diff --git a/CURRENT_TASK.md b/CURRENT_TASK.md
index 7b59da1d..69bb0ab8 100644
--- a/CURRENT_TASK.md
+++ b/CURRENT_TASK.md
@@ -357,14 +357,25 @@
 38. **Follow-up（コミット済み✅ `0aad016b` 2025-12-13）**: legacy promoted lookup の deprecation warning を局所化
 	   - `ScopeManager::lookup` 内の legacy 呼び出しを `#[allow(deprecated)]` で包み、全ビルドでの警告を抑制
 
+39. **Phase 78-A（コミット済み✅ `10e78fa3` 2025-12-13）**: PromotedBindingRecorder の整理（dev-only）
+   - binding_map の受け渡しを Box 化し、検出器（Detector）と記録（Recorder）の責務を分離。
+   - 以後の “BindingId を供給する導線” の議論を単純化するための整地。
+
+40. **Phase 79（コミット済み✅ `48bdf2fb` 2025-12-13）**: Detector/Recorder separation + BindingMapProvider
+   - `BindingMapProvider` を導入し、`#[cfg(feature="normalized_dev")]` の散在を抑制する方向へ。
+
 ---
 
 ## 🚀 次フェーズ候補（Phase 78+）
 
-### Phase 78（dev-only）: BindingId Migration を “完結” に寄せる
-- Pattern3/4 で binding_id を供給する導線を追加し、name fallback を観測可能に縮退
-- Phase 77 で先送りした E2E tests 4本を追加（DigitPos/Trim/P3/P4）
-- 余裕があれば: legacy name-based promoted lookup の撤去計画を docs に明記（削除は Phase 79 でも可）
+### Phase 78-B（dev-only）: “promoted carriers” を BindingId で接続する（進行中）
+- SSOT: `docs/development/current/main/phase78-bindingid-promoted-carriers.md`
+- 目的: `BindingId(original)` → `BindingId(promoted)` → `ValueId(join)` の鎖を作り、name-hack 依存を減らす。
+- 残タスク（優先順）:
+  1) ExprLowerer/ConditionLoweringBox の call-site で `lookup_with_binding()` を実際に使う（BindingId が効く状態にする）
+  2) Trim/Pattern4 側の “BindingId → join” を E2E で固定（DigitPos 以外の回帰ガード）
+  3) Pattern3/4 の本番導線へ拡張（P3 if-sum / P4 continue の binding 供給）
+  4) legacy name-based promoted lookup の縮退 → 撤去計画を docs に固定（削除自体は Phase 80+ でも可）
 
 ---
 
diff --git a/docs/development/current/main/phase78-bindingid-promoted-carriers.md b/docs/development/current/main/phase78-bindingid-promoted-carriers.md
new file mode 100644
index 00000000..b8b94f1f
--- /dev/null
+++ b/docs/development/current/main/phase78-bindingid-promoted-carriers.md
@@ -0,0 +1,61 @@
+## Phase 78: BindingId for Promoted Carriers (dev-only)
+
+### Goal
+
+Make LoopBodyLocal promotion (DigitPos/Trim) **BindingId-aware** without relying on fragile name-based hacks like `format!("is_{}", name)`.
+
+This phase introduces a dev-only identity link:
+
+- `BindingId(original LoopBodyLocal)` → `BindingId(promoted carrier)` → `ValueId(join carrier param)`
+
+### Problem
+
+Promotion creates synthetic carrier names (例: `is_digit_pos`, `is_ch_match`) that do not exist as source-level bindings.
+
+- `PromotedBindingRecorder` expects both original/promoted names in `MirBuilder.binding_map`.
+- For promoted carriers this is not true by construction.
+- For LoopBodyLocal variables, promotion can happen before their `local` is lowered, so the original name may also be absent.
+
+### Solution (current state)
+
+#### 1) CarrierVar gets optional BindingId (dev-only)
+
+- `src/mir/join_ir/lowering/carrier_info.rs`
+  - `CarrierVar.binding_id: Option<BindingId>` (feature `normalized_dev`)
+
+#### 2) CarrierBindingAssigner box
+
+- `src/mir/join_ir/lowering/carrier_binding_assigner.rs`
+  - Ensures both sides have BindingIds:
+    - If `original_name` is missing in `builder.binding_map`, allocate a temporary BindingId.
+    - If `promoted_carrier_name` is missing, allocate a temporary BindingId.
+  - Records:
+    - `carrier_info.promoted_bindings[original_bid] = promoted_bid`
+    - `CarrierVar.binding_id = Some(promoted_bid)` for the promoted carrier
+  - Restores `builder.binding_map` after recording (synthetic names do not leak into the source map).
+
+#### 3) Pattern2/Pattern4 wiring
+
+- Pattern2 (break): `src/mir/builder/control_flow/joinir/patterns/pattern2_with_break.rs`
+  - Calls `CarrierBindingAssigner::assign_promoted_binding()` immediately after promotion.
+  - Registers `BindingId → ValueId` via `ConditionEnv.register_carrier_binding()` after carrier join_id allocation.
+  - Keeps legacy name-based aliasing (`digit_pos` → `is_digit_pos`) for now, but removes local “guess naming” by using the promoted carrier name returned by the promoter.
+
+- Pattern4 (continue): `src/mir/builder/control_flow/joinir/patterns/pattern4_with_continue.rs`
+  - Calls `CarrierBindingAssigner::assign_promoted_binding()` after promotion (analysis metadata only, since Pattern4’s current lowering path does not use JoinValueSpace params).
+
+### Tests
+
+- Unit test (dev-only): `src/mir/builder/control_flow/joinir/patterns/pattern2_with_break.rs`
+  - `phase78_promoted_binding_is_recorded_for_digitpos`
+  - Asserts:
+    - `promoted_bindings` has one mapping
+    - promoted carrier has `binding_id`
+    - `ConditionEnv.binding_id_map[promoted_bid] == promoted_carrier.join_id`
+
+### Open Follow-ups (Phase 79+)
+
+1. Wire `ScopeManager::lookup_with_binding()` into ExprLowerer/ConditionLoweringBox call-sites (so BindingId actually drives resolution).
+2. Extend coverage to Trim and other promotion shapes (additional unit/E2E tests).
+3. Shrink/remove legacy name-based promoted lookup (`resolve_promoted_join_id`) after call-sites consistently provide BindingId.
+
diff --git a/src/mir/builder/control_flow/joinir/patterns/common_init.rs b/src/mir/builder/control_flow/joinir/patterns/common_init.rs
index f86283c7..654978ea 100644
--- a/src/mir/builder/control_flow/joinir/patterns/common_init.rs
+++ b/src/mir/builder/control_flow/joinir/patterns/common_init.rs
@@ -164,6 +164,8 @@ impl CommonPatternInitializer {
                             join_id: None,
                             role: crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState, // Phase 227: Default
                             init: crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost, // Phase 228: Default
+                            #[cfg(feature = "normalized_dev")]
+                            binding_id: None,
                         })
                         } else {
                             None
diff --git a/src/mir/builder/control_flow/joinir/patterns/exit_binding.rs b/src/mir/builder/control_flow/joinir/patterns/exit_binding.rs
index 2f3e1de9..17947d0e 100644
--- a/src/mir/builder/control_flow/joinir/patterns/exit_binding.rs
+++ b/src/mir/builder/control_flow/joinir/patterns/exit_binding.rs
@@ -144,6 +144,8 @@ mod tests {
                 join_id: None,
                 role: crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState,
                 init: crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost, // Phase 228
+                #[cfg(feature = "normalized_dev")]
+                binding_id: None,
             }],
         );
 
