diff --git a/.github/workflows/create-release.yml b/.github/workflows/create-release.yml
index 44e211ec66..25bbce6962 100644
--- a/.github/workflows/create-release.yml
+++ b/.github/workflows/create-release.yml
@@ -813,7 +813,9 @@ jobs:
       # itself" (#1633, measured with conda 26.7.2). So 3.15 leaves base on its
       # own Python: `conda build --python` below builds against 3.15 regardless,
       # measured to build and import pypcapkit-*-py315_0. Drop the exception
-      # once conda publishes a py315 build.
+      # once conda publishes a py315 build. #2123: nor on macos-26-intel, where
+      # changing base's Python rebuilds conda-forge's libmambapy at a version
+      # conda-libmamba-solver cannot drive, failing "Install conda build tools".
       - name: Conda environment creation and activation
         uses: conda-incubator/setup-miniconda@be893c923ea9cf1cf7cd510fbdde27c7e18cbdcb # v4.1.0
         env:
@@ -826,7 +828,7 @@ jobs:
           # that leg installs Miniforge. An empty string names no installer, so
           # the other legs keep the bundled or downloaded Miniconda.
           miniforge-version: ${{ matrix.os == 'macos-26-intel' && 'latest' || '' }}
-          python-version: ${{ matrix.python-version != '3.15' && matrix.python-version || '' }}
+          python-version: ${{ matrix.os != 'macos-26-intel' && matrix.python-version != '3.15' && matrix.python-version || '' }}
           activate-environment: base
           auto-update-conda: false
           auto-activate: true
diff --git a/.github/workflows/cron-conda.yml b/.github/workflows/cron-conda.yml
index ff03ec9f28..b872d476bf 100644
--- a/.github/workflows/cron-conda.yml
+++ b/.github/workflows/cron-conda.yml
@@ -542,7 +542,8 @@ jobs:
           mkdir -p conda/wheels
           python -m pip download -r conda/requirements.txt -d conda/wheels
 
-      # See create-release.yml's step of the same name for the 3.15 exception.
+      # See create-release.yml's step of the same name for the 3.15 and Intel
+      # exceptions (#2123).
       - name: Conda environment creation and activation
         id: miniconda
         continue-on-error: ${{ matrix.os == 'windows-latest' }}
@@ -554,7 +555,7 @@ jobs:
           # #2044: Miniforge on the Intel leg; see create-release.yml's step of
           # the same name.
           miniforge-version: ${{ matrix.os == 'macos-26-intel' && 'latest' || '' }}
-          python-version: ${{ matrix.python-version != '3.15' && matrix.python-version || '' }}
+          python-version: ${{ matrix.os != 'macos-26-intel' && matrix.python-version != '3.15' && matrix.python-version || '' }}
           activate-environment: base
           auto-update-conda: false
           auto-activate: true
diff --git a/conda/pypcapkit/meta.yaml b/conda/pypcapkit/meta.yaml
index 85e8ce7e33..989f56c6cb 100644
--- a/conda/pypcapkit/meta.yaml
+++ b/conda/pypcapkit/meta.yaml
@@ -17,6 +17,10 @@ build:
   entry_points:
     - pcapkit-cli = pcapkit.__main__:main
     - pcapkit-vendor = pcapkit.vendor.__main__:main
+  # #2123: every binary comes from a wheel and links only system libraries, so
+  # none needs an rpath into the prefix. On osx-64, adding one fails on the
+  # vendored chardet extensions, which have no header room for it.
+  binary_relocation: false  # [osx and x86_64]
   #script: "{{ PYTHON }} -m pip install . -vv"
 
 requirements:
diff --git a/tests/project/test_conda_intel_miniforge_2044.py b/tests/project/test_conda_intel_miniforge_2044.py
index a2ceeca51c..4b1780663f 100644
--- a/tests/project/test_conda_intel_miniforge_2044.py
+++ b/tests/project/test_conda_intel_miniforge_2044.py
@@ -17,15 +17,29 @@
 ``installer-url`` first, then Miniforge when ``miniforge-version`` or
 ``miniforge-variant`` is non-empty, else Miniconda.
 
+#2123: with Miniforge, the Intel legs broke twice more. Installing the matrix
+Python into base rebuilt conda-forge's libmambapy at 2.10.0, which
+conda-libmamba-solver 26.10.0 cannot drive, so the Intel legs now leave base's
+Python alone, as 3.15 does everywhere; :class:`TestTheIntelLegsKeepBasesPython`
+pins that. And conda-build 26.9's rpath relocation failed on the vendored chardet
+extensions, so :file:`conda/pypcapkit/meta.yaml` turns it off on osx-64 alone;
+:class:`TestOsx64SkipsBinaryRelocation` evaluates that line's selector as
+conda-build does, for each leg's platform.
+
 """
 
 from __future__ import annotations
 
+import ast
+import pathlib
+import re
 import unittest
 from typing import TYPE_CHECKING
 
 from tests import _workflows
+from tests.project.test_python_versions_1660 import script as versions_script
 from tests.project.test_release_gates import _as_string, evaluate_expression
+from util import release_conda
 
 if TYPE_CHECKING:
     from typing import Any
@@ -110,5 +124,91 @@ def test_no_leg_names_two_installers(self) -> None:
                         self.assertEqual(received['installer-url'], '')
 
