diff --git a/.coveragerc b/.coveragerc
new file mode 100644
index 0000000..1f2be51
--- /dev/null
+++ b/.coveragerc
@@ -0,0 +1,15 @@
+[run]
+# All files under source are checked, even if not otherwise referenced.
+source = .
+
+omit =
+  # TODO
+  app.py
+
+# More strict: Check transitions between lines, not just individual lines.
+# TODO: branch = True
+
+[report]
+show_missing = True
+skip_covered = True
+fail_under = 100
diff --git a/.flake8 b/.flake8
new file mode 100644
index 0000000..5ecd0d5
--- /dev/null
+++ b/.flake8
@@ -0,0 +1,12 @@
+[flake8]
+exclude = .git,.venv,__pycache__
+
+# Config recommended by black:
+# https://black.readthedocs.io/en/stable/guides/using_black_with_other_tools.html#bugbear
+max-line-length = 80
+extend-select = B950
+extend-ignore = E203,E501,E701
+
+per-file-ignores =
+    # Ignore undefined names
+    */templates/*:F821,F401
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
new file mode 100644
index 0000000..ecc48ab
--- /dev/null
+++ b/.github/workflows/test.yml
@@ -0,0 +1,47 @@
+name: Test
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+jobs:
+  test:
+    runs-on: ubuntu-22.04
+    strategy:
+      matrix:
+        python-version:
+          - '3.9'
+          - '3.12'
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python-version }}
+
+      - name: Install flit
+        run: pip install flit
+
+      - name: Install package
+        run: flit install
+
+      - name: Check CLI
+        # TODO: This won't catch most missing dependencies.
+        run: dp-creator-ii --help
+
+      - name: Install dev dependencies
+        run: pip install -r requirements-dev.txt
+
+      - name: Install browsers
+        run: playwright install
+
+      - name: Test
+        run: coverage run -m pytest -v
+
+      - name: Check coverage
+        run: coverage report
diff --git a/.mypy.ini b/.mypy.ini
new file mode 100644
index 0000000..16faf59
--- /dev/null
+++ b/.mypy.ini
@@ -0,0 +1,5 @@
+[mypy]
+exclude = '\.venv'
+
+# TODO: Ignore undefined names only in templates. 
+disable_error_code = name-defined
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
new file mode 100644
index 0000000..d07faf4
--- /dev/null
+++ b/.pre-commit-config.yaml
@@ -0,0 +1,17 @@
+repos:
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v2.3.0
+    hooks:
+    -   id: check-yaml
+    -   id: end-of-file-fixer
+    -   id: trailing-whitespace
+  # Using this mirror lets us use mypyc-compiled black, which is about 2x faster
+  - repo: https://github.com/psf/black-pre-commit-mirror
+    rev: 24.8.0
+    hooks:
+      - id: black
+        # It is recommended to specify the latest version of Python
+        # supported by your project here, or alternatively use
+        # pre-commit's default_language_version, see
+        # https://pre-commit.com/#top_level-default_language_version
+        language_version: python3.11
diff --git a/README.md b/README.md
index f3ab36a..925c4bd 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,6 @@
 # DP Creator II
 
-** Under Construction **
+**Under Construction**
 
 Building on what we've learned from [DP Creator](https://github.com/opendp/dpcreator), DP Creator II will offer:
 
@@ -10,3 +10,56 @@ Building on what we've learned from [DP Creator](https://github.com/opendp/dpcre
 - Interactive visualization of privacy budget choices
 - UI development in Python with [Shiny](https://shiny.posit.co/py/)
 - Tracking of cumulative privacy consumption between sessions
+
+## Usage
+
+```
+usage: dp-creator-ii [-h] [--csv CSV_PATH] [--unit UNIT_OF_PRIVACY] [--debug]
+
+DP Creator II makes it easier to get started with Differential Privacy.
+
+options:
+  -h, --help            show this help message and exit
+  --csv CSV_PATH        Path to CSV containing private data
+  --unit UNIT_OF_PRIVACY
+                        Unit of privacy: How many rows can an individual
+                        contribute?
+  --debug               Use during development for increased logging and auto-
+                        reload after code changes
+```
+
+
+## Development
+
+### Getting Started
+
+To get started, clone the repo and install dev dependencies in a virtual environment:
+```
+git clone https://github.com/opendp/dp-creator-ii.git
+cd dp-creator-ii
+python3 -m venv .venv
+source .venv/bin/activate
+pip install -r requirements-dev.txt
+pre-commit install
+playwright install
+```
+
+Now install the application itself and run it:
+```
+flit install --symlink
+dp-creator-ii
+```
+Your browser should open and connect you to the application.
+
+Tests should pass, and code coverage should be complete (except blocks we explicitly ignore):
+```
+coverage run -m pytest -v
+coverage report
+```
+
+### Conventions
+
+Branch names should be of the form `NNNN-short-description`, where `NNNN` is the issue number being addressed.
