diff --git a/lib/RevBank/Products.pm b/lib/RevBank/Products.pm
new file mode 100644
index 0000000..2adab62
--- /dev/null
+++ b/lib/RevBank/Products.pm
@@ -0,0 +1,141 @@
+package RevBank::Products;
+
+use v5.32;
+use warnings;
+use experimental 'signatures';  # stable since 5.36
+
+use RevBank::Prompt;
+use RevBank::Global;
+use Exporter qw(import);
+our @EXPORT = qw(read_products);
+
+sub read_products($filename = "revbank.products", $default_contra = "+sales/products") {
+    state %cache;   # $filename => \%products
+    state %mtimes;  # $filename => mtime
+
+    my $mtime = \$mtimes{$filename};
+
+    return $cache{$filename} if $$mtime and $$mtime == -M $filename;
+
+    my %products;
+    my $linenr = 0;
+    my $warnings = 0;
+
+    $$mtime = -M $filename;
+    for my $line (slurp $filename) {
+        $linenr++;
+
+        next if $line =~ m[
+            ^\s*\#    # comment line
+            |
+            ^\s*$     # empty line, or only whitespace
+        ]x;
+
+        my @split = RevBank::Prompt::split_input($line);
+
+        if (not @split or ref $split[0] or grep /\0/, @split) {
+            warn "Invalid value in $filename line $linenr.\n";
+            next;
+        }
+
+        my ($ids, $p, $desc, @extra) = @split;
+
+        my @addon_ids;
+        my %tags;
+
+        my $compat = 0;
+        if (@split == 1 and ref $split[0]) {
+            $compat = 1;
+        } else {
+            for (@extra) {
+                if (/^\+(.*)/) {
+                    push @addon_ids, $1;
+                } elsif (/^\#(\w+)(=(.*))?/) {
+                    $tags{$1} = $2 ? $3 : 1;
+                } else {
+                    $compat = 1;
+                    last;
+                }
+            }
+        }
+
+        if ($compat) {
+            $warnings++;
+            warn "$filename line $linenr: can't parse as new format; assuming old format.\n" if $warnings < 4;
+            warn "Too many warnings; suppressing the rest. See UPGRADING.md for instructions.\n" if $warnings == 4;
+
+            ($ids, $p, $desc) = split " ", $line, 3;
+
+            @addon_ids = ();
+            unshift @addon_ids, $1 while $desc =~ s/\s+ \+ (\S+)$//x;
+        }
+
+        my $canonical = join " ", map RevBank::Prompt::reconstruct($_), $ids, $p, $desc, @extra;
+
+        my @ids = split /,/, $ids;
+
+        $p ||= "invalid";
+        $desc ||= "(no description)";
+
+        my ($price, $contra) = split /\@/, $p, 2;
+
+        my $sign = $price =~ s/^-// ? -1 : 1;
+        my $percent = $price =~ s/%$//;
+
+        if ($percent) {
+            if (grep !/^\+/, @ids) {
+                warn "Percentage invalid for non-addon at $filename line $linenr.\n";
+                next;
+            }
+            $price = 0 + $price;
+        } else {
+            $price = eval { parse_amount($price) };
+            if (not defined $price) {
+                warn "Invalid price for '$ids[0]' at $filename line $linenr.\n";
+                next;
+            }
+        }
+        for my $id (@ids) {
+            warn "Product '$id' redefined at $filename line $linenr (original at line $products{$id}{line}).\n" if exists $products{$id};
+
+            $products{$id} = {
+                id          => $ids[0],
+                price       => $sign * $price,
+                percent     => $percent,
+                description => $desc,
+                contra      => $contra || $default_contra,
+                _addon_ids  => \@addon_ids,
+                line        => $linenr,
+                tags        => \%tags,
+                config      => $canonical,
+            };
+        }
+    }
+
+    PRODUCT: for my $product (values %products) {
+        my %ids_seen = ($product->{id} => 1);
+        my @addon_ids = @{ $product->{_addon_ids} };
+
+        while (my $addon_id = shift @addon_ids) {
+            $addon_id = "+$addon_id" if exists $products{"+$addon_id"};
+
+            if ($ids_seen{$addon_id}++) {
+                warn "Infinite addon loop for '$product->{id}' at $filename line $product->{line}.\n";
+                next PRODUCT;
+            }
+
+            my $addon = $products{$addon_id};
+            if (not $addon) {
+                warn "Addon '$addon_id' does not exist for '$product->{id}' at $filename line $product->{line}.\n";
+                next PRODUCT;
+            }
+
+            push @{ $product->{addons} }, $addon;
