dart_acp_codex 0.1.4

A typed ACP client and adapter for local Codex processes.

dart_acp_codex

A strongly typed Dart ACP adapter for local Codex processes.

dart_acp_codex connects Agent Client Protocol clients to a Codex app-server. It can run as a stdio executable or be embedded as a typed AcpAgentApp in another Dart program.

Install

dart pub add dart_acp_codex

The default executable also needs codex on PATH, or an explicit CODEX_EXECUTABLE.

Run over stdio

dart run dart_acp_codex

Other executable modes are:

dart run dart_acp_codex --version
dart run dart_acp_codex login
dart run dart_acp_codex cli --help

With no arguments, stdin and stdout are reserved for ACP NDJSON. Diagnostics are written through the configured diagnostic callback or stderr, never the protocol stream.

Connect as a client

import 'package:dart_acp_codex/dart_acp_codex.dart';

Future<void> main() async {
  final client = await CodexAcpClient.start(
    options: CodexAcpClientOptions(
      executable: '/opt/codex',
      modelProvider: 'openai',
      onDiagnostic: (event) {
        // Forward event.message to your application logger.
      },
    ),
  );

  try {
    final session = await client.agent.createSession(
      NewSessionRequest(cwd: '/workspace', mcpServers: const []),
    );
    print(session.sessionId.value);
  } finally {
    await client.close();
  }
}

CodexAcpClient owns the local runtime, waits for both ACP and app-server initialization, and closes both sides idempotently. Applications that need their own ACP transport can instead create a CodexRuntime, call createAgent(), and connect the resulting agent.app.

Applications with an existing service boundary can implement CodexBackend and inject it into either API. The public backend contract uses immutable, validated CodexJsonObject values and typed notification/request variants.

Authentication

The agent supports:

• API-key login, using request metadata first and then CODEX_API_KEY or OPENAI_API_KEY.
• ChatGPT login when browser authentication is available. Set NO_BROWSER to omit this method.
• A custom OpenAI-compatible gateway supplied by ACP authentication metadata or the provider API.

Gateway headers are kept in process configuration and are never returned by provider discovery or included in diagnostics.

Configuration

CodexAcpClientOptions aliases CodexAdapterOptions; it controls the executable, base app-server configuration, model provider, environment, shutdown grace period, stderr bound, and diagnostic sink. The executable additionally recognizes:

Environment variable	Meaning
CODEX_EXECUTABLE	Executable path or command; defaults to codex
CODEX_ACP_MODEL_PROVIDER	Preferred Codex model-provider id
CODEX_ACP_SHUTDOWN_TIMEOUT_MS	Positive shutdown grace period in milliseconds
CODEX_ACP_MAX_STDERR_CHARS	Positive maximum retained stderr tail
CODEX_API_KEY / OPENAI_API_KEY	API-key fallback
NO_BROWSER	Disable browser-backed ChatGPT authentication

Sessions publish typed options for sandbox/approval mode, model, reasoning effort, and the fast service tier when the selected model supports it. Standard and plan collaboration modes are available through ACP session mode methods and /plan.

Embedded clients can select Codex's native automatic approval reviewer for standard workspace-write turns:

CodexAdapterOptions(
  workspaceWriteApprovalsReviewer: CodexApprovalsReviewer.autoReview,
);

Read-only and plan turns remain human-reviewed, and full-access turns retain their never approval policy.

Providers and extensions

The experimental ACP provider surface advertises one optional provider: custom-gateway. It accepts the openai protocol, returns only non-secret current routing data, rejects malformed configurations, and can be disabled idempotently.

Two typed underscore extensions are exported:

• _session/steering queues additional text or image input. It reports whether input joined the active turn, started a new turn, or failed.
• _session/goal_control creates or edits, pauses, resumes, or clears the current goal. Goal-control support is advertised through agentCapabilities._meta.goalControl, and sessions publish the current goal through the shared session_info_update._meta.goal snapshot.

No non-underscore compatibility extensions are registered.

Sessions, tools, and commands

The adapter supports session new/load/resume/list/close/delete, ordered streaming updates, cancellation, history replay, additional workspace roots, stdio and HTTP MCP servers, permission requests, form/URL elicitations, and user-input questions.

Mapped updates include agent messages, reasoning, plans, usage, titles, warnings, errors, commands, file changes, MCP/dynamic tools, web actions, images, collaboration activity, and context compaction. Unknown events are ignored without affecting other sessions.

Published commands include /status, /mcp, /skills, /review, /review-branch, /review-commit, /compact, /plan, /goal, and /logout.

Security and lifecycle

• Protocol values are defensively copied and validated at the boundary.
• Secret headers and API keys are excluded from display strings and diagnostics.
• Stderr retention, NDJSON frames, pending JSON-RPC work, and history recovery are bounded.
• Session notifications are serialized and fenced by generation so closed sessions cannot receive stale updates.
• Child shutdown is idempotent and escalates to termination after the configured grace period.

Example and benchmarks

The deterministic example demonstrates initialization, session configuration, a streamed turn, permission handling, and shutdown without credentials or a local executable:

dart run example/main.dart

The benchmark suite covers message and terminal deltas, mixed event mapping, history replay, steering serialization, and multi-session routing:

dart run benchmark/adapter_benchmark.dart
dart run benchmark/adapter_benchmark.dart --smoke

Contributing

See the repository contribution guide. Run formatting, analysis, tests, the example smoke test, and the benchmark smoke mode before opening a change.

License

Licensed under the Apache License 2.0.