@@ -187,6 +189,8 @@ mod tests {
                     join_id: None,
                     role: crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState,
                     init: crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost, // Phase 228
+                    #[cfg(feature = "normalized_dev")]
+                    binding_id: None,
                 },
                 CarrierVar {
                     name: "sum".to_string(),
@@ -194,6 +198,8 @@ mod tests {
                     join_id: None,
                     role: crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState,
                     init: crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost, // Phase 228
+                    #[cfg(feature = "normalized_dev")]
+                    binding_id: None,
                 },
             ],
         );
@@ -240,6 +246,8 @@ mod tests {
                 join_id: None,
                 role: crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState,
                 init: crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost, // Phase 228
+                #[cfg(feature = "normalized_dev")]
+                binding_id: None,
             }],
         );
 
@@ -270,6 +278,8 @@ mod tests {
                 join_id: None,
                 role: crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState,
                 init: crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost, // Phase 228
+                #[cfg(feature = "normalized_dev")]
+                binding_id: None,
             }],
         );
 
@@ -300,6 +310,8 @@ mod tests {
                 join_id: None,
                 role: crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState,
                 init: crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost, // Phase 228
+                #[cfg(feature = "normalized_dev")]
+                binding_id: None,
             }],
         );
 
@@ -333,6 +345,8 @@ mod tests {
                 join_id: None,
                 role: crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState,
                 init: crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost, // Phase 228
+                #[cfg(feature = "normalized_dev")]
+                binding_id: None,
             }],
         );
 
diff --git a/src/mir/builder/control_flow/joinir/patterns/exit_binding_applicator.rs b/src/mir/builder/control_flow/joinir/patterns/exit_binding_applicator.rs
index 207bd437..669311e6 100644
--- a/src/mir/builder/control_flow/joinir/patterns/exit_binding_applicator.rs
+++ b/src/mir/builder/control_flow/joinir/patterns/exit_binding_applicator.rs
@@ -108,6 +108,8 @@ mod tests {
                 join_id: None,
                 role: crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState,
                 init: crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost, // Phase 228
+                #[cfg(feature = "normalized_dev")]
+                binding_id: None,
             }],
         );
 
diff --git a/src/mir/builder/control_flow/joinir/patterns/exit_binding_constructor.rs b/src/mir/builder/control_flow/joinir/patterns/exit_binding_constructor.rs
index 3d1d118d..8082f753 100644
--- a/src/mir/builder/control_flow/joinir/patterns/exit_binding_constructor.rs
+++ b/src/mir/builder/control_flow/joinir/patterns/exit_binding_constructor.rs
@@ -92,6 +92,8 @@ mod tests {
                 join_id: None,
                 role: crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState,
                 init: crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost, // Phase 228
+                #[cfg(feature = "normalized_dev")]
+                binding_id: None,
             }],
         );
 
@@ -131,6 +133,8 @@ mod tests {
                     join_id: None,
                     role: crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState,
                     init: crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost, // Phase 228
+                    #[cfg(feature = "normalized_dev")]
+                    binding_id: None,
                 },
                 CarrierVar {
                     name: "sum".to_string(),
@@ -138,6 +142,8 @@ mod tests {
                     join_id: None,
                     role: crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState,
                     init: crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost, // Phase 228
+                    #[cfg(feature = "normalized_dev")]
+                    binding_id: None,
                 },
             ],
         );
diff --git a/src/mir/builder/control_flow/joinir/patterns/exit_binding_validator.rs b/src/mir/builder/control_flow/joinir/patterns/exit_binding_validator.rs
index a9b56b71..4b234285 100644
--- a/src/mir/builder/control_flow/joinir/patterns/exit_binding_validator.rs
+++ b/src/mir/builder/control_flow/joinir/patterns/exit_binding_validator.rs
@@ -68,6 +68,8 @@ mod tests {
                 join_id: None,
                 role: crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState,
                 init: crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost, // Phase 228
+                #[cfg(feature = "normalized_dev")]
+                binding_id: None,
             }],
         );
 
@@ -89,6 +91,8 @@ mod tests {
                     join_id: None,
                     role: crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState,
                     init: crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost, // Phase 228
+                    #[cfg(feature = "normalized_dev")]
+                    binding_id: None,
                 },
                 CarrierVar {
                     name: "sum".to_string(),
@@ -96,6 +100,8 @@ mod tests {
                     join_id: None,
                     role: crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState,
                     init: crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost, // Phase 228
+                    #[cfg(feature = "normalized_dev")]
+                    binding_id: None,
                 },
             ],
         );
@@ -120,6 +126,8 @@ mod tests {
                 join_id: None,
                 role: crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState,
                 init: crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost, // Phase 228
+                #[cfg(feature = "normalized_dev")]
+                binding_id: None,
             }],
         );
 
@@ -142,6 +150,8 @@ mod tests {
                 join_id: None,
                 role: crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState,
                 init: crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost, // Phase 228
+                #[cfg(feature = "normalized_dev")]
+                binding_id: None,
             }],
         );
 
@@ -164,6 +174,8 @@ mod tests {
                 join_id: None,
                 role: crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState,
                 init: crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost, // Phase 228
+                #[cfg(feature = "normalized_dev")]
+                binding_id: None,
             }],
         );
 
diff --git a/src/mir/builder/control_flow/joinir/patterns/pattern2_with_break.rs b/src/mir/builder/control_flow/joinir/patterns/pattern2_with_break.rs
index bf9f4dbf..c37ae70e 100644
--- a/src/mir/builder/control_flow/joinir/patterns/pattern2_with_break.rs
+++ b/src/mir/builder/control_flow/joinir/patterns/pattern2_with_break.rs
@@ -242,6 +242,8 @@ fn promote_and_prepare_carriers(
         Some(&inputs.scope),
     );
 
+    let mut promoted_pairs: Vec<(String, String)> = Vec::new();
+
     if cond_scope.has_loop_body_local() {
         let promotion_req = ConditionPromotionRequest {
             loop_param_name: &inputs.loop_var_name,
@@ -260,6 +262,26 @@ fn promote_and_prepare_carriers(
                 promoted_var,
                 carrier_name,
             } => {
+                promoted_pairs.push((promoted_var.clone(), carrier_name.clone()));
+
+                #[cfg(feature = "normalized_dev")]
+                {
+                    use crate::mir::join_ir::lowering::carrier_binding_assigner::CarrierBindingAssigner;
+                    let mut promoted_carrier = promoted_carrier;
+                    CarrierBindingAssigner::assign_promoted_binding(
+                        builder,
+                        &mut promoted_carrier,
+                        &promoted_var,
+                        &carrier_name,
+                    )
+                    .map_err(|e| format!("[phase78/binding_assign] {:?}", e))?;
+                    inputs.carrier_info.merge_from(&promoted_carrier);
+                }
+                #[cfg(not(feature = "normalized_dev"))]
+                {
+                    inputs.carrier_info.merge_from(&promoted_carrier);
+                }
+
                 log_pattern2(
                     verbose,
                     "cond_promoter",
@@ -273,7 +295,6 @@ fn promote_and_prepare_carriers(
                     .carrier_info
                     .promoted_loopbodylocals
                     .push(promoted_var.clone());
-                inputs.carrier_info.merge_from(&promoted_carrier);
 
                 log_pattern2(
                     verbose,
@@ -346,6 +367,12 @@ fn promote_and_prepare_carriers(
     for carrier in &mut inputs.carrier_info.carriers {
         let carrier_join_id = inputs.join_value_space.alloc_param();
         carrier.join_id = Some(carrier_join_id);
+        #[cfg(feature = "normalized_dev")]
+        if let Some(binding_id) = carrier.binding_id {
+            inputs
+                .env
+                .register_carrier_binding(binding_id, carrier_join_id);
+        }
         log_pattern2(
             verbose,
             "phase224d",
@@ -356,50 +383,26 @@ fn promote_and_prepare_carriers(
         );
     }
 
