delegate_task's per-task completion display emitted lines like
"✓ [1/3] Research done (17.92s)" via a bare print(). Under ACP (and any
headless JSON-RPC stdio host where AIAgent routes human output to stderr
via a custom _print_fn), these landed on stdout and corrupted the
protocol frame stream, surfacing as "Failed to parse JSON message: ✓
[3/3] …" in the ACP adapter.
Add _emit_parent_console() which prefers parent_agent._safe_print (the
same hook AIAgent uses for every other user-facing print) and falls back
to print() only when no router is wired up or it raises. CLI behavior is
unchanged.
The PR's other fix (preset toolset expansion) is already covered on main
by _expand_parent_toolsets(), so only the stdio-safe printing change is
salvaged here.
cd9f5cc671