From 2bdc8c9df214f111ca6628e157dd2061312b41fc Mon Sep 17 00:00:00 2001
From: M Bussonnier <bussonniermatthias@gmail.com>
Date: Sun, 8 Feb 2026 16:50:31 +0100
Subject: [PATCH 1/8] Copy binder config from jupyter_collaboration.

---
 .github/workflows/binder-badge.yml | 14 ++++++++++++++
 binder/environment.yml             | 20 ++++++++++++++++++++
 binder/jupyter_config.py           |  9 +++++++++
 binder/postBuild                   | 26 ++++++++++++++++++++++++++
 4 files changed, 69 insertions(+)
 create mode 100644 .github/workflows/binder-badge.yml
 create mode 100644 binder/environment.yml
 create mode 100644 binder/jupyter_config.py
 create mode 100755 binder/postBuild

diff --git a/.github/workflows/binder-badge.yml b/.github/workflows/binder-badge.yml
new file mode 100644
index 00000000..87e9cd29
--- /dev/null
+++ b/.github/workflows/binder-badge.yml
@@ -0,0 +1,14 @@
+name: Binder Badge
+on:
+  pull_request_target:
+    types: [opened]
+
+jobs:
+  binder:
+    runs-on: ubuntu-latest
+    permissions:
+      pull-requests: write
+    steps:
+      - uses: jupyterlab/maintainer-tools/.github/actions/binder-link@v1
+        with:
+          github_token: ${{ secrets.github_token }}
diff --git a/binder/environment.yml b/binder/environment.yml
new file mode 100644
index 00000000..d5fc8eb1
--- /dev/null
+++ b/binder/environment.yml
@@ -0,0 +1,20 @@
+name: example-environment
+channels:
+  - conda-forge
+  - nodefaults
+dependencies:
+  - jupyterlab >=4.0.0
+  - nodejs >=25,<26
+  - python >=3.11,<3.12
+  - yarn >=3,<4
+  # build
+  - hatchling >=1.5.0
+  - hatch-jupyter-builder >=0.3.2
+  - hatch-nodejs-version
+  # dependencies
+  - jupyter_server >=2.0.0
+  # Use pip to get the the latest version
+  - pip:
+    - jupyter_server_fileid >=0.7.0
+    - jupyter_ydoc >=1.0.0
+    - ypy-websocket >=0.12.0
diff --git a/binder/jupyter_config.py b/binder/jupyter_config.py
new file mode 100644
index 00000000..e5cb76ba
--- /dev/null
+++ b/binder/jupyter_config.py
@@ -0,0 +1,9 @@
+# Copyright (c) Jupyter Development Team.
+# Distributed under the terms of the Modified BSD License.
+import logging
+
+c.ServerApp.log_level = logging.DEBUG
+
+c.ContentsManager.allow_hidden = True
+# Use advance file ID service for out of band rename support
+c.FileIdExtension.file_id_manager_class = "jupyter_server_fileid.manager.LocalFileIdManager"
diff --git a/binder/postBuild b/binder/postBuild
new file mode 100755
index 00000000..aaa4e964
--- /dev/null
+++ b/binder/postBuild
@@ -0,0 +1,26 @@
+#!/usr/bin/env bash
+
+# Copyright (c) Jupyter Development Team.
+# Distributed under the terms of the Modified BSD License.
+
+source activate ${NB_PYTHON_PREFIX}
+
+set -euxo pipefail
+
+yarn || yarn
+
+python -m pip install -vv -e . --no-build-isolation
+jupyter server extension enable nbdime
+
+mkdir -p ~/.jupyter/
+
+cp binder/jupyter_config.py ~/.jupyter/
+
+# FIXME until jupyter-server is the default on binder
+cp ${NB_PYTHON_PREFIX}/bin/jupyter-lab ${NB_PYTHON_PREFIX}/bin/jupyter-notebook
+
+jupyter troubleshoot
+jupyter notebook --show-config
+jupyter lab --show-config
+jupyter labextension list
+jupyter server extension list