-    for promoted_var in &inputs.carrier_info.promoted_loopbodylocals {
-        let candidate_names = vec![
-            format!("is_{}", promoted_var),
-            format!("is_{}_match", promoted_var),
-        ];
-
-        for carrier_name in candidate_names {
-            if carrier_name == inputs.carrier_info.loop_var_name {
-                if let Some(join_id) = inputs.env.get(&inputs.carrier_info.loop_var_name) {
-                    inputs
-                        .env
-                        .insert(promoted_var.clone(), join_id);
-                    log_pattern2(
-                        verbose,
-                        "phase229",
-                        format!(
-                            "Dynamically resolved promoted '{}' → loop_var '{}' (join_id={:?})",
-                            promoted_var, inputs.carrier_info.loop_var_name, join_id
-                        ),
-                    );
-                    break;
-                }
-            }
-
-            if let Some(carrier) = inputs
-                .carrier_info
-                .carriers
-                .iter()
-                .find(|c| c.name == carrier_name)
-            {
-                if let Some(join_id) = carrier.join_id {
-                    inputs.env.insert(promoted_var.clone(), join_id);
-                    log_pattern2(
-                        verbose,
-                        "phase229",
-                        format!(
-                            "Dynamically resolved promoted '{}' → carrier '{}' (join_id={:?})",
-                            promoted_var, carrier_name, join_id
-                        ),
-                    );
-                    break;
-                }
-            }
-        }
+    for (promoted_var, promoted_carrier_name) in promoted_pairs {
+        let join_id = inputs
+            .carrier_info
+            .find_carrier(&promoted_carrier_name)
+            .and_then(|c| c.join_id)
+            .ok_or_else(|| {
+                format!(
+                    "[phase229] promoted carrier '{}' has no join_id",
+                    promoted_carrier_name
+                )
+            })?;
+        inputs.env.insert(promoted_var.clone(), join_id);
+        log_pattern2(
+            verbose,
+            "phase229",
+            format!(
+                "Resolved promoted '{}' → carrier '{}' (join_id={:?})",
+                promoted_var, promoted_carrier_name, join_id
+            ),
+        );
     }
 
     // ExprLowerer validation (unchanged)
@@ -903,6 +906,127 @@ mod tests {
         }
     }
 
+    #[test]
+    #[cfg(feature = "normalized_dev")]
+    fn phase78_promoted_binding_is_recorded_for_digitpos() {
+        use super::super::pattern_pipeline::{build_pattern_context, PatternVariant};
+        use crate::ast::Span;
+        use crate::mir::ValueId;
+
+        let mut builder = MirBuilder::new();
+        builder.variable_map.insert("i".to_string(), ValueId(1));
+        builder.variable_map.insert("len".to_string(), ValueId(2));
+        builder.variable_map.insert("s".to_string(), ValueId(3));
+        builder.variable_map.insert("digits".to_string(), ValueId(4));
+        builder.variable_map.insert("result".to_string(), ValueId(5));
+
+        let condition = bin(BinaryOperator::Less, var("i"), var("len"));
+
+        let local_ch = ASTNode::Local {
+            variables: vec!["ch".to_string()],
+            initial_values: vec![Some(Box::new(ASTNode::MethodCall {
+                object: Box::new(var("s")),
+                method: "substring".to_string(),
+                arguments: vec![],
+                span: Span::unknown(),
+            }))],
+            span: Span::unknown(),
+        };
+        let local_digit_pos = ASTNode::Local {
+            variables: vec!["digit_pos".to_string()],
+            initial_values: vec![Some(Box::new(ASTNode::MethodCall {
+                object: Box::new(var("digits")),
+                method: "indexOf".to_string(),
+                arguments: vec![var("ch")],
+                span: Span::unknown(),
+            }))],
+            span: Span::unknown(),
+        };
+
+        let break_if = ASTNode::If {
+            condition: Box::new(bin(BinaryOperator::Less, var("digit_pos"), lit_i(0))),
+            then_body: vec![ASTNode::Break { span: Span::unknown() }],
+            else_body: None,
+            span: Span::unknown(),
+        };
+
+        let body = vec![
+            local_ch,
+            local_digit_pos,
+            break_if,
+            ASTNode::Assignment {
+                target: Box::new(var("result")),
+                value: Box::new(bin(
+                    BinaryOperator::Add,
+                    bin(BinaryOperator::Multiply, var("result"), lit_i(10)),
+                    var("digit_pos"),
+                )),
+                span: Span::unknown(),
+            },
+            ASTNode::Assignment {
+                target: Box::new(var("i")),
+                value: Box::new(bin(BinaryOperator::Add, var("i"), lit_i(1))),
+                span: Span::unknown(),
+            },
+        ];
+
+        let ctx = build_pattern_context(&mut builder, &condition, &body, PatternVariant::Pattern2)
+            .expect("build_pattern_context");
+        let mut inputs =
+            prepare_pattern2_inputs(&builder, &condition, &body, None, &ctx, false)
+                .expect("prepare_pattern2_inputs");
+
+        promote_and_prepare_carriers(&mut builder, &condition, &body, &mut inputs, false, false)
+            .expect("promote_and_prepare_carriers");
+
+        assert!(
+            inputs
+                .carrier_info
+                .promoted_loopbodylocals
+                .contains(&"digit_pos".to_string()),
+            "digit_pos should be recorded as promoted"
+        );
+        assert_eq!(
+            inputs.carrier_info.promoted_bindings.len(),
+            1,
+            "promoted_bindings should contain exactly one mapping"
+        );
+
+        let (original_bid, promoted_bid) = inputs
+            .carrier_info
+            .promoted_bindings
+            .iter()
+            .next()
+            .map(|(k, v)| (*k, *v))
+            .unwrap();
+
+        let promoted_carrier = inputs
+            .carrier_info
+            .find_carrier("is_digit_pos")
+            .expect("promoted carrier exists");
+
+        assert_eq!(
+            promoted_carrier.binding_id,
+            Some(promoted_bid),
+            "CarrierVar.binding_id should be set for promoted carrier"
+        );
+
+        let promoted_join_id = promoted_carrier.join_id.expect("join_id allocated");
+        assert_eq!(
+            inputs.env.binding_id_map.get(&promoted_bid).copied(),
+            Some(promoted_join_id),
+            "ConditionEnv should register promoted binding_id -> join_id"
+        );
+        assert_eq!(
+            inputs.env.get("digit_pos"),
+            Some(promoted_join_id),
+            "Name-based alias (digit_pos -> is_digit_pos) should be installed for legacy paths"
+        );
+
+        // Ensure the mapping is not degenerate.
+        assert_ne!(original_bid, promoted_bid);
+    }
+
     #[test]
     fn parse_number_like_loop_is_routed_to_pattern2() {
         let condition = bin(BinaryOperator::Less, var("p"), var("len"));
diff --git a/src/mir/builder/control_flow/joinir/patterns/pattern4_carrier_analyzer.rs b/src/mir/builder/control_flow/joinir/patterns/pattern4_carrier_analyzer.rs
index 2f6d88a5..fcdcb5ee 100644
--- a/src/mir/builder/control_flow/joinir/patterns/pattern4_carrier_analyzer.rs
+++ b/src/mir/builder/control_flow/joinir/patterns/pattern4_carrier_analyzer.rs
@@ -278,6 +278,8 @@ mod tests {
                     join_id: None,
                     role: crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState,
                     init: crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost, // Phase 228
+                    #[cfg(feature = "normalized_dev")]
+                    binding_id: None,
                 },
                 CarrierVar {
                     name: "sum".to_string(),
@@ -285,6 +287,8 @@ mod tests {
                     join_id: None,
                     role: crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState,
                     init: crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost, // Phase 228
+                    #[cfg(feature = "normalized_dev")]
+                    binding_id: None,
                 },
                 CarrierVar {
                     name: "M".to_string(),
@@ -292,6 +296,8 @@ mod tests {
                     join_id: None,
                     role: crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState,
                     init: crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost, // Phase 228
+                    #[cfg(feature = "normalized_dev")]
+                    binding_id: None,
                 },
             ],
             trim_helper: None,
diff --git a/src/mir/builder/control_flow/joinir/patterns/pattern4_with_continue.rs b/src/mir/builder/control_flow/joinir/patterns/pattern4_with_continue.rs
index 010193ce..fc48fb7c 100644
--- a/src/mir/builder/control_flow/joinir/patterns/pattern4_with_continue.rs
+++ b/src/mir/builder/control_flow/joinir/patterns/pattern4_with_continue.rs
@@ -257,7 +257,23 @@ fn prepare_pattern4_context(
                     ),
                 );
 
