diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 94bc1af..ac3705a 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -45,33 +45,3 @@ jobs:
           name: MacTree
           path: MacTree.zip
           if-no-files-found: error
-
-  release:
-    name: release
-    needs: build
-    if: startsWith(github.ref, 'refs/tags/v')
-    runs-on: ubuntu-latest
-    permissions:
-      contents: write
-    steps:
-      - uses: actions/download-artifact@v8
-        with:
-          name: MacTree
-
-      - name: Publish GitHub release
-        env:
-          GH_TOKEN: ${{ github.token }}
-        run: |
-          mv MacTree.zip "MacTree-${GITHUB_REF_NAME}.zip"
-          cat > notes.md <<'NOTES'
-          WizTree-style disk space analyzer for macOS 15 or later (Apple silicon and Intel).
-
-          **Install:** unzip, move `MacTree.app` to Applications, and open it. The build is ad-hoc signed and not notarized, so macOS blocks the first launch. To allow it, go to System Settings › Privacy & Security and click **Open Anyway**. Or run `xattr -dr com.apple.quarantine /Applications/MacTree.app`.
-
-          For complete results, allow **Full Disk Access** when MacTree asks.
-          NOTES
-          gh release create "$GITHUB_REF_NAME" "MacTree-${GITHUB_REF_NAME}.zip" \
-            --repo "$GITHUB_REPOSITORY" \
-            --title "MacTree ${GITHUB_REF_NAME}" \
-            --notes-file notes.md \
-            --generate-notes
diff --git a/scripts/build-app.sh b/scripts/build-app.sh
index a80be4a..0d893ad 100755
--- a/scripts/build-app.sh
+++ b/scripts/build-app.sh
@@ -4,7 +4,9 @@
 # Signing: uses the first "Apple Development" identity in the keychain so that
 # macOS keeps the Full Disk Access grant across rebuilds (an ad-hoc signature
 # changes every build and the grant stops applying). Override with
-# SIGN_IDENTITY="<name or SHA-1>", or SIGN_IDENTITY=- for ad-hoc.
+# SIGN_IDENTITY="<name or SHA-1>", or SIGN_IDENTITY=- for ad-hoc. A
+# "Developer ID Application" identity (or HARDENED_RUNTIME=1) also enables the
+# hardened runtime and a secure timestamp, which notarization requires.
 #
 # UNIVERSAL=1 builds one binary for both Apple silicon and Intel Macs.
 set -euo pipefail
@@ -45,7 +47,11 @@ if [ -z "$IDENTITY" ]; then
     IDENTITY=$(security find-identity -v -p codesigning 2>/dev/null | awk '/"Apple Development/ { print $2; exit }')
 fi
 IDENTITY="${IDENTITY:--}"
-codesign --force --sign "$IDENTITY" "$APP"
+SIGN_FLAGS=(--force --sign "$IDENTITY")
+if [[ "$IDENTITY" == *"Developer ID"* || -n "${HARDENED_RUNTIME:-}" ]]; then
+    SIGN_FLAGS+=(--options runtime --timestamp)
+fi
+codesign "${SIGN_FLAGS[@]}" "$APP"
 if [ "$IDENTITY" = "-" ]; then
     echo "Built $APP (ad-hoc signed)"
 else
diff --git a/scripts/release.sh b/scripts/release.sh
new file mode 100755
index 0000000..0ae9e34
--- /dev/null
+++ b/scripts/release.sh
@@ -0,0 +1,72 @@
+#!/bin/bash
+# Publishes a signed and notarized MacTree release from this Mac.
+#
+#   scripts/release.sh v1.2.3
+#
+# Tags main's HEAD (if the tag does not exist yet) and pushes the tag. Then it
+# builds a universal app and signs it with the Developer ID Application
+# identity (hardened runtime + secure timestamp). The app is notarized with
+# notarytool and the ticket stapled. Finally it creates the GitHub release with
+# MacTree-<tag>.zip (or replaces the zip if the release exists) and prints the
+# SHA-256 for the Homebrew cask.
