belong in the [spec repository](https://github.com/agentruntimecontrolprotocol/spec); SDK bugs and feature requests belong here.
## License
Apache-2.0 — see [`LICENSE`](LICENSE).