Codex SDK for Elixir

An idiomatic Elixir SDK for embedding OpenAI's Codex agent in your workflows and applications. This SDK wraps the codex-rs executable, providing a complete, production-ready interface with streaming support and comprehensive event handling.

Features

End-to-End Codex Lifecycle: Spawn, resume, and manage full Codex threads with rich turn instrumentation.
Multi-Transport Support: Default exec JSONL (codex exec --json) plus stateful app-server JSON-RPC over stdio (codex app-server) with multi-modal UserInput blocks.
CLI Passthrough and PTY Sessions: Codex.CLI can launch root codex, cloud, completion, features, mcp, sandbox, resume, fork, app-server, and other command-surface workflows directly.
Native OAuth: Codex.OAuth provides SDK-managed browser/device login, refresh, status, and logout with upstream-compatible auth.json persistence or memory-only sessions.
Upstream Compatibility: Mirrors Codex CLI flags (profile/OSS/full-auto/color/search/config overrides/review/resume) and handles app-server protocol drift (e.g. MCP list method rename fallbacks).
Streaming & Structured Output: Real-time events, per-thread output schemas, reasoning summary/content preservation, and typed app-server deltas.
File & Attachment Pipeline: Secure temp file registry and change events.
Approval Hooks & Sandbox Policies: Dynamic or static approval flows with registry-backed persistence.
Collaboration & Personality Controls: Collaboration modes, personality overrides, and web search mode toggles.
Tooling & MCP Integration: Built-in registry for Codex tool manifests, MCP client helpers, and elicitation handling.
Observability-Ready: Telemetry spans, OTLP exporters gated by environment flags, usage stats, and rate limit snapshots.
Realtime API Support: Full integration with OpenAI Realtime API for bidirectional voice interactions with WebSocket streaming.
Voice Pipeline: Non-realtime STT -> Workflow -> TTS pipeline with streaming audio support and multi-turn conversations.

Installation

Add codex_sdk to your list of dependencies in mix.exs:

def deps do
  [
    {:codex_sdk, "~> 0.14.0"}
  ]
end

Prerequisites

You must have the codex CLI installed. Install it via npm or Homebrew:

# Using npm
npm install -g @openai/codex

# Using Homebrew
brew install codex

The SDK does not vendor codex-rs; it shells out to the codex executable on your system. Path resolution follows this order:

codex_path_override supplied in Codex.Options.new/1
CODEX_PATH environment variable
System.find_executable("codex")

Make sure the binary at the resolved location is executable and kept up to date.

For authentication, sign in with your ChatGPT account (this stores credentials for the CLI):

codex
# Select "Sign in with ChatGPT"

Alternatively, set CODEX_API_KEY before starting your BEAM node. For normal CLI-backed SDK execution, auth resolution is:

CODEX_API_KEY
auth.json OPENAI_API_KEY
ChatGPT OAuth tokens stored under CODEX_HOME (default ~/.codex/auth.json, with legacy credential file support)

The SDK now also exposes native OAuth login via Codex.OAuth:

{:ok, result} =
  Codex.OAuth.login(
    storage: :file,
    interactive?: true
  )

Persistent Codex.OAuth login writes upstream-compatible auth.json and respects upstream auth_mode. Memory-only OAuth is also available for host-managed and app-server external auth flows. openai_base_url does not change the OAuth issuer; use auth_issuer only when you need to override the login authority itself.

Environment-aware OAuth behavior matches current native-app guidance:

local desktop prefers browser auth with PKCE + loopback callback
WSL starts with the browser path, then falls back to device code when the callback is unreachable
SSH/headless/container environments prefer device code
CI and other non-interactive environments never auto-start login; existing credentials are used or the call fails clearly

If cli_auth_credentials_store = "keyring" is set in config and keyring support is unavailable, the SDK logs a warning and skips file-based tokens (remote model fetch falls back to bundled models). When cli_auth_credentials_store = "auto" and keyring is unavailable, the SDK falls back to file-based auth.

When an API key is supplied, the SDK forwards it as both CODEX_API_KEY and OPENAI_API_KEY to the codex subprocess to align with provider expectations.

Base URL precedence is: explicit :base_url in Codex.Options.new/1, then layered openai_base_url from config.toml, then OPENAI_BASE_URL, then the OpenAI default (https://api.openai.com/v1). User-defined [model_providers] entries extend the built-in provider set, but reserved built-ins such as openai, ollama, and lmstudio cannot be redefined.

Custom trust roots use CODEX_CA_CERTIFICATE first and SSL_CERT_FILE second. Blank values are ignored. The same PEM bundle is applied consistently to Codex CLI subprocesses, direct HTTP clients, remote model fetches, MCP HTTP/OAuth, realtime websockets, and voice HTTP requests.

Default model: Codex.Models.default_model/0 currently resolves to gpt-5.4 with the bundled catalog unless CODEX_MODEL, OPENAI_DEFAULT_MODEL, CODEX_MODEL_DEFAULT, or a fresher ChatGPT /models cache overrides it.

The SDK always loads the bundled upstream model catalog from priv/models.json, which is synced from the vendored upstream catalog in codex/codex-rs/core/models.json. When ChatGPT auth tokens are available it can still refresh /models and cache the result, but the old features.remote_models flag is no longer required for current catalog/default behavior. See guides/07-models-and-reasoning.md for the current bundled snapshot and how to inspect the effective runtime list.

See the OpenAI Codex documentation for more authentication options.

