diff --git a/.github/workflows/check.yaml b/.github/workflows/check.yaml
index df25fc0..9736e7f 100644
--- a/.github/workflows/check.yaml
+++ b/.github/workflows/check.yaml
@@ -133,7 +133,7 @@ jobs:
             apt update
             apt install -t unstable -y python3-flake8
           fi
-      - name: Workaround for https://github.com/actions/checkout/pull/762 not persisting
+      - name: Workaround for https://github.com/actions/checkout/issues/1169
         run: git config --global --add safe.directory "$PWD"
       - name: Install remaining dependencies
         run: make venv-system-site-packages
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
new file mode 100644
index 0000000..2429480
--- /dev/null
+++ b/CONTRIBUTING.md
@@ -0,0 +1,67 @@
+# Contributing to strava-offline
+
+## Development
+
+Obtain the source code:
+
+    $ git clone https://github.com/liskin/strava-offline
+
+Setup Python virtual env and install missing dependencies:
+
+    $ make
+
+Make changes using your preferred editor.
+
+Then invoke lints, tests, …:
+
+    $ make check
+
+These checks are also invoked in [CI (GitHub Actions)][ci] (against multiple
+Python versions and also using different Linux distributions Python packages)
+whenever a branch is pushed or a pull request is opened. You may need to
+enable Actions in your fork's settings.
+
+Other common tasks are available in the [Makefile](Makefile):
+
+<!-- include tests/readme/make-help.md -->
+<!--
+    $ cd "$TESTDIR"/../..
+
+    $ function make {
+    >   command make --no-print-directory COLUMNS=120 "$@" 2>/dev/null
+    > }
+-->
+
+    $ make help
+    venv-system-site-packages: Setup ./.venv/ (--system-site-packages)
+    venv: Setup ./.venv/
+    pipx: Install locally using pipx
+    pipx-site-packages: Install locally using pipx (--system-site-packages)
+    check: Invoke all checks (lints, tests, readme)
+    lint: Invoke lints
+    lint-flake8:
+    lint-mypy:
+    lint-isort:
+    test: Invoke tests
+    test-pytest:
+    test-prysk:
+    readme: Update usage/examples in *.md and fail if it differs from version control
+    dist: Build distribution artifacts (tar, wheel)
+    twine-upload: Release to PyPI
+    ipython: Invoke IPython in venv (not installed by default)
+    clean: Clean all gitignored files/directories
+    template-update: Re-render cookiecutter template into the template branch
+    template-merge: Re-render cookiecutter template and merge into the current branch
+    check-wheel: Check that the wheel we build works in a completely empty venv (i.e. check for unspecified dependencies)
+    help: Display this help
+<!-- end include tests/readme/make-help.md -->
+
+[ci]: https://github.com/liskin/strava-offline/actions
+
+## Style Guidelines
+
+* Try to follow the existing style (where it's not already enforced by a
+  linter). This applies to both code and git commits.
+
+* Familiarise yourself with [the seven rules of a great Git commit
+  message](https://cbea.ms/git-commit/#seven-rules).
diff --git a/Makefile b/Makefile
index d86c28c..bb42342 100644
--- a/Makefile
+++ b/Makefile
@@ -13,55 +13,63 @@ VENV_WHEEL_PYTHON = $(VENV_WHEEL)/bin/python
 PACKAGE := $(shell sed -ne '/^name / { y/-/_/; s/^.*=\s*"\(.*\)"/\1/p }' pyproject.toml)
 
 TEMPLATES_DIR = $(HOME)/src
-TEMPLATE := $(shell realpath --relative-to=. $(TEMPLATES_DIR)/cookiecutter-python-cli)
+TEMPLATE = $(eval TEMPLATE := $$(shell realpath --relative-to=. $$(TEMPLATES_DIR)/cookiecutter-python-cli))$(TEMPLATE)
 
 .PHONY: venv-system-site-packages
+## Setup ./.venv/ (--system-site-packages)
 venv-system-site-packages:
 	$(MAKE) VENV_USE_SYSTEM_SITE_PACKAGES=1 venv
 
 .PHONY: venv
+## Setup ./.venv/
 venv: $(VENV_DONE)
 
 .PHONY: pipx
+## Install locally using pipx
 pipx:
 	pipx install --editable .
 
