diff --git a/lang/src/compiler/entry/compiler_stageb.hako b/lang/src/compiler/entry/compiler_stageb.hako
index b0b2eb8b..5613eeb1 100644
--- a/lang/src/compiler/entry/compiler_stageb.hako
+++ b/lang/src/compiler/entry/compiler_stageb.hako
@@ -48,6 +48,19 @@ static box StageBArgsBox {
 // Phase 25.1c: Body extraction + bundle + using + trim
 static box StageBBodyExtractorBox {
   build_body_src(src, args) {
+    // ============================================================================
+    // Depth guard: prevent accidental recursion inside Stage‑B body extractor
+    // ============================================================================
+    {
+      local depth = env.get("HAKO_STAGEB_BODY_DEPTH")
+      if depth != null && ("" + depth) != "0" {
+        print("[stageb/recursion] StageBBodyExtractorBox.build_body_src recursion detected")
+        // Fail-fast but still return a sensible value: fall back to original src
+        return src
+      }
+      env.set("HAKO_STAGEB_BODY_DEPTH", "1")
+    }
+
     // ============================================================================
     // 4) Body extraction: extract main method body from box Main wrapper
     // ============================================================================
@@ -594,6 +607,8 @@ static box StageBBodyExtractorBox {
       if e > b { body_src = s.substring(b, e) } else { body_src = "" }
     }
 
+    // Clear depth guard before returning
+    env.set("HAKO_STAGEB_BODY_DEPTH", "0")
     return body_src
   }
 }
@@ -601,6 +616,18 @@ static box StageBBodyExtractorBox {
 // Phase 25.1c: Main driver logic
 static box StageBDriverBox {
   main(args) {
+    // ============================================================================
+    // Depth guard: prevent accidental recursion in Stage‑B driver entry
+    // ============================================================================
+    {
+      local depth = env.get("HAKO_STAGEB_DRIVER_DEPTH")
+      if depth != null && ("" + depth) != "0" {
+        print("[stageb/recursion] StageBDriverBox.main recursion detected")
+        return -1
+      }
+      env.set("HAKO_STAGEB_DRIVER_DEPTH", "1")
+    }
+
     local src = StageBArgsBox.resolve_src(args)
 
     // 2) Stage‑3 acceptance default ON for selfhost (env may turn off; keep tolerant here)
@@ -685,6 +712,8 @@ static box StageBDriverBox {
     }
 
     print(ast_json)
+    // Clear depth guard before returning
+    env.set("HAKO_STAGEB_DRIVER_DEPTH", "0")
     return 0
   }
 }