Codex App Server

Codex app-server is the interface Codex uses to power rich clients (for example, the Codex VS Code extension). Use it when you want a deep integration inside your own product: authentication, conversation history, approvals, and streamed agent events. The app-server implementation is open source in the Codex GitHub repository (openai/codex/codex-rs/app-server). See the Open Source page for the full list of open-source Codex components.

If you are automating jobs or running Codex in CI, use the Codex SDK instead.

Protocol

Like MCP, codex app-server supports bidirectional communication using JSON-RPC 2.0 messages (with the "jsonrpc":"2.0" header omitted on the wire).

Supported transports:

stdio (--listen stdio://, default): newline-delimited JSON (JSONL).
websocket (--listen ws://IP:PORT, experimental): one JSON-RPC message per WebSocket text frame.

In WebSocket mode, app-server uses bounded queues. When request ingress is full, the server rejects new requests with JSON-RPC error code -32001 and message "Server overloaded; retry later." Clients should retry with an exponentially increasing delay and jitter.

Message schema

Requests include method, params, and id:

{ "method": "thread/start", "id": 10, "params": { "model": "gpt-5.1-codex" } }

Responses echo the id with either result or error:

{ "id": 10, "result": { "thread": { "id": "thr_123" } } }

{ "id": 10, "error": { "code": 123, "message": "Something went wrong" } }

Notifications omit id and use only method and params:

{ "method": "turn/started", "params": { "turn": { "id": "turn_456" } } }

You can generate a TypeScript schema or a JSON Schema bundle from the CLI. Each output is specific to the Codex version you ran, so the generated artifacts match that version exactly:

codex app-server generate-ts --out ./schemas
codex app-server generate-json-schema --out ./schemas

Getting started

Start the server with codex app-server (default stdio transport) or codex app-server --listen ws://127.0.0.1:4500 (experimental WebSocket transport).
Connect a client over the selected transport, then send initialize followed by the initialized notification.
Start a thread and a turn, then keep reading notifications from the active transport stream.

Example (Node.js / TypeScript):

import { spawn } from "node:child_process";
import readline from "node:readline";

const proc = spawn("codex", ["app-server"], {
  stdio: ["pipe", "pipe", "inherit"],
});
const rl = readline.createInterface({ input: proc.stdout });

const send = (message: unknown) => {
  proc.stdin.write(`${JSON.stringify(message)}\n`);
};

let threadId: string | null = null;

rl.on("line", (line) => {
  const msg = JSON.parse(line) as any;
  console.log("server:", msg);

  if (msg.id === 1 && msg.result?.thread?.id && !threadId) {
    threadId = msg.result.thread.id;
    send({
      method: "turn/start",
      id: 2,
      params: {
        threadId,
        input: [{ type: "text", text: "Summarize this repo." }],
      },
    });
  }
});

send({
  method: "initialize",
  id: 0,
  params: {
    clientInfo: {
      name: "my_product",
      title: "My Product",
      version: "0.1.0",
    },
  },
});
send({ method: "initialized", params: {} });
send({ method: "thread/start", id: 1, params: { model: "gpt-5.1-codex" } });

Core primitives

Thread: A conversation between a user and the Codex agent. Threads contain turns.
Turn: A single user request and the agent work that follows. Turns contain items and stream incremental updates.
Item: A unit of input or output (user message, agent message, command runs, file change, tool call, and more).

Use the thread APIs to create, list, or archive conversations. Drive a conversation with turn APIs and stream progress via turn notifications.

Lifecycle overview

Initialize once per connection: Immediately after opening a transport connection, send an initialize request with your client metadata, then emit initialized. The server rejects any request on that connection before this handshake.
Start (or resume) a thread: Call thread/start for a new conversation, thread/resume to continue an existing one, or thread/fork to branch history into a new thread id.
Begin a turn: Call turn/start with the target threadId and user input. Optional fields override model, personality, cwd, sandbox policy, and more.
Steer an active turn: Call turn/steer to append user input to the currently in-flight turn without creating a new turn.
Stream events: After turn/start, keep reading notifications on stdout: item/started, item/completed, item/agentMessage/delta, tool progress, and other updates.
Finish the turn: The server emits turn/completed with final status when the model finishes or after a turn/interrupt cancellation.

Initialization

Clients must send a single initialize request per transport connection before invoking any other method on that connection, then acknowledge with an initialized notification. Requests sent before initialization receive a Not initialized error, and repeated initialize calls on the same connection return Already initialized.

The server returns the user agent string it will present to upstream services. Set clientInfo to identify your integration.

initialize.params.capabilities also supports per-connection notification opt-out via optOutNotificationMethods, which is a list of exact method names to suppress for that connection. Matching is exact (no wildcards/prefixes). Unknown method names are accepted and ignored.

Important: Use clientInfo.name to identify your client for the OpenAI Compliance Logs Platform. If you are developing a new Codex integration intended for enterprise use, please contact OpenAI to get it added to a known clients list. For more context, see the Codex logs reference.

