fix(kokoro): add CPU backend fallback (#11161)

Publish the existing Kokoro CPU profile for amd64 and arm64 and use it as the default gallery capability so Vulkan-only and CPU hosts can install the backend.

Assisted-by: Codex:gpt-5

Co-authored-by: localai-org-maint-bot <306269227+localai-org-maint-bot@users.noreply.github.com>

.github/backend-matrix.yml

@@ -66,6 +66,34 @@ include:
     dockerfile: "./backend/Dockerfile.python"
     context: "./"
     ubuntu-version: '2404'
+  - build-type: ''
+    cuda-major-version: ""
+    cuda-minor-version: ""
+    platforms: 'linux/amd64'
+    platform-tag: 'amd64'
+    tag-latest: 'auto'
+    tag-suffix: '-cpu-kokoro'
+    runs-on: 'ubuntu-latest'
+    base-image: "ubuntu:24.04"
+    skip-drivers: 'true'
+    backend: "kokoro"
+    dockerfile: "./backend/Dockerfile.python"
+    context: "./"
+    ubuntu-version: '2404'
+  - build-type: ''
+    cuda-major-version: ""
+    cuda-minor-version: ""
+    platforms: 'linux/arm64'
+    platform-tag: 'arm64'
+    tag-latest: 'auto'
+    tag-suffix: '-cpu-kokoro'
+    runs-on: 'ubuntu-24.04-arm'
+    base-image: "ubuntu:24.04"
+    skip-drivers: 'true'
+    backend: "kokoro"
+    dockerfile: "./backend/Dockerfile.python"
+    context: "./"
+    ubuntu-version: '2404'
   - build-type: ''
     cuda-major-version: ""
     cuda-minor-version: ""

backend/index.yaml

@@ -1455,6 +1455,7 @@
   alias: "kokoro"
   name: "kokoro"
   capabilities:
+    default: "cpu-kokoro"
     nvidia: "cuda12-kokoro"
     intel: "intel-kokoro"
     amd: "rocm-kokoro"
@@ -5186,11 +5187,22 @@
 - !!merge <<: *kokoro
   name: "kokoro-development"
   capabilities:
+    default: "cpu-kokoro-development"
     nvidia: "cuda12-kokoro-development"
     intel: "intel-kokoro-development"
     amd: "rocm-kokoro-development"
     nvidia-l4t: "nvidia-l4t-kokoro-development"
     metal: "metal-kokoro-development"
+- !!merge <<: *kokoro
+  name: "cpu-kokoro"
+  uri: "quay.io/go-skynet/local-ai-backends:latest-cpu-kokoro"
+  mirrors:
+    - localai/localai-backends:latest-cpu-kokoro
+- !!merge <<: *kokoro
+  name: "cpu-kokoro-development"
+  uri: "quay.io/go-skynet/local-ai-backends:master-cpu-kokoro"
+  mirrors:
+    - localai/localai-backends:master-cpu-kokoro
 - !!merge <<: *kokoro
   name: "cuda12-kokoro-development"
   uri: "quay.io/go-skynet/local-ai-backends:master-gpu-nvidia-cuda-12-kokoro"

core/gallery/backends_test.go

@@ -32,6 +32,42 @@ var _ = Describe("Runtime capability-based backend selection", func() {
 		os.RemoveAll(tempDir)
 	})
 
+	It("keeps the Kokoro CPU fallback installable from the backend gallery", func() {
+		backends, err := ReadConfigFile[[]*GalleryBackend](filepath.Join("..", "..", "backend", "index.yaml"))
+		Expect(err).NotTo(HaveOccurred())
+
+		byName := make(map[string]*GalleryBackend, len(*backends))
+		for _, backend := range *backends {
+			byName[backend.Name] = backend
+		}
+
+		Expect(byName).To(HaveKey("kokoro"))
+		Expect(byName["kokoro"].CapabilitiesMap).To(HaveKeyWithValue("default", "cpu-kokoro"))
+		Expect(byName).To(HaveKey("cpu-kokoro"))
+		Expect(byName["cpu-kokoro"].URI).To(Equal("quay.io/go-skynet/local-ai-backends:latest-cpu-kokoro"))
+
+		type matrixEntry struct {
+			Backend     string `yaml:"backend"`
+			Platforms   string `yaml:"platforms"`
+			PlatformTag string `yaml:"platform-tag"`
+			TagSuffix   string `yaml:"tag-suffix"`
+		}
+		type backendMatrix struct {
+			Include []matrixEntry `yaml:"include"`
+		}
+
+		matrix, err := ReadConfigFile[backendMatrix](filepath.Join("..", "..", ".github", "backend-matrix.yml"))
+		Expect(err).NotTo(HaveOccurred())
+
+		var cpuArchitectures []string
+		for _, entry := range matrix.Include {
+			if entry.Backend == "kokoro" && entry.TagSuffix == "-cpu-kokoro" {
+				cpuArchitectures = append(cpuArchitectures, entry.Platforms+"/"+entry.PlatformTag)
+			}
+		}
+		Expect(cpuArchitectures).To(ConsistOf("linux/amd64/amd64", "linux/arm64/arm64"))
+	})
+
 	It("ListSystemBackends prefers optimal alias candidate", func() {
 		// Arrange two installed backends sharing the same alias
 		must := func(err error) { Expect(err).NotTo(HaveOccurred()) }

docs/content/reference/compatibility-table.md

@@ -55,7 +55,7 @@ All backends listed here can be installed on demand from the [Backend Gallery]({
 |---------|-------------|-------------|
 | [piper](https://github.com/rhasspy/piper) | Fast neural TTS | CPU, Metal |
 | [Coqui TTS](https://github.com/idiap/coqui-ai-TTS) | TTS with 1100+ languages and voice cloning | CUDA 12, ROCm, Intel SYCL, Metal |
-| [Kokoro](https://huggingface.co/hexgrad/Kokoro-82M) | Lightweight TTS (82M params) | CUDA 12/13, ROCm, Intel SYCL, Metal, Jetson L4T |
+| [Kokoro](https://huggingface.co/hexgrad/Kokoro-82M) | Lightweight TTS (82M params) | CPU, CUDA 12/13, ROCm, Intel SYCL, Metal, Jetson L4T |
 | [Kokoros](https://huggingface.co/hexgrad/Kokoro-82M) | Pure Rust Kokoro TTS via ONNX | CPU |
 | [Chatterbox](https://github.com/resemble-ai/chatterbox) | Production-grade TTS with emotion control | CPU, CUDA 12/13, Metal, Jetson L4T |
 | [VibeVoice](https://github.com/microsoft/VibeVoice) | Real-time TTS with voice cloning | CPU, CUDA 12/13, ROCm, Intel SYCL, Metal, Jetson L4T |