ToolNeuron

On-device AI for Android. No Google Play services, no telemetry, no cloud. Models, chats, RAG documents, and key material stay on the phone.

The point isn't to clone ChatGPT into your pocket. It's to give you a chat surface, a RAG pipeline, a voice loop, and a plugin runtime that all run with the radio off if you want them to.

What it does

• Chat against any compatible GGUF model. Streaming output, multi-turn, optional thinking mode, per-turn tok/s + TTFT + peak-memory metrics.
• Vision via colocated mmproj projector files. Image bytes cross AIDL as PFDs, never byte[].
• RAG over PDF, DOCX, XLSX, PPTX, ODT, EPUB, RTF, MD, HTML, JSON, XML, CSV, TXT. Source bytes are content-addressed; re-attach a doc to any chat from the picker.
• Voice through sherpa-onnx. Streaming TTS that chunks by sentence, tap-to-toggle STT. VITS / Piper / Whisper all work.
• HTTP server in its own :server process. OpenAI-shaped endpoints, bearer-token auth, rate limit, audit log. Material 3 web UI bundled at /.
• HuggingFace browse — full-screen explorer with the filters that matter (pipeline tag, library, params, quant, license, gated, author, dataset).
• Plugin store — install plugins from Void2377/tool-neuron-plugins on HF. Each one is a sandboxed Android module with its own Compose UI, can ship ONNX models, and runs inside the host process behind a capability gate.

What it doesn't do

Tool calling, Termux integration, anything cloud. The April 2026 scope pivot took those out and they're not coming back. Image generation (:ai_sd) and the plugin marketplace came in instead, May 2026.

Architecture

Three processes.

• :app is the UI and where trust decisions live.
• :inference runs InferenceService over the GGUF engine and sherpa-onnx. Dies with the app.
• :server is foreground (dataSync, stopWithTask=false) so it survives swipe-from-recents and keeps the HTTP listener alive.

Modules:

Security

Trust decisions live in C++ so an obfuscation bypass at the Kotlin layer doesn't grant access.

• Auth is Argon2id (t=4, m=128 MiB, p=1, outLen=32). PIN must be 6 digits and pass weak-PIN rejection.
• After verify, a 32-byte opaque session token registers with the native PolicyEngine. Every gated feature crosses JNI as PolicyEngine.isAllowed(Feature, sessionToken).
• DEK is wrapped by an Android Keystore AES-256-GCM key (StrongBox-preferred, TEE fallback) and stored XOR-masked at <filesDir>/app_bootstrap/k.bin. The crypto is the wrapped ciphertext; the XOR is anti-grep.
• Encrypted prefs at <filesDir>/app_prefs/ are sealed under HKDF(DEK, "tn.app_prefs.user_key.v1"). AuthState gets a second AEAD layer keyed on HKDF(DEK, "tn.app_prefs.auth_key.v1").
• Lockout: three free, then 1m → 5m → 15m → 1h → 4h → 12h → 24h. Tenth wipes device-side state. Clock rollback past five minutes is double-penalized.
• Panic PIN, if set, triggers hardWipe() and returns VerifyResult.Wiped — indistinguishable from "attempts exceeded".
• TOFU manifest of every .so in nativeLibraryDir, rebound to install identity ({signerHash, longVersionCode, lastUpdateTime}). Hook baseline verify catches inline hooks.
• Debugger / Frida / Xposed scans run before any auth path. Detection strings are XOR-obfuscated at compile time so strings libhxs_encryptor.so | grep -i frida returns nothing.
• FLAG_SECURE is on for PIN entry only. Chats stay screenshottable.

CLAUDE.md is authoritative for the rest, including the planned pro-license hook (PolicyEngine.is_pro_feature(fid >= 1000)).

Plugins

Plugins live at Void2377/tool-neuron-plugins on HuggingFace. Each one is a zip — manifest.json + classes*.dex + optional lib/<abi>/*.so — under plugins/<id>/<version>/. The app reads plugins.json on every screen open. No local cache. The repo is the source of truth, every time.

Install flow: tap a plugin in the in-app store, runtime streams the zip into cacheDir, verifies SHA-256 against the manifest, extracts via PluginBundle, locks dex/so as read-only (Android 14+ rejects writable dex), deletes the temp file. The plugin's classes load through DexClassLoader with plugin-api as the parent, and the host calls into Plugin.Content() — a @Composable that owns its own theme and scaffold.

Capabilities are declared in the manifest and gated by the host: hxs.read / hxs.write for storage, ai.onnx for ORT sessions, internet for network, plus camera, mic, filesystem, notifications, clipboard. If a plugin tries something it didn't declare, the gate throws SecurityException.

To add to the public store:

./gradlew :plugins:<name>:packagePlugin
# drop the zip under plugins/<id>/<version>/, add an entry to plugins.json
hf upload Void2377/tool-neuron-plugins . .

Build

# Dev loop
./gradlew :app:compileDebugKotlin
./gradlew :app:installDebug

# Release (R8 + resource shrink)
./gradlew :app:assembleRelease

Release signing reads from local.properties:

TN_KEYSTORE_PATH=/abs/path/to/keystore.jks
TN_KEYSTORE_PASSWORD=...
TN_KEY_ALIAS=...
TN_KEY_PASSWORD=...

Missing keys fall back to an unsigned release so the dev flow stays open. compileSdk 37, minSdk 31, ABI filters arm64-v8a + x86_64, JVM 17.

:hxs_encryptor fetches BoringSSL and liboqs via CMake FetchContent. :native-server fetches cpp-httplib v0.18.5 and nlohmann/json v3.11.3 the same way. The LSP sometimes flags missing openssl/mem.h; that's a false positive — build-green is the source of truth.

Repo conventions

• HXS-only persisted storage. No SharedPreferences / Room / DataStore / raw files, with two intentional exceptions: the bootstrap DEK blob and content-addressed RAG source bytes.
• Single Scaffold. AppScaffold is the only one. Per-route top bars dispatch from AppTopBar.kt; bottom bars from AppBottomBar.kt. Screens take innerPadding: PaddingValues and render plain Column / LazyColumn / Box.
• No comments in source except a one-liner for non-obvious why. No decorative banners. Names and structure self-document.
• Only :app minifies. Library modules collide on Type a.a is defined multiple times against pre-minified prebuilt jars (e.g. gguf_lib-release-runtime.jar) if they pre-minify too. Library rules go in each module's consumer-rules.pro.
• Conventional commits. No Co-Authored-By trailer.
• CLAUDE.md at the repo root is project memory. Spec / plan / research / TODO docs don't go in the tree.

License

MIT.

Credits

• llama.cpp / GGUF (Liquid AI fork) via prebuilt AAR
• sherpa-onnx via prebuilt AAR
• BoringSSL, liboqs, cpp-httplib, nlohmann/json — fetched at build time
• Apache Commons Compress for .tar.bz2 voice archives
• Tabler-derived icon set