diff --git a/release.sh b/release.sh
index 6447044..4d36d1a 100755
--- a/release.sh
+++ b/release.sh
@@ -1,10 +1,256 @@
 #!/usr/bin/env bash
 # -----------------------------------------------------------------------------
-# bat-extras | Copyright (C) 2019-2020 eth-p | MIT License
+# bat-extras | Copyright (C) 2019-2023 eth-p | MIT License
 #
 # Repository: https://github.com/eth-p/bat-extras
 # Issues:     https://github.com/eth-p/bat-extras/issues
 # -----------------------------------------------------------------------------
+source "$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)/build.sh"
+
+# -----------------------------------------------------------------------------
+# Release-as-a-Library Functions:
+# -----------------------------------------------------------------------------
+
+# Prints the path to the git workspace.
+if ! batextras:is_function_defined ::get_git_workspace; then
+	batextras:get_git_workspace() {
+		batextras:lazy_done "${FUNCNAME[0]}" \
+			"$(batextras:get_project_directory)"
+	}
+fi
+
+# Prints the commit of the latest-tagged version of bat-extras.
+if ! batextras:is_function_defined ::get_current_commit; then
+	batextras:get_current_commit() {
+		batextras:lazy_done "${FUNCNAME[0]}" \
+			"$(batextras:git rev-parse HEAD)"
+	}
+fi
+
+# Prints the commit of the latest-tagged version of bat-extras.
+if ! batextras:is_function_defined ::get_previous_tag_commit; then
+	batextras:get_previous_tag_commit() {
+		local latest_tag
+		local before_latest_tag
+		{
+			read -r latest_tag
+			read -r before_latest_tag
+		} < <(batextras:git rev-list --tags --max-count=2)
+
+		# If the latest commit is a tag, go to the one before that.
+		if [[ "$(batextras:get_current_commit)" = "$latest_tag" ]]; then
+			latest_tag="${before_latest_tag}"
+		fi
+
+		batextras:lazy_done "${FUNCNAME[0]}" "$latest_tag"
+	}
+fi
+
+# Prints the ref name of the latest-tagged version of bat-extras.
+if ! batextras:is_function_defined ::get_previous_tag_name; then
+	batextras:get_previous_tag_name() {
+		batextras:lazy_done "${FUNCNAME[0]}" \
+			"$(batextras:git describe --tags --abbrev=0 "$(batextras:get_previous_tag_commit)")"
+	}
+fi
+
+# Returns the suffix for a day of the month.
+#
+# Arguments:
+#     1  -- The day number.
+#
+# Output:
+#     The suffix.
+batextras:day_suffix() {
+	case "$1" in
+		11 | 12 | 13) echo "th" ;;
+		*1) echo "st" ;;
+		*2) echo "nd" ;;
+		*3) echo "rd" ;;
+		*)  echo "th" ;;
+	esac
+}
+
+# Runs `git` within the project directory.
+#
+# This takes the same arguments as git (with the exception of `-C`), and
+# does exactly what `git` would normally do.
+batextras:git() {
+	git -C "$(batextras:get_git_workspace)" "$@"
+	return $?
+}
+
+# Creates the zipball for release.
+# YOU MUST BUILD THE PROJECT FIRST!
+#
+# Arguments:
+#     1  -- The absolute path to the output zip file.
+#
+# Stderr:
+#     Messages.
+batextras:create_package() {
+	local artifact="$1"
+	local bin_dir man_dir doc_dir
+	bin_dir="$(batextras:get_output_bin_directory)"
+	man_dir="$(batextras:get_output_man_directory)"
+	doc_dir="$(batextras:get_docs_directory)"
+
+	(
+		# Remove the old zipball, if one exists.
+		if [[ -f "$artifact" ]]; then
+			rm "$artifact" || return $?
+		fi
+
+		# Add the bin directory.
+		cd "$(dirname -- "$bin_dir")" || return $?
+		zip -r "$artifact" "$(basename -- "$bin_dir")"
+
+		# Add the doc directory.
+		cd "$(dirname -- "$doc_dir")" || return $?
+		zip -ru "$artifact" "$(basename -- "$doc_dir")"
+
+		# Add the man directory.
+		if [[ -d "$man_dir" ]]; then
+			cd "$(dirname -- "$man_dir")" || return $?
+			zip -ru "$artifact" "$(basename -- "$man_dir")"
+		fi
+	) 1>&2
+}
+
+# Generates a Markdown changelog for all changes between two commits.
+#
+# Arguments:
+#     1  -- The first commit, exclusive.
+#     2  -- The second commit, inclusive.
+#     3  -- A filter in regex.
+#
+# Output:
+#     The changelog.
+batextras:generate_changelog() {
+	local start_commit="$1"
+	local end_commit="$2"
+	local filter="${3}"
+
+	# Generate sed replacement patterns.
+	local script_links=()
+	local script_names=()
+	local script script_name
+	while read -r script; do