+
+Dependencies should be pinned for development, but not pinned when the package is installed.
+New dev dependencies can be added to `requirements-dev.in`, and then run `pip-compile requirements-dev.in` to update `requirements-dev.txt`
diff --git a/dp_creator_ii/.gitignore b/dp_creator_ii/.gitignore
new file mode 100644
index 0000000..0cffcb3
--- /dev/null
+++ b/dp_creator_ii/.gitignore
@@ -0,0 +1 @@
+config.json
\ No newline at end of file
diff --git a/dp_creator_ii/__init__.py b/dp_creator_ii/__init__.py
new file mode 100644
index 0000000..be09255
--- /dev/null
+++ b/dp_creator_ii/__init__.py
@@ -0,0 +1,62 @@
+"""DP Creator II makes it easier to get started with Differential Privacy."""
+
+import os
+from pathlib import Path
+from argparse import ArgumentParser
+import json
+
+import shiny
+
+
+__version__ = "0.0.1"
+
+
+def get_parser():
+    parser = ArgumentParser(description=__doc__)
+    parser.add_argument(
+        "--csv",
+        dest="csv_path",
+        type=Path,
+        help="Path to CSV containing private data",
+    )
+    parser.add_argument(
+        "--unit",
+        dest="unit_of_privacy",
+        type=int,
+        help="Unit of privacy: How many rows can an individual contribute?",
+    )
+    parser.add_argument(
+        "--debug",
+        action="store_true",
+        help="Use during development for increased logging "
+        "and auto-reload after code changes",
+    )
+    return parser
+
+
+def main():  # pragma: no cover
+    parser = get_parser()
+    args = parser.parse_args()
+
+    os.chdir(Path(__file__).parent)  # run_app() depends on the CWD.
+
+    # Just setting variables in a plain python module doesn't work:
+    # The new thread started for the server doesn't see changes.
+    Path("config.json").write_text(
+        json.dumps(
+            {
+                "csv_path": str(args.csv_path),
+                "unit_of_privacy": args.unit_of_privacy,
+            }
+        )
+    )
+
+    run_app_kwargs = (
+        {}
+        if not args.debug
+        else {
+            "reload": True,
+            "log_level": "debug",
+        }
+    )
+    shiny.run_app(launch_browser=True, **run_app_kwargs)
diff --git a/dp_creator_ii/app.py b/dp_creator_ii/app.py
new file mode 100644
index 0000000..e3bb1ec
--- /dev/null
+++ b/dp_creator_ii/app.py
@@ -0,0 +1,124 @@
+import json
+from pathlib import Path
+
+from shiny import App, ui, reactive, render
+
+from dp_creator_ii.template import make_notebook_py, make_script_py
+from dp_creator_ii.converters import convert_py_to_nb
+
+
+def dataset_panel():
+    return ui.nav_panel(
+        "Select Dataset",
+        "TODO: Pick dataset",
+        ui.output_text("csv_path_text"),
+        ui.output_text("unit_of_privacy_text"),
+        ui.input_action_button("go_to_analysis", "Perform analysis"),
+        value="dataset_panel",
+    )
+
+
+def analysis_panel():
+    return ui.nav_panel(
+        "Perform Analysis",
+        "TODO: Define analysis",
+        ui.input_action_button("go_to_results", "Download results"),
+        value="analysis_panel",
+    )
+
+
+def results_panel():
+    return ui.nav_panel(
+        "Download Results",
+        "TODO: Download Results",
+        ui.download_button("download_script", "Download script"),
+        # TODO: Notebook code is badly formatted
+        # ui.download_button(
+        #     "download_notebook_unexecuted", "Download notebook (unexecuted)"
+        # ),
+        # ui.download_button(
+        #     "download_notebook_executed", "Download notebook (executed)"
+        # )
+        value="results_panel",
+    )
+
+
+app_ui = ui.page_bootstrap(
+    ui.navset_tab(
+        dataset_panel(),
+        analysis_panel(),
+        results_panel(),
+        id="top_level_nav",
+    ),
+    title="DP Creator II",
+)
+
+
+def server(input, output, session):
+    config_path = Path(__file__).parent / "config.json"
+    config = json.loads(config_path.read_text())
+    config_path.unlink()
+
+    csv_path = reactive.value(config["csv_path"])
+    unit_of_privacy = reactive.value(config["unit_of_privacy"])
+
+    @render.text
+    def csv_path_text():
+        return str(csv_path.get())
+
+    @render.text
+    def unit_of_privacy_text():
+        return str(unit_of_privacy.get())
+
+    @reactive.effect
+    @reactive.event(input.go_to_analysis)
+    def go_to_analysis():
+        ui.update_navs("top_level_nav", selected="analysis_panel")
+
+    @reactive.effect
+    @reactive.event(input.go_to_results)
+    def go_to_results():
