Codex

Codex builds its own request body, so the deadline goes on an agent key.

Set this up with an agent

Copy the block below into any coding agent. It never asks for your API key: you run the one export line yourself.

Copy agent setup prompt

Configure the Codex CLI to send its requests to FlexInference. Do not change my existing Codex setup: create a separate profile I opt into per run.

You will never see or handle my API key. The profile stores only the NAME of an environment variable, and I export the value myself. Do not ask me for the key, and do not read it from my environment.

1. Create `~/.codex/flexinference.config.toml` with exactly this content:

model = "gpt-5.6-sol"
model_provider = "flexinference"

[model_providers.flexinference]
name = "FlexInference"
base_url = "https://api.flexinference.com/v1"
wire_api = "responses"
env_key = "FLEX_API_KEY"

2. Tell me to export the key myself, in the shell I will run Codex from:

   export FLEX_API_KEY=<paste your key here>

   Print that line for me to run. Do not run it, do not ask for the value, and do not add it to my shell profile.

3. Tell me to start Codex with `codex --profile flexinference`.

Rules that matter, do not deviate:
- Keep the `model` line. Codex defaults to a slug ending in `-codex`, which FlexInference recognizes but holds no price for and never races. Use the full `gpt-5.6-sol`; the bare `gpt-5.6` alias makes Codex print a metadata warning.
- Keep `wire_api = "responses"`. FlexInference serves that surface at `/v1/responses`.
- Never add `service_tier`. FlexInference derives the tier from the key's deadline and returns `400 service_tier_not_allowed` if the request carries its own.
- `env_key` and `auth` are mutually exclusive. Use `env_key` unless I ask for a keychain helper.
- Do not set `request_max_retries`. My key may carry its own retry policy and the two stack.

Verify by checking the file parses under `codex --profile flexinference --strict-config`, then report what you changed.

Configure Codex

Codex keeps each profile in its own file. This profile leaves your usual Codex setup alone, and you opt in per run with --profile.

Write the profile file. Paste this once:

mkdir -p ~/.codex && cat > ~/.codex/flexinference.config.toml <<'EOF'
model = "gpt-5.6-sol"
model_provider = "flexinference"

[model_providers.flexinference]
name = "FlexInference"
base_url = "https://api.flexinference.com/v1"
wire_api = "responses"
env_key = "FLEX_API_KEY"
EOF

Export the key Codex reads. The profile file never holds it.

export FLEX_API_KEY=flex_live_...

Start Codex with the profile.

codex --profile flexinference

That is the whole integration. Codex calls /v1/responses, sends the key as a bearer token, and the key supplies the deadline. The session header names the provider in use, so you can see the profile took. To reach us on every Codex run instead, put the same lines in ~/.codex/config.toml. The top-level model and model_provider there set your default. env_key and auth rule each other out. env_key reads the key from your environment, which is the short path. Keep secrets in a keychain instead and you leave env_key out, then name a helper command in auth. Keep the model line. Codex otherwise defaults to a slug ending in -codex, which we hold no price for and never race. Use the full gpt-5.6-sol, because the bare gpt-5.6 alias makes Codex print a metadata warning.

Troubleshooting

Nothing reaches us at all. You ran a plain codex, which uses your usual provider and account. Start it with --profile flexinference. Any error you saw is theirs, usage limits included, and the session header names the provider in use. 400 model_not_priced_for_managed. model is unset, so the request arrived on a -codex slug we hold no price for. Set model = "gpt-5.6-sol" in the profile. On your own provider key we run that slug instead, with no cost figure of ours. 400 service_tier_not_allowed. The profile sets service_tier, and we read the tier from the deadline instead. Remove the line. Anything not specific to Codex is on agent keys.

Get started

Concepts

Additional Features

Using the API

Agent Keys + Integrations

Set this up with an agent

Configure Codex

Troubleshooting

​Set this up with an agent

​Configure Codex

​Troubleshooting

Set this up with an agent

Configure Codex

Troubleshooting