JustFit combines compressed KV execution, component swapping and state-preserving serving transitions in an MLX runtime. On a 24 GiB M4 Pro MacBook, Qwen3.8-27B MXFP4 completes 196K input tokens plus 16K output tokens in three runs. That raises completed single-request context 6.93x over the stated mlx-vlm baseline. Extreme-context runs take about 103 minutes, so the result establishes capacity more than interactive speed.
JustFit serves a 200K-token model context on a 24 GiB MacBook
2026-09-16Frontier watchTRIAL
JustFit combines compressed KV execution, component swapping and state-preserving serving transitions in an MLX runtime. On a 24 GiB M4 Pro MacBook, Qwen3.8-27B MXFP4 completes 196K input tokens plus 16K output tokens in three runs. That raises completed single-request context 6.93x over the stated mlx-vlm baseline. Extreme-context runs take about 103 minutes, so the result establishes capacity more than interactive speed.
Imported from the existing research archive. Migration preserves the recorded judgment and is not a fresh verification.
What this means for you
For local-agent teams, memory scheduling can unlock long sessions without changing model-weight quantization. The practical use is asynchronous ingestion with prefix reuse, not repeated cold 200K prompts. Reproduce the branch on your own hardware before treating the reported boundary as a deployment target.
FRONTIER WATCH
Public artifacts and validated results are different.
The recorded fact is the public work and its artifacts. Author-reported outcomes do not establish independent reproduction. Next checks include usable code, task conditions and third-party validation.
Evidence & related material
Technical details & scores
| Hardware | 24 GiB M4 Pro MacBook |
|---|---|
| Model | Qwen3.8-27B MXFP4 |
| Capacity | 196,608 input plus 16,384 output tokens; 212,992 completed positions |
| Baseline Delta | 6.93x completed single-request context over mlx-vlm baseline |
| Speed | about 48 minutes cold prefill; 4.99 tok/s at the limit; about 103 minutes total |
| Reproducibility | public evolving branch; exact historical environments incomplete |
Technical impact 4
Engineering value 4
Adoption signal 1
Maturity 2
Verification cost 3
Risk 2