+#
+# One-time setup (stores an app-specific password in the keychain):
+#   xcrun notarytool store-credentials macTree --apple-id <Apple ID> --team-id <Team ID>
+# NOTARY_PROFILE selects another profile, SIGN_IDENTITY another identity.
+set -euo pipefail
+cd "$(dirname "$0")/.."
+
+TAG="${1:?usage: scripts/release.sh vX.Y.Z}"
+[[ "$TAG" =~ ^v[0-9]+\.[0-9]+\.[0-9]+$ ]] || { echo "Tag must look like v1.2.3." >&2; exit 1; }
+VERSION="${TAG#v}"
+PROFILE="${NOTARY_PROFILE:-macTree}"
+IDENTITY="${SIGN_IDENTITY:-$(security find-identity -v -p codesigning | awk -F'"' '/Developer ID Application/ { print $2; exit }')}"
+[ -n "$IDENTITY" ] || { echo "No Developer ID Application identity in the keychain." >&2; exit 1; }
+if ! xcrun notarytool history --keychain-profile "$PROFILE" > /dev/null 2>&1; then
+    echo "Notary profile '$PROFILE' is missing. Create it once with:" >&2
+    echo "  xcrun notarytool store-credentials $PROFILE --apple-id <Apple ID> --team-id <Team ID>" >&2
+    exit 1
+fi
+
+[ -z "$(git status --porcelain)" ] || { echo "Commit or stash your changes first." >&2; exit 1; }
+git fetch -q origin
+[ "$(git rev-parse HEAD)" = "$(git rev-parse origin/main)" ] || { echo "Check out an up-to-date main first." >&2; exit 1; }
+if git rev-parse -q --verify "refs/tags/$TAG" > /dev/null; then
+    [ "$(git rev-parse "$TAG^{commit}")" = "$(git rev-parse HEAD)" ] || { echo "$TAG exists but is not HEAD." >&2; exit 1; }
+else
+    git tag -a "$TAG" -m "MacTree $VERSION"
+fi
+git push -q origin "$TAG"
+
+UNIVERSAL=1 VERSION="$VERSION" BUILD_NUMBER="$(git rev-list --count HEAD)" SIGN_IDENTITY="$IDENTITY" \
+    ./scripts/build-app.sh
+
+APP=build/MacTree.app
+ZIP="build/MacTree-$TAG.zip"
+rm -f "$ZIP"
+ditto -c -k --keepParent "$APP" "$ZIP"
+xcrun notarytool submit "$ZIP" --keychain-profile "$PROFILE" --wait --output-format json > build/notary.json
+if [ "$(plutil -extract status raw build/notary.json)" != "Accepted" ]; then
+    xcrun notarytool log "$(plutil -extract id raw build/notary.json)" --keychain-profile "$PROFILE" >&2
+    exit 1
+fi
+xcrun stapler staple "$APP"
+spctl -a -vv -t exec "$APP"
+rm -f "$ZIP"
+ditto -c -k --keepParent "$APP" "$ZIP"
+
+NOTES=$(mktemp)
+cat > "$NOTES" <<'NOTES'
+WizTree-style disk space analyzer for macOS 15 or later (Apple silicon and Intel), signed with Developer ID and notarized by Apple.
+
+**Install:** `brew install --cask aodjo/tap/mactree`, or unzip and move `MacTree.app` to Applications.
+
+For complete results, allow **Full Disk Access** when MacTree asks.
+NOTES
+if gh release view "$TAG" > /dev/null 2>&1; then
+    gh release upload "$TAG" "$ZIP" --clobber
+else
+    gh release create "$TAG" "$ZIP" --title "MacTree $TAG" --notes-file "$NOTES" --generate-notes
+fi
+rm -f "$NOTES"
+echo "SHA-256 for the cask: $(shasum -a 256 "$ZIP" | cut -d' ' -f1)"