Sandbox

Sandboxing is runtime-owned infrastructure. Tools can ask for shell or file operations, but the host decides what execution environment they receive.

Core Sandbox

import {
  NoopSandbox,
  type HarnessSandbox,
  type HarnessSandboxSession,
} from "@harness-kernel/core/runner/sandbox";

NoopSandbox returns failed command results and is safe for core-only tests where execution should not happen.

Local Sandbox

@harness-kernel/sandbox-local provides local shell execution:

import { LocalSandbox } from "@harness-kernel/sandbox-local";

const store = await createHarnessSessionStore({
  agent: { definition: agent },
  providers: [new OpenAIProvider()],
  defaultModel: "openai/gpt-5.1",
  sandbox: new LocalSandbox({
    workDir: ".",
    env: "minimal",
    defaultTimeoutMs: 30_000,
  }),
});

LocalSandbox resolves paths inside the configured work directory and executes commands with bash -lc.

Relationship To Node Tools

@harness-kernel/tools-node exposes mode-owned tools such as BashTool, ReadFileTool, WriteFileTool, EditFileTool, GlobTool, and GrepTool. Those tools call session.sandbox.exec().

The tools belong to modes. The sandbox belongs to the runtime host.