Codex setup

Prerequisites: Environment check, API key.

Codex uses https://apimaster.ai/v1 (OpenAI-compatible).

---

Windows

Win + R → %userprofile%\.codex

Create if missing:

config.toml

disable_response_storage = true
model = "gpt-5.4"
model_provider = "apimaster"
model_reasoning_effort = "high"
model_verbosity = "high"

[features]
web_search_request = true

[model_providers.apimaster]
base_url = "https://apimaster.ai/v1"
name = "apimaster"
requires_openai_auth = true
wire_api = "responses"

auth.json

{
  "OPENAI_API_KEY": "YOUR_API_KEY"
}

Test: codex

---

macOS

~/.codex — same files; macOS config.toml example:

model_provider = "apimaster"
model = "gpt-5.4"
model_reasoning_effort = "high"
network_access = "enabled"
disable_response_storage = true
model_verbosity = "high"

[model_providers.apimaster]
name = "apimaster"
base_url = "https://apimaster.ai/v1"
wire_api = "responses"
requires_openai_auth = true

auth.json as above. Test: codex

---

Notes

• Set model to gpt-5.5 etc. per Supported models.
• If wire_api = "responses" fails on your Codex version, try wire_api = "chat" or remove the line.

Issue	Fix
401	auth.json key
404	Model id + account access
Timeout	base_url must be exactly https://apimaster.ai/v1