From 6034a959519456140c4ff439ee47786d53ce9adc Mon Sep 17 00:00:00 2001
From: M Bussonnier <bussonniermatthias@gmail.com>
Date: Tue, 10 Feb 2026 09:40:34 +0100
Subject: [PATCH 2/8] cleanup

---
 binder/environment.yml   | 7 +------
 binder/jupyter_config.py | 2 --
 binder/postBuild         | 3 ---
 3 files changed, 1 insertion(+), 11 deletions(-)

diff --git a/binder/environment.yml b/binder/environment.yml
index d5fc8eb1..f38e4f92 100644
--- a/binder/environment.yml
+++ b/binder/environment.yml
@@ -5,7 +5,7 @@ channels:
 dependencies:
   - jupyterlab >=4.0.0
   - nodejs >=25,<26
-  - python >=3.11,<3.12
+  - python >=3.14
   - yarn >=3,<4
   # build
   - hatchling >=1.5.0
@@ -13,8 +13,3 @@ dependencies:
   - hatch-nodejs-version
   # dependencies
   - jupyter_server >=2.0.0
-  # Use pip to get the the latest version
-  - pip:
-    - jupyter_server_fileid >=0.7.0
-    - jupyter_ydoc >=1.0.0
-    - ypy-websocket >=0.12.0
diff --git a/binder/jupyter_config.py b/binder/jupyter_config.py
index e5cb76ba..9720647c 100644
--- a/binder/jupyter_config.py
+++ b/binder/jupyter_config.py
@@ -5,5 +5,3 @@
 c.ServerApp.log_level = logging.DEBUG
 
 c.ContentsManager.allow_hidden = True
-# Use advance file ID service for out of band rename support
-c.FileIdExtension.file_id_manager_class = "jupyter_server_fileid.manager.LocalFileIdManager"
diff --git a/binder/postBuild b/binder/postBuild
index aaa4e964..cb36ec80 100755
--- a/binder/postBuild
+++ b/binder/postBuild
@@ -16,9 +16,6 @@ mkdir -p ~/.jupyter/
 
 cp binder/jupyter_config.py ~/.jupyter/
 
-# FIXME until jupyter-server is the default on binder
-cp ${NB_PYTHON_PREFIX}/bin/jupyter-lab ${NB_PYTHON_PREFIX}/bin/jupyter-notebook
-
 jupyter troubleshoot
 jupyter notebook --show-config
 jupyter lab --show-config

From baa56f0efd388e74f1b477badb239ea68f461a07 Mon Sep 17 00:00:00 2001
From: M Bussonnier <bussonniermatthias@gmail.com>
Date: Tue, 10 Feb 2026 10:01:03 +0100
Subject: [PATCH 3/8] setuptools

---
 binder/environment.yml | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/binder/environment.yml b/binder/environment.yml
index f38e4f92..d0797290 100644
--- a/binder/environment.yml
+++ b/binder/environment.yml
@@ -11,5 +11,7 @@ dependencies:
   - hatchling >=1.5.0
   - hatch-jupyter-builder >=0.3.2
   - hatch-nodejs-version
+  # setuptools 82 removed pkg_resources which is needed by pytest_tornado
+  - setuptools < 82.0.0
   # dependencies
   - jupyter_server >=2.0.0

From 3d9498b3083aa91e5b6fa26e83d57a5dc3e2a76f Mon Sep 17 00:00:00 2001
From: M Bussonnier <bussonniermatthias@gmail.com>
Date: Tue, 10 Feb 2026 10:30:55 +0100
Subject: [PATCH 4/8] debug

