fix(server): refuse editor paths with line breaks or quotes when the editor is a Windows command shim

apps/server/src/process/externalLauncher.test.ts

@@ -7,7 +7,9 @@ import * as NodeServices from "@effect/platform-node/NodeServices";
 import { assert, it } from "@effect/vitest";
 import * as ConfigProvider from "effect/ConfigProvider";
 import * as Deferred from "effect/Deferred";
+import * as Cause from "effect/Cause";
 import * as Effect from "effect/Effect";
+import * as Exit from "effect/Exit";
 import * as Fiber from "effect/Fiber";
 import * as FileSystem from "effect/FileSystem";
 import * as Layer from "effect/Layer";
@@ -1381,6 +1383,93 @@ it.effect("keeps scanning after the caller is interrupted and shares that scan",
   );
 });
 
+const launchWindowsShimEditor = (cwd: string) =>
+  Effect.gen(function* () {
+    const fileSystem = yield* FileSystem.FileSystem;
+    const path = yield* Path.Path;
+    const binDir = yield* fileSystem.makeTempDirectoryScoped({ prefix: "t3-editors-" });
+    yield* fileSystem.writeFileString(path.join(binDir, "code.CMD"), "@echo off\r\n");
+    let spawned: ChildProcess.StandardCommand | undefined;
+    const exit = yield* Effect.gen(function* () {
+      const launcher = yield* ExternalLauncher.ExternalLauncher;
+      return yield* launcher.launchEditor({ editor: "vscode", cwd }).pipe(Effect.exit);
+    }).pipe(
+      Effect.provide(
+        layerTest({
+          platform: "win32",
+          env: { PATH: binDir, PATHEXT: ".COM;.EXE;.BAT;.CMD" },
+          resolveExecutable: (command) =>
+            command === "code" ? "C:\\Program Files\\Microsoft VS Code\\bin\\code.CMD" : command,
+          onSpawn: (command) => {
+            spawned = command;
+          },
+        }),
+      ),
+    );
+    return { exit, spawned };
+  }).pipe(Effect.scoped, Effect.provide(NodeServices.layer));
+
+it.effect.each([
+  ["CRLF", "C:\\workspace\\file.ts\r\ncalc.exe"],
+  ["LF", "C:\\workspace\\file.ts\ncalc.exe"],
+  ["double quote", 'C:\\workspace\\file.ts" & calc.exe & "'],
+] as const)("does not start a Windows command shim for a path with a $0", ([, cwd]) =>
+  Effect.gen(function* () {
+    const { exit, spawned } = yield* launchWindowsShimEditor(cwd);
+    assert.equal(spawned, undefined);
+    assert.isTrue(Exit.isFailure(exit));
+    if (Exit.isFailure(exit)) {
+      assert.instanceOf(
+        Cause.squash(exit.cause),
+        ExternalLauncher.ExternalLauncherEditorSpawnError,
+      );
+    }
+  }),
+);
+
+it.effect("starts a Windows command shim for unicode paths with cmd metacharacters", () =>
+  Effect.gen(function* () {
+    const { exit, spawned } = yield* launchWindowsShimEditor(
+      "C:\\Users\\jö\\R&D (100%)\\naïve ^file!.ts:3:7",
+    );
+    assert.isTrue(Exit.isSuccess(exit));
+    assert.ok(spawned);
+    assert.equal(spawned.options.shell, true);
+    assert.deepEqual(spawned.args, [
+      '^"--goto^"',
+      '^"C:\\Users\\jö\\R^&D^ ^(100^%^)\\naïve^ ^^file^!.ts:3:7^"',
+    ]);
+  }),
+);
+
+it.effect.skipIf(windowsHost)("passes line breaks through to editors started without a shell", () =>
+  Effect.gen(function* () {
+    const fileSystem = yield* FileSystem.FileSystem;
+    const path = yield* Path.Path;
+    const binDir = yield* fileSystem.makeTempDirectoryScoped({ prefix: "t3-editors-" });
+    const zed = path.join(binDir, "zed");
+    yield* fileSystem.writeFileString(zed, "#!/bin/sh\n");
+    yield* fileSystem.chmod(zed, 0o755);
+    let spawned: ChildProcess.StandardCommand | undefined;
+    yield* Effect.gen(function* () {
+      const launcher = yield* ExternalLauncher.ExternalLauncher;
+      yield* launcher.launchEditor({ editor: "zed", cwd: "/workspace/odd\nname.ts" });
+    }).pipe(
+      Effect.provide(
+        layerTest({
+          platform: "linux",
+          env: { PATH: binDir, HOME: binDir },
+          onSpawn: (command) => {
+            spawned = command;
+          },
+        }),
+      ),
+    );
+    assert.ok(spawned);
+    assert.deepEqual(spawned.args, ["/workspace/odd\nname.ts"]);
+  }).pipe(Effect.scoped, Effect.provide(NodeServices.layer)),
+);
+
 it.effect("rejects unknown editors through the service API", () =>
   Effect.gen(function* () {
     const launcher = yield* ExternalLauncher.ExternalLauncher;

apps/server/src/process/externalLauncher.ts

@@ -74,6 +74,14 @@ interface TargetPathAndPosition {
   readonly column: Option.Option<string>;
 }
 
+/**
+ * Windows command shims (`code.cmd`) forward arguments through `%*`, which
+ * cmd.exe parses a second time after the first escaping layer is gone: a
+ * line break ends the command there, and a double quote closes the quoting
+ * that keeps `&` or `|` literal. Neither can occur in a Windows path.
+ */
+// oxlint-disable-next-line no-control-regex
+const WINDOWS_SHIM_UNSAFE_ARG_PATTERN = /[\u0000-\u001f\u007f"]/;
 const TARGET_WITH_POSITION_PATTERN = /^(.*?):(\d+)(?::(\d+))?$/;
 const POWERSHELL_ARGUMENTS_PREFIX = [
   "-NoProfile",
@@ -726,6 +734,15 @@ const launchEditorProcess = Effect.fn("externalLauncher.launchEditorProcess")(fu
   }
 
   const spawnCommand = yield* resolveSpawnCommand(launch.command, launch.args, { env });
+  if (spawnCommand.shell && launch.args.some((arg) => WINDOWS_SHIM_UNSAFE_ARG_PATTERN.test(arg))) {
+    return yield* new ExternalLauncherEditorSpawnError({
+      editor: launch.editor,
+      target: launch.target,
+      command: launch.command,
+      args: launch.args,
+      cause: new Error("Editor arguments contain characters a Windows command shim cannot pass"),
+    });
+  }
   yield* launchAndUnref(
     {
       command: spawnCommand.command,