Merge branch 'upstream' into concedo_experimental

# Conflicts:
#	README.md
#	docs/backend/SYCL.md
#	ggml/CMakeLists.txt
#	ggml/src/ggml-cpu/repack.cpp
#	ggml/src/ggml-sycl/backend.hpp
#	ggml/src/ggml-sycl/common.hpp
#	ggml/src/ggml-sycl/convert.cpp
#	ggml/src/ggml-sycl/cpy.cpp
#	ggml/src/ggml-sycl/cpy.hpp
#	ggml/src/ggml-sycl/dequantize.hpp
#	ggml/src/ggml-sycl/fattn.cpp
#	ggml/src/ggml-sycl/fattn.hpp
#	ggml/src/ggml-sycl/ggml-sycl.cpp
#	ggml/src/ggml-sycl/mmvq.cpp
#	ggml/src/ggml-sycl/norm.cpp
#	ggml/src/ggml-sycl/norm.hpp
#	ggml/src/ggml-sycl/vecdotq.hpp
#	ggml/src/ggml-webgpu/ggml-webgpu-shader-lib.hpp
#	ggml/src/ggml-webgpu/ggml-webgpu.cpp
#	ggml/src/ggml-webgpu/wgsl-shaders/common_decls.tmpl
#	ggml/src/ggml-webgpu/wgsl-shaders/flash_attn.wgsl
#	ggml/src/ggml-webgpu/wgsl-shaders/flash_attn_quant_staging.tmpl
#	ggml/src/ggml-webgpu/wgsl-shaders/flash_attn_tile.wgsl
#	ggml/src/ggml-webgpu/wgsl-shaders/flash_attn_vec_split.wgsl
#	ggml/src/ggml-zendnn/CMakeLists.txt
#	ggml/src/ggml-zendnn/ggml-zendnn.cpp
#	scripts/sync-ggml.last
#	tests/CMakeLists.txt
#	tests/snapshots/qwen3.6-27b.schema
#	tests/test-autorelease.cpp
#	tests/test-backend-ops.cpp
#	tests/test-backend-sampler.cpp
#	tests/test-model-load-cancel.cpp
#	tests/test-quant-type-selection.cpp

src/llama-context.cpp

@@ -482,6 +482,9 @@ llama_context::llama_context(
 }
 
 llama_context::~llama_context() {
+    // wait for any pending asynchronous copies into the output buffers before they are freed
+    synchronize();
+
     if (!model.hparams.no_alloc) {
         for (size_t i = 0; i < backend_ptrs.size(); ++i) {
             ggml_backend_t             backend = backend_ptrs[i];
@@ -1427,13 +1430,17 @@ int llama_context::encode(const llama_batch & batch_inp) {
     // micro-batching is not possible for non-causal encoding, so we process the batch in a single shot
     GGML_ASSERT(cparams.n_ubatch >= n_tokens && "encoder requires n_ubatch >= n_tokens");
 
+    // TODO: this clear of the buffer can easily be forgotten - need something better
+    // sync first so any in-flight async copies into embd_seq complete before it is freed
+    if (!embd_seq.empty()) {
+        synchronize();
+    }
+    embd_seq.clear();
+
     if (t_compute_start_us == 0) {
         t_compute_start_us = ggml_time_us();
     }
 
-    // TODO: this clear of the buffer can easily be forgotten - need something better
-    embd_seq.clear();
-
     sched_reserve();
 
     n_queued_tokens += n_tokens;
@@ -1772,13 +1779,18 @@ int llama_context::decode(const llama_batch & batch_inp) {
 
     // GGML_ASSERT((cparams.causal_attn || cparams.n_ubatch >= n_tokens_all) && "non-causal attention requires n_ubatch >= n_tokens");
 
+    // TODO: this clear of the buffer can easily be forgotten - need something better
+    // sync first so any in-flight async copies into embd_seq complete before it is freed
+    if (!embd_seq.empty()) {
+        synchronize();
+    }
+    embd_seq.clear();
+
     if (t_compute_start_us == 0) {
         t_compute_start_us = ggml_time_us();
     }
     n_queued_tokens += n_tokens_all;
 
-    // TODO: this clear of the buffer can easily be forgotten - need something better
-    embd_seq.clear();
     output_swaps.clear();
 
     sched_reserve();
@@ -3551,6 +3563,22 @@ llama_context * llama_init_from_model(
         }
     }
 
+    if ((model->hparams.is_mla() || model->arch == LLM_ARCH_DEEPSEEK4) && params.type_k != params.type_v) {
+        LLAMA_LOG_ERROR("%s: model does not support different K (%s) and V (%s) cache types\n", __func__, ggml_type_name(params.type_k), ggml_type_name(params.type_v));
+        return nullptr;
+    }
+
+    if (ggml_is_quantized(params.type_v) && params.flash_attn_type != LLAMA_FLASH_ATTN_TYPE_ENABLED) {
+        if (params.flash_attn_type == LLAMA_FLASH_ATTN_TYPE_AUTO) {
+            LLAMA_LOG_INFO("%s: enabling flash_attn since it is required for quantized V cache\n", __func__);
+            params.flash_attn_type = LLAMA_FLASH_ATTN_TYPE_ENABLED;
+        }
+        if (params.flash_attn_type == LLAMA_FLASH_ATTN_TYPE_DISABLED) {
+            LLAMA_LOG_ERROR("%s: quantized V cache requires flash_attn to be enabled\n", __func__);
+            return nullptr;
+        }
+    }
+
     if (params.flash_attn_type != LLAMA_FLASH_ATTN_TYPE_DISABLED && ggml_is_quantized(params.type_k)) {
         const uint32_t blck_size = ggml_blck_size(params.type_k);
         for (uint32_t il = 0; il < model->hparams.n_layer(); ++il) {
@@ -3573,11 +3601,6 @@ llama_context * llama_init_from_model(
         }
     }
 
-    if (ggml_is_quantized(params.type_v) && params.flash_attn_type == LLAMA_FLASH_ATTN_TYPE_DISABLED) {
-        LLAMA_LOG_ERROR("%s: V cache quantization requires flash_attn\n", __func__);
-        return nullptr;
-    }
-
     if (params.pooling_type != LLAMA_POOLING_TYPE_UNSPECIFIED &&
         params.pooling_type != model->hparams.pooling_type) {
         //user-specified pooling-type is different from the model default