Spike-2B-MLX

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Spike-2B · MLX (4-bit)

Spike is the on-device assistant in the Spike AI iOS app. This is the build that runs on your iPhone — 4-bit MLX, served via mlx-swift. 📱 Get it on the App Store: https://apps.apple.com/app/spike-ai/id6749781844

A LoRA fine-tune of Qwen/Qwen3.5-2B (a vision-language model), specialized for Spike's on-device tool-calling — reminders, calendar, Apple Home, maps, web, files, code, and the SSH/agent toolset — plus vision (read a flyer → create the event, a note → a reminder, a receipt → the total). English and German. It emits Spike's text tool grammar:

tool:<name> {"key":"value"}

Files

4-bit MLX weights (model.safetensors, ≈1.7 GB total) + tokenizer, processor, and chat template. Load with mlx-swift / mlx-vlm on Apple silicon.

Qwen3.5 is a new hybrid (linear-attention + full-attention) architecture. It runs in the Spike app's mlx-swift runtime (which implements qwen3_5); a text-only GGUF build is also available for llama.cpp servers.

Eval — Spike harness (before → after)

Trained in three stages — text + thinking + general + German (≈22.5k samples), an 800-image vision-replay stage, then a conversation-repair stage (distilled base-model chat + contrastive tool/vision replay) — so the model keeps its enable_thinking reasoning and vision, speaks Spike's tool grammar, and does not hijack casual chat into tool calls (normal-chat tool-leak 0%).

Usage notes

• Trained on Spike's compact system prompt; use that exact prompt for best results.
• Supports optional reasoning via the enable_thinking chat-template kwarg.
• Vision: pass an image with the user turn; the model reads it and answers or calls a tool.
• Tool calls are plain text tool:<name> {json} — one per turn.

License

Derivative of Qwen3.5-2B under the Apache 2.0 License.