First release. Enough to replace one repository's make, and no more.

• xtask.yaml parsing with --validate, and errors that name the line rather than the file.
• The graph: needs, then, cycle detection with the cycle spelled out, run-once per invocation, declared order, and the five exit codes — 4 included, for a body that succeeded and a continuation that did not.
• Bodies: run as argv, do naming a verb the project registered, args, argv-from, each, in, env. Executable resolution honours PATH, PATHEXT and the fact that Windows cannot start a batch shim directly.
• env-required, checked before a body runs. The engine installs nothing.
• Sets: lists and globs with exclusions, expanded by the engine in a deterministic order. An expansion matching nothing is an error.
• Gate sets, the collects: derivation, --list and --gate-members, and log-grouping markers on a host that folds output.
• The remove primitive, which is the whole built-in list.
• --dry-run, printing what a run resolves to rather than what is written.
• --emit-schema, a JSON Schema for editors, generated from the same key lists the parser refuses unknown keys with.
• A mode that takes a name takes it either way — --why build and --why=build — because one flag taking both spellings and the rest taking one is a rule nobody can hold.
• --why, which names every entry point that reaches a task and spells the route edge by edge, saying whether each edge is a needs: or a then:.
• --check-ci, which reads the workflow files and reports a shell step that names a command instead of a gate set, and a gate set with no job to run it.
• --keep-going, and --parallel, which is the one place a promise is deliberately broken: output is collected per task and printed when that task ends, so the run says how wide it is and that the silence is expected.
• What each task took, printed after the last section rather than beside the task, because a line inside a fold is invisible to somebody who has expanded nothing.

Deliberately not here: --emit-ci, --dry-run output formats, a watch mode, coloured output, shell completion. Each is a real convenience and each is a place to hide a second list.