Quick Start

Basic Usage

# Start a new conversation
{:ok, thread} = Codex.start_thread()

# Run a turn and get results
{:ok, result} = Codex.Thread.run(thread, "Explain the purpose of GenServers in Elixir")

# Access the final response
IO.puts(result.final_response)

# Inspect all items (messages, reasoning, commands, file changes, etc.)
IO.inspect(result.items)

# Continue the conversation
{:ok, next_result} = Codex.Thread.run(thread, "Give me an example")

App-server Transport (Optional)

The SDK defaults to exec JSONL for backwards compatibility. To use the stateful app-server transport:

{:ok, codex_opts} = Codex.Options.new(%{api_key: System.fetch_env!("CODEX_API_KEY")})
{:ok, conn} = Codex.AppServer.connect(codex_opts)

{:ok, thread} =
  Codex.start_thread(codex_opts, %{
    transport: {:app_server, conn},
    working_directory: "/project"
  })

{:ok, result} = Codex.Thread.run(thread, "List the available skills for this repo")

{:ok, %{"data" => skills}} = Codex.AppServer.skills_list(conn, cwds: ["/project"])

When you need experimental app-server fields such as approvals_reviewer or granular approval policies, create the connection with Codex.AppServer.connect(codex_opts, experimental_api: true).

When the managed codex app-server child should run against an isolated repo or temporary Codex home, pass launch overrides to connect/2 itself:

tmp_home = Path.join(System.tmp_dir!(), "codex-sdk-app-server-home")

{:ok, conn} =
  Codex.AppServer.connect(codex_opts,
    cwd: "/project",
    process_env: %{
      "CODEX_HOME" => tmp_home,
      "HOME" => Path.dirname(tmp_home),
      "USERPROFILE" => Path.dirname(tmp_home)
    }
  )

cwd and process_env apply to the app-server child process. Per-thread working directories still belong on working_directory / cwd thread params.

connect/2 also supports OAuth-aware child auth bootstrapping:

{:ok, conn} =
  Codex.AppServer.connect(codex_opts,
    experimental_api: true,
    process_env: %{"CODEX_HOME" => tmp_home},
    oauth: [
      mode: :auto,
      storage: :memory,
      auto_refresh: true
    ]
  )

For oauth: [storage: :file | :auto], the SDK resolves auth against the effective child CODEX_HOME before launching the child. For oauth: [storage: :memory], it starts the child, logs in with external chatgptAuthTokens, and attaches a connection-owned refresh responder. Set auto_refresh: false when you want to handle account/chatgptAuthTokens/refresh requests yourself.

Multi-modal input is supported on app-server transport:

input = [
  %{type: :text, text: "Explain this screenshot"},
  %{type: :local_image, path: "/tmp/screenshot.png"}
]

{:ok, result} = Codex.Thread.run(thread, input)

Note: exec JSONL transport still accepts text input only; list inputs return {:error, {:unsupported_input, :exec}}.

App-server-only APIs include:

Codex.AppServer.thread_list/2, thread_archive/2, thread_read/3, thread_fork/3, thread_rollback/3, thread_loaded_list/2
Codex.AppServer.model_list/2, config_read/2, config_write/4, config_batch_write/3, config_requirements/1
Codex.AppServer.fs_read_file/2, fs_write_file/3, fs_create_directory/3, fs_get_metadata/2, fs_read_directory/2, fs_remove/3, fs_copy/4
Codex.AppServer.plugin_list/2, plugin_read/3, plugin_install/3, plugin_uninstall/2
Codex.AppServer.skills_config_write/3, collaboration_mode_list/1, apps_list/2
Codex.AppServer.turn_interrupt/3
Codex.AppServer.fuzzy_file_search/3 (legacy v1 helper used by @ file search)
Codex.AppServer.command_write_stdin/4 (interactive command stdin)
Codex.AppServer.Account.* and Codex.AppServer.Mcp.* endpoints (including MCP reload)
Approvals via Codex.AppServer.subscribe/2 + Codex.AppServer.respond/3

Runnable app-server demos now include examples/live_app_server_filesystem.exs for fs/* and examples/live_app_server_plugins.exs for plugin/list + plugin/read using a disposable repo-local marketplace fixture plus an isolated temporary CODEX_HOME, rather than your real plugin config. examples/live_app_server_approvals.exs uses the same child-process isolation pattern to enable the under-development approval features only inside a temporary CODEX_HOME, so it can exercise live command/file/permissions approval flows without mutating your real Codex settings or writing inside this repository.

App-server v2 input blocks support text, image, localImage, skill, and mention. Legacy app-server v1 conversation flows are available via Codex.AppServer.V1.

Raw CLI Passthrough and Interactive Sessions

Use Codex.CLI.run/2 when you want literal command-surface parity with the upstream terminal client, and Codex.CLI.interactive/2 or Codex.CLI.start/2 when you need a long-running or PTY-backed session.

{:ok, codex_opts} = Codex.Options.new(%{})

# Safe one-shot command wrappers
{:ok, completion} = Codex.CLI.completion("zsh", codex_opts: codex_opts)
IO.puts(completion.stdout)

{:ok, features} = Codex.CLI.features_list(codex_opts: codex_opts)
IO.puts(features.stdout)

# Arbitrary raw command surface
{:ok, result} =
  Codex.CLI.run(
    ["cloud", "list", "--json"],
    codex_opts: codex_opts
  )

IO.puts(result.stdout)

# Prompt-mode root codex session over a PTY
{:ok, session} =
  Codex.CLI.interactive(
    "Summarize this repository in three bullets.",
    codex_opts: codex_opts
  )

:ok = Codex.CLI.Session.close_input(session)
{:ok, session_result} = Codex.CLI.Session.collect(session)
IO.puts(session_result.stdout)

This layer is also the simplest way to reach CLI-only workflows such as codex completion, codex cloud, codex execpolicy, codex features, codex mcp-server, and the root interactive client without dropping down to System.cmd/3 yourself.

