Backports various fixes and tests from Berry

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@yarnpkg/monorepo",
-  "packageManager": "yarn@6.0.0-rc.19",
+  "packageManager": "yarn@6.0.0-git.20260814.hash-4421e301548e85d07d894540f89adc1345b1374a",
   "scripts": {
     "codegen:daemon-types": "cargo run -p zpm --bin generate_daemon_types",
     "codegen:daemon-types:check": "cargo run -p zpm --bin generate_daemon_types -- --check",

packages/zpm-config/build.rs

@@ -105,6 +105,9 @@ struct Field {
     title: Option<String>,
     description: Option<String>,
     default: Option<Expression>,
+    /// Set on array fields that also accept a single item, which then gets
+    /// treated as a list of one (`supportedArchitectures`, for instance).
+    one_or_many: Option<bool>,
     property_aliases: Option<BTreeMap<String, Vec<String>>>,
     properties: Option<BTreeMap<String, Field>>,
     additional_keys: Option<Box<Field>>,
@@ -162,6 +165,7 @@ impl Field {
                         type_: field.get_type(),
                         aliases: field_aliases,
                         default: field_default,
+                        one_or_many: field.one_or_many.unwrap_or(false),
                     });
                 }
 
@@ -258,6 +262,7 @@ struct GeneratorField {
     type_: InternalType,
     aliases: Vec<String>,
     default: String,
+    one_or_many: bool,
 }
 
 struct Generator {
@@ -300,7 +305,13 @@ impl Generator {
                     writeln!(writer, "        #[serde(alias = \"{alias_camel_case}\")]").unwrap();
                 }
 
-                writeln!(writer, "        #[serde(default)] pub {lc_snake_name}: Partial<{}>,", type_.to_intermediate_type_string()).unwrap();
+                let deserialize_with = if field.one_or_many {
+                    ", deserialize_with = \"crate::deserialize_one_or_many\""
+                } else {
+                    ""
+                };
+
+                writeln!(writer, "        #[serde(default{deserialize_with})] pub {lc_snake_name}: Partial<{}>,", type_.to_intermediate_type_string()).unwrap();
             }
 
             writeln!(writer, "    }}").unwrap();
@@ -412,8 +423,17 @@ impl Generator {
                 let lc_snake_name
                     = name.to_case(Case::Snake);
 
+                // A one-or-many field is a single logical value, so the project
+                // configuration must replace the user one rather than extend it
+                // like regular list settings do.
+                let user_expr = if field.one_or_many {
+                    format!("if let Partial::Value(_) = &project.{lc_snake_name} {{ Partial::Missing }} else {{ user.{lc_snake_name} }}")
+                } else {
+                    format!("user.{lc_snake_name}")
+                };
+
                 let merge_expr
-                    = format!("MergeSettings::merge(context, user.{lc_snake_name}, project.{lc_snake_name}, {default})");
+                    = format!("MergeSettings::merge(context, {user_expr}, project.{lc_snake_name}, {default})");
 
                 if struct_name == &self.root_name {
                     writeln!(writer, "            {lc_snake_name}: {{").unwrap();

packages/zpm-config/schema.json

@@ -628,29 +628,27 @@
       "default": 5000
     },
     "supportedArchitectures": {
-      "type": "object",
-      "title": "SupportedArchitectures",
-      "description": "The list of architectures we need to download in the cache.",
-      "properties": {
-        "cpu": {
-          "type": "array",
-          "description": "List of CPU architectures to cover.",
-          "items": {
-            "type": "zpm_utils::Cpu"
-          }
-        },
-        "libc": {
-          "type": "array",
-          "description": "The list of standard C libraries to cover.",
-          "items": {
-            "type": "zpm_utils::Libc"
-          }
-        },
-        "os": {
-          "type": "array",
-          "description": "The list of operating systems to cover.",
-          "items": {
-            "type": "zpm_utils::Os"
+      "type": "array",
+      "oneOrMany": true,
+      "description": "The list of architectures we need to download in the cache. Can either be a single entry (whose fields are combined together as a cross product) or a list of entries (each entry being matched independently).",
+      "items": {
+        "type": "object",
+        "title": "SupportedArchitectures",
+        "properties": {
+          "cpu": {
+            "type": "crate::ArchitectureFilter<zpm_utils::Cpu>",
+            "description": "The CPU architecture (or list of architectures) to cover, or null to cover them all.",
+            "default": "current"
+          },
+          "libc": {
+            "type": "crate::ArchitectureFilter<zpm_utils::Libc>",
+            "description": "The standard C library (or list of libraries) to cover, or null to cover them all.",
+            "default": "current"
+          },
+          "os": {
+            "type": "crate::ArchitectureFilter<zpm_utils::Os>",
+            "description": "The operating system (or list of systems) to cover, or null to cover them all.",
+            "default": "current"
           }
         }
       }