---
 .github/workflows/tests.yml | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 05bc3bfd..3d3b368a 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -22,7 +22,7 @@ jobs:
         key: ${{ runner.os }}-pip-${{ hashFiles('**/setup.py') }}-${{hashFiles('**/requirements.txt')}}
         restore-keys: |
           ${{ runner.os }}-pip-
-    - name: Install dependencies
+    - name: Install dependencies (docs)
       run: |
         sudo apt-get install -y pandoc
         python -m pip install --upgrade pip
@@ -49,7 +49,7 @@ jobs:
         key: ${{ runner.os }}-pip-${{ hashFiles('**/setup.py') }}-${{hashFiles('**/requirements.txt')}}
         restore-keys: |
           ${{ runner.os }}-pip-
-    - name: Install dependencies
+    - name: Install dependencies (js)
       run: |
         python -m pip install --upgrade pip
 
@@ -116,9 +116,9 @@ jobs:
         key: ${{ runner.os }}-pip-${{ hashFiles('**/setup.py') }}-${{hashFiles('**/requirements.txt')}}
         restore-keys: |
           ${{ runner.os }}-pip-
-    - name: Install dependencies
+    - name: Install dependencies (pytest)
       run: |
-        python -m pip install --upgrade pip
+        python -m pip install --upgrade pip 'setuptools<82'
         python -m pip install jupyterlab~=3.0
         python -m pip install --upgrade --upgrade-strategy=eager ".[test]"
         python -m pip install jupyter_server${{ matrix.jupyter_server-version }}
@@ -213,11 +213,11 @@ jobs:
         path: |
           ${{ github.workspace }}/pw-browsers
         key: ${{ runner.os }}-${{ hashFiles('ui-tests/package-lock.json') }}
-    
+
     - name: Install browser
       working-directory: ui-tests
       run: npx playwright install chromium
-      
+
     - name: Run playwright tests
       working-directory: ui-tests
       run: |

From b40a1f46653183e8e6cfb001fbd534975b71d49e Mon Sep 17 00:00:00 2001
From: M Bussonnier <bussonniermatthias@gmail.com>
Date: Tue, 10 Feb 2026 10:54:16 +0100
Subject: [PATCH 5/8] re-pin setuptools

---
 .github/workflows/tests.yml | 1 +
 1 file changed, 1 insertion(+)

diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 3d3b368a..a2b960a8 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -122,6 +122,7 @@ jobs:
         python -m pip install jupyterlab~=3.0
         python -m pip install --upgrade --upgrade-strategy=eager ".[test]"
         python -m pip install jupyter_server${{ matrix.jupyter_server-version }}
+        python -m pip install 'setuptools<82'
     - name: Test with pytest (Linux)
       if: startsWith(matrix.os, 'ubuntu')
       run: |

From 83f348d04d2b78d734571e6176551e42225178c2 Mon Sep 17 00:00:00 2001
From: M Bussonnier <bussonniermatthias@gmail.com>
Date: Tue, 10 Feb 2026 11:38:25 +0100
Subject: [PATCH 6/8] try to get rid of pytest-tornado (issue with setuptools
 82+)

---
 binder/environment.yml   |  2 --
 nbdime/tests/conftest.py | 31 ++++++++++++++++++++--------
 nbdime/tests/test_web.py | 44 +++++++++++++++++-----------------------
 pyproject.toml           |  1 -
 4 files changed, 42 insertions(+), 36 deletions(-)

diff --git a/binder/environment.yml b/binder/environment.yml
index d0797290..f38e4f92 100644
--- a/binder/environment.yml
+++ b/binder/environment.yml
@@ -11,7 +11,5 @@ dependencies:
   - hatchling >=1.5.0
   - hatch-jupyter-builder >=0.3.2
   - hatch-nodejs-version
-  # setuptools 82 removed pkg_resources which is needed by pytest_tornado
-  - setuptools < 82.0.0
   # dependencies
   - jupyter_server >=2.0.0
diff --git a/nbdime/tests/conftest.py b/nbdime/tests/conftest.py
index aae7374e..93d7df3e 100644
--- a/nbdime/tests/conftest.py
+++ b/nbdime/tests/conftest.py
@@ -10,6 +10,7 @@
 import glob
 import io
 import re
+import threading
 from collections.abc import Sequence
 from subprocess import Popen, TimeoutExpired
 import sys
@@ -220,18 +221,32 @@ def nbdime_base_url():
 