+        ui.update_navs("top_level_nav", selected="results_panel")
+
+    @render.download(
+        filename="dp-creator-script.py",
+        media_type="text/x-python",
+    )
+    async def download_script():
+        script_py = make_script_py(
+            unit=1,
+            loss=1,
+            weights=[1],
+        )
+        yield script_py
+
+    @render.download(
+        filename="dp-creator-notebook.ipynb",
+        media_type="application/x-ipynb+json",
+    )
+    async def download_notebook_unexecuted():
+        notebook_py = make_notebook_py(
+            csv_path="todo.csv",
+            unit=1,
+            loss=1,
+            weights=[1],
+        )
+        notebook_nb = convert_py_to_nb(notebook_py)
+        yield notebook_nb
+
+    @render.download(
+        filename="dp-creator-notebook-executed.ipynb",
+        media_type="application/x-ipynb+json",
+    )
+    async def download_notebook_executed():
+        notebook_py = make_notebook_py(
+            csv_path="todo.csv",
+            unit=1,
+            loss=1,
+            weights=[1],
+        )
+        notebook_nb = convert_py_to_nb(notebook_py, execute=True)
+        yield notebook_nb
+
+
+app = App(app_ui, server)
diff --git a/dp_creator_ii/converters.py b/dp_creator_ii/converters.py
new file mode 100644
index 0000000..d5dcee1
--- /dev/null
+++ b/dp_creator_ii/converters.py
@@ -0,0 +1,41 @@
+from pathlib import Path
+from tempfile import TemporaryDirectory
+import subprocess
+
+
+def convert_py_to_nb(python_str, execute=False):
+    """
+    Given Python code as a string, returns a notebook as a string.
+    Calls jupytext as a subprocess:
+    Not ideal, but only the CLI is documented well.
+    """
+    with TemporaryDirectory() as temp_dir:
+        temp_dir_path = Path(temp_dir)
+        py_path = temp_dir_path / "input.py"
+        py_path.write_text(python_str)
+        nb_path = temp_dir_path / "output.ipynb"
+        argv = (
+            [
+                "jupytext",
+                "--to",
+                "ipynb",  # Target format
+                "--output",
+                nb_path.absolute(),  # Output
+            ]
+            + (["--execute"] if execute else [])
+            + [py_path.absolute()]  # Input
+        )
+        try:
+            subprocess.run(argv, check=True)
+        except subprocess.CalledProcessError:  # pragma: no cover
+            if not execute:
+                raise
+            # Install kernel if missing
+            # TODO: Is there a better way to do this?
+            subprocess.run(
+                "python -m ipykernel install --name kernel_name --user".split(" "),
+                check=True,
+            )
+            subprocess.run(argv, check=True)
+
+        return nb_path.read_text()
diff --git a/dp_creator_ii/template.py b/dp_creator_ii/template.py
new file mode 100644
index 0000000..91ad658
--- /dev/null
+++ b/dp_creator_ii/template.py
@@ -0,0 +1,112 @@
+from pathlib import Path
+import re
+from functools import partial
+
+
+def match_indent_maker(v):
+    # Working around late binding closure in loop:
+    # https://docs.python-guide.org/writing/gotchas/#late-binding-closures
+    # Would like a simpler solution.
+    def match_indent(match):
+        return "\n".join(match.group(1) + line for line in v.split("\n"))
+
+    return match_indent
+
+
+class _Template:
+    def __init__(self, path):
+        self._path = path
+        template_path = Path(__file__).parent / "templates" / path
+        self._template = template_path.read_text()
+
+    def fill_expressions(self, map):
+        for k, v in map.items():
+            self._template = self._template.replace(k, v)
+        return self
+
+    def fill_values(self, map):
+        for k, v in map.items():
+            self._template = self._template.replace(k, repr(v))
+        return self
+
+    def fill_blocks(self, map):
+        for k, v in map.items():
+            k_re = re.escape(k)
+            self._template = re.sub(
+                rf"^(\s*){k_re}$",
+                partial(match_indent_maker, v)(),
+                self._template,
+                flags=re.MULTILINE,
+            )
+        return self
+
+    def __str__(self):
+        unfilled = set(re.findall(r"[A-Z][A-Z_]+", self._template))
+        if unfilled:
+            raise Exception(
+                f"Template {self._path} has unfilled slots: "
+                f'{", ".join(sorted(unfilled))}\n\n{self._template}'
+            )
+        return self._template
+
+
