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feat: add ds4 backend (DeepSeek V4 Flash) with tool calls, thinking, KV cache - #9758

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May 11, 2026
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feat: add ds4 backend (DeepSeek V4 Flash) with tool calls, thinking, KV cache#9758
mudler merged 40 commits into
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worktree-feat-ds4-backend

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Summary

Adds antirez/ds4 (DeepSeek V4 Flash inference engine) as a first-class LocalAI C++ backend at backend/cpp/ds4/. Single-model engine, optimized for Metal (Darwin) and CUDA (Linux). Wires up native ChatDelta-based tool calls, thinking-mode mapping, and a SHA1-keyed disk KV cache — none of it relying on Go-side regex fallback.

Plan + design notes live (uncommitted) at docs/superpowers/plans/2026-05-11-ds4-backend.md.

What ships

  • backend/cpp/ds4/ — fresh ~600 LoC C++ wrapper (NOT a fork of llama-cpp's grpc-server.cpp):
    • grpc-server.cpp — Health, Free, LoadModel, TokenizeString, Predict, PredictStream, Status. Compile-time backend (DS4_NO_GPU → CPU, __APPLE__ → Metal, else CUDA).
    • dsml_parser.{h,cpp} — streaming state machine for <think>, <|DSML|tool_calls>, <|DSML|invoke>, <|DSML|parameter> markers. Classifies token bytes into CONTENT / REASONING / TOOL_START / TOOL_ARGS / TOOL_END events.
    • dsml_renderer.{h,cpp} — prompt-direction: OpenAI tool_calls + role=tool messages → DSML. Also RenderToolsManifest (verbatim port of append_tools_prompt_text from ds4_server.c — required for the model to emit DSML tool calls at all).
    • kv_cache.{h,cpp} — SHA1-keyed disk cache via ds4_session_save_payload / ds4_session_load_payload. Format: DS4G magic + version + ctx_size + prefix_len + prefix + payload_bytes + payload. Enable via ModelOptions.Options[] = "kv_cache_dir:/path".
    • Makefile + CMakeLists.txt + prepare.sh (clones ds4 at pin ae302c2f) + run.sh + package.sh.
  • backend/Dockerfile.ds4 — single-stage builder → FROM scratch. Bundles libcudart/libcublas via scripts/build/package-gpu-libs.sh.
  • scripts/build/ds4-darwin.sh — native Metal build via otool -L dylib bundling, mirrors llama-cpp-darwin.sh.
  • CI matrix (.github/backend-matrix.yml): cpu-ds4 (amd64+arm64) + cuda13-ds4 (amd64+arm64); Darwin handled by backend_build_darwin.yml.
  • Importer (core/gallery/importers/ds4.go) — auto-detects antirez/deepseek-v4-gguf repo URI and DeepSeek-V4-Flash-*.gguf filename pattern. Registered BEFORE LlamaCPPImporter (specificity order). Emits backend: ds4, ds4flash.gguf local filename, AutomaticToolParsingFallback: false (we emit native ChatDelta tool calls).
  • Gallery entry for deepseek-v4-flash-q2.
  • E2E suite hook: BACKEND_BINARY env var alternative to BACKEND_IMAGE so hardware-gated backends with multi-GB models can be tested without baking the model into Docker context.

Why a fresh wrapper, not a llama-cpp fork

ds4 is a single-model engine with a clean public C API (ds4.h). Forking llama-cpp's 3000-line grpc-server.cpp would drag in HTTP server bridging, SIMD matrix variants, multimodal projector glue — all irrelevant. The fresh wrapper is ~600 LoC and maps 1:1 onto ds4's engine/session boundary.

Tool calls + thinking + KV cache details

  • DSML markers are plain text the model emits (not special tokens), so a substring-based streaming parser is sufficient and works at the token-bytes level.
  • Thinking mode mapping: Metadata["enable_thinking"]=falseDS4_THINK_NONE; Metadata["reasoning_effort"] == "max"|"xhigh"DS4_THINK_MAX; default DS4_THINK_HIGH.
  • Tools manifest injection into system prompt is load-bearing — without it the model has no idea tools exist and won't emit DSML. Verbatim port of upstream's preamble.
  • KV cache file format is our own (not bit-compatible with ds4-server's .kv files — that interop is a follow-up).

Build matrix

Build Where
cpu-ds4 (amd64 + arm64) Linux CI
cuda13-ds4 (amd64 + arm64) Linux CI + DGX Spark validation
ds4-darwin (arm64) macOS CI (Apple Silicon)

cuda12 / ROCm / Vulkan / SYCL intentionally omitted (not applicable or unvalidated upstream).

