PY-90203 fix conda_packaging_tool.py compatibility with conda 26

conda 26 changed the SubdirData.query_all signature: channels and subdirs
  are now required keyword arguments. conda 25 inferred them from the current
  context when only a MatchSpec was passed. Calling query_all with just a spec
  on conda 26 raises TypeError, breaking the package index loading entirely.

  Fix: try the explicit form with channels= and subdirs= kwargs first (required
  by conda 26), catch TypeError and fall back to the single-spec form (conda 25
  and earlier). Also add CONDA_26 (py312_26.5.3-1) to PredefinedPyEnvironments
  and CondaPackagingToolHelperTest so future regressions in the version-routing
  logic are caught before release.

(cherry picked from commit 807bc29f329a3ca1c323ccc2fd6f2e7a391be2df)

IJ-MR-212935

GitOrigin-RevId: 8c6b42702a4ed3fd88f00b4e5a6ef9b3ade38853

python/helpers/conda_packaging_tool.py

@@ -44,10 +44,8 @@ def _iter_packages(major_version, minor_version):
     objects (attribute access) instead of the legacy dict-like entries returned by ``get_index``.
     """
     if major_version >= 25:
-        init_context()
-        from conda.core.subdir_data import SubdirData
-        for pkg in SubdirData.query_all('*'):
-            yield Pkg(name=pkg.name, version=pkg.version, depends=pkg.depends)
+        for pkg in _iter_packages_subdir_data():
+            yield pkg
         return
 
     if major_version >= 22 or (major_version >= 4 and minor_version >= 4):
@@ -68,6 +66,39 @@ def _iter_packages(major_version, minor_version):
         yield Pkg(name=pkg["name"], version=pkg["version"], depends=pkg["depends"])
 
 
+def _iter_packages_subdir_data():
+    """Iterate package records via ``SubdirData`` for conda 25+.
+
+    The ``SubdirData.query_all`` signature changed across releases: conda 25 accepts a single
+    positional ``MatchSpec`` and infers ``channels``/``subdirs`` from the current context, while
+    conda 26 made ``channels`` and ``subdirs`` required keyword arguments (passing only the spec
+    raises ``TypeError``). Try the modern explicit form first, then fall back to the older one.
+    """
+    context = init_context()
+    from conda.core.subdir_data import SubdirData
+    try:
+        from conda.models.match_spec import MatchSpec
+        spec = MatchSpec("*")
+    except ImportError:
+        spec = "*"
+
+    channels = getattr(context, "channels", None) if context is not None else None
+    subdirs = getattr(context, "subdirs", None) if context is not None else None
+
+    records = None
+    if channels is not None and subdirs is not None:
+        try:
+            records = SubdirData.query_all(spec, channels=channels, subdirs=subdirs)
+        except TypeError:
+            records = None
+
+    if records is None:
+        records = SubdirData.query_all(spec)
+
+    for pkg in records:
+        yield Pkg(name=pkg.name, version=pkg.version, depends=pkg.depends)
+
+
 def do_list_channels():
     context = init_context()
     if context:

python/python-test-env/common/src/com/intellij/python/test/env/common/PredefinedPyEnvironments.kt

@@ -211,6 +211,15 @@ enum class PredefinedPyEnvironments(val spec: PyEnvironmentSpec<*>) {
    */
   CONDA_25(condaEnvironment("py312_25.11.1-1") {
     pythonVersion = pythonVersion("3.12")
+  }),
+
+  /**
+   * Conda 26.x environment used by helper-script tests to verify that the index-loading
+   * code path continues to work on the latest major conda release.
+   * Tags: conda, conda26
+   */
+  CONDA_26(condaEnvironment("py312_26.5.3-1") {
+    pythonVersion = pythonVersion("3.12")
   });
 
   companion object {
@@ -241,7 +250,8 @@ enum class PredefinedPyEnvironments(val spec: PyEnvironmentSpec<*>) {
       VENV_3_14 to setOf("python3", "python3.14", "ruff"),
       VANILLA_3_14 to setOf("vanilla"),
       CONDA to setOf("conda"),
-      CONDA_25 to setOf("conda", "conda25")
+      CONDA_25 to setOf("conda", "conda25"),
+      CONDA_26 to setOf("conda", "conda26")
     )
   }
 }