---
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 as a fallback when 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 or 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` pointing 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 model selection or `agentRuntime.id` 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, type OpenClawPluginApi } from "openclaw/plugin-sdk/plugin-entry";

    function buildAcmeCliBackend(): Parameters<OpenClawPluginApi["registerCliBackend"]>[0] {
      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", "--output-format", "stream-json", "--prompt", "{prompt}"],
          resumeArgs: [
            "chat",
            "--resume",
            "{sessionId}",
            "--output-format",
            "stream-json",
            "--prompt",
            "{prompt}",
          ],
          output: "jsonl",
          resumeOutput: "jsonl",
          jsonlDialect: "gemini-stream-json",
          input: "arg",
          modelArg: "--model",
          modelAliases: {
            large: "acme-large-2026",
            fast: "acme-fast-2026",
          },
          sessionArgs: ["--session", "{sessionId}"],
          sessionMode: "existing",
          sessionIdFields: ["session_id", "conversation_id"],
          systemPromptFileArg: "--system-file",
          systemPromptWhen: "first",
          imageArg: "--image",
          imageMode: "repeat",
          imagePathScope: "workspace",
          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
    adapter is authoritative plugin code; OpenClaw config selects the backend
    but does not rewrite its command contract.

  </Step>
</Steps>

## Config shape

`CliBackendConfig` describes how OpenClaw should launch and parse the CLI. The
worked example above intentionally exercises the same command, resume, JSONL,
model-alias, session, and image fields as the bundled
`google-gemini-cli` adapter:

| 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`                                                |
| `jsonlDialect`                                            | JSONL event dialect: `claude-stream-json` or `gemini-stream-json`                 |
| `liveSession`                                             | Long-lived CLI process mode (`claude-stdio`)                                      |
| `input`                                                   | Prompt transport: `arg` or `stdin`                                                |
| `maxPromptArgChars`                                       | Max prompt length for `arg` mode before falling back to stdin                     |
| `env` / `clearEnv`                                        | Extra env vars to inject, or names to strip before launch                         |
| `modelArg`                                                | Flag used before the model id                                                     |
| `modelAliases`                                            | Map OpenClaw model ids to CLI-native ids                                          |
| `sessionArgs`                                             | How to pass a session id using `{sessionId}`                                      |
| `sessionMode`                                             | `always`, `existing`, or `none`                                                   |
| `sessionIdFields`                                         | JSON fields OpenClaw reads from CLI output                                        |
| `systemPromptArg` / `systemPromptFileArg`                 | System prompt transport                                                           |
| `systemPromptFileConfigArg` / `systemPromptFileConfigKey` | Config-override transport for a system prompt file (for example `-c`)             |
| `systemPromptMode`                                        | `append` or `replace`                                                             |
| `systemPromptWhen`                                        | `first`, `always`, or `never`                                                     |
| `imageArg` / `imageMode`                                  | Image path flag and how to pass multiple images (`repeat` or `list`)              |
| `imagePathScope`                                          | Where staged image files live before handoff: `temp` or `workspace`               |
| `serialize`                                               | Keep same-backend runs ordered                                                    |
| `reseedFromRawTranscriptWhenUncompacted`                  | Opt in to bounded raw-transcript reseed before compaction for safe session resets |
| `freshSessionRecovery`                                    | Fresh recovery policy after a recoverable resumed-session failure                 |
| `reliability.watchdog`                                    | No-output timeout tuning, separate for fresh vs resumed runs                      |

Omit `reliability.watchdog` to inherit the standard profiles, including the
longer resumed-run budget for cron and explicit timeouts. Set it only when a
backend intentionally needs its own watchdog policy.

`freshSessionRecovery` is a backend-owned compatibility contract:

- Leave it undefined or set it to `"replace-binding"` to preserve the legacy
  clear-and-reseed behavior. OpenClaw clears the persisted binding and retries
  with a fresh session when the failure is eligible for recovery.
- Set it to `"invalidated-only"` to suppress fresh replacement unless the
  canonical invalidation predicate proves the old session is dead. Currently,
  only `session_expired` does so.

