fix(boot): name an outdated system web engine on the startup failure page (#2587)

On macOS 11 with the original Safari 14 the system web engine cannot parse the
Safari 16 bundle, and startup failed with only "Could not load startup script".
When the engine lacks Safari 16 features, the failure page now says the system
Safari (or WebKitGTK) is too old and how to update it.

Refs #2008

public/boot.js

@@ -12,6 +12,10 @@
         manual: "无法复制。请选择下方详情并手动复制。",
         details: "启动错误详情",
         timeout: "启动未在 30 秒内完成。",
+        outdatedMac:
+          "这台 Mac 的 Safari 版本过旧：OpenIDEA 的界面使用系统的 Safari 网页引擎，需要 Safari 16 或更高版本。请在「系统偏好设置 › 软件更新」中更新 Safari，然后重新打开 OpenIDEA。",
+        outdated:
+          "系统的 WebKitGTK 版本过旧：OpenIDEA 需要较新的 WebKitGTK（webkit2gtk-4.1）。请通过系统的包管理器更新后重新打开 OpenIDEA。",
       }
     : {
         title: "OpenIDEA could not start",
@@ -22,7 +26,21 @@
         manual: "Could not copy. Select the details below and copy them.",
         details: "Startup error details",
         timeout: "Startup did not finish within 30 seconds.",
+        outdatedMac:
+          "Safari on this Mac is too old: OpenIDEA's interface runs on the system's Safari web engine and needs Safari 16 or later. Update Safari in System Preferences › Software Update, then open OpenIDEA again.",
+        outdated:
+          "The system's WebKitGTK is too old: OpenIDEA needs a recent WebKitGTK (webkit2gtk-4.1). Update it with your package manager, then open OpenIDEA again.",
       };
+  // The bundle targets Safari 16 (vite.config.ts); an older system web engine can't even
+  // parse it. Container queries came with Safari 16, and WebKit's user agent doesn't name
+  // its version. Unknown (no CSS.supports) counts as current.
+  const outdated = () => {
+    try {
+      return typeof window.CSS?.supports === "function" && !window.CSS.supports("container-type", "inline-size");
+    } catch {
+      return false;
+    }
+  };
   let failed = false;
   let ready = false;
   const describe = (reason) => {
@@ -55,7 +73,9 @@
       const title = document.createElement("h1");
       title.textContent = text.title;
       const hint = document.createElement("p");
-      hint.textContent = text.report;
+      hint.textContent = outdated()
+        ? `${/Mac/.test(navigator.userAgent) ? text.outdatedMac : text.outdated} ${text.report}`
+        : text.report;
       const details = document.createElement("textarea");
       details.readOnly = true;
       details.setAttribute("aria-label", text.details);

src/platform/boot.test.ts

@@ -190,3 +190,26 @@ it("preserves Safari error messages when its stack only lists locations", () =>
   expect(document.querySelector("textarea")?.value).toContain("SyntaxError: Unsupported regular expression");
   expect(document.querySelector("textarea")?.value).toContain(error.stack);
 });
+
+it("names an outdated system web engine as the cause", () => {
+  const supports = vi.fn(() => false);
+  vi.stubGlobal("CSS", { supports });
+  vi.spyOn(navigator, "userAgent", "get").mockReturnValue(
+    "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko)",
+  );
+  window.dispatchEvent(new ErrorEvent("error", { error: new SyntaxError("Unexpected token '.'") }));
+  const hint = document.querySelector("#boot-error p")?.textContent;
+  expect(supports).toHaveBeenCalledWith("container-type", "inline-size");
+  expect(hint).toContain("needs Safari 16 or later");
+  expect(hint).toContain("Software Update");
+  vi.unstubAllGlobals();
+});
+
+it("keeps the plain report hint on a current engine", () => {
+  vi.stubGlobal("CSS", { supports: () => true });
+  window.dispatchEvent(new ErrorEvent("error", { error: new Error("startup failed") }));
+  expect(document.querySelector("#boot-error p")?.textContent).toBe(
+    "Copy the details below and include them in a GitHub issue.",
+  );
+  vi.unstubAllGlobals();
+});