+def _make_context_for_notebook(csv_path, unit, loss, weights):
+    return str(
+        _Template("context.py").fill_values(
+            {
+                "CSV_PATH": csv_path,
+                "UNIT": unit,
+                "LOSS": loss,
+                "WEIGHTS": weights,
+            }
+        )
+    )
+
+
+def _make_context_for_script(unit, loss, weights):
+    return str(
+        _Template("context.py")
+        .fill_expressions({"CSV_PATH": "csv_path"})
+        .fill_values(
+            {
+                "UNIT": unit,
+                "LOSS": loss,
+                "WEIGHTS": weights,
+            }
+        )
+    )
+
+
+def _make_imports():
+    return str(_Template("imports.py").fill_values({}))
+
+
+def make_notebook_py(csv_path, unit, loss, weights):
+    return str(
+        _Template("notebook.py").fill_blocks(
+            {
+                "IMPORTS_BLOCK": _make_imports(),
+                "CONTEXT_BLOCK": _make_context_for_notebook(
+                    csv_path=csv_path,
+                    unit=unit,
+                    loss=loss,
+                    weights=weights,
+                ),
+            }
+        )
+    )
+
+
+def make_script_py(unit, loss, weights):
+    return str(
+        _Template("script.py").fill_blocks(
+            {
+                "IMPORTS_BLOCK": _make_imports(),
+                "CONTEXT_BLOCK": _make_context_for_script(
+                    unit=unit,
+                    loss=loss,
+                    weights=weights,
+                ),
+            }
+        )
+    )
diff --git a/dp_creator_ii/templates/README.md b/dp_creator_ii/templates/README.md
new file mode 100644
index 0000000..8d6618c
--- /dev/null
+++ b/dp_creator_ii/templates/README.md
@@ -0,0 +1 @@
+Strings of ALL CAPS are replaced in these templates. Keeping them in a format which can actually be parsed as python makes some things easier, but it is also reinventing the wheel. We may revisit this.
\ No newline at end of file
diff --git a/dp_creator_ii/templates/context.py b/dp_creator_ii/templates/context.py
new file mode 100644
index 0000000..b970a75
--- /dev/null
+++ b/dp_creator_ii/templates/context.py
@@ -0,0 +1,6 @@
+context = dp.Context.compositor(
+    data=pl.scan_csv(CSV_PATH),
+    privacy_unit=dp.unit_of(contributions=UNIT),
+    privacy_loss=dp.loss_of(epsilon=LOSS),
+    split_by_weights=WEIGHTS,
+)
diff --git a/dp_creator_ii/templates/imports.py b/dp_creator_ii/templates/imports.py
new file mode 100644
index 0000000..5df8d79
--- /dev/null
+++ b/dp_creator_ii/templates/imports.py
@@ -0,0 +1,4 @@
+import polars as pl
+import opendp.prelude as dp
+
+dp.enable_features("contrib")
diff --git a/dp_creator_ii/templates/notebook.py b/dp_creator_ii/templates/notebook.py
new file mode 100644
index 0000000..1eb6702
--- /dev/null
+++ b/dp_creator_ii/templates/notebook.py
@@ -0,0 +1,4 @@
+IMPORTS_BLOCK
+
+CONTEXT_BLOCK
+print(context)
diff --git a/dp_creator_ii/templates/script.py b/dp_creator_ii/templates/script.py
new file mode 100644
index 0000000..37be6c5
--- /dev/null
+++ b/dp_creator_ii/templates/script.py
@@ -0,0 +1,18 @@
+from argparse import ArgumentParser
+
+IMPORTS_BLOCK
+
+
+def get_context(csv_path):
+    CONTEXT_BLOCK
+    return context
+
+
+if __name__ == "__main__":
+    parser = ArgumentParser(
+        description="Creates a differentially private release from a csv"
+    )
+    parser.add_argument("--csv", help="Path to csv containing private data")
+    args = parser.parse_args()
+    context = get_context(csv_path=args.csv)
+    print(context)
diff --git a/dp_creator_ii/tests/fixtures/fake-executed.ipynb b/dp_creator_ii/tests/fixtures/fake-executed.ipynb
new file mode 100644
index 0000000..21678c5
--- /dev/null
+++ b/dp_creator_ii/tests/fixtures/fake-executed.ipynb
@@ -0,0 +1,69 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "id": "d68beaaf",
+   "metadata": {},
+   "source": [
+    "Introduction"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "id": "c4a24010",
+   "metadata": {
+    "execution": {
+     "iopub.execute_input": "2024-09-24T22:01:27.184792Z",
+     "iopub.status.busy": "2024-09-24T22:01:27.184540Z",
+     "iopub.status.idle": "2024-09-24T22:01:27.188766Z",
+     "shell.execute_reply": "2024-09-24T22:01:27.188362Z"
+    }
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "4\n"
+     ]
+    }
+   ],
+   "source": [
+    "print(2 + 2)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "aa6d5643",
+   "metadata": {},
+   "source": [
+    "Conclusion"
+   ]
+  }
+ ],
+ "metadata": {
+  "jupytext": {
