diff --git a/.github/workflows/cmake_release.yml b/.github/workflows/cmake_release.yml
index 063e1b63..78f11fdd 100644
--- a/.github/workflows/cmake_release.yml
+++ b/.github/workflows/cmake_release.yml
@@ -264,4 +264,9 @@ jobs:
             installers/*/*.dmg
 
       - name: Create Release
-        run: gh release create ${{ github.ref_name }} --prerelease installers/*/*.msi installers/*/*.zip installers/*/*.dmg
\ No newline at end of file
+        # a product that doesn't build on every platform has no installers of some kinds (Dialogue: no Linux zips)
+        run: |
+          shopt -s nullglob
+          tag="${{ github.ref_name }}"
+          python3 scripts/release_notes.py "${tag%-v*}" "${tag##*-v}" > notes.md
+          gh release create "$tag" --prerelease --notes-file notes.md installers/*/*.msi installers/*/*.zip installers/*/*.dmg
\ No newline at end of file
diff --git a/cmake/AltvanePlugin.cmake b/cmake/AltvanePlugin.cmake
index 4056b3b0..dce2271e 100644
--- a/cmake/AltvanePlugin.cmake
+++ b/cmake/AltvanePlugin.cmake
@@ -46,6 +46,15 @@ function(altvane_add_plugin target)
     if (NOT ARG_AAX_CATEGORY)
         set(ARG_AAX_CATEGORY AAX_ePlugInCategory_None)
     endif ()
+    # checked here, on every platform, rather than only where LV2 is built (patch_lv2.py fails the build there)
+    file(STRINGS "${CMAKE_SOURCE_DIR}/packaging/patch_lv2.py" lv2_lines REGEX "^    '[a-z]+': 'lv2:")
+    list(TRANSFORM lv2_lines REPLACE "^    '([a-z]+)'.*" "\\1" OUTPUT_VARIABLE lv2_known)
+    foreach (tag IN LISTS ARG_LV2_TAGS)
+        string(TOLOWER "${tag}" tag_lower)
+        if (NOT tag_lower IN_LIST lv2_known)
+            message(FATAL_ERROR "altvane_add_plugin(${target}): '${tag}' is not an LV2 tag packaging/patch_lv2.py knows")
+        endif ()
+    endforeach ()
 
     set(product_dir "${CMAKE_CURRENT_SOURCE_DIR}")
 
diff --git a/scripts/release_notes.py b/scripts/release_notes.py
new file mode 100755
index 00000000..d6dcc3c3
--- /dev/null
+++ b/scripts/release_notes.py
@@ -0,0 +1,43 @@
+#!/usr/bin/env python3
+"""Print the release notes for one product's release: its CHANGELOG section and how to install an unsigned build.
+
+    scripts/release_notes.py <product> <version>
+
+The section is the one headed `## <version>` in products/<product>/CHANGELOG.md. Its headings move up a level and its
+hard-wrapped lines are joined, since GitHub keeps line breaks in release notes."""
+import pathlib
+import re
+import sys
+
+root = pathlib.Path(__file__).resolve().parent.parent
+product, version = sys.argv[1], sys.argv[2]
+changelog = (root / "products" / product / "CHANGELOG.md").read_text()
+match = re.search(rf"^## {re.escape(version)}\n(.*?)(?=^## |\Z)", changelog, re.S | re.M)
+if not match:
+    sys.exit(f"products/{product}/CHANGELOG.md has no '## {version}' section")
+notes = match.group(1).strip()
+notes = re.sub(r"^### ", "## ", notes, flags=re.M)
+notes = re.sub(r"\n {2,}(?=\S)", " ", notes)  # a list item's continuation lines
+notes = re.sub(r"(?<=[^\n])\n(?=[^\n\-#*\s|])", " ", notes)  # a paragraph's
+
+platforms_file = root / "products" / product / "PLATFORMS"
+platforms = None
+if platforms_file.exists():
+    platforms = {line.strip() for line in platforms_file.read_text().splitlines()
+                 if line.strip() and not line.startswith("#")}
+
+
+def builds_on(system: str) -> bool:
+    return platforms is None or any(p.startswith(system) for p in platforms)
+
+
+install = ["## Installing", "", "These builds are not signed yet.", ""]
+if builds_on("Darwin"):
+    install.append("- **macOS:** if macOS says the installer can't be opened, open System Settings → Privacy & Security "
+                   "and choose **Open Anyway**.")
+if builds_on("Windows"):
+    install.append("- **Windows:** if SmartScreen stops the installer, choose **More info → Run anyway**.")
+if builds_on("Linux"):
+    install.append("- **Linux:** unzip and copy the plug-ins into `~/.vst3` or `~/.lv2`.")
+install += ["", "Pick the AVX2 build on x86-64 machines from about 2013 onwards; the plain x86-64 build runs everywhere."]
+print(notes + "\n\n" + "\n".join(install))