Preserve native semantics in plugin links

apps/app/src/components/plugin/ExperimentalFileLink.test.tsx

@@ -56,7 +56,28 @@ describe("ExperimentalFileLink", () => {
     expect(openFilePreview).not.toHaveBeenCalled();
   });
 
-  it("does not dispatch a malformed target supplied across a JavaScript boundary", () => {
+  it("uses a scheme-safe href for a valid scheme-like file name", () => {
+    const openFilePreview = vi.fn(() => true);
+    render(
+      <MemoryRouter>
+        <AppNavigationHostProvider capabilities={{ openFilePreview }}>
+          <ExperimentalFileLink target={{ ...target, path: "vscode:foo" }}>
+            vscode:foo
+          </ExperimentalFileLink>
+        </AppNavigationHostProvider>
+      </MemoryRouter>,
+    );
+    const link = screen.getByRole("link", { name: "vscode:foo" });
+    expect(link.getAttribute("href")).toBe("./vscode%3Afoo");
+
+    fireEvent.click(link);
+    expect(openFilePreview).toHaveBeenCalledWith({
+      target: { ...target, path: "vscode:foo" },
+      location: null,
+    });
+  });
+
+  it("renders a malformed target supplied across a JavaScript boundary as inert", () => {
     const openFilePreview = vi.fn(() => true);
     render(
       <MemoryRouter>
@@ -67,7 +88,30 @@ describe("ExperimentalFileLink", () => {
         </AppNavigationHostProvider>
       </MemoryRouter>,
     );
-    fireEvent.click(screen.getByRole("link", { name: "invalid" }));
+    const invalid = screen.getByText("invalid");
+    expect(screen.queryByRole("link", { name: "invalid" })).toBeNull();
+    expect(invalid.getAttribute("href")).toBeNull();
+    fireEvent.click(invalid);
+    expect(openFilePreview).not.toHaveBeenCalled();
+  });
+
+  it("renders a path with an unpaired UTF-16 surrogate as inert", () => {
+    const openFilePreview = vi.fn(() => true);
+    render(
+      <MemoryRouter>
+        <AppNavigationHostProvider capabilities={{ openFilePreview }}>
+          <ExperimentalFileLink
+            target={{ ...target, path: String.fromCharCode(0xd800) }}
+          >
+            invalid Unicode
+          </ExperimentalFileLink>
+        </AppNavigationHostProvider>
+      </MemoryRouter>,
+    );
+    const invalid = screen.getByText("invalid Unicode");
+    expect(screen.queryByRole("link", { name: "invalid Unicode" })).toBeNull();
+    expect(invalid.getAttribute("href")).toBeNull();
+    fireEvent.click(invalid);
     expect(openFilePreview).not.toHaveBeenCalled();
   });
 });

apps/app/src/components/plugin/ExperimentalFileLink.tsx

@@ -61,8 +61,10 @@ export function ExperimentalFileLink({
     },
     [intent, navigation, onClick],
   );
+  const href =
+    intent === null ? undefined : `./${encodeURIComponent(intent.target.path)}`;
   const anchor = (
-    <RouteAnchor {...anchorProps} href={target.path} onClick={handleClick} />
+    <RouteAnchor {...anchorProps} href={href} onClick={handleClick} />
   );
 
   if (intent === null) return anchor;

apps/app/src/components/plugin/ExperimentalUrlLink.test.tsx

@@ -44,6 +44,74 @@ describe("ExperimentalUrlLink", () => {
     expect(openUrl).not.toHaveBeenCalled();
   });
 
