Codex CLI 0.164.0, released on October 23, 2026, adds inline model and permission arguments and fixes restoration of saved settings when resuming sessions. After an environment update, record both the application version and the skill package you are testing. If you also edit the skill, keeping a recoverable package helps separate the two changes. This guide does not claim the CLI update changed your particular skill.
A small edit to a skill can change many future outputs. Keep a recoverable copy of the entire working package before updating instructions, references or scripts. A changelog cannot restore deleted content.
Change one behavior at a time
Give the new package a clear revision identifier and describe the intended difference. Keep two or three stable sample tasks outside the package, together with the checks that matter. Use invented or approved sample data rather than private production documents.
Suppose a product-description skill gains a shorter opening paragraph. The test should check that opening and also that units and required terms survive. Matching the previous wording exactly is not the goal; preserving the required behavior is.
Keep a usable rollback
Run old and new versions in the same compatible environment. If the new one fails, restore the saved package and confirm discovery still works. Record the failure and revision used. Do not announce an improvement based only on the skill file passing a syntax check.
Restoring the package does not restore a previous model, app version or permission profile. Record those separately and compare like with like before attributing a difference to the skill.