diag(kernel): log userspace scheme id + registrant pid

src/scheme/mod.rs

@@ -233,6 +233,11 @@ impl SchemeList {
 
     /// Create a new scheme.
     fn insert(&self, context: Weak<ContextLock>, token: &mut CleanLockToken) -> Result<SchemeId> {
+        // Red Bear diagnostic (2026-07-15): capture the registrant pid before
+        // taking the handles lock, to correlate userspace scheme ids (e.g. the
+        // scheme=18 that randd's thr_fd resolves to in the boot crash) with the
+        // daemon that registered them.
+        let registrant_pid = context.upgrade().map(|c| c.read(token.token()).pid);
         let mut handles = handles().write(token.token());
         let id = loop {
             let mut id = SCHEME_LIST_NEXT_ID.fetch_add(1, Ordering::Relaxed);
@@ -249,6 +254,12 @@ impl SchemeList {
             }
         };
 
+        error!(
+            "scheme.insert: scheme_id={} registrant_pid={:?}",
+            id.get(),
+            registrant_pid
+        );
+
         let root_id = SchemeId(SCHEME_LIST_ID.load(Ordering::Relaxed));
         let inner = Arc::new(UserInner::new(root_id, id, context));
         let new_scheme = Handle::Scheme(KernelSchemes::User(UserScheme::new(inner)));