feat: Add ColBERT late interaction model support (#33686)

Signed-off-by: Ilya Boytsov <ilyaboytsov1805@gmail.com>
Signed-off-by: Ilya Boytsov <boytsovpanamera@mail.ru>
Co-authored-by: Cyrus Leung <cyrus.tl.leung@gmail.com>
Co-authored-by: wang.yuqi <yuqi.wang@daocloud.io>

vllm/model_executor/models/interfaces.py

@@ -981,6 +981,40 @@ def supports_cross_encoding(
     return is_pooling_model(model) and _supports_cross_encoding(model)
 
 
+@runtime_checkable
+class SupportsLateInteraction(Protocol):
+    """The interface required for all models that support late interaction.
+
+    Late interaction models (like ColBERT) encode queries and documents
+    separately into per-token embeddings, then compute similarity via
+    MaxSim (max over document tokens, sum over query tokens).
+    """
+
+    supports_late_interaction: ClassVar[Literal[True]] = True
+
+
+@overload
+def supports_late_interaction(
+    model: type[object],
+) -> TypeIs[type[SupportsLateInteraction]]: ...
+
+
+@overload
+def supports_late_interaction(model: object) -> TypeIs[SupportsLateInteraction]: ...
+
+
+def _supports_late_interaction(
+    model: type[object] | object,
+) -> TypeIs[type[SupportsLateInteraction]] | TypeIs[SupportsLateInteraction]:
+    return getattr(model, "supports_late_interaction", False)
+
+
+def supports_late_interaction(
+    model: type[object] | object,
+) -> TypeIs[type[SupportsLateInteraction]] | TypeIs[SupportsLateInteraction]:
+    return is_pooling_model(model) and _supports_late_interaction(model)
+
+
 class SupportsQuant:
     """The interface required for all models that support quantization."""