diff --git a/apps/ai-game-creator-shell/src-tauri/src/project/manifest.rs b/apps/ai-game-creator-shell/src-tauri/src/project/manifest.rs
index 37c757da8..fbd020f82 100644
--- a/apps/ai-game-creator-shell/src-tauri/src/project/manifest.rs
+++ b/apps/ai-game-creator-shell/src-tauri/src/project/manifest.rs
@@ -1608,6 +1608,8 @@ pub(crate) fn read_manifest(path: &Path) -> Result<GameCreationAppManifest, Stri
         .map_err(|error| format!("读取 {label} 失败：{}: {error}", source_path.display()))?;
     let manifest: GameCreationAppManifest = serde_json::from_str(&payload)
         .map_err(|error| format!("解析 {label} 失败：{}: {error}", source_path.display()))?;
+    validate_manifest_schema_version(&manifest.schema_version)
+        .map_err(|error| format!("校验 {label} schema 版本失败：{error}"))?;
     validate_manifest_godot_project_root(manifest.godot_project_root.as_deref())
         .map_err(|error| format!("校验 {label} Godot 项目根失败：{error}"))?;
     validate_game_iteration_versions(&manifest.versions)
@@ -1615,6 +1617,32 @@ pub(crate) fn read_manifest(path: &Path) -> Result<GameCreationAppManifest, Stri
     Ok(manifest)
 }
 
+/// manifest 的 `schemaVersion` 门：只接受当前唯一已知版本，未知版本一律失败关闭。
+///
+/// 为什么必须在**读侧**校验：manifest 是项目的持久化业务真相，而 [`write_manifest_locked`] 会把
+/// 整个 `GameCreationAppManifest` 重新序列化后覆盖落盘。也就是说「读一次 + 任意一次写」等价于
+/// 按**本客户端已知的结构**全量重写该文件。读到未知版本还继续，旧客户端就会把新版本文件降级写回，
+/// 静默丢掉新版本的字段与语义；这跟同批新增的资源布局 sidecar（[`validate_resource_layout`]
+/// 对未知 `schemaVersion` 直接报「不支持的资源布局 schema」）是同一条失败关闭口径。
+///
+/// 前向兼容取舍：这里刻意**不做**「接受未来版本 + 读时就地升级」。就地升级需要迁移函数和迁移测试，
+/// 而当前并不存在 v2 的定义，凭空写一个「升级」只能把未知数据改写成当前版本的形状——那正是本次
+/// 要修掉的静默接受。代价是明确的：未来发 v2 时，旧客户端会报「schemaVersion 不受支持」并拒绝打开，
+/// 用户拿到的是可行动的「请升级客户端」，而不是一个已经被写坏的项目。
+///
+/// 与 [`validate_game_iteration_versions`] 等一样，读侧（[`read_manifest`]）和写侧
+/// （[`write_manifest_locked`]）都调用本函数：读侧保证不把未知版本当成已知版本用，写侧保证本客户端
+/// 永远不会把未知版本写进项目。
+fn validate_manifest_schema_version(schema_version: &str) -> Result<(), String> {
+    let supported = shared_contracts::game_creation_app::GAME_CREATION_APP_MANIFEST_SCHEMA_VERSION;
+    if schema_version != supported {
+        return Err(format!(
+            "manifest schemaVersion 不受支持：{schema_version}（当前支持 {supported}）"
+        ));
+    }
+    Ok(())
+}
+
 fn install_manifest_temp_with<F>(
     path: &Path,
     temp_path: &Path,
@@ -1721,6 +1749,8 @@ fn write_manifest_locked(
     manifest: &GameCreationAppManifest,
     allowed_version_removals: &dyn Fn(&GameCreationAppManifest) -> Vec<String>,
 ) -> Result<(), String> {
+    validate_manifest_schema_version(&manifest.schema_version)
+        .map_err(|error| format!("校验 manifest schema 版本失败：{error}"))?;
     validate_game_iteration_versions(&manifest.versions)
         .map_err(|error| format!("校验 manifest 项目版本失败：{error}"))?;
     let payload = serde_json::to_string_pretty(manifest)
diff --git a/apps/ai-game-creator-shell/src-tauri/src/project/manifest/import_tests.rs b/apps/ai-game-creator-shell/src-tauri/src/project/manifest/import_tests.rs
index b226c4158..5a1ef2390 100644
--- a/apps/ai-game-creator-shell/src-tauri/src/project/manifest/import_tests.rs
+++ b/apps/ai-game-creator-shell/src-tauri/src/project/manifest/import_tests.rs
@@ -396,3 +396,77 @@ fn rejects_non_godot_directory_without_writing_agent_metadata() {
     assert!(!root.join(".agent").exists());
     fs::remove_dir_all(root).ok();
 }
+
