feat(launch): M157 实例级启动参数（五项回落 + graphicsBackend 三态）

core: 新增 game/launch_overrides（LaunchOverrides 五项 All-Option + 三级回落 + 文本补丁校验）与 launch/overrides（拼装落位：全局 java.extra_args 进 user.jvm、实例 jvmArgs 进 override_jvm、gameArgs 进 user.game、memory 进 -Xmx、backend 进 --graphicsBackend 并复用既有版本门槛告警）；实例 schema 登记 launch.* 五键。

presenter: dto/LaunchArgsView+LaunchArgsPatch，主机侧读/写与门槛判定（backend_allowed），AppCommand::SetInstanceLaunchArgs。

cli: 新命令 instances launch-args（读/写/--clear），launch 装配链消费回落值。

app-iced: 实例详情页「启动参数」区（JVM/游戏参数、内存、Java、三态后端 chips + 灰化提示 + 保存/恢复），表单状态归 App、i18n 中英文案同步。

crates/core/src/launch/overrides.rs

@@ -0,0 +1,372 @@
+//! 实例级启动参数的**落位**：`ResolvedLaunch` → [`LaunchRequest`]。
+//!
+//! 三级回落本身在 [`crate::game::launch_overrides`]（纯计算）；本模块只回答「落到哪一段」，
+//! 规则与理由见 M157 的定案（叠加/冲突），这里给出可执行的对照表：
+//!
+//! | 生效值 | 落点 | 组装表 | 为什么在这儿 |
+//! |---|---|---|---|
+//! | 全局 `java.extra_args` | `user.jvm` | 第 7 项 | 基线：按“默认值”处理，可被清单参数抑制 |
+//! | 实例 `launch.jvmArgs` | `user.override_jvm` | 第 4 项 | 精调：最高优先级，`-Xmx`/编码/代理默认值全被它抑制 |
+//! | 实例 `launch.gameArgs` | `user.game` | 第 32 项 | 最后追加，可覆盖前面一切游戏参数 |
+//! | `memoryMb`（已回落） | `memory.max_mb` | 第 5 项 | `-Xmx` 只从这里长出来 |
+//! | `graphicsBackend` | `graphics_backend` | 第 31 项 | 仍过 `graphics_backend_allowed` 门槛，不放行给诊断告警 |
+//! | `javaPath` | **不进来** | — | Java 选择在调用方（`JavaSelection`），见标量注释 |
+//!
+//! # 两条必须一起读的结论
+//!
+//! 1. **追加，不替换**：全局与实例的 JVM 参数都下发。实例段在前、全局段在后，同名选项由 JVM
+//!    取后出现者——但注意组装表第 4 项在 `-Xmx` **之前**：实例文本里的 `-Xmx` 会抑制内存字段
+//!    产出的 `-Xmx`（这是「文本比字段更精确」的表达，不是 bug）；
+//! 2. **全局文本里的 `-Xmx` 不生效**：第 7 项晚于第 5 项，`-Xmx` 已被内存字段占住
+//!    （`add_default` 语义）。要改堆请用内存字段或实例 JVM 文本——写进注释与测试，别当特例。
+//!
+//! `javaPath` 不进 `LaunchRequest`：那份结构只收选好的 [`crate::launch::request::JavaSelection`]，
+//! 调用方用 `resolved.java_path` 决定「显式路径优先 / 自动挑」。
+
+use std::path::Path;
+
+use crate::game::launch_overrides::ResolvedLaunch;
+use crate::launch::command_builder::tokenize;
+use crate::launch::request::{LaunchRequest, MemoryOptions};
+
+/// 把三级回落后的生效值写进请求（覆盖 `user.*` / `memory` / `graphics_backend` 三处）。
+///
+/// 调用方在 [`crate::launch::adapter::build_request`] 之后调用一次即可；它**接管**这三处，
+/// 所以别在此之前再往 `user` 里塞东西（目前 CLI 与 GUI 都没有别的来源，契约就是这一段）。
+pub fn apply(request: &mut LaunchRequest, resolved: &ResolvedLaunch) {
+    request.user.jvm = tokens(resolved.global_jvm_args.as_deref());
+    request.user.override_jvm = tokens(resolved.instance_jvm_args.as_deref());
+    request.user.game = tokens(resolved.game_args.as_deref());
+    request.memory = MemoryOptions {
+        min_mb: request.memory.min_mb,
+        max_mb: Some(resolved.memory_mb),
+    };
+    request.graphics_backend = resolved.graphics_backend.flag_value().map(str::to_string);
+}
+
+/// 实例/全局给的显式 Java 路径（`None` = 调用方走自动挑）。
+#[must_use]
+pub fn java_binary(resolved: &ResolvedLaunch) -> Option<&Path> {
+    resolved.java_path.as_deref()
+}
+
+/// 版本能不能下发 `--graphicsBackend`：**解析过继承链的**版本 JSON + 游戏版本号。
+///
+/// `resolved_json` 必须是继承解析之后的那份（26.2 的 `lwjgl-vulkan` 在父层，
+/// 只看 loader 层会漏）。判据本身仍是 [`graphics_backend_allowed`] 一处实现——
+/// UI 与拼装链共用它，别在调用方再抄一遍能力位判断。
+#[must_use]
+pub fn backend_allowed(
+    version: &crate::launch::game_version::GameVersion,
+    resolved_json: &crate::game::VersionJson,
+) -> bool {
+    crate::launch::game_args::graphics_backend_allowed(
+        version,
+        crate::game::VersionCapabilities::from_json(resolved_json).has_vulkan_backend,
+    )
+}
+
+fn tokens(text: Option<&str>) -> Vec<String> {
+    text.map(tokenize).unwrap_or_default()
+}
+
+#[cfg(test)]
+mod tests {
+    use std::path::PathBuf;
+
+    use super::*;
+    use crate::game::launch_overrides::{
