Sandbox mode forced as read only

What version of Codex is running?

0.46.0

Which model were you using?

other

What platform is your computer?

Darwin 24.6.0 arm64 arm

What steps can reproduce the bug?

So I start the codex with a custom profile and custom model provider.

I use /status command to see what's up:
│ Approval: on-request │
│ Sandbox: workspace-write

Good, I make the first request and inspect what's sent:

<environment_context> <cwd>/Users/*******</cwd> <approval_policy>on-request</approval_policy> <sandbox_mode>read-only</sandbox_mode> <network_access>restricted</network_access> <shell>zsh</shell> </environment_context>

Problem: can only use the model in readonly mode.
config.toml:

# use OpenAI Responses API by default; env overrides are respected
[model_providers.****]
name = "OpenAI"
base_url = "******"   # overridden by $OPENAI_BASE_URL
wire_api = "chat"                   # or "chat" for Chat Completions clones
request_max_retries = 3
env_key = "OPENAI_API_KEY"

[profiles.custom]
model = "****"
model_provider = "****"
approval_policy = "on-request"
sandbox_mode = "workspace-write"
model_reasoning_effort = "high"
model_reasoning_summary = "detailed"

I start it via codex --profile custom.

What is the expected behavior?

To work

What do you see instead?

Not working :))

Additional information

_No response_