Adding winapp manifest validate to validate appxmanifest.xml files

docs/cli-schema.json

@@ -547,7 +547,7 @@
       }
     },
     "manifest": {
-      "description": "Create and modify appxmanifest.xml files for package identity and MSIX packaging. Use 'manifest generate' to create a new manifest, or 'manifest update-assets' to regenerate app icons from a source image.",
+      "description": "Create and modify appxmanifest.xml files for package identity and MSIX packaging. Use 'manifest generate' to create a new manifest, 'manifest update-assets' to regenerate app icons from a source image, or 'manifest validate' to check if a manifest is valid.",
       "hidden": false,
       "subcommands": {
         "generate": {
@@ -766,6 +766,57 @@
               "recursive": false
             }
           }
+        },
+        "validate": {
+          "description": "Validate an AppxManifest.xml file against the schema",
+          "hidden": false,
+          "arguments": {
+            "manifest-path": {
+              "description": "Path to AppxManifest.xml or Package.appxmanifest file to validate",
+              "order": 0,
+              "hidden": false,
+              "valueType": "System.IO.FileInfo",
+              "hasDefaultValue": false,
+              "arity": {
+                "minimum": 1,
+                "maximum": 1
+              }
+            }
+          },
+          "options": {
+            "--quiet": {
+              "description": "Suppress progress messages",
+              "hidden": false,
+              "aliases": [
+                "-q"
+              ],
+              "valueType": "System.Boolean",
+              "hasDefaultValue": true,
+              "defaultValue": false,
+              "arity": {
+                "minimum": 0,
+                "maximum": 1
+              },
+              "required": false,
+              "recursive": false
+            },
+            "--verbose": {
+              "description": "Enable verbose output",
+              "hidden": false,
+              "aliases": [
+                "-v"
+              ],
+              "valueType": "System.Boolean",
+              "hasDefaultValue": true,
+              "defaultValue": false,
+              "arity": {
+                "minimum": 0,
+                "maximum": 1
+              },
+              "required": false,
+              "recursive": false
+            }
+          }
         }
       }
     },

docs/llm-context.md

@@ -93,7 +93,7 @@ Start here for initializing a Windows app with required setup. Sets up everythin
 - `--verbose` / `-v` - Enable verbose output
 ### `winapp manifest`
 
-Create and modify appxmanifest.xml files for package identity and MSIX packaging. Use 'manifest generate' to create a new manifest, or 'manifest update-assets' to regenerate app icons from a source image.
+Create and modify appxmanifest.xml files for package identity and MSIX packaging. Use 'manifest generate' to create a new manifest, 'manifest update-assets' to regenerate app icons from a source image, or 'manifest validate' to check if a manifest is valid.
 
 #### `winapp manifest generate`
 
@@ -125,6 +125,17 @@ Generate new assets for images referenced in an appxmanifest.xml from a single s
 - `--manifest` - Path to AppxManifest.xml file (default: search current directory)
 - `--quiet` / `-q` - Suppress progress messages
 - `--verbose` / `-v` - Enable verbose output
+
+#### `winapp manifest validate`
+
+Validate an AppxManifest.xml file against the schema
+
+**Arguments:**
+- `<manifest-path>` *(required)* - Path to AppxManifest.xml or Package.appxmanifest file to validate
+
+**Options:**
+- `--quiet` / `-q` - Suppress progress messages
+- `--verbose` / `-v` - Enable verbose output
 ### `winapp package`
 
 Create MSIX installer from your built app. Run after building your app. appxmanifest.xml is required for packaging - it must be in current working directory, passed as --manifest or be in the input folder. Use --cert devcert.pfx to sign for testing. Example: winapp package ./dist --manifest appxmanifest.xml --cert ./devcert.pfx

docs/usage.md

@@ -299,6 +299,39 @@ winapp manifest update-assets mylogo.png --manifest ./dist/appxmanifest.xml
 winapp manifest update-assets mylogo.png --verbose
 ```
 
+#### manifest validate
+
+Validate an AppxManifest.xml file against the official Windows App SDK schemas using MakeAppx.exe.
+
+```bash
+winapp manifest validate <manifest-path>
+```
+
+**Arguments:**
+
+- `manifest-path` - Path to AppxManifest.xml or Package.appxmanifest file to validate
+
+**Description:**
+
+Validates an AppxManifest.xml file to ensure it conforms to the official Microsoft MSIX schemas. The command:
+
+- Uses MakeAppx.exe from the Windows SDK BuildTools package for complete schema validation
+- Validates the XML structure, required elements, and attribute values against official schemas
+- Provides detailed error messages with line numbers
+- Suggests fixes for common validation errors (e.g., invalid Application Id format, Publisher format)
+
+The command automatically downloads the required Windows SDK BuildTools package if not already installed.
+
+**Examples:**
+
+```bash
+# Validate a manifest file
+winapp manifest validate ./appxmanifest.xml
+
+# Validate with verbose output
+winapp manifest validate ./appxmanifest.xml --verbose
+```
+
 ---
 
 ### cert