 
 @fixture
-def app(nbdime_base_url, filespath):
-    """This is a fixture used by the pytest-tornado plugin.
-
-    It is indirectly called by all tests that use the `gen_test`
-    test mark.
-    """
+def web_server(nbdime_base_url, filespath):
+    """Start a Tornado web server in a background thread and yield the base URL."""
+    from tornado import ioloop
     from nbdime.webapp.nbdimeserver import init_app
-    return init_app(
+
+    port_holder = {}
+
+    def on_port(port):
+        port_holder['port'] = port
+
+    app, server = init_app(
+        on_port=on_port,
         base_url=nbdime_base_url,
         port=0,
         cwd=filespath,
-    )[0]
+    )
+    loop = ioloop.IOLoop.current()
+    thread = threading.Thread(target=loop.start, daemon=True)
+    thread.start()
+
+    base_url = 'http://localhost:%d' % port_holder['port']
+    yield base_url
+
+    server.stop()
+    loop.add_callback(loop.stop)
+    thread.join(timeout=5)
 
 
 @fixture
diff --git a/nbdime/tests/test_web.py b/nbdime/tests/test_web.py
index 9ebd5fbb..a32cdf1c 100644
--- a/nbdime/tests/test_web.py
+++ b/nbdime/tests/test_web.py
@@ -7,9 +7,9 @@
 import json
 
 import pytest
+import requests
 from tornado import ioloop
 from tornado.httputil import url_concat
-from tornado.escape import json_encode, json_decode
 import nbformat
 
 import nbdime.webapp.nbdiffweb
@@ -73,26 +73,23 @@ def test_merge_web(filespath, unique_port, reset_log, ioloop_patch):
 
 
 @pytest.mark.timeout(timeout=WEB_TEST_TIMEOUT)
-@pytest.mark.gen_test
-def test_fetch_diff(http_client, base_url, nbdime_base_url):
+def test_fetch_diff(web_server, nbdime_base_url):
     url = url_concat(
-        base_url + nbdime_base_url + '/diff',
+        web_server + nbdime_base_url + '/diff',
         dict(base=diff_a, remote=diff_b))
-    response = yield http_client.fetch(url)
-    assert response.code == 200
+    response = requests.get(url)
+    assert response.status_code == 200
 
 
 @pytest.mark.timeout(timeout=WEB_TEST_TIMEOUT)
-@pytest.mark.gen_test
-def test_api_diff(http_client, base_url, nbdime_base_url, diff_validator, filespath, auth_header):
+def test_api_diff(web_server, nbdime_base_url, diff_validator, filespath, auth_header):
     post_data = dict(base=diff_a, remote=diff_b)
-    body = json_encode(post_data)
 
-    url = base_url + nbdime_base_url + '/api/diff'
-    response = yield http_client.fetch(url, method='POST', headers=auth_header, body=body)
-    assert response.code == 200
+    url = web_server + nbdime_base_url + '/api/diff'
+    response = requests.post(url, json=post_data, headers=auth_header)
+    assert response.status_code == 200
     # Check that response is sane:
-    data = json_decode(response.body)
+    data = response.json()
     # Check that base is as expected:
     expected_base = nbformat.read(os.path.join(filespath, diff_a), as_version=4)
     assert json.dumps(data['base'], sort_keys=True) == json.dumps(expected_base, sort_keys=True)
@@ -101,26 +98,23 @@ def test_api_diff(http_client, base_url, nbdime_base_url, diff_validator, filesp
 
