frontend_server_kit #

Persistent frontend_server session driver for incremental kernel compile, hot reload, and VM Service compileExpression — including Flutter targets and package: URI rewriting.

Install #

dart pub add frontend_server_kit

Usage #

import 'package:frontend_server_kit/frontend_server_kit.dart';

final session = FrontendServerSession(
  FrontendServerOptions(
    dart: dartExe,
    frontendServer: snapshotPath,
    sdkRoot: patchedSdkRoot,
    packageConfig: packageConfigPath,
    entrypoint: entrypointPath,
    outputDill: outputDillPath,
    // target: 'flutter', // default
    // dartDefines: ['FOO=bar'],
  ),
);

await session.spawn();
final dill = await session.compile();
await session.accept();

// Hot reload: recompile invalidated sources, then accept or reject.
final incremental = await session.recompile(
  invalidated: ['file:///…/lib/main.dart'],
);
await session.accept();

// Hot restart needs a full kernel component next:
await session.reset();
await session.recompile(invalidated: [/* … */]);
await session.accept();

await session.close();

PackageUris maps local file paths to package: URIs via .dart_tool/package_config.json so breakpoints and recompiles match the kernel's import URIs across hosts.

Scope #

• Spawns and drives one long-lived frontend_server over stdin/stdout.
• Serializes compile / recompile / compileExpression so DevTools evaluate cannot interleave with a reload.
• Does not locate Flutter or the frontend_server snapshot for you — pass absolute paths in FrontendServerOptions.

Related #

Part of the xcross monorepo.