diff --git a/pkgs/applications/editors/vscode/extensions/update_installed_exts.sh b/pkgs/applications/editors/vscode/extensions/get_updates_installed_exts.sh
old mode 100755
new mode 100644
similarity index 76%
rename from pkgs/applications/editors/vscode/extensions/update_installed_exts.sh
rename to pkgs/applications/editors/vscode/extensions/get_updates_installed_exts.sh
index dd2e8ef247895..82a7eaa30b956
--- a/pkgs/applications/editors/vscode/extensions/update_installed_exts.sh
+++ b/pkgs/applications/editors/vscode/extensions/get_updates_installed_exts.sh
@@ -3,6 +3,9 @@
 # shellcheck shell=bash
 set -eu -o pipefail
 
+# pass <vscode exec or -> <format> to specify format as either json or nix (default nix)
+# note that json format is NOT a json array, but a sequence of json objects
+
 # can be added to your configuration with the following command and snippet:
 # $ ./pkgs/applications/editors/vscode/extensions/update_installed_exts.sh > extensions.nix
 #
@@ -40,7 +43,15 @@ function get_vsixpkg() {
     URL="https://$1.gallery.vsassets.io/_apis/public/gallery/publisher/$1/extension/$2/latest/assetbyname/Microsoft.VisualStudio.Services.VSIXPackage"
 
     # Quietly but delicately curl down the file, blowing up at the first sign of trouble.
-    curl --silent --show-error --retry 3 --fail -X GET -o "$EXTTMP/$N.zip" "$URL"
+    curl --silent --show-error --retry 3 --fail -X GET -o "$EXTTMP/$N.zip" "$URL" || {
+        if (($? > 128))
+        then exit $?
+        fi
+        cat >&2 <<EOF
+unable to download $N
+EOF
+        return
+}
     # Unpack the file we need to stdout then pull out the version
     VER=$(jq -r '.version' <(unzip -qc "$EXTTMP/$N.zip" "extension/package.json"))
     # Calculate the hash
@@ -50,7 +61,9 @@ function get_vsixpkg() {
     rm -Rf "$EXTTMP"
     # I don't like 'rm -Rf' lurking in my scripts but this seems appropriate.
 
-    cat <<-EOF
+    case $FORMAT in
+        nix)
+            cat <<-EOF
   {
     name = "$2";
     publisher = "$1";
@@ -58,25 +71,39 @@ function get_vsixpkg() {
     hash = "$HASH";
   }
 EOF
+            ;;
+        json)
+            printf '{"name": "%s", "publisher": "%s", "version": "%s", "hash": "%s"}\n' "$2" "$1" "$VER" "$HASH"
+            ;;
+    esac
 }
 
 # See if we can find our `code` binary somewhere.
-if [ $# -ne 0 ]; then
+if [ $# -ne 0 ] && [ $1 != "-" ]; then
     CODE=$1
 else
     CODE=$(command -v code || command -v codium)
 fi
 
+if [ $# -ge 2 ]; then
+    FORMAT=$2
+else
+    FORMAT=nix
+fi
+
 if [ -z "$CODE" ]; then
     # Not much point continuing.
     fail "VSCode executable not found"
 fi
 
 # Try to be a good citizen and clean up after ourselves if we're killed.
-trap clean_up SIGINT
+trap clean_up EXIT
 
 # Begin the printing of the nix expression that will house the list of extensions.
-printf '{ extensions = [\n'
+if [ "$FORMAT" = nix ]
+then
+    printf '{ extensions = [\n'
+fi
 
 # Note that we are only looking to update extensions that are already installed.
 for i in $($CODE --list-extensions)
@@ -87,4 +114,7 @@ do
     get_vsixpkg "$OWNER" "$EXT"
 done
 # Close off the nix expression.
-printf '];\n}'
+if [ "$FORMAT" = nix ]
+then
+    printf '];\n}'
+fi
diff --git a/pkgs/applications/editors/vscode/extensions/write_updates_installed_exts.py b/pkgs/applications/editors/vscode/extensions/write_updates_installed_exts.py
new file mode 100644
index 0000000000000..d9eee2805f247
--- /dev/null
+++ b/pkgs/applications/editors/vscode/extensions/write_updates_installed_exts.py
@@ -0,0 +1,36 @@
+# I am not putting a nix-shell shebang here because I can't be bothered to figure out how to put a Python package into it
+
+from json import loads
+from sys import stderr
+from regex import MULTILINE, subn
+import fileinput
+
+if __name__ == "__main__":
+    with open("./default.nix", "r") as file:
+        contents = file.read()
+
+    for line in fileinput.input(encoding="utf-8"):
+        match loads(line):
+            case {"name": name, "publisher": publisher, "version": version, "hash": hash}:
+                pass  # only for assignment
+            case _:
+                raise RuntimeError
+
+        pattern = fr"""(?<="?{publisher}"?\."?{name}"?\s*=\s*buildVscodeMarketplaceExtension\s*{{\s*mktplcRef\s*=\s*){{[^{{}}]*}}(?=;)"""
+
+        replacement = f"""{{
+          publisher = "{publisher}";
+          name = "{name}";
+          version = "{version}";
+          hash = "{hash}";
+        }}"""  # indentation here is somewhat important!
+
+        contents, subcount = subn(pattern, replacement, contents, MULTILINE)
+
+        assert subcount <= 1
+        if subcount == 0:
+            print(f"failed to find match for {line}", file=stderr)
+
+    with open("./default.nix", "w") as file:
+        file.write(contents)
+