diff --git a/definitions/manifest-schema.xsd b/definitions/manifest-schema.xsd
new file mode 100644
index 0000000..c8ca0c2
--- /dev/null
+++ b/definitions/manifest-schema.xsd
@@ -0,0 +1,125 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  Copyright (C) 2026 Moko Consulting <hello@mokoconsulting.tech>
+  SPDX-License-Identifier: GPL-3.0-or-later
+
+  MokoStandards Manifest Schema v1.0
+  Defines the structure of .mokogitea/manifest.xml
+
+  Validate: xmllint - -schema definitions/manifest-schema.xsd .mokogitea/manifest.xml
+-->
+<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
+           xmlns:moko="https://standards.mokoconsulting.tech/moko-platform/1.0"
+           targetNamespace="https://standards.mokoconsulting.tech/moko-platform/1.0"
+           elementFormDefault="qualified">
+
+  <!-- Root element -->
+  <xs:element name="moko-platform">
+    <xs:complexType>
+      <xs:sequence>
+        <xs:element name="identity" type="moko:identityType"/>
+        <xs:element name="governance" type="moko:governanceType"/>
+        <xs:element name="build" type="moko:buildType"/>
+        <xs:element name="deploy" type="moko:deployType" minOccurs="0"/>
+      </xs:sequence>
+      <xs:attribute name="schema-version" type="xs:string" use="required"/>
+    </xs:complexType>
+  </xs:element>
+
+  <!-- Identity block -->
+  <xs:complexType name="identityType">
+    <xs:sequence>
+      <xs:element name="name" type="xs:string"/>
+      <xs:element name="org" type="xs:string"/>
+      <xs:element name="description" type="xs:string"/>
+      <xs:element name="version" type="moko:versionType"/>
+      <xs:element name="license" type="moko:licenseType"/>
+    </xs:sequence>
+  </xs:complexType>
+
+  <!-- Version format: XX.YY.ZZ -->
+  <xs:simpleType name="versionType">
+    <xs:restriction base="xs:string">
+      <xs:pattern value="\d{2}\.\d{2}\.\d{2}"/>
+    </xs:restriction>
+  </xs:simpleType>
+
+  <!-- License with SPDX attribute -->
+  <xs:complexType name="licenseType">
+    <xs:simpleContent>
+      <xs:extension base="xs:string">
+        <xs:attribute name="spdx" type="xs:string" use="required"/>
+      </xs:extension>
+    </xs:simpleContent>
+  </xs:complexType>
+
+  <!-- Governance block -->
+  <xs:complexType name="governanceType">
+    <xs:sequence>
+      <xs:element name="platform" type="moko:platformType"/>
+      <xs:element name="standards-version" type="moko:versionType"/>
+      <xs:element name="standards-source" type="xs:anyURI"/>
+      <xs:element name="last-synced" type="xs:dateTime" minOccurs="0"/>
+    </xs:sequence>
+  </xs:complexType>
+
+  <!-- Allowed platform values -->
+  <xs:simpleType name="platformType">
+    <xs:restriction base="xs:string">
+      <xs:enumeration value="joomla"/>
+      <xs:enumeration value="dolibarr"/>
+      <xs:enumeration value="go"/>
+      <xs:enumeration value="node"/>
+      <xs:enumeration value="rust"/>
+      <xs:enumeration value="python"/>
+      <xs:enumeration value="generic"/>
+    </xs:restriction>
+  </xs:simpleType>
+
+  <!-- Build block -->
+  <xs:complexType name="buildType">
+    <xs:sequence>
+      <xs:element name="language" type="moko:languageType"/>
+      <xs:element name="package-type" type="moko:packageType"/>
+      <xs:element name="entry-point" type="xs:string"/>
+    </xs:sequence>
+  </xs:complexType>
+
+  <!-- Allowed languages -->
+  <xs:simpleType name="languageType">
+    <xs:restriction base="xs:string">
+      <xs:enumeration value="PHP"/>
+      <xs:enumeration value="Go"/>
+      <xs:enumeration value="JavaScript"/>
+      <xs:enumeration value="TypeScript"/>
+      <xs:enumeration value="Rust"/>
+      <xs:enumeration value="Python"/>
+      <xs:enumeration value="HCL"/>
+      <xs:enumeration value="Shell"/>
+    </xs:restriction>
+  </xs:simpleType>
+
+  <!-- Allowed package types -->
+  <xs:simpleType name="packageType">
+    <xs:restriction base="xs:string">
+      <xs:enumeration value="joomla-extension"/>
+      <xs:enumeration value="dolibarr"/>
+      <xs:enumeration value="application"/>
+      <xs:enumeration value="library"/>
+      <xs:enumeration value="mcp-server"/>
+      <xs:enumeration value="generic"/>
+    </xs:restriction>
+  </xs:simpleType>
+
+  <!-- Deploy block (optional) -->
+  <xs:complexType name="deployType">
+    <xs:sequence>
+      <xs:element name="source-dir" type="xs:string" minOccurs="0"/>
+      <xs:element name="remote-subdir" type="xs:string" minOccurs="0"/>
+      <xs:element name="excludes" type="xs:string" minOccurs="0"/>
+      <xs:element name="dev-host" type="xs:string" minOccurs="0"/>
+      <xs:element name="demo-host" type="xs:string" minOccurs="0"/>
+    </xs:sequence>
+  </xs:complexType>
+
+</xs:schema>