+        resolve, GlobalLaunchDefaults, GraphicsBackend, LaunchOverrides,
+    };
+    use crate::launch::args_table::{assemble, AssemblyWarning};
+    use crate::launch::game_version::GameVersion;
+    use crate::launch::platform::{OsFamily, PlatformCtx};
+    use crate::launch::request::{
+        AuthPlaceholders, InstanceInfo, JavaSelection, LaunchDirs, LauncherInfo, Log4jOptions,
+        ManifestArgs, OptimizationOptions,
+    };
+
+    fn request(version: &str) -> LaunchRequest {
+        LaunchRequest {
+            instance: InstanceInfo {
+                id: "inst-1".to_string(),
+                name: version.to_string(),
+                version: GameVersion::parse(version),
+                version_type: "release".to_string(),
+            },
+            launcher: LauncherInfo {
+                name: "UnluckyLauncher".to_string(),
+                version: "0.2.2".to_string(),
+            },
+            java: JavaSelection::new("C:/java/bin/java.exe", 21, 64),
+            memory: MemoryOptions {
+                min_mb: None,
+                max_mb: None,
+            },
+            manifest: ManifestArgs {
+                main_class: Some("net.minecraft.client.main.Main".to_string()),
+                ..ManifestArgs::default()
+            },
+            dirs: LaunchDirs {
+                game_dir: PathBuf::from("C:/mc"),
+                primary_jar: PathBuf::from("C:/mc/versions/x/x.jar"),
+                ..LaunchDirs::default()
+            },
+            classpath: vec![PathBuf::from("C:/mc/libraries/a.jar")],
+            auth: AuthPlaceholders::default(),
+            log4j: Log4jOptions {
+                enabled: false,
+                ..Log4jOptions::default()
+            },
+            optimization: OptimizationOptions {
+                enabled: false,
+                physical_memory_mb: None,
+            },
+            language: "zh-CN".to_string(),
+            ..LaunchRequest::default()
+        }
+    }
+
+    fn ctx() -> PlatformCtx {
+        PlatformCtx::new(OsFamily::Windows, "x86_64")
+    }
+
+    fn argvs(req: &LaunchRequest) -> Vec<String> {
+        assemble(req, &ctx()).expect("组装应成功").args
+    }
+
+    fn position(args: &[String], needle: &str) -> Option<usize> {
+        args.iter().position(|arg| arg == needle)
+    }
+
+    /// **叠加规则**：实例段在 `-Xmx` 之前、全局段在之后；两段都下发（不替换）。
+    #[test]
+    fn instance_and_global_jvm_args_stack_in_order() {
+        let instance = LaunchOverrides {
+            jvm_args: Some("-XX:+UseG1GC".to_string()),
+            ..LaunchOverrides::default()
+        };
+        let global = GlobalLaunchDefaults {
+            jvm_args: Some("-Xss4m".to_string()),
+            ..GlobalLaunchDefaults::default()
+        };
+        let resolved = resolve(Some(&instance), &global);
+        let mut req = request("1.20.4");
+        apply(&mut req, &resolved);
+        let args = argvs(&req);
+
+        let instance_at = position(&args, "-XX:+UseG1GC").expect("实例参数要下发");
+        let memory_at = position(&args, "-Xmx2048m").expect("内存字段要产 -Xmx");
+        let global_at = position(&args, "-Xss4m").expect("全局参数要下发");
+        assert!(
+            instance_at < memory_at,
+            "实例段（override_jvm）必须在 -Xmx 之前：{args:?}"
+        );
+        assert!(
+            global_at > memory_at,
+            "全局段（user.jvm）在 -Xmx 之后（基线不抢内存字段）：{args:?}"
+        );
+    }
+
+    /// **-Xmx 冲突**：实例文本写 `-Xmx` ⇒ 内存字段不再产出（文本赢）；全局文本写 `-Xmx` ⇒ 被内存字段抑制。
+    #[test]
+    fn xmx_conflict_follows_the_assembly_order() {
+        let instance = LaunchOverrides {
+            jvm_args: Some("-Xmx3g".to_string()),
+            ..LaunchOverrides::default()
+        };
