OpenAI Codex Provider

Setup

Appam's Codex provider uses ChatGPT OAuth credentials against the Codex backend. You can either provide a bearer token explicitly or let Appam read and refresh credentials from its local auth cache.

export OPENAI_CODEX_MODEL="gpt-5.4"                    # optional
export OPENAI_CODEX_ACCESS_TOKEN="eyJ..."              # optional explicit token
export OPENAI_CODEX_AUTH_FILE="$HOME/.appam/auth.json" # optional auth cache override

If OPENAI_CODEX_ACCESS_TOKEN is unset, Appam looks for an openai-codex OAuth entry in OPENAI_CODEX_AUTH_FILE and refreshes it before expiry.

Construction

Agent::quick() auto-detects the provider from openai-codex/... model strings:

use appam::prelude::*;

let agent = Agent::quick(
    "openai-codex/gpt-5.4",
    "You are a helpful coding assistant.",
    vec![],
)?;

For explicit configuration, use LlmProvider::OpenAICodex:

use appam::prelude::*;

let agent = AgentBuilder::new("codex-agent")
    .provider(LlmProvider::OpenAICodex)
    .model("gpt-5.4")
    .system_prompt("You are a helpful coding assistant.")
    .build()?;

Authentication

The Codex provider resolves auth in this order:

1. OpenAICodexConfig.access_token
2. OPENAI_CODEX_ACCESS_TOKEN
3. cached OAuth credentials in OPENAI_CODEX_AUTH_FILE

For trusted local CLI workflows, use the example binary to trigger the browser login flow and persist credentials to ~/.appam/auth.json.

Reasoning

The provider reuses Appam's OpenAI reasoning and text verbosity controls:

use appam::prelude::*;

let agent = AgentBuilder::new("codex-reasoning")
    .provider(LlmProvider::OpenAICodex)
    .model("gpt-5.4")
    .system_prompt("You are a reasoning assistant.")
    .openai_reasoning(ReasoningConfig::high_effort())
    .build()?;

Example Binary

cargo run --example coding-agent-openai-codex

The example will try cached auth first and fall back to an interactive ChatGPT login flow only when no usable Codex credential is available.