 
 @pytest.mark.timeout(timeout=WEB_TEST_TIMEOUT)
-@pytest.mark.gen_test
-def test_fetch_merge(http_client, base_url, nbdime_base_url):
+def test_fetch_merge(web_server, nbdime_base_url):
     url = url_concat(
-        base_url + nbdime_base_url + '/merge',
+        web_server + nbdime_base_url + '/merge',
         dict(base=merge_a, local=merge_b, remote=merge_c))
-    response = yield http_client.fetch(url)
-    assert response.code == 200
+    response = requests.get(url)
+    assert response.status_code == 200
 
 
 @pytest.mark.timeout(timeout=WEB_TEST_TIMEOUT)
-@pytest.mark.gen_test
-def test_api_merge(http_client, base_url, nbdime_base_url, merge_validator, filespath, auth_header):
+def test_api_merge(web_server, nbdime_base_url, merge_validator, filespath, auth_header):
     post_data = dict(base=merge_a, local=merge_b, remote=merge_c)
-    body = json_encode(post_data)
 
-    url = base_url + nbdime_base_url + '/api/merge'
-    response = yield http_client.fetch(url, method='POST', headers=auth_header, body=body)
-    assert response.code == 200
+    url = web_server + nbdime_base_url + '/api/merge'
+    response = requests.post(url, json=post_data, headers=auth_header)
+    assert response.status_code == 200
     # Check that response is sane:
-    data = json_decode(response.body)
+    data = response.json()
     # Check that base is as expected:
     expected_base = nbformat.read(os.path.join(filespath, merge_a), as_version=4)
     assert json.dumps(data['base'], sort_keys=True) == json.dumps(expected_base, sort_keys=True)
diff --git a/pyproject.toml b/pyproject.toml
index 73ab6069..f8ed0cdf 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -71,7 +71,6 @@ test = [
     "pytest>=6.0",
     "pytest-cov",
     "pytest-timeout",
-    "pytest-tornado",
     "jupyter_server[test]",
     "jsonschema",
     "mock",

From 5719bc7c008e2624d11f7def7dc74a0eeef5208e Mon Sep 17 00:00:00 2001
From: M Bussonnier <bussonniermatthias@gmail.com>
Date: Tue, 10 Feb 2026 11:40:49 +0100
Subject: [PATCH 7/8] try another postbuild

---
 binder/postBuild | 63 ++++++++++++++++++++++++++++++++++++------------
 1 file changed, 48 insertions(+), 15 deletions(-)

diff --git a/binder/postBuild b/binder/postBuild
index cb36ec80..87e1a1b1 100755
--- a/binder/postBuild
+++ b/binder/postBuild
@@ -1,23 +1,56 @@
-#!/usr/bin/env bash
+#!/usr/bin/env python3
+""" perform a development install of nbdime
 
-# Copyright (c) Jupyter Development Team.
-# Distributed under the terms of the Modified BSD License.
+    On Binder, this will run _after_ the environment has been fully created from
+    the environment.yml in this directory.
 
-source activate ${NB_PYTHON_PREFIX}
+    This script should also run locally on Linux/MacOS/Windows:
 
-set -euxo pipefail
+        python3 binder/postBuild
+"""
+import subprocess
+import sys
+from pathlib import Path
 
-yarn || yarn
 
-python -m pip install -vv -e . --no-build-isolation
-jupyter server extension enable nbdime
+ROOT = Path.cwd()
 
-mkdir -p ~/.jupyter/
+def _(*args, **kwargs):
+    """ Run a command, echoing the args
 
-cp binder/jupyter_config.py ~/.jupyter/
+        fails hard if something goes wrong
+    """
+    print("\n\t", " ".join(args), "\n")
+    return_code = subprocess.call(args, **kwargs)
+    if return_code != 0:
+        print("\nERROR", return_code, " ".join(args))
+        sys.exit(return_code)
 