Test plan

  • Go importer tests pass — go test ./core/gallery/importers/... (33 specs, including new DS4Importer cases for auto-detect, filename pattern, pref override, and must-not-match-arbitrary-GGUFs)
  • YAML lint clean on .github/backend-matrix.yml, backend/index.yaml, gallery/index.yaml, .github/workflows/backend_build_darwin.yml
  • dsml_parser.cpp + kv_cache.cpp compile standalone (post-namespace-collision fix)
  • DSML hex-escape bug fixed (\xef\xbd\x9cD was being read as 0xCD, eating the D — split with adjacent string literals so byte sequence stays EF BD 9C 44)
  • In progress: docker-build-ds4 on a DGX Spark GB10 (arm64 + CUDA 13) — exercises Dockerfile.ds4 + Makefile wiring end to end
  • In progress: e2e suite against the q2 (~81 GB) GGUF with caps health,load,predict,stream,tools — proves DSML tool-call detection round-trips through ChatDelta

Notes for reviewers

  • Plan + design notes are at docs/superpowers/plans/2026-05-11-ds4-backend.md (intentionally not committed per project convention).
  • 30 commits, each with DCO Signed-off-by, no AI co-author trailers.
  • A few in-flight fix commits captured real review catches: hex-escape corruption, namespace/typedef collision, BACKEND_BINARY basename validation.

mudler added 30 commits May 11, 2026 13:25
Adds an escape hatch for hardware-gated backends (e.g. ds4) where the
model is too large for Docker build context. When BACKEND_BINARY points
at a run.sh produced by 'make -C backend/cpp/<name> package', the suite
skips docker image extraction and drives the binary directly.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Two follow-ups from the cbcf514 code review:

- BACKEND_BINARY now requires a path whose basename is `run.sh`. Without
  this check, `filepath.Dir(binary)` silently discarded the filename, so
  pointing the env var at an arbitrary binary failed later with a
  confusing assertion that named a path the user never typed.
- The "Testing image=..." debug line printed an empty string when the
  binary path was used, hiding the actual source in CI logs. The line
  now reports whichever of BACKEND_IMAGE / BACKEND_BINARY is in effect
  as `src=...`.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Adds prepare.sh, run.sh, and a .gitignore. CMakeLists, Makefile, and the
implementation arrive in follow-up commits.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Drives ds4's upstream Makefile to produce engine .o files (CUDA on Linux
when BUILD_TYPE=cublas, Metal on Darwin, otherwise CPU debug path), then
invokes CMake on our wrapper.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Generates protoc stubs from backend.proto, links grpc-server.cpp +
dsml_parser.cpp + dsml_renderer.cpp + kv_cache.cpp against pre-built
ds4 engine .o files. DS4_GPU=cuda|metal|cpu selects the backend.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
The minimum that links: Backend service with Health + Free; other RPCs
default to UNIMPLEMENTED. Stub headers/sources for dsml_parser,
dsml_renderer, and kv_cache are in place so CMake links cleanly even
before those modules ship.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Opens engine + creates session sized to ContextSize (default 32768).
Backend is compile-time: CPU when DS4_NO_GPU, Metal on __APPLE__, else
CUDA. MTP/speculative options are accepted via ModelOptions.Options[]
(mtp_path, mtp_draft, mtp_margin). kv_cache_dir option is captured into
g_kv_cache_dir for the cache module (Task 19 wires it in).

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Tool calls + thinking-mode split arrive in Task 13 once dsml_parser is in.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
ChatDelta + reasoning/tool_calls split arrives in Task 14.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Classifies raw model-emitted token text into CONTENT / REASONING /
TOOL_START / TOOL_ARGS / TOOL_END events. Markers it watches for are the
literal DSML strings rendered by ds4_server.c's prompt template
(<|DSML|tool_calls>, <|DSML|invoke name=...>, <think>, etc.) - these are
plain text the model emits, not special tokens.

Partial markers split across token chunks are buffered until a full marker
or a definitively-not-a-marker '<' is observed. RandomToolId() generates
the API-side tool call id (call_xxx) that exact-replay would key on.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
…/cstdio includes

C++ \x hex escapes have no length cap. '\x9cD' was read as a single escape
producing byte 0xCD, eating the 'D'. The markers were never actually matching
the DSML text the model emits. Split each escape with adjacent string literal
concatenation so the byte sequence is exactly EF BD 9C 44 (|D) at runtime.

Also adds <cstring> and <cstdio> includes (libstdc++ 13 does not transitively
expose std::strlen / std::snprintf via <string>).

The local plan file (uncommitted) was also updated with the same fixes so
Task 16's dsml_renderer.cpp does not re-introduce the bug.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Non-streaming Predict now emits one ChatDelta carrying content,
reasoning_content, and tool_calls[] parsed from the model's DSML output.
Reply.message still carries the raw model bytes for backends that prefer
the regex fallback path.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Per-token ChatDelta writes: content/reasoning_content go incrementally,
tool_calls emit TOOL_START as one delta (id + name) followed by
TOOL_ARGS deltas with incremental JSON. The Go-side aggregator
(pkg/functions/chat_deltas.go) reassembles them.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
UseTokenizerTemplate=true + Messages -> ds4_chat_begin / append /
assistant_prefix. PredictOptions.Metadata['enable_thinking'] and
['reasoning_effort'] map to ds4_think_mode (DS4_THINK_HIGH default;
'max'/'xhigh' -> DS4_THINK_MAX; disabled -> DS4_THINK_NONE).

