Add `vp typecheck` command

[mizdra]

Description

After certain changes, a large number of type errors and lint errors can appear in the codebase at once.

• When adding noUncheckedIndexedAccess to tsconfig.json
• When doing a bulk find-and-replace across the codebase

In these situations, it's more efficient to fix type errors first. Type errors can cause lint errors, so fixing them may resolve lint errors automatically. By fixing type errors first and lint errors second, you can reduce the overall amount of work.

Suggested solution

To support this workflow, I'd like a vp typecheck command — a command that runs only type checking, without format or lint.

Alternative

One workaround is to use vp exec tsgo. While this works, having a dedicated command would be more approachable for beginners.

Additional context

There is already a vp lint command. By default it runs only lint, but setting lint.options.typeCheck to true also runs type checking alongside lint. So the current behavior is:

• When lint.options.typeCheck is true:
  • vp check: runs format, lint, and type check
  • vp format: runs format only
  • vp lint: runs lint and type check
  • vp typecheck: runs type check only
• When lint.options.typeCheck is false:
  • vp check: runs format, lint, and type check
  • vp format: runs format only
  • vp lint: runs lint only
  • vp typecheck: runs type check only

Since vp format runs only format and vp typecheck would run only type check, users would naturally expect vp lint to run only lint as well. Having vp lint run more than just lint when lint.options.typeCheck: true feels inconsistent and unintuitive.

Here are some possible ways to address this, though each comes with trade-offs:

• Deprecate the lint.options.typeCheck option and make vp lint always run lint only. However, this would be a breaking change for existing users.
• Add a --type-check flag to vp lint so users can opt in to type checking via the command line. However, the interaction with lint.options.typeCheck: false may be confusing.

I'd love to hear if there are better ideas for solving this.

Validations

• Read the Contributing Guidelines.
• Confirm this request is for Vite+ itself and not for Vite, Vitest, tsdown, Rolldown, or Oxc.
• Check that there isn't already an issue requesting the same feature.

[mizdra]

Thinking about this further, there are some open questions:

• Which files should vp typecheck check?
  • All files, or only those included in tsconfig.json?
  • For reference, vp lint runs type checking only on the files targeted by lint.
• Should the tsconfig.json path be configurable?
  • For example, via vp typecheck --project tsconfig.typecheck.json.
  • Should it be a CLI flag like --project, or a config option like typeCheck.options.project in vite.config.ts?

These questions suggest that a full vp typecheck command could be a fairly large undertaking.

Stepping back to why I wanted vp typecheck in the first place: my real pain point is that lint errors are mixed together in the output of vp lint. If there were a way to suppress lint errors from vp lint output, that would already satisfy my needs. So a simpler solution might be to just add a --type-check-only flag to vp lint.

[fengmk2]

Consider adding a --type-only option to vp check https://viteplus.dev/guide/check? cc @cpojer what do you think?

[cpojer]

I agree that a flag is better. I think --type-check-only is the most descriptive for this specific use case.

[jong-kyung]

@fengmk2 Hi! I would like to work on this issue. Could you assign it to me?

[kazupon]

I think that, in that case, shouldn’t we add --fmt-only and --lint-only too? 🤔

If only --type-check is available, people tend to assume that there are standalone options like these, and they often end up wanting them.

[fengmk2]

I suddenly remembered that oxlint doesn't have the "type check only" feature, right? @camc314

[cpojer]

Since we already have --no-fmt and --no-lint, it might be better not to add any *-only flags. Instead, maybe we could find a good name for type checks but no lints, or redefine --no-lint to keep running type checks, and require --no-type-check to disable lint and type-check. Then vp check --no-lint would work for this use case.