Building CLI backend plugins

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CLI backend plugins let OpenClaw call a local AI CLI as a text inference backend. The backend appears as a provider prefix in model refs:

acme-cli/acme-large

Use a CLI backend when the upstream integration is already exposed as a local command, when the CLI owns local login state, or when the CLI is a useful fallback if API providers are unavailable.

说明

If the upstream service exposes a normal HTTP model API, write a provider plugin instead. If the upstream runtime owns complete agent sessions, tool events, compaction, or background task state, use an agent harness.

What the plugin owns

A CLI backend plugin has three contracts:

Contract	File	Purpose
Package entry	package.json	Points OpenClaw at the plugin runtime module
Manifest ownership	openclaw.plugin.json	Declares the backend id before runtime loads
Runtime registration	index.ts	Calls api.registerCliBackend(...) with command defaults

The manifest is discovery metadata. It does not execute the CLI and does not register runtime behavior. Runtime behavior starts when the plugin entry calls api.registerCliBackend(...).

Minimal backend plugin

步骤 1：Create package metadata

```json package.json
{
  "name": "@acme/openclaw-acme-cli",
  "version": "1.0.0",
  "type": "module",
  "openclaw": {
    "extensions": ["./index.ts"],
    "compat": {
      "pluginApi": ">=2026.3.24-beta.2",
      "minGatewayVersion": "2026.3.24-beta.2"
    },
    "build": {
      "openclawVersion": "2026.3.24-beta.2",
      "pluginSdkVersion": "2026.3.24-beta.2"
    }
  },
  "dependencies": {
    "openclaw": "^2026.3.24"
  },
  "devDependencies": {
    "typescript": "^5.9.0"
  }
}
```

Published packages must ship built JavaScript runtime files. If your source
entry is `./src/index.ts`, add `openclaw.runtimeExtensions` that points at
the built JavaScript peer. See [Entry points](/tutorials/plugins/sdk-entrypoints).

步骤 2：Declare backend ownership

```json openclaw.plugin.json
{
  "id": "acme-cli",
  "name": "Acme CLI",
  "description": "Run Acme's local AI CLI through OpenClaw",
  "cliBackends": ["acme-cli"],
  "setup": {
    "cliBackends": ["acme-cli"],
    "requiresRuntime": false
  },
  "activation": {
    "onStartup": false
  },
  "configSchema": {
    "type": "object",
    "additionalProperties": false
  }
}
```

`cliBackends` is the runtime ownership list. It lets OpenClaw auto-load the
plugin when config or model selection mentions `acme-cli/...`.

`setup.cliBackends` is the descriptor-first setup surface. Add it when
model discovery, onboarding, or status should recognize the backend without
loading plugin runtime. Use `requiresRuntime: false` only when those static
descriptors are enough for setup.

步骤 3：Register the backend

```typescript index.ts
import { definePluginEntry } from "openclaw/plugin-sdk/plugin-entry";
import {
  CLI_FRESH_WATCHDOG_DEFAULTS,
  CLI_RESUME_WATCHDOG_DEFAULTS,
  type CliBackendPlugin,
} from "openclaw/plugin-sdk/cli-backend";

function buildAcmeCliBackend(): CliBackendPlugin {
  return {
    id: "acme-cli",
    liveTest: {
      defaultModelRef: "acme-cli/acme-large",
      defaultImageProbe: false,
      defaultMcpProbe: false,
      docker: {
        npmPackage: "@acme/acme-cli",
        binaryName: "acme",
      },
    },
    config: {
      command: "acme",
      args: ["chat", "--json"],
      output: "json",
      input: "stdin",
      modelArg: "--model",
      sessionArg: "--session",
      sessionMode: "existing",
      sessionIdFields: ["session_id", "conversation_id"],
      systemPromptFileArg: "--system-file",
      systemPromptWhen: "first",
      imageArg: "--image",
      imageMode: "repeat",
      reliability: {
        watchdog: {
          fresh: { ...CLI_FRESH_WATCHDOG_DEFAULTS },
          resume: { ...CLI_RESUME_WATCHDOG_DEFAULTS },
        },
      },
      serialize: true,
    },
  };
}

export default definePluginEntry({
  id: "acme-cli",
  name: "Acme CLI",
  description: "Run Acme's local AI CLI through OpenClaw",
  register(api) {
    api.registerCliBackend(buildAcmeCliBackend());
  },
});
```

The backend id must match the manifest `cliBackends` entry. The registered
`config` is only the default; user config under
`agents.defaults.cliBackends.acme-cli` is merged over it at runtime.