-                carrier_info.merge_from(&promoted_carrier);
+                #[cfg(feature = "normalized_dev")]
+                {
+                    use crate::mir::join_ir::lowering::carrier_binding_assigner::CarrierBindingAssigner;
+                    let mut promoted_carrier = promoted_carrier;
+                    CarrierBindingAssigner::assign_promoted_binding(
+                        builder,
+                        &mut promoted_carrier,
+                        &promoted_var,
+                        &carrier_name,
+                    )
+                    .map_err(|e| format!("[phase78/binding_assign] {:?}", e))?;
+                    carrier_info.merge_from(&promoted_carrier);
+                }
+                #[cfg(not(feature = "normalized_dev"))]
+                {
+                    carrier_info.merge_from(&promoted_carrier);
+                }
 
                 trace::trace().debug(
                     "pattern4/cond_promoter",
diff --git a/src/mir/builder/control_flow/joinir/patterns/pattern_pipeline.rs b/src/mir/builder/control_flow/joinir/patterns/pattern_pipeline.rs
index 81515fdd..de84bbde 100644
--- a/src/mir/builder/control_flow/joinir/patterns/pattern_pipeline.rs
+++ b/src/mir/builder/control_flow/joinir/patterns/pattern_pipeline.rs
@@ -403,6 +403,8 @@ mod tests {
                         join_id: None,
                         role: crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState,
                         init: crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost, // Phase 228
+                        #[cfg(feature = "normalized_dev")]
+                        binding_id: None,
                     },
                     CarrierVar {
                         name: "count".to_string(),
@@ -410,6 +412,8 @@ mod tests {
                         join_id: None,
                         role: crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState,
                         init: crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost, // Phase 228
+                        #[cfg(feature = "normalized_dev")]
+                        binding_id: None,
                     },
                 ],
                 trim_helper: None,
diff --git a/src/mir/join_ir/lowering/carrier_binding_assigner.rs b/src/mir/join_ir/lowering/carrier_binding_assigner.rs
new file mode 100644
index 00000000..fb0c3aeb
--- /dev/null
+++ b/src/mir/join_ir/lowering/carrier_binding_assigner.rs
@@ -0,0 +1,335 @@
+//! CarrierBindingAssigner - Assigns BindingIds to promoted carriers
+//!
+//! Solves the "synthetic carrier has no BindingId" problem by allocating
+//! dedicated BindingIds for promoted carriers (e.g., is_digit_pos, is_ch_match).
+//!
+//! # Problem
+//!
+//! Phase 77's PromotedBindingRecorder expects both original and promoted names
+//! to exist in builder.binding_map, but promoted names are synthetic and don't exist.
+//!
+//! # Solution (Phase 78)
+//!
+//! This box allocates BindingIds for synthetic carriers and records the mapping:
+//!
+//! 1. Get original BindingId from builder.binding_map (Fail-Fast if missing)
+//! 2. Allocate new BindingId for promoted carrier
+//! 3. Record mapping in carrier_info.promoted_bindings
+//! 4. Set binding_id field on the promoted CarrierVar
+//!
+//! # Integration Point (Important!)
+//!
+//! **DO NOT call this from DigitPosPromoter or TrimPromoter**. Those run during
+//! pattern detection phase and don't have access to MirBuilder.
+//!
+//! **INSTEAD, call this from Pattern2/4 lowering code** after receiving the
+//! promoted CarrierInfo:
+//!
+//! ```ignore
+//! // In Pattern2WithBreak::lower() or similar lowering code that has builder access:
+//!
+//! // After receiving promoted CarrierInfo from DigitPosPromoter
+//! if let Some(promoted_var_name) = /* extract from promotion result */ {
+//!     // Assign BindingId for promoted carrier
+//!     CarrierBindingAssigner::assign_promoted_binding(
+//!         builder,
+//!         &mut carrier_info,
+//!         "digit_pos",       // original_name (from promotion result)
+//!         "is_digit_pos"     // promoted_carrier_name (from carrier_info)
+//!     )?;
+//! }
+//!
+//! // Continue with normal lowering...
+//! ```
+//!
+//! # Example
+//!
+//! ```ignore
+//! // DigitPos promotion: "digit_pos" → "is_digit_pos"
+//! CarrierBindingAssigner::assign_promoted_binding(
+//!     builder,
+//!     carrier_info,
+//!     "digit_pos",       // original_name
+//!     "is_digit_pos"     // promoted_carrier_name
+//! )?;
+//! // Result:
+//! // - carrier_info.promoted_bindings[BindingId(5)] = BindingId(10)
+//! // - carrier_info.carriers["is_digit_pos"].binding_id = Some(BindingId(10))
+//! ```
+
+use crate::mir::MirBuilder;
+use crate::mir::join_ir::lowering::carrier_info::CarrierInfo;
+
+#[derive(Debug)]
+pub enum CarrierBindingError {
+    CarrierNotFound(String),
+}
+
+pub struct CarrierBindingAssigner;
+
+impl CarrierBindingAssigner {
+    /// Assign BindingIds to promoted carriers and record in promoted_bindings.
+    ///
+    /// For DigitPos: original_name="digit_pos", promoted_carrier_name="is_digit_pos"
+    /// For Trim: original_name="ch", promoted_carrier_name="is_ch_match"
+    #[cfg(feature = "normalized_dev")]
+    pub fn assign_promoted_binding(
+        builder: &mut MirBuilder,
+        carrier_info: &mut CarrierInfo,
+        original_name: &str,
+        promoted_carrier_name: &str,
+    ) -> Result<(), CarrierBindingError> {
+        let prev_original = builder.binding_map.get(original_name).copied();
+        let prev_promoted = builder.binding_map.get(promoted_carrier_name).copied();
+
+        // Ensure original BindingId exists (LoopBodyLocal promotion may happen before `local` is lowered).
+        let original_bid = match prev_original {
+            Some(bid) => bid,
+            None => {
+                let bid = builder.allocate_binding_id();
+                builder
+                    .binding_map
+                    .insert(original_name.to_string(), bid);
+                bid
+            }
+        };
+
+        // Ensure promoted carrier BindingId exists (synthetic names are never in source binding_map).
+        let promoted_bid = match prev_promoted {
+            Some(bid) => bid,
+            None => {
+                let bid = builder.allocate_binding_id();
+                builder
+                    .binding_map
+                    .insert(promoted_carrier_name.to_string(), bid);
+                bid
+            }
+        };
+
+        carrier_info.record_promoted_binding(original_bid, promoted_bid);
+
+        let Some(carrier) = carrier_info
+            .carriers
+            .iter_mut()
+            .find(|c| c.name == promoted_carrier_name)
+        else {
+            // Restore builder.binding_map before returning.
+            match prev_original {
+                Some(prev) => {
+                    builder.binding_map.insert(original_name.to_string(), prev);
+                }
+                None => {
+                    builder.binding_map.remove(original_name);
+                }
+            }
+            match prev_promoted {
+                Some(prev) => {
+                    builder
+                        .binding_map
+                        .insert(promoted_carrier_name.to_string(), prev);
+                }
+                None => {
+                    builder.binding_map.remove(promoted_carrier_name);
