diff --git a/Makefile b/Makefile
index 55b56b2d1..c44ee4557 100644
--- a/Makefile
+++ b/Makefile
@@ -726,7 +726,7 @@ LLAMASERVER_CXXFLAGS := -I./tools/mtmd
 
 
 #whisper objects
-whispercpp_default.o: otherarch/whispercpp/whisper_adapter.cpp
+whispercpp_default.o: otherarch/whispercpp/whisper_adapter.cpp otherarch/whispercpp/whisper.cpp kcpp_backend.h
 	$(CXX) $(CXXFLAGS) -c $< -o $@
 
 #tts objects
@@ -740,7 +740,7 @@ music_default.o: otherarch/acestep/music_adapter.cpp
 	$(CXX) $(CXXFLAGS) -c $< -o $@
 
 # idiotic "for easier compilation"
-GPTTYPE_ADAPTER = gpttype_adapter.cpp model_adapter.h otherarch/otherarch.h include/llama.h otherarch/llama_v2.cpp otherarch/llama_v3.cpp otherarch/gptj_v1.cpp otherarch/gptj_v2.cpp otherarch/gptj_v3.cpp otherarch/gpt2_v1.cpp otherarch/gpt2_v2.cpp otherarch/gpt2_v3.cpp otherarch/rwkv_v2.cpp otherarch/rwkv_v3.cpp otherarch/neox_v2.cpp otherarch/neox_v3.cpp otherarch/mpt_v3.cpp
+GPTTYPE_ADAPTER = gpttype_adapter.cpp kcpp_backend.h model_adapter.h otherarch/otherarch.h include/llama.h otherarch/llama_v2.cpp otherarch/llama_v3.cpp otherarch/gptj_v1.cpp otherarch/gptj_v2.cpp otherarch/gptj_v3.cpp otherarch/gpt2_v1.cpp otherarch/gpt2_v2.cpp otherarch/gpt2_v3.cpp otherarch/rwkv_v2.cpp otherarch/rwkv_v3.cpp otherarch/neox_v2.cpp otherarch/neox_v3.cpp otherarch/mpt_v3.cpp
 gpttype_adapter_default.o: $(GPTTYPE_ADAPTER)
 	$(CXX) $(CXXFLAGS) -c $< -o $@
 
@@ -771,7 +771,7 @@ fitparams: tools/fit-params/main.cpp tools/fit-params/fit-params.cpp common/arg.
 	$(CXX) $(CXXFLAGS) -DGGML_USE_VULKAN $(filter-out %.h,$^) -o $@ $(LDFLAGS)
 sdmain: $(OBJS_SDCOMMON) $(OBJS_SDMAIN) build-info.h ggml.o ggml-cpu.o ggml-ops.o ggml-vec.o ggml-binops.o ggml-unops.o llama.o chat.o llama-model.o console.o clip_default.o mtmd.o mtmd-helper.o mtmd-helper-gen.o mtmd-image.o ggml-backend.o ggml-backend-meta.o ggml-backend-reg_default.o ggml-repack.o $(OBJS_FULL) $(OBJS)
 	$(CXX) $(CXXFLAGS) $(filter-out %.h,$^) -o $@ $(LDFLAGS)
-whispermain: otherarch/whispercpp/main.cpp otherarch/whispercpp/whisper.cpp kcpp_backend.o build-info.h ggml.o ggml-cpu.o ggml-ops.o ggml-vec.o ggml-binops.o ggml-unops.o llama.o chat.o llama-model.o console.o clip_default.o mtmd.o mtmd-helper.o mtmd-helper-gen.o mtmd-image.o ggml-backend.o ggml-backend-meta.o ggml-backend-reg_default.o ggml-repack.o $(OBJS_FULL) $(OBJS)
+whispermain: otherarch/whispercpp/main.cpp otherarch/whispercpp/whisper.cpp kcpp_backend.h kcpp_backend_default.o build-info.h ggml.o ggml-cpu.o ggml-ops.o ggml-vec.o ggml-binops.o ggml-unops.o llama.o chat.o llama-model.o console.o clip_default.o mtmd.o mtmd-helper.o mtmd-helper-gen.o mtmd-image.o ggml-backend.o ggml-backend-meta.o ggml-backend-reg_default.o ggml-repack.o $(OBJS_FULL) $(OBJS)
 	$(CXX) $(CXXFLAGS) $(filter-out %.h,$^) -o $@ $(LDFLAGS)
 ttsmain: tools/tts/tts.cpp common/arg.cpp common/preset.cpp $(COMMON_DOWNLOAD_SRCS) build-info.h ggml.o ggml-cpu.o ggml-ops.o ggml-vec.o ggml-binops.o ggml-unops.o llama.o chat.o llama-model.o console.o clip_default.o mtmd.o mtmd-helper.o mtmd-helper-gen.o mtmd-image.o ggml-backend.o ggml-backend-meta.o ggml-backend-reg_default.o ggml-repack.o $(OBJS_FULL) $(OBJS)
 	$(CXX) $(CXXFLAGS) $(filter-out %.h,$^) -o $@ $(LDFLAGS)
diff --git a/gpttype_adapter.cpp b/gpttype_adapter.cpp
index 56bd03ef7..fdd85b42b 100644
--- a/gpttype_adapter.cpp
+++ b/gpttype_adapter.cpp
@@ -525,11 +525,10 @@ std::string get_fitted_params_str(const llama_model_params & mparams, const llam
 
