From 3095387fdeb3a3b39fd610778a4c9da63f67d042 Mon Sep 17 00:00:00 2001
From: Miranda Mundt <mmundt@sandia.gov>
Date: Wed, 22 Oct 2025 14:57:29 -0600
Subject: [PATCH 01/20] 301st attempt

---
 .github/workflows/test_pr_and_main.yml | 84 ++------------------------
 1 file changed, 6 insertions(+), 78 deletions(-)

diff --git a/.github/workflows/test_pr_and_main.yml b/.github/workflows/test_pr_and_main.yml
index 906d802ce4b..25fcabb0bac 100644
--- a/.github/workflows/test_pr_and_main.yml
+++ b/.github/workflows/test_pr_and_main.yml
@@ -92,21 +92,12 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest, macos-latest, windows-latest]
+        os: [windows-latest]
         python: [ '3.10', 3.11, 3.12, 3.13, 3.14 ]
         other: [""]
         category: [""]
 
         include:
-        - os: ubuntu-latest
-          test_docs: 1
-          TARGET: linux
-          PYENV: pip
-
-        - os: macos-latest
-          test_docs: 1
-          TARGET: osx
-          PYENV: pip
 
         - os: windows-latest
           test_docs: 1
@@ -114,79 +105,12 @@ jobs:
           PYENV: conda
           PACKAGES: glpk pytest-qt filelock
 
-        # Note: verify that pymumps is available when changing conda python version
-        - os: ubuntu-latest
-          python: 3.12
-          other: /conda
-          TARGET: linux
-          PYENV: conda
-          PACKAGES: pytest-qt
-
-        - os: ubuntu-latest
-          python: 3.11
-          other: /mpi
-          mpi: 3
-          TARGET: linux
-          PYENV: conda
-          PACKAGES: openmpi mpi4py
-
-        - os: ubuntu-latest
-          python: 3.12
-          other: /cython
-          setup_options: --with-cython
-          TARGET: linux
-          PYENV: pip
-          PACKAGES: cython
-
         - os: windows-latest
           python: '3.10'
           other: /pip
           TARGET: win
           PYENV: pip
 
-        - os: ubuntu-latest
-          python: 3.11
-          other: /singletest
-          category: "-m 'neos or importtest'"
-          TARGET: linux
-          PYENV: pip
-
-        - os: ubuntu-latest
-          python: '3.10'
-          other: /slim
-          slim: 1
-          TARGET: linux
-          PYENV: pip
-
-        - os: ubuntu-latest
-          python: 3.12
-          other: /numpy2
-          slim: 1
-          TARGET: linux
-          PYENV: pip
-          PACKAGES: "gurobipy dill numpy>2.0 scipy networkx"
-
-        - os: ubuntu-latest
-          python: '3.10'
-          other: /pyutilib
-          TARGET: linux
-          PYENV: pip
-          PACKAGES: pyutilib
-
-        - os: ubuntu-latest
-          python: 'pypy-3.11'
-          TARGET: linux
-          PYENV: pip
-
-        - os: ubuntu-latest
-          python: 3.11
-          other: /rtd
-          category: notests
-          build_docs: 1
-          TARGET: linux
-          PYENV: pip
-
-
     steps:
     - name: Checkout Pyomo source
       uses: actions/checkout@v4
@@ -432,7 +356,9 @@ jobs:
         fi
         # Note: this will fail the build if any installation fails (or
         # possibly if it outputs messages to stderr)
-        conda install --update-deps -q -y python="${{matrix.python}}" $CONDA_DEPENDENCIES
+        conda install -q -y python="${{matrix.python}}" $CONDA_DEPENDENCIES
+        echo "Current conda environment:"
+        conda list | sed 's/^/    /'
         if test -z "${{matrix.slim}}"; then
             # xpress.init() (xpress 9.5.1 from conda) hangs indefinitely
             # on GHA/Windows under Python 3.10 and 3.11.  Exclude that
@@ -499,6 +425,8 @@ jobs:
                 fi
             done
         fi
+        echo "Current conda environment:"
+        conda list | sed 's/^/    /'
         # Re-try Pyomo (optional) dependencies with pip
         echo ""
         echo "Installing packages only available on PyPI"

From 5b2f0fbf99a57585d83224da8f2d3104c75fba93 Mon Sep 17 00:00:00 2001
From: Miranda Mundt <mmundt@sandia.gov>
Date: Wed, 22 Oct 2025 15:20:02 -0600
Subject: [PATCH 02/20] Just install one random thing

---
 .github/workflows/test_pr_and_main.yml | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/.github/workflows/test_pr_and_main.yml b/.github/workflows/test_pr_and_main.yml
index 25fcabb0bac..4e6407e8a15 100644
--- a/.github/workflows/test_pr_and_main.yml
+++ b/.github/workflows/test_pr_and_main.yml
@@ -354,11 +354,13 @@ jobs:
         if test "${{matrix.TARGET}}" == 'win'; then
             CONDA_DEPENDENCIES="$CONDA_DEPENDENCIES setuptools<74.0.0"
         fi
+        # RUNS
+        pip debug
         # Note: this will fail the build if any installation fails (or
         # possibly if it outputs messages to stderr)
-        conda install -q -y python="${{matrix.python}}" $CONDA_DEPENDENCIES
-        echo "Current conda environment:"
-        conda list | sed 's/^/    /'
+        conda install -q -y pytest
+        # FAILS
+        pip debug
         if test -z "${{matrix.slim}}"; then
             # xpress.init() (xpress 9.5.1 from conda) hangs indefinitely
             # on GHA/Windows under Python 3.10 and 3.11.  Exclude that
@@ -425,8 +427,6 @@ jobs:
                 fi
             done
         fi
-        echo "Current conda environment:"
-        conda list | sed 's/^/    /'
         # Re-try Pyomo (optional) dependencies with pip
         echo ""
         echo "Installing packages only available on PyPI"