 .PHONY: pipx-site-packages
+## Install locally using pipx (--system-site-packages)
 pipx-site-packages:
 	pipx install --system-site-packages --editable .
 
 .PHONY: check
+## Invoke all checks (lints, tests, readme)
 check: lint test readme
 
 .PHONY: lint
+## Invoke lints
 lint: lint-flake8 lint-mypy lint-isort
 
 LINT_SOURCES = src/ tests/
 
 .PHONY: lint-flake8
+##
 lint-flake8: $(VENV_DONE)
 	$(VENV_PYTHON) -m flake8 $(LINT_SOURCES)
 
 .PHONY: lint-mypy
+##
 lint-mypy: $(VENV_DONE)
 	$(VENV_PYTHON) -m mypy --show-column-numbers $(LINT_SOURCES)
 
 .PHONY: lint-isort
+##
 lint-isort: $(VENV_DONE)
 	$(VENV_PYTHON) -m isort --check $(LINT_SOURCES)
 
 .PHONY: test
+## Invoke tests
 test: test-pytest test-prysk
 
 .PHONY: test-pytest
+##
 test-pytest: $(VENV_DONE)
 	$(VENV_PYTHON) -m pytest $(PYTEST_FLAGS) tests/
 
-.PHONY: readme
-readme: README.md
-	git diff --exit-code $^
-
 .PHONY: test-prysk
+##
 test-prysk: PRYSK_INTERACTIVE=$(shell [ -t 0 ] && echo --interactive)
 test-prysk: $(VENV_DONE)
 	PATH="$(CURDIR)/$(VENV)/bin:$$PATH" \
@@ -70,37 +78,49 @@ test-prysk: $(VENV_DONE)
 	$(VENV_PYTHON) -m prysk --indent=4 --shell=/bin/bash $(PRYSK_INTERACTIVE) \
 		$(wildcard tests/*.md tests/*/*.md tests/*/*/*.md)
 
-.PHONY: README.md
-README.md: test-prysk
-	tests/include.py < $@ > $@.tmp
-	mv -f $@.tmp $@
+.PHONY: readme
+## Update usage/examples in *.md and fail if it differs from version control
+readme: $(wildcard *.md)
+	git diff --exit-code $^
+
+.PHONY: $(wildcard *.md)
+$(wildcard *.md): $(VENV_DONE) test-prysk
+	$(VENV_PYTHON) tests/include-preproc.py --comment-start="<!-- " --comment-end=" -->" $@
 
 .PHONY: dist
+## Build distribution artifacts (tar, wheel)
 dist: $(VENV_DONE)
 	rm -rf dist/
 	$(VENV_PYTHON) -m build --outdir dist
 
 .PHONY: twine-upload
+## Release to PyPI
 twine-upload: dist
 	$(VENV_PYTHON) -m twine upload $(wildcard dist/*)
 
 .PHONY: ipython
+## Invoke IPython in venv (not installed by default)
 ipython: $(VENV_DONE)
 	$(VENV_PYTHON) -m IPython
 
 .PHONY: clean
+## Clean all gitignored files/directories
 clean:
 	git clean -ffdX
 
 .PHONY: template-update
+## Re-render cookiecutter template into the template branch
 template-update:
 	$(TEMPLATE)/update.sh -t $(TEMPLATE) -p . -b template -i .cookiecutter.json
 
 .PHONY: template-merge
+## Re-render cookiecutter template and merge into the current branch
 template-merge: template-update
 	git merge template
 