Example (from the Codex VS Code extension):

{
  "method": "initialize",
  "id": 0,
  "params": {
    "clientInfo": {
      "name": "codex_vscode",
      "title": "Codex VS Code Extension",
      "version": "0.1.0"
    }
  }
}

Example with notification opt-out:

{
  "method": "initialize",
  "id": 1,
  "params": {
    "clientInfo": {
      "name": "my_client",
      "title": "My Client",
      "version": "0.1.0"
    },
    "capabilities": {
      "experimentalApi": true,
      "optOutNotificationMethods": [
        "codex/event/session_configured",
        "item/agentMessage/delta"
      ]
    }
  }
}

Experimental API opt-in

Some app-server methods and fields are intentionally gated behind experimentalApi capability.

Omit capabilities (or set experimentalApi to false) to stay on the stable API surface, and the server rejects experimental methods/fields.
Set capabilities.experimentalApi to true to enable experimental methods and fields.

{
  "method": "initialize",
  "id": 1,
  "params": {
    "clientInfo": {
      "name": "my_client",
      "title": "My Client",
      "version": "0.1.0"
    },
    "capabilities": {
      "experimentalApi": true
    }
  }
}

If a client sends an experimental method or field without opting in, app-server rejects it with:

<descriptor> requires experimentalApi capability

API overview

thread/start - create a new thread; emits thread/started and automatically subscribes you to turn/item events for that thread.
thread/resume - reopen an existing thread by id so later turn/start calls append to it.
thread/fork - fork a thread into a new thread id by copying stored history; emits thread/started for the new thread.
thread/read - read a stored thread by id without resuming it; set includeTurns to return full turn history.
thread/list - page through stored thread logs; supports cursor-based pagination plus modelProviders, sourceKinds, archived, and cwd filters.
thread/loaded/list - list the thread ids currently loaded in memory.
thread/archive - move a thread’s log file into the archived directory; returns {} on success.
thread/unarchive - restore an archived thread rollout back into the active sessions directory; returns the restored thread.
thread/compact/start - trigger conversation history compaction for a thread; returns {} immediately while progress streams via turn/* and item/* notifications.
thread/rollback - drop the last N turns from the in-memory context and persist a rollback marker; returns the updated thread.
turn/start - add user input to a thread and begin Codex generation; responds with the initial turn and streams events. For collaborationMode, settings.developer_instructions: null means “use built-in instructions for the selected mode.”
turn/steer - append user input to the active in-flight turn for a thread; returns the accepted turnId.
turn/interrupt - request cancellation of an in-flight turn; success is {} and the turn ends with status: "interrupted".
review/start - kick off the Codex reviewer for a thread; emits enteredReviewMode and exitedReviewMode items.
command/exec - run a single command under the server sandbox without starting a thread/turn.
model/list - list available models (set includeHidden: true to include entries with hidden: true) with effort options, optional upgrade, and inputModalities.
experimentalFeature/list - list feature flags with lifecycle stage metadata and cursor pagination.
collaborationMode/list - list collaboration mode presets (experimental, no pagination).
skills/list - list skills for one or more cwd values (supports forceReload and optional perCwdExtraUserRoots).
app/list - list available apps (connectors) with pagination plus accessibility/enabled metadata.
skills/config/write - enable or disable skills by path.
mcpServer/oauth/login - start an OAuth login for a configured MCP server; returns an authorization URL and emits mcpServer/oauthLogin/completed on completion.
tool/requestUserInput - prompt the user with 1-3 short questions for a tool call (experimental); questions can set isOther for a free-form option.
config/mcpServer/reload - reload MCP server configuration from disk and queue a refresh for loaded threads.
mcpServerStatus/list - list MCP servers, tools, resources, and auth status (cursor + limit pagination).
feedback/upload - submit a feedback report (classification + optional reason/logs + conversation id).
config/read - fetch the effective configuration on disk after resolving configuration layering.
config/value/write - write a single configuration key/value to the user’s config.toml on disk.
config/batchWrite - apply configuration edits atomically to the user’s config.toml on disk.
configRequirements/read - fetch requirements from requirements.toml and/or MDM, including allow-lists and residency requirements (or null if you haven’t set any up).

Models

List models (`model/list`)

Call model/list to discover available models and their capabilities before rendering model or personality selectors.

{ "method": "model/list", "id": 6, "params": { "limit": 20, "includeHidden": false } }
{ "id": 6, "result": {
  "data": [{
    "id": "gpt-5.2-codex",
    "model": "gpt-5.2-codex",
    "upgrade": "gpt-5.3-codex",
    "displayName": "GPT-5.2 Codex",
    "hidden": false,
    "defaultReasoningEffort": "medium",
    "reasoningEffort": [{
      "effort": "low",
      "description": "Lower latency"
    }],
    "inputModalities": ["text", "image"],
    "supportsPersonality": true,
    "isDefault": true
  }],
  "nextCursor": null
} }

Each model entry can include:

reasoningEffort - supported effort options for the model.
defaultReasoningEffort - suggested default effort for clients.
upgrade - optional recommended upgrade model id for migration prompts in clients.
hidden - whether the model is hidden from the default picker list.
inputModalities - supported input types for the model (for example text, image).
supportsPersonality - whether the model supports personality-specific instructions such as /personality.
isDefault - whether the model is the recommended default.