+  it.each(["_blank", "preview-pane"])(
+    "leaves the explicit %s target native when the URL host would accept it",
+    (target) => {
+      const openUrl = vi.fn(() => true);
+      render(
+        <MemoryRouter>
+          <AppNavigationHostProvider capabilities={{ openUrl }}>
+            <ExperimentalUrlLink href="https://example.com" target={target}>
+              Example
+            </ExperimentalUrlLink>
+          </AppNavigationHostProvider>
+        </MemoryRouter>,
+      );
+      const link = screen.getByRole("link", { name: "Example" });
+      expect(link.getAttribute("target")).toBe(target);
+      expect(link.getAttribute("rel")).toBe("noopener noreferrer");
+      expect(fireEvent.click(link)).toBe(true);
+      expect(openUrl).not.toHaveBeenCalled();
+    },
+  );
+
+  it("preserves an explicit rel for a named target", () => {
+    render(
+      <MemoryRouter>
+        <ExperimentalUrlLink
+          href="https://example.com"
+          target="preview-pane"
+          rel="opener"
+        >
+          Example
+        </ExperimentalUrlLink>
+      </MemoryRouter>,
+    );
+    expect(
+      screen.getByRole("link", { name: "Example" }).getAttribute("rel"),
+    ).toBe("opener");
+  });
+
+  it("preserves rel tokens without sacrificing named-target isolation", () => {
+    render(
+      <MemoryRouter>
+        <ExperimentalUrlLink
+          href="https://example.com"
+          target="preview-pane"
+          rel="nofollow"
+        >
+          Example
+        </ExperimentalUrlLink>
+      </MemoryRouter>,
+    );
+    expect(
+      screen.getByRole("link", { name: "Example" }).getAttribute("rel"),
+    ).toBe("nofollow noopener noreferrer");
+  });
+
+  it("does not add new-context rel tokens to a same-context target", () => {
+    render(
+      <MemoryRouter>
+        <ExperimentalUrlLink href="https://example.com" target="_self">
+          Example
+        </ExperimentalUrlLink>
+      </MemoryRouter>,
+    );
+    expect(
+      screen.getByRole("link", { name: "Example" }).getAttribute("rel"),
+    ).toBeNull();
+  });
+
   it("routes internal links through browser history before URL preferences", () => {
     const openUrl = vi.fn(() => true);
     render(
@@ -62,4 +130,29 @@ describe("ExperimentalUrlLink", () => {
     expect(screen.getByText("Settings route")).toBeTruthy();
     expect(openUrl).not.toHaveBeenCalled();
   });
+
+  it("keeps an explicit target on an internal route native", () => {
+    const openUrl = vi.fn(() => true);
+    render(
+      <MemoryRouter initialEntries={["/"]}>
+        <RouteNavigationProvider>
+          <AppNavigationHostProvider capabilities={{ openUrl }}>
+            <ExperimentalUrlLink href="/settings" target="_blank">
+              Settings in new context
+            </ExperimentalUrlLink>
+            <Routes>
+              <Route path="/settings" element={<div>Settings route</div>} />
+            </Routes>
+          </AppNavigationHostProvider>
+        </RouteNavigationProvider>
+      </MemoryRouter>,
+    );
+    const link = screen.getByRole("link", {
+      name: "Settings in new context",
+    });
+    expect(link.getAttribute("target")).toBe("_blank");
+    expect(fireEvent.click(link)).toBe(true);
+    expect(screen.queryByText("Settings route")).toBeNull();
+    expect(openUrl).not.toHaveBeenCalled();
+  });
 });

apps/app/src/components/plugin/ExperimentalUrlLink.tsx

@@ -14,7 +14,8 @@ function shouldHandleUrlClick(
     event.ctrlKey ||
     event.metaKey ||
     event.shiftKey ||
-    event.currentTarget.hasAttribute("download")
+    event.currentTarget.hasAttribute("download") ||
+    event.currentTarget.hasAttribute("target")
   ) {
     return false;
   }
@@ -51,12 +52,40 @@ export function ExperimentalUrlLink({
     },
     [href, navigation, onClick],
   );
+  const normalizedTarget = target?.toLowerCase();
+  const opensNewBrowsingContext =
+    normalizedTarget !== undefined &&
+    normalizedTarget !== "" &&
+    normalizedTarget !== "_self" &&
+    normalizedTarget !== "_parent" &&
+    normalizedTarget !== "_top" &&
+    normalizedTarget !== "_unfencedtop";
+  const relTokens = rel?.split(/\s+/u).filter(Boolean) ?? [];
+  const normalizedRelTokens = relTokens.map((token) => token.toLowerCase());
+  const resolvedRel =
+    opensNewBrowsingContext && !normalizedRelTokens.includes("opener")
+      ? [
+          ...relTokens,
+          ...(normalizedRelTokens.includes("noopener") ? [] : ["noopener"]),
+          ...(normalizedRelTokens.includes("noreferrer") ? [] : ["noreferrer"]),
+        ].join(" ")
+      : rel;
+  if (target !== undefined) {
+    return (
+      <a
+        {...anchorProps}
+        href={href}
+        target={target}
+        rel={resolvedRel}
+        onClick={handleClick}
+      />
+    );
+  }
   return (
     <RouteAnchor
       {...anchorProps}
       href={href}
-      target={target}
-      rel={target === "_blank" ? (rel ?? "noopener noreferrer") : rel}
+      rel={resolvedRel}
       onClick={handleClick}
     />
   );

apps/app/src/lib/live-file-navigation.test.ts

@@ -56,6 +56,30 @@ describe("normalizeExperimentalLiveFileTarget", () => {
   ])("rejects ambiguous or non-exact target %#", (target) => {
     expect(normalizeExperimentalLiveFileTarget(target)).toBeNull();
   });
+
+  it("accepts valid surrogate pairs and rejects unpaired surrogates", () => {
+    expect(
+      normalizeExperimentalLiveFileTarget({
+        kind: "workspace",
+        environmentId: "env_1",
+        path: `reports/${String.fromCodePoint(0x1f4c4)}.md`,
+      }),
+    ).not.toBeNull();
+
+    for (const path of [
+      String.fromCharCode(0xd800),
+      String.fromCharCode(0xdc00),
+      `a${String.fromCharCode(0xd800)}b`,
+    ]) {
+      expect(
+        normalizeExperimentalLiveFileTarget({
+          kind: "workspace",
+          environmentId: "env_1",
+          path,
+        }),
+      ).toBeNull();
+    }
+  });
 });
 
 describe("normalizeExperimentalFileOpenOptions", () => {