+   "cell_metadata_filter": "-all"
+  },
+  "kernelspec": {
+   "display_name": "kernel_name",
+   "language": "python",
+   "name": "kernel_name"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.12.3"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 5
+}
diff --git a/dp_creator_ii/tests/fixtures/fake.csv b/dp_creator_ii/tests/fixtures/fake.csv
new file mode 100644
index 0000000..4393e1a
--- /dev/null
+++ b/dp_creator_ii/tests/fixtures/fake.csv
@@ -0,0 +1 @@
+fake-column
\ No newline at end of file
diff --git a/dp_creator_ii/tests/fixtures/fake.ipynb b/dp_creator_ii/tests/fixtures/fake.ipynb
new file mode 100644
index 0000000..a8aff92
--- /dev/null
+++ b/dp_creator_ii/tests/fixtures/fake.ipynb
@@ -0,0 +1,42 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "id": "3cf946cc",
+   "metadata": {},
+   "source": [
+    "Introduction"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "d5a25047",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "print(2 + 2)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "08581071",
+   "metadata": {},
+   "source": [
+    "Conclusion"
+   ]
+  }
+ ],
+ "metadata": {
+  "jupytext": {
+   "cell_metadata_filter": "-all",
+   "main_language": "python",
+   "notebook_metadata_filter": "-all"
+  },
+  "language_info": {
+   "name": "python"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 5
+}
diff --git a/dp_creator_ii/tests/fixtures/fake.py b/dp_creator_ii/tests/fixtures/fake.py
new file mode 100644
index 0000000..64636ab
--- /dev/null
+++ b/dp_creator_ii/tests/fixtures/fake.py
@@ -0,0 +1,5 @@
+# Introduction
+
+print(2 + 2)
+
+# Conclusion
diff --git a/dp_creator_ii/tests/test_app.py b/dp_creator_ii/tests/test_app.py
new file mode 100644
index 0000000..ec1ea58
--- /dev/null
+++ b/dp_creator_ii/tests/test_app.py
@@ -0,0 +1,13 @@
+from shiny.run import ShinyAppProc
+from playwright.sync_api import Page, expect
+from shiny.pytest import create_app_fixture
+
+
+app = create_app_fixture("../app.py")
+
+
+# TODO: Why is incomplete coverage reported here?
+def test_app(page: Page, app: ShinyAppProc):  # pragma: no cover
+    page.goto(app.url)
+    expect(page).to_have_title("DP Creator II")
+    expect(page.locator("body")).to_contain_text("TODO: Pick dataset")
diff --git a/dp_creator_ii/tests/test_converters.py b/dp_creator_ii/tests/test_converters.py
new file mode 100644
index 0000000..408c267
--- /dev/null
+++ b/dp_creator_ii/tests/test_converters.py
@@ -0,0 +1,40 @@
+import re
+from pathlib import Path
+from dp_creator_ii.converters import convert_py_to_nb
+
+
+def norm_nb(nb_str):
+    normed_nb_str = nb_str
+    normed_nb_str = re.sub(r'"id": "[^"]+"', '"id": "12345678"', normed_nb_str)
+    normed_nb_str = re.sub(
+        r"\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}\.\d+Z",
+        "2024-01-01T00:00:00.000000Z",
+        normed_nb_str,
+    )
+    # language_info added when saved by VSCode:
+    normed_nb_str = re.sub(r',\s+"language_info": \{[^}]*\}', "", normed_nb_str)
+    # version will be different between dev environment and CI:
+    normed_nb_str = re.sub(r'"version": "[^"]+"', '"version": "3.0.0"', normed_nb_str)
+    return normed_nb_str
+
+
+def test_convert_py_to_nb():
+    fixtures_path = Path("dp_creator_ii/tests/fixtures")
+    python_str = (fixtures_path / "fake.py").read_text()
+    actual_nb_str = convert_py_to_nb(python_str)
+    expected_nb_str = (fixtures_path / "fake.ipynb").read_text()
+
+    normed_actual_nb_str = norm_nb(actual_nb_str)
+    normed_expected_nb_str = norm_nb(expected_nb_str)
+    assert normed_actual_nb_str == normed_expected_nb_str
+
+
+def test_convert_py_to_nb_execute():
+    fixtures_path = Path("dp_creator_ii/tests/fixtures")
+    python_str = (fixtures_path / "fake.py").read_text()
+    actual_nb_str = convert_py_to_nb(python_str, execute=True)
+    expected_nb_str = (fixtures_path / "fake-executed.ipynb").read_text()
+
+    normed_actual_nb_str = norm_nb(actual_nb_str)
+    normed_expected_nb_str = norm_nb(expected_nb_str)
+    assert normed_actual_nb_str == normed_expected_nb_str
diff --git a/dp_creator_ii/tests/test_help.py b/dp_creator_ii/tests/test_help.py
new file mode 100644
index 0000000..6752325
--- /dev/null
+++ b/dp_creator_ii/tests/test_help.py
@@ -0,0 +1,20 @@
+from pathlib import Path
+
+import dp_creator_ii
+
+
+def test_help():
+    help = (
+        dp_creator_ii.get_parser()
+        .format_help()
+        # argparse doesn't actually know the name of the script
+        # and inserts the name of the running program instead.