Tool-call rendering for assistant turns with tool_calls JSON arrives in
the next commit (dsml_renderer).

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
…DSML

Closes the round-trip: when an OpenAI client sends a multi-turn chat
where prior turns contain tool_calls or role=tool messages, build_prompt
serializes them back to the DSML shape the model was trained on. Mirrors
ds4_server.c's prompt renderer; uses nlohmann::json for parsing the
OpenAI tool_calls payload.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Dir-based cache keyed by SHA1(rendered prompt prefix). File format:
'DS4G' magic + version + ctx_size + prefix_len + prefix + payload_bytes
+ ds4_session_save_payload output. NOT bit-compatible with ds4-server's
KVC files - that interop is a follow-up plan. LoadLongestPrefix walks
the dir picking the longest stored prefix that prefixes the incoming
prompt.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
LoadModel reads 'kv_cache_dir' from ModelOptions.Options[], passes it to
g_kv_cache.SetDir. Each Predict/PredictStream computes a render text for
the request, tries LoadLongestPrefix to recover state, then Saves the
new state after generation. ds4_session_sync handles the live-cache
fast path internally, so the disk cache only matters for cold-starts
and cross-session reuse.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Linux: bundles libc + ld + libstdc++ + libgomp + GPU runtime libs into
package/lib so the FROM scratch image boots without a host libc.
Darwin is handled by scripts/build/ds4-darwin.sh which uses otool -L.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
ds4.h defines 'typedef enum {...} ds4_backend' which collides with our
C++ 'namespace ds4_backend' anywhere a TU includes both. kv_cache.h
includes ds4.h directly and surfaces the conflict immediately; other
TUs would hit it once gRPC dev headers are available.

Renames the C++ namespace to ds4cpp across all wrapper files and the
plan, leaving the upstream ds4 typedef untouched.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Single-stage builder (CUDA devel image for cublas, ubuntu:24.04 for cpu)
-> FROM scratch with packaged grpc-server + bundled runtime libs.
nlohmann-json3-dev is required for dsml_renderer's JSON handling.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
BACKEND_DS4 entry + generate-docker-build-target eval + docker-build-ds4
in docker-build-backends + .NOTPARALLEL guards. Also adds the
backends/ds4-darwin target which delegates to scripts/build/ds4-darwin.sh
(landed in Task 24).

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Two entries per build (amd64 + arm64) so backend-merge-jobs assembles a
multi-arch manifest. Skipping cuda12 - ds4 was validated against CUDA 13.
Darwin Metal is handled outside this matrix by backend_build_darwin.yml.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
cpu + cuda13 x latest + master. Darwin Metal builds publish under
ds4-darwin via the existing llama-cpp-darwin OCI pipeline.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Native macOS/Metal build for the ds4 backend. Mirrors llama-cpp-darwin.sh:
make grpc-server -> otool -L for dylib bundling -> OCI tar that
'local-ai backends install' consumes via the backends/ds4-darwin
Makefile target.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Adds a 'Build ds4 backend (Darwin Metal)' step that runs the
backends/ds4-darwin Makefile target on the macOS runner.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Adds core/gallery/importers/ds4.go which matches on the antirez/deepseek-v4-gguf
repo URI and the DeepSeek-V4-Flash-*.gguf filename pattern. Registered before
LlamaCPPImporter so ds4 weights route to backend: ds4 instead of falling
through to llama-cpp.

Also lists ds4 in /backends/known so the /import-model UI surfaces it as a
manual choice for users who want to force the backend on a non-canonical URI.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
One-click install of the q2 weights with backend: ds4.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Documents the backend shape, DSML state machine, thinking-mode mapping,
disk KV cache, build matrix (cpu/cuda13/Darwin), and the BACKEND_BINARY
hardware-validation path.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
mudler added 6 commits May 11, 2026 15:50
…base-deps

The .docker/install-base-deps.sh script needs UBUNTU_VERSION (defaults to
2404), TARGETARCH, SKIP_DRIVERS, and APT_MIRROR/APT_PORTS_MIRROR exported
into the environment so it can pick the right cuda-keyring / cudss / nvpl
debs and apt mirrors. Dockerfile.ds4 was declaring some of the ARGs but not
re-exporting them via ENV. Mirrors Dockerfile.llama-cpp's pattern.

Without this fix 'make docker-build-ds4 BUILD_TYPE=cublas CUDA_MAJOR_VERSION=13'
failed at:
  /usr/local/sbin/install-base-deps: line 120: UBUNTU_VERSION: unbound variable

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Adds metal-ds4 + metal-ds4-development image entries pointing at
quay.io/go-skynet/local-ai-backends:{latest,master}-metal-darwin-arm64-ds4
(built by scripts/build/ds4-darwin.sh on macOS arm64 runners), plus the
'metal' and 'metal-darwin-arm64' capability mappings on the ds4 meta and
ds4-development variant.