+		script_name="$(basename "$script" .sh)"
+		script_names+=("$script_name")
+	done < <(batextras:get_source_paths)
+
+	local script_pattern
+	script_pattern="$(printf 's/\\(%s\\)/`\\1`/;' "${script_names[@]}")"
+
+	# Generate the changelog.
+	local changelog=''
+	local commit
+	local affected_module
+	local commit_message
+	while read -r commit; do
+		commit_message="$(batextras:git show -s --format=%s "$commit")"
+
+		if ! [[ "$commit_message" =~ ^([a-z-]+):[[:space:]]*(.*)$ ]]; then
+			continue
+		fi
+
+		affected_module="${BASH_REMATCH[1]}"
+
+		# Make module names consistent.
+		case "$affected_module" in
+			dev | lib | mdroff) affected_module="developer" ;;
+			tests) affected_module="test" ;;
+			doc) affected_module="docs" ;;
+		esac
+
+		# Append to changelog.
+		if [[ "$affected_module" =~ ^($filter)$ ]]; then
+			changelog="$changelog"$'\n'" - ${commit_message}"
+		fi
+	done < <(batextras:git rev-list "${start_commit}..${end_commit}")
+
+	# Print the changelog.
+	changelog="$(sed "$script_pattern" <<< "$changelog")"
+	printf "%s\n" "${changelog:1}"
+	return 0
+}
+
+# Generates the Markdown release notes.
+#
+# Arguments:
+#     1  -- The oldest commit, exclusive.
+#     2  -- The newest commit, inclusive.
+#
+# Output:
+#     The changelog.
+batextras:generate_release_notes() {
+	local commit_oldest="$1"
+	local commit_newest="$2"
+	local commit_newest_url="https://github.com/eth-p/bat-extras/tree/${commit_newest}"
+	local date_str
+
+	# Get the commit date.
+	local date_year date_month date_day date_month_text date_day_suffix
+	read -r date_year date_month date_day date_month_text \
+		< <(batextras:git show -s --format="%cd" --date="format:%Y %m %d %B" "$commit_newest")
+
+	date_day_suffix="$(batextras:day_suffix "$date_day")"
+	date_str="${date_month_text} ${date_day}${date_day_suffix}, ${date_year}"
+
+	# For each built script, we want to:
+	#   - Get the name of the script.
+	#   - Get a link to the documentation.
+	#   - Add it to the filter for non-developer items.
+	local script_name script_names script_links script_filters script_list_markdown
+	script_links=()
+	script_names=()
+	script_filters=''
+
+	while read -r script; do
+		script_name="$(basename "$script" .sh)"
+		script_names+=("$script_name")
+		script_links+=("[\`${script_name}\`](https://github.com/eth-p/bat-extras/blob/${commit_newest}/doc/${script_name}.md)")
+		script_filters="${script_filters}|$(printf "%q" "$script_name")"
+	done < <(batextras:get_source_paths)
+
+	script_filters="${script_filters:1}" # Remove the leading "|"
+	script_list_markdown="$(printf "%s, " "${script_links[@]:0:$((${#script_links[@]} - 1))}")"
+	script_list_markdown="${script_list_markdown}and ${script_links[$((${#script_links[@]} - 1))]}"
+
+	# Get the changelog.
+	local changelog changelog_dev
+	changelog="$(batextras:generate_changelog "$commit_oldest" "$commit_newest" "$script_filters")"
+	changelog_dev="$(batextras:generate_changelog "$commit_oldest" "$commit_newest" "test|developer|ci|build")"
+
+	# Print the template.
+	{ sed '/\\$/{N;s/\\\n//;s/\n//p;}'; } <<- EOF
+		This contains the latest versions of ${script_list_markdown} as of commit [${commit_newest}](${commit_newest_url}) (${date_str}).
+
+		**This is provided as a convenience only.**
+		I would still recommend following the installation instructions in [the README](https://github.com/eth-p/bat-extras#installation-) for the most up-to-date versions.
+
+		### Changes
+		${changelog}
+
+		### Developer
+		<details>
+		<div markdown="1">
+
+		${changelog_dev}
+
+		</div>
+		</details>
+	EOF
+
+}
+
+# -----------------------------------------------------------------------------
+# Main:
+# Only run everything past this point if the script is not sourced.
+# -----------------------------------------------------------------------------
+(return 0 2>/dev/null) && return 0
+
 HERE="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 DATE="$(date +%Y%m%d)"
 VERSION="$(< "${HERE}/version.txt")"
@@ -14,22 +260,23 @@ SRC="$HERE/src"
 source "${LIB}/print.sh"
 source "${LIB}/opt.sh"
 # -----------------------------------------------------------------------------
+set -euo pipefail
 