+        let resolved = resolve(Some(&instance), &GlobalLaunchDefaults::default());
+        let mut req = request("1.20.4");
+        apply(&mut req, &resolved);
+        let args = argvs(&req);
+        assert!(
+            args.iter().any(|arg| arg == "-Xmx3g"),
+            "实例文本的 -Xmx 必须生效：{args:?}"
+        );
+        assert!(
+            !args.iter().any(|arg| arg == "-Xmx2048m"),
+            "内存字段的 -Xmx 必须被抑制：{args:?}"
+        );
+
+        let resolved = resolve(None, &GlobalLaunchDefaults::with_jvm_args("-Xmx3g"));
+        let mut req = request("1.20.4");
+        apply(&mut req, &resolved);
+        let args = argvs(&req);
+        assert!(
+            args.iter().any(|arg| arg == "-Xmx2048m"),
+            "全局文本的 -Xmx 不生效（第 7 项晚于第 5 项）：{args:?}"
+        );
+        assert!(!args.iter().any(|arg| arg == "-Xmx3g"), "{args:?}");
+    }
+
+    /// 内存三级回落落进 `-Xmx`：实例 → 全局 → 默认。
+    #[test]
+    fn memory_falls_back_into_xmx() {
+        let global = GlobalLaunchDefaults {
+            memory_mb: Some(6144),
+            ..GlobalLaunchDefaults::default()
+        };
+        let instance = LaunchOverrides {
+            memory_mb: Some(8192),
+            ..LaunchOverrides::default()
+        };
+        for (overrides, expected) in [(Some(instance), "-Xmx8192m"), (None, "-Xmx6144m")] {
+            let resolved = resolve(overrides.as_ref(), &global);
+            let mut req = request("1.20.4");
+            apply(&mut req, &resolved);
+            assert!(
+                argvs(&req).iter().any(|arg| arg == expected),
+                "期望 {expected}"
+            );
+        }
+        let resolved = resolve(None, &GlobalLaunchDefaults::default());
+        let mut req = request("1.20.4");
+        apply(&mut req, &resolved);
+        assert!(argvs(&req).iter().any(|arg| arg == "-Xmx2048m"));
+    }
+
+    /// 游戏参数最后追加（可覆盖前面一切游戏参数）。
+    #[test]
+    fn game_args_land_at_the_tail() {
+        let instance = LaunchOverrides {
+            game_args: Some("--fullscreen --width 1920".to_string()),
+            ..LaunchOverrides::default()
+        };
+        let resolved = resolve(Some(&instance), &GlobalLaunchDefaults::default());
+        let mut req = request("1.20.4");
+        apply(&mut req, &resolved);
+        let args = argvs(&req);
+        let tail = &args[args.len() - 3..];
+        assert_eq!(tail, ["--fullscreen", "--width", "1920"], "{args:?}");
+    }
+
+    /// **版本门槛**：26.2-snapshot-2+ 才下发；老版本不下发但必须给诊断告警（不静默）。
+    #[test]
+    fn graphics_backend_is_version_gated_with_a_warning() {
+        let instance = LaunchOverrides {
+            graphics_backend: Some(GraphicsBackend::Vulkan),
+            ..LaunchOverrides::default()
+        };
+        let resolved = resolve(Some(&instance), &GlobalLaunchDefaults::default());
+
+        let mut supported = request("26.2-snapshot-2");
+        apply(&mut supported, &resolved);
+        let command = assemble(&supported, &ctx()).expect("组装");
+        let at = position(&command.args, "--graphicsBackend").expect("支持版本要下发");
+        assert_eq!(command.args[at + 1], "vulkan");
+        assert!(
+            !command
+                .warnings
+                .iter()
+                .any(|warning| matches!(warning, AssemblyWarning::GraphicsBackendSkipped { .. })),
+            "支持版本不该有跳过告警：{:?}",
+            command.warnings
+        );
+
+        let mut old = request("1.20.4");
+        apply(&mut old, &resolved);
+        let command = assemble(&old, &ctx()).expect("组装");
+        assert!(
+            !command.args.iter().any(|arg| arg == "--graphicsBackend"),
+            "老版本不许下发：{:?}",
+            command.args