 static bool has_tensor_split(const float* ratios, int num_ratios, ggml_backend_t backend = nullptr)
 {
-    if(kcpp_backend_check(KCPP_BACKENDS_TENSOR_SPLIT, backend)) {
-        for (int i = 0; i < tensor_split_max; ++i) {
-            if (ratios[i] != 0.0f) {
-                return true;
-            }
+    const int ratios_count = std::min(num_ratios, tensor_split_max);
+    for (int i = 0; i < ratios_count; ++i) {
+        if (ratios[i] != 0.0f) {
+            return true;
         }
     }
     return false;
@@ -2979,7 +2978,7 @@ static void connect_rpc_servers(const std::string & servers) {
 
 mtmd_context_params init_mtmd_ctx_params(bool mmproj_cpu, bool dryrun)
 {
-    if(kcpp_backend_check("mtl")) {
+    if(kcpp_backend_check(KCPP_BACKENDS_METAL)) {
         if(file_format_meta.model_architecture == llm_arch::LLM_ARCH_QWEN2VL || file_format_meta.model_architecture == llm_arch::LLM_ARCH_GEMMA3)
         {
             mmproj_cpu = true;
@@ -2990,7 +2989,7 @@ mtmd_context_params init_mtmd_ctx_params(bool mmproj_cpu, bool dryrun)
         }
     }
     llama_flash_attn_type mtmd_fa = (kcpp_data->flash_attn?LLAMA_FLASH_ATTN_TYPE_ENABLED:LLAMA_FLASH_ATTN_TYPE_DISABLED);
-    if(kcpp_backend_check("cuda")) {
+    if(kcpp_backend_check(KCPP_BACKENDS_USE_CUDA)) {
         mtmd_fa = LLAMA_FLASH_ATTN_TYPE_DISABLED; //kcpp: disabled in 1.102.2 as some headsizes break on turing
     }
     if(mmproj_cpu)
diff --git a/kcpp_backend.cpp b/kcpp_backend.cpp
index 58a737f40..30564cfab 100644
--- a/kcpp_backend.cpp
+++ b/kcpp_backend.cpp
@@ -33,7 +33,7 @@ static bool has_any_prefix(const std::string& str, const std::string& prefixes,
     size_t end = prefixes.find(delimiter);
     while (start != std::string::npos) {
         std::string prefix = prefixes.substr(start, end - start);
-        if (str.rfind(prefix, 0) == 0) {
+        if (!prefix.empty() && str.rfind(prefix, 0) == 0) {
             return true;
         }
         if (end == std::string::npos) {
@@ -63,13 +63,16 @@ ggml_backend_dev_t kcpp_backend_get_device(int index)
            return ggml_backend_dev_by_type(GGML_BACKEND_DEVICE_TYPE_CPU);
         }
     } else {
+        if ((size_t) index >= ggml_backend_dev_count()) {
+            return nullptr;
+        }
         return ggml_backend_dev_get((size_t)index);
     }
 }
 
 // this is similar to sd_backend_is, except:
 // - if no backend is provided, checks the first ggml device (should be equivalent to a compile-time check)
-// - tests a |-separated list of device names
+// - tests a |-separated list of backend/device name prefixes
 int kcpp_backend_check(const char* name, ggml_backend_t backend)
 {
     std::string loname = to_lowercase(name);
@@ -88,7 +91,7 @@ int kcpp_backend_check(const char* name, ggml_backend_t backend)
             const char * devname = "vulkan";
 