+        .replace("__main__.py", "dp-creator-ii")
+        .replace("pytest", "dp-creator-ii")
+        # Text is different under Python 3.9:
+        .replace("optional arguments:", "options:")
+    )
+    print(help)
+
+    readme_md = (Path(__file__).parent.parent.parent / "README.md").read_text()
+    assert help in readme_md
diff --git a/dp_creator_ii/tests/test_misc.py b/dp_creator_ii/tests/test_misc.py
new file mode 100644
index 0000000..d7cbede
--- /dev/null
+++ b/dp_creator_ii/tests/test_misc.py
@@ -0,0 +1,14 @@
+import subprocess
+import pytest
+
+
+tests = {
+    "flake8 linting": "flake8 . --count --show-source --statistics",
+    "mypy type checking": "mypy .",
+}
+
+
+@pytest.mark.parametrize("cmd", tests.values(), ids=tests.keys())
+def test_subprocess(cmd):
+    result = subprocess.run(cmd, shell=True)
+    assert result.returncode == 0, f'"{cmd}" failed'
diff --git a/dp_creator_ii/tests/test_template.py b/dp_creator_ii/tests/test_template.py
new file mode 100644
index 0000000..dd53b55
--- /dev/null
+++ b/dp_creator_ii/tests/test_template.py
@@ -0,0 +1,60 @@
+from tempfile import NamedTemporaryFile
+import subprocess
+import re
+import pytest
+import opendp.prelude as dp
+from dp_creator_ii.template import _Template, make_notebook_py, make_script_py
+
+
+fake_csv = "dp_creator_ii/tests/fixtures/fake.csv"
+
+
+def test_fill_template():
+    context_template = _Template("context.py")
+    context_block = str(
+        context_template.fill_values(
+            {
+                "CSV_PATH": fake_csv,
+                "UNIT": 1,
+                "LOSS": 1,
+                "WEIGHTS": [1],
+            }
+        )
+    )
+    assert f"data=pl.scan_csv('{fake_csv}')" in context_block
+
+
+def test_fill_template_unfilled_slots():
+    context_template = _Template("context.py")
+    with pytest.raises(
+        Exception,
+        match=re.escape("context.py has unfilled slots: CSV_PATH, LOSS, UNIT, WEIGHTS"),
+    ):
+        str(context_template.fill_values({}))
+
+
+def test_make_notebook():
+    notebook = make_notebook_py(
+        csv_path=fake_csv,
+        unit=1,
+        loss=1,
+        weights=[1],
+    )
+    globals = {}
+    exec(notebook, globals)
+    assert isinstance(globals["context"], dp.Context)
+
+
+def test_make_script():
+    script = make_script_py(
+        unit=1,
+        loss=1,
+        weights=[1],
+    )
+
+    with NamedTemporaryFile(mode="w", delete=False) as fp:
+        fp.write(script)
+        fp.close()
+
+        result = subprocess.run(["python", fp.name, "--csv", fake_csv])
+        assert result.returncode == 0
diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 0000000..59751d1
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,26 @@
+[build-system]
+requires = ["flit_core >=3.2,<4"]
+build-backend = "flit_core.buildapi"
+
+[project]
+name = "dp_creator_ii"
+authors = [{name = "Chuck McCallum", email = "mccallucc@gmail.com"}]
+readme = "README.md"
+license = {file = "LICENSE"}
+classifiers = ["License :: OSI Approved :: MIT License"]
+dynamic = ["version", "description"]
+dependencies = [
+    "shiny",
+    "shinywidgets",
+    "opendp[polars]",
+    "jupytext",
+    "jupyter-client",
+    "nbconvert",
+    "ipykernel",
+]
+
+[project.scripts]
+dp-creator-ii = "dp_creator_ii:main"
+
+[project.urls]
+Home = "https://github.com/opendp/dp-creator-ii"
diff --git a/requirements-dev.in b/requirements-dev.in
new file mode 100644
index 0000000..f2eb714
--- /dev/null
+++ b/requirements-dev.in
@@ -0,0 +1,37 @@
+# After making changes here, run:
+#    pip-compile requirements-dev.in && pip install -r requirements-dev.txt
+
+# Developer tools:
+pip-tools
+flit
+black
+flake8
+flake8-bugbear
+pre-commit
+
+# Testing:
+pytest
+pytest-playwright
+mypy
+coverage
+
+
+
+# Everything below should also be listed in pyproject.toml:
+
+# OpenDP:
+opendp[polars]
+# For Python 3.9:
+scipy<1.14
+
+# Conversion:
+jupytext
+jupyter-client
+nbconvert
+ipykernel
+# May also require:
+# python -m ipykernel install --name kernel_name --user
+
+# Shiny:
+shiny
+shinywidgets
diff --git a/requirements-dev.txt b/requirements-dev.txt
new file mode 100644
index 0000000..7916b16
--- /dev/null
+++ b/requirements-dev.txt
@@ -0,0 +1,361 @@
+#
+# This file is autogenerated by pip-compile with Python 3.12
+# by the following command:
+#
+#    pip-compile requirements-dev.in
+#
+anyio==4.4.0
+    # via
+    #   starlette
+    #   watchfiles
+appdirs==1.4.4
+    # via shiny
+appnope==0.1.4
+    # via ipykernel
+asgiref==3.8.1
+    # via shiny
+asttokens==2.4.1
+    # via stack-data
+attrs==24.2.0
+    # via
+    #   flake8-bugbear
+    #   jsonschema
+    #   referencing
+beautifulsoup4==4.12.3
+    # via nbconvert
+black==24.8.0
+    # via -r requirements-dev.in
+bleach==6.1.0
+    # via nbconvert
+build==1.2.2
+    # via pip-tools
+certifi==2024.8.30
+    # via requests
+cfgv==3.4.0
+    # via pre-commit
+charset-normalizer==3.3.2
+    # via requests
+click==8.1.7
+    # via
+    #   black
+    #   pip-tools
+    #   shiny
+    #   uvicorn
+comm==0.2.2
+    # via
+    #   ipykernel
+    #   ipywidgets
+coverage==7.6.1
+    # via -r requirements-dev.in
+debugpy==1.8.6
+    # via ipykernel
+decorator==5.1.1
+    # via ipython
+defusedxml==0.7.1
+    # via nbconvert
+distlib==0.3.8
+    # via virtualenv
+docutils==0.21.2
+    # via flit
+executing==2.1.0
+    # via stack-data
+fastjsonschema==2.20.0
+    # via nbformat
+filelock==3.16.1
+    # via virtualenv
+flake8==7.1.1
+    # via
+    #   -r requirements-dev.in
+    #   flake8-bugbear
+flake8-bugbear==24.8.19
+    # via -r requirements-dev.in
+flit==3.9.0
+    # via -r requirements-dev.in
+flit-core==3.9.0
+    # via flit
+greenlet==3.0.3
+    # via playwright
+h11==0.14.0
+    # via uvicorn
+htmltools==0.5.3
+    # via shiny
+identify==2.6.1
+    # via pre-commit
+idna==3.10
+    # via
+    #   anyio
+    #   requests
+iniconfig==2.0.0
+    # via pytest
+ipykernel==6.29.5
+    # via -r requirements-dev.in
+ipython==8.18.0
+    # via
+    #   ipykernel
+    #   ipywidgets
+ipywidgets==8.1.5
+    # via shinywidgets
+jedi==0.19.1
+    # via ipython
+jinja2==3.1.4
+    # via nbconvert
+joblib==1.4.2
+    # via scikit-learn
+jsonschema==4.23.0
+    # via nbformat
+jsonschema-specifications==2023.12.1
+    # via jsonschema
+jupyter-client==8.6.3
+    # via
+    #   -r requirements-dev.in
+    #   ipykernel
+    #   nbclient
+jupyter-core==5.7.2
+    # via
+    #   ipykernel
+    #   jupyter-client
+    #   nbclient
+    #   nbconvert
+    #   nbformat
+    #   shinywidgets
+jupyterlab-pygments==0.3.0
+    # via nbconvert
+jupyterlab-widgets==3.0.13
+    # via ipywidgets
+jupytext==1.16.4
+    # via -r requirements-dev.in
+linkify-it-py==2.0.3
+    # via shiny
+markdown-it-py==3.0.0
+    # via
+    #   jupytext
+    #   mdit-py-plugins
+    #   shiny
+markupsafe==2.1.5
+    # via
+    #   jinja2
+    #   nbconvert
+matplotlib-inline==0.1.7
+    # via
+    #   ipykernel
+    #   ipython
+mccabe==0.7.0
+    # via flake8
+mdit-py-plugins==0.4.2
+    # via
+    #   jupytext
+    #   shiny
+mdurl==0.1.2
+    # via markdown-it-py
+mistune==3.0.2
+    # via nbconvert
+mypy==1.11.2
+    # via -r requirements-dev.in
+mypy-extensions==1.0.0
+    # via
+    #   black
+    #   mypy
+nbclient==0.10.0
+    # via nbconvert
+nbconvert==7.16.4
+    # via -r requirements-dev.in
+nbformat==5.10.4
+    # via
+    #   jupytext
+    #   nbclient
+    #   nbconvert
+nest-asyncio==1.6.0
