feat(core): add embedded v2 session runtime and tool foundation (#30632)

packages/core/src/fs-util.ts

@@ -1,5 +1,5 @@
 import { NodeFileSystem } from "@effect/platform-node"
-import { dirname, join, relative, resolve as pathResolve } from "path"
+import { dirname, isAbsolute, join, relative, resolve as pathResolve, sep } from "path"
 import { realpathSync } from "fs"
 import * as NFS from "fs/promises"
 import { lookup } from "mime-types"
@@ -236,12 +236,11 @@ export namespace FSUtil {
   }
 
   export function overlaps(a: string, b: string) {
-    const relA = relative(a, b)
-    const relB = relative(b, a)
-    return !relA || !relA.startsWith("..") || !relB || !relB.startsWith("..")
+    return contains(a, b) || contains(b, a)
   }
 
   export function contains(parent: string, child: string) {
-    return !relative(parent, child).startsWith("..")
+    const result = relative(parent, child)
+    return result === "" || (!isAbsolute(result) && result !== ".." && !result.startsWith(`..${sep}`))
   }
 }