Streaming Responses

For real-time processing of events as they occur:

{:ok, thread} = Codex.start_thread()

{:ok, stream} = Codex.Thread.run_streamed(
  thread,
  "Analyze this codebase and suggest improvements"
)

# Process events as they arrive
for event <- stream do
  case event do
    %Codex.Events.ItemStarted{item: item} ->
      IO.puts("New item: #{item.type}")

    %Codex.Events.ItemCompleted{item: %{type: "agent_message", text: text}} ->
      IO.puts("Response: #{text}")

    %Codex.Events.TurnCompleted{usage: usage} ->
      IO.puts("Tokens used: #{usage.input_tokens + usage.output_tokens}")

    _ ->
      :ok
  end
end

Structured Output

Request JSON responses conforming to a specific schema:

schema = %{
  "type" => "object",
  "properties" => %{
    "summary" => %{"type" => "string"},
    "issues" => %{
      "type" => "array",
      "items" => %{
        "type" => "object",
        "properties" => %{
          "severity" => %{"type" => "string", "enum" => ["low", "medium", "high"]},
          "description" => %{"type" => "string"},
          "file" => %{"type" => "string"}
        },
        "required" => ["severity", "description"]
      }
    }
  },
  "required" => ["summary", "issues"]
}

{:ok, thread} = Codex.start_thread()

{:ok, result} = Codex.Thread.run(
  thread,
  "Analyze the code quality of this project",
  output_schema: schema
)

# Parse the JSON response
{:ok, data} = Jason.decode(result.final_response)
IO.inspect(data["issues"])

Runnable Examples

The repository ships with standalone scripts under examples/ that you can execute via mix run. Live scripts (prefixed live_) hit the real Codex CLI using your existing CLI login—no extra API key wiring needed. To run everything sequentially:

./examples/run_all.sh

Examples that start Codex turns prefer reasoning_effort: :low; the SDK will coerce that to a higher supported level when the selected model requires it.

Or run individual scripts:

# Basic blocking turn and item traversal
mix run examples/basic_usage.exs

# Streaming patterns (real-time, progressive, stateful)
mix run examples/streaming.exs progressive

# Live model defaults + compaction/usage handling (CLI login or CODEX_API_KEY)
mix run examples/live_usage_and_compaction.exs "summarize recent changes"

# Live exec controls (env injection, cancellation token, timeout)
mix run examples/live_exec_controls.exs "list files and print CODEX_DEMO_ENV"

# Structured output decoding and struct mapping
mix run examples/structured_output.exs struct

# Conversation/resume workflow helpers
mix run examples/conversation_and_resume.exs save-resume

# Concurrency + collaboration demos
mix run examples/concurrency_and_collaboration.exs parallel lib/codex/thread.ex lib/codex/exec.ex

# Auto-run tool bridging (forwards outputs/failures to codex exec)
mix run examples/tool_bridging_auto_run.exs

# Live two-turn session using CLI login or CODEX_API_KEY
mix run examples/live_session_walkthrough.exs "your prompt here"

# Live tooling stream: shows shell + MCP events and falls back to last agent message
mix run examples/live_tooling_stream.exs "optional prompt"

# Live telemetry stream: prints thread/turn ids, source metadata, usage deltas, diffs, and compaction (low reasoning, fast prompt)
mix run examples/live_telemetry_stream.exs

# Live CLI demo (requires authenticated codex CLI or CODEX_API_KEY)
mix run examples/live_cli_demo.exs "What is the capital of France?"

# Live Codex CLI passthrough helpers
mix run examples/live_cli_passthrough.exs completion zsh

# Live PTY-backed prompt-mode root session
mix run examples/live_cli_session.exs "Summarize this repository in three bullets."

Realtime Voice Interactions

For bidirectional voice interactions using the OpenAI Realtime API:

Auth precedence for realtime/voice API keys is: CODEX_API_KEY -> auth.json OPENAI_API_KEY -> OPENAI_API_KEY.

alias Codex.Realtime

# Create a realtime agent
agent = Realtime.agent(
  name: "VoiceAssistant",
  instructions: "You are a helpful voice assistant. Keep responses brief."
)

# Configure session options
config = %Codex.Realtime.Config.RunConfig{
  model_settings: %Codex.Realtime.Config.SessionModelSettings{
    voice: "alloy",
    turn_detection: %Codex.Realtime.Config.TurnDetectionConfig{
      type: :semantic_vad,
      eagerness: :medium
    }
  }
}

# Start a realtime session
{:ok, session} = Realtime.run(agent, config: config)

# Subscribe to events
Realtime.subscribe(session, self())

# Send audio and receive responses (commit on final chunk)
Realtime.send_audio(session, audio_data, commit: true)

Realtime.Session also traps linked WebSocket exits and keeps processing other session messages while tool calls are running.

