diff --git a/lang/src/compiler/entry/bundle_resolver.hako b/lang/src/compiler/entry/bundle_resolver.hako
index 72c08249..90f29a7d 100644
--- a/lang/src/compiler/entry/bundle_resolver.hako
+++ b/lang/src/compiler/entry/bundle_resolver.hako
@@ -7,6 +7,15 @@ static box BundleResolver {
   //  - --require-mod Name must appear in named bundles ([bundle/missing] Name)
   //  - Merge order: bundle-src* → bundle-mod* (in given order)
   resolve(bundle_srcs, bundle_names, bundle_mod_srcs, require_mods) {
+    // Shallow recursion guard to prevent accidental self-recursion in Stage‑B bundler.
+    {
+      local depth = env.get("HAKO_STAGEB_BUNDLE_DEPTH")
+      if depth != null && ("" + depth) != "0" {
+        print("[stageb/recursion] BundleResolver.resolve recursion detected")
+        return null
+      }
+      env.set("HAKO_STAGEB_BUNDLE_DEPTH", "1")
+    }
     // Alias table via env: HAKO_BUNDLE_ALIAS_TABLE / NYASH_BUNDLE_ALIAS_TABLE
     // Format: entries separated by '|||', each entry as 'Name:code'
     local table = env.get("HAKO_BUNDLE_ALIAS_TABLE")
@@ -101,6 +110,8 @@ static box BundleResolver {
       local i2 = 0; local m2 = bundle_mod_srcs.length()
       loop(i2 < m2) { merged = merged + bundle_mod_srcs.get(i2) + "\n" i2 = i2 + 1 }
     }
+    // Clear depth guard before returning
+    env.set("HAKO_STAGEB_BUNDLE_DEPTH", "0")
     return merged
   }
 }
diff --git a/lang/src/compiler/entry/using_resolver_box.hako b/lang/src/compiler/entry/using_resolver_box.hako
index 0eee4a4b..003bdeee 100644
--- a/lang/src/compiler/entry/using_resolver_box.hako
+++ b/lang/src/compiler/entry/using_resolver_box.hako
@@ -14,6 +14,16 @@ using selfhost.shared.json.utils.json_frag as JsonFragBox
 
 static box Stage1UsingResolverBox {
   resolve_for_source(src) {
+    // Shallow recursion guard to prevent accidental self-recursion in Stage‑1 using resolver.
+    {
+      local depth = env.get("HAKO_STAGEB_USING_DEPTH")
+      if depth != null && ("" + depth) != "0" {
+        print("[stageb/recursion] Stage1UsingResolverBox.resolve_for_source recursion detected")
+        return ""
+      }
+      env.set("HAKO_STAGEB_USING_DEPTH", "1")
+    }
+
     if src == null { return "" }
     local apply_flag = env.get("HAKO_STAGEB_APPLY_USINGS")
     if apply_flag != null && ("" + apply_flag) == "0" { return "" }
@@ -52,6 +62,8 @@ static box Stage1UsingResolverBox {
       i = i + 1
     }
 
+    // Clear depth guard before returning
+    env.set("HAKO_STAGEB_USING_DEPTH", "0")
     return prefix
   }