From 6e36254efae20c2460f3100022630a12fc01c3d3 Mon Sep 17 00:00:00 2001
From: Miranda Mundt <mmundt@sandia.gov>
Date: Wed, 22 Oct 2025 15:26:53 -0600
Subject: [PATCH 03/20] reset statements

---
 .github/workflows/test_pr_and_main.yml | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/test_pr_and_main.yml b/.github/workflows/test_pr_and_main.yml
index 4e6407e8a15..7e420905c87 100644
--- a/.github/workflows/test_pr_and_main.yml
+++ b/.github/workflows/test_pr_and_main.yml
@@ -354,12 +354,12 @@ jobs:
         if test "${{matrix.TARGET}}" == 'win'; then
             CONDA_DEPENDENCIES="$CONDA_DEPENDENCIES setuptools<74.0.0"
         fi
-        # RUNS
+        # PASSES
         pip debug
         # Note: this will fail the build if any installation fails (or
         # possibly if it outputs messages to stderr)
-        conda install -q -y pytest
-        # FAILS
+        conda install --update-deps -q -y python="${{matrix.python}}" pytest
+        # PANICS
         pip debug
         if test -z "${{matrix.slim}}"; then
             # xpress.init() (xpress 9.5.1 from conda) hangs indefinitely

From aea69e8df296084de1027f99a0009eaf312920c4 Mon Sep 17 00:00:00 2001
From: Miranda Mundt <mmundt@sandia.gov>
Date: Wed, 22 Oct 2025 15:34:15 -0600
Subject: [PATCH 04/20] Remove setuptools

---
 .github/workflows/test_pr_and_main.yml | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/.github/workflows/test_pr_and_main.yml b/.github/workflows/test_pr_and_main.yml
index 7e420905c87..c0a185b162a 100644
--- a/.github/workflows/test_pr_and_main.yml
+++ b/.github/workflows/test_pr_and_main.yml
@@ -322,8 +322,6 @@ jobs:
         conda list --show-channel-urls
         which python
         python --version
-        # We need setuptools so we can run Pyomo's setup.py
-        conda install setuptools
         # Note: some pypi packages are not available through conda
         PYOMO_DEPENDENCIES=`python setup.py dependencies \
             --extras "$EXTRAS" | tail -1`
@@ -358,7 +356,7 @@ jobs:
         pip debug
         # Note: this will fail the build if any installation fails (or
         # possibly if it outputs messages to stderr)
-        conda install --update-deps -q -y python="${{matrix.python}}" pytest
+        conda install --update-deps -q -y python="${{matrix.python}}" $CONDA_DEPENDENCIES
         # PANICS
         pip debug
         if test -z "${{matrix.slim}}"; then

From f06fd4d202d25ac3610ba9f5903c5b54d86f6d80 Mon Sep 17 00:00:00 2001
From: Miranda Mundt <mmundt@sandia.gov>
Date: Wed, 22 Oct 2025 15:45:38 -0600
Subject: [PATCH 05/20] Remove some more things

---
 .github/workflows/test_pr_and_main.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/test_pr_and_main.yml b/.github/workflows/test_pr_and_main.yml
index c0a185b162a..0a90e026cb2 100644
--- a/.github/workflows/test_pr_and_main.yml
+++ b/.github/workflows/test_pr_and_main.yml
@@ -356,7 +356,7 @@ jobs:
         pip debug
         # Note: this will fail the build if any installation fails (or
         # possibly if it outputs messages to stderr)
-        conda install --update-deps -q -y python="${{matrix.python}}" $CONDA_DEPENDENCIES
+        conda install -q -y $CONDA_DEPENDENCIES
         # PANICS
         pip debug
         if test -z "${{matrix.slim}}"; then

From e8be275ee94574fcaa09da6b0d57f40685df62a3 Mon Sep 17 00:00:00 2001
From: Miranda Mundt <mmundt@sandia.gov>
Date: Wed, 22 Oct 2025 16:11:53 -0600
Subject: [PATCH 06/20] Okay after which one does it wig

---
 .github/workflows/test_pr_and_main.yml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/test_pr_and_main.yml b/.github/workflows/test_pr_and_main.yml
index 0a90e026cb2..b9427170604 100644
--- a/.github/workflows/test_pr_and_main.yml
+++ b/.github/workflows/test_pr_and_main.yml
@@ -357,8 +357,6 @@ jobs:
         # Note: this will fail the build if any installation fails (or
         # possibly if it outputs messages to stderr)
         conda install -q -y $CONDA_DEPENDENCIES
-        # PANICS
-        pip debug
         if test -z "${{matrix.slim}}"; then
             # xpress.init() (xpress 9.5.1 from conda) hangs indefinitely
             # on GHA/Windows under Python 3.10 and 3.11.  Exclude that
@@ -423,6 +421,8 @@ jobs:
                 if test -z "$_BUILDS"; then
                     echo "WARNING: $PKG is not available"
                 fi
+                # PANICS
+                pip debug
             done
         fi
         # Re-try Pyomo (optional) dependencies with pip