By default, model/list returns picker-visible models only. Set includeHidden: true if you need the full list and want to filter on the client side using hidden.

When inputModalities is missing (older model catalogs), treat it as ["text", "image"] for backward compatibility.

List experimental features (`experimentalFeature/list`)

Use this endpoint to discover feature flags with metadata and lifecycle stage:

{ "method": "experimentalFeature/list", "id": 7, "params": { "limit": 20 } }
{ "id": 7, "result": {
  "data": [{
    "name": "unified_exec",
    "stage": "beta",
    "displayName": "Unified exec",
    "description": "Use the unified PTY-backed execution tool.",
    "announcement": "Beta rollout for improved command execution reliability.",
    "enabled": false,
    "defaultEnabled": false
  }],
  "nextCursor": null
} }

stage can be beta, underDevelopment, stable, deprecated, or removed. For non-beta flags, displayName, description, and announcement may be null.

Threads

thread/read reads a stored thread without subscribing to it; set includeTurns to include turns.
thread/list supports cursor pagination plus modelProviders, sourceKinds, archived, and cwd filtering.
thread/loaded/list returns the thread IDs currently in memory.
thread/archive moves the thread’s persisted JSONL log into the archived directory.
thread/unarchive restores an archived thread rollout back into the active sessions directory.
thread/compact/start triggers compaction and returns {} immediately.
thread/rollback drops the last N turns from the in-memory context and records a rollback marker in the thread’s persisted JSONL log.

Start or resume a thread

Start a fresh thread when you need a new Codex conversation.

{ "method": "thread/start", "id": 10, "params": {
  "model": "gpt-5.1-codex",
  "cwd": "/Users/me/project",
  "approvalPolicy": "never",
  "sandbox": "workspaceWrite",
  "personality": "friendly"
} }
{ "id": 10, "result": {
  "thread": {
    "id": "thr_123",
    "preview": "",
    "modelProvider": "openai",
    "createdAt": 1730910000
  }
} }
{ "method": "thread/started", "params": { "thread": { "id": "thr_123" } } }

To continue a stored session, call thread/resume with the thread.id you recorded earlier. The response shape matches thread/start. You can also pass the same configuration overrides supported by thread/start, such as personality:

{ "method": "thread/resume", "id": 11, "params": {
  "threadId": "thr_123",
  "personality": "friendly"
} }
{ "id": 11, "result": { "thread": { "id": "thr_123" } } }

Resuming a thread doesn’t update thread.updatedAt (or the rollout file’s modified time) by itself. The timestamp updates when you start a turn.

If you mark an enabled MCP server as required in config and that server fails to initialize, thread/start and thread/resume fail instead of continuing without it.

dynamicTools on thread/start is an experimental field (requires capabilities.experimentalApi = true). Codex persists these dynamic tools in the thread rollout metadata and restores them on thread/resume when you don’t supply new dynamic tools.

If you resume with a different model than the one recorded in the rollout, Codex emits a warning and applies a one-time model-switch instruction on the next turn.

To branch from a stored session, call thread/fork with the thread.id. This creates a new thread id and emits a thread/started notification for it:

{ "method": "thread/fork", "id": 12, "params": { "threadId": "thr_123" } }
{ "id": 12, "result": { "thread": { "id": "thr_456" } } }
{ "method": "thread/started", "params": { "thread": { "id": "thr_456" } } }

Read a stored thread (without resuming)

Use thread/read when you want stored thread data but don’t want to resume the thread or subscribe to its events.

includeTurns - when true, the response includes the thread’s turns; when false or omitted, you get the thread summary only.

{ "method": "thread/read", "id": 19, "params": { "threadId": "thr_123", "includeTurns": true } }
{ "id": 19, "result": { "thread": { "id": "thr_123", "turns": [] } } }

Unlike thread/resume, thread/read doesn’t load the thread into memory or emit thread/started.

List threads (with pagination & filters)

thread/list lets you render a history UI. Results default to newest-first by createdAt. Filters apply before pagination. Pass any combination of:

cursor - opaque string from a prior response; omit for the first page.
limit - server defaults to a reasonable page size if unset.
sortKey - created_at (default) or updated_at.
modelProviders - restrict results to specific providers; unset, null, or an empty array includes all providers.
sourceKinds - restrict results to specific thread sources. When omitted or [], the server defaults to interactive sources only: cli and vscode.
archived - when true, list archived threads only. When false or omitted, list non-archived threads (default).
cwd - restrict results to threads whose session current working directory exactly matches this path.

sourceKinds accepts the following values:

cli
vscode
exec
appServer
subAgent
subAgentReview
subAgentCompact
subAgentThreadSpawn
subAgentOther
unknown

Example:

{ "method": "thread/list", "id": 20, "params": {
  "cursor": null,
  "limit": 25,
  "sortKey": "created_at"
} }
{ "id": 20, "result": {
  "data": [
    { "id": "thr_a", "preview": "Create a TUI", "modelProvider": "openai", "createdAt": 1730831111, "updatedAt": 1730831111 },
    { "id": "thr_b", "preview": "Fix tests", "modelProvider": "openai", "createdAt": 1730750000, "updatedAt": 1730750000 }
  ],
  "nextCursor": "opaque-token-or-null"
} }

When nextCursor is null, you have reached the final page.