             #elif defined(GGML_USE_METAL)
-            const char * devname = "mtl";
+            const char * devname = "metal";
 
             #elif defined(GGML_USE_HIP)
             const char * devname = "rocm";
@@ -107,19 +110,23 @@ int kcpp_backend_check(const char* name, ggml_backend_t backend)
             #endif
 
             if (devname != nullptr) {
-                return has_any_prefix(devname, name, '|');
+                return has_any_prefix(devname, loname, '|');
             }
         }
 
         dev = get_ggml_main_device();
     } else {
+        std::string lo_backend_name = to_lowercase(ggml_backend_name(backend));
+        if (has_any_prefix(lo_backend_name, loname, '|')) {
+            return true;
+        }
         dev = ggml_backend_get_device(backend);
     }
     if (!dev) {
         return false;
     }
     std::string lo_dev_name = to_lowercase(ggml_backend_dev_name(dev));
-    return has_any_prefix(lo_dev_name, name, '|');
+    return has_any_prefix(lo_dev_name, loname, '|');
 }
 
 bool kcpp_backend_metal_supports_family(ggml_backend_t backend, int family)
@@ -155,7 +162,7 @@ void kcpp_backend_cuda_ggmlv3_set_tensor_split(const float * tensor_split)
 void kcpp_backend_cuda_ggmlv3_transform_tensor(void * data, struct ggml_v3_tensor * tensor)
 {
     #if defined(GGML_USE_CUDA)
-    ggml_v3_cuda_transform_tensor(tensor->data, tensor);
+    ggml_v3_cuda_transform_tensor(data, tensor);
     #endif
 }
 
diff --git a/kcpp_backend.h b/kcpp_backend.h
index 2db63e0ca..ee9932033 100644
--- a/kcpp_backend.h
+++ b/kcpp_backend.h
@@ -7,6 +7,9 @@
 // backends with GGML_USE_CUDA
 #define KCPP_BACKENDS_USE_CUDA "cuda|rocm"
 
+// Metal backend aliases
+#define KCPP_BACKENDS_METAL "metal|mtl"
+
 // backends that support tensor split
 #define KCPP_BACKENDS_TENSOR_SPLIT "cuda|rocm|vulkan"
 
diff --git a/otherarch/llama_v3.cpp b/otherarch/llama_v3.cpp
index 7e5403215..cd4625b88 100644
--- a/otherarch/llama_v3.cpp
+++ b/otherarch/llama_v3.cpp
@@ -1255,7 +1255,7 @@ static void llama_v3_model_load_internal(
             ctx_size +
             mmapped_size - vram_weights; // weights in VRAM not in memory
 
-        if (llama_v3_use_allocator()){
+        if (llama_v3_use_scratch()){
         mem_required +=
             blasbatchmul*MEM_REQ_SCRATCH0_3(hparams.n_ctx).at(model.type) +
             blasbatchmul*MEM_REQ_SCRATCH1_3().at(model.type) +
@@ -1815,15 +1815,15 @@ static bool llama_v3_eval_internal(
     const int64_t n_embd      = hparams.n_embd;
     const int64_t n_vocab     = hparams.n_vocab;
 
-#ifdef LLAMA_V3_USE_ALLOCATOR
-    ggml_v3_allocr_reset(lctx.alloc);
-#endif
+    if (llama_v3_use_allocator()) {
+        ggml_v3_allocr_reset(lctx.alloc);
+    }
 
     ggml_v3_cgraph * gf = llama_v3_build_graph(lctx, tokens, embd, n_tokens, n_past);
 
-#ifdef LLAMA_V3_USE_ALLOCATOR
-    ggml_v3_allocr_alloc_graph(lctx.alloc, gf);
-#endif
+    if (llama_v3_use_allocator()) {
+        ggml_v3_allocr_alloc_graph(lctx.alloc, gf);
+    }
 
     // LLAMA_V3_LOG_INFO("graph build time: %.3f ms (%d nodes, %d leafs)\n", (ggml_v3_time_us() - t_start_us)/1000.0, gf->n_nodes, gf->n_leafs);
 
@@ -3377,8 +3377,7 @@ struct llama_v3_context * llama_v3_new_context_with_model(
             ctx->embedding.resize(hparams.n_embd);
         }
 
