| # Protocol |
|
|
| Chengyi Xu and Nexora — Nexora Research, October 2026. |
|
|
| This protocol accompanies *From GGUF to Native MLX*. It states exactly what was |
| run, so that each number in the paper and in `results/processed/evidence.json` |
| can be traced to a condition. It deliberately does not publish prompts, tool |
| output, repository source or agent transcripts. |
|
|
| ## Host |
|
|
| - Apple M4 Max, 40 GPU cores, 64 GiB unified memory. |
| - One shared workstation, actively used during the runs. Sampled swap was |
| 17–19 GB; background load varied. Unrelated processes were not killed and |
| contention is not inferred to have caused any specific outcome. |
| - AC power, battery at 100%. No thermal or power-saving warning was reported. |
| Fan mode and OS power settings were not changed. |
|
|
| ## Checkpoint conversion |
|
|
| - Source: Coder390 BF16 shards at revision `a3a1170a` (49,825,162,976 + |
| 4,888,445,168 bytes) plus an 849,400,424-byte MTP sidecar; Fable used an |
| exporter declaring the same BF16 parent at revision `0542355a`. |
| - Every source file verified against a pinned byte size and full SHA-256 |
| before use. Sizes alone are never treated as integrity. |
| - Conversion ran on CPU with `mx.set_default_device(mx.cpu)`, 128-row chunks, |
| and no model instantiation. Layout rules were imported from a SHA-pinned |
| upstream sanitizer rather than reimplemented; unrecognized tensor names |
| abort the run. |
| - Peak RSS 3,082,305,536 bytes. Conversion body 493.33 s; 523.97 s including |
| source rehashing. |
| - Output verified by: full SHA-256 of all 39 files; index/header/payload |
| parity across 31 shards; element-wise equality of 686 non-quantized tensors |
| against the pinned sanitizer; byte equality of packed weights, scales and |
| biases for sampled rows of six modules against official quantization; |
| module-shape construction matching all 2,180 names with no missing or extra |
| tensors; five tokenizer parity cases and an identical thinking-low chat |
| template. |
|
|
| ### Known non-conclusion |
|
|
| A CPU BF16 quantized matmul differed from a matched float32 reference by |
| 0.048 absolute on synthetic cancellation-heavy inputs (8.2–12.4% of peak). |
| The original gate was **not** widened. Matched-float32 arithmetic on both |
| sides matched exactly. This is a CPU arithmetic property, not a GPU result; |
| GPU numerical behaviour of the artifact is unmeasured. |
|
|
| ### MTP packaging |
|
|
| An export that embeds `mtp.*` in trunk shards causes the loader to add 1.0 to |
| already-normalized RMSNorm gains, producing incoherent output and zero draft |
| acceptance. The fix repacks the MTP tensors into a sidecar in a container the |
| loader selects instead of the shards, preserving every tensor payload byte. |
| The repack re-hashes each payload; it performs no normalization, quantization |
| or reordering. Two contract tests failed before the helper existed and pass |
| after. |
|
|
| ## Synthetic conditions |
|
|
| - One prompt of 8,159 tokens, greedy, thinking at low effort, unquantized KV |
| cache, 512-token output cap. |
| - Four arms per condition in the order plain, speculative, speculative, plain. |
| - Every arm in every condition emitted the same 304 greedy tokens; parity is |
| reported per condition. |
| - Conditions: |
| 1. official mlx-vlm 0.6.15, source-trained MTP depth 3, 512-row prefill; |
| 2. mlx-dspark 0.19.0, DFlash2, derived cap 2, 512-row prefill, CPU/GPU |
| co-prefill explicitly off after its calibrator hit a Metal command-buffer |
| timeout; |
| 3. mlx-dspark 0.20.3, DFlash2, derived cap 7, newer verification kernels; |
| 4. mlx-dspark 0.19.0, DFlash2, cap 2, 2,048-row prefill. |
| - Two observations per arm, balanced order within a condition, conditions |
| themselves unpaired. Reported as configuration medians, not a runtime |
| ranking. |
| |
| ## Agent repairs |
|
|
| - Fresh clone of the real client repository at revision `45f07540`, per run. |
| - One injected defect inverts a retry-delay cap from `min` to `max`. The |
| independent gate fails before any model work; that gate, not the injected |
| edit, is the regression proof. |
| - The agent must add coverage for an initial delay exceeding the cap, restore |
| the implementation without changing the public API or status policy, and run |
| offline tests. |
| - Real Pi session through the Magpie gateway, ordinary tool and extension |
| discovery, thinking at low effort, 262,144 configured context, 4,096 output. |
| - No request-budget hook, no task-specific schema, no post-generation answer |
| repair. The agent acts only inside the isolated clone. |
| - Parent review checks restored source, remaining tracked diff, independent |
| gate and full suite. |
|
|
| ## Memory policy |
|
|
| - Observed refusal: prefill stopped at a chunk boundary; runtime reported |
| 16.7 GiB compressed, 0.6 GiB free, 1.7 GiB floor. |
| - Independently verified: quarter-of-RAM compressor line 16 GiB on this host; |
| about 9.6 GiB available supply; 1.47 GiB immediately free; 2.41 GiB derived |
| abort floor. |
| - Change: the runtime's documented system-memory guard switch was set to off |
| in the service process only. The 36 GiB engine allocator budget was left |
| unchanged. The effective value was read back from the live native child. |
| - After the change the same 25,676-token input completed in 359.85 s with the |
| exact expected marker and no reduction of tools, extensions, prompts or |
| budgets. Single before/after pair at matched input size; a quieter machine |
| cannot be fully excluded as a co-factor. |
|
|
| ## Protocol matrix |
|
|
| For each of the native backend (port 7871) and the Magpie gateway (port 3425), |
| three dialects were exercised, streaming and non-streaming: |
| `/v1/chat/completions`, `/v1/responses`, `/v1/messages`. Success required HTTP |
| 200, the exact expected marker in the answer, and — for streaming — at least |
| one text-delta event plus a terminal event. Twelve of twelve passed. |
|
|
| ## Deployment and cleanup |
|
|
| - Native 262,144 context, MTP depth 3, turbo profile, 128-row prefill, Q8 KV, |
| temperature 0.6, medium default reasoning effort. |
| - Transcript rewriting explicitly off; transcript mutation counters verified |
| at zero on the measured requests. |
| - Separate private credential; service logs filtered so browser-auth startup |
| URLs cannot leak it; wrapper terminates its own native child on shutdown. |
| - The retired abliterated checkpoint and its owned prepared cache were deleted |
| only after the replacement reported ready, the retired file's full hash |
| matched its recorded identity, and no process held it open: |
| 42,386,495,264 logical bytes across 43 entries. Logical bytes are not a |
| claim of equivalent physical reclamation under APFS. |
| - Normal Ornith and the image service were preserved and re-verified, |
| including an image handoff that restored the text backend before returning. |
|
|
| ## Reproducible build |
|
|
| `paper/main.pdf` is byte-reproducible given `SOURCE_DATE_EPOCH=1761696000`. |
| Two consecutive rebuilds with that variable produced identical SHA-256; without |
| it the embedded creation date changes the digest on every run. `SHA256SUMS` |
| records the reproducible build. |
|
|
| ## Excluded by construction |
|
|
| Prompts, tool output, repository source, agent transcripts, model weights, |
| credentials and absolute local paths. The exporter enforces this and the test |
| suite proves a poisoned input is rejected. |
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|
