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LocalAI/core/gallery
mudler's LocalAI [bot]andEttore Di Giacinto ea438cdeaf feat(vllm-cpp): wire the full engine config surface through engine_args (#11159)
The backend could configure four of the engine's knobs (block size, KV block
count, max sequence length, max concurrent sequences) out of a config surface
that is considerably larger. Speculative decoding, prefix caching, the
chunked-prefill token budget, the scheduling policy and the external KV
connector were reachable from vllm.cpp's own HTTP server and from nothing
LocalAI could write in a model config.

Config now goes through `engine_args:`, the same map the vLLM and SGLang
backends take, with keys spelled as vLLM's own CLI flags so a speculative_config
or kv_transfer_config block written for vLLM works verbatim. The legacy
`options:` list keeps working and reads every key too; engine_args wins where
both set one. Unknown keys are logged and ignored rather than fatal: the field
is shared with the other engines, so a config carrying their knobs must not take
the model down.

Two details worth knowing:

`enable_prefix_caching: false` maps to the ABI tri-state force-OFF (2), not 0.
0 means "let the model capability decide" and dense architectures default the
cache on, so collapsing the two would silently enable it against an explicit
false. enable_jump_forward (ABI v10) shares the encoding, deferring to
VT_ENABLE_JUMP_FORWARD instead of to the model.

The importer probes config.json on a vllm-cpp import and writes
speculative_config: {method: mtp} when the checkpoint declares an MTP head, the
safetensors analogue of the llama-cpp importer's GGUF probe. DFlash draft repos
are refused with a warning instead, since a drafter cannot serve alone and the
pairing is not derivable from either repo. The draft path is resolved against
LocalAI's model directory, because the engine only looks in a directory holding
config.json or in the HF cache and never downloads: the repo-id spelling the
vLLM docs teach used to die deep in the load with "draft checkpoint not found".

docs/content/features/text-generation.md gains a vllm.cpp section covering the
engine_args table, all three speculative methods, LMCache and the legacy list.
The backend had no documentation page before.

This replaces a branch that had gone stale behind master and carried its own
route to ABI v10, which #11386 has since landed in minimal form. Rebased onto
that as a single commit rather than replaying the intermediate steps, whose
ABI v9 mirrors no longer make sense against master's pin. The Darwin build
fixes for Apple Clang's gnu-folding-constant diagnostic on C++, Objective-C and
Objective-C++, originally authored by localai-org-maint-bot, are folded in here.

Verified: `make abi-check` agrees at v10; unit specs, core/config and
core/gallery/importers green; and the full e2e passes in 1330s against a CPU
libvllm.so reporting ABI v10 with Qwen_Qwen3.5-0.8B-Q4_K_M.gguf (load, blocking
completion, streaming, chat and tool calls).

Assisted-by: Claude:claude-fable-5 golangci-lint

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Co-authored-by: Ettore Di Giacinto <mudler@localai.io>
2026-08-06 12:10:56 +02:00
..
2026-03-30 00:47:27 +02:00