-#ifdef LLAMA_V3_USE_ALLOCATOR
-        {
+        if (llama_v3_use_allocator()) {
             static const size_t tensor_alignment = 32;
             // the compute buffer is used to store the tensor and graph structs, while the allocator buffer is used for the tensor data
             ctx->buf_compute.resize(ggml_v3_tensor_overhead()*GGML_V3_MAX_NODES + ggml_v3_graph_overhead());
@@ -3410,10 +3409,9 @@ struct llama_v3_context * llama_v3_new_context_with_model(
             ctx->buf_alloc.resize(alloc_size);
             ctx->alloc = ggml_v3_allocr_new(ctx->buf_alloc.addr, ctx->buf_alloc.size, tensor_alignment);
 
+        } else {
+            ctx->buf_compute.resize(blasbatchmul*MEM_REQ_EVAL_3().at(ctx->model.type) + ggml_v3_graph_overhead());
         }
-#else
-        ctx->buf_compute.resize(blasbatchmul*MEM_REQ_EVAL_3().at(ctx->model.type) + ggml_v3_graph_overhead());
-#endif
 
         if (llama_v3_use_scratch()) {
         ctx->buf_scratch[0].resize(blasbatchmul*MEM_REQ_SCRATCH0_3(hparams.n_ctx).at(ctx->model.type));
diff --git a/otherarch/whispercpp/whisper.cpp b/otherarch/whispercpp/whisper.cpp
index 30e58e3f3..fb335542d 100644
--- a/otherarch/whispercpp/whisper.cpp
+++ b/otherarch/whispercpp/whisper.cpp
@@ -1070,7 +1070,7 @@ static uint32_t whisper_kv_cache_get_padding(const struct whisper_context & wctx
         return 1u;
     }
 
-    if (kcpp_backend_check("mtl", wctx.backend)) {
+    if (kcpp_backend_check(KCPP_BACKENDS_METAL, wctx.backend)) {
         return 32u;
     }
 
@@ -1225,7 +1225,7 @@ static ggml_backend_t whisper_backend_init(const whisper_context_params & params
             if (!backend_gpu) {
                 WHISPER_LOG_ERROR("%s: ggml_backend_dev_init() failed\n", __func__);
             } else {
-                if (kcpp_backend_check("mtl", backend_gpu) && !kcpp_backend_metal_supports_family(backend_gpu, 7)) {
+                if (kcpp_backend_check(KCPP_BACKENDS_METAL, backend_gpu) && !kcpp_backend_metal_supports_family(backend_gpu, 7)) {
                     WHISPER_LOG_ERROR("%s: Metal GPU does not support family 7 - falling back to CPU\n", __func__);
                     ggml_backend_free(backend_gpu);
                     backend_gpu = NULL;
@@ -1861,7 +1861,7 @@ static struct ggml_cgraph * whisper_build_graph_encoder(
         whisper_context & wctx,
           whisper_state & wstate) {
 
-    auto ggml_mul_mat = kcpp_backend_check("mtl", wctx.backend)
+    auto ggml_mul_mat = kcpp_backend_check(KCPP_BACKENDS_METAL, wctx.backend)
                         ? ggml_mul_mat_pad
                         : ggml_mul_mat_original;
 
@@ -2111,7 +2111,7 @@ static struct ggml_cgraph * whisper_build_graph_cross(
         whisper_context & wctx,
           whisper_state & wstate) {
 
-    auto ggml_mul_mat = kcpp_backend_check("mtl", wctx.backend)
+    auto ggml_mul_mat = kcpp_backend_check(KCPP_BACKENDS_METAL, wctx.backend)
                         ? ggml_mul_mat_pad
                         : ggml_mul_mat_original;
 
@@ -2303,7 +2303,7 @@ static struct ggml_cgraph * whisper_build_graph_decoder(
                     bool   save_alignment_heads_QKs,
                     bool   worst_case) {
 
-    auto ggml_mul_mat = kcpp_backend_check("mtl", wctx.backend)
+    auto ggml_mul_mat = kcpp_backend_check(KCPP_BACKENDS_METAL, wctx.backend)
                         ? ggml_mul_mat_pad
                         : ggml_mul_mat_original;
 
@@ -6565,7 +6565,7 @@ WHISPER_API int whisper_bench_ggml_mul_mat(int n_threads) {
 
 WHISPER_API const char * whisper_bench_ggml_mul_mat_str(int n_threads) {
 
-    auto ggml_mul_mat = kcpp_backend_check("mtl")
+    auto ggml_mul_mat = kcpp_backend_check(KCPP_BACKENDS_METAL)
                         ? ggml_mul_mat_pad
                         : ggml_mul_mat_original;