fix(codex): respect CODEX_HOME

[kdcokenny]

Description

respects CODEX_HOME when writing config.toml, falling back to $HOME/.codex when it's unset or empty.

the module was always writing to ~/.codex, so Codex ignored the module's settings when using a custom config directory.

Type of Change

• New module
• New template
• Bug fix
• Feature/enhancement
• Documentation
• Other

Module Information

Path: registry/coder-labs/modules/codex
New version: v5.4.2
Breaking change: [ ] Yes [x] No

Testing & Validation

• Tests pass (bun test)
• Code formatted (bun fmt)
• Changes tested locally

also i manually tested it to make sure that it failed as expected without this change and then passed as expected with the change.

Related Issues

Fixes #1157.

[35C4n0r]

CODEX_HOME is a configuration variable; imho we should add a codex_home as a variable with "" (empty, so that we don't overwrite user's CODER_HOME) as the default, and a coder_env block which conditionally sets the CODEX_HOME env if var.codex_home != "".
@matifali @Edd88-pixel thoughts ?

[Edd88-pixel]

@35C4n0r A codex_home input would be useful for convenience, but I’d keep it as a follow-up. CODEX_HOME can already be set through coder_agent.env or a separate coder_env; this PR fixes the module ignoring it

[Edd88-pixel]

@kdcokenny Have you tested this end-to-end with the Codex CLI to confirm it ?

[kdcokenny]

@kdcokenny Have you tested this end-to-end with the Codex CLI to confirm it ?

yep!