Stop Guessing Which AI Model to Use: Test One Codex Task through RelayRouter

Recent AI model releases make one question more important than “Which name is newest?” OpenAI released GPT-6.1 Terra on October 26 for visual reasoning, precise computer use and clear writing. Anthropic introduced Claude Haiku 5.5 on October 7 for fast, high-volume work. Google made Gemini 4 Argon broadly available in October for complex, long-horizon workflows. These releases serve different jobs. None of those announcements proves that a particular model route is available or Codex-compatible in your RelayRouter account.

That is why today's practical exercise keeps the task fixed. We will connect Codex through RelayRouter, ask it to build a small support-ticket triage tool, and use the same CSV and tests whenever we evaluate another compatible route.

What RelayRouter makes convenient

Codex works in your project folder. RelayRouter is the model connection you configure. The model helps Codex understand the request and complete the coding work. Keeping the connection in one user-level provider block gives you one place to identify the API address, credential variable and selected model ID.

The registration link is for your browser. It is not the API address. The supplied setup screenshot uses https://api.relayrouter.ai/v1, but your current account console is the authority. Copy the API Base URL, API key and exact model ID from there. Select a token group intended for Codex if your console offers one.

Install Codex

Install a current Node.js LTS version first. Then open PowerShell on Windows or Terminal on macOS/Linux:

npm install -g @openai/codex
codex --version

Keep the version number. Codex CLI 0.166.0, released on October 29, added codex doctor --network-only for focused connectivity and WebSocket diagnostics. This is useful when a custom route fails, but diagnostics do not replace the final file-and-test check.

Add a small provider definition

Open your user configuration: %USERPROFILE%/.codex/config.toml on Windows, or ~/.codex/config.toml on macOS/Linux. Back up an existing file, keep unrelated settings, and merge the provider only once.

Save at USER LEVEL as ~/.codex/config.toml after backing up existing settings.
Replace the model ID and confirm the API Base URL in your current RelayRouter console.
model_provider = "relayrouter"
model = "REPLACE_WITH_CODEX_COMPATIBLE_MODEL_ID"

[model_providers.relayrouter]
name = "RelayRouter"
base_url = "https://api.relayrouter.ai/v1"
wire_api = "responses"
env_key = "RELAYROUTER_API_KEY"
requires_openai_auth = false

The current Codex reference supports base_url, env_key and wire_api inside a custom provider. Responses is the supported protocol. A route that only supports ordinary chat is not enough for Codex tool work.

Give the current terminal the API key

Windows PowerShell:

$secret = Read-Host "RelayRouter API key" -AsSecureString
$ptr = Runtime.InteropServices.Marshal::SecureStringToBSTR($secret)
try {
$env:RELAYROUTER_API_KEY = Runtime.InteropServices.Marshal::PtrToStringBSTR($ptr)
} finally {

}
[bool]$env:RELAYROUTER_API_KEY

macOS/Linux:

printf 'RelayRouter API key: '
IFS= read -r -s RELAYROUTER_API_KEY
printf '\n'
export RELAYROUTER_API_KEY
[ -n "$RELAYROUTER_API_KEY" ] && printf 'Key is set\n'

Start Codex from that same terminal. The key stays local to the shell and its child processes in this example.

Use a task with a known answer

Save this as support_tickets.csv:

ticket_id,subject,message
T001,Billing question,Invoice shows two charges for the same month
T002,Login problem,Reset link opens but the new password is rejected
T003,Feature request,Please add a dark mode for the dashboard
T004,Billing question,Need a VAT invoice for the last payment
T005,Login problem,Two factor code never arrives
T006,Feature request,Can exports include the assigned owner

The subject column already tells us the correct category. There are two billing tickets, two access tickets and two product requests. That makes the fixture useful for checking whether the generated tool followed the rule.

Open the folder, run codex, and paste this task:

Create triage_tickets.py using only the Python standard library. Read support_tickets.csv with csv.DictReader. Do not modify the CSV. Classify each row using exact subject rules: Billing question -> billing, Login problem -> access, Feature request -> product. Reject unknown subjects and missing required columns with a clear ValueError. Write triage_summary.json beside the chosen CSV with category_counts in the order billing, access, product, and tickets as a list containing ticket_id and category. Accept an optional CSV path argument. For the provided fixture the expected category_counts are billing=2, access=2, product=2. Add unittest cases for the fixture, an unknown subject, missing columns, and an empty valid file. Run python -m unittest -v and report actual results.

The task asks for deterministic rules, not an open-ended classifier. That matters: when you compare routes, a model cannot improve its score by inventing a different taxonomy.

Inspect the deliverable

The expected counts are:

{"billing": 2, "access": 2, "product": 2}

Run the generated script and tests. Open triage_summary.json. Confirm the original CSV is unchanged. The downloadable kit also includes an independently written reference solution, so you can understand the expected behavior before spending time on a live route.

Compare a second compatible route

Change only the model ID to another route that your RelayRouter console says is compatible with Codex and Responses. Keep the CSV, task and tests unchanged. Record:

• Did Codex create the requested files?
• Did all tests pass?
• Did it preserve the input?
• How many corrections did you make?
• How long did a reviewer need to understand the result?

Do not treat a shorter answer as automatically better. Do not treat a model launch announcement as gateway availability. The useful route is the one that completes your actual task reliably under the conditions you care about.

Troubleshoot one layer at a time

A missing codex command points to installation or PATH. A missing environment variable points to the launching shell. A 401 or 403 points toward key validity or permissions. A 404 or model-not-found response calls for checking the Base URL, model ID, token group and Responses route together. A 429 points toward the stated rate or quota limit.

On a compatible version, inspect codex doctor --help and then try codex doctor --network-only. Finally, run the local task again. Connectivity, authentication and successful tool work are three different checks.

Start with one repeatable test: https://relayrouter.app/register?aff=xc9N

Disclosure: this post promotes RelayRouter; the registration URL is a referral link.

Sources

Codex release notes ({CODEX_NEWS}) · OpenAI model changelog ({OPENAI_NEWS}) · Codex configuration reference ({CODEX_CONFIG}) · Claude Haiku 5.5 ({ANTHROPIC}) · Gemini 4 Argon ({GEMINI})