Fix spawn failures being misreported as CLI unavailable

Only classify VcsProcessSpawnError as GitHubCliUnavailableError when the
underlying cause is ENOENT (binary not found). Other spawn failures such
as EACCES (permission denied) now correctly fall through to
GitHubCliCommandError instead of misleading users to install gh.

Author: cursoragent

apps/server/src/sourceControl/GitHubCli.ts

@@ -161,6 +161,14 @@ export type GitHubCliError = typeof GitHubCliError.Type;
 
 export const isGitHubCliError = Schema.is(GitHubCliError);
 
+function isEnoentCause(cause: unknown): boolean {
+  if (typeof cause === "object" && cause !== null && "code" in cause) {
+    return (cause as { code: unknown }).code === "ENOENT";
+  }
+  const text = String(cause).toLowerCase();
+  return text.includes("enoent") || text.includes("command not found");
+}
+
 export function fromVcsError(
   context: {
     readonly operation: "execute";
@@ -170,7 +178,10 @@ export function fromVcsError(
   error: VcsError,
 ): GitHubCliError {
   if (error._tag === "VcsProcessSpawnError") {
-    return new GitHubCliUnavailableError({ ...context, cause: error });
+    if (isEnoentCause(error.cause)) {
+      return new GitHubCliUnavailableError({ ...context, cause: error });
+    }
+    return new GitHubCliCommandError({ ...context, cause: error });
   }
 
   if (error._tag === "VcsProcessExitError") {