| --- |
| pretty_name: "From GGUF to Native MLX: A Reproducible Fable Migration and the Memory Policy That Blocked It" |
| license: mit |
| language: |
| - en |
| tags: |
| - apple-silicon |
| - mlx |
| - quantization |
| - speculative-decoding |
| - local-deployment |
| - memory-policy |
| - deployment-report |
| task_categories: |
| - text-generation |
| size_categories: |
| - n<1K |
| configs: |
| - config_name: default |
| data_files: results/processed/evidence.json |
| --- |
| |
| # From GGUF to Native MLX |
|
|
| A reproducible migration of the TURBO-Fable 27B checkpoint to native MLX on an |
| Apple M4 Max, the speculative-decoding measurements that bounded it, and the |
| serving-runtime memory policy that blocked real agent traffic. |
|
|
| **Chengyi Xu and Nexora** — Nexora Research, October 2026. |
|
|
| - Paper: [`paper/main.pdf`](paper/main.pdf) (7 pages) |
| - Source: [`paper/main.tex`](paper/main.tex) |
| - Evidence: [`results/processed/evidence.json`](results/processed/evidence.json) |
| - Protocol: [`protocol.md`](protocol.md) |
|
|
| ## What this report establishes |
|
|
| 1. **A bounded, verifiable conversion.** A mixed-precision MLX artifact was |
| produced from the pinned BF16 parent without materializing the checkpoint: |
| 128-row chunks, 3.08 GB peak resident memory, 493 s conversion body time. |
| All 686 non-quantized tensors matched the pinned sanitizer element by |
| element; sampled rows of six real modules matched official quantization |
| byte for byte; all 2,180 tensor names and shapes matched. |
|
|
| 2. **Speculation helps, but not enough, and not everywhere.** On one |
| 8,159-token prompt, DFlash2 reached 8.40 tok/s against 5.34 plain |
| (1.57× decode, ~13% on the whole request) in the best of four interleaved |
| conditions. A newer kernel generation and a wider prefill both erased the |
| gain. Stock MLX-VLM MTP gave 6.05 against 5.08. **No condition reached |
| 20 tok/s.** |
|
|
| 3. **Both real agent sessions timed out.** MTP depth 3 and DFlash2 each ran |
| ~900 s with 25,778-token initial input, made 4 and 6 tool calls, left the |
| injected defect unfixed, and failed the independent gate and full suite. |
|
|
| 4. **The blocking failure was policy, not the model.** A serving-runtime |
| system-memory guard refused an ~25k-token prefill because macOS held |
| 16.7 GiB compressed and free pages sat under a 1.7 GiB floor. Disabling |
| that documented guard — leaving the 36 GiB engine budget intact — turned |
| the identical 25,676-token request into a completed reply in 359.85 s, |
| with no prompt, tool or budget reduction. |
|
|
| 5. **Twelve protocol checks pass.** OpenAI Chat Completions, OpenAI Responses |
| and Anthropic Messages each answered on both the native backend and the |
| Magpie gateway, streaming and non-streaming, with exact markers and |
| terminal stream events. |
|
|
| ## What this report does not claim |
|
|
| - **No peer review.** This is a deployment engineering report. |
| - **No ranked intelligence.** We did not measure reasoning or coding accuracy |
| beyond one injected-defect task, which failed. |
| - **No 20 tok/s floor.** No configuration reached it. |
| - **No near-limit context qualification.** 262,144 is allocation metadata |
| here; the largest recorded actual request is 32,014 tokens. |
| - **No equivalence claim** between the MLX quantization and the BF16 parent, |
| or between the MLX artifact and the GGUF release. Layout and sampling were |
| verified; task accuracy was not. |
| - **No endorsement of ``uncensored``/``Heretic`` use.** Those are provenance |
| labels; no refusal-removal or harmful-generation evaluation was performed. |
|
|
| ## Reproducing the evidence |
|
|
| ```bash |
| python3 code/export_evidence.py results/processed/evidence.json |
| python3 code/test_export_evidence.py |
| cd paper && SOURCE_DATE_EPOCH=1761696000 tectonic --untrusted main.tex |
| ``` |
|
|
| `SOURCE_DATE_EPOCH` is required for a byte-identical rebuild: without it the |
| PDF embeds the build timestamp and its SHA-256 changes on every run. With it |
| the PDF is reproducible, which is what makes `SHA256SUMS` meaningful. |
|
|
| The exporter is whitelist-only. It reads finite scalars and enumerated flags, |
| rejects any string carrying a private path or credential marker, and refuses |
| to write an artifact whose serialized form contains one. Prompts, tool output, |
| repository source, agent transcripts and absolute local paths are excluded by |
| construction, and the test suite proves that a poisoned input is refused. |
|
|
| ## Artifact contents |
|
|
| ``` |
| paper/main.tex LaTeX source |
| paper/main.pdf built paper, 7 pages |
| paper/nexora-paper.sty |
| code/export_evidence.py whitelist-only exporter |
| code/test_export_evidence.py contract tests |
| results/processed/evidence.json |
| protocol.md |
| SHA256SUMS |
| ``` |
|
|
| ## Licence and citation |
|
|
| Code and text: see [`LICENSE`](LICENSE). The model weights are governed by |
| their upstream licences and are **not** redistributed here. |
| Citation metadata: [`CITATION.cff`](CITATION.cff). |
|
|