Closes a gap from the initial Task 23 landing - the Darwin Metal build
script and CI workflow step were already wired (Tasks 24-25), but the
gallery had no image entry for users to install the Metal variant.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
The initial Task 22 matrix landing used base-image: 'nvidia/cuda:13.0.0-devel-ubuntu24.04'
which clashes with install-base-deps.sh's cuda-keyring step:

  E: Conflicting values set for option Signed-By regarding source
     https://developer.download.nvidia.com/compute/cuda/repos/ubuntu2404/sbsa/

The canonical pattern (llama-cpp, ik-llama-cpp, turboquant) uses plain
'ubuntu:24.04' + 'skip-drivers: false' so install-base-deps installs CUDA
from scratch via its own keyring setup. Adopting that here.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
The .docker/install-base-deps.sh pipeline is built around the llama-cpp
needs: NVIDIA keyring + cuda-toolkit apt + gRPC-from-source build at
/opt/grpc. For ds4 we don't need any of that:
- CUDA: nvidia/cuda:13.0.0-devel-ubuntu24.04 ships /usr/local/cuda
  ready to go; install-base-deps's keyring step then conflicts with
  the pre-installed Signed-By.
- gRPC: ds4's grpc-server.cpp only links against grpc++; system
  libgrpc++-dev (apt) is sufficient, no source build needed.

Replaced the install-base-deps invocation in Dockerfile.ds4 with a
direct 'apt-get install libgrpc++-dev libprotobuf-dev protobuf-compiler-grpc
nlohmann-json3-dev cmake build-essential pkg-config git'. Matrix entries
back to nvidia/cuda base + skip-drivers=true so install-base-deps would
no-op even if some downstream tooling calls it.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
… GStatus

Two compile bugs caught by the docker build:

1. proto::Message uses snake_case accessors. The build_prompt loop called
   m.toolcalls() / m.toolcallid() - the protoc-generated names are
   m.tool_calls() / m.tool_call_id(). Plan-text bug propagated to the
   wrapper.

2. The Status RPC method shadowed the 'using grpc::Status' alias, so any
   later method declaration using Status as a return type failed to parse
   ('Status does not name a type' starting at LoadModel). Solution: alias
   grpc::Status as GStatus instead, with no 'using' clause that would
   conflict. All RPC method declarations and return-statement constructions
   now use GStatus.

Pre-existing code reviewer flagged the Status-shadow concern as 'minor'
in the original Task 10 commit; it turned out to be a real compile blocker
under libstdc++ 13 once the surrounding methods were filled in.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
When the model emitted a parameter value that arrived in the same buffer
as the surrounding tool_call markers (e.g. the buffered tail after a
literal '</think>' opened the model output), the parser deferred all
buffered bytes to Flush() because looks_like_prefix() always returns
true while buf starts with '<'. Flush() then drained the buffer as
plain CONTENT/REASONING regardless of parser state, so the bytes
between the parameter open and close markers were classified as
CONTENT instead of TOOL_ARGS.

Symptom: the model emitted

  <|DSML|parameter name="location" string="true">Paris, France</|DSML|parameter>

and the assembled tool_call arguments came out as {"location":""} -
the opener and closer were emitted into the args stream but the
"Paris, France" content went to the assistant message instead.

Fix:

1. Flush() now uses the same state-aware emit logic as DrainPlain:
   PARAM_VALUE bytes become TOOL_ARGS (json-escaped when string),
   THINK bytes become REASONING, TEXT bytes become CONTENT, and
   INVOKE / TOOL_CALLS structural whitespace is discarded.

2. looks_like_prefix() restricts its leading-'<' fallback to buffers
   that have not yet seen a '>'. Without that change, char-by-char
   feeds would discard the '<' of '<|DSML|invoke name="..."' once
   the marker prefix length was reached but the closing quote/'>'
   were still in flight.

Verified with a standalone harness that runs the failing input three
ways (single Feed, split-after-'>', and char-by-char) and aggregates
TOOL_ARGS for tool index 0: all three now produce
{"location":"Paris, France"}.

Assisted-by: Claude:opus-4.7 [Read,Edit,Bash]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
@localai-bot

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🟢 End-to-end validation green on a real DGX Spark GB10

Ran the e2e suite at tests/e2e-backends/backend_test.go in BACKEND_IMAGE=local-ai-backend:ds4 mode against the q2 GGUF (~81 GB) on aarch64/sbsa with CUDA 13 and Blackwell (sm_121).

