Windows (MSVC) build docs and JSON inspect fix

README.md

@@ -379,6 +379,25 @@ MIYAGI_TEST_GPU_LAYERS=0 \
 cargo test --no-default-features --test model_backend
 ```
 
+### Building on Windows (MSVC)
+
+Miyagi builds and runs on Windows (validated on Windows 11, Rust
+`x86_64-pc-windows-msvc`, against mainline llama.cpp b10054 with an RTX 4090).
+Notes:
+
+- With Visual Studio 18 installed, the `cmake` crate requests the
+  "Visual Studio 18 2026" generator, which needs CMake ≥ 4.3 on `PATH`
+  (VS's bundled CMake works).
+- For `--features cuda` with a VS version newer than your CUDA toolkit's VS
+  integration, use the Ninja generator inside a `vcvars64` environment of a VS
+  version the toolkit supports, e.g.:
+
+  ```bat
+  call "...\BuildTools\VC\Auxiliary\Build\vcvars64.bat"
+  set CMAKE_GENERATOR=Ninja
+  cargo build --release --features cuda
+  ```
+
 ## Compatibility and Boundaries
 
 - Miyagi supports descriptor-driven Qwen/Bonsai MLP mapping for two-dimensional

src/architecture.rs

@@ -96,11 +96,24 @@ impl TensorInfo {
 
 #[derive(Clone, Debug, Eq, PartialEq, Serialize)]
 pub struct ArchitectureMap {
+    // Tuple keys cannot be JSON map keys ("key must be a string"); emit the
+    // tensor list instead — each TensorInfo already carries layer+projection.
+    #[serde(serialize_with = "serialize_tensor_map")]
     tensors: BTreeMap<(usize, Projection), TensorInfo>,
     layer_count: usize,
     signature: String,
 }
 
+fn serialize_tensor_map<S>(
+    tensors: &BTreeMap<(usize, Projection), TensorInfo>,
+    serializer: S,
+) -> std::result::Result<S::Ok, S::Error>
+where
+    S: serde::Serializer,
+{
+    serializer.collect_seq(tensors.values())
+}
+
 impl ArchitectureMap {
     pub fn discover(descriptors: &[TensorDescriptor]) -> Result<Self> {
         let mut tensors = BTreeMap::new();
@@ -295,4 +308,34 @@ mod tests {
             "\"down_proj\""
         );
     }
+
+    #[test]
+    fn architecture_map_json_serializes_tensors_as_array() {
+        let mut descriptors = Vec::new();
+        for layer in 0..2 {
+            descriptors.push(descriptor(
+                &format!("blk.{layer}.ffn_gate.weight"),
+                4096,
+                12288,
+            ));
+            descriptors.push(descriptor(
+                &format!("blk.{layer}.ffn_up.weight"),
+                4096,
+                12288,
+            ));
+            descriptors.push(descriptor(
+                &format!("blk.{layer}.ffn_down.weight"),
+                12288,
+                4096,
+            ));
+        }
+        let map = ArchitectureMap::discover(&descriptors).unwrap();
+        let value = serde_json::to_value(&map).expect("JSON serialize must not fail on tuple keys");
+        let tensors = value
+            .get("tensors")
+            .and_then(|t| t.as_array())
+            .expect("tensors must serialize as a JSON array");
+        assert_eq!(tensors.len(), 6);
+        assert!(tensors.iter().all(|t| t.get("layer").is_some() && t.get("projection").is_some()));
+    }
 }