refactor: explicit lockfile priority, derived PM type, changelog

CHANGELOG.md

@@ -0,0 +1,47 @@
+# Changelog
+
+All notable changes to this project are documented here. The format is based on
+[Keep a Changelog](https://keepachangelog.com/en/1.1.0/), and this project
+adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [0.1.3] - 2026-06-03
+
+### Fixed
+
+- **Monorepo detection now works.** The directory walk previously exited after
+  checking only the starting directory, so running `omnes` from a sub-package
+  fell back to npm instead of finding the lockfile at the repository root.
+  Detection now walks up to the filesystem root.
+- `--version` reads the version from `package.json` instead of a hardcoded
+  string that had drifted out of sync.
+- `--help` and `--version` print to stdout instead of stderr, so they pipe and
+  redirect like other CLIs.
+- A missing package manager now exits with code `127` (was `1`), matching the
+  documented API.
+
+### Added
+
+- Corepack `packageManager` field detection. An explicit
+  `"packageManager": "pnpm@9.x"` in `package.json` takes precedence over a
+  lockfile in the same directory.
+- The informational `Using:` line now shows the fully resolved command
+  (e.g. `Using bun: bun run dev`).
+- Unit tests covering traversal, Corepack detection, lockfile priority, and the
+  npm argument transform; Biome lint/format; and a GitHub Actions CI workflow.
+
+### Changed
+
+- Internal: pure detection and argument logic extracted into `src/lib.ts`, with
+  `src/omnes.ts` reduced to a thin executable entry point.
+- Internal: `LOCKFILES` is an ordered tuple array rather than an object, so
+  detection priority is explicit instead of relying on object key order. No
+  behavior change.
+- Internal: the supported package-manager list is a single `const` source of
+  truth, with the `PackageManager` type derived from it and a type guard
+  replacing a cast in Corepack-field parsing.
+
+## [0.1.2] and earlier
+
+Initial releases and documentation. See the git history for details.
+
+[0.1.3]: https://github.com/darkroomengineering/omnes/releases/tag/v0.1.3

src/lib.ts

@@ -1,25 +1,24 @@
 import { existsSync, readFileSync } from "node:fs";
 import { dirname, join } from "node:path";
 
-// Supported package managers
-export type PackageManager = "bun" | "pnpm" | "npm" | "yarn";
-
-// Lockfile → package manager. Key order is the detection priority: the first
-// match within a directory wins. Mirrors the table in the README.
-export const LOCKFILES: Record<string, PackageManager> = {
-  "bun.lockb": "bun",
-  "bun.lock": "bun",
-  "pnpm-lock.yaml": "pnpm",
-  "yarn.lock": "yarn",
-  "package-lock.json": "npm",
-};
-
-const PACKAGE_MANAGERS: ReadonlySet<string> = new Set<PackageManager>([
-  "bun",
-  "pnpm",
-  "npm",
-  "yarn",
-]);
+// Supported package managers — single source of truth for the name list. The
+// PackageManager type is derived from it so the two cannot drift.
+export const PACKAGE_MANAGERS = ["bun", "pnpm", "npm", "yarn"] as const;
+export type PackageManager = (typeof PACKAGE_MANAGERS)[number];
+
+function isPackageManager(value: string): value is PackageManager {
+  return (PACKAGE_MANAGERS as readonly string[]).includes(value);
+}
+
+// Lockfile → package manager, in detection-priority order: within a directory
+// the first match wins. Mirrors the table in the README.
+export const LOCKFILES: ReadonlyArray<readonly [string, PackageManager]> = [
+  ["bun.lockb", "bun"],
+  ["bun.lock", "bun"],
+  ["pnpm-lock.yaml", "pnpm"],
+  ["yarn.lock", "yarn"],
+  ["package-lock.json", "npm"],
+];
 
 // npm built-in commands that don't require a "run" prefix
 export const NPM_BUILTIN_COMMANDS = new Set([
@@ -128,8 +127,8 @@ export function parsePackageManagerField(
     return undefined;
   }
   const name = value.split("@", 1)[0]?.trim();
-  if (name !== undefined && PACKAGE_MANAGERS.has(name)) {
-    return name as PackageManager;
+  if (name !== undefined && isPackageManager(name)) {
+    return name;
   }
   return undefined;
 }
@@ -170,7 +169,7 @@ export function detectPackageManager(startDir: string): PackageManager {
       return hint;
     }
 
-    for (const [lockfile, pm] of Object.entries(LOCKFILES)) {
+    for (const [lockfile, pm] of LOCKFILES) {
       if (existsSync(join(currentDir, lockfile))) {
         return pm;
       }