Harnesses
Partly builtSome of this works today; the page says which parts.
A harness is the agent CLI that does the work inside your sandbox. HareBox runs it non-interactively as the sandbox's user account, streams what it does as events, keeps its session with the conversation, and stops it when a budget runs out.
harebox harnesses
| ID | Harness | How HareBox drives it | In the base image |
|---|---|---|---|
claude |
Claude Code | claude -p with its stream-json output |
Yes |
codex |
OpenAI Codex | codex exec --json |
Yes |
opencode |
OpenCode | opencode run --format json |
Yes |
shell |
Runs the prompt as a command | Directly; needs no model | Always |
pi |
pi | Simulated adapter | Yes |
openclaw |
OpenClaw | Simulated adapter | Yes |
kimi |
Kimi Code | Simulated adapter | On first use |
mistral |
Mistral Vibe | Simulated adapter | On first use |
hermes |
Hermes | Simulated adapter | On first use |
prime |
Prime Agent | Simulated adapter | On first use |
cursor |
Cursor CLI | Simulated adapter | On first use |
Status: on real machines, claude, codex and opencode run the real CLI in the sandbox, and their adapters are tested against each CLI's event format. A turn needs a model key, connected as described in Credentials proxy. The other harnesses keep their simulated adapters, which stream a scripted turn and report simulated: true, until each has a tested adapter. On the labelled simulator, every harness except shell is simulated. Simulated adapters don't call any model.
- HareBox checks that the CLI exists in the sandbox. If it doesn't, the turn fails with an install hint.
- It runs the CLI as
user, in/home/user, with the sandbox's environment. Model keys arrive only as credential-proxy placeholders, so the real key never enters the machine. - Text, tool calls and token usage stream as
prompt.*events. - The CLI's session ID is saved with the conversation, so the next prompt in it resumes the same session, after a stop or in a fork.
| Field | CLI flag | Used by |
|---|---|---|
model |
--model |
All. Leave it out, or send default, for the harness's own default |
reasoning_effort |
--effort |
Codex (low, medium, high) |
attachments |
All: files are put in ~/.harebox/attachments/<prompt>/ and named in the prompt |
|
budget_usd |
--budget |
All. The turn stops when its spend reaches this |
Install any CLI with harebox-harness install NAME (needs the sandbox's network), or run your own agent with harebox exec. See Customize.