Codex

fusionkit codex launches the OpenAI Codex CLI with the fused panel as its model backend. Codex speaks the OpenAI Responses dialect to the local gateway and treats fusion-panel as a normal model.

cd your-git-repo
fusionkit codex

Anything after the tool name is forwarded to Codex, so your usual Codex arguments still work:

fusionkit codex -- "fix the failing parser test"

Prerequisites

• The codex binary on your PATH. Install it from github.com/openai/codex.
• A valid .fusionkit/fusion.json v4 file and RouteKit endpoint config. Provider credentials are referenced only by .routekit/router.yaml.

fusionkit doctor verifies both before you launch.

How the wiring works

The launcher never touches your own Codex configuration. It creates a temporary CODEX_HOME for the session and writes a config.toml that registers the gateway as a Responses provider:

model = "fusion-panel"
model_provider = "fusionkit-local"

[model_providers.fusionkit-local]
name = "FusionKit local"
base_url = "http://127.0.0.1:<port>/v1"
wire_api = "responses"
requires_openai_auth = false

Codex is then spawned with CODEX_HOME pointing at that directory, and the directory is deleted when the session ends. Your ~/.codex/config.toml stays as it was.

If you prefer to wire Codex by hand against a running fusionkit serve, the same snippet is printed at boot; paste it into your own ~/.codex/config.toml or a temporary CODEX_HOME.

The model picker

Codex's /model picker lists the default fusion-panel model and every other named ensemble (fusion-<name>). RouteKit owns single-model endpoint launches.

Each model also gets a [profiles.*] entry, so you can start Codex on a different ensemble directly:

fusionkit codex -- --profile fusion-deep

Sub-agents

By default the launcher defines one Codex agent role per named ensemble, so spawn_agent can delegate a task to any ensemble out of the box. Delegation depth is capped at one level, because a fused sub-agent is itself a whole panel run. Pass --no-subagents (or set "subagents": false in .fusionkit/fusion.json) to skip this.

Caveats

• Codex validates its model catalog and agent-role config at startup, and the catalog schema changes between Codex releases. If Codex exits within the first two seconds, FusionKit retries automatically: first without the model catalog, then without the sub-agent roles. Fusion keeps working in both fallbacks; you lose only picker niceties.
• Direct and single-model mode belongs to RouteKit; FusionKit has no --direct.

Related pages

• Codex subscription disclosure for credential ownership, billing, quota failover, protocol limits, and qualification status.
• Quickstart for the first session.
• Command reference for every launch flag.
• Rate-limit handoff for passthrough failover.