Connecting Ollama in Codex App writes top-level model_provider + model_catalog_json, hiding OpenAI models and causing 404s for gpt-5.5

What version of Codex is running?

codex-cli 0.142.5 / Codex App 26.623.81905 (macOS)

What issue are you seeing?

Connecting the Codex desktop app to Ollama persists top-level keys into ~/.codex/config.toml:

model_provider = "ollama-launch-codex-app"
model_catalog_json = "/Users/ummi/.codex/ollama-launch-models.json"

These globally hijack every subsequent Codex session (CLI and app), not just the Ollama one:

1. OpenAI models disappear from the model picker. When model_catalog_json is set, load_model_catalog (codex-rs/core/src/config/mod.rs) replaces the catalog, and the TUI picker (codex-rs/tui/src/chatwidget/model_popups.rs, try_list_models()) lists only catalog entries — so only Ollama models are selectable and gpt-5.5/gpt-5.4 etc. vanish.
2. 404s against localhost. model = "gpt-5.5" is still set while the default provider is now Ollama, so requests go to http://127.0.0.1:11434/v1/responses and fail with 404 model 'gpt-5.5' not found. This appears to be the root cause behind #30647 / #29703 / #29848, and is related to the picker filtering in #19694.

Notably the app also writes a correct scoped [profiles.ollama-launch] with model_provider = "ollama-launch" — the top-level writes are redundant with it and are what causes the breakage.

What steps can reproduce the bug?

1. Have a working OpenAI-authenticated Codex setup.
2. In the Codex app, connect to Ollama (launch/connect local models flow).
3. Inspect ~/.codex/config.toml: top-level model_provider and model_catalog_json now point at Ollama.
4. Start a new Codex session: the model picker no longer shows OpenAI models; selecting/keeping gpt-5.5 yields 404 Not Found: model 'gpt-5.5' not found from 127.0.0.1:11434.

What is the expected behavior?

Connecting a local provider should be additive, not a global takeover:

• The Ollama flow should scope its settings to the profile it already creates ([profiles.ollama-launch]) instead of writing top-level model_provider / model_catalog_json.
• Alternatively (or additionally), when model_catalog_json is set, the picker should merge the custom catalog with the built-in OpenAI presets (or scope the catalog to its provider) rather than replacing them, so users can switch back without hand-editing config.toml.
• If the default provider is switched, model should be remapped to a model that exists on that provider rather than left pointing at gpt-5.5.

Workaround

Delete the two top-level lines (model_provider = "ollama-launch-codex-app", model_catalog_json = ...) from ~/.codex/config.toml; the Ollama profile keeps working via codex --profile ollama-launch.

Additional information

Happy to submit a PR for the merge-instead-of-replace behavior in the catalog/picker path if maintainers agree with the direction.