Voice Pipeline (Non-Realtime)

For STT -> Workflow -> TTS processing:

alias Codex.Voice.{Pipeline, SimpleWorkflow, Config}

# Create a simple workflow
workflow = SimpleWorkflow.new(
  fn text -> ["You said: #{text}. How can I help?"] end,
  greeting: "Hello! I'm ready to listen."
)

# Configure the pipeline
config = %Config{
  workflow_name: "VoiceDemo",
  tts_settings: %Config.TTSSettings{voice: :nova}
}

# Create and run the pipeline
{:ok, pipeline} = Pipeline.start_link(workflow: workflow, config: config)
{:ok, result} = Pipeline.run(pipeline, audio_input)

# Process streamed audio output
for event <- result do
  case event do
    %Codex.Voice.Events.VoiceStreamEventAudio{data: data} ->
      # Handle audio chunk
      play_audio(data)
    _ -> :ok
  end
end

See examples/realtime_*.exs and examples/voice_*.exs for comprehensive demos.

Resuming Threads

Threads are persisted in ~/.codex/sessions. Resume previous conversations:

thread_id = "thread_abc123"
{:ok, thread} = Codex.resume_thread(thread_id)

{:ok, result} = Codex.Thread.run(thread, "Continue from where we left off")

Resume the most recent session (equivalent to codex exec resume --last):

{:ok, thread} = Codex.resume_thread(:last)
{:ok, result} = Codex.Thread.run(thread, "Continue from where we left off")

Session Helpers

The CLI writes session logs under ~/.codex/sessions. The SDK can list them and apply or undo diffs locally:

{:ok, sessions} = Codex.Sessions.list_sessions()

{:ok, result} = Codex.Sessions.apply(diff, cwd: "/path/to/repo")
{:ok, _undo} = Codex.Sessions.undo(ghost_snapshot, cwd: "/path/to/repo")

Configuration Options

# Codex-level options
{:ok, codex_options} =
  Codex.Options.new(
    api_key: System.fetch_env!("CODEX_API_KEY"),
    codex_path_override: "/custom/path/to/codex",
    telemetry_prefix: [:codex, :sdk],
    model: "o1",
    reasoning_effort: :high,  # :none | :minimal | :low | :medium | :high | :xhigh
    model_personality: :friendly,
    review_model: Codex.Models.default_model(),
    tool_output_token_limit: 512,
    history: %{persistence: "local", max_bytes: 1_000_000},
    config: %{"model_reasoning_summary" => "concise"}  # global --config baseline
  )

# Thread-level options
{:ok, thread_options} =
  Codex.Thread.Options.new(
    metadata: %{project: "codex_sdk"},
    labels: %{environment: "dev"},
    auto_run: true,
    sandbox: :strict,
    approval_timeout_ms: 45_000,
    web_search_mode: :cached,  # :disabled | :cached | :live (explicit :disabled forces disable override)
    personality: :pragmatic,   # :friendly | :pragmatic | :none (works consistently on exec/app-server)
    collaboration_mode: :plan  # :plan | :pair_programming | :code | :default | :execute | :custom (app-server)
  )

{:ok, thread} = Codex.start_thread(codex_options, thread_options)

# Run-level options (validated by Codex.RunConfig.new/1)
run_options = %{
  run_config: %{
    auto_previous_response_id: true
  }
}

{:ok, result} = Codex.Thread.run(thread, "Your prompt", run_options)
IO.inspect(result.last_response_id)
# Note: last_response_id remains nil until codex exec emits response_id fields.

# Turn-level options
turn_options = %{output_schema: my_json_schema, personality: :friendly}

{:ok, result} = Codex.Thread.run(thread, "Your prompt", turn_options)

# Exec controls: inject env, set cancellation token/timeout/idle timeout (forwarded to codex exec)
turn_options = %{
  env: %{"CODEX_DEMO_ENV" => "from-sdk"},
  cancellation_token: "demo-token-123",
  timeout_ms: 120_000,
  stream_idle_timeout_ms: 300_000
}

# The SDK also sets CODEX_INTERNAL_ORIGINATOR_OVERRIDE=codex_sdk_elixir
# unless you provide your own value in `env`.

{:ok, stream} =
  Codex.Thread.run_streamed(thread, "List three files and echo $CODEX_DEMO_ENV", turn_options)

# Opt-in retry and rate limit handling
{:ok, thread_opts} =
  Codex.Thread.Options.new(
    retry: true,
    retry_opts: [max_attempts: 3],
    rate_limit: true,
    rate_limit_opts: [max_attempts: 3]
  )

Config Overrides

Options-level, thread-level, and turn-level config overrides are forwarded as --config key=value flags to the Codex CLI (exec transport). For app-server transport, typed derived settings plus options-level config overrides are merged into the structured config payload when unset. Four layers of precedence apply for exec — later wins:

Options-level global — Codex.Options.new(config: ...)
Derived — automatically generated from typed Codex.Options and Codex.Thread.Options fields
Thread-level — Codex.Thread.Options.config_overrides
Turn-level — config_overrides in turn opts passed to Thread.run/3

Nested maps are auto-flattened to dotted-path keys:

# These two are equivalent:
config_overrides: %{"features" => %{"web_search_request" => true}}
config_overrides: [{"features.web_search_request", true}]

Override values are validated at runtime and must be TOML-compatible primitives: strings, booleans, integers/floats, arrays, and nested maps. Unsupported values (nil, tuples, PIDs, functions, etc.) return an error before the CLI is invoked.

When you explicitly disable web search (web_search_enabled: false or web_search_mode: :disabled), the SDK emits web_search="disabled" so that thread-level intent overrides existing CLI config. When you leave defaults untouched, the SDK now mirrors current Codex CLI behavior: cached web search for normal local runs, and live web search when you opt into full-access sandboxing (:danger_full_access, :permissive, or dangerously_bypass_approvals_and_sandbox: true).