+            push @addon_ids, @{ $addon->{_addon_ids} };
+        }
+    }
+
+    return $cache{$filename} = \%products;
+}
+
+1;
diff --git a/plugins/products b/plugins/products
index 7f92c6a..f02b253 100644
--- a/plugins/products
+++ b/plugins/products
@@ -1,134 +1,8 @@
 #!perl
+use RevBank::Products qw(read_products);
 
 HELP1 "<productID>" => "Add a product to pending transaction";
 
-my $filename = 'revbank.products';
-my $default_contra = '+sales/products';
-
-sub read_products() {
-    state %products;
-    state $mtime;
-
-    return \%products if $mtime and $mtime == -M $filename;
-    %products = ();
-    $mtime = -M $filename;
-
-    my $linenr = 0;
-    my $warnings = 0;
-
-    for my $line (slurp $filename) {
-        $linenr++;
-
-        next if $line =~ m[
-            ^\s*\#    # comment line
-            |
-            ^\s*$     # empty line, or only whitespace
-        ]x;
-
-        my @split = RevBank::Prompt::split_input($line);
-
-        if (not @split or ref $split[0] or grep /\0/, @split) {
-            warn "Invalid value in $filename line $linenr.\n";
-            next;
-        }
-
-        my ($ids, $p, $desc, @extra) = @split;
-
-        my @addon_ids;
-        my %tags;
-
-        my $compat = 0;
-        if (@split == 1 and ref $split[0]) {
-            $compat = 1;
-        } else {
-            for (@extra) {
-                if (/^\+(.*)/) {
-                    push @addon_ids, $1;
-                } elsif (/^\#(\w+)(=(.*))?/) {
-                    $tags{$1} = $2 ? $3 : 1;
-                } else {
-                    $compat = 1;
-                    last;
-                }
-            }
-        }
-
-        if ($compat) {
-            $warnings++;
-            warn "$filename line $linenr: can't parse as new format; assuming old format.\n" if $warnings < 4;
-            warn "Too many warnings; suppressing the rest. See UPGRADING.md for instructions.\n" if $warnings == 4;
-
-            ($ids, $p, $desc) = split " ", $line, 3;
-
-            @addon_ids = ();
-            unshift @addon_ids, $1 while $desc =~ s/\s+ \+ (\S+)$//x;
-        }
-
-        my @ids = split /,/, $ids;
-
-        $p ||= "invalid";
-        $desc ||= "(no description)";
-
-        my ($price, $contra) = split /\@/, $p, 2;
-
-        my $sign = $price =~ s/^-// ? -1 : 1;
-        my $percent = $price =~ s/%$//;
-
-        if ($percent) {
-            if (grep !/^\+/, @ids) {
-                warn "Percentage invalid for non-addon at $filename line $linenr.\n";
-                next;
-            }
-            $price = 0 + $price;
-        } else {
-            $price = eval { parse_amount($price) };
-            if (not defined $price) {
-                warn "Invalid price for '$ids[0]' at $filename line $linenr.\n";
-                next;
-            }
-        }
-        for my $id (@ids) {
-            warn "Product '$id' redefined at $filename line $linenr (original at line $products{$id}{line}).\n" if exists $products{$id};
-
-            $products{$id} = {
-                id          => $ids[0],
-                price       => $sign * $price,
-                percent     => $percent,
-                description => $desc,
-                contra      => $contra || $default_contra,
-                _addon_ids  => \@addon_ids,
-                line        => $linenr,
-                tags        => \%tags,
-            };
-        }
-    }
-
-    PRODUCT: for my $product (values %products) {
-        my %ids_seen = ($product->{id} => 1);
-        my @addon_ids = @{ $product->{_addon_ids} };
-
-        while (my $addon_id = shift @addon_ids) {
-            $addon_id = "+$addon_id" if exists $products{"+$addon_id"};
-
-            if ($ids_seen{$addon_id}++) {
-                warn "Infinite addon loop for '$product->{id}' at $filename line $product->{line}.\n";
-                next PRODUCT;
-            }
-
-            my $addon = $products{$addon_id};
-            if (not $addon) {
-                warn "Addon '$addon_id' does not exist for '$product->{id}' at $filename line $product->{line}.\n";
-                next PRODUCT;
-            }
-
-            push @{ $product->{addons} }, $addon;
-            push @addon_ids, @{ $addon->{_addon_ids} };
-        }
-    }
-
-    return \%products;
-}
-
 sub command :Tab(&tab) ($self, $cart, $command, @) {
     $command =~ /\S/ or return NEXT;
     $command =~ /^\+/ and return NEXT;