-jupyter troubleshoot
-jupyter notebook --show-config
-jupyter lab --show-config
-jupyter labextension list
-jupyter server extension list
+# verify the environment is self-consistent before even starting
+_(sys.executable, "-m", "pip", "check")
+
+# install the labextension
+_(sys.executable, "-m", "pip", "install", "-e", ".")
+_(sys.executable, "-m", "jupyter", "labextension", "develop", "--overwrite", ".")
+_(
+    sys.executable,
+    "-m",
+    "jupyter",
+    "server",
+    "extension",
+    "enable",
+    "{{ python_name }}",
+)
+
+# verify the environment the extension didn't break anything
+_(sys.executable, "-m", "pip", "check")
+
+# list the extensions
+_("jupyter", "server", "extension", "list")
+
+# initially list installed extensions to determine if there are any surprises
+_("jupyter", "labextension", "list")
+
+
+print("JupyterLab with nbdime is ready to run with:\n")
+print("\tjupyter lab\n")

From 9680a5d4b74e27d0202073368d9deabf2ae2d72b Mon Sep 17 00:00:00 2001
From: M Bussonnier <bussonniermatthias@gmail.com>
Date: Tue, 10 Feb 2026 11:44:04 +0100
Subject: [PATCH 8/8] python to bash

---
 binder/postBuild | 81 ++++++++++++++++++++----------------------------
 1 file changed, 33 insertions(+), 48 deletions(-)

diff --git a/binder/postBuild b/binder/postBuild
index 87e1a1b1..5a713a98 100755
--- a/binder/postBuild
+++ b/binder/postBuild
@@ -1,56 +1,41 @@
-#!/usr/bin/env python3
-""" perform a development install of nbdime
-
-    On Binder, this will run _after_ the environment has been fully created from
-    the environment.yml in this directory.
-
-    This script should also run locally on Linux/MacOS/Windows:
-
-        python3 binder/postBuild
-"""
-import subprocess
-import sys
-from pathlib import Path
-
-
-ROOT = Path.cwd()
-
-def _(*args, **kwargs):
-    """ Run a command, echoing the args
-
-        fails hard if something goes wrong
-    """
-    print("\n\t", " ".join(args), "\n")
-    return_code = subprocess.call(args, **kwargs)
-    if return_code != 0:
-        print("\nERROR", return_code, " ".join(args))
-        sys.exit(return_code)
+#!/usr/bin/env bash
+# perform a development install of nbdime
+#
+#   On Binder, this will run _after_ the environment has been fully created from
+#   the environment.yml in this directory.
+#
+#   This script should also run locally on Linux/MacOS:
+#
+#       bash binder/postBuild
+
+set -euox pipefail
 
 # verify the environment is self-consistent before even starting
-_(sys.executable, "-m", "pip", "check")
+pip check
 
 # install the labextension
-_(sys.executable, "-m", "pip", "install", "-e", ".")
-_(sys.executable, "-m", "jupyter", "labextension", "develop", "--overwrite", ".")
-_(
-    sys.executable,
-    "-m",
-    "jupyter",
-    "server",
-    "extension",
-    "enable",
-    "{{ python_name }}",
-)
-
-# verify the environment the extension didn't break anything
-_(sys.executable, "-m", "pip", "check")
+pip install -e .
+jupyter labextension develop --overwrite .
+jupyter server extension enable nbdime
 
-# list the extensions
-_("jupyter", "server", "extension", "list")
+#
+mkdir -p ~/.jupyter/
 
-# initially list installed extensions to determine if there are any surprises
-_("jupyter", "labextension", "list")
+cp binder/jupyter_config.py ~/.jupyter/
 
+# verify the extension didn't break anything
+pip check
 
-print("JupyterLab with nbdime is ready to run with:\n")
-print("\tjupyter lab\n")
+# list the extensions
+jupyter troubleshoot
+jupyter notebook --show-config
+jupyter lab --show-config
+jupyter server extension list
+jupyter labextension list
+
+
+echo ""
+echo "JupyterLab with nbdime is ready to run with:"
+echo ""
+echo "    jupyter lab"
+echo ""