Choose the value from the CLI or SDK session contract, not from a provider id
or broad error class. The bundled Anthropic backend uses `"invalidated-only"`;
its Agent SDK contract does not treat non-expiration failures as proof that the
conversation can no longer resume.

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)` | Normalize the registered static adapter with runtime context                |
| `resolveExecutionArgs(ctx)`        | Add request-scoped flags such as thinking effort or side-question isolation |
| `prepareExecution(ctx)`            | Create temporary auth, config, or environment 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 native tools are absent, always on, or host-selectable      |
| `toolAvailabilityEnforcement`      | Declare whether exact tool caps are enforced in argv or execution staging   |
| `sideQuestionToolMode`             | Declare disabled native tools for `/btw` side questions                     |
| `bundleMcp` / `bundleMcpMode`      | Opt into OpenClaw's loopback MCP tool bridge                                |
| `ownsNativeCompaction`             | Backend owns its own automatic compaction - OpenClaw defers                 |
| `manualCompaction`                 | Atomic command, transport, and positive-acknowledgement contract            |
| `subscriptionAuthDispatch`         | Opted-in embedded runs on subscription credentials execute via this backend |
| `runtimeArtifact`                  | Bound a script launcher to its complete bundled package tree                |

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

`prepareExecution(ctx)` receives `ctx.contextTokenBudget`, the effective token
limit selected for the run. Backends that own native compaction can map that
budget into their CLI-specific launch contract. It also receives the optional
effective `ctx.thinkingLevel`: `off`, `minimal`, `low`, `medium`, `high`,
`xhigh`, `adaptive`, or `max`. Use that field when the selected level must be
applied through launch environment or staged configuration; the same field is
available to `resolveExecutionArgs(ctx)` for native CLI flags.

`prepareExecution(ctx)` may also return an optional `execute` transport when a
backend owns a vendor-supported SDK for the installed CLI. The transport
receives the exact prepared command, arguments, environment, prompt, session,
and tool availability; it yields the backend's existing structured stream
records. Optional `promptContext.prependContext` and `promptContext.appendContext`
are private prompt-build additions, separate from the ordinary `prompt`. Transport
them through the native SDK's private context mechanism; never record them as
operator-authored input. OpenClaw's policy and observation hooks still receive the
complete logical prompt. Native tool actions must use the provided, run-bound
`requestToolPermission` callback rather than creating independent approval
authority. OpenClaw retains cancellation, watchdogs, session policy, and MCP
grant ownership. Explicit credential forwarding, paired-node execution, and
manual compaction continue through the existing host-managed process path.

`runtimeArtifact` is plugin-owned. It is consulted
only when a live inference turn mints or revalidates verified setup authority;
normal CLI runs do not require it. A backend without this declaration cannot
mint verified CLI setup authority. A `bundled-package-tree` declaration names
the exact `package.json` owner and requires the package entrypoint to be the
command. OpenClaw hashes the bounded complete installed package tree, including
nested dependencies, and fails closed for redirecting symlinks,
launchers outside the declared package, required external dependency
declarations, oversized trees, and unknown scripts. Declare this only when that
tree contains the complete inference implementation; optional tool integrations
do not make an external implementation graph safe.

If the same backend also ships a self-contained native executable, list its
canonical basenames in `nativeExecutableNames`. Other native commands remain
unverified.

`ctx.executionMode` is `"agent"` for normal turns and `"side-question"` for
ephemeral `/btw` calls. Use it when the CLI needs different one-shot flags,
such as disabling native tools, session persistence, or resume behavior for
BTW. If a backend normally has `nativeToolMode: "always-on"` but its
side-question argv reliably disables those tools, also set
`sideQuestionToolMode: "disabled"`; otherwise OpenClaw fails closed when BTW
requires a no-tools CLI run.

Set `nativeToolMode: "selectable"` only when the backend can disable every
backend-native tool for an individual run. Restricted runs receive a canonical
contract: `ctx.toolAvailability.native` is the exact backend-native list and
`ctx.toolAvailability.openClaw` is the exact list of OpenClaw tool names. The
host independently limits the generated MCP configuration and grant to that
OpenClaw list; plugins must not translate it in core or add transport prefixes.

