seisei_apple 0.1.0-dev.4

Apple Foundation Models provider and Flutter bridge for Seisei.

seisei_apple

Apple Foundation Models provider boundary and Flutter bridge for Seisei.

This package contains:

• AppleFoundationModelsProvider, which implements Seisei's generic provider contract.
• FmCliBackend, a local /usr/bin/fm backend for development probes.
• MethodChannelAppleFoundationModelsBackend, a Flutter method-channel backend for iOS and macOS apps.

First Run

On macOS 27 machines that provide /usr/bin/fm, the fastest smoke path is:

fm available --model system
fm respond --no-stream 'Reply with exactly: seisei-ok'

To verify Seisei itself can use local AFM, run the package smoke command:

dart run bin/local_afm_smoke.dart
dart run bin/local_afm_smoke.dart --schema
dart run bin/local_afm_smoke.dart --stream

That command uses FmCliBackend, AppleFoundationModelsProvider, and SeiseiClient to send the prompt through the local system model. A passing run prints providerId: apple_system and response: seisei-ok. The --schema variant also writes a temporary ObjectSchema FoundationModels schema file and expects response: seisei-schema-ok. The --stream variant verifies that real streaming chunks arrive and that Seisei emits a terminal value.

To verify PCC from the same Seisei path, run:

dart run bin/local_afm_smoke.dart --mode pcc

That command requires fm available --model pcc to report PCC availability in the same terminal/process context. On macOS 27, PCC checks can be context-sensitive: an interactive terminal can report PCC available while a non-interactive Dart subprocess reports PCC inference is not available in this context. If that happens, the local system model can still work while PCC is unavailable to that Seisei validation path.

From the repository root, dart tool/validate.dart --local-afm checks only the system-model path. Use dart tool/validate.dart --local-pcc when you want PCC to be a required local smoke test.

For a minimal Flutter host, create an app and point seisei_apple at this workspace with a path dependency:

flutter create --platforms=macos /tmp/seisei_afm_host

dependencies:
  seisei_apple:
    path: /path/to/your/seisei/packages/seisei_apple

Then use the native bridge directly from lib/main.dart:

final backend = MethodChannelAppleFoundationModelsBackend();
final availability = await backend.availability();
final response = await backend.respond(
  const AppleFoundationModelsRequest(
    prompt: 'Reply with exactly: seisei-ok',
    mode: AppleFoundationModelsMode.system,
  ),
);

For schema-backed generation, encode the generic Seisei object schema into a FoundationModels schema file and pass that file through provider metadata:

const encoder = FoundationModelsSchemaEncoder();
const schema = ObjectSchema(
  name: 'Draft',
  fields: {
    'count': ObjectField.integer(),
    'published': ObjectField.boolean(),
    'title': ObjectField.string(),
  },
);
final schemaFile = await encoder.writeObjectFile(schema);

final provider = AppleFoundationModelsProvider(
  backend: MethodChannelAppleFoundationModelsBackend(),
);
final response = await SeiseiClient(provider: provider).generate(
  GenerationRequest<String>(
    prompt: 'Reply as JSON with title, count, and published fields.',
    metadata: encoder.metadataForFile(schemaFile),
    decode: (rawValue) {
      final object = schema.decode(rawValue, (value) => value);
      return object['title']! as String;
    },
  ),
);

The native bridge is intentionally narrow. It checks system-model availability and sends plain system-model prompts through FoundationModels.LanguageModelSession. It can also send schema-backed system model requests when schemaPath points to a JSON-encoded FoundationModels schema file, and it streams system-model text through a Flutter event channel. The current FoundationModelsSchemaEncoder covers flat ObjectSchema values with string, integer, number, boolean, array, and optional fields. PCC is not implemented in the native bridge yet.

If you want the typed Seisei client layer, add a direct seisei dependency in the host app and build AppleFoundationModelsProvider on top of the native backend. Keep the request in system mode and avoid PCC settings. For schema-backed requests outside FoundationModelsSchemaEncoder, use AppleFoundationModelsProvider.schemaPathMetadataKey with a provider-specific FoundationModels schema file.

CI tests use fake and mocked method-channel backends; /usr/bin/fm and local Apple Foundation Models are optional validation only.