+                }
+            }
+            return Err(CarrierBindingError::CarrierNotFound(
+                promoted_carrier_name.to_string(),
+            ));
+        };
+        carrier.binding_id = Some(promoted_bid);
+
+        if std::env::var("NYASH_JOINIR_DEBUG").is_ok()
+            || std::env::var("JOINIR_TEST_DEBUG").is_ok()
+        {
+            eprintln!(
+                "[phase78/carrier_assigner] '{}' (BindingId({})) → '{}' (BindingId({}))",
+                original_name,
+                original_bid.0,
+                promoted_carrier_name,
+                promoted_bid.0
+            );
+        }
+
+        // Restore builder.binding_map to avoid leaking synthetic names into the source map.
+        match prev_original {
+            Some(prev) => {
+                builder.binding_map.insert(original_name.to_string(), prev);
+            }
+            None => {
+                builder.binding_map.remove(original_name);
+            }
+        }
+        match prev_promoted {
+            Some(prev) => {
+                builder
+                    .binding_map
+                    .insert(promoted_carrier_name.to_string(), prev);
+            }
+            None => {
+                builder.binding_map.remove(promoted_carrier_name);
+            }
+        }
+
+        Ok(())
+    }
+
+    /// No-op in non-dev builds
+    #[cfg(not(feature = "normalized_dev"))]
+    pub fn assign_promoted_binding(
+        _builder: &mut MirBuilder,
+        _carrier_info: &mut CarrierInfo,
+        _original_name: &str,
+        _promoted_carrier_name: &str,
+    ) -> Result<(), CarrierBindingError> {
+        Ok(())
+    }
+}
+
+#[cfg(all(test, feature = "normalized_dev"))]
+mod tests {
+    use super::*;
+    use crate::mir::ValueId;
+
+    #[test]
+    fn test_assign_promoted_binding_success() {
+        use crate::mir::join_ir::lowering::carrier_info::{CarrierVar, CarrierRole, CarrierInit};
+
+        // Create a MirBuilder with binding_map
+        let mut builder = MirBuilder::new();
+
+        // Add original binding to builder.binding_map
+        let original_bid = builder.allocate_binding_id();
+        builder.binding_map.insert("digit_pos".to_string(), original_bid);
+
+        // Create CarrierInfo with promoted carrier
+        let mut carrier_info = CarrierInfo::with_carriers(
+            "test_loop".to_string(),
+            ValueId(0),
+            vec![CarrierVar {
+                name: "is_digit_pos".to_string(),
+                host_id: ValueId(0),
+                join_id: None,
+                role: CarrierRole::ConditionOnly,
+                init: CarrierInit::BoolConst(false),
+                binding_id: None, // Should be set by assigner
+            }],
+        );
+
+        // Assign promoted binding
+        let result = CarrierBindingAssigner::assign_promoted_binding(
+            &mut builder,
+            &mut carrier_info,
+            "digit_pos",
+            "is_digit_pos",
+        );
+
+        assert!(result.is_ok());
+
+        // Verify: promoted_bindings contains the mapping
+        let promoted_bid = carrier_info.resolve_promoted_with_binding(original_bid);
+        assert!(promoted_bid.is_some());
+
+        // Verify: carrier.binding_id was set
+        let carrier = carrier_info.carriers.iter().find(|c| c.name == "is_digit_pos").unwrap();
+        assert_eq!(carrier.binding_id, promoted_bid);
+    }
+
+    #[test]
+    fn test_assign_promoted_binding_missing_original() {
+        use crate::mir::join_ir::lowering::carrier_info::{CarrierInit, CarrierRole, CarrierVar};
+
+        // Create MirBuilder WITHOUT adding "digit_pos" to binding_map
+        let mut builder = MirBuilder::new();
+
+        let mut carrier_info = CarrierInfo::with_carriers("test_loop".to_string(), ValueId(0), vec![
+            CarrierVar {
+                name: "is_digit_pos".to_string(),
+                host_id: ValueId(0),
+                join_id: None,
+                role: CarrierRole::ConditionOnly,
+                init: CarrierInit::BoolConst(false),
+                binding_id: None,
+            },
+        ]);
+
+        // Should succeed (original/promoted BindingId are allocated on demand).
+        let result = CarrierBindingAssigner::assign_promoted_binding(
+            &mut builder,
+            &mut carrier_info,
+            "digit_pos",
+            "is_digit_pos",
+        );
+
+        assert!(result.is_ok());
+        assert_eq!(carrier_info.promoted_bindings.len(), 1);
+
+        let carrier = carrier_info
+            .carriers
+            .iter()
+            .find(|c| c.name == "is_digit_pos")
+            .unwrap();
+        assert!(carrier.binding_id.is_some());
+    }
+
+    #[test]
+    fn test_assign_promoted_binding_multiple_carriers() {
+        use crate::mir::join_ir::lowering::carrier_info::{CarrierVar, CarrierRole, CarrierInit};
+        let mut builder = MirBuilder::new();
+
+        // Add two original bindings
+        let digit_pos_bid = builder.allocate_binding_id();
+        builder.binding_map.insert("digit_pos".to_string(), digit_pos_bid);
+
+        let ch_bid = builder.allocate_binding_id();
+        builder.binding_map.insert("ch".to_string(), ch_bid);
+
+        let mut carrier_info = CarrierInfo::with_carriers(
+            "test_loop".to_string(),
+            ValueId(0),
+            vec![
+                CarrierVar {
+                    name: "is_digit_pos".to_string(),
+                    host_id: ValueId(0),
+                    join_id: None,
+                    role: CarrierRole::ConditionOnly,
+                    init: CarrierInit::BoolConst(false),
+                    binding_id: None,
+                },
+                CarrierVar {
+                    name: "is_ch_match".to_string(),
+                    host_id: ValueId(0),
+                    join_id: None,
+                    role: CarrierRole::ConditionOnly,
+                    init: CarrierInit::BoolConst(false),
+                    binding_id: None,
+                },
+            ],
+        );
+
+        // Assign both promoted bindings
+        CarrierBindingAssigner::assign_promoted_binding(
+            &mut builder,
+            &mut carrier_info,
+            "digit_pos",
+            "is_digit_pos",
+        ).unwrap();
+
+        CarrierBindingAssigner::assign_promoted_binding(
+            &mut builder,
+            &mut carrier_info,
+            "ch",
+            "is_ch_match",
+        ).unwrap();
+
+        // Verify both mappings exist
+        assert!(carrier_info.resolve_promoted_with_binding(digit_pos_bid).is_some());
+        assert!(carrier_info.resolve_promoted_with_binding(ch_bid).is_some());
+
+        // Verify both carriers have binding_id set
+        let is_digit_pos = carrier_info.carriers.iter().find(|c| c.name == "is_digit_pos").unwrap();
+        assert!(is_digit_pos.binding_id.is_some());
+
+        let is_ch_match = carrier_info.carriers.iter().find(|c| c.name == "is_ch_match").unwrap();
+        assert!(is_ch_match.binding_id.is_some());
+    }
+}
diff --git a/src/mir/join_ir/lowering/carrier_info.rs b/src/mir/join_ir/lowering/carrier_info.rs
index 3e231498..705fd24e 100644
--- a/src/mir/join_ir/lowering/carrier_info.rs
+++ b/src/mir/join_ir/lowering/carrier_info.rs
@@ -25,7 +25,7 @@ use crate::mir::ValueId;
 use std::collections::BTreeMap; // Phase 222.5-D: HashMap → BTreeMap for determinism
 
