FIX: Add overloads for DataArray.argmin and DataArray.argmax on dim parameter (pydata#11233)

* Fix mypy overload-overlap error for argmin and argmax

- Move `# type: ignore[overload-overlap]` to the @overload decorator
- Add whats-new entry

* Fix placement type: ignore comments for argmin and argmax

* Fix indentation in whats-new.rst

---------

Co-authored-by: Michael Niklas <mick.niklas@gmail.com>

Author: SurfyPenguin

doc/whats-new.rst

@@ -135,6 +135,10 @@ Internal Changes
 - Remove ``setup.py`` file (:pull:`11261`).
   By `Nick Hodgskin <https://github.com/VeckoTheGecko>`_.
 
+- Add :func:`typing.overload` decorators to :py:meth:`DataArray.argmin` and :py:meth:`DataArray.argmax`
+  to narrow return type based on ``dim`` parameter (:issue:`10893` :pull:`11233`).
+  By `Amartya Anand <https://github.com/SurfyPenguin>`_.
+
 .. _whats-new.2026.02.0:
 
 v2026.02.0 (Feb 13, 2026)

xarray/core/dataarray.py

@@ -5,6 +5,7 @@
 import warnings
 from collections.abc import (
     Callable,
+    Collection,
     Hashable,
     Iterable,
     Mapping,
@@ -6187,6 +6188,26 @@ def idxmax(
             keep_attrs=keep_attrs,
         )
 
+    @overload
+    def argmin(  # type: ignore[overload-overlap]
+        self,
+        dim: str,
+        *,
+        axis: int | None = None,
+        keep_attrs: bool | None = None,
+        skipna: bool | None = None,
+    ) -> Self: ...
+
+    @overload
+    def argmin(
+        self,
+        dim: Collection[Hashable] | EllipsisType | None = None,
+        *,
+        axis: int | None = None,
+        keep_attrs: bool | None = None,
+        skipna: bool | None = None,
+    ) -> dict[Hashable, Self]: ...
+
     def argmin(
         self,
         dim: Dims = None,
@@ -6288,6 +6309,26 @@ def argmin(
         else:
             return self._replace_maybe_drop_dims(result)
 
+    @overload
+    def argmax(  # type: ignore[overload-overlap]
+        self,
+        dim: str,
+        *,
+        axis: int | None = None,
+        keep_attrs: bool | None = None,
+        skipna: bool | None = None,
+    ) -> Self: ...
+
+    @overload
+    def argmax(
+        self,
+        dim: Collection[Hashable] | EllipsisType | None = None,
+        *,
+        axis: int | None = None,
+        keep_attrs: bool | None = None,
+        skipna: bool | None = None,
+    ) -> dict[Hashable, Self]: ...
+
     def argmax(
         self,
         dim: Dims = None,