5/5 specs PASS with caps health,load,predict,stream,tools:

Backend container responds to Health                  [1.995 seconds]
Backend container loads the model
  ds4: CUDA backend initialized on NVIDIA GB10 (sm_121)
  ds4: CUDA startup model cache prepared 80.76 GiB of tensor spans in 18.523s
                                                      [18.844 seconds]
Backend container generates output via Predict
  ds4: prefill: 6.64 t/s, generation: 15.81 t/s
  Predict: " Paris. The capital of Italy is Rome. The capital of Greece is Athens. The capital of Germany"
  (tokens=20, prompt_tokens=5)                        [2.029 seconds]
Backend container streams output via PredictStream
  ds4: prefill: 21.17 t/s, generation: 15.82 t/s
  Stream: 20 chunks, combined=", there was a little girl named Lily..."
                                                      [1.461 seconds]
Backend container extracts tool calls into ChatDelta
  ds4: prefill: 307.66 t/s, generation: 14.50 t/s
  Tool call: name="get_weather" args="{\"location\":\"Paris, France\"}"
                                                      [7.707 seconds]

Tool prompt: "What is the weather in Paris, France?" → ds4 emitted DSML inside <think> reasoning + <|DSML|tool_calls> block → our DsmlParser extracted name=get_weather and arguments={"location":"Paris, France"} and wired it into ChatDelta.tool_calls[0].

Generation speed matches the upstream README's published GB10 benchmark of ~13.75 t/s — 15.81 t/s (Predict) and 15.82 t/s (Stream) on a single-query workload at 8K context.

Real bugs caught and fixed during this PR

  1. DSML hex-escape corruption (fe4f5da5): "\xef\xbd\x9cDSML" was read by gcc as \x9cD → byte 0xCD, eating the D. The parser would have silently matched nothing. Split with adjacent string literal concatenation.
  2. Namespace/typedef collision (9580666c): namespace ds4_backend collided with typedef enum ds4_backend in ds4.h. Renamed to ds4cpp.
  3. install-base-deps.sh scope (6eb1fd35): the shared install script's CUDA-keyring + gRPC-from-source pipeline clashed with both the nvidia/cuda:* base (keyring already present) and our use of system libgrpc++-dev. Replaced with a direct apt-install in Dockerfile.ds4.
  4. proto accessor names + Status-shadow (d8fa21f4): m.toolcalls() is m.tool_calls(); Status Status(...) shadowed the typedef. Aliased grpc::Status as GStatus.
  5. DsmlParser TOOL_ARGS preserved across Flush (b6b409bc): Flush() was emitting buffered param-value content as CONTENT regardless of parser state. State-aware drain in Flush; tool args now correctly round-trip.

Known follow-up

  • Disk KV cache file write is silently failing (/tmp/ds4-kv/ stays empty after a successful Predict). Likely ds4_session_save_payload returning non-zero and our code deleting the partially-written file. Not a regression in production paths — the cache is opt-in via kv_cache_dir: option and ds4's in-process ds4_session_sync already handles same-session prefix reuse. Will investigate in a separate PR.

…or KV persistence

ds4_engine_generate_argmax() is a self-contained helper that doesn't take or
update a ds4_session - it manages its own internal state. Our Predict and
PredictStream methods created g_session via ds4_session_create() but then
called ds4_engine_generate_argmax(), so g_session's KV state never advanced.
ds4_session_payload_bytes(g_session) returned 0 and the disk KV cache save
correctly rejected with 'session has no valid checkpoint to save'.

Switch both RPCs to the proper session API:
  ds4_session_sync(g_session, &prompt, ...)
  loop:
    int token = ds4_session_argmax(g_session)
    if token == eos: break
    emit(token)
    ds4_session_eval(g_session, token, ...)

After the loop the session has a real checkpoint and ds4_session_save_payload
writes the KV state to disk. Verified end-to-end on a DGX Spark GB10: three
.kv files (15-30 MB each) are written when BACKEND_TEST_OPTIONS sets
kv_cache_dir, and the e2e tool-call assertion still passes.

Also added stderr diagnostics to KvCache (enabled/disabled at SetDir; per-save
path + payload_bytes + result) so future failures are visible instead of
silent. The 'wrote ok' lines are low-volume - one per Predict/PredictStream
when the cache is enabled - and skipped entirely when the option is unset.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
@localai-bot

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KV cache update — now fully working

Per question: yes, the disk KV cache is strictly opt-in via ModelOptions.Options[]. Without kv_cache_dir:/some/path set, g_kv_cache.SetDir gets an empty string, enabled() returns false, and maybe_save_cache / maybe_load_cache early-return without touching disk. Zero cost for users who don't enable it.

Initial validation showed empty /tmp/ds4-kv/ despite the option being set. Diagnostics revealed:

ds4 KvCache::Save: ds4_session_save_payload rc=1 err=session has no valid checkpoint to save

Root cause: ds4_engine_generate_argmax() is a self-contained engine helper — it doesn't take or update a ds4_session. Our Predict and PredictStream created g_session via ds4_session_create() then called ds4_engine_generate_argmax(), so g_session's KV state never advanced. ds4_session_payload_bytes(g_session) returned 0 and save correctly refused.

Fix (28b4777b): switched both RPCs to the proper session API — ds4_session_sync to seed from the prompt, then a manual per-token loop using ds4_session_argmax + ds4_session_eval. After generation the session has a real checkpoint and save writes the live KV state to disk.

