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Setting up T3 Code

T3 Code keeps a separate Nexus entry for each coding agent. Codex and Claude Code use different protocols and base URLs, so they stay in two profiles.

The shared order is on Client setup.

Values

Profile Base URL Protocol Route
Codex https://api.nexus-hub.tech/v1 OpenAI Responses POST /v1/responses
Claude Code https://api.nexus-hub.tech Anthropic Messages POST /v1/messages

Codex profile

  1. Open T3 Code settings and add a Codex profile.
  2. Select a custom endpoint.
  3. Set the base URL to https://api.nexus-hub.tech/v1.
  4. Enter the Nexus API key in the API key field. Do not add Bearer or spaces.
  5. Select the Responses protocol.
  6. Select a model returned by GET /v1/models.

The same profile file as the CLI, without the key:

model = "MODEL_FROM_V1_MODELS"
model_provider = "nexus"

[model_providers.nexus]
name = "Nexus"
base_url = "https://api.nexus-hub.tech/v1"
env_key = "NEXUS_API_KEY"
wire_api = "responses"

Set NEXUS_API_KEY in the environment. Do not change wire_api away from responses. Context window fields are in Setting up Codex.

Claude Code profile

  1. Add a separate Claude Code profile.
  2. Set ANTHROPIC_BASE_URL to https://api.nexus-hub.tech, with no /v1.
  3. Set either ANTHROPIC_AUTH_TOKEN or ANTHROPIC_API_KEY to the Nexus key. Use one variable.
  4. Select a model from GET /v1/models.

Details of the Claude Code environment are in Setting up Claude Code.

Check

Restart the coding-agent session after you switch the active profile. Send a short message. A normal reply means that profile works.

If it does not work

  • 401 or invalid_key: the key field or the environment variable for the active profile is empty or has extra spaces.
  • model_not_found or model_not_allowed: the id is not in GET /v1/models for this key.
  • unsupported_model: the Codex profile is not on Responses, or the Claude profile is using an id that Messages does not allow.
  • 404: Codex uses the /v1 base. Claude Code uses the base without /v1.

Send support the route, error code, time, and x-request-id. Do not send the key or a full prompt.

Official references: Codex config reference and Connect Claude Code to an LLM gateway.