List loaded threads

thread/loaded/list returns thread IDs currently loaded in memory.

{ "method": "thread/loaded/list", "id": 21 }
{ "id": 21, "result": { "data": ["thr_123", "thr_456"] } }

Archive a thread

Use thread/archive to move the persisted thread log (stored as a JSONL file on disk) into the archived sessions directory.

{ "method": "thread/archive", "id": 22, "params": { "threadId": "thr_b" } }
{ "id": 22, "result": {} }

Archived threads won’t appear in future calls to thread/list unless you pass archived: true.

Unarchive a thread

Use thread/unarchive to move an archived thread rollout back into the active sessions directory.

{ "method": "thread/unarchive", "id": 24, "params": { "threadId": "thr_b" } }
{ "id": 24, "result": { "thread": { "id": "thr_b" } } }

Trigger thread compaction

Use thread/compact/start to trigger manual history compaction for a thread. The request returns immediately with {}.

App-server emits progress as standard turn/* and item/* notifications on the same threadId, including a contextCompaction item lifecycle (item/started then item/completed).

{ "method": "thread/compact/start", "id": 25, "params": { "threadId": "thr_b" } }
{ "id": 25, "result": {} }

Turns

The input field accepts a list of items:

{ "type": "text", "text": "Explain this diff" }
{ "type": "image", "url": "https://.../design.png" }
{ "type": "localImage", "path": "/tmp/screenshot.png" }

You can override configuration settings per turn (model, effort, personality, cwd, sandbox policy, summary). When specified, these settings become the defaults for later turns on the same thread. outputSchema applies only to the current turn. For sandboxPolicy.type = "externalSandbox", set networkAccess to restricted or enabled; for workspaceWrite, networkAccess remains a boolean.

For turn/start.collaborationMode, settings.developer_instructions: null means “use built-in instructions for the selected mode” rather than clearing mode instructions.

Sandbox read access (`ReadOnlyAccess`)

sandboxPolicy supports explicit read-access controls:

readOnly: optional access ({ "type": "fullAccess" } by default, or restricted roots).
workspaceWrite: optional readOnlyAccess ({ "type": "fullAccess" } by default, or restricted roots).

Restricted read access shape:

{
  "type": "restricted",
  "includePlatformDefaults": true,
  "readableRoots": ["/Users/me/shared-read-only"]
}

Examples:

{ "type": "readOnly", "access": { "type": "fullAccess" } }

{
  "type": "workspaceWrite",
  "writableRoots": ["/Users/me/project"],
  "readOnlyAccess": {
    "type": "restricted",
    "includePlatformDefaults": true,
    "readableRoots": ["/Users/me/shared-read-only"]
  },
  "networkAccess": false
}

Start a turn

{ "method": "turn/start", "id": 30, "params": {
  "threadId": "thr_123",
  "input": [ { "type": "text", "text": "Run tests" } ],
  "cwd": "/Users/me/project",
  "approvalPolicy": "unlessTrusted",
  "sandboxPolicy": {
    "type": "workspaceWrite",
    "writableRoots": ["/Users/me/project"],
    "networkAccess": true
  },
  "model": "gpt-5.1-codex",
  "effort": "medium",
  "summary": "concise",
  "personality": "friendly",
  "outputSchema": {
    "type": "object",
    "properties": { "answer": { "type": "string" } },
    "required": ["answer"],
    "additionalProperties": false
  }
} }
{ "id": 30, "result": { "turn": { "id": "turn_456", "status": "inProgress", "items": [], "error": null } } }

Steer an active turn

Use turn/steer to append more user input to the active in-flight turn.

Include expectedTurnId; it must match the active turn id.
The request fails if there is no active turn on the thread.
turn/steer doesn’t emit a new turn/started notification.
turn/steer doesn’t accept turn-level overrides (model, cwd, sandboxPolicy, or outputSchema).

{ "method": "turn/steer", "id": 32, "params": {
  "threadId": "thr_123",
  "input": [ { "type": "text", "text": "Actually focus on failing tests first." } ],
  "expectedTurnId": "turn_456"
} }
{ "id": 32, "result": { "turnId": "turn_456" } }

Start a turn (invoke a skill)

Invoke a skill explicitly by including $<skill-name> in the text input and adding a skill input item alongside it.

{ "method": "turn/start", "id": 33, "params": {
  "threadId": "thr_123",
  "input": [
    { "type": "text", "text": "$skill-creator Add a new skill for triaging flaky CI and include step-by-step usage." },
    { "type": "skill", "name": "skill-creator", "path": "/Users/me/.codex/skills/skill-creator/SKILL.md" }
  ]
} }
{ "id": 33, "result": { "turn": { "id": "turn_457", "status": "inProgress", "items": [], "error": null } } }

Interrupt a turn

{ "method": "turn/interrupt", "id": 31, "params": { "threadId": "thr_123", "turnId": "turn_456" } }
{ "id": 31, "result": {} }

On success, the turn finishes with status: "interrupted".