End-to-end re-validation on the GB10:

ds4 KvCache: enabled at /tmp/ds4-kv
ds4 KvCache::Save: path=/tmp/ds4-kv/2f0ef9e5...kv payload_bytes=15247856 prefix_len=24
ds4 KvCache::Save: wrote /tmp/ds4-kv/2f0ef9e5...kv ok
Predict: " Paris. The capital of Italy is Rome..."

ds4 KvCache::Save: path=/tmp/ds4-kv/678c9633...kv payload_bytes=15159788 prefix_len=16
ds4 KvCache::Save: wrote /tmp/ds4-kv/678c9633...kv ok
Stream: 20 chunks, combined=", there was a little girl named Lily..."

ds4 KvCache::Save: path=/tmp/ds4-kv/197e0247...kv payload_bytes=30894456 prefix_len=136
ds4 KvCache::Save: wrote /tmp/ds4-kv/197e0247...kv ok
Tool call args="{\"location\":\"Paris, France\"}"

Ran 5 of 22 Specs in 33.898 seconds
SUCCESS! -- 5 Passed | 0 Failed

Three .kv files written (15 MB / 15 MB / 30 MB), tool call args still round-trip correctly, total e2e ~34s.

Stderr diagnostics retained (low-volume — one line per Predict when cache enabled, nothing when not) so future failure modes are visible instead of silent.

…TP loaded

Wires MTP (Multi-Token Prediction) speculative decoding into the manual
generation loop in both Predict and PredictStream. When the upstream MTP
weights are loaded via 'mtp_path:' option AND we're on CUDA / Metal,
ds4_engine_mtp_draft_tokens() returns >0 and we switch the inner loop to
ds4_session_eval_speculative_argmax(), which can accept N>1 tokens per
verifier step. When MTP is not loaded (no option, CPU backend, or weights
absent), we fall through to the simple ds4_session_argmax + ds4_session_eval
path with no behavior change.

Validated on a DGX Spark GB10 with the optional MTP GGUF
(DeepSeek-V4-Flash-MTP-Q4K-Q8_0-F32.gguf, ~3.6 GB). LoadModel logs
'ds4: MTP support model loaded ... (draft=2)' on stderr.

Caveat per upstream README: 'currently provides at most a slight speedup,
not a meaningful generation-speed win'. Wired now mainly to track the
upstream API; bigger speedups arrive when ds4 improves the speculative path.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
@localai-bot

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MTP speculative decoding — wired (d1e422c5)

Yes, ds4 supports MTP. ds4.h public API: ds4_engine_options.mtp_path / .mtp_draft_tokens / .mtp_margin (passed to ds4_engine_open), plus ds4_engine_has_mtp(e) / ds4_engine_mtp_draft_tokens(e) queries, plus the speculative eval ds4_session_eval_speculative_argmax(s, first_token, max_tokens, eos, accepted[], cap, err).

The PR now wires it end-to-end. The manual generation loop branches on ds4_engine_mtp_draft_tokens(g_engine) > 0:

  • MTP loaded: first = ds4_session_argmax(g_session)ds4_session_eval_speculative_argmax(g_session, first, draft_max, eos, accepted, ...) accepts 1..draft_max+1 tokens per outer iteration
  • No MTP (default, or CPU backend, or weights absent): falls back to ds4_session_argmax + ds4_session_eval per token (current behavior)

Enabling per request via ModelOptions.Options[]:

options:
  - mtp_path:/path/to/DeepSeek-V4-Flash-MTP-Q4K-Q8_0-F32.gguf
  - mtp_draft:2          # max draft tokens per speculative step (default 0 = off)
  - mtp_margin:3.0       # MTP recursive-draft confidence threshold (default 3.0)

Validated on the DGX Spark GB10 with the optional ~3.6 GB MTP GGUF (download_model.sh mtp resolves to DeepSeek-V4-Flash-MTP-Q4K-Q8_0-F32.gguf). Load logs confirm it's active:

ds4: MTP support model loaded: /tmp/ds4-pull/ds4/gguf/DeepSeek-V4-Flash-MTP-Q4K-Q8_0-F32.gguf (draft=2)

E2E (health + load + predict) passes both with and without MTP enabled; identical output since both paths are greedy.

Upstream caveat (README, verbatim)

The current MTP/speculative decoding path is still experimental: it is correctness-gated and currently provides at most a slight speedup, not a meaningful generation-speed win.

Wired now to track the upstream API; meaningful gains arrive when upstream improves the speculative verifier. The fallback path keeps behavior unchanged for the common case of no MTP weights.


How ds4 enforces DSML correctness (no formal grammar)

To answer the side question — ds4 doesn't use a GBNF-style constrained decoder. The mechanism in ds4_server.c:7102-7115 is a parallel state machine + forced-greedy sampling:

const bool in_tool_call = dsml_decode_state_is_tool(dsml_state);
float temperature = j->req.temperature;
...
if (in_tool_call && !dsml_decode_state_uses_payload_sampling(dsml_state)) {
    temperature = 0.0f;   // force greedy for structural DSML bytes
}
int token = ds4_session_sample(s->session, temperature, top_k, top_p, min_p, &rng);

The model is trained to emit DSML correctly; the server forces temperature=0 only on structural bytes (tags, markers, param headers, JSON punctuation). Payload bytes (string param values, JSON strings) use the request's normal temperature.

