feat(shared): add connected-providers-cache for model availability (#1121)

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode)

Co-authored-by: justsisyphus <justsisyphus@users.noreply.github.com>
Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/shared/data-path.ts

@@ -20,3 +20,28 @@ export function getDataDir(): string {
 export function getOpenCodeStorageDir(): string {
   return path.join(getDataDir(), "opencode", "storage")
 }
+
+/**
+ * Returns the user-level cache directory.
+ * Matches OpenCode's behavior via xdg-basedir:
+ * - All platforms: XDG_CACHE_HOME or ~/.cache
+ */
+export function getCacheDir(): string {
+  return process.env.XDG_CACHE_HOME ?? path.join(os.homedir(), ".cache")
+}
+
+/**
+ * Returns the oh-my-opencode cache directory.
+ * All platforms: ~/.cache/oh-my-opencode
+ */
+export function getOmoOpenCodeCacheDir(): string {
+  return path.join(getCacheDir(), "oh-my-opencode")
+}
+
+/**
+ * Returns the OpenCode cache directory (for reading OpenCode's cache).
+ * All platforms: ~/.cache/opencode
+ */
+export function getOpenCodeCacheDir(): string {
+  return path.join(getCacheDir(), "opencode")
+}