Review

review/start runs the Codex reviewer for a thread and streams review items. Targets include:

uncommittedChanges
baseBranch (diff against a branch)
commit (review a specific commit)
custom (free-form instructions)

Use delivery: "inline" (default) to run the review on the existing thread, or delivery: "detached" to fork a new review thread.

Example request/response:

{ "method": "review/start", "id": 40, "params": {
  "threadId": "thr_123",
  "delivery": "inline",
  "target": { "type": "commit", "sha": "1234567deadbeef", "title": "Polish tui colors" }
} }
{ "id": 40, "result": {
  "turn": {
    "id": "turn_900",
    "status": "inProgress",
    "items": [
      { "type": "userMessage", "id": "turn_900", "content": [ { "type": "text", "text": "Review commit 1234567: Polish tui colors" } ] }
    ],
    "error": null
  },
  "reviewThreadId": "thr_123"
} }

For a detached review, use "delivery": "detached". The response is the same shape, but reviewThreadId will be the id of the new review thread (different from the original threadId). The server also emits a thread/started notification for that new thread before streaming the review turn.

Codex streams the usual turn/started notification followed by an item/started with an enteredReviewMode item:

{
  "method": "item/started",
  "params": {
    "item": {
      "type": "enteredReviewMode",
      "id": "turn_900",
      "review": "current changes"
    }
  }
}

When the reviewer finishes, the server emits item/started and item/completed containing an exitedReviewMode item with the final review text:

{
  "method": "item/completed",
  "params": {
    "item": {
      "type": "exitedReviewMode",
      "id": "turn_900",
      "review": "Looks solid overall..."
    }
  }
}

Use this notification to render the reviewer output in your client.

Command execution

command/exec runs a single command (argv array) under the server sandbox without creating a thread.

{ "method": "command/exec", "id": 50, "params": {
  "command": ["ls", "-la"],
  "cwd": "/Users/me/project",
  "sandboxPolicy": { "type": "workspaceWrite" },
  "timeoutMs": 10000
} }
{ "id": 50, "result": { "exitCode": 0, "stdout": "...", "stderr": "" } }

Use sandboxPolicy.type = "externalSandbox" if you already sandbox the server process and want Codex to skip its own sandbox enforcement. For external sandbox mode, set networkAccess to restricted (default) or enabled. For readOnly and workspaceWrite, use the same optional access / readOnlyAccess structure shown above.

Notes:

The server rejects empty command arrays.
sandboxPolicy accepts the same shape used by turn/start (for example, dangerFullAccess, readOnly, workspaceWrite, externalSandbox).
When omitted, timeoutMs falls back to the server default.

Events

Event notifications are the server-initiated stream for thread lifecycles, turn lifecycles, and the items within them. After you start or resume a thread, keep reading the active transport stream for thread/started, turn/*, and item/* notifications.

Notification opt-out

Clients can suppress specific notifications per connection by sending exact method names in initialize.params.capabilities.optOutNotificationMethods.

Exact-match only: item/agentMessage/delta suppresses only that method.
Unknown method names are ignored.
Applies to both legacy (codex/event/*) and v2 (thread/*, turn/*, item/*, etc.) notifications.
Doesn’t apply to requests, responses, or errors.

Fuzzy file search events (experimental)

The fuzzy file search session API emits per-query notifications:

fuzzyFileSearch/sessionUpdated - { sessionId, query, files } with the current matches for the active query.
fuzzyFileSearch/sessionCompleted - { sessionId } once indexing and matching for that query completes.

Turn events

turn/started - { turn } with the turn id, empty items, and status: "inProgress".
turn/completed - { turn } where turn.status is completed, interrupted, or failed; failures carry { error: { message, codexErrorInfo?, additionalDetails? } }.
turn/diff/updated - { threadId, turnId, diff } with the latest aggregated unified diff across every file change in the turn.
turn/plan/updated - { turnId, explanation?, plan } whenever the agent shares or changes its plan; each plan entry is { step, status } with status in pending, inProgress, or completed.
thread/tokenUsage/updated - usage updates for the active thread.

turn/diff/updated and turn/plan/updated currently include empty items arrays even when item events stream. Use item/* notifications as the source of truth for turn items.