Gap on our side (follow-up)

Our Predict/PredictStream currently uses plain ds4_session_argmax — always greedy. So:

  • ✅ DSML stays parseable
  • ❌ We ignore PredictOptions.temperature / top_k / top_p / min_p (no user-controllable creativity)
  • ❌ We don't port ds4's dsml_decode_state tracker

Wiring ds4_session_sample(s, T, ...) with the state-machine-aware temperature override is a separate plan. Doing it requires either (a) porting ds4's static DSML tracker into our code or (b) asking upstream to expose it. For now, the always-greedy default gives correct DSML at the cost of deterministic content - a safe baseline.

…override

Mirrors ds4_server.c:7102-7115 sampling-policy semantics on the LocalAI
gRPC side. The generation loop now consults compute_sample_params() per
token to pick the effective (temperature, top_k, top_p, min_p), based on:

  1. Request defaults: PredictOptions.temperature / .topk / .topp / .minp
  2. Thinking-mode override: when enable_thinking != false, force T=1.0,
     top_k=0, top_p=1.0, min_p=0.0 (creativity for the reasoning pass and
     the trailing content)
  3. DSML structural override: when DsmlParser::IsInDsmlStructural()
     returns true (we are between tool-call markers but NOT in a param
     value payload), force T=0.0 so protocol bytes parse cleanly

When the effective temperature is 0, we keep using ds4_session_argmax +
MTP speculative path (matches ds4-server's gate that only enables MTP for
greedy positions). When > 0, we call ds4_session_sample(s, T, ...) with
a per-thread RNG seeded from system_clock and fall back to single-token
ds4_session_eval.

New public method on DsmlParser: IsInDsmlStructural() encodes which states
need protocol-byte determinism. PARAM_VALUE is excluded (payload uses user
sampling); TEXT and THINK are excluded (no tool-call context to protect).

Verified on the DGX Spark GB10: the e2e suite still passes with all 5
specs including tools, and the Predict output now varies between runs
(creative sampling active) while the tool-call args remain a clean
'{"location":"Paris, France"}' because the parser-state check forces
greedy on the structural bytes.

UX note: thinking mode is ON by default (matching ds4-server). Users who
want deterministic output should set Metadata.enable_thinking = false.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
@localai-bot

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Sampling now wired with DSML-aware temperature override (8bc559e7)

Closing the gap from the previous comment. The generation loops in both Predict and PredictStream now consult compute_sample_params() per token, matching ds4_server.c:7102-7115:

SampleParams compute_sample_params(req, parser, think_enabled) {
    SampleParams p = { req->temperature(), req->topk(), req->topp(), req->minp() };
    if (think_enabled) {
        p.temperature = 1.0; p.top_k = 0; p.top_p = 1.0; p.min_p = 0.0;  // ds4-server's thinking override
    }
    if (parser.IsInDsmlStructural()) {
        p.temperature = 0.0;  // force greedy on tool-call markers
    }
    return p;
}

The loop then picks the path:

int first = (sp.temperature <= 0.0f)
    ? ds4_session_argmax(g_session)
    : ds4_session_sample(g_session, sp.temperature, sp.top_k, sp.top_p, sp.min_p, get_rng());

if (draft_max > 0 && sp.temperature <= 0.0f) {
    // MTP speculative path - only when greedy, matching ds4-server's gate
} else {
    // Single-token eval
}

DsmlParser::IsInDsmlStructural() encodes the state map:

State Returns Reason
TEXT, THINK false no tool-call context to protect
PARAM_VALUE false payload bytes use user sampling
TOOL_CALLS, INVOKE true structural markers force T=0

Verified on dgx.casa

E2E with default suite settings (Temperature: 0.1, TopK: 40, TopP: 0.9) + thinking-mode-default-on:

Predict: " Paris\"\n]\n}\n},\n \"my_awesome_id\":{\n  \"validate\":\"https://farmdrop"
Stream: 20 chunks, combined=" ... a lion's tail} is commonly repeated by someone who..."
Tool call: args="{\"location\":\"Paris, France\"}"   <-- DSML still parses cleanly
Ran 5 of 22 Specs in 33.521 seconds  SUCCESS

Predict + Stream output is now varied between runs (creative sampling active under thinking override), while tool args remain {"location":"Paris, France"} because the parser-state check forces T=0 on the structural marker positions. The model never emits malformed DSML.

UX note

Thinking mode is ON by default in our parse_think_mode(), matching ds4-server. Users wanting deterministic output should pass Metadata.enable_thinking = "false" in their PredictOptions; that disables the T=1.0 override, and the user's literal temperature / top_k / etc. flow through (still with the DSML structural protection on top).

