[BUG] Silent conflict when both prefer-offline=true and prefer-online=true are set, causing npm view to return stale cached data

[gmvp3]

Is there an existing issue for this?

• I have searched the existing issues

This issue exists in the latest npm version

• I am using the latest npm

Current Behavior

When both prefer-offline=true and prefer-online=true are set in the .npmrc configuration, npm silently prioritizes prefer-offline. Commands that query the registry, such as npm view version, skip the network request entirely and return stale cached data. The CLI provides no warning or error message indicating that these mutually exclusive flags are conflicting or that prefer-online is being ignored.

Expected Behavior

npm should detect when mutually exclusive flags like prefer-offline and prefer-online are active simultaneously. It should either output a clear warning message to the console (e.g., WARN config: mutually exclusive flags prefer-offline and prefer-online detected) so the user is aware of the conflict, or ensure that explicitly setting prefer-online overrides the offline preference to force a network validation.

Steps To Reproduce

No response

Environment

No response

[Jah-yee]

I have submitted a fix for this issue! The fix adds a warning message when both prefer-offline and prefer-online flags are detected, informing users that prefer-online will be ignored in favor of prefer-offline. PR: Jah-yee#1

[gmvp3]

I have submitted a fix for this issue! The fix adds a warning message when both prefer-offline and prefer-online flags are detected, informing users that prefer-online will be ignored in favor of prefer-offline. PR: Jah-yee#1

Thanks so much for the quick response and for putting together this PR! Adding a warning will definitely save a lot of developers from the headache I just went through.

Looking at this from a structural perspective, I was wondering if it might make sense in the long run to merge these two mutually exclusive boolean flags into a single configuration key?

For example, replacing both prefer-offline and prefer-online with a single option like fetch-preference=online|offline (or something similar). This would completely eliminate the possibility of a conflicting state at the configuration level, making it structurally impossible for users to confuse the CLI.

Just a thought for future iterations! Thanks again for the quick fix.

[mvanhorn]

Implemented in #9129 - adds a config conflict warning when both prefer-offline and prefer-online are set.

[owlstronaut]

we created a new bug, so i'm reverting that and reopening -- #9133