+fn write_raw_manifest_fixture(workspace: &Path, payload: &serde_json::Value) -> (PathBuf, String) {
+    let manifest_path = workspace.join(".agent/manifest.json");
+    fs::create_dir_all(manifest_path.parent().expect("manifest parent"))
+        .expect("create manifest parent");
+    let fixture = format!(
+        "{}\n",
+        serde_json::to_string_pretty(payload).expect("serialize manifest fixture")
+    );
+    fs::write(&manifest_path, &fixture).expect("write manifest fixture");
+    (manifest_path, fixture)
+}
+
+/// 读侧必须明确接受当前版本：只有「拒绝未知版本」的负向断言挡不住「无条件拒绝」这种改法。
+#[test]
+fn manifest_read_accepts_the_current_schema_version() {
+    let workspace = godot_import_test_path("current-manifest-schema");
+    let mut manifest = new_game_creation_app_manifest("schema-project", "Schema");
+    manifest.goal = Some("做一个像素动作原型".to_string());
+    manifest.godot_project_root = Some("game-source".to_string());
+    assert_eq!(
+        manifest.schema_version,
+        shared_contracts::game_creation_app::GAME_CREATION_APP_MANIFEST_SCHEMA_VERSION
+    );
+    let manifest_path = workspace.join(".agent/manifest.json");
+    write_manifest(&manifest_path, &manifest).expect("write current manifest");
+
+    let read = read_manifest(&manifest_path).expect("current schemaVersion must be accepted");
+
+    // 全字段回读相等，同时证明 `deny_unknown_fields` 没有把已知字段/可选字段一起拒掉。
+    assert_eq!(read, manifest);
+    assert_eq!(read.project_id, "schema-project");
+    assert_eq!(read.godot_project_root.as_deref(), Some("game-source"));
+    fs::remove_dir_all(workspace).ok();
+}
+
+/// 读到未知 `schemaVersion` 必须失败关闭，而且**只读失败**：不能在失败路径上顺手把
+/// 「新版本文件」按本客户端的结构重写一遍。
+#[test]
+fn manifest_read_rejects_an_unsupported_schema_version_without_rewriting_the_file() {
+    let workspace = godot_import_test_path("unsupported-manifest-schema");
+    let mut payload =
+        serde_json::to_value(new_game_creation_app_manifest("schema-project", "Schema"))
+            .expect("serialize manifest fixture");
+    payload["schemaVersion"] = serde_json::json!("game-creation-app.manifest.v2");
+    let (manifest_path, fixture) = write_raw_manifest_fixture(&workspace, &payload);
+
+    let error = read_manifest(&manifest_path)
+        .expect_err("an unsupported manifest schemaVersion must fail closed");
+
+    assert!(error.contains("schemaVersion"), "unexpected error: {error}");
+    assert!(error.contains("game-creation-app.manifest.v2"), "{error}");
+    assert_eq!(
+        fs::read_to_string(&manifest_path).expect("re-read manifest fixture"),
+        fixture
+    );
+    fs::remove_dir_all(workspace).ok();
+}
+
+/// 写侧同一口径：本客户端永远不许把未知 `schemaVersion` 写进项目，且失败发生在落盘之前。
+#[test]
+fn manifest_write_rejects_an_unsupported_schema_version_before_touching_the_file() {
+    let workspace = godot_import_test_path("unsupported-manifest-write-schema");
+    let manifest_path = workspace.join(".agent/manifest.json");
+    let mut manifest = new_game_creation_app_manifest("schema-project", "Schema");
+    manifest.schema_version = "game-creation-app.manifest.v2".to_string();
+
+    let error = write_manifest(&manifest_path, &manifest)
+        .expect_err("writing an unsupported manifest schemaVersion must fail closed");
+
+    assert!(error.contains("schemaVersion"), "unexpected error: {error}");
+    assert!(!manifest_path.exists());
+    fs::remove_dir_all(workspace).ok();
+}