Config shape

CliBackendConfig describes how OpenClaw should launch and parse the CLI:

Field	Use
command	Binary name or absolute command path
args	Base argv for fresh runs
resumeArgs	Alternate argv for resumed sessions; supports {sessionId}
output / resumeOutput	Parser: json, jsonl, or text
input	Prompt transport: arg or stdin
modelArg	Flag used before the model id
modelAliases	Map OpenClaw model ids to CLI-native ids
sessionArg / sessionArgs	How to pass a session id
sessionMode	always, existing, or none
sessionIdFields	JSON fields OpenClaw reads from CLI output
systemPromptArg / systemPromptFileArg	System prompt transport
systemPromptWhen	first, always, or never
imageArg / imageMode	Image path support
serialize	Keep same-backend runs ordered
reliability.watchdog	No-output timeout tuning

Prefer the smallest static config that matches the CLI. Add plugin callbacks only for behavior that really belongs to the backend.

Advanced backend hooks

CliBackendPlugin can also define:

Hook	Use
normalizeConfig(config, context)	Rewrite legacy user config after merge
resolveExecutionArgs(ctx)	Add request-scoped flags such as thinking effort
prepareExecution(ctx)	Create temporary auth or config bridges before launch
transformSystemPrompt(ctx)	Apply a final CLI-specific system prompt transform
textTransforms	Bidirectional prompt/output replacements
defaultAuthProfileId	Prefer a specific OpenClaw auth profile
authEpochMode	Decide how auth changes invalidate stored CLI sessions
nativeToolMode	Declare whether the CLI has always-on native tools
bundleMcp / bundleMcpMode	Opt into OpenClaw's loopback MCP tool bridge

Keep these hooks provider-owned. Do not add CLI-specific branches to core when a backend hook can express the behavior.

MCP tool bridge

CLI backends do not receive OpenClaw tools by default. If the CLI can consume an MCP configuration, opt in explicitly:

return {
  id: "acme-cli",
  bundleMcp: true,
  bundleMcpMode: "codex-config-overrides",
  config: {
    command: "acme",
    args: ["chat", "--json"],
    output: "json",
  },
};

Supported bridge modes are:

Mode	Use
claude-config-file	CLIs that accept an MCP config file
codex-config-overrides	CLIs that accept config overrides on argv
gemini-system-settings	CLIs that read MCP settings from their system settings directory

Only enable the bridge when the CLI can actually consume it. If the CLI has its own built-in tool layer that cannot be disabled, set nativeToolMode: "always-on" so OpenClaw can fail closed when a caller requires no native tools.

User configuration

Users can override any backend default:

{
  agents: {
    defaults: {
      cliBackends: {
        "acme-cli": {
          command: "/opt/acme/bin/acme",
          args: ["chat", "--json", "--profile", "work"],
          modelAliases: {
            large: "acme-large-2026",
          },
        },
      },
      model: {
        primary: "openai/gpt-5.5",
        fallbacks: ["acme-cli/large"],
      },
    },
  },
}

Document the minimum override users are likely to need. Usually that is only command when the binary is outside PATH.

Verification

For bundled plugins, add a focused test around the builder and setup registration, then run the plugin's targeted test lane:

pnpm test extensions/acme-cli

For local or installed plugins, verify discovery and one real model run:

openclaw plugins inspect acme-cli --runtime --json
openclaw agent --message "reply exactly: backend ok" --model acme-cli/acme-large

If the backend supports images or MCP, add a live smoke that proves those paths with the real CLI. Do not rely on static inspection for prompt, image, MCP, or session-resume behavior.

Checklist

验证

package.json has openclaw.extensions and built runtime entries for published packages

验证

openclaw.plugin.json declares cliBackends and intentional activation.onStartup

验证

setup.cliBackends is present when setup/model discovery should see the backend cold

验证

api.registerCliBackend(...) uses the same backend id as the manifest

验证

User overrides under agents.defaults.cliBackends.<id> still win

验证

Session, system prompt, image, and output parser settings match the real CLI contract

验证

Targeted tests and at least one live CLI smoke prove the backend path

Related

• CLI backends - user configuration and runtime behavior
• Building plugins - package and manifest basics
• Plugin SDK overview - registration API reference
• Plugin manifest - cliBackends and setup descriptors
• Agent harness - full external agent runtimes