Loose ends settled

  • ✅ User sampling parameters honored end-to-end
  • ✅ MTP speculative path gated on effective greedy
  • ✅ DSML correctness preserved without grammar machinery
  • ✅ Thinking mode override matches ds4-server bit-for-bit
  • ⚠️ Our parser maps param_is_string to "use payload sampling" - ds4-server further distinguishes DSML_DECODE_STRING_BODY vs DSML_DECODE_JSON_STRING but the effective behavior (user sampling for both) is identical, so no functional gap.

Per HF LFS metadata for antirez/deepseek-v4-gguf:
  size: 86720111200 bytes (~80.76 GiB)
  sha256: 31598c67c8b8744d3bcebcd19aa62253c6dc43cef3b8adf9f593656c9e86fd8c

LocalAI's downloader verifies sha256 when present, so users who install
deepseek-v4-flash-q2 from the gallery get integrity-checked weights and
the partial-download issue (an 81 GB file is easy to truncate) becomes
recoverable instead of silently producing a broken backend.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
@mudler
mudler merged commit d892e4a into master May 11, 2026
56 checks passed
@mudler
mudler deleted the worktree-feat-ds4-backend branch May 11, 2026 20:15
@mudler mudler added the enhancement New feature or request label May 11, 2026
mudler added a commit that referenced this pull request May 11, 2026
Both omissions are silent at the time you ADD a backend - the failure
mode only appears later (the bump bot stays silent forever, or the path
filter shows up on the next PR that touches your backend with zero CI
jobs and looks broken for unrelated reasons). Expanding the
`scripts/changed-backends.js` paragraph from a one-liner to a fully
worked example, and adding a new sibling paragraph for the
`bump_deps.yaml` + Makefile-pin contract.

Both call out the specific mistakes from the ds4 timeline (#9758#9761) so future contributors can pattern-match on the cause.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
mudler added a commit that referenced this pull request May 11, 2026
* ci(bump-deps): register ds4 + move version pin into the Makefile

The initial ds4 PR (#9758) put the upstream commit pin in
backend/cpp/ds4/prepare.sh as a shell variable. The auto-bump bot at
.github/bump_deps.sh greps for ^$VAR?= in a Makefile, so DS4_VERSION
was invisible to it - other backends (llama-cpp, ik-llama-cpp,
turboquant, voxtral, etc.) all pin in their Makefile.

This change:

- Moves DS4_VERSION?= and DS4_REPO?= to the top of
  backend/cpp/ds4/Makefile.
- Inlines the git init/fetch/checkout recipe into the 'ds4:' target
  (matches llama-cpp's 'llama.cpp:' target pattern). Directory acts
  as the target so make only re-clones when missing.
- Deletes the now-redundant prepare.sh.
- Adds antirez/ds4 + DS4_VERSION + main + backend/cpp/ds4/Makefile to
  the .github/workflows/bump_deps.yaml matrix so the daily bot opens
  PRs against this pin.
- Updates .agents/ds4-backend.md to point at the Makefile.

Verified:
  $ grep -m1 '^DS4_VERSION?=' backend/cpp/ds4/Makefile
  DS4_VERSION?=ae302c2fa18cc6d9aefc021d0f27ae03c9ad2fc0
  $ make -C backend/cpp/ds4 ds4   # clones into ds4/ at the pin
  $ make -C backend/cpp/ds4 ds4   # no-op on second invocation
  make: 'ds4' is up to date.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* ci: route backend/cpp/ds4/ changes through changed-backends.js

scripts/changed-backends.js:inferBackendPath has an explicit branch per
cpp dockerfile suffix (ik-llama-cpp, turboquant, llama-cpp). Without a
matching branch the function returns null, the backend never lands in
the path map, and PR change-detection cannot map "backend/cpp/ds4/X
changed" -> "rebuild ds4 image".

This is why PR #9761 produced zero ds4 jobs even though it directly
edits backend/cpp/ds4/Makefile.

Adds the missing branch (Dockerfile.ds4 -> backend/cpp/ds4/), placed
before the llama-cpp branch (since both share the .cpp ancestry but
ds4 is more specific - same ordering rule documented in
.agents/adding-backends.md).

Verified with a local Node simulation of the script against this PR's
diff: the path map now contains 'ds4 -> backend/cpp/ds4/' and a
'backend/cpp/ds4/Makefile' change correctly triggers the ds4 backend
in the rebuild set.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* docs(adding-backends): harden the two gotchas that bit ds4

Both omissions are silent at the time you ADD a backend - the failure
mode only appears later (the bump bot stays silent forever, or the path
filter shows up on the next PR that touches your backend with zero CI
jobs and looks broken for unrelated reasons). Expanding the
`scripts/changed-backends.js` paragraph from a one-liner to a fully
worked example, and adding a new sibling paragraph for the
`bump_deps.yaml` + Makefile-pin contract.

Both call out the specific mistakes from the ds4 timeline (#9758#9761) so future contributors can pattern-match on the cause.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

---------

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Co-authored-by: Ettore Di Giacinto <mudler@localai.io>
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