 .PHONY: check-wheel
+## Check that the wheel we build works in a completely empty venv
+## (i.e. check for unspecified dependencies)
 check-wheel: dist
 	$(PYTHON) -m venv --clear --without-pip $(VENV_WHEEL)
 	cd $(VENV_WHEEL) && $(PYTHON) -m pip --isolated download pip
@@ -121,7 +141,7 @@ endef
 # workaround for https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1003252 and/or https://github.com/pypa/pip/issues/6264
 ifneq ($(VENV_USE_SYSTEM_SITE_PACKAGES),)
 ifneq ($(shell test -f /etc/debian_version && python3 -c 'import sys; exit(not(sys.version_info < (3, 10)))' && echo x),)
-$(info XXX: using SETUPTOOLS_USE_DISTUTILS=stdlib workaround)
+$(warning XXX: using SETUPTOOLS_USE_DISTUTILS=stdlib workaround)
 $(VENV_DONE): export SETUPTOOLS_USE_DISTUTILS := stdlib
 endif
 endif
@@ -130,3 +150,5 @@ $(VENV_DONE): $(MAKEFILE_LIST) pyproject.toml
 	$(if $(VENV_USE_SYSTEM_SITE_PACKAGES),$(VENV_CREATE_SYSTEM_SITE_PACKAGES),$(VENV_CREATE))
 	$(VENV_PYTHON) -m pip install -e $(VENV_PIP_INSTALL)
 	touch $@
+
+include _help.mk
diff --git a/README.md b/README.md
index 42506e1..8162f40 100644
--- a/README.md
+++ b/README.md
@@ -46,7 +46,7 @@ pip install strava-offline
                        /home/user/.config/strava_offline/config.yaml]
       --config-sample  Show sample configuration file
       --help           Show this message and exit.
-<!-- end include -->
+<!-- end include tests/readme/help.md -->
 
 <!-- FIXME: example -->
 
@@ -60,9 +60,28 @@ Sample config file can be generated using the `--config-sample` flag:
 
 <!-- include tests/readme/config-sample.md -->
     $ strava-offline --config-sample
-<!-- end include -->
+<!-- end include tests/readme/config-sample.md -->
 
-## Donations (♥ = €)
+## Contributing
+
+### Code
+
+We welcome bug fixes, (reasonable) new features, documentation improvements,
+and more. Submit these as GitHub pull requests. Use GitHub issues to report
+bugs and discuss non-trivial code improvements; alternatively, get in touch
+via [IRC/Matrix/Fediverse](https://work.lisk.in/contact/).
+
+See [CONTRIBUTING.md](CONTRIBUTING.md) for more details about the code base
+(including running tests locally).
+
+Note that this project was born out of a desire to solve a problem I was
+facing. While I'm excited to share it with the world, keep in mind that I'll
+be prioritizing features and bug fixes that align with my personal use cases.
+There may be times when I'm busy with other commitments and replies to
+contributions might be delayed, or even occasionally missed. Progress may come
+in bursts. Adjust your expectations accordingly.
+
+### Donations (♥ = €)
 
