The merged UI/platform thread on macOS (Flutter 3.41) freezes on any
synchronous work — file I/O, Process.run, even isolate spawning during
early frames. No timing workaround (Timer, addPostFrameCallback,
Future.delayed) was reliable.
Fix: spawn a backend isolate that owns the DaemonDispatcher, GitClient,
PqlClient, FilesService, EditorRegistry, and Toolchain resolution. The
main isolate stays free for rendering. Communication uses SendPort with
the existing IPC message protocol (IpcRequest/IpcResponse/IpcEvent) —
zero new serialization.
New files:
backend.dart — spawns isolate, manages SendPort/ReceivePort
backend_entry.dart — isolate entry point, boots all services
isolate_client.dart — replaces InProcessClient for production
Toolchain now exposes resolveToolchainPaths() as a top-level function
with self-contained PATH expansion (no module-level state that would
prevent isolate message passing).
ClideTestApp gains boot-sequence tests: compute(), Isolate.run(),
sequential Process.run, and the full resolve+exec chain.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