Items

ThreadItem is the tagged union carried in turn responses and item/* notifications. Common item types include:

userMessage - {id, content} where content is a list of user inputs (text, image, or localImage).
agentMessage - {id, text} containing the accumulated agent reply.
plan - {id, text} containing proposed plan text in plan mode. Treat the final plan item from item/completed as authoritative.
reasoning - {id, summary, content} where summary holds streamed reasoning summaries and content holds raw reasoning blocks.
commandExecution - {id, command, cwd, status, commandActions, aggregatedOutput?, exitCode?, durationMs?}.
fileChange - {id, changes, status} describing proposed edits; changes list {path, kind, diff}.
mcpToolCall - {id, server, tool, status, arguments, result?, error?}.
collabToolCall - {id, tool, status, senderThreadId, receiverThreadId?, newThreadId?, prompt?, agentStatus?}.
webSearch - {id, query, action?} for web search requests issued by the agent.
imageView - {id, path} emitted when the agent invokes the image viewer tool.
enteredReviewMode - {id, review} sent when the reviewer starts.
exitedReviewMode - {id, review} emitted when the reviewer finishes.
contextCompaction - {id} emitted when Codex compacts the conversation history.

For webSearch.action, the action type can be search (query?, queries?), openPage (url?), or findInPage (url?, pattern?).

The app server deprecates the legacy thread/compacted notification; use the contextCompaction item instead.

All items emit two shared lifecycle events:

item/started - emits the full item when a new unit of work begins; the item.id matches the itemId used by deltas.
item/completed - sends the final item once work finishes; treat this as the authoritative state.

Item deltas

item/agentMessage/delta - appends streamed text for the agent message.
item/plan/delta - streams proposed plan text. The final plan item may not exactly equal the concatenated deltas.
item/reasoning/summaryTextDelta - streams readable reasoning summaries; summaryIndex increments when a new summary section opens.
item/reasoning/summaryPartAdded - marks a boundary between reasoning summary sections.
item/reasoning/textDelta - streams raw reasoning text (when supported by the model).
item/commandExecution/outputDelta - streams stdout/stderr for a command; append deltas in order.
item/fileChange/outputDelta - contains the tool call response of the underlying apply_patch tool call.

Errors

If a turn fails, the server emits an error event with { error: { message, codexErrorInfo?, additionalDetails? } } and then finishes the turn with status: "failed". When an upstream HTTP status is available, it appears in codexErrorInfo.httpStatusCode.

Common codexErrorInfo values include:

ContextWindowExceeded
UsageLimitExceeded
HttpConnectionFailed (4xx/5xx upstream errors)
ResponseStreamConnectionFailed
ResponseStreamDisconnected
ResponseTooManyFailedAttempts
BadRequest, Unauthorized, SandboxError, InternalServerError, Other

When an upstream HTTP status is available, the server forwards it in httpStatusCode on the relevant codexErrorInfo variant.

Approvals

Depending on a user’s Codex settings, command execution and file changes may require approval. The app-server sends a server-initiated JSON-RPC request to the client, and the client responds with a decision payload.

Command execution decisions: accept, acceptForSession, decline, cancel, or { "acceptWithExecpolicyAmendment": { "execpolicy_amendment": ["cmd", "..."] } }.
File change decisions: accept, acceptForSession, decline, cancel.
Requests include threadId and turnId - use them to scope UI state to the active conversation.
The server resumes or declines the work and ends the item with item/completed.

Command execution approvals

Order of messages:

item/started shows the pending commandExecution item with command, cwd, and other fields.
item/commandExecution/requestApproval includes itemId, threadId, turnId, optional reason, optional command, optional cwd, optional commandActions, and optional proposedExecpolicyAmendment.
Client responds with one of the command execution approval decisions above.
item/completed returns the final commandExecution item with status: completed | failed | declined.

File change approvals

Order of messages:

item/started emits a fileChange item with proposed changes and status: "inProgress".
item/fileChange/requestApproval includes itemId, threadId, turnId, optional reason, and optional grantRoot.
Client responds with one of the file change approval decisions above.
item/completed returns the final fileChange item with status: completed | failed | declined.

MCP tool-call approvals (apps)

App (connector) tool calls can also require approval. When an app tool call has side effects, the server may elicit approval with tool/requestUserInput and options such as Accept, Decline, and Cancel. If the user declines or cancels, the related mcpToolCall item completes with an error instead of running the tool.

Skills

Invoke a skill by including $<skill-name> in the user text input. Add a skill input item (recommended) so the server injects full skill instructions instead of relying on the model to resolve the name.

{
  "method": "turn/start",
  "id": 101,
  "params": {
    "threadId": "thread-1",
    "input": [
      {
        "type": "text",
        "text": "$skill-creator Add a new skill for triaging flaky CI."
      },
      {
        "type": "skill",
        "name": "skill-creator",
        "path": "/Users/me/.codex/skills/skill-creator/SKILL.md"
      }
    ]
  }
}

If you omit the skill item, the model will still parse the $<skill-name> marker and try to locate the skill, which can add latency.

Example:

$skill-creator Add a new skill for triaging flaky CI and include step-by-step usage.

Use skills/list to fetch available skills (optionally scoped by cwds, with forceReload). You can also include perCwdExtraUserRoots to scan extra absolute paths as user scope for specific cwd values. App-server ignores entries whose cwd isn’t present in cwds. skills/list may reuse a cached result per cwd; set forceReload: true to refresh from disk. When present, the server reads interface and dependencies from SKILL.json.

