Files
openclaw/docs/plugins/cli-backend-plugins.md
Peter Steinberger 42ecd5d95e fix(acpx): harden session lifecycle cleanup
Harden ACPX process cleanup with lease-backed ownership verification, startup orphan reaping, reusable cancel semantics, and spawned-session visibility fixes.
2026-05-07 07:30:37 +01:00

311 lines
12 KiB
Markdown

---
summary: "Build a plugin that registers a local AI CLI backend"
title: "Building CLI backend plugins"
sidebarTitle: "CLI backend plugins"
read_when:
- You are building a local AI CLI backend plugin
- You want to register a backend for model refs such as acme-cli/model
- You need to map a third-party CLI into OpenClaw's text fallback runner
---
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:
```text
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.
<Info>
If the upstream service exposes a normal HTTP model API, write a
[provider plugin](/plugins/sdk-provider-plugins) instead. If the upstream
runtime owns complete agent sessions, tool events, compaction, or background
task state, use an [agent harness](/plugins/sdk-agent-harness).
</Info>
## 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
<Steps>
<Step title="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](/plugins/sdk-entrypoints).
</Step>
<Step title="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.
</Step>
<Step title="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.
</Step>
</Steps>
## 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:
```typescript
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:
```json5
{
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:
```bash
pnpm test extensions/acme-cli
```
For local or installed plugins, verify discovery and one real model run:
```bash
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
<Check>`package.json` has `openclaw.extensions` and built runtime entries for published packages</Check>
<Check>`openclaw.plugin.json` declares `cliBackends` and intentional `activation.onStartup`</Check>
<Check>`setup.cliBackends` is present when setup/model discovery should see the backend cold</Check>
<Check>`api.registerCliBackend(...)` uses the same backend id as the manifest</Check>
<Check>User overrides under `agents.defaults.cliBackends.<id>` still win</Check>
<Check>Session, system prompt, image, and output parser settings match the real CLI contract</Check>
<Check>Targeted tests and at least one live CLI smoke prove the backend path</Check>
## Related
- [CLI backends](/gateway/cli-backends) - user configuration and runtime behavior
- [Building plugins](/plugins/building-plugins) - package and manifest basics
- [Plugin SDK overview](/plugins/sdk-overview) - registration API reference
- [Plugin manifest](/plugins/manifest) - `cliBackends` and setup descriptors
- [Agent harness](/plugins/sdk-agent-harness) - full external agent runtimes