EvanAgent/dsh-desktop/app/env.js

"use strict";
/**
 * Binary discovery + child environment for GUI-context launches.
 *
 * From Finder/launchd an app inherits PATH=/usr/bin:/bin:/usr/sbin:/sbin — the
 * `#!/usr/bin/env node` shebangs of dsh and npm cannot resolve there. All
 * spawned children therefore run through childEnv(), which prepends the
 * directories that actually hold dsh, npm, and node: both their symlink spots
 * (~/.local/bin) and their realpath homes (e.g. a version manager under
 * ~/.hermes/node/bin).
 */
const fs = require("node:fs");
const os = require("node:os");
const path = require("node:path");

function firstExisting(candidates) {
	for (const candidate of candidates) {
		try { if (candidate && fs.existsSync(candidate)) return candidate; } catch { /* next */ }
	}
	return null;
}

function pathDirs() {
	return (process.env.PATH || "").split(":").filter(Boolean);
}

/** The dsh binary: explicit override, common user install spots, then PATH. */
function findDsh() {
	const override = process.env.DSH_DESKTOP_DSH_BIN;
	if (override) return override;
	const home = os.homedir();
	return firstExisting([
		path.join(home, ".local/bin/dsh"),
		"/opt/homebrew/bin/dsh",
		"/usr/local/bin/dsh",
		...pathDirs().map((dir) => path.join(dir, "dsh")),
	]) || "dsh";
}

/** The npm binary: the same discovery strategy. */
function findNpm() {
	const home = os.homedir();
	return firstExisting([
		path.join(home, ".local/bin/npm"),
		"/opt/homebrew/bin/npm",
		"/usr/local/bin/npm",
		...pathDirs().map((dir) => path.join(dir, "npm")),
	]) || "npm";
}

const DSH_BIN = findDsh();
const NPM_BIN = findNpm();

/**
 * Re-resolve the dsh binary right before every spawn. `npm install -g`
 * replaces the bin symlink during upgrades; a path captured at shell startup
 * (or a bare "dsh" fallback resolved while the link was missing) would then
 * hit ENOENT — exactly the upgrade-race failure seen in the wild.
 */
function resolveDsh() {
	return findDsh();
}

/** Environment (PATH augmented) for every child process we spawn. */
function childEnv() {
	const dirs = [];
	for (const bin of [DSH_BIN, NPM_BIN]) {
		if (path.isAbsolute(bin)) dirs.push(path.dirname(bin));
		try { dirs.push(path.dirname(fs.realpathSync(bin))); } catch { /* not a file */ }
	}
	dirs.push(
		path.join(os.homedir(), ".local/bin"),
		"/opt/homebrew/bin",
		"/usr/local/bin",
	);
	const unique = [...new Set(dirs.filter(Boolean))];
	return { ...process.env, PATH: `${unique.join(":")}:${process.env.PATH || ""}` };
}

module.exports = { DSH_BIN, NPM_BIN, findDsh, findNpm, resolveDsh, childEnv };