 #[cfg(feature = "normalized_dev")]
-use crate::mir::BindingId;
+use crate::mir::BindingId; // Phase 76+78: BindingId for promoted carriers
 
 /// Phase 227: CarrierRole - Distinguishes loop state carriers from condition-only carriers
 ///
@@ -120,6 +120,33 @@ pub struct CarrierVar {
     /// - `FromHost`: Use host_id value (regular carriers)
     /// - `BoolConst(false)`: Initialize with false (promoted LoopBodyLocal carriers)
     pub init: CarrierInit,
+    /// Phase 78: BindingId for this carrier (dev-only)
+    ///
+    /// For promoted carriers (e.g., is_digit_pos), this is allocated separately
+    /// by CarrierBindingAssigner. For source-derived carriers, this comes from
+    /// builder.binding_map.
+    ///
+    /// Enables type-safe lookup: BindingId → ValueId (join_id) in ConditionEnv.
+    ///
+    /// # Example
+    ///
+    /// ```ignore
+    /// // Source-derived carrier
+    /// CarrierVar {
+    ///     name: "sum",
+    ///     binding_id: Some(BindingId(5)), // from builder.binding_map["sum"]
+    ///     ..
+    /// }
+    ///
+    /// // Promoted carrier
+    /// CarrierVar {
+    ///     name: "is_digit_pos",
+    ///     binding_id: Some(BindingId(10)), // allocated by CarrierBindingAssigner
+    ///     ..
+    /// }
+    /// ```
+    #[cfg(feature = "normalized_dev")]
+    pub binding_id: Option<BindingId>,
 }
 
 impl CarrierVar {
@@ -134,6 +161,8 @@ impl CarrierVar {
             join_id: None,
             role: CarrierRole::LoopState,
             init: CarrierInit::FromHost, // Phase 228: Default to FromHost
+            #[cfg(feature = "normalized_dev")]
+            binding_id: None, // Phase 78: No BindingId by default
         }
     }
 
@@ -145,6 +174,8 @@ impl CarrierVar {
             join_id: None,
             role,
             init: CarrierInit::FromHost, // Phase 228: Default to FromHost
+            #[cfg(feature = "normalized_dev")]
+            binding_id: None, // Phase 78: No BindingId by default
         }
     }
 
@@ -161,6 +192,8 @@ impl CarrierVar {
             join_id: None,
             role,
             init,
+            #[cfg(feature = "normalized_dev")]
+            binding_id: None, // Phase 78: No BindingId by default
         }
     }
 }
@@ -275,6 +308,8 @@ impl CarrierInfo {
                 join_id: None, // Phase 177-STRUCT-1: Set by header PHI generation
                 role: CarrierRole::LoopState, // Phase 227: Default to LoopState
                 init: CarrierInit::FromHost, // Phase 228: Default to FromHost
+                #[cfg(feature = "normalized_dev")]
+                binding_id: None, // Phase 78: Set by CarrierBindingAssigner
             })
             .collect();
 
@@ -338,6 +373,8 @@ impl CarrierInfo {
                 join_id: None, // Phase 177-STRUCT-1: Set by header PHI generation
                 role: CarrierRole::LoopState, // Phase 227: Default to LoopState
                 init: CarrierInit::FromHost, // Phase 228: Default to FromHost
+                #[cfg(feature = "normalized_dev")]
+                binding_id: None, // Phase 78: Set by CarrierBindingAssigner
             });
         }
 
@@ -613,10 +650,12 @@ impl CarrierInfo {
     /// we integrate BindingId tracking into the promotion pipeline.
     #[cfg(feature = "normalized_dev")]
     pub fn record_promoted_binding(&mut self, original_binding: BindingId, promoted_binding: BindingId) {
-        eprintln!(
-            "[digitpos_promoter/phase76] Recorded promoted binding: {} → {}",
-            original_binding, promoted_binding
-        );
+        if std::env::var("NYASH_JOINIR_DEBUG").is_ok() || std::env::var("JOINIR_TEST_DEBUG").is_ok() {
+            eprintln!(
+                "[binding_pilot/promoted_bindings] {} → {}",
+                original_binding, promoted_binding
+            );
+        }
         self.promoted_bindings.insert(original_binding, promoted_binding);
     }
 }
@@ -809,6 +848,8 @@ mod tests {
             join_id: None,                // Phase 177-STRUCT-1
             role: CarrierRole::LoopState, // Phase 227: Default to LoopState
             init: CarrierInit::FromHost,  // Phase 228: Default to FromHost
+            #[cfg(feature = "normalized_dev")]
+            binding_id: None, // Phase 78: No BindingId by default
         }
     }
 
diff --git a/src/mir/join_ir/lowering/carrier_update_emitter.rs b/src/mir/join_ir/lowering/carrier_update_emitter.rs
index dc713804..f2ea3dd3 100644
--- a/src/mir/join_ir/lowering/carrier_update_emitter.rs
+++ b/src/mir/join_ir/lowering/carrier_update_emitter.rs
@@ -401,6 +401,8 @@ mod tests {
             join_id: None, // Phase 177-STRUCT-1
             role: crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState,
             init: crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost, // Phase 228
+            #[cfg(feature = "normalized_dev")]
+            binding_id: None,
         }
     }
 
diff --git a/src/mir/join_ir/lowering/condition_env.rs b/src/mir/join_ir/lowering/condition_env.rs
index 1cc130d5..a7065cae 100644
--- a/src/mir/join_ir/lowering/condition_env.rs
+++ b/src/mir/join_ir/lowering/condition_env.rs
@@ -172,6 +172,33 @@ impl ConditionEnv {
         }
     }
 
