DeepSeek Harness Go SDK

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Go SDK for driving DeepSeek Harness. The SDK starts the Harness runtime as a subprocess and speaks the line-delimited JSON-RPC 2.0 protocol over stdio. It is a clean-room Go implementation of the protocol and mirrors the layering and activity semantics of the upstream Python SDK.

Requirements

• Go 1.26 or newer.
• macOS arm64/x64, Linux amd64/arm64, or Windows amd64 when using the bundled runtime downloader.
• An explicit DSHHome or non-empty DSH_HOME environment variable.
• A DEEPSEEK_API_KEY environment variable, unless the selected profile uses another credential path or a local model proxy.

Install

go get github.com/theoneLee/deepseek-harness-sdk-go

The SDK targets the single-file runtime published by the DeepSeek Harness project. With no explicit executable, the first Start or Run resolves the matching platform wheel from a PyPI-style index, verifies SHA-256, extracts it into a cache, and reuses it on later starts. The default target is runtime 0.1.5-alpha.1, corresponding to upstream tag dsh-v0.1.5-alpha.1. The matching public runtime wheel must be available before automatic download can start this version; use DSHBin or RuntimeIndexURL when consuming a private or pre-publication wheel.

Quick start

package main

import (
	"fmt"

	deepseekharness "github.com/theoneLee/deepseek-harness-sdk-go"
)

func main() {
	harness := deepseekharness.NewDeepSeekHarness(deepseekharness.DeepSeekHarnessConfig{
		DSHHome: "/absolute/path/to/dsh-home",
	})
	defer harness.Close()

	result, err := harness.Run("Say hi.")
	if err != nil {
		panic(err)
	}
	fmt.Println(result.FinalResponse)
}

DeepSeekHarness starts lazily and keeps the subprocess alive across runs. Always call Close when the harness is no longer needed so the runtime is reaped promptly.

Configuration

harness := deepseekharness.NewDeepSeekHarness(deepseekharness.DeepSeekHarnessConfig{
	Provider:   "deepseek-official",
	Model:      "deepseek-v4-flash",
	ReasoningEffort: "max",
	MaxTokens:  49_152,
	DSHHome:    "/absolute/path/to/dsh-home",
	Profile:    "sdk",
	Patches:    []string{"/absolute/path/to/patch.yml"},
})
defer harness.Close()

The runtime inherits the parent environment. Env overlays it for the child; BaseURL and APIKey are convenience fields for DEEPSEEK_BASE_URL and DEEPSEEK_API_KEY. CWD is sent in the initialize payload; RuntimeCWD controls the subprocess working directory. DSHHome overrides the child DSH_HOME; without it, the child must inherit a non-empty DSH_HOME. Profile defaults to sdk, and each Patches entry becomes an absolute --patch argument. ReasoningEffort becomes reasoningEffort in initialize, while MaxTokens == 0 omits maxTokens.

The initialize handshake has its own 30-second default timeout through InitializeTimeoutSeconds; RequestTimeoutSeconds controls ordinary requests.

Launch channels are resolved from most explicit to least explicit:

1. LaunchArgsOverride.
2. Command with Args.
3. DSHBin.
4. RuntimeBin or BridgeBin (deprecated compatibility aliases).
5. DSH_RUNTIME_BIN (deprecated compatibility override).
6. The bundled runtime downloader.

DSHBin and the bundled downloader append --profile <Profile> and ordered --patch <absolute path> arguments, and require an explicit Harness home. The new runtime has no downloaded default cordis.yml; its profile owns runtime configuration. LaunchArgsOverride remains an internal-style escape hatch for fake runtimes and bypasses the home check.

Sessions and results

session, err := harness.StartSession("session-reuse")
if err != nil {
	panic(err)
}

result, err := session.Run(
	deepseekharness.BlocksInput([]deepseekharness.JSONObject{
		{"type": "text", "text": "Inspect this task."},
	}),
	func(notification deepseekharness.Notification) {
		if notification.Method == "session.event" {
			// Render or persist the event as needed.
		}
	},
)

Run waits for the prompt's durable agent/inbox/spliced receipt, then collects notifications until the root session reaches its next idle state. Notifications from known descendant sessions are included through subagent.started lineage edges. RunResult.Events contains root-session events only. FinalResponse is the last committed root assistant text in the interval, and FinishReason is the last turn/end reason kind when present. Those values describe the owned activity interval, not an output causally assigned to only the submitted prompt.

The callback is invoked for each collected notification after the inbox receipt. FinishReason is a *string; it is nil when no turn ended.

Low-level client

HarnessClient exposes the protocol surface used by advanced integrations:

client := deepseekharness.NewHarnessClient(deepseekharness.HarnessClientOptions{
	DSHBin:  "/path/to/dsh",
	DSHHome: "/absolute/path/to/dsh-home",
	Profile: "sdk",
})
defer client.Close()

if err := client.Start(); err != nil {
	panic(err)
}
_, err := client.Initialize(deepseekharness.InitializeParams{
	CWD: "./workspace", Provider: "deepseek-official", Model: "deepseek-v4-flash",
	ReasoningEffort: "max",
})

The client supports Request, Notify, SessionPrompt, Subscribe, SubscribeSessionTree, NextNotification, NextRequest, Respond, and RespondError. Server-to-client requests are queued until the caller answers them. Notifications that no subscription matched are available through NextNotification.

Errors

Errors are concrete types suitable for errors.As: JsonRpcError, RequestTimeoutError, ProtocolError, TransportClosedError, RuntimeResolveError, and IOError. TransportClosedError includes the process exit code when available and the last 400 stderr lines.

Development

gofmt -w *.go
go vet ./...
go test -race ./...

GitHub Actions runs formatting, vet, race-enabled tests, and the regular test suite on Linux and macOS. Releases are created from matching v* tags; see docs/ROADMAP.md for planned parity work. For the next upstream tag update, follow the tag update runbook.

Code Contribution Guide

The full contributor workflow, including branch, commit, and pull request guidance, is in docs/CONTRIBUTING.md.

Relationship to DeepSeek Harness

This repository owns the Go SDK. The runtime is published by the DeepSeek Harness project as deepseek-harness-runtime-bin. The SDK follows the documented stdio JSON-RPC protocol and tracks the Python SDK's public behavior as that implementation evolves.