Approval Hooks

Codex ships with approval policies and hooks so you can review potentially destructive actions before the agent executes them. Policies are provided per-thread:

policy = Codex.Approvals.StaticPolicy.deny(reason: "manual review required")

{:ok, thread_opts} =
  Codex.Thread.Options.new(
    sandbox: :strict,
    approval_policy: policy,
    approval_timeout_ms: 60_000
  )

{:ok, thread} = Codex.start_thread(%Codex.Options{}, thread_opts)

To integrate with external workflow tools, implement the Codex.Approvals.Hook behaviour and set it as the approval_hook:

defmodule MyApp.ApprovalHook do
  @behaviour Codex.Approvals.Hook

  def review_tool(event, context, _opts) do
    # Route to Slack/Jira/etc. and await a decision
    if MyApp.RiskEngine.requires_manual_review?(event, context) do
      {:deny, "pending review"}
    else
      :allow
    end
  end
end

{:ok, thread_opts} = Codex.Thread.Options.new(approval_hook: MyApp.ApprovalHook)
{:ok, thread} = Codex.start_thread(%Codex.Options{}, thread_opts)

Hooks can be synchronous or async (see Codex.Approvals.Hook for callback semantics), and all decisions emit telemetry so you can audit approvals externally.

Codex respects upstream safe-command markers: tool events flagged with requires_approval: false bypass approval gating automatically, keeping low-risk workspace actions fast while still blocking requests that require review.

For app-server file-change approvals, hooks can return {:allow, grant_root: "/path"} to accept the proposed root for the current session.

App-server permission approvals use structured grant payloads rather than string decisions. Hooks can implement review_permissions/3 and return :allow, {:allow, permissions: ..., scope: :turn | :session}, or {:deny, reason}. App-server streams now also surface %Codex.Events.GuardianApprovalReviewStarted{}, %Codex.Events.GuardianApprovalReviewCompleted{}, and %Codex.Events.ServerRequestResolved{} when the connected Codex build emits guardian review and request-resolution notifications. Use approvals_reviewer: :user | :guardian_subagent on thread options to control upstream review routing. The SDK also emits %Codex.Events.CommandApprovalRequested{} and %Codex.Events.FileApprovalRequested{} for app-server request approvals, preserving upstream fields such as approval_id, command_actions, network_approval_context, additional_permissions, available_decisions, and grant_root in normalized snake_case. These app-server approval fields are experimental upstream, so connect with experimental_api: true before using them. For live request-permissions flows, use a granular approval policy with request_permissions: true, but note that upstream keeps request_permissions_tool, exec_permission_approvals, and guardian_approval disabled by default on stock CLI installs. The SDK accepts both the local inline shape (%{type: :granular, request_permissions: true}) and the upstream external-tagged shape (%{granular: %{request_permissions: true}}); malformed granular maps now fail fast instead of being silently dropped.

Tool-call events can also arrive pre-approved via approved_by_policy (or approved) from the CLI; the SDK mirrors that bypass and skips hooks while still emitting telemetry. Sandbox warnings are normalized so Windows paths dedupe cleanly (e.g., C:/Temp and C:\\Temp coalesce). See examples/sandbox_warnings_and_approval_bypass.exs for a runnable walkthrough.

File Attachments & Registries

Stage attachments once and reuse them across turns or threads with the built-in registry:

{:ok, attachment} = Codex.Files.stage("reports/summary.md", ttl_ms: :infinity)

thread_opts =
  %Codex.Thread.Options{}
  |> Codex.Files.attach(attachment)

{:ok, thread} = Codex.start_thread(%Codex.Options{}, thread_opts)

Query Codex.Files.metrics/0 for staging stats and force cleanup with Codex.Files.force_cleanup/0. Codex.Files.force_cleanup/0, Codex.Files.reset!/0, and Codex.Files.metrics/0 return {:error, reason} if the registry is unavailable. Use Codex.Files.list_staged_result/0 for explicit {:ok, list} | {:error, reason} responses; Codex.Files.list_staged/0 remains available as a compatibility helper that falls back to [] on startup errors. Staged files are runtime-scoped; the registry clears the staging directory on startup, so re-stage attachments after restarts.

MCP Tool Discovery

The SDK provides MCP client helpers for discovering and invoking tools from MCP servers:

# Connect to a stdio MCP server
{:ok, transport} =
  Codex.MCP.Transport.Stdio.start_link(
    command: "npx",
    args: ["-y", "mcp-server"]
  )

{:ok, client} =
  Codex.MCP.Client.initialize(
    {Codex.MCP.Transport.Stdio, transport},
    client: "codex-elixir",
    version: "0.1.0",
    server_name: "my_server"
  )

# List tools with filtering
{:ok, tools, client} = Codex.MCP.Client.list_tools(client,
  allow: ["read_file", "write_file"],
  deny: ["dangerous_tool"]
)

# List tools with qualified names (mcp__server__tool format)
{:ok, tools, client} = Codex.MCP.Client.list_tools(client, qualify?: true)

# Each tool includes:
# - "name" - original tool name
# - "qualified_name" - fully qualified name (e.g., "mcp__my_server__read_file")
# - "server_name" - server identifier

Codex.MCP.Transport.StreamableHTTP provides JSON-RPC over HTTP with bearer/OAuth auth support for remote MCP servers. Transport failures are normalized to {:error, reason} tuples.