+    /// Phase 78: Register a carrier binding (BindingId → ValueId)
+    ///
+    /// Used by Pattern2/4 lowering to register promoted carriers so they can
+    /// be looked up via BindingId.
+    ///
+    /// # Arguments
+    ///
+    /// * `binding_id` - BindingId for the carrier (allocated by CarrierBindingAssigner)
+    /// * `join_value_id` - JoinIR-local ValueId for this carrier (after header PHI)
+    ///
+    /// # Example
+    ///
+    /// ```ignore
+    /// // After allocating carrier join_id
+    /// if let Some(binding_id) = carrier.binding_id {
+    ///     condition_env.register_carrier_binding(binding_id, carrier.join_id.unwrap());
+    /// }
+    /// ```
+    #[cfg(feature = "normalized_dev")]
+    pub fn register_carrier_binding(
+        &mut self,
+        binding_id: BindingId,
+        join_value_id: ValueId,
+    ) {
+        self.binding_id_map.insert(binding_id, join_value_id);
+    }
+
     /// Phase 75: Resolve variable with BindingId priority (dev-only, pilot integration)
     ///
     /// Look up variable by BindingId first, falling back to name-based lookup.
diff --git a/src/mir/join_ir/lowering/loop_update_analyzer.rs b/src/mir/join_ir/lowering/loop_update_analyzer.rs
index 34429445..8a246e14 100644
--- a/src/mir/join_ir/lowering/loop_update_analyzer.rs
+++ b/src/mir/join_ir/lowering/loop_update_analyzer.rs
@@ -301,6 +301,8 @@ mod tests {
             join_id: None, // Phase 177-STRUCT-1
             role: crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState,
             init: crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost, // Phase 228
+            #[cfg(feature = "normalized_dev")]
+            binding_id: None,
         }];
 
         let updates = LoopUpdateAnalyzer::analyze_carrier_updates(&body, &carriers);
@@ -360,6 +362,8 @@ mod tests {
             join_id: None,
             role: crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState,
             init: crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost, // Phase 228
+            #[cfg(feature = "normalized_dev")]
+            binding_id: None,
         }];
 
         let updates = LoopUpdateAnalyzer::analyze_carrier_updates(&body, &carriers);
@@ -420,6 +424,8 @@ mod tests {
             join_id: None,
             role: crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState,
             init: crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost, // Phase 228
+            #[cfg(feature = "normalized_dev")]
+            binding_id: None,
         }];
 
         let updates = LoopUpdateAnalyzer::analyze_carrier_updates(&body, &carriers);
@@ -480,6 +486,8 @@ mod tests {
             join_id: None,
             role: crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState,
             init: crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost, // Phase 228
+            #[cfg(feature = "normalized_dev")]
+            binding_id: None,
         }];
 
         let updates = LoopUpdateAnalyzer::analyze_carrier_updates(&body, &carriers);
@@ -519,6 +527,8 @@ mod tests {
             join_id: None,
             role: crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState,
             init: crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost,
+            #[cfg(feature = "normalized_dev")]
+            binding_id: None,
         }];
 
         let updates = LoopUpdateAnalyzer::analyze_carrier_updates(&body, &carriers);
@@ -605,6 +615,8 @@ mod tests {
                 join_id: None,
                 role: crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState,
                 init: crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost,
+                #[cfg(feature = "normalized_dev")]
+                binding_id: None,
             },
             CarrierVar {
                 name: "i".to_string(),
@@ -612,6 +624,8 @@ mod tests {
                 join_id: None,
                 role: crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState,
                 init: crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost,
+                #[cfg(feature = "normalized_dev")]
+                binding_id: None,
             },
         ];
 
diff --git a/src/mir/join_ir/lowering/mod.rs b/src/mir/join_ir/lowering/mod.rs
index dd415e0b..e88f14c7 100644
--- a/src/mir/join_ir/lowering/mod.rs
+++ b/src/mir/join_ir/lowering/mod.rs
@@ -20,6 +20,7 @@
 //! - `loop_pattern_router.rs`: Phase 33-12 Loop pattern routing (Pattern 1-4 dispatcher)
 
 pub(crate) mod bool_expr_lowerer; // Phase 168: Boolean expression lowering (unused - candidate for removal)
+pub mod carrier_binding_assigner; // Phase 78: BindingId assignment for promoted carriers (dev-only)
 pub mod carrier_info; // Phase 196: Carrier metadata for loop lowering
 pub(crate) mod carrier_update_emitter; // Phase 179: Carrier update instruction emission
 pub(crate) mod common; // Internal lowering utilities
diff --git a/src/mir/join_ir/lowering/scope_manager.rs b/src/mir/join_ir/lowering/scope_manager.rs
index e1f25823..0273a636 100644
--- a/src/mir/join_ir/lowering/scope_manager.rs
+++ b/src/mir/join_ir/lowering/scope_manager.rs
@@ -361,6 +361,8 @@ mod tests {
                 join_id: Some(ValueId(101)),
                 role: CarrierRole::LoopState,
                 init: CarrierInit::FromHost,
+                #[cfg(feature = "normalized_dev")]
+                binding_id: None,
             }],
             trim_helper: None,
             promoted_loopbodylocals: vec![],
@@ -393,6 +395,8 @@ mod tests {
                 join_id: Some(ValueId(102)),
                 role: CarrierRole::ConditionOnly,
                 init: CarrierInit::BoolConst(false),
+                #[cfg(feature = "normalized_dev")]
+                binding_id: None,
             }],
             trim_helper: None,
             promoted_loopbodylocals: vec!["digit_pos".to_string()],
diff --git a/src/mir/join_ir/ownership/plan_to_lowering.rs b/src/mir/join_ir/ownership/plan_to_lowering.rs
index 58fda7ef..9f15767d 100644
--- a/src/mir/join_ir/ownership/plan_to_lowering.rs
+++ b/src/mir/join_ir/ownership/plan_to_lowering.rs
@@ -71,6 +71,8 @@ pub fn plan_to_p2_inputs(
             init: CarrierInit::FromHost, // Default (Phase 228)
             host_id: crate::mir::ValueId(0), // Placeholder - not used in dev analysis
             join_id: None,
+            #[cfg(feature = "normalized_dev")]
+            binding_id: None,
         });
     }
 
@@ -128,6 +130,8 @@ pub fn plan_to_p2_inputs_with_relay(
             init: CarrierInit::FromHost,
             host_id: crate::mir::ValueId(0),
             join_id: None,
+            #[cfg(feature = "normalized_dev")]
+            binding_id: None,
         });
     }
 
@@ -175,6 +179,8 @@ pub fn plan_to_p2_inputs_with_relay(
             init: CarrierInit::FromHost,
             host_id: crate::mir::ValueId(0),
             join_id: None,
+            #[cfg(feature = "normalized_dev")]
+            binding_id: None,
         });
     }
 
@@ -237,6 +243,8 @@ pub fn plan_to_p3_inputs(
             init: CarrierInit::FromHost, // Default (Phase 228)
             host_id: crate::mir::ValueId(0), // Placeholder - not used in dev analysis
             join_id: None,
+            #[cfg(feature = "normalized_dev")]
+            binding_id: None,
         });
     }
 
diff --git a/src/mir/loop_pattern_detection/loop_body_carrier_promoter.rs b/src/mir/loop_pattern_detection/loop_body_carrier_promoter.rs
index 13fb91d2..cf934f7c 100644
--- a/src/mir/loop_pattern_detection/loop_body_carrier_promoter.rs
+++ b/src/mir/loop_pattern_detection/loop_body_carrier_promoter.rs
@@ -173,11 +173,13 @@ impl LoopBodyCarrierPromoter {
             };
         }
 
