merge: combine 0a358aa0 (diag + libc::pipe2 fix) with 104da7de (init FILETABLE fix) into canonical submodule/base

Both branches independently fixed the FILETABLE desync bug. This merge creates a single canonical history that preserves the diagnostic commits from 0a358aa0 and the eexist-focused fix from 104da7de.

After this merge, the per-fork submodule/<name> branch (this is the AGENTS.md-mandated canonical ref) is a child of both, so origin can fast-forward to it.

(NO AI attribution in commit message body, per project policy)

init/src/service.rs

@@ -38,8 +38,15 @@ pub enum ServiceType {
 
 fn create_pipe() -> io::Result<(File, OwnedFd)> {
     let mut fds = [0i32; 2];
-    let res = unsafe { libc::pipe2(fds.as_mut_ptr(), libc::O_CLOEXEC) };
-    if res != 0 {
+    // Use libc::pipe2() which goes through relibc's FILETABLE-managed path
+    // (FdGuard::open → SYS_OPENAT_INTO), keeping the userspace file table in
+    // sync with the kernel's file table. Using raw syscall::openat()
+    // (SYS_OPENAT) here would bypass the FILETABLE and create phantom fds
+    // that later cause EEXIST collisions when relibc's own pipe2() (called
+    // during Command::spawn fork+exec) tries to insert at a position the
+    // FILETABLE incorrectly thinks is free.
+    let ret = unsafe { libc::pipe2(fds.as_mut_ptr(), libc::O_CLOEXEC) };
+    if ret != 0 {
         return Err(io::Error::last_os_error());
     }
     let rd = unsafe { File::from_raw_fd(fds[0]) };