Tool name qualification now sanitizes each server/tool component to ASCII alphanumerics plus _ and - before joining them for OpenAI-facing tool names. Original MCP server/tool names are preserved for actual MCP calls. Names exceeding 64 characters are truncated with a SHA1 hash suffix for disambiguation:

Codex.MCP.Client.qualify_tool_name("server1", "tool_a")
#=> "mcp__server1__tool_a"

Codex.MCP.Client.qualify_tool_name("server.one", "tool.two-three")
#=> "mcp__server_one__tool_two-three"

# Long names are truncated with SHA1 suffix
Codex.MCP.Client.qualify_tool_name("srv", String.duplicate("a", 80))
#=> 64-character string with SHA1 hash suffix

Results are cached by default; bypass with cache?: false. See Codex.MCP.Client for full documentation and examples/live_mcp_and_sessions.exs for a runnable demo.

Shell Hosted Tool

The SDK provides a fully-featured shell command execution tool with approval integration, timeout handling, and output truncation:

alias Codex.Tools
alias Codex.Tools.ShellTool

# Register with default settings (60s timeout, 10KB max output)
{:ok, _} = Tools.register(ShellTool)

# Execute a simple command
{:ok, result} = Tools.invoke("shell", %{"command" => ["ls", "-la"]}, %{})
# => %{"output" => "...", "exit_code" => 0, "success" => true}

# With working directory
{:ok, result} = Tools.invoke("shell", %{"command" => ["pwd"], "workdir" => "/tmp"}, %{})

# With custom timeout and output limits
{:ok, _} = Tools.register(ShellTool,
  timeout_ms: 30_000,
  max_output_bytes: 5000
)

# With approval callback for sensitive commands
approval = fn cmd, _ctx ->
  if String.contains?(cmd, "rm"), do: {:deny, "rm not allowed"}, else: :ok
end

{:ok, _} = Tools.register(ShellTool, approval: approval)
{:error, {:approval_denied, "rm not allowed"}} =
  Tools.invoke("shell", %{"command" => ["rm", "file"]}, %{})

For custom execution, provide a custom executor:

custom_executor = fn %{"command" => cmd}, _ctx, _meta ->
  formatted = if is_list(cmd), do: Enum.join(cmd, " "), else: cmd
  {:ok, %{"output" => "custom: #{formatted}", "exit_code" => 0}}
end

{:ok, _} = Tools.register(ShellTool, executor: custom_executor)

For string shell scripts, use the shell_command tool:

alias Codex.Tools.ShellCommandTool

{:ok, _} = Tools.register(ShellCommandTool)
{:ok, result} = Tools.invoke("shell_command", %{"command" => "ls -la", "workdir" => "/tmp"}, %{})

Additional hosted tools include write_stdin (unified exec sessions via app-server) and view_image (local image attachments gated by features.view_image_tool or Thread.Options.view_image_tool_enabled).

See examples/shell_tool.exs for a complete demonstration.

FileSearch Hosted Tool

The SDK provides a local filesystem search tool with glob pattern matching and content search capabilities:

alias Codex.Tools
alias Codex.Tools.FileSearchTool

# Register with default settings
{:ok, _} = Tools.register(FileSearchTool)

# Find all Elixir files recursively
{:ok, result} = Tools.invoke("file_search", %{"pattern" => "lib/**/*.ex"}, %{})
# => %{"count" => 42, "files" => [%{"path" => "lib/foo.ex"}, ...]}

# Search file content with regex
{:ok, result} = Tools.invoke("file_search", %{
  "pattern" => "**/*.ex",
  "content" => "defmodule"
}, %{})
# => %{"count" => 10, "files" => [%{"path" => "lib/foo.ex", "matches" => [...]}]}

# Case-insensitive content search
{:ok, result} = Tools.invoke("file_search", %{
  "pattern" => "**/*.ex",
  "content" => "ERROR",
  "case_sensitive" => false
}, %{})

# Limit results
{:ok, result} = Tools.invoke("file_search", %{
  "pattern" => "**/*",
  "max_results" => 20
}, %{})

# Custom base path
{:ok, _} = Tools.register(FileSearchTool, base_path: "/project")

Supported glob patterns:

*.ex - All .ex files in base directory
**/*.ex - All .ex files recursively
lib/**/*.{ex,exs} - All Elixir files under lib/

See examples/file_search_tool.exs for more examples.

MCP Tool Invocation

Invoke tools on MCP servers with built-in retry logic, approval callbacks, and telemetry:

# Basic invocation with default retries (3) and exponential backoff
{:ok, result} = Codex.MCP.Client.call_tool(client, "echo", %{"text" => "hello"})

# Custom retry and timeout settings
{:ok, result} = Codex.MCP.Client.call_tool(client, "fetch", %{"url" => url},
  retries: 5,
  timeout_ms: 30_000,
  backoff: fn attempt -> Process.sleep(attempt * 200) end
)

# With approval callback (for sensitive operations)
{:ok, result} = Codex.MCP.Client.call_tool(client, "write_file", args,
  approval: fn tool, args, context ->
    if authorized?(context.user, tool), do: :ok, else: {:deny, "unauthorized"}
  end,
  context: %{user: current_user}
)

Telemetry events are emitted for observability:

[:codex, :mcp, :tool_call, :start] - When a call begins
[:codex, :mcp, :tool_call, :success] - On successful completion
[:codex, :mcp, :tool_call, :failure] - On failure after retries exhausted

Custom Prompts and Skills

List and expand custom prompts from $CODEX_HOME/prompts, and load skills when features.skills is enabled:

{:ok, prompts} = Codex.Prompts.list()
{:ok, expanded} = Codex.Prompts.expand(Enum.at(prompts, 0), "FILE=lib/app.ex")

