Correctly-converted BF16 GGUF of Google's official google/gemma-4-E2B-it-assistant MTP (Multi-Token Prediction) drafter, for use with llama.cpp speculative decoding.

Pair this drafter with the Gemma 4 E2B target model to get ~2× decode throughput with mathematically identical output quality.

Why this GGUF exists

The community GGUFs for Google's Gemma 4 assistants use an architecture string mismatch — gemma4_assistant (underscore) instead of upstream llama.cpp's gemma4-assistant (hyphen) — which makes them fail to load on any modern llama.cpp build. Byte-patching the arch string only surfaces the next problem: metadata keys are all namespaced under the wrong architecture prefix.

This GGUF was converted directly from Google's official BF16 safetensors with llama.cpp's own convert_hf_to_gguf.py (b10215 / commit eb41d503b), so every metadata key is correctly namespaced and it loads cleanly on upstream llama.cpp.

Verified working

llama.cpp SYCL b10215+ on Intel Arc Pro B60 (Battlemage / Xe2, 24 GB)
Should also work on any llama.cpp backend (CUDA, Metal, Vulkan, CPU) at b10215 or newer, since the gemma4-assistant architecture was already merged upstream by that build

Usage (llama.cpp)

bash

llama-server \
  -m gemma-4-E2B_q4_0-it.gguf \
  --model-draft gemma-4-E2B-it-assistant-official.bf16.gguf \
  --spec-type draft-mtp \
  --spec-draft-n-max 3 \
  -ngl 99 -c 8192 -fa on -ub 2048 -b 2048 \
  --jinja --reasoning off \
  --host 0.0.0.0 --port 8000

Key flags:

--spec-type draft-mtp — use the MTP-native speculative decode path (not the classic n-gram draft)
--spec-draft-n-max 3 — Google's recommended draft length for Gemma 4 assistants
--reasoning off — required for structured-JSON workflows on Gemma 4 (otherwise output routes to reasoning_content)

Benchmark (Intel Arc Pro B60, llama.cpp SYCL b10215)

Measured on real workload (2-5K token prompts, structured JSON output):

Metric	Value
Decode	138.8 tok/s
MTP acceptance rate	67.8%
Prefill @ 2K tokens	3,681 tok/s
VRAM (target + drafter, Q4_0 target + BF16 drafter)	4.5 GiB

Compared to E2B without a drafter: +58% decode throughput. Compared to the community (broken) GGUF: N/A — the community version doesn't load.

Full bench methodology, hardware notes, and comparison to the Ornith 9B production model: github.com/srmiles/local-llm-benchmarks.

Conversion recipe (reproducible)

bash

# Prerequisites: llama.cpp b10215 or newer, torch installed
git clone https://github.com/ggml-org/llama.cpp
cd llama.cpp && git checkout b10215
pip install --index-url https://download.pytorch.org/whl/cpu torch

hf download google/gemma-4-E2B-it-assistant --local-dir gemma-4-E2B-it-assistant-hf
python convert_hf_to_gguf.py gemma-4-E2B-it-assistant-hf/ \
  --outfile gemma-4-E2B-it-assistant-official.bf16.gguf \
  --outtype bf16

BF16 was kept (no quantization) because the drafter is small — 170 MB unquantized adds negligible VRAM vs the target model, and quantizing the drafter would risk MTP acceptance regression for no meaningful footprint saving.

Files

gemma-4-E2B-it-assistant-official.bf16.gguf — 170 MB, BF16

Credits

Model weights: Google — google/gemma-4-E2B-it-assistant
MTP research: DeepMind (Google AI) — Gemma 4 MTP documentation
Conversion tool: ggml-org/llama.cpp convert_hf_to_gguf.py at commit eb41d503b (b10215)
Conversion & bench: srmiles/local-llm-benchmarks

License

Apache 2.0 — same as the upstream Gemma 4 assistant weights.

srmiles/gemma-4-E2B-it-assistant-GGUF

Gemma 4 E2B-it Assistant (MTP Drafter) — GGUF (BF16)