 
+def python_input(entry: 'dict[str, Any]', os: 'str', python: 'str') -> 'str':
+    """The ``python-version`` setup-miniconda receives on leg ``os`` with ``python``."""
+    context = {'matrix': {'os': os, 'python-version': python}}  # type: dict[str, object]
+    return _as_string(evaluate_expression(str(entry['with']['python-version']), context)).strip()
+
+
+class TestTheIntelLegsKeepBasesPython(unittest.TestCase):
+    """#2123: no Python install into base on ``macos-26-intel``; the other legs as before."""
+
+    supported = ()  # type: tuple[str, ...]
+
+    @classmethod
+    def setUpClass(cls) -> None:
+        script = versions_script()
+        cls.supported = tuple(script.tier(script.load(), 'cpython', 'supported'))
+
+    def test_the_intel_leg_installs_no_python(self) -> None:
+        self.assertTrue(self.supported, 'no supported CPython to check')
+        for name, job_id in JOBS:
+            for python in self.supported:
+                with self.subTest(workflow=name, job=job_id, python=python):
+                    self.assertEqual(python_input(step(name, job_id), INTEL, python), '')
+
+    def test_the_other_legs_install_the_matrix_python_but_315(self) -> None:
+        for name, job_id in JOBS:
+            for os in legs(name, job_id):
+                if os == INTEL:
+                    continue
+                for python in self.supported:
+                    with self.subTest(workflow=name, job=job_id, os=os, python=python):
+                        expected = '' if python == '3.15' else python
+                        self.assertEqual(python_input(step(name, job_id), os, python), expected)
+
+
+#: The recipe whose ``build:`` section carries the relocation switch.
+META = pathlib.Path(__file__).resolve().parents[2] / 'conda' / 'pypcapkit' / 'meta.yaml'
+#: A ``key: value  # [selector]`` line, as conda-build reads one.
+SELECTED = re.compile(r'^\s*(?P<key>[\w-]+):\s*(?P<value>\S+)\s*#\s*\[(?P<selector>[^\]]+)\]\s*$')
+#: conda-build's ``ARCH_MAP``: the subdir arch names that are not selector names.
+ARCH_MAP = {'32': 'x86', '64': 'x86_64'}
+
+
+def selectors(subdir: 'str') -> 'dict[str, bool]':
+    """The OS and arch selectors conda-build 26.9's ``get_selectors`` sets for ``subdir``."""
+    subdirs = set(release_conda.PLATFORMS.values()) | {subdir, 'linux-aarch64', 'linux-32'}
+    names = {'unix': subdir.startswith(('linux-', 'osx-', 'emscripten-'))}
+    for os in {entry.split('-')[0] for entry in subdirs}:
+        names[os] = subdir.startswith(f'{os}-')
+    for arch in {entry.split('-')[1] for entry in subdirs}:
+        names[ARCH_MAP.get(arch, arch)] = subdir.endswith(f'-{arch}')
+    return names
+
+
+def holds(selector: 'str', names: 'dict[str, bool]') -> 'bool':
+    """Whether ``selector``, of names, ``and``, ``or`` and ``not``, holds; an unknown name raises."""
+    def walk(node: 'ast.AST') -> 'bool':
+        if isinstance(node, ast.BoolOp):
+            values = [walk(value) for value in node.values]
+            return all(values) if isinstance(node.op, ast.And) else any(values)
+        if isinstance(node, ast.UnaryOp) and isinstance(node.op, ast.Not):
+            return not walk(node.operand)
+        if isinstance(node, ast.Name):
+            return names[node.id]
+        raise AssertionError(f'unsupported selector {selector!r}')
+    return walk(ast.parse(selector, mode='eval').body)
+
+
+class TestOsx64SkipsBinaryRelocation(unittest.TestCase):
+    """#2123: ``binary_relocation: false`` on osx-64 alone, so the other platforms still relocate."""
+
+    def line(self) -> 're.Match[str]':
+        found = [match for match in map(SELECTED.match, META.read_text(encoding='utf-8').splitlines())
+                 if match and match['key'] == 'binary_relocation']
+        self.assertEqual(len(found), 1, f'{META.name} has {len(found)} selected binary_relocation lines')
+        return found[0]
+
+    def test_the_line_turns_relocation_off(self) -> None:
+        self.assertEqual(self.line()['value'], 'false')
+
+    def test_it_applies_to_the_intel_legs_platform_alone(self) -> None:
+        selector = self.line()['selector']
+        for os, subdir in sorted(release_conda.PLATFORMS.items()):
+            with self.subTest(os=os, subdir=subdir):
+                self.assertEqual(holds(selector, selectors(subdir)), os == INTEL)
+
+
 if __name__ == '__main__':
     unittest.main()
diff --git a/tests/project/test_python_matrix_tiers_1633.py b/tests/project/test_python_matrix_tiers_1633.py
index b9e73e149c..f64a3aa297 100644
--- a/tests/project/test_python_matrix_tiers_1633.py
+++ b/tests/project/test_python_matrix_tiers_1633.py
@@ -462,7 +462,8 @@ def test_no_conda_leg_is_ktlo_and_315_leaves_base_python_alone(self) -> None:
                 setup = next(step for step in spec['steps']
                              if str(step.get('uses', '')).startswith('conda-incubator/setup-miniconda@'))
                 self.assertEqual(setup['with']['python-version'],
-                                 "${{ matrix.python-version != '3.15' && matrix.python-version || '' }}")
+                                 "${{ matrix.os != 'macos-26-intel' && matrix.python-version != '3.15' && "
+                                 "matrix.python-version || '' }}")
 
 
 #: ``pip`` for an install step, which runs util/pip_install.py on the real