flutter_gemma_embeddings

On-device text embeddings for flutter_gemma: Gecko / EmbeddingGemma .tflite models via the LiteRT C API + dart:ffi. Opt-in package — add it only if you compute embeddings (e.g. for on-device RAG). Android, iOS, macOS, Linux, Windows, Web.

This package is autonomous: it does not depend on flutter_gemma_litertlm, so you can use embeddings without pulling in the .litertlm inference engine. When both packages are present they share one native library (libLiteRtLm), bundled once (see Troubleshooting).

Usage

import 'package:flutter_gemma/flutter_gemma.dart';
import 'package:flutter_gemma_embeddings/flutter_gemma_embeddings.dart';

await FlutterGemma.initialize(
  embeddingBackends: [LiteRtEmbeddingBackend()],
);

LiteRtEmbeddingBackend provides the embedding model used by the auto-embedding RAG methods (addDocument / searchSimilar) and by createEmbeddingModel. Pair it with a vector store from flutter_gemma_rag_sqlite or flutter_gemma_rag_qdrant.

Web setup

On web, embeddings run via LiteRT.js. Add the loader script to your app's web/index.html <head>. Pin a release tag and include a Subresource Integrity hash so a CDN compromise cannot inject code:

<script type="module"
        src="https://cdn.jsdelivr.net/gh/DenisovAV/flutter_gemma@<tag>/web/litert_embeddings.js"
        integrity="sha384-<hash>"
        crossorigin="anonymous"></script>

Compute the hash for the tag you pin (the browser rejects the script if integrity doesn't match, so don't ship a placeholder): openssl dgst -sha384 -binary web/litert_embeddings.js | openssl base64 -A

Native platforms need no setup — the LiteRT native library is bundled at build time by the package's Native-Assets hook.

Platforms

Platform Support
Android / iOS ✅ FFI
macOS / Linux / Windows ✅ FFI
Web ✅ via LiteRT.js (CDN)

The native library is fetched at build time by hook/build.dart (Native Assets) from a SHA256-verified GitHub release — no manual setup on native platforms.

Troubleshooting

dlopen / "library not found" (libLiteRtLm) after removing flutter_gemma_litertlm

flutter_gemma_embeddings and flutter_gemma_litertlm share one native library (libLiteRtLm), bundled exactly once by whichever package's build hook ran first ("the owner"). If you had both packages, then removed the owner and rebuilt without a clean, a stale ownership marker in the shared cache can leave the library unbundled, surfacing as an opaque dlopen "no such file" on the first embedding call. Fix:

flutter clean
rm -rf ~/Library/Caches/flutter_gemma/native        # macOS / Linux
# Windows: rmdir /s "%LOCALAPPDATA%\flutter_gemma\native"  (path may vary)
flutter pub get

This is a known limitation of Dart's Native Assets build hooks: a hook is sandboxed and cannot detect which sibling packages are present in the current build, so it cannot recompute the registrant per-build (see dart-lang/native#190). It only triggers in the narrow remove-the-owner-without-clean case.

Libraries

flutter_gemma_embeddings
On-device text embeddings for flutter_gemma (LiteRT C API + .tflite).