Support /personality for remote models

[regenrek]

What version of Codex is running?

0.92

What subscription do you have?

Pro

Which model were you using?

gpt-codex-5.2

What platform is your computer?

MacOS

What terminal emulator and version are you using (if applicable)?

Ghostty

What issue are you seeing?

Remote models can hide /personality on fresh installs (template omitted → supports_personality false)

• remote_models is enabled by default (codex-rs/core/src/features.rs).
• TUI only enables /personality when the current model preset has supports_personality = true (codex-rs/tui/src/chatwidget.rs).
• When remote /models omits model_instructions_template (or sends null), converting remote ModelInfo → ModelPreset yields supports_personality = false.
• Remote presets take precedence for overlapping slugs, so they can overwrite the built-in preset that otherwise supports personality.

What steps can reproduce the bug?

• Fresh install / clean config.
• Ensure remote_models = true (default).
• Backend /models response for gpt-5.2-codex (or another model expected to support personality) has -model_instructions_template: null.
• Open TUI and type / → /personality is missing / disabled.

What is the expected behavior?

/personality should remain available for models that support it (at least for known bundled models).

Actual: /personality can be hidden because remote metadata overwrote supports_personality

Additional information

Proposed fix:

• Backend (preferred): always include model_instructions_template for personality-capable models, or add an explicit supports_personality boolean in /models.
• Client (safe UX fix): when merging remote + bundled presets for the same slug, preserve supports_personality=true if the bundled preset supports it and remote metadata doesn’t indicate support.