{ "method": "skills/list", "id": 25, "params": {
  "cwds": ["/Users/me/project", "/Users/me/other-project"],
  "forceReload": true,
  "perCwdExtraUserRoots": [
    {
      "cwd": "/Users/me/project",
      "extraUserRoots": ["/Users/me/shared-skills"]
    }
  ]
} }
{ "id": 25, "result": {
  "data": [{
    "cwd": "/Users/me/project",
    "skills": [
      {
        "name": "skill-creator",
        "description": "Create or update a Codex skill",
        "enabled": true,
        "interface": {
          "displayName": "Skill Creator",
          "shortDescription": "Create or update a Codex skill"
        },
        "dependencies": {
          "tools": [
            {
              "type": "env_var",
              "value": "GITHUB_TOKEN",
              "description": "GitHub API token"
            },
            {
              "type": "mcp",
              "value": "github",
              "transport": "streamable_http",
              "url": "https://example.com/mcp"
            }
          ]
        }
      }
    ],
    "errors": []
  }]
} }

To enable or disable a skill by path:

{
  "method": "skills/config/write",
  "id": 26,
  "params": {
    "path": "/Users/me/.codex/skills/skill-creator/SKILL.md",
    "enabled": false
  }
}

Apps (connectors)

Use app/list to fetch available apps. In the CLI/TUI, /apps is the user-facing picker; in custom clients, call app/list directly. Each entry includes both isAccessible (available to the user) and isEnabled (enabled in config.toml) so clients can distinguish install/access from local enabled state.

{ "method": "app/list", "id": 50, "params": {
  "cursor": null,
  "limit": 50,
  "threadId": "thread-1",
  "forceRefetch": false
} }
{ "id": 50, "result": {
  "data": [
    {
      "id": "demo-app",
      "name": "Demo App",
      "description": "Example connector for documentation.",
      "logoUrl": "https://example.com/demo-app.png",
      "installUrl": "https://chatgpt.com/apps/demo-app/demo-app",
      "isAccessible": true,
      "isEnabled": true
    }
  ],
  "nextCursor": null
} }

If you provide threadId, app feature gating (features.apps) uses that thread’s config snapshot. When omitted, app-server uses the latest global config.

app/list returns after both accessible apps and directory apps load. Set forceRefetch: true to bypass app caches and fetch fresh data. Cache entries are only replaced when refreshes succeed.

The server also emits app/list/updated notifications whenever either source (accessible apps or directory apps) finishes loading. Each notification includes the latest merged app list.

{
  "method": "app/list/updated",
  "params": {
    "data": [
      {
        "id": "demo-app",
        "name": "Demo App",
        "description": "Example connector for documentation.",
        "logoUrl": "https://example.com/demo-app.png",
        "installUrl": "https://chatgpt.com/apps/demo-app/demo-app",
        "isAccessible": true,
        "isEnabled": true
      }
    ]
  }
}

Invoke an app by inserting $<app-slug> in the text input and adding a mention input item with the app://<id> path (recommended).

{
  "method": "turn/start",
  "id": 51,
  "params": {
    "threadId": "thread-1",
    "input": [
      {
        "type": "text",
        "text": "$demo-app Pull the latest updates from the team."
      },
      {
        "type": "mention",
        "name": "Demo App",
        "path": "app://demo-app"
      }
    ]
  }
}

Auth endpoints

The JSON-RPC auth/account surface exposes request/response methods plus server-initiated notifications (no id). Use these to determine auth state, start or cancel logins, logout, and inspect ChatGPT rate limits.

Authentication modes

Codex supports three authentication modes. account/updated.authMode shows the active mode, and account/read also reports it.

API key (apikey) - the caller supplies an OpenAI API key and Codex stores it for API requests.
ChatGPT managed (chatgpt) - Codex owns the ChatGPT OAuth flow, persists tokens, and refreshes them automatically.
ChatGPT external tokens (chatgptAuthTokens) - a host app supplies idToken and accessToken directly. Codex stores these tokens in memory, and the host app must refresh them when asked.

API overview

account/read - fetch current account info; optionally refresh tokens.
account/login/start - begin login (apiKey, chatgpt, or chatgptAuthTokens).
account/login/completed (notify) - emitted when a login attempt finishes (success or error).
account/login/cancel - cancel a pending ChatGPT login by loginId.
account/logout - sign out; triggers account/updated.
account/updated (notify) - emitted whenever auth mode changes (authMode: apikey, chatgpt, chatgptAuthTokens, or null).
account/chatgptAuthTokens/refresh (server request) - request fresh externally managed ChatGPT tokens after an authorization error.
account/rateLimits/read - fetch ChatGPT rate limits.
account/rateLimits/updated (notify) - emitted whenever a user’s ChatGPT rate limits change.
mcpServer/oauthLogin/completed (notify) - emitted after a mcpServer/oauth/login flow finishes; payload includes { name, success, error? }.