Declare how the backend enforces that contract:

- `toolAvailabilityEnforcement: "execution-args"` requires
  `resolveExecutionArgs`. The hook must replace conflicting tool flags, disable
  customization surfaces that can execute outside the selected tools, and
  return enforcing argv for both fresh and resumed runs.
- `toolAvailabilityEnforcement: "prepare-execution"` requires
  `prepareExecution`. The hook must stage an exact per-run policy and return
  `toolAvailabilityEnforced: true`; missing acknowledgement fails closed and
  OpenClaw cleans up the staged resources before launch.

Runtime caps such as cron `toolsAllow` are normalized and group-expanded by
OpenClaw before this contract is built. Native tools are disabled, and a
backend without a complete declared enforcement path fails before execution.

### `parseJsonlEvent`: provider-specific JSONL streams

Set `parseJsonlEvent` when a backend emits line-delimited JSON that does not
match the built-in Claude, Codex, or Gemini dialects. The hook receives one raw
line plus the resolved backend id and config, and returns one normalized event,
multiple events, or `null` to let the built-in parser try the line.

Supported events are incremental assistant text, incremental thinking, native
tool start/result display, session ids, and terminal results. Terminal results
may include final text, usage, an error, and a successor session id. Session ids
reported by either event shape participate in resumed-session and fork
persistence.

Tool events describe work the backend already performed. OpenClaw renders and
summarizes them, but does not treat them as host tool execution, trusted
diagnostics, loopback correlation, or message-delivery evidence.

### `ownsNativeCompaction`: opting out of OpenClaw compaction

If your backend runs an agent that compacts its **own** transcript, set
`ownsNativeCompaction: true` so OpenClaw's safeguard summarizer never runs
against its sessions - automatic CLI compaction defers to the backend and the
turn proceeds. `claude-cli` declares it because Claude Code compacts
internally with no harness endpoint. It also declares
`manualCompaction`, so an explicit OpenClaw `/compact` resumes the
bound Claude Code session and invokes its native `/compact` command without
recording a conversation turn. Native-harness sessions such as Codex keep
routing to their harness compaction endpoint instead.

**Only declare it when all of the following hold**, or a deferred
over-budget session can stay over budget or go stale (OpenClaw no longer
rescues it):

- the backend reliably compacts or bounds its own transcript as it nears its
  window;
- it persists a resumable session so the compacted state survives turns
  (for example `--resume` / `--session-id`);
- it is not a native-harness compaction session - matching `agentHarnessId`
  sessions route to the harness endpoint instead.

If the backend supports an in-place manual command, declare it alongside the
ownership flag:

```typescript
manualCompaction: {
  buildPrompt: (instructions) =>
    instructions ? `/compact ${instructions}` : "/compact",
  input: "arg",
  validateOutput: (rawOutput) =>
    rawOutput.includes('"type":"compaction_complete"')
      ? { ok: true }
      : { ok: false, reason: "CLI did not confirm compaction." },
},
```

The builder receives optional `/compact` instructions. The validator receives
the bounded raw process output and must require a backend-owned positive
acknowledgement; a zero exit alone is not proof of compaction. Do not declare
this capability for a command that creates a separate session or requires an
ordinary model turn.

## 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:

| 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. If it can disable every native tool per run, use `"selectable"` with the
`resolveExecutionArgs` contract above.

## Selecting the backend

Users select a standalone backend through its model-ref prefix. A backend that
declares a canonical `modelProvider` can instead be selected through that
provider model's `agentRuntime.id`. Adapter mechanics remain in the plugin:

```json5
{
  agents: {
    defaults: {
      model: {
        primary: "openai/gpt-5.6-sol",
        fallbacks: ["acme-cli/large"],
      },
    },
  },
}
```

Put credentials in OpenClaw auth profiles or plugin-owned config. Ensure the
registered command is on the gateway service's `PATH`; deployments that need a
different path or argv should change or wrap the plugin registration.

## 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>The backend model prefix or model-scoped `agentRuntime.id` selects the registration</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) - runtime selection and 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
