fix: bootstrap linuxbrew for skills

src/infra/brew.ts

@@ -0,0 +1,71 @@
+import fs from "node:fs";
+import os from "node:os";
+import path from "node:path";
+
+function isExecutable(filePath: string): boolean {
+  try {
+    fs.accessSync(filePath, fs.constants.X_OK);
+    return true;
+  } catch {
+    return false;
+  }
+}
+
+function normalizePathValue(value: unknown): string | undefined {
+  if (typeof value !== "string") return undefined;
+  const trimmed = value.trim();
+  return trimmed ? trimmed : undefined;
+}
+
+export function resolveBrewPathDirs(opts?: {
+  homeDir?: string;
+  env?: NodeJS.ProcessEnv;
+}): string[] {
+  const homeDir = opts?.homeDir ?? os.homedir();
+  const env = opts?.env ?? process.env;
+
+  const dirs: string[] = [];
+  const prefix = normalizePathValue(env.HOMEBREW_PREFIX);
+  if (prefix) {
+    dirs.push(path.join(prefix, "bin"), path.join(prefix, "sbin"));
+  }
+
+  // Linuxbrew defaults.
+  dirs.push("/home/linuxbrew/.linuxbrew/bin", "/home/linuxbrew/.linuxbrew/sbin");
+  dirs.push(path.join(homeDir, ".linuxbrew", "bin"));
+  dirs.push(path.join(homeDir, ".linuxbrew", "sbin"));
+
+  // macOS defaults (also used by some Linux setups).
+  dirs.push("/opt/homebrew/bin", "/usr/local/bin");
+
+  return dirs;
+}
+
+export function resolveBrewExecutable(opts?: {
+  homeDir?: string;
+  env?: NodeJS.ProcessEnv;
+}): string | undefined {
+  const homeDir = opts?.homeDir ?? os.homedir();
+  const env = opts?.env ?? process.env;
+
+  const candidates: string[] = [];
+
+  const brewFile = normalizePathValue(env.HOMEBREW_BREW_FILE);
+  if (brewFile) candidates.push(brewFile);
+
+  const prefix = normalizePathValue(env.HOMEBREW_PREFIX);
+  if (prefix) candidates.push(path.join(prefix, "bin", "brew"));
+
+  // Linuxbrew defaults.
+  candidates.push("/home/linuxbrew/.linuxbrew/bin/brew");
+  candidates.push(path.join(homeDir, ".linuxbrew", "bin", "brew"));
+
+  // macOS defaults.
+  candidates.push("/opt/homebrew/bin/brew", "/usr/local/bin/brew");
+
+  for (const candidate of candidates) {
+    if (isExecutable(candidate)) return candidate;
+  }
+
+  return undefined;
+}