 If you like this tool and wish to support its development and maintenance,
 please consider [a small donation](https://www.paypal.me/lisknisi/10EUR) or
diff --git a/_help.mk b/_help.mk
new file mode 100644
index 0000000..fabb20a
--- /dev/null
+++ b/_help.mk
@@ -0,0 +1,15 @@
+# orig src: https://github.com/liskin/dotfiles/blob/home/_help.mk
+
+.PHONY: help
+## Display this help
+help: COLUMNS=$(shell tput cols)
+help:
+	@$(MAKE) --silent help-src \
+		| perl -Mfeature=say -MText::Wrap -0777 -ne 'while(/((?:^##(?:| .*)$$(?#)\n)+)(^.*:)/gm) { my ($$t, $$h) = ($$2, $$1); $$h =~ s/^## ?//gm; $$h =~ s/\s+/ /g; $$h =~ s/^\s+|\s+$$//g; say "$$t $$h"; }' | fmt $(if $(COLUMNS),-$(COLUMNS)) -t
+
+.PHONY: help-src
+help-src: help-src-makefiles
+
+.PHONY: help-src-makefiles
+help-src-makefiles:
+	@cat $(MAKEFILE_LIST)
diff --git a/tests/include-preproc.py b/tests/include-preproc.py
new file mode 100755
index 0000000..4e5b290
--- /dev/null
+++ b/tests/include-preproc.py
@@ -0,0 +1,54 @@
+#!/usr/bin/env python3
+
+# orig src: https://github.com/liskin/dotfiles/blob/home/bin/liskin-include-preproc.py
+
+from __future__ import annotations  # python 3.8 compat
+
+from dataclasses import dataclass
+from pathlib import Path
+import re
+
+import click
+
+
+@dataclass
+class Subst:
+    comment_start: str
+    comment_end: str
+
+    def include(self, m: re.Match[str]) -> str:
+        filename = m[1]
+
+        content = self.includes(Path(filename).expanduser().read_text())
+        nl = "\n" if not content.endswith("\n") else ""
+
+        cs = self.comment_start
+        ce = self.comment_end
+        return f"{cs}include {filename}{ce}\n{content}{nl}{cs}end include {filename}{ce}"
+
+    def includes(self, s: str) -> str:
+        cs = re.escape(self.comment_start)
+        ce = re.escape(self.comment_end)
+        regex = f"^{cs}include (\\S+){ce}$.*?^{cs}end include \\1{ce}$"
+        return re.sub(regex, self.include, s, flags=re.DOTALL | re.MULTILINE)
+
+
+@click.command(context_settings={"show_default": True})
+@click.option("--comment-start", type=str, default="## ")
+@click.option("--comment-end", type=str, default="")
+@click.argument("filename", type=click.Path(exists=True, allow_dash=True))
+def main(comment_start, comment_end, filename):
+    """
+    Simple preprocessor for including files in one another.
+    Substitution is done in-place: the input file is modified and directives are retained so it can
+    serve as an input again.
+    """
+    with click.open_file(filename, "r") as f:
+        input = f.read()
+    output = Subst(comment_start=comment_start, comment_end=comment_end).includes(input)
+    with click.open_file(filename, "w", atomic=True) as f:
+        f.write(output)
+
+
+if __name__ == "__main__":
+    main()
diff --git a/tests/include.py b/tests/include.py
deleted file mode 100755
index acd0bd6..0000000
--- a/tests/include.py
+++ /dev/null
@@ -1,21 +0,0 @@
-#!/usr/bin/env python3
-
-from __future__ import annotations
-
-from pathlib import Path
-import re
-from sys import stdin
-from sys import stdout
-
-
-def include(m: re.Match[str]) -> str:
-    f = Path(m[1]).read_text()
-    return f"<!-- include {m[1]} -->\n{f}<!-- end include -->"
-
-
-def includes(s: str) -> str:
-    return re.sub(r"(?s)<!-- include (\S+) .*? end include -->", include, s)
-
-
-if __name__ == "__main__":
-    stdout.write(includes(stdin.read()))
diff --git a/tests/readme/make-help.md b/tests/readme/make-help.md
new file mode 100644
index 0000000..1589d56
--- /dev/null
+++ b/tests/readme/make-help.md
@@ -0,0 +1,30 @@
+<!--
+    $ cd "$TESTDIR"/../..
+
+    $ function make {
+    >   command make --no-print-directory COLUMNS=120 "$@" 2>/dev/null
+    > }
+-->
+
+    $ make help
+    venv-system-site-packages: Setup ./.venv/ (--system-site-packages)
+    venv: Setup ./.venv/
+    pipx: Install locally using pipx
+    pipx-site-packages: Install locally using pipx (--system-site-packages)
+    check: Invoke all checks (lints, tests, readme)
+    lint: Invoke lints
+    lint-flake8:
+    lint-mypy:
+    lint-isort:
+    test: Invoke tests
+    test-pytest:
+    test-prysk:
+    readme: Update usage/examples in *.md and fail if it differs from version control
+    dist: Build distribution artifacts (tar, wheel)
+    twine-upload: Release to PyPI
+    ipython: Invoke IPython in venv (not installed by default)
+    clean: Clean all gitignored files/directories
+    template-update: Re-render cookiecutter template into the template branch
+    template-merge: Re-render cookiecutter template and merge into the current branch
+    check-wheel: Check that the wheel we build works in a completely empty venv (i.e. check for unspecified dependencies)
+    help: Display this help