diff --git a/bootstrap/src/procmgr.rs b/bootstrap/src/procmgr.rs
index acff0940f0..a1cd24275c 100644
--- a/bootstrap/src/procmgr.rs
+++ b/bootstrap/src/procmgr.rs
@@ -542,6 +542,20 @@ enum Handle {
     SchemeRoot,
 }
 
+// Red Bear diagnostic (2026-07-15): name a Handle variant for the boot-crash
+// trace. randd's thr_fd resolves to procmgr (scheme 18) handle #8, which
+// on_dup rejects with EBADF; this shows what kind #8 actually is.
+fn handle_kind_str(h: &Handle) -> &'static str {
+    match h {
+        Handle::Init => "Init",
+        Handle::Proc(_) => "Proc",
+        Handle::Thread(_) => "Thread",
+        Handle::Ps(_) => "Ps",
+        Handle::ProcCredsCapability => "ProcCredsCapability",
+        Handle::SchemeRoot => "SchemeRoot",
+    }
+}
+
 #[derive(Clone, Copy, Debug)]
 enum WaitpidTarget {
     SingleProc(ProcessId),
@@ -876,20 +890,45 @@ impl<'a> ProcScheme<'a> {
     }
     fn on_dup(&mut self, old_id: usize, buf: &[u8]) -> Result<OpenResult> {
         log::trace!("Dup request");
+        {
+            let kind = self.handles.get(old_id).map(handle_kind_str);
+            let _ = syscall::write(
+                1,
+                alloc::format!(
+                    "PROCMGR on_dup id={} kind={:?} buf={:?}\n",
+                    old_id,
+                    kind,
+                    core::str::from_utf8(buf).unwrap_or("<bin>")
+                )
+                .as_bytes(),
+            );
+        }
         match self.handles[old_id] {
             Handle::Proc(pid) => match buf {
                 b"fork" => {
                     log::trace!("Forking {pid:?}");
                     let child_pid = self.fork(pid)?;
+                    let number = self.handles.insert(Handle::Proc(child_pid));
+                    let _ = syscall::write(
+                        1,
+                        alloc::format!("PROCMGR fork pid={:?} -> Proc handle={}\n", child_pid, number)
+                            .as_bytes(),
+                    );
                     Ok(OpenResult::ThisScheme {
-                        number: self.handles.insert(Handle::Proc(child_pid)),
+                        number,
                         flags: NewFdFlags::empty(),
                     })
                 }
                 b"new-thread" => {
                     let thread = self.new_thread(pid)?;
+                    let number = self.handles.insert(Handle::Thread(Rc::downgrade(&thread)));
+                    let _ = syscall::write(
+                        1,
+                        alloc::format!("PROCMGR new-thread pid={:?} -> Thread handle={}\n", pid, number)
+                            .as_bytes(),
+                    );
                     Ok(OpenResult::ThisScheme {
-                        number: self.handles.insert(Handle::Thread(Rc::downgrade(&thread))),
+                        number,
                         flags: NewFdFlags::empty(),
                     })
                 }
@@ -900,9 +939,18 @@ impl<'a> ProcScheme<'a> {
                         .ok_or(Error::new(EINVAL))?;
                     let process = self.processes.get(&pid).ok_or(Error::new(EBADFD))?.borrow();
                     let thread = Rc::downgrade(process.threads.get(idx).ok_or(Error::new(ENOENT))?);
+                    let number = self.handles.insert(Handle::Thread(thread));
+                    let _ = syscall::write(
+                        1,
+                        alloc::format!(
+                            "PROCMGR thread-{} pid={:?} -> Thread handle={}\n",
+                            idx, pid, number
+                        )
+                        .as_bytes(),
+                    );
 
                     return Ok(OpenResult::ThisScheme {
-                        number: self.handles.insert(Handle::Thread(thread)),
+                        number,
                         flags: NewFdFlags::empty(),
                     });
                 }
@@ -2469,6 +2517,11 @@ impl<'a> ProcScheme<'a> {
         Ok(())
     }
     fn on_close(&mut self, id: usize) {
+        let kind = self.handles.get(id).map(handle_kind_str);
+        let _ = syscall::write(
+            1,
+            alloc::format!("PROCMGR on_close id={} kind={:?}\n", id, kind).as_bytes(),
+        );
         if self.handles.try_remove(id).is_none() {
             log::error!("on_close for nonexistent handle, id={id}");
         }