feat(multimodal): route Qwen3.5 family to Qwen3-VL processor (#1563)

Author: chenht2022

crates/multimodal/src/registry/qwen3_vl.rs

@@ -28,10 +28,13 @@ impl ModelProcessorSpec for Qwen3VLVisionSpec {
 
     fn matches(&self, metadata: &ModelMetadata) -> bool {
         let id = metadata.model_id.to_ascii_lowercase();
-        id.contains("qwen3") && id.contains("vl")
-            || metadata
-                .config_model_type()
-                .is_some_and(|mt| mt == "qwen3_vl")
+        let model_type = metadata.config_model_type();
+        let is_qwen3_vl = id.contains("qwen3") && id.contains("vl")
+            || model_type.is_some_and(|mt| mt == "qwen3_vl");
+        let is_qwen3_5 = id.contains("qwen3.5")
+            || id.contains("qwen3.6")
+            || model_type.is_some_and(|mt| mt == "qwen3_5" || mt == "qwen3_5_moe");
+        is_qwen3_vl || is_qwen3_5
     }
 
     fn placeholder_token(&self, metadata: &ModelMetadata) -> RegistryResult<String> {
@@ -178,4 +181,23 @@ mod tests {
             .expect("should match qwen3 alias");
         assert_eq!(spec.name(), "qwen3_vl");
     }
+
+    #[test]
+    fn qwen3_5_matches_alias_via_model_type() {
+        let tokenizer = TestTokenizer::new(&[("<|image_pad|>", 151655)]);
+        let config = json!({
+            "model_type": "qwen3_5_moe",
+            "image_token_id": 151655,
+        });
+        let metadata = ModelMetadata {
+            model_id: "custom-model",
+            tokenizer: &tokenizer,
+            config: &config,
+        };
+        let registry = ModelRegistry::new();
+        let spec = registry
+            .lookup(&metadata)
+            .expect("should match qwen3.5 alias");
+        assert_eq!(spec.name(), "qwen3_vl");
+    }
 }

crates/multimodal/src/vision/image_processor.rs

@@ -376,6 +376,7 @@ impl ImageProcessorRegistry {
     /// - `qwen2-vl` -> Qwen2VLProcessor
     /// - `qwen2.5-vl` -> Qwen2VLProcessor (same preprocessing as Qwen2-VL)
     /// - `qwen3-vl` -> Qwen3VLProcessor (patch_size=16, [0.5,0.5,0.5] normalization)
+    /// - `qwen3.5` / `qwen3_5` -> Qwen3VLProcessor (Qwen3.5 reuses Qwen3-VL preprocessing)
     /// - `phi-3-vision` -> Phi3VisionProcessor (HD transform with 336x336 tiles)
     pub fn with_defaults() -> Self {
         let mut registry = Self::new();
@@ -416,6 +417,24 @@ impl ImageProcessorRegistry {
             Box::new(super::processors::Qwen3VLProcessor::new()),
         );
 
+        // Qwen3.5 family (and Qwen3.6: same arch) reuses Qwen3-VL preprocessing.
+        registry.register(
+            "qwen3.5",
+            Box::new(super::processors::Qwen3VLProcessor::new()),
+        );
+        registry.register(
+            "qwen3_5",
+            Box::new(super::processors::Qwen3VLProcessor::new()),
+        );
+        registry.register(
+            "qwen3.6",
+            Box::new(super::processors::Qwen3VLProcessor::new()),
+        );
+        registry.register(
+            "qwen3_6",
+            Box::new(super::processors::Qwen3VLProcessor::new()),
+        );
+
         // Register Qwen2-VL (matches Qwen/Qwen2-VL-*, etc.)
         registry.register(
             "qwen2-vl",