1) Check auth state

Request:

{ "method": "account/read", "id": 1, "params": { "refreshToken": false } }

Response examples:

{ "id": 1, "result": { "account": null, "requiresOpenaiAuth": false } }

{ "id": 1, "result": { "account": null, "requiresOpenaiAuth": true } }

{
  "id": 1,
  "result": { "account": { "type": "apiKey" }, "requiresOpenaiAuth": true }
}

{
  "id": 1,
  "result": {
    "account": {
      "type": "chatgpt",
      "email": "user@example.com",
      "planType": "pro"
    },
    "requiresOpenaiAuth": true
  }
}

Field notes:

refreshToken (boolean): set true to force a token refresh in managed ChatGPT mode. In external token mode (chatgptAuthTokens), app-server ignores this flag.
requiresOpenaiAuth reflects the active provider; when false, Codex can run without OpenAI credentials.

2) Log in with an API key

Send:

{
  "method": "account/login/start",
  "id": 2,
  "params": { "type": "apiKey", "apiKey": "sk-..." }
}

Expect:

{ "id": 2, "result": { "type": "apiKey" } }

Notifications:

{
  "method": "account/login/completed",
  "params": { "loginId": null, "success": true, "error": null }
}

{ "method": "account/updated", "params": { "authMode": "apikey" } }

3) Log in with ChatGPT (browser flow)

Start:

{ "method": "account/login/start", "id": 3, "params": { "type": "chatgpt" } }

{
  "id": 3,
  "result": {
    "type": "chatgpt",
    "loginId": "<uuid>",
    "authUrl": "https://chatgpt.com/...&redirect_uri=http%3A%2F%2Flocalhost%3A<port>%2Fauth%2Fcallback"
  }
}

Open authUrl in a browser; the app-server hosts the local callback.

Wait for notifications:

{
  "method": "account/login/completed",
  "params": { "loginId": "<uuid>", "success": true, "error": null }
}

{ "method": "account/updated", "params": { "authMode": "chatgpt" } }

3b) Log in with externally managed ChatGPT tokens (`chatgptAuthTokens`)

Use this mode when a host application owns the user’s ChatGPT auth lifecycle and supplies tokens directly.

Send:

{
  "method": "account/login/start",
  "id": 7,
  "params": {
    "type": "chatgptAuthTokens",
    "idToken": "<jwt>",
    "accessToken": "<jwt>"
  }
}

Expect:

{ "id": 7, "result": { "type": "chatgptAuthTokens" } }

Notifications:

{
  "method": "account/login/completed",
  "params": { "loginId": null, "success": true, "error": null }
}

{
  "method": "account/updated",
  "params": { "authMode": "chatgptAuthTokens" }
}

When the server receives a 401 Unauthorized, it may request refreshed tokens from the host app:

{
  "method": "account/chatgptAuthTokens/refresh",
  "id": 8,
  "params": { "reason": "unauthorized", "previousAccountId": "org-123" }
}
{ "id": 8, "result": { "idToken": "<jwt>", "accessToken": "<jwt>" } }

The server retries the original request after a successful refresh response. Requests time out after about 10 seconds.

{ "method": "account/login/cancel", "id": 4, "params": { "loginId": "<uuid>" } }
{ "method": "account/login/completed", "params": { "loginId": "<uuid>", "success": false, "error": "..." } }

5) Logout

{ "method": "account/logout", "id": 5 }
{ "id": 5, "result": {} }
{ "method": "account/updated", "params": { "authMode": null } }

6) Rate limits (ChatGPT)

{ "method": "account/rateLimits/read", "id": 6 }
{ "id": 6, "result": {
  "rateLimits": {
    "limitId": "codex",
    "limitName": null,
    "primary": { "usedPercent": 25, "windowDurationMins": 15, "resetsAt": 1730947200 },
    "secondary": null
  },
  "rateLimitsByLimitId": {
    "codex": {
      "limitId": "codex",
      "limitName": null,
      "primary": { "usedPercent": 25, "windowDurationMins": 15, "resetsAt": 1730947200 },
      "secondary": null
    },
    "codex_other": {
      "limitId": "codex_other",
      "limitName": "codex_other",
      "primary": { "usedPercent": 42, "windowDurationMins": 60, "resetsAt": 1730950800 },
      "secondary": null
    }
  }
} }
{ "method": "account/rateLimits/updated", "params": {
  "rateLimits": {
    "limitId": "codex",
    "primary": { "usedPercent": 31, "windowDurationMins": 15, "resetsAt": 1730948100 }
  }
} }

Field notes:

rateLimits is the backward-compatible single-bucket view.
rateLimitsByLimitId (when present) is the multi-bucket view keyed by metered limit_id (for example codex).
limitId is the metered bucket identifier.
limitName is an optional user-facing label for the bucket.
usedPercent is current usage within the quota window.
windowDurationMins is the quota window length.
resetsAt is a Unix timestamp (seconds) for the next reset.

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MCP tool-call approvals (apps)

Skills

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Auth endpoints

Authentication modes

API overview

1) Check auth state

2) Log in with an API key

List models (`model/list`)

List experimental features (`experimentalFeature/list`)

Sandbox read access (`ReadOnlyAccess`)

3b) Log in with externally managed ChatGPT tokens (`chatgptAuthTokens`)