From 60acbcb8e745f212eec5d70b3d1969a998ab2ead Mon Sep 17 00:00:00 2001
From: Miranda Mundt <mmundt@sandia.gov>
Date: Wed, 22 Oct 2025 16:39:14 -0600
Subject: [PATCH 07/20] What happens if we don't install scip

---
 .github/workflows/test_pr_and_main.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/test_pr_and_main.yml b/.github/workflows/test_pr_and_main.yml
index b9427170604..cf689242239 100644
--- a/.github/workflows/test_pr_and_main.yml
+++ b/.github/workflows/test_pr_and_main.yml
@@ -373,7 +373,7 @@ jobs:
             TIMEOUT_MSG="TIMEOUT: killing conda install process"
             PYVER=$(echo "py${{matrix.python}}" | sed 's/\.//g')
             echo "Installing for $PYVER"
-            for PKG in 'cplex>=12.10' docplex gurobi "$XPRESS" cyipopt pymumps scip; do
+            for PKG in 'cplex>=12.10' docplex gurobi "$XPRESS" cyipopt pymumps; do
                 echo ""
                 echo "*** Install $PKG ***"
                 echo ""

From 9e61d68242f326cbfe71c17c5d6ff75b771b45c3 Mon Sep 17 00:00:00 2001
From: Miranda Mundt <mmundt@sandia.gov>
Date: Wed, 22 Oct 2025 17:02:15 -0600
Subject: [PATCH 08/20] Try scip for everyything but win, add back in
 setuptools

---
 .github/workflows/test_pr_and_main.yml | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/test_pr_and_main.yml b/.github/workflows/test_pr_and_main.yml
index cf689242239..c36ade306ea 100644
--- a/.github/workflows/test_pr_and_main.yml
+++ b/.github/workflows/test_pr_and_main.yml
@@ -322,6 +322,8 @@ jobs:
         conda list --show-channel-urls
         which python
         python --version
+        # On 3.14, we need setuptools so we can run Pyomo's setup.py
+        conda install setuptools
         # Note: some pypi packages are not available through conda
         PYOMO_DEPENDENCIES=`python setup.py dependencies \
             --extras "$EXTRAS" | tail -1`
@@ -373,7 +375,11 @@ jobs:
             TIMEOUT_MSG="TIMEOUT: killing conda install process"
             PYVER=$(echo "py${{matrix.python}}" | sed 's/\.//g')
             echo "Installing for $PYVER"
-            for PKG in 'cplex>=12.10' docplex gurobi "$XPRESS" cyipopt pymumps; do
+            SOLVER_LIST="'cplex>=12.10' docplex gurobi $XPRESS cyipopt pymumps"
+            if [[ ${{matrix.TARGET}} != win ]]; then
+                SOLVER_LIST="$SOLVER_LIST scip"
+            fi
+            for PKG in $SOLVER_LIST; do
                 echo ""
                 echo "*** Install $PKG ***"
                 echo ""

From 9c48d33e74268531419cc84cc4186b6961da55ab Mon Sep 17 00:00:00 2001
From: Miranda Mundt <mmundt@sandia.gov>
Date: Thu, 23 Oct 2025 11:40:26 -0600
Subject: [PATCH 09/20] Pin to lower setuptools; add back in update-deps;
 simplify later pip call

---
 .github/workflows/test_pr_and_main.yml | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/test_pr_and_main.yml b/.github/workflows/test_pr_and_main.yml
index c36ade306ea..2b43bd0d5fd 100644
--- a/.github/workflows/test_pr_and_main.yml
+++ b/.github/workflows/test_pr_and_main.yml
@@ -323,7 +323,7 @@ jobs:
         which python
         python --version
         # On 3.14, we need setuptools so we can run Pyomo's setup.py
-        conda install setuptools
+        conda install setuptools 'pip<24.3'
         # Note: some pypi packages are not available through conda
         PYOMO_DEPENDENCIES=`python setup.py dependencies \
             --extras "$EXTRAS" | tail -1`
@@ -358,7 +358,7 @@ jobs:
         pip debug
         # Note: this will fail the build if any installation fails (or
         # possibly if it outputs messages to stderr)
-        conda install -q -y $CONDA_DEPENDENCIES
+        conda install --update-deps -q -y $CONDA_DEPENDENCIES
         if test -z "${{matrix.slim}}"; then
             # xpress.init() (xpress 9.5.1 from conda) hangs indefinitely
             # on GHA/Windows under Python 3.10 and 3.11.  Exclude that
@@ -435,7 +435,7 @@ jobs:
         echo ""
         echo "Installing packages only available on PyPI"
         if test -n "$PYPI_DEPENDENCIES"; then
-            python -m pip install --cache-dir cache/pip $PYPI_DEPENDENCIES
+            pip install --cache-dir cache/pip $PYPI_DEPENDENCIES
         fi
         # remember this python interpreter
         python -c 'import sys; print("PYTHON_EXE=%s" \

From aaf2f7eba2dcb06b1e2731776d65b76bc4ffdfb5 Mon Sep 17 00:00:00 2001
From: Miranda Mundt <mmundt@sandia.gov>
Date: Thu, 23 Oct 2025 11:51:09 -0600
Subject: [PATCH 10/20] Older pip

