diff --git a/src/mir/builder/builder_calls.rs b/src/mir/builder/builder_calls.rs
index 8690cde8..4663abd4 100644
--- a/src/mir/builder/builder_calls.rs
+++ b/src/mir/builder/builder_calls.rs
@@ -13,75 +13,7 @@ impl super::MirBuilder {
     /// Annotate a call result `dst` with the return type and origin if the callee
     /// is a known user/static function in the current module.
     pub(super) fn annotate_call_result_from_func_name<S: AsRef<str>>(&mut self, dst: super::ValueId, func_name: S) {
-        let name = func_name.as_ref();
-        // 1) Prefer module signature when available
-        if let Some(ref module) = self.current_module {
-            if let Some(func) = module.functions.get(name) {
-                let mut ret = func.signature.return_type.clone();
-                // Targeted stabilization: JsonParser.parse/1 should produce JsonNode
-                // If signature is Unknown/Void, normalize to Box("JsonNode")
-                if name == "JsonParser.parse/1" {
-                    if matches!(ret, super::MirType::Unknown | super::MirType::Void) {
-                        ret = super::MirType::Box("JsonNode".into());
-                    }
-                }
-                // Token path: JsonParser.current_token/0 should produce JsonToken
-                if name == "JsonParser.current_token/0" {
-                    if matches!(ret, super::MirType::Unknown | super::MirType::Void) {
-                        ret = super::MirType::Box("JsonToken".into());
-                    }
-                }
-                // Parser factory: JsonParserModule.create_parser/0 returns JsonParser
-                if name == "JsonParserModule.create_parser/0" {
-                    // Normalize to Known Box(JsonParser)
-                    ret = super::MirType::Box("JsonParser".into());
-                }
-                self.value_types.insert(dst, ret.clone());
-                if let super::MirType::Box(bx) = ret {
-                    self.value_origin_newbox.insert(dst, bx);
-                    if super::utils::builder_debug_enabled() || std::env::var("NYASH_BUILDER_DEBUG").ok().as_deref() == Some("1") {
-                        let bx = self.value_origin_newbox.get(&dst).cloned().unwrap_or_default();
-                        super::utils::builder_debug_log(&format!("annotate call dst={} from {} -> Box({})", dst.0, name, bx));
-                    }
-                }
-                return;
-            }
-        }
-        // 2) No module signature—apply minimal heuristic for known functions
-        if name == "JsonParser.parse/1" {
-            let ret = super::MirType::Box("JsonNode".into());
-            self.value_types.insert(dst, ret.clone());
-            if let super::MirType::Box(bx) = ret { self.value_origin_newbox.insert(dst, bx); }
-            if super::utils::builder_debug_enabled() || std::env::var("NYASH_BUILDER_DEBUG").ok().as_deref() == Some("1") {
-                super::utils::builder_debug_log(&format!("annotate call (fallback) dst={} from {} -> Box(JsonNode)", dst.0, name));
-            }
-        } else if name == "JsonParser.current_token/0" {
-            let ret = super::MirType::Box("JsonToken".into());
-            self.value_types.insert(dst, ret.clone());
-            if let super::MirType::Box(bx) = ret { self.value_origin_newbox.insert(dst, bx); }
-            if super::utils::builder_debug_enabled() || std::env::var("NYASH_BUILDER_DEBUG").ok().as_deref() == Some("1") {
-                super::utils::builder_debug_log(&format!("annotate call (fallback) dst={} from {} -> Box(JsonToken)", dst.0, name));
-            }
-        } else if name == "JsonTokenizer.tokenize/0" {
-            // Tokenize returns an ArrayBox of tokens
-            let ret = super::MirType::Box("ArrayBox".into());
-            self.value_types.insert(dst, ret.clone());
-            if let super::MirType::Box(bx) = ret { self.value_origin_newbox.insert(dst, bx); }
-            if super::utils::builder_debug_enabled() || std::env::var("NYASH_BUILDER_DEBUG").ok().as_deref() == Some("1") {
-                super::utils::builder_debug_log(&format!("annotate call (fallback) dst={} from {} -> Box(ArrayBox)", dst.0, name));
-            }
-        } else if name == "JsonParserModule.create_parser/0" {
-            // Fallback path for parser factory
-            let ret = super::MirType::Box("JsonParser".into());
-            self.value_types.insert(dst, ret.clone());
-            if let super::MirType::Box(bx) = ret { self.value_origin_newbox.insert(dst, bx); }
-            if super::utils::builder_debug_enabled() || std::env::var("NYASH_BUILDER_DEBUG").ok().as_deref() == Some("1") {
-                super::utils::builder_debug_log(&format!("annotate call (fallback) dst={} from {} -> Box(JsonParser)", dst.0, name));
-            }
-        } else {
-            // Generic tiny whitelist for known primitive-like utilities (spec unchanged)
-            crate::mir::builder::types::annotation::annotate_from_function(self, dst, name);
-        }
+        super::calls::annotation::annotate_call_result_from_func_name(self, dst, func_name)
     }
     /// Unified call emission - replaces all emit_*_call methods
     /// ChatGPT5 Pro A++ design for complete call unification
diff --git a/src/mir/builder/calls/annotation.rs b/src/mir/builder/calls/annotation.rs
new file mode 100644
index 00000000..b595a40e
--- /dev/null
+++ b/src/mir/builder/calls/annotation.rs
@@ -0,0 +1,82 @@
+// Call result annotation helpers
+// Extracted from builder_calls.rs to keep files lean
+
+use super::super::{MirBuilder, MirType, ValueId};
+
+/// Annotate a call result `dst` with the return type and origin if the callee
+/// is a known user/static function in the current module.
