Add liberty_xref package-agnostic cross-reference mechanism

New tables: liberty_xref_type (text PK, package, sort_order),
liberty_xref_source (package column for direct equality filtering),
liberty_xref (data rows keyed by content_id, works for any package).
Sequence liberty_xref_seq and indices on content_id and package columns.

LibertyXref and LibertyXrefType classes provide the full store/load/step
mechanism. Contact and stock register their own source types against the
shared tables. Upgrade script 5.0.1.php creates the tables on existing installs.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

2 files changed, 103 insertions, 0 deletions

diff --git a/admin/schema_inc.php b/admin/schema_inc.php
index e2462d5..a77678f 100755
--- a/admin/schema_inc.php
+++ b/admin/schema_inc.php
@@ -218,6 +218,42 @@ $tables = [
 				, CONSTRAINT `lib_attachment_meta_title_ref` FOREIGN KEY (`meta_title_id`) REFERENCES `" . BIT_DB_PREFIX . "liberty_meta_titles` (`meta_title_id`) '
 ",
 
+	'liberty_xref_type'   => "
+	xref_type C(32) PRIMARY,
+	package C(20) NOTNULL,
+	title C(64),
+	sort_order I2,
+	role_id I4,
+	type_href C(256)
+",
+
+	'liberty_xref_source' => "
+	source C(20) PRIMARY,
+	package C(20) NOTNULL,
+	xref_type C(32),
+	cross_ref_title C(64),
+	multi I2,
+	role_id I4,
+	cross_ref_href C(256),
+	template C(32),
+	data X
+",
+
+	'liberty_xref'        => "
+	xref_id I8 PRIMARY,
+	content_id I8 NOTNULL,
+	source C(20),
+	xorder I2,
+	xref I8,
+	xkey C(32),
+	xkey_ext C(250),
+	data X,
+	start_date T,
+	last_update_date T,
+	entry_date T,
+	end_date T
+",
+
 ];
 
 global $gBitInstaller;
@@ -258,6 +294,9 @@ $indices = [
 	'lib_attachment_meta_idx'        => [ 'table' => 'liberty_attachment_meta_data', 'cols' => 'attachment_id', 'opts' => null ],
 	'lib_attachment_meta_type_idx'   => [ 'table' => 'liberty_attachment_meta_data', 'cols' => 'meta_type_id', 'opts' => null ],
 	'lib_attachment_meta_title_idx'  => [ 'table' => 'liberty_attachment_meta_data', 'cols' => 'meta_title_id', 'opts' => null ],
+	'liberty_xref_content_idx'       => [ 'table' => 'liberty_xref', 'cols' => 'content_id', 'opts' => null ],
+	'liberty_xref_source_pkg_idx'    => [ 'table' => 'liberty_xref_source', 'cols' => 'package', 'opts' => null ],
+	'liberty_xref_type_pkg_idx'      => [ 'table' => 'liberty_xref_type', 'cols' => 'package', 'opts' => null ],
 ];
 
 foreach( array_keys($constraints) AS $tableName ) {
@@ -280,6 +319,7 @@ $sequences = [
 	'liberty_structures_id_seq'  => [ 'start' => 4 ],
 	'liberty_meta_types_id_seq'  => [ 'start' => 1 ],
 	'liberty_meta_titles_id_seq' => [ 'start' => 1 ],
+	'liberty_xref_seq'           => [ 'start' => 1 ],
 ];
 $gBitInstaller->registerSchemaSequences( LIBERTY_PKG_NAME, $sequences );
 
diff --git a/admin/upgrades/5.0.1.php b/admin/upgrades/5.0.1.php
new file mode 100644
index 0000000..f20d190
--- /dev/null
+++ b/admin/upgrades/5.0.1.php
@@ -0,0 +1,63 @@
+<?php
+/**
+ * @package liberty
+ */
+
+global $gBitInstaller;
+
+$gBitInstaller->registerPackageUpgrade(
+	[
+		'package'     => 'liberty',
+		'version'     => '5.0.1',
+		'description' => 'Add liberty_xref tables: a package-agnostic cross-reference mechanism for attaching typed, multi-valued, date-tracked attributes to any liberty content.',
+	],
+	[
+		[ 'DATADICT' => [
+			[ 'CREATE' => [
+				'liberty_xref_type'   => "
+					xref_type C(32) PRIMARY,
+					package C(20) NOTNULL,
+					title C(64),
+					sort_order I2,
+					role_id I4,
+					type_href C(256)
+				",
+				'liberty_xref_source' => "
+					source C(20) PRIMARY,
+					package C(20) NOTNULL,
+					xref_type C(32),
+					cross_ref_title C(64),
+					multi I2,
+					role_id I4,
+					cross_ref_href C(256),
+					template C(32),
+					data X
+				",
+				'liberty_xref'        => "
+					xref_id I8 PRIMARY,
+					content_id I8 NOTNULL,
+					source C(20),
+					xorder I2,
+					xref I8,
+					xkey C(32),
+					xkey_ext C(250),
+					data X,
+					start_date T,
+					last_update_date T,
+					entry_date T,
+					end_date T
+				",
+			]],
+			[ 'CREATESEQUENCE' => [
+				[ 'liberty_xref_seq' ],
+			]],
+			[ 'CREATEINDEX' => [
+				[
+					'liberty_xref_content_idx'    => [ 'liberty_xref',        'content_id', null ],
+					'liberty_xref_source_pkg_idx' => [ 'liberty_xref_source', 'package',    null ],
+					'liberty_xref_type_pkg_idx'   => [ 'liberty_xref_type',   'package',    null ],
+				],
+			]],
+		]],
+	]
+);