 # -----------------------------------------------------------------------------
 # Options.
 OPT_ARTIFACT="bat-extras-${DATE}.zip"
 OPT_SINCE=
 OPT_BAD_IDEA=false
-OPT_BIN_DIR="$HERE/bin"
-OPT_DOC_DIR="$HERE/doc"
-OPT_MAN_DIR="$HERE/man"
+OPT_BIN_DIR="$(batextras:get_output_bin_directory)"
+OPT_DOC_DIR="$(batextras:get_docs_directory)"
+OPT_MAN_DIR="$(batextras:get_output_man_directory)"
 
 while shiftopt; do
 	case "$OPT" in
 		--since)
 			shiftval
 			OPT_SINCE="$OPT_VAL"
-			if ! git rev-parse "$OPT_SINCE" &> /dev/null; then
+			if ! batextras:git rev-parse "$OPT_SINCE" &> /dev/null; then
 				printc "%{RED}%s: unknown commit or tag for '%s'\n" "$PROGRAM" "$OPT"
 				exit 1
 			fi
@@ -48,6 +295,10 @@ done
 
 # -----------------------------------------------------------------------------
 # Verify the version matches today's date.
+
+VERSION="$(source "${LIB}/constants.sh" && echo "${PROGRAM_VERSION}")"
+VERSION_EXPECTED="$(date +%Y.%m.%d)"
+
 if [[ "$VERSION" != "$VERSION_EXPECTED" ]] && ! "$OPT_BAD_IDEA"; then
 	printc "%{RED}The expected version does not match %{DEFAULT}version.txt%{RED}!%{CLEAR}\n"
 	printc "%{RED}Expected: %{YELLOW}%s%{CLEAR}\n" "$VERSION_EXPECTED"
@@ -55,6 +306,18 @@ if [[ "$VERSION" != "$VERSION_EXPECTED" ]] && ! "$OPT_BAD_IDEA"; then
 	exit 1
 fi
 
+# -----------------------------------------------------------------------------
+# Verify the working tree is clean-ish.
+
+if ! "$OPT_BAD_IDEA"; then
+	while read -r flags file; do
+		if [[ "$flags" =~ M ]]; then
+			printc "%{RED}Found an uncommitted change in %{DEFAULT}%s%{RED}!%{CLEAR}\n" "$file"
+			exit 1
+		fi
+	done < <(batextras:git status --porcelain)
+fi
+
 # -----------------------------------------------------------------------------
 # Build files.
 
@@ -75,110 +338,13 @@ printc "%{YELLOW}Building scripts...%{CLEAR}\n"
 # Build package.
 
 printc "%{YELLOW}Packaging artifacts...%{CLEAR}\n"
-(
-	rm "$OPT_ARTIFACT"
-	cd "$(dirname "$OPT_BIN_DIR")"
-	zip -r "$OPT_ARTIFACT" "$(basename "$OPT_BIN_DIR")"
-	cd "$(dirname "$OPT_DOC_DIR")"
-	zip -ru "$OPT_ARTIFACT" "$(basename "$OPT_DOC_DIR")"
-	if [[ -d "$OPT_MAN_DIR" ]]; then
-		cd "$(dirname "$OPT_MAN_DIR")"
-		zip -ru "$OPT_ARTIFACT" "$(basename "$OPT_MAN_DIR")"
-	fi
-)
-
+batextras:create_package "$OPT_ARTIFACT"
 printc "%{YELLOW}Package created as %{BLUE}%s%{YELLOW}.%{CLEAR}\n" "$OPT_ARTIFACT"
 