+pub(in super::super) fn annotate_call_result_from_func_name<S: AsRef<str>>(
+    builder: &mut MirBuilder,
+    dst: ValueId,
+    func_name: S,
+) {
+    let name = func_name.as_ref();
+    // 1) Prefer module signature when available
+    if let Some(ref module) = builder.current_module {
+        if let Some(func) = module.functions.get(name) {
+            let mut ret = func.signature.return_type.clone();
+            // Targeted stabilization: JsonParser.parse/1 should produce JsonNode
+            // If signature is Unknown/Void, normalize to Box("JsonNode")
+            if name == "JsonParser.parse/1" {
+                if matches!(ret, MirType::Unknown | MirType::Void) {
+                    ret = MirType::Box("JsonNode".into());
+                }
+            }
+            // Token path: JsonParser.current_token/0 should produce JsonToken
+            if name == "JsonParser.current_token/0" {
+                if matches!(ret, MirType::Unknown | MirType::Void) {
+                    ret = MirType::Box("JsonToken".into());
+                }
+            }
+            // Parser factory: JsonParserModule.create_parser/0 returns JsonParser
+            if name == "JsonParserModule.create_parser/0" {
+                // Normalize to Known Box(JsonParser)
+                ret = MirType::Box("JsonParser".into());
+            }
+            builder.value_types.insert(dst, ret.clone());
+            if let MirType::Box(bx) = ret {
+                builder.value_origin_newbox.insert(dst, bx);
+                if super::super::utils::builder_debug_enabled() || std::env::var("NYASH_BUILDER_DEBUG").ok().as_deref() == Some("1") {
+                    let bx = builder.value_origin_newbox.get(&dst).cloned().unwrap_or_default();
+                    super::super::utils::builder_debug_log(&format!("annotate call dst={} from {} -> Box({})", dst.0, name, bx));
+                }
+            }
+            return;
+        }
+    }
+    // 2) No module signature—apply minimal heuristic for known functions
+    if name == "JsonParser.parse/1" {
+        let ret = MirType::Box("JsonNode".into());
+        builder.value_types.insert(dst, ret.clone());
+        if let MirType::Box(bx) = ret { builder.value_origin_newbox.insert(dst, bx); }
+        if super::super::utils::builder_debug_enabled() || std::env::var("NYASH_BUILDER_DEBUG").ok().as_deref() == Some("1") {
+            super::super::utils::builder_debug_log(&format!("annotate call (fallback) dst={} from {} -> Box(JsonNode)", dst.0, name));
+        }
+    } else if name == "JsonParser.current_token/0" {
+        let ret = MirType::Box("JsonToken".into());
+        builder.value_types.insert(dst, ret.clone());
+        if let MirType::Box(bx) = ret { builder.value_origin_newbox.insert(dst, bx); }
+        if super::super::utils::builder_debug_enabled() || std::env::var("NYASH_BUILDER_DEBUG").ok().as_deref() == Some("1") {
+            super::super::utils::builder_debug_log(&format!("annotate call (fallback) dst={} from {} -> Box(JsonToken)", dst.0, name));
+        }
+    } else if name == "JsonTokenizer.tokenize/0" {
+        // Tokenize returns an ArrayBox of tokens
+        let ret = MirType::Box("ArrayBox".into());
+        builder.value_types.insert(dst, ret.clone());
+        if let MirType::Box(bx) = ret { builder.value_origin_newbox.insert(dst, bx); }
+        if super::super::utils::builder_debug_enabled() || std::env::var("NYASH_BUILDER_DEBUG").ok().as_deref() == Some("1") {
+            super::super::utils::builder_debug_log(&format!("annotate call (fallback) dst={} from {} -> Box(ArrayBox)", dst.0, name));
+        }
+    } else if name == "JsonParserModule.create_parser/0" {
+        // Fallback path for parser factory
+        let ret = MirType::Box("JsonParser".into());
+        builder.value_types.insert(dst, ret.clone());
+        if let MirType::Box(bx) = ret { builder.value_origin_newbox.insert(dst, bx); }
+        if super::super::utils::builder_debug_enabled() || std::env::var("NYASH_BUILDER_DEBUG").ok().as_deref() == Some("1") {
+            super::super::utils::builder_debug_log(&format!("annotate call (fallback) dst={} from {} -> Box(JsonParser)", dst.0, name));
+        }
+    } else {
+        // Generic tiny whitelist for known primitive-like utilities (spec unchanged)
+        crate::mir::builder::types::annotation::annotate_from_function(builder, dst, name);
+    }
+}
diff --git a/src/mir/builder/calls/mod.rs b/src/mir/builder/calls/mod.rs
index 4c63111a..5c4b1be7 100644
--- a/src/mir/builder/calls/mod.rs
+++ b/src/mir/builder/calls/mod.rs
@@ -24,6 +24,9 @@ pub mod function_lowering;
 // Unified call system
 pub mod call_unified;
 
+// Call result annotation
+pub mod annotation;
+
 // Re-export commonly used items
 pub use method_resolution::{
     resolve_call_target,