Codex Desktop ignores project-local model_catalog_json for fresh project threads

This bug report was written by Codex.

Summary

Codex Desktop appears to ignore a trusted project's .codex/config.toml model_catalog_json setting when creating a fresh project thread, while the CLI/debug path from the same cwd respects it.

This prevents project-local custom model catalogs from working in Desktop, including per-model base_instructions / model_messages.instructions_template changes.

Environment

• OS: Windows
• Codex Desktop fresh-thread originator in rollout: Codex Desktop
• Desktop rollout cli_version: 0.136.0-alpha.2
• Desktop rollout source: vscode
• CLI test originator in rollout: codex-tui
• CLI test cli_version: 0.130.0-alpha.5
• Project cwd: F:\Projects\_sandbox

Project Config

Project-local config was created at:

# F:\Projects\_sandbox\.codex\config.toml
model_catalog_json = "model-catalog.json"

The referenced catalog exists at:

F:\Projects\_sandbox\.codex\model-catalog.json

The catalog was generated from the normal Codex model cache, but with the trailing ## Intermediary updates section removed from both fields for every model entry:

• base_instructions
• model_messages.instructions_template

This was done for all cached models:

• gpt-5.5
• gpt-5.4
• gpt-5.4-mini
• gpt-5.3-codex-spark
• codex-auto-review

Expected Behavior

When creating a fresh Codex Desktop thread in trusted project F:\Projects\_sandbox, Desktop should load the project-local .codex/config.toml, resolve model_catalog_json = "model-catalog.json" relative to the project .codex directory, and use the corresponding catalog entry for the selected model.

In this test, a fresh Desktop thread using gpt-5.5 should have received base instructions without ## Intermediary updates.

Actual Behavior

Fresh Codex Desktop project threads continued to receive base instructions containing ## Intermediary updates, despite the project-local catalog having that section removed from both base_instructions and model_messages.instructions_template.

Two Desktop test threads showed the issue:

codex://threads/019e90cd-abd3-7f73-99fe-2f9015a40047
codex://threads/019e90d5-47f0-7e81-861f-abe3778312d8

Inspection of the persisted rollout for 019e90d5-47f0-7e81-861f-abe3778312d8 showed:

Cwd: F:\Projects\_sandbox
Originator: Codex Desktop
Source: vscode
cli_version: 0.136.0-alpha.2
SessionHasUpdates: True
ProjectBaseHasUpdates: False
ProjectTemplateHasUpdates: False
GlobalBaseHasUpdates: True
GlobalTemplateHasUpdates: True

The Desktop session base instructions still contained the stripped section, indicating Desktop did not use the project-local catalog.

CLI Control Test

Running the CLI from the same cwd did respect the project-local catalog.

CLI test thread:

codex://threads/019e90dd-884f-7b01-b969-988e3e9f1a69

Inspection of that rollout showed:

Cwd: F:\Projects\_sandbox
Originator: codex-tui
Source: cli
cli_version: 0.130.0-alpha.5
SessionHasUpdates: False
SessionHasUpdateAsYouGo: False
ProjectBaseHasUpdates: False
ProjectTemplateHasUpdates: False
GlobalBaseHasUpdates: True
GlobalTemplateHasUpdates: True

codex debug models from F:\Projects\_sandbox also loaded the project-local catalog and reported that both base_instructions and model_messages.instructions_template no longer contained ## Intermediary updates.

Why This Matters

The documented project-local .codex/config.toml config path is useful for repo-specific model catalog overrides, including per-model base-instruction tuning. It currently appears to work in CLI/debug but not in Desktop project thread creation.

This makes it difficult to use project-local model catalog behavior in Desktop without changing global C:\Users\<user>\.codex\config.toml, which is too broad for repo-specific experiments.

Notes

One remaining initial progress note in the CLI test was expected because a separate injected AGENTS wrapper rule said:

For multi-step or tool-heavy work, start with a short progress note stating the first step.

That is separate from the model catalog behavior. The important distinction is that the CLI session did not receive the stripped ## Intermediary updates model-base section, while Desktop did.