---
 .github/workflows/test_pr_and_main.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/test_pr_and_main.yml b/.github/workflows/test_pr_and_main.yml
index 2b43bd0d5fd..7064e5d78a0 100644
--- a/.github/workflows/test_pr_and_main.yml
+++ b/.github/workflows/test_pr_and_main.yml
@@ -323,7 +323,7 @@ jobs:
         which python
         python --version
         # On 3.14, we need setuptools so we can run Pyomo's setup.py
-        conda install setuptools 'pip<24.3'
+        conda install setuptools 'pip<24'
         # Note: some pypi packages are not available through conda
         PYOMO_DEPENDENCIES=`python setup.py dependencies \
             --extras "$EXTRAS" | tail -1`

From fa030016229c2b37a9f0d6010c0c4c6e75810a32 Mon Sep 17 00:00:00 2001
From: Miranda Mundt <mmundt@sandia.gov>
Date: Thu, 23 Oct 2025 12:01:05 -0600
Subject: [PATCH 11/20] It upgrades pip against later because of course it does

---
 .github/workflows/test_pr_and_main.yml | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/test_pr_and_main.yml b/.github/workflows/test_pr_and_main.yml
index 7064e5d78a0..b375ec9f5cd 100644
--- a/.github/workflows/test_pr_and_main.yml
+++ b/.github/workflows/test_pr_and_main.yml
@@ -323,7 +323,7 @@ jobs:
         which python
         python --version
         # On 3.14, we need setuptools so we can run Pyomo's setup.py
-        conda install setuptools 'pip<24'
+        conda install setuptools
         # Note: some pypi packages are not available through conda
         PYOMO_DEPENDENCIES=`python setup.py dependencies \
             --extras "$EXTRAS" | tail -1`
@@ -359,6 +359,7 @@ jobs:
         # Note: this will fail the build if any installation fails (or
         # possibly if it outputs messages to stderr)
         conda install --update-deps -q -y $CONDA_DEPENDENCIES
+        conda install -q -y 'pip<24.3'
         if test -z "${{matrix.slim}}"; then
             # xpress.init() (xpress 9.5.1 from conda) hangs indefinitely
             # on GHA/Windows under Python 3.10 and 3.11.  Exclude that

From b60673e7a5ed13f985cee9880e5a04df2c828591 Mon Sep 17 00:00:00 2001
From: Miranda Mundt <mmundt@sandia.gov>
Date: Thu, 23 Oct 2025 12:17:08 -0600
Subject: [PATCH 12/20] Set some vars

---
 .github/workflows/test_pr_and_main.yml | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/test_pr_and_main.yml b/.github/workflows/test_pr_and_main.yml
index b375ec9f5cd..a5b49605b04 100644
--- a/.github/workflows/test_pr_and_main.yml
+++ b/.github/workflows/test_pr_and_main.yml
@@ -322,6 +322,12 @@ jobs:
         conda list --show-channel-urls
         which python
         python --version
+        if test "${{matrix.TARGET}}" = 'win'; then
+            export PROGRAMDATA='C:\ProgramData'
+            export ALLUSERSPROFILE='C:\ProgramData'
+            export PIP_CONFIG_FILE="$RUNNER_TEMP/pip-empty.ini"
+            : > "$PIP_CONFIG_FILE"
+        fi
         # On 3.14, we need setuptools so we can run Pyomo's setup.py
         conda install setuptools
         # Note: some pypi packages are not available through conda
@@ -359,7 +365,6 @@ jobs:
         # Note: this will fail the build if any installation fails (or
         # possibly if it outputs messages to stderr)
         conda install --update-deps -q -y $CONDA_DEPENDENCIES
-        conda install -q -y 'pip<24.3'
         if test -z "${{matrix.slim}}"; then
             # xpress.init() (xpress 9.5.1 from conda) hangs indefinitely
             # on GHA/Windows under Python 3.10 and 3.11.  Exclude that

From 45979d281fcd91838f5931611a089450d4260787 Mon Sep 17 00:00:00 2001
From: Miranda Mundt <mmundt@sandia.gov>
Date: Thu, 23 Oct 2025 12:32:33 -0600
Subject: [PATCH 13/20] Try more things

---
 .github/workflows/test_pr_and_main.yml | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/.github/workflows/test_pr_and_main.yml b/.github/workflows/test_pr_and_main.yml
index a5b49605b04..395f932a812 100644
--- a/.github/workflows/test_pr_and_main.yml
+++ b/.github/workflows/test_pr_and_main.yml
@@ -323,10 +323,21 @@ jobs:
         which python
         python --version
         if test "${{matrix.TARGET}}" = 'win'; then
+            echo $USERPROFILE
+            # Make platformdirs use env vars instead of registry
+            export PLATFORMDIRS_PREFER_ENV=1
+            # Provide the dirs platformdirs/pip expect
             export PROGRAMDATA='C:\ProgramData'
             export ALLUSERSPROFILE='C:\ProgramData'
+            export APPDATA="$USERPROFILE\AppData\Roaming"
+            export LOCALAPPDATA="$USERPROFILE\AppData\Local"
+            # Ensure they exist (best effort)
+            mkdir -p "$APPDATA/pip" "$LOCALAPPDATA/pip" || true
+            # Point pip at an empty config so it doesn't enumerate site configs
             export PIP_CONFIG_FILE="$RUNNER_TEMP/pip-empty.ini"
             : > "$PIP_CONFIG_FILE"
+            # Avoid exercises that trigger config discovery
+            export PIP_DISABLE_PIP_VERSION_CHECK=1
         fi
         # On 3.14, we need setuptools so we can run Pyomo's setup.py
         conda install setuptools