+    # via ipykernel
+nodeenv==1.9.1
+    # via pre-commit
+numpy==1.26.4
+    # via
+    #   opendp
+    #   pyarrow
+    #   randomgen
+    #   scikit-learn
+    #   scipy
+opendp[polars]==0.11.1
+    # via -r requirements-dev.in
+packaging==24.1
+    # via
+    #   black
+    #   build
+    #   htmltools
+    #   ipykernel
+    #   jupytext
+    #   nbconvert
+    #   pytest
+    #   shiny
+pandocfilters==1.5.1
+    # via nbconvert
+parso==0.8.4
+    # via jedi
+pathspec==0.12.1
+    # via black
+pexpect==4.9.0
+    # via ipython
+pip-tools==7.4.1
+    # via -r requirements-dev.in
+platformdirs==4.3.6
+    # via
+    #   black
+    #   jupyter-core
+    #   virtualenv
+playwright==1.47.0
+    # via pytest-playwright
+pluggy==1.5.0
+    # via pytest
+polars==1.1.0
+    # via opendp
+pre-commit==3.8.0
+    # via -r requirements-dev.in
+prompt-toolkit==3.0.36
+    # via
+    #   ipython
+    #   questionary
+    #   shiny
+psutil==6.0.0
+    # via ipykernel
+ptyprocess==0.7.0
+    # via pexpect
+pure-eval==0.2.3
+    # via stack-data
+pyarrow==17.0.0
+    # via opendp
+pycodestyle==2.12.1
+    # via flake8
+pyee==12.0.0
+    # via playwright
+pyflakes==3.2.0
+    # via flake8
+pygments==2.18.0
+    # via
+    #   ipython
+    #   nbconvert
+pyproject-hooks==1.1.0
+    # via
+    #   build
+    #   pip-tools
+pytest==8.3.3
+    # via
+    #   -r requirements-dev.in
+    #   pytest-base-url
+    #   pytest-playwright
+pytest-base-url==2.1.0
+    # via pytest-playwright
+pytest-playwright==0.5.2
+    # via -r requirements-dev.in
+python-dateutil==2.9.0.post0
+    # via
+    #   jupyter-client
+    #   shinywidgets
+python-multipart==0.0.9
+    # via shiny
+python-slugify==8.0.4
+    # via pytest-playwright
+pyyaml==6.0.2
+    # via
+    #   jupytext
+    #   pre-commit
+pyzmq==26.2.0
+    # via
+    #   ipykernel
+    #   jupyter-client
+questionary==2.0.1
+    # via shiny
+randomgen==2.0.1
+    # via opendp
+referencing==0.35.1
+    # via
+    #   jsonschema
+    #   jsonschema-specifications
+requests==2.32.3
+    # via
+    #   flit
+    #   pytest-base-url
+rpds-py==0.20.0
+    # via
+    #   jsonschema
+    #   referencing
+scikit-learn==1.5.2
+    # via opendp
+scipy==1.13.1
+    # via
+    #   -r requirements-dev.in
+    #   scikit-learn
+shiny==1.1.0
+    # via
+    #   -r requirements-dev.in
+    #   shinywidgets
+shinywidgets==0.3.3
+    # via -r requirements-dev.in
+six==1.16.0
+    # via
+    #   asttokens
+    #   bleach
+    #   python-dateutil
+sniffio==1.3.1
+    # via anyio
+soupsieve==2.6
+    # via beautifulsoup4
+stack-data==0.6.3
+    # via ipython
+starlette==0.38.5
+    # via shiny
+text-unidecode==1.3
+    # via python-slugify
+threadpoolctl==3.5.0
+    # via scikit-learn
+tinycss2==1.3.0
+    # via nbconvert
+tomli-w==1.0.0
+    # via flit
+tornado==6.4.1
+    # via
+    #   ipykernel
+    #   jupyter-client
+traitlets==5.14.3
+    # via
+    #   comm
+    #   ipykernel
+    #   ipython
+    #   ipywidgets
+    #   jupyter-client
+    #   jupyter-core
+    #   matplotlib-inline
+    #   nbclient
+    #   nbconvert
+    #   nbformat
+typing-extensions==4.12.2
+    # via
+    #   htmltools
+    #   mypy
+    #   pyee
+    #   shiny
+uc-micro-py==1.0.3
+    # via linkify-it-py
+urllib3==2.2.3
+    # via requests
+uvicorn==0.30.6
+    # via shiny
+virtualenv==20.26.5
+    # via pre-commit
+watchfiles==0.24.0
+    # via shiny
+wcwidth==0.2.13
+    # via prompt-toolkit
+webencodings==0.5.1
+    # via
+    #   bleach
+    #   tinycss2
+websockets==13.0.1
+    # via shiny
+wheel==0.44.0
+    # via pip-tools
+widgetsnbextension==4.0.13
+    # via ipywidgets
+
+# The following packages are considered to be unsafe in a requirements file:
+# pip
+# setuptools