Feature request: support `fork_context` in custom subagent config

[janbam]

What variant of Codex are you using?

CLI

What feature would you like to see?

spawn_agent exposes fork_context, but custom subagent frontmatter/config cannot express the same capability.

This creates a config/runtime mismatch: context inheritance is available at spawn time, but not in the declarative definition of a reusable subagent.

For subagents that depend on caller-thread context, this forces an execution property to live in ad hoc spawn logic instead of the agent definition itself.
The imperative API and the declarative config layer are out of sync on a meaningful feature.

Feature request:

• add declarative support for context inheritance in custom subagent config
• define precedence relative to explicit spawn_agent arguments

Additional information

No response

[gudzenkov]

Also seeing a repeated failure for codex to spawn sub-agents properly

The first delegation attempt failed on tool constraints: forked agents can’t also override agent_type. I’m retrying with explicit roles and a self-contained brief instead of history forking.

My config.toml related snippet -

[features]
multi_agent = true

[agents]
max_threads = 6
max_depth = 1

[agents.architect]
description = "Design and architecture decision documentation"
config_file = "agents/architect.toml"

My sub-agent template -

name = "architect"
description = "Design and architecture decision documentation"
model = "gpt-5.4"
model_reasoning_effort = "xhigh"
sandbox_mode = "workspace-write"
nickname_candidates=["Architect"]
developer_instructions = "...."