Simplify Context to hold only ContextHandle

Remove the _h_green_ctx and _is_green fields from Context. The green
context association is already encoded in the ContextHandle's ContextBox
(which carries a GreenCtxHandle dependency). is_green now queries
get_context_green_ctx() on demand. _from_green_ctx delegates to
_from_handle after creating the context handle. close() only resets
_h_context — the ContextBox destructor handles the green ctx cleanup.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: leofang

cuda_core/cuda/core/_context.pxd

@@ -13,9 +13,7 @@ cdef class Context:
 
     cdef:
         ContextHandle _h_context
-        GreenCtxHandle _h_green_ctx
         int _device_id
-        bint _is_green
         object __weakref__
 
     @staticmethod

cuda_core/cuda/core/_context.pyx

@@ -43,23 +43,17 @@ cdef class Context:
         """Create Context from existing ContextHandle (cdef-only factory)."""
         cdef Context ctx = cls.__new__(cls)
         ctx._h_context = h_context
-        ctx._h_green_ctx = get_context_green_ctx(h_context)
         ctx._device_id = device_id
-        ctx._is_green = ctx._h_green_ctx.get() != NULL
         return ctx
 
     @staticmethod
     cdef Context _from_green_ctx(type cls, GreenCtxHandle h_green_ctx, int device_id):
         """Create Context from an owning green context handle."""
-        cdef Context ctx = cls.__new__(cls)
-        ctx._h_green_ctx = h_green_ctx
-        ctx._h_context = create_context_handle_from_green_ctx(h_green_ctx)
-        if not ctx._h_context:
+        cdef ContextHandle h_context = create_context_handle_from_green_ctx(h_green_ctx)
+        if not h_context:
             HANDLE_RETURN(get_last_error())
             raise RuntimeError("Failed to create CUDA context view from green context")
-        ctx._device_id = device_id
-        ctx._is_green = True
-        return ctx
+        return Context._from_handle(cls, h_context, device_id)
 
     @property
     def handle(self):
@@ -77,7 +71,9 @@ cdef class Context:
     @property
     def is_green(self) -> bool:
         """True if this context was created from device resources."""
-        return bool(self._is_green)
+        if not self._h_context:
+            return False
+        return get_context_green_ctx(self._h_context).get() != NULL
 
     cpdef close(self):
         """Release this context wrapper's underlying CUDA handles."""
@@ -91,7 +87,6 @@ cdef class Context:
                     "Restore a previous context before closing this context."
                 )
         self._h_context.reset()
-        self._h_green_ctx.reset()
 
     def __eq__(self, other):
         if not isinstance(other, Context):