{:ok, conn} = Codex.AppServer.connect(codex_opts)
{:ok, %{"data" => skills}} = Codex.Skills.list(conn, skills_enabled: true)
{:ok, content} = Codex.Skills.load(hd(hd(skills)["skills"]), skills_enabled: true)

Retry Logic

The SDK provides comprehensive retry utilities via Codex.Retry for handling transient failures:

alias Codex.Retry

# Basic retry with defaults (4 attempts, exponential backoff, 200ms base delay)
{:ok, result} = Retry.with_retry(fn -> make_api_call() end)

# Custom configuration
{:ok, result} = Retry.with_retry(
  fn -> risky_operation() end,
  max_attempts: 5,
  base_delay_ms: 100,
  max_delay_ms: 5_000,
  strategy: :exponential,
  jitter: true,
  on_retry: fn attempt, error ->
    Logger.warning("Retry #{attempt}: #{inspect(error)}")
  end
)

# Different backoff strategies
Retry.with_retry(fun, strategy: :linear)      # 100, 200, 300, 400ms...
Retry.with_retry(fun, strategy: :constant)    # 100, 100, 100, 100ms...
Retry.with_retry(fun, strategy: :exponential) # 100, 200, 400, 800ms... (default)

# Custom backoff function
Retry.with_retry(fun, strategy: fn attempt -> attempt * 50 end)

# Custom retry predicate
Retry.with_retry(fun, retry_if: fn
  :my_transient_error -> true
  _ -> false
end)

# Stream retry (retries entire stream creation on failure)
stream = Retry.with_stream_retry(fn -> make_streaming_request() end)
Enum.each(stream, &process_item/1)

Default retryable errors include: :timeout, :econnrefused, :econnreset, :closed, :nxdomain, 5xx HTTP errors, 429 rate limits, stream errors, and Codex.TransportError with retryable?: true. See examples/retry_example.exs for more patterns.

Telemetry & OTLP Exporting

OpenTelemetry exporting is disabled by default. To ship traces/metrics to a collector, set CODEX_OTLP_ENABLE=1 along with the endpoint (and optional headers) before starting your application:

export CODEX_OTLP_ENABLE=1
export CODEX_OTLP_ENDPOINT="https://otel.example.com:4318"
export CODEX_OTLP_HEADERS="authorization=Bearer abc123"

mix run examples/basic_usage.exs

When the flag is not set (default), the SDK runs without booting the OTLP exporter—avoiding tls_certificate_check warnings on systems without the helper installed.

The Codex CLI (codex-rs) has its own OpenTelemetry log exporter, configured separately via $CODEX_HOME/config.toml (default ~/.codex/config.toml) under [otel]. This is independent of the Elixir SDK exporter above.

[otel]
environment = "staging"
exporter = "otlp-grpc"
log_user_prompt = false

[otel.exporter."otlp-grpc"]
endpoint = "https://otel.example.com:4317"

See codex/docs/config.md for the full upstream reference. To point Codex at an isolated config directory from the SDK, pass env: %{"CODEX_HOME" => "/path/to/codex_home"} in turn options for exec transport, or Codex.AppServer.connect(codex_opts, process_env: %{"CODEX_HOME" => ...}) for a managed app-server child.

Architecture

The SDK follows a layered architecture built on OTP principles:

Codex: Main entry point for starting and resuming threads
Codex.Thread: Manages individual conversation threads and turn execution
Codex.Exec: GenServer that manages the codex-rs OS process via Port
Codex.Events: Comprehensive event type definitions
Codex.Items: Thread item structs (messages, commands, file changes, etc.)
Codex.Options: Configuration structs for all levels
Codex.Config.Overrides: Config override serialization, nested map flattening, and TOML value validation
Codex.Runtime.Erlexec: Unified erlexec startup shared across subprocess modules
Codex.Runtime.Env: Subprocess environment construction (sets CODEX_INTERNAL_ORIGINATOR_OVERRIDE)
Codex.Config.BaseURL: Base URL resolution with option → env → default precedence
Codex.Config.OptionNormalizers: Shared reasoning summary, verbosity, and history validation
Codex.Realtime: Bidirectional voice via OpenAI Realtime API (WebSocket)
Codex.Voice: Non-realtime STT → Workflow → TTS pipeline
Codex.OutputSchemaFile: Helper for managing JSON schema temporary files

Process Model

┌─────────────┐
│   Client    │
└──────┬──────┘
       │
       ▼
┌─────────────────┐
│ Codex.Thread    │  (manages turn state)
└────────┬────────┘
         │
         ▼
┌──────────────────┐
│  Codex.Exec      │  (GenServer - manages codex-rs process)
└────────┬─────────┘
         │
         ▼
┌──────────────────┐
│   Port (stdin/   │  (IPC with codex-rs via JSONL)
│    stdout)       │
└────────┬─────────┘
         │
         ▼
┌──────────────────┐
│   codex-rs       │  (OpenAI's Codex CLI)
└──────────────────┘

Event Types

The SDK provides structured events for all Codex operations:

Thread Events

ThreadStarted - New thread initialized with thread_id
TurnStarted - Agent begins processing a prompt
TurnCompleted - Turn finished with usage statistics
TurnFailed - Turn encountered an error

Session and Control Events

SessionConfigured - Session bootstrap details and initial messages
ContextCompacted - Compaction summary after auto-compaction
ThreadRolledBack - Thread rollback summary
RequestUserInput - Tool-driven user input request
ElicitationRequest - MCP elicitation request
UndoStarted / UndoCompleted - Undo lifecycle events
EnteredReviewMode / ExitedReviewMode - Review mode lifecycle updates
ConfigWarning - Config warnings emitted by the server