 # -----------------------------------------------------------------------------
 # Print template description package.
 
 printc "%{YELLOW}Release description:%{CLEAR}\n"
-
-# Get the commit hash.
-COMMIT="$(git rev-parse HEAD)"
-COMMIT_URL="https://github.com/eth-p/bat-extras/tree/${COMMIT}"
-
-# Get the release date string.
-DATE_DAY="$(date +%e | sed 's/ //')"
-DATE_SUFFIX=""
-case "$DATE_DAY" in
-	11 | 12 | 13) DATE_SUFFIX="th" ;;
-	*1) DATE_SUFFIX="st" ;;
-	*2) DATE_SUFFIX="nd" ;;
-	*3) DATE_SUFFIX="rd" ;;
-	*)  DATE_SUFFIX="th" ;;
-esac
-DATE_STR="$(date +'%B') ${DATE_DAY}${DATE_SUFFIX}, $(date +'%Y')"
-
-# Get the script names.
-script_links=()
-script_names=()
-for script in "$SRC"/*.sh; do
-	script_name="$(basename "$script" .sh)"
-	script_names+=("$script_name")
-	script_links+=("[\`${script_name}\`](https://github.com/eth-p/bat-extras/blob/${COMMIT}/doc/${script_name}.md)")
-done
-
-script_pattern="$(printf 's/\\(%s\\)/`\\1`/;' "${script_names[@]}")"
-SCRIPTS="$(printf "%s, " "${script_links[@]:0:$((${#script_links[@]} - 1))}")"
-SCRIPTS="${SCRIPTS}and ${script_links[$((${#script_links[@]} - 1))]}"
-
-# Get the changelog.
-CHANGELOG_DEV=''
-CHANGELOG=''
-if [[ -n "$OPT_SINCE" ]]; then
-	ref="$(git rev-parse HEAD)"
-	end="$(git rev-parse "$OPT_SINCE")"
-	while [[ "$ref" != "$end" ]]; do
-		is_developer=false
-		ref_message="$(git show -s --format=%s "$ref")"
-		ref="$(git rev-parse "${ref}~1")"
-
-		if [[ "$ref_message" =~ ^([a-z-]+):[[:space:]]*(.*)$ ]]; then
-			affected_module="${BASH_REMATCH[1]}"
-
-			# Make module names consistent.
-			case "$affected_module" in
-				dev | lib | mdroff) affected_module="developer" ;;
-				tests) affected_module="test" ;;
-				doc) affected_module="docs" ;;
-			esac
-
-			# Switch to the correct changelog.
-			case "$affected_module" in
-				test | developer | ci | build) is_developer=true ;;
-			esac
-		fi
-
-		# Append to changelog.
-		if "$is_developer"; then
-			CHANGELOG_DEV="$CHANGELOG_DEV"$'\n'" - ${ref_message}"
-		else
-			CHANGELOG="$CHANGELOG"$'\n'" - ${ref_message}"
-		fi
-	done
-fi
-
-CHANGELOG="$(sed "$script_pattern" <<< "$CHANGELOG")"
-CHANGELOG_DEV="$(sed "$script_pattern" <<< "$CHANGELOG_DEV")"
-
-# Print the template.
-sed '/\\$/{N;s/\\\n//;s/\n//p;}' <<- EOF
-	This contains the latest versions of $SCRIPTS as of commit [$(git rev-parse --short HEAD)]($COMMIT_URL) (${DATE_STR}).
-	
-	**This is provided as a convenience only.**
-	I would still recommend following the installation instructions in \
-	[the README](https://github.com/eth-p/bat-extras#installation-) for the most up-to-date versions.
-	
-	### Changes
-	$CHANGELOG
-	
-	### Developer
-	<details>
-	<div markdown="1">
-	
-	$CHANGELOG_DEV
-	
-	</div>
-	</details>
-EOF
+batextras:generate_release_notes \
+	"$(batextras:get_previous_tag_name)" \
+	"$(batextras:get_current_commit)"