* Studio: Auto disables MTP for MLA models (GLM-5.2 et al.); UNSLOTH_MLA_MTP_ENABLED to re-enable
Studio's Auto speculative mode promotes any embedded-MTP model >=3B to
--spec-type draft-mtp. For MLA models (GLM-5.2/DeepSeek/Kimi) that is a
regression: llama.cpp's MLA/DSA MTP path keeps a duplicated full target-KV
context and recomputes the sparse-attention indexer every draft step, so it
runs ~2x slower than no speculation (GLM-5.2 UD-IQ1_S bench: 27 vs 45 tok/s,
flat across draft depth 1..6 and 96-100% acceptance, on both prose and code).
vLLM/SGLang get a speedup from the same model, so this is a llama.cpp
implementation gap, not a model property.
Auto now drops embedded MTP for MLA models and falls back to ngram-mod (or
spec-off when the binary lacks ngram-mod), mirroring the existing sub-3B
fallback. The metadata separator is kv_lora_rank: it is present on MLA models
and absent on non-MLA embedded-MTP models (Qwen3.x-MTP), whose MTP module is
structurally identical but fast, so a "full layer" heuristic cannot tell them
apart. Qwen MTP, separate drafters (Gemma, --model-draft), and non-MTP models
are unchanged.
Explicit overrides still engage the slower MTP route: choosing MTP / MTP+Ngram
in Settings, or passing --spec-type in extra args. UNSLOTH_MLA_MTP_ENABLED=1
re-enables Auto promotion for MLA once the upstream path is optimized.
A new spec_fallback_reason value "mla_mtp_disabled" surfaces this as an
Auto-mode policy downgrade (not a binary/update problem), with a settings
banner that points users at the MTP override. It is deliberately kept out of
the "Update llama.cpp" affordance since updating does not help.
Tests: resolver-matrix rows for MLA->ngram-mod / MLA-no-ngram->off /
non-MLA-Qwen->draft-mtp / MLA-separate-drafter->draft-mtp /
non-MTP-MLA->default / forced mtp|mtp+ngram on MLA->draft-mtp / env flag;
kv_lora_rank metadata fixtures; and reload-skip coverage (Auto ngram-mod is
idempotent, forced mtp bounces a reload).
* [pre-commit.ci] auto fixes from pre-commit.com hooks
for more information, see https://pre-commit.ci
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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
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