CLI's completion should know what options you've typed

Summary

Consider Git's -C option: git -C /path/to/repo checkout <TAB> When you hit Tab, Git completes branch names from /path/to/repo, not your current directory. The completion is context-aware—it depends on the value of another option. Most CLI parsers can't do this. They treat each option in isolation, so completion for --branch has no way of knowing the --repo value. You end up with two unpleasant choices: either show completions for all possible branches across all repositories (useless), or give up on completion entirely for these options. Optique 0.10.0 introduces a dependency system that solves this problem while preserving full type safety. Static dependencies with or() Optique already handles certain kinds of dependent options via the or() combinator: import { flag, object, option, or, string } from "@optique/core"; const outputOptions = or( object({ json: flag("--json"), pretty: flag("--pretty"), }), object({ csv: flag("--csv"), delimiter: option("--delimiter", string()), }), ); TypeScript knows that if json is true, you'll have a pretty field, and if csv is true, you'll have a delimiter field. The parser enforces this at runtime, and shell completion will suggest --pretty only when --json is present. This works well when the valid combinations are known at definition time. But it can't handle cases where valid values depend on runtime input—like branch names that vary by repository. Runtime dependencies Common scenarios include: A deployment CLI where --environment affects which services are available A database tool where --connection affects which tables can be completed A cloud CLI where --project affects which resources are shown In each case, you can't know the valid values until you know what the user typed for the dependency option. Optique 0.10.0 introduces dependency() and derive() to handle exactly this. The dependency system The core idea is simple: mark one option as a dependency source, then create derived parsers that use its value. import { choice...