Item Events

ItemStarted - New item added to thread
ItemUpdated - Item state changed
ItemCompleted - Item reached terminal state

Item Types

AgentMessage - Text or JSON response from the agent
Reasoning - Agent's reasoning summary
CommandExecution - Shell command execution with output
FileChange - File modifications (add, update, delete)
McpToolCall - Model Context Protocol tool invocations
WebSearch - Web search queries and results
TodoList - Agent's running task list
Error - Non-fatal error items

Examples

See the examples/ directory for comprehensive demonstrations. A quick index:

basic_usage.exs - First turn, follow-ups, and result inspection
streaming.exs - Real-time turn streaming (progressive and stateful modes)
structured_output.exs - JSON schema enforcement and decoding helpers
conversation_and_resume.exs - Persisting, resuming, and replaying conversations
concurrency_and_collaboration.exs - Multi-turn concurrency patterns
approval_hook_example.exs - Custom approval hook wiring and telemetry inspection
sandbox_warnings_and_approval_bypass.exs - Normalized sandbox warnings and policy-approved bypass demo
tool_bridging_auto_run.exs - Auto-run tool bridging with retries and failure reporting
live_cli_demo.exs - Live CLI walkthrough (uses CLI auth)
live_cli_passthrough.exs - Direct wrappers for completion, features, login status, and arbitrary raw codex commands
live_cli_session.exs - PTY-backed root codex prompt mode via Codex.CLI.interactive/2
live_oauth_login.exs - Native OAuth status/login/refresh demo with an isolated temporary CODEX_HOME; prints the browser URL before waiting, supports --browser, --device, and --no-browser, and can optionally show memory-mode app-server auth
live_app_server_approvals.exs - Command/file/permissions approvals over app-server, using a disposable workspace plus temporary CODEX_HOME to exercise under-development approval features without mutating your real settings
live_collaboration_modes.exs - experimentalApi collaboration mode presets and a live turn that uses the server-advertised preset settings (falling back only when the server omits a field), with an explicit skip when the connected build rejects or omits collaborationMode/list
live_subagent_host_controls.exs - Live subagent workflow over app-server that enables features.multi_agent, exercises the full Codex.Subagents helper surface, and drives spawn_agent, send_input, resume_agent, wait, and close_agent
live_personality.exs - Personality overrides (friendly, pragmatic, none)
live_config_overrides.exs - Nested config override auto-flattening plus layered openai_base_url / model_providers parity demo
live_options_config_overrides.exs - Options-level global config overrides, precedence, validation, and reserved provider notes
live_thread_management.exs - Thread read/fork/rollback/loaded list workflows
live_web_search_modes.exs - Web search mode toggles with disabled/live validation and cached-mode event reporting
live_rate_limits.exs - Rate limit snapshot reporting from token usage events
live_session_walkthrough.exs, live_exec_controls.exs, live_tooling_stream.exs, live_telemetry_stream.exs, live_usage_and_compaction.exs - Additional live examples that stream, track usage, and show approvals/tooling flows
live_realtime_voice.exs - Full realtime voice interaction demo with event handling and CA env notes
realtime_basic.exs, realtime_tools.exs, realtime_handoffs.exs - Realtime API examples for sessions, tools, handoffs, and CA env notes
voice_pipeline.exs, voice_multi_turn.exs, voice_with_agent.exs - Voice pipeline examples for STT/TTS workflows with CA env notes

Run examples with:

mix run examples/basic_usage.exs

# Live CLI example (requires authenticated codex CLI)
mix run examples/live_cli_demo.exs "What is the capital of France?"

# Run all live examples in sequence
./examples/run_all.sh

Documentation

API Reference: Generated docs available via mix docs or on HexDocs
Changelog: CHANGELOG.md summarises release history
Repo Appendix: sentience/ contains optional repo folklore documents

License

This project is licensed under the MIT License - see the LICENSE file for details.

Acknowledgments

OpenAI team for the Codex CLI and agent technology
Elixir community for excellent OTP tooling and libraries
Gemini Ex for SDK inspiration

Related Projects

OpenAI Codex - The official Codex CLI
Codex TypeScript SDK - Official TypeScript SDK

Made with ❤️ and Elixir

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assets		assets
config		config
docs		docs
examples		examples
guides		guides
integration/fixtures		integration/fixtures
lib		lib
priv		priv
scripts		scripts
sentience		sentience
test		test
.formatter.exs		.formatter.exs
.gitignore		.gitignore
AGENTS.md		AGENTS.md
CHANGELOG.md		CHANGELOG.md
LICENSE		LICENSE
README.md		README.md
VERSION		VERSION
approval_demo.txt		approval_demo.txt
mix.exs		mix.exs
mix.lock		mix.lock

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Codex SDK for Elixir

Features

Installation

Prerequisites

Quick Start

Basic Usage

App-server Transport (Optional)

Raw CLI Passthrough and Interactive Sessions

Streaming Responses

Structured Output

Runnable Examples

Realtime Voice Interactions

Voice Pipeline (Non-Realtime)

Resuming Threads

Session Helpers

Configuration Options

Config Overrides

Approval Hooks

File Attachments & Registries

MCP Tool Discovery

Shell Hosted Tool

FileSearch Hosted Tool

MCP Tool Invocation

Custom Prompts and Skills

Retry Logic

Telemetry & OTLP Exporting

Architecture

Process Model

Event Types

Thread Events

Session and Control Events

Item Events

Item Types

Examples

Documentation

License

Acknowledgments

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