fix(backends): darwin/metal support for supertonic (#10488)

The supertonic Go TTS backend dlopens ONNX Runtime, but its runtime and
packaging scripts were Linux-only: run.sh exported LD_LIBRARY_PATH, pointed
ONNXRUNTIME_LIB_PATH at libonnxruntime.so, and always tried the ld.so exec
path, while package.sh hard-failed on any non-Linux host. On macOS dyld has
no ld.so loader, uses DYLD_LIBRARY_PATH, and ONNX Runtime ships as a .dylib.

This applies the same purego .dylib/DYLD_LIBRARY_PATH fix that PR #10481
landed for 15 other ONNX/purego backends (sherpa-onnx, silero-vad, etc.) but
which omitted supertonic:

- run.sh: on darwin export DYLD_LIBRARY_PATH and point ONNXRUNTIME_LIB_PATH
  at libonnxruntime.dylib; guard the ld.so exec path to Linux only.
- package.sh: recognize Darwin instead of erroring out; the bundled .dylib is
  resolved via DYLD_LIBRARY_PATH, no glibc/ld.so to bundle.
- helper.go: platform-native default library extension (dylib on darwin) for
  the last-resort dlopen fallback.

It also wires the darwin CI build and gallery entries, resolving the
inconsistency where backend/index.yaml advertised metal for supertonic but no
includeDarwin matrix entry built the image:

- .github/backend-matrix.yml: add the -metal-darwin-arm64-supertonic Go entry.
- backend/index.yaml: declare metal capabilities and add the concrete
  metal-supertonic / metal-supertonic-development child entries.

The Makefile already detects Darwin/osx/arm64 and stages the per-OS ONNX
Runtime tarball, mirroring sherpa-onnx, so no Makefile change is required.


Assisted-by: Claude:opus-4.8 [Claude Code]

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

.github/backend-matrix.yml

@@ -4990,6 +4990,10 @@ includeDarwin:
     tag-suffix: "-metal-darwin-arm64-sherpa-onnx"
     build-type: "metal"
     lang: "go"
+  - backend: "supertonic"
+    tag-suffix: "-metal-darwin-arm64-supertonic"
+    build-type: "metal"
+    lang: "go"
   - backend: "local-store"
     tag-suffix: "-metal-darwin-arm64-local-store"
     build-type: "metal"

backend/go/supertonic/helper.go

@@ -16,6 +16,7 @@ import (
 	"os"
 	"path/filepath"
 	"regexp"
+	"runtime"
 	"strings"
 	"time"
 	"unicode"
@@ -943,7 +944,13 @@ func InitializeONNXRuntime() error {
 			}
 		}
 		if libPath == "" {
-			libPath = "/usr/local/lib/libonnxruntime.so"
+			// LocalAI: default to the platform-native shared library
+			// extension when nothing else is found (dyld vs ld.so).
+			if runtime.GOOS == "darwin" {
+				libPath = "/usr/local/lib/libonnxruntime.dylib"
+			} else {
+				libPath = "/usr/local/lib/libonnxruntime.so"
+			}
 		}
 	}
 	ort.SetSharedLibraryPath(libPath)

backend/go/supertonic/package.sh

@@ -32,6 +32,10 @@ elif [ -f "/lib/ld-linux-aarch64.so.1" ]; then
     cp -arfLv /lib/aarch64-linux-gnu/libdl.so.2 $CURDIR/package/lib/libdl.so.2
     cp -arfLv /lib/aarch64-linux-gnu/librt.so.1 $CURDIR/package/lib/librt.so.1
     cp -arfLv /lib/aarch64-linux-gnu/libpthread.so.0 $CURDIR/package/lib/libpthread.so.0
+elif [ $(uname -s) = "Darwin" ]; then
+    # macOS: dyld resolves the bundled .dylib via DYLD_LIBRARY_PATH (set in
+    # run.sh); there is no ld.so loader nor glibc to bundle.
+    echo "Detected Darwin"
 else
     echo "Error: Could not detect architecture"
     exit 1

backend/go/supertonic/run.sh

@@ -3,12 +3,19 @@ set -ex
 
 CURDIR=$(dirname "$(realpath $0)")
 
-export LD_LIBRARY_PATH=$CURDIR/lib:$LD_LIBRARY_PATH
-export ONNXRUNTIME_LIB_PATH=$CURDIR/lib/libonnxruntime.so
+if [ "$(uname)" = "Darwin" ]; then
+	# macOS uses dyld: there is no ld.so loader, and the search path env
+	# var is DYLD_LIBRARY_PATH. ONNX Runtime ships as a .dylib here.
+	export DYLD_LIBRARY_PATH=$CURDIR/lib:$DYLD_LIBRARY_PATH
+	export ONNXRUNTIME_LIB_PATH=$CURDIR/lib/libonnxruntime.dylib
+else
+	export LD_LIBRARY_PATH=$CURDIR/lib:$LD_LIBRARY_PATH
+	export ONNXRUNTIME_LIB_PATH=$CURDIR/lib/libonnxruntime.so
 
-if [ -f $CURDIR/lib/ld.so ]; then
-	echo "Using lib/ld.so"
-	exec $CURDIR/lib/ld.so $CURDIR/supertonic "$@"
+	if [ -f $CURDIR/lib/ld.so ]; then
+		echo "Using lib/ld.so"
+		exec $CURDIR/lib/ld.so $CURDIR/supertonic "$@"
+	fi
 fi
 
 exec $CURDIR/supertonic "$@"

backend/index.yaml

@@ -1569,6 +1569,7 @@
     - TTS
   capabilities:
     default: "cpu-supertonic"
+    metal: "metal-supertonic"
 - !!merge <<: *neutts
   name: "neutts-development"
   capabilities:
@@ -5484,6 +5485,7 @@
   name: "supertonic-development"
   capabilities:
     default: "cpu-supertonic-development"
+    metal: "metal-supertonic-development"
 - !!merge <<: *supertonic
   name: "cpu-supertonic"
   uri: "quay.io/go-skynet/local-ai-backends:latest-cpu-supertonic"
@@ -5494,3 +5496,13 @@
   uri: "quay.io/go-skynet/local-ai-backends:master-cpu-supertonic"
   mirrors:
     - localai/localai-backends:master-cpu-supertonic
+- !!merge <<: *supertonic
+  name: "metal-supertonic"
+  uri: "quay.io/go-skynet/local-ai-backends:latest-metal-darwin-arm64-supertonic"
+  mirrors:
+    - localai/localai-backends:latest-metal-darwin-arm64-supertonic
+- !!merge <<: *supertonic
+  name: "metal-supertonic-development"
+  uri: "quay.io/go-skynet/local-ai-backends:master-metal-darwin-arm64-supertonic"
+  mirrors:
+    - localai/localai-backends:master-metal-darwin-arm64-supertonic