From b2f8b90d3d3aa6b22a0145a004d89a4c146353e6 Mon Sep 17 00:00:00 2001
From: Miranda Mundt <mmundt@sandia.gov>
Date: Thu, 23 Oct 2025 12:50:24 -0600
Subject: [PATCH 14/20] Move the stuff to later jus tin case conda messes it up

---
 .github/workflows/test_pr_and_main.yml | 31 +++++++++-----------------
 1 file changed, 11 insertions(+), 20 deletions(-)

diff --git a/.github/workflows/test_pr_and_main.yml b/.github/workflows/test_pr_and_main.yml
index 395f932a812..625ab190c08 100644
--- a/.github/workflows/test_pr_and_main.yml
+++ b/.github/workflows/test_pr_and_main.yml
@@ -322,23 +322,6 @@ jobs:
         conda list --show-channel-urls
         which python
         python --version
-        if test "${{matrix.TARGET}}" = 'win'; then
-            echo $USERPROFILE
-            # Make platformdirs use env vars instead of registry
-            export PLATFORMDIRS_PREFER_ENV=1
-            # Provide the dirs platformdirs/pip expect
-            export PROGRAMDATA='C:\ProgramData'
-            export ALLUSERSPROFILE='C:\ProgramData'
-            export APPDATA="$USERPROFILE\AppData\Roaming"
-            export LOCALAPPDATA="$USERPROFILE\AppData\Local"
-            # Ensure they exist (best effort)
-            mkdir -p "$APPDATA/pip" "$LOCALAPPDATA/pip" || true
-            # Point pip at an empty config so it doesn't enumerate site configs
-            export PIP_CONFIG_FILE="$RUNNER_TEMP/pip-empty.ini"
-            : > "$PIP_CONFIG_FILE"
-            # Avoid exercises that trigger config discovery
-            export PIP_DISABLE_PIP_VERSION_CHECK=1
-        fi
         # On 3.14, we need setuptools so we can run Pyomo's setup.py
         conda install setuptools
         # Note: some pypi packages are not available through conda
@@ -371,11 +354,19 @@ jobs:
         if test "${{matrix.TARGET}}" == 'win'; then
             CONDA_DEPENDENCIES="$CONDA_DEPENDENCIES setuptools<74.0.0"
         fi
-        # PASSES
-        pip debug
         # Note: this will fail the build if any installation fails (or
         # possibly if it outputs messages to stderr)
         conda install --update-deps -q -y $CONDA_DEPENDENCIES
+        if test "${{matrix.TARGET}}" = 'win'; then
+            echo "" > "$RUNNER_TEMP/pip-empty.ini"
+            export PIP_CONFIG_FILE="$RUNNER_TEMP/pip-empty.ini"
+            # persist for any subshells / subsequent steps that might run a replaced pip
+            echo "PIP_CONFIG_FILE=$RUNNER_TEMP/pip-empty.ini" >> "$GITHUB_ENV"
+            # belt & suspenders: set typical Windows dirs so platformdirs won't wander
+            export PROGRAMDATA="${PROGRAMDATA:-C:\\ProgramData}"
+            export APPDATA="${APPDATA:-$USERPROFILE\\AppData\\Roaming}"
+            export LOCALAPPDATA="${LOCALAPPDATA:-$USERPROFILE\\AppData\\Local}"
+        fi
         if test -z "${{matrix.slim}}"; then
             # xpress.init() (xpress 9.5.1 from conda) hangs indefinitely
             # on GHA/Windows under Python 3.10 and 3.11.  Exclude that
@@ -445,7 +436,7 @@ jobs:
                     echo "WARNING: $PKG is not available"
                 fi
                 # PANICS
-                pip debug
+                pip list
             done
         fi
         # Re-try Pyomo (optional) dependencies with pip

From 0ad7da0fa1012ee89a7451172bacbd88282b8a11 Mon Sep 17 00:00:00 2001
From: Miranda Mundt <mmundt@sandia.gov>
Date: Thu, 23 Oct 2025 13:01:06 -0600
Subject: [PATCH 15/20] Specifically make registry keys

---
 .github/workflows/test_pr_and_main.yml | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/.github/workflows/test_pr_and_main.yml b/.github/workflows/test_pr_and_main.yml
index 625ab190c08..1cb3e0d22a8 100644
--- a/.github/workflows/test_pr_and_main.yml
+++ b/.github/workflows/test_pr_and_main.yml
@@ -358,14 +358,17 @@ jobs:
         # possibly if it outputs messages to stderr)
         conda install --update-deps -q -y $CONDA_DEPENDENCIES
         if test "${{matrix.TARGET}}" = 'win'; then
-            echo "" > "$RUNNER_TEMP/pip-empty.ini"
-            export PIP_CONFIG_FILE="$RUNNER_TEMP/pip-empty.ini"
-            # persist for any subshells / subsequent steps that might run a replaced pip
-            echo "PIP_CONFIG_FILE=$RUNNER_TEMP/pip-empty.ini" >> "$GITHUB_ENV"
-            # belt & suspenders: set typical Windows dirs so platformdirs won't wander
-            export PROGRAMDATA="${PROGRAMDATA:-C:\\ProgramData}"
-            export APPDATA="${APPDATA:-$USERPROFILE\\AppData\\Roaming}"
-            export LOCALAPPDATA="${LOCALAPPDATA:-$USERPROFILE\\AppData\\Local}"
+          # Ensure the registry keys that platformdirs looks for actually exist
+          reg add "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders" ^
+              /v "Common AppData" /t REG_SZ /d "C:\ProgramData" /f
+          reg add "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders" ^
+              /v "AppData" /t REG_EXPAND_SZ /d "%%USERPROFILE%%\AppData\Roaming" /f
+          reg add "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders" ^
+              /v "Local AppData" /t REG_EXPAND_SZ /d "%%USERPROFILE%%\AppData\Local" /f
+          # Helpful environment fallbacks (not strictly required once registry exists)
+          echo "PROGRAMDATA=C:\ProgramData" >> "$GITHUB_ENV"
+          echo "APPDATA=%USERPROFILE%\AppData\Roaming" >> "$GITHUB_ENV"
+          echo "LOCALAPPDATA=%USERPROFILE%\AppData\Local" >> "$GITHUB_ENV"
         fi
         if test -z "${{matrix.slim}}"; then
             # xpress.init() (xpress 9.5.1 from conda) hangs indefinitely

