Summary
The Codex multi-agent sub-agent launcher rejects gpt-5.6-luna as an unknown model even though Luna is configured for the Builder role and a direct Codex Luna Max run succeeds on the same machine and ChatGPT account.
Environment
- macOS 26.5.1, arm64
- Codex desktop-bundled CLI:
0.147.0-alpha.6.5
- Authentication: ChatGPT
- Global config:
model = "gpt-5.6-luna", model_reasoning_effort = "max"
- Global and project Builder definitions:
model = "gpt-5.6-luna", model_reasoning_effort = "max"
- Project sub-agent defaults also request Luna Max
- Desktop app has been restarted several times without changing behavior
Reproduction
- From a GPT-5.6 task, create a sub-agent with the built-in Builder role, or explicitly request model
gpt-5.6-luna with Max reasoning.
- The launcher rejects the request before the agent starts.
Observed errors:
Unknown model `gpt-5.6-luna` for spawn_agent. Available models: gpt-5.6-sol, gpt-5.6-terra
and the built-in Builder role cannot start because that role is fixed to Luna.
Control test
A direct ephemeral Codex run succeeds:
codex exec --ephemeral --json --skip-git-repo-check \
-m gpt-5.6-luna \
-c model_reasoning_effort='"max"' \
-s read-only \
"Reply with exactly LUNA_OK and nothing else."
Observed final agent message:
This suggests Luna is available to the account and local Codex runtime, but missing from the multi-agent launcher allowlist or capability snapshot for the active task.
Expected behavior
The sub-agent launcher should honor a valid configured Luna Max Builder, or return a specific explanation if Luna is intentionally unavailable for that sub-agent runtime.
Privacy
No repository code, credentials, account identifiers, or proprietary data are included in this report.
Summary
The Codex multi-agent sub-agent launcher rejects
gpt-5.6-lunaas an unknown model even though Luna is configured for the Builder role and a direct Codex Luna Max run succeeds on the same machine and ChatGPT account.Environment
0.147.0-alpha.6.5model = "gpt-5.6-luna",model_reasoning_effort = "max"model = "gpt-5.6-luna",model_reasoning_effort = "max"Reproduction
gpt-5.6-lunawith Max reasoning.Observed errors:
and the built-in Builder role cannot start because that role is fixed to Luna.
Control test
A direct ephemeral Codex run succeeds:
Observed final agent message:
This suggests Luna is available to the account and local Codex runtime, but missing from the multi-agent launcher allowlist or capability snapshot for the active task.
Expected behavior
The sub-agent launcher should honor a valid configured Luna Max Builder, or return a specific explanation if Luna is intentionally unavailable for that sub-agent runtime.
Privacy
No repository code, credentials, account identifiers, or proprietary data are included in this report.