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LocalAI/.agents/ds4-backend.md
LocalAI [bot] 621c612b2d ci(bump-deps): register ds4 + move version pin into the Makefile (#9761)
* 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>
2026-05-11 22:46:02 +02:00

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# Working on the ds4 Backend
`antirez/ds4` is a single-model inference engine for DeepSeek V4 Flash.
LocalAI wraps the engine's C API (`ds4/ds4.h`) with a fresh C++ gRPC server at
`backend/cpp/ds4/` - NOT a fork of llama-cpp's grpc-server.cpp.
## Pin
`backend/cpp/ds4/Makefile` pins `DS4_VERSION?=<sha>` at the top. The `ds4`
target in the Makefile clones `antirez/ds4` at that commit (mirroring the
llama-cpp / ik-llama-cpp / turboquant pattern). The bump-deps bot
(`.github/workflows/bump_deps.yaml`) finds this pin via grep and opens a
daily PR to update it. To bump manually: edit the `DS4_VERSION?=` line,
then `make purge && make` (or rely on CI's clean build).
## Wire shape
| RPC | Implementation |
|---|---|
| Health, Free, Status | Trivial; no engine dependency for Health |
| LoadModel | `ds4_engine_open` + `ds4_session_create`; backend is compile-time (DS4_NO_GPU → CPU, __APPLE__ → Metal, otherwise CUDA) |
| TokenizeString | `ds4_tokenize_text` |
| Predict | `ds4_engine_generate_argmax` + `DsmlParser` → one ChatDelta with content / reasoning_content / tool_calls[] |
| PredictStream | Same, per-token ChatDelta writes |
## DSML
ds4 emits tool calls as literal text markers (`<DSMLtool_calls>` etc.) -
NOT special tokens. `dsml_parser.{h,cpp}` is our streaming state machine that
classifies token bytes into CONTENT / REASONING / TOOL_START / TOOL_ARGS / TOOL_END
events. `dsml_renderer.{h,cpp}` does the prompt direction: turns
OpenAI tool_calls + role=tool messages back into DSML for the next turn.
## Thinking modes
`PredictOptions.Metadata["enable_thinking"]` gates thinking on/off (default ON).
`["reasoning_effort"] == "max" | "xhigh"` selects `DS4_THINK_MAX`; anything else
maps to `DS4_THINK_HIGH`. We pass the chosen mode to `ds4_chat_append_assistant_prefix`.
## Disk KV cache
`kv_cache.{h,cpp}` implements an SHA1-keyed file cache using ds4's public
`ds4_session_save_payload` / `ds4_session_load_payload` API. Enable per request
via `ModelOptions.Options[] = "kv_cache_dir:/some/path"`. Format is **our own** -
NOT bit-compatible with ds4-server's KVC files (interop is a follow-up plan).
## Build matrix
| Build | Where | Notes |
|---|---|---|
| `cpu-ds4` (amd64 + arm64) | Linux GHA | ds4 considers CPU debug-only; useful only for wiring tests |
| `cuda13-ds4` (amd64 + arm64) | Linux GHA + DGX Spark validation | Primary production path on Linux |
| `ds4-darwin` (arm64) | macOS GHA runners | Metal; uses `scripts/build/ds4-darwin.sh` like llama-cpp-darwin |
cuda12 is intentionally omitted. ROCm / Vulkan / SYCL are not applicable.
## Hardware-gated validation
`tests/e2e-backends/backend_test.go` in `BACKEND_BINARY` mode:
```
BACKEND_BINARY=$(pwd)/backend/cpp/ds4/package/run.sh \
BACKEND_TEST_MODEL_FILE=/path/to/ds4flash.gguf \
BACKEND_TEST_CAPS=health,load,predict,stream,tools \
BACKEND_TEST_TOOL_PROMPT="What's the weather in Paris?" \
go test -count=1 -timeout=30m -v ./tests/e2e-backends/...
```
CI does not load the model; the suite is opt-in via env vars.
## Importer
`core/gallery/importers/ds4.go` (`DS4Importer`) auto-detects ds4 weights by
matching the `antirez/deepseek-v4-gguf` repo URI or the
`DeepSeek-V4-Flash-*.gguf` filename pattern. **Registered BEFORE
`LlamaCPPImporter`** in `defaultImporters` - both match `.gguf` but ds4 is more
specific, and first-match-wins. The importer emits `backend: ds4`, uses
`ds4flash.gguf` as the local filename (matches ds4's own CLI default), and
disables the Go-side automatic tool-parsing fallback (the C++ backend emits
ChatDelta.tool_calls natively via `DsmlParser`).
ds4 is also listed in `core/http/endpoints/localai/backend.go`'s pref-only
slice so the `/import-model` UI surfaces it as a manual choice for users who
want to force the backend on a non-canonical URI.