From 167af94a5b58ec2e92f086dc9d154fb2da341d69 Mon Sep 17 00:00:00 2001
From: Miranda Mundt <mmundt@sandia.gov>
Date: Thu, 23 Oct 2025 13:15:46 -0600
Subject: [PATCH 16/20] Try downgrading setuptools, pip, and platformdirs

---
 .github/workflows/test_pr_and_main.yml | 30 ++++++--------------------
 1 file changed, 6 insertions(+), 24 deletions(-)

diff --git a/.github/workflows/test_pr_and_main.yml b/.github/workflows/test_pr_and_main.yml
index 1cb3e0d22a8..27282c06cf7 100644
--- a/.github/workflows/test_pr_and_main.yml
+++ b/.github/workflows/test_pr_and_main.yml
@@ -322,7 +322,7 @@ jobs:
         conda list --show-channel-urls
         which python
         python --version
-        # On 3.14, we need setuptools so we can run Pyomo's setup.py
+        # We need setuptools so we can run Pyomo's setup.py
         conda install setuptools
         # Note: some pypi packages are not available through conda
         PYOMO_DEPENDENCIES=`python setup.py dependencies \
@@ -352,24 +352,12 @@ jobs:
         echo "*** Install Pyomo dependencies ***"
         # For windows, cannot use newer setuptools because of APPSI compilation issues
         if test "${{matrix.TARGET}}" == 'win'; then
-            CONDA_DEPENDENCIES="$CONDA_DEPENDENCIES setuptools<74.0.0"
+            CONDA_DEPENDENCIES="$CONDA_DEPENDENCIES setuptools<65.0.0 platformdirs<3.0 pip<24.0"
         fi
         # Note: this will fail the build if any installation fails (or
         # possibly if it outputs messages to stderr)
-        conda install --update-deps -q -y $CONDA_DEPENDENCIES
-        if test "${{matrix.TARGET}}" = 'win'; then
-          # Ensure the registry keys that platformdirs looks for actually exist
-          reg add "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders" ^
-              /v "Common AppData" /t REG_SZ /d "C:\ProgramData" /f
-          reg add "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders" ^
-              /v "AppData" /t REG_EXPAND_SZ /d "%%USERPROFILE%%\AppData\Roaming" /f
-          reg add "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders" ^
-              /v "Local AppData" /t REG_EXPAND_SZ /d "%%USERPROFILE%%\AppData\Local" /f
-          # Helpful environment fallbacks (not strictly required once registry exists)
-          echo "PROGRAMDATA=C:\ProgramData" >> "$GITHUB_ENV"
-          echo "APPDATA=%USERPROFILE%\AppData\Roaming" >> "$GITHUB_ENV"
-          echo "LOCALAPPDATA=%USERPROFILE%\AppData\Local" >> "$GITHUB_ENV"
-        fi
+        conda install --update-deps -q -y python="${{matrix.python}}" $CONDA_DEPENDENCIES
+        pip list
         if test -z "${{matrix.slim}}"; then
             # xpress.init() (xpress 9.5.1 from conda) hangs indefinitely
             # on GHA/Windows under Python 3.10 and 3.11.  Exclude that
@@ -386,11 +374,7 @@ jobs:
             TIMEOUT_MSG="TIMEOUT: killing conda install process"
             PYVER=$(echo "py${{matrix.python}}" | sed 's/\.//g')
             echo "Installing for $PYVER"
-            SOLVER_LIST="'cplex>=12.10' docplex gurobi $XPRESS cyipopt pymumps"
-            if [[ ${{matrix.TARGET}} != win ]]; then
-                SOLVER_LIST="$SOLVER_LIST scip"
-            fi
-            for PKG in $SOLVER_LIST; do
+            for PKG in 'cplex>=12.10' docplex gurobi "$XPRESS" cyipopt pymumps scip; do
                 echo ""
                 echo "*** Install $PKG ***"
                 echo ""
@@ -438,15 +422,13 @@ jobs:
                 if test -z "$_BUILDS"; then
                     echo "WARNING: $PKG is not available"
                 fi
-                # PANICS
-                pip list
             done
         fi
         # Re-try Pyomo (optional) dependencies with pip
         echo ""
         echo "Installing packages only available on PyPI"
         if test -n "$PYPI_DEPENDENCIES"; then
-            pip install --cache-dir cache/pip $PYPI_DEPENDENCIES
+            python -m pip install --cache-dir cache/pip $PYPI_DEPENDENCIES
         fi
         # remember this python interpreter
         python -c 'import sys; print("PYTHON_EXE=%s" \