+        );
+        assert!(
+            command
+                .warnings
+                .iter()
+                .any(|warning| matches!(warning, AssemblyWarning::GraphicsBackendSkipped { .. })),
+            "跳过必须留诊断：{:?}",
+            command.warnings
+        );
+    }
+
+    /// `default` = 不下发、不告警（三态里的「跟随游戏默认」）。
+    #[test]
+    fn default_backend_emits_nothing() {
+        for instance in [None, Some(LaunchOverrides::default())] {
+            let resolved = resolve(instance.as_ref(), &GlobalLaunchDefaults::default());
+            let mut req = request("26.2");
+            apply(&mut req, &resolved);
+            let command = assemble(&req, &ctx()).expect("组装");
+            assert!(!command.args.iter().any(|arg| arg == "--graphicsBackend"));
+            assert!(command.warnings.is_empty(), "{:?}", command.warnings);
+        }
+    }
+
+    /// 启动器自带的 `--fullscreen`（第 29 项）与实例游戏参数共存：实例在最后，可覆盖。
+    #[test]
+    fn instance_game_args_win_over_launcher_defaults() {
+        let instance = LaunchOverrides {
+            game_args: Some("--fullscreen".to_string()),
+            ..LaunchOverrides::default()
+        };
+        let resolved = resolve(Some(&instance), &GlobalLaunchDefaults::default());
+        let mut req = request("1.20.4");
+        req.fullscreen = true;
+        apply(&mut req, &resolved);
+        let args = argvs(&req);
+        assert_eq!(
+            args.iter()
+                .filter(|arg| arg.as_str() == "--fullscreen")
+                .count(),
+            2,
+            "两处都给 --fullscreen，由 MC 取后者（实例段在最后）：{args:?}"
+        );
+        assert_eq!(args.last().map(String::as_str), Some("--fullscreen"));
+        assert!(
+            position(&args, "net.minecraft.client.main.Main").unwrap() < args.len() - 1,
+            "实例游戏参数必须在主类之后"
+        );
+    }
+
+    /// Java 路径不进请求、只作为调用方的选择依据。
+    #[test]
+    fn java_path_is_a_scalar_for_the_caller() {
+        let instance = LaunchOverrides {
+            java_path: Some(PathBuf::from("D:/jdk21/bin/java.exe")),
+            ..LaunchOverrides::default()
+        };
+        let resolved = resolve(Some(&instance), &GlobalLaunchDefaults::default());
+        assert_eq!(
+            java_binary(&resolved),
+            Some(Path::new("D:/jdk21/bin/java.exe"))
+        );
+        let mut req = request("1.20.4");
+        let before = req.java.binary.clone();
+        apply(&mut req, &resolved);
+        assert_eq!(req.java.binary, before, "apply 不改 Java 选择");
+    }
+
+    /// `backend_allowed`：继承解析后的库表 + 版本门限，两条判据的**唯一组合入口**。
+    ///
+    /// 它是 UI 灰化与拼装链共用的那一格：调用方只负责把「继承解析后的版本 JSON」和
+    /// 「游戏版本号」递进来，不许自己拼 `has_vulkan_backend && is_at_least(..)`。
+    #[test]
+    fn backend_allowed_combines_capability_and_threshold() {
+        use crate::game::VersionJson;
+
+        let with_vulkan = VersionJson::from_json_str(
+            r#"{"id":"x","libraries":[{"name":"org.lwjgl:lwjgl-vulkan:3.4.3"}]}"#,
+        )
+        .expect("解析");
+        let without = VersionJson::from_json_str(r#"{"id":"x"}"#).expect("解析");
+
+        // 可解析版本：精确门限说了算（库表只作周快照兜底）。
+        assert!(backend_allowed(
+            &GameVersion::parse("26.2-snapshot-2"),
+            &without
+        ));
+        assert!(!backend_allowed(
+            &GameVersion::parse("26.2-snapshot-1"),
+            &with_vulkan
+        ));
+        assert!(!backend_allowed(
+            &GameVersion::parse("1.20.4"),
+            &with_vulkan
+        ));
+        // 周快照：看库表。
+        assert!(backend_allowed(&GameVersion::parse("26w14a"), &with_vulkan));
+        assert!(!backend_allowed(&GameVersion::parse("26w14a"), &without));
+    }
+}