From 7475ee5b5513c7dbcb72c33558715dde8d23c0d5 Mon Sep 17 00:00:00 2001
From: Miranda Mundt <mmundt@sandia.gov>
Date: Thu, 23 Oct 2025 13:22:43 -0600
Subject: [PATCH 17/20] Can't do 65

---
 .github/workflows/test_pr_and_main.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/test_pr_and_main.yml b/.github/workflows/test_pr_and_main.yml
index 27282c06cf7..99e68e0607f 100644
--- a/.github/workflows/test_pr_and_main.yml
+++ b/.github/workflows/test_pr_and_main.yml
@@ -352,7 +352,7 @@ jobs:
         echo "*** Install Pyomo dependencies ***"
         # For windows, cannot use newer setuptools because of APPSI compilation issues
         if test "${{matrix.TARGET}}" == 'win'; then
-            CONDA_DEPENDENCIES="$CONDA_DEPENDENCIES setuptools<65.0.0 platformdirs<3.0 pip<24.0"
+            CONDA_DEPENDENCIES="$CONDA_DEPENDENCIES setuptools<74.0.0 platformdirs<3.0 pip<24.0"
         fi
         # Note: this will fail the build if any installation fails (or
         # possibly if it outputs messages to stderr)

From 982af7a3eba530d5566bad3688669c067bb7c989 Mon Sep 17 00:00:00 2001
From: Miranda Mundt <mmundt@sandia.gov>
Date: Thu, 23 Oct 2025 14:10:25 -0600
Subject: [PATCH 18/20] Revert back to normal file with the lines that fix it
 all

---
 .github/workflows/test_pr_and_main.yml | 81 +++++++++++++++++++++++++-
 1 file changed, 78 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/test_pr_and_main.yml b/.github/workflows/test_pr_and_main.yml
index 99e68e0607f..a4d9c941efd 100644
--- a/.github/workflows/test_pr_and_main.yml
+++ b/.github/workflows/test_pr_and_main.yml
@@ -92,12 +92,21 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [windows-latest]
+        os: [ubuntu-latest, macos-latest, windows-latest]
         python: [ '3.10', 3.11, 3.12, 3.13, 3.14 ]
         other: [""]
         category: [""]
 
         include:
+        - os: ubuntu-latest
+          test_docs: 1
+          TARGET: linux
+          PYENV: pip
+
+        - os: macos-latest
+          test_docs: 1
+          TARGET: osx
+          PYENV: pip
 
         - os: windows-latest
           test_docs: 1
@@ -105,12 +114,79 @@ jobs:
           PYENV: conda
           PACKAGES: glpk pytest-qt filelock
 
+        # Note: verify that pymumps is available when changing conda python version
+        - os: ubuntu-latest
+          python: 3.12
+          other: /conda
+          TARGET: linux
+          PYENV: conda
+          PACKAGES: pytest-qt
+
+        - os: ubuntu-latest
+          python: 3.11
+          other: /mpi
+          mpi: 3
+          TARGET: linux
+          PYENV: conda
+          PACKAGES: openmpi mpi4py
+
+        - os: ubuntu-latest
+          python: 3.12
+          other: /cython
+          setup_options: --with-cython
+          TARGET: linux
+          PYENV: pip
+          PACKAGES: cython
+
         - os: windows-latest
           python: '3.10'
           other: /pip
           TARGET: win
           PYENV: pip
 
+        - os: ubuntu-latest
+          python: 3.11
+          other: /singletest
+          category: "-m 'neos or importtest'"
+          TARGET: linux
+          PYENV: pip
+
+        - os: ubuntu-latest
+          python: '3.10'
+          other: /slim
+          slim: 1
+          TARGET: linux
+          PYENV: pip
+
+        - os: ubuntu-latest
+          python: 3.12
+          other: /numpy2
+          slim: 1
+          TARGET: linux
+          PYENV: pip
+          PACKAGES: "gurobipy dill numpy>2.0 scipy networkx"
+
+        - os: ubuntu-latest
+          python: '3.10'
+          other: /pyutilib
+          TARGET: linux
+          PYENV: pip
+          PACKAGES: pyutilib
+
+        - os: ubuntu-latest
+          python: 'pypy-3.11'
+          TARGET: linux
+          PYENV: pip
+
+        - os: ubuntu-latest
+          python: 3.11
+          other: /rtd
+          category: notests
+          build_docs: 1
+          TARGET: linux
+          PYENV: pip
+
+
     steps:
     - name: Checkout Pyomo source
       uses: actions/checkout@v4
@@ -352,12 +428,11 @@ jobs:
         echo "*** Install Pyomo dependencies ***"
         # For windows, cannot use newer setuptools because of APPSI compilation issues
         if test "${{matrix.TARGET}}" == 'win'; then
-            CONDA_DEPENDENCIES="$CONDA_DEPENDENCIES setuptools<74.0.0 platformdirs<3.0 pip<24.0"
+            CONDA_DEPENDENCIES="$CONDA_DEPENDENCIES setuptools<74.0.0 platformdirs<3.0 pip<25.0"
         fi
         # Note: this will fail the build if any installation fails (or
         # possibly if it outputs messages to stderr)
         conda install --update-deps -q -y python="${{matrix.python}}" $CONDA_DEPENDENCIES
-        pip list
         if test -z "${{matrix.slim}}"; then
             # xpress.init() (xpress 9.5.1 from conda) hangs indefinitely
             # on GHA/Windows under Python 3.10 and 3.11.  Exclude that

From 16baa9a732070bd55e9e684c9f033f92cadfba34 Mon Sep 17 00:00:00 2001
From: Miranda Mundt <mmundt@sandia.gov>
Date: Thu, 23 Oct 2025 14:39:10 -0600
Subject: [PATCH 19/20] Sync two files plus add comments

---
 .github/workflows/test_branches.yml    | 4 +++-
 .github/workflows/test_pr_and_main.yml | 4 +++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/test_branches.yml b/.github/workflows/test_branches.yml
index 109aa2c38d5..b567c3bfbe8 100644
--- a/.github/workflows/test_branches.yml
+++ b/.github/workflows/test_branches.yml
@@ -375,8 +375,10 @@ jobs:
         echo ""
         echo "*** Install Pyomo dependencies ***"
         # For windows, cannot use newer setuptools because of APPSI compilation issues
+        # There are also issues with newer platformdirs on windows for 3.13/3.14,
+        # so pinning that plus a generally considered more "stable" pip version
         if test "${{matrix.TARGET}}" == 'win'; then
-            CONDA_DEPENDENCIES="$CONDA_DEPENDENCIES setuptools<74.0.0"
+            CONDA_DEPENDENCIES="$CONDA_DEPENDENCIES setuptools<74.0.0 platformdirs<3.0 pip<25.0"
         fi
         # Note: this will fail the build if any installation fails (or
         # possibly if it outputs messages to stderr)
diff --git a/.github/workflows/test_pr_and_main.yml b/.github/workflows/test_pr_and_main.yml
index a4d9c941efd..f6a2eb5d1b8 100644
--- a/.github/workflows/test_pr_and_main.yml
+++ b/.github/workflows/test_pr_and_main.yml
@@ -426,7 +426,9 @@ jobs:
         done
         echo ""
         echo "*** Install Pyomo dependencies ***"
-        # For windows, cannot use newer setuptools because of APPSI compilation issues
+        # For windows, cannot use newer setuptools because of APPSI compilation issues.
+        # There are also issues with newer platformdirs on windows for 3.13/3.14,
+        # so pinning that plus a generally considered more "stable" pip version
         if test "${{matrix.TARGET}}" == 'win'; then
             CONDA_DEPENDENCIES="$CONDA_DEPENDENCIES setuptools<74.0.0 platformdirs<3.0 pip<25.0"
         fi

From 56212b083740d324cbd9cb44587ed89a73946ee3 Mon Sep 17 00:00:00 2001
From: Miranda Mundt <mmundt@sandia.gov>
Date: Thu, 23 Oct 2025 17:37:05 -0600
Subject: [PATCH 20/20] Specifically avoid 4.5.0

---
 .github/workflows/test_branches.yml    | 6 +++---
 .github/workflows/test_pr_and_main.yml | 8 ++++----
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/.github/workflows/test_branches.yml b/.github/workflows/test_branches.yml
index b567c3bfbe8..530ab9cc4e1 100644
--- a/.github/workflows/test_branches.yml
+++ b/.github/workflows/test_branches.yml
@@ -375,10 +375,10 @@ jobs:
         echo ""
         echo "*** Install Pyomo dependencies ***"
         # For windows, cannot use newer setuptools because of APPSI compilation issues
-        # There are also issues with newer platformdirs on windows for 3.13/3.14,
-        # so pinning that plus a generally considered more "stable" pip version
+        # There seems to be some specific problem with platformdirs 4.5.0
+        # on win 3.13/3.14 as of 2025-10-23
         if test "${{matrix.TARGET}}" == 'win'; then
-            CONDA_DEPENDENCIES="$CONDA_DEPENDENCIES setuptools<74.0.0 platformdirs<3.0 pip<25.0"
+            CONDA_DEPENDENCIES="$CONDA_DEPENDENCIES setuptools<74.0.0 platformdirs!=4.5.0"
         fi
         # Note: this will fail the build if any installation fails (or
         # possibly if it outputs messages to stderr)
diff --git a/.github/workflows/test_pr_and_main.yml b/.github/workflows/test_pr_and_main.yml
index f6a2eb5d1b8..59924f6d0e1 100644
--- a/.github/workflows/test_pr_and_main.yml
+++ b/.github/workflows/test_pr_and_main.yml
@@ -426,11 +426,11 @@ jobs:
         done
         echo ""
         echo "*** Install Pyomo dependencies ***"
-        # For windows, cannot use newer setuptools because of APPSI compilation issues.
-        # There are also issues with newer platformdirs on windows for 3.13/3.14,
-        # so pinning that plus a generally considered more "stable" pip version
+        # For windows, cannot use newer setuptools because of APPSI compilation issues
+        # There seems to be some specific problem with platformdirs 4.5.0
+        # on win 3.13/3.14 as of 2025-10-23
         if test "${{matrix.TARGET}}" == 'win'; then
-            CONDA_DEPENDENCIES="$CONDA_DEPENDENCIES setuptools<74.0.0 platformdirs<3.0 pip<25.0"
+            CONDA_DEPENDENCIES="$CONDA_DEPENDENCIES setuptools<74.0.0 platformdirs!=4.5.0"
         fi
         # Note: this will fail the build if any installation fails (or
         # possibly if it outputs messages to stderr)