-        eprintln!(
-            "[promoter/pattern5] Phase 171-C: Found {} LoopBodyLocal variables: {:?}",
-            body_locals.len(),
-            body_locals
-        );
+        if std::env::var("NYASH_JOINIR_DEBUG").is_ok() || std::env::var("JOINIR_TEST_DEBUG").is_ok() {
+            eprintln!(
+                "[promoter/pattern5] Phase 171-C: Found {} LoopBodyLocal variables: {:?}",
+                body_locals.len(),
+                body_locals
+            );
+        }
 
         // 2. break 条件を取得
         if request.break_cond.is_none() {
@@ -194,10 +196,12 @@ impl LoopBodyCarrierPromoter {
             // Phase 79: Use TrimDetector for pure detection logic
             if let Some(detection) = TrimDetector::detect(break_cond, request.loop_body, var_name)
             {
-                eprintln!(
-                    "[promoter/pattern5] Trim pattern detected! var='{}', literals={:?}",
-                    detection.match_var, detection.comparison_literals
-                );
+                if std::env::var("NYASH_JOINIR_DEBUG").is_ok() || std::env::var("JOINIR_TEST_DEBUG").is_ok() {
+                    eprintln!(
+                        "[promoter/pattern5] Trim pattern detected! var='{}', literals={:?}",
+                        detection.match_var, detection.comparison_literals
+                    );
+                }
 
                 // 昇格成功！
                 let trim_info = TrimPatternInfo {
@@ -224,21 +228,23 @@ impl LoopBodyCarrierPromoter {
     // - extract_equality_literals
 }
 
-/// Phase 78: Log promotion errors with clear messages (for Trim pattern)
+/// Phase 78: Log promotion errors with clear messages (for Trim pattern, gated)
 #[cfg(feature = "normalized_dev")]
 fn log_trim_promotion_error(error: &BindingRecordError) {
-    match error {
-        BindingRecordError::OriginalNotFound(name) => {
-            eprintln!(
-                "[trim_lowerer/warning] Original variable '{}' not found in binding_map",
-                name
-            );
-        }
-        BindingRecordError::PromotedNotFound(name) => {
-            eprintln!(
-                "[trim_lowerer/warning] Promoted variable '{}' not found in binding_map",
-                name
-            );
+    if std::env::var("NYASH_JOINIR_DEBUG").is_ok() || std::env::var("JOINIR_TEST_DEBUG").is_ok() {
+        match error {
+            BindingRecordError::OriginalNotFound(name) => {
+                eprintln!(
+                    "[binding_pilot/trim] Original variable '{}' not found in binding_map",
+                    name
+                );
+            }
+            BindingRecordError::PromotedNotFound(name) => {
+                eprintln!(
+                    "[binding_pilot/trim] Promoted variable '{}' not found in binding_map",
+                    name
+                );
+            }
         }
     }
 }
diff --git a/src/mir/loop_pattern_detection/loop_body_digitpos_promoter.rs b/src/mir/loop_pattern_detection/loop_body_digitpos_promoter.rs
index 60302031..cc0d5d75 100644
--- a/src/mir/loop_pattern_detection/loop_body_digitpos_promoter.rs
+++ b/src/mir/loop_pattern_detection/loop_body_digitpos_promoter.rs
@@ -129,11 +129,13 @@ impl DigitPosPromoter {
             };
         }
 
-        eprintln!(
-            "[digitpos_promoter] Phase 224: Found {} LoopBodyLocal variables: {:?}",
-            body_locals.len(),
-            body_locals
-        );
+        if std::env::var("NYASH_JOINIR_DEBUG").is_ok() || std::env::var("JOINIR_TEST_DEBUG").is_ok() {
+            eprintln!(
+                "[digitpos_promoter] Phase 224: Found {} LoopBodyLocal variables: {:?}",
+                body_locals.len(),
+                body_locals
+            );
+        }
 
         // Step 2: Get condition AST
         let condition = req.break_cond.or(req.continue_cond);
@@ -160,10 +162,12 @@ impl DigitPosPromoter {
         }
 
         let detection = detection.unwrap();
-        eprintln!(
-            "[digitpos_promoter] Pattern detected: {} → {} (bool) + {} (int)",
-            detection.var_name, detection.bool_carrier_name, detection.int_carrier_name
-        );
+        if std::env::var("NYASH_JOINIR_DEBUG").is_ok() || std::env::var("JOINIR_TEST_DEBUG").is_ok() {
+            eprintln!(
+                "[digitpos_promoter] Pattern detected: {} → {} (bool) + {} (int)",
+                detection.var_name, detection.bool_carrier_name, detection.int_carrier_name
+            );
+        }
 
         // Step 4: Build CarrierInfo
         use crate::mir::join_ir::lowering::carrier_info::{
@@ -177,6 +181,8 @@ impl DigitPosPromoter {
             join_id: None,       // Will be allocated later
             role: CarrierRole::ConditionOnly, // Phase 227: DigitPos is condition-only
             init: CarrierInit::BoolConst(false), // Phase 228: Initialize with false
+            #[cfg(feature = "normalized_dev")]
+            binding_id: None, // Phase 78: Set by CarrierBindingAssigner
         };
 
         // Integer carrier (loop-state, for NumberAccumulation)
@@ -186,6 +192,8 @@ impl DigitPosPromoter {
             join_id: None,       // Will be allocated later
             role: CarrierRole::LoopState, // Phase 247-EX: LoopState for accumulation
             init: CarrierInit::LoopLocalZero, // Derived in-loop carrier (no host binding)
+            #[cfg(feature = "normalized_dev")]
+            binding_id: None, // Phase 78: Set by CarrierBindingAssigner
         };
 
         // Create CarrierInfo with a dummy loop_var_name (will be ignored during merge)
@@ -214,14 +222,16 @@ impl DigitPosPromoter {
             log_promotion_error(&e);
         }
 
-        eprintln!(
-            "[digitpos_promoter] Phase 247-EX: A-4 DigitPos pattern promoted: {} → {} (bool) + {} (i64)",
-            detection.var_name, detection.bool_carrier_name, detection.int_carrier_name
-        );
-        eprintln!(
-            "[digitpos_promoter] Phase 229: Recorded promoted variable '{}' (carriers: '{}', '{}')",
-            detection.var_name, detection.bool_carrier_name, detection.int_carrier_name
-        );
+        if std::env::var("NYASH_JOINIR_DEBUG").is_ok() || std::env::var("JOINIR_TEST_DEBUG").is_ok() {
+            eprintln!(
+                "[digitpos_promoter] Phase 247-EX: A-4 DigitPos pattern promoted: {} → {} (bool) + {} (i64)",
+                detection.var_name, detection.bool_carrier_name, detection.int_carrier_name
+            );
+            eprintln!(
+                "[digitpos_promoter] Phase 229: Recorded promoted variable '{}' (carriers: '{}', '{}')",
+                detection.var_name, detection.bool_carrier_name, detection.int_carrier_name
+            );
+        }
 
         DigitPosPromotionResult::Promoted {
             carrier_info,
@@ -239,21 +249,23 @@ impl DigitPosPromoter {
     // - is_substring_method_call
 }
 
-/// Phase 78: Log promotion errors with clear messages
+/// Phase 78: Log promotion errors with clear messages (gated)
 #[cfg(feature = "normalized_dev")]
 fn log_promotion_error(error: &BindingRecordError) {
-    match error {
-        BindingRecordError::OriginalNotFound(name) => {
-            eprintln!(
-                "[digitpos_promoter/warning] Original variable '{}' not found in binding_map",
-                name
-            );
-        }
-        BindingRecordError::PromotedNotFound(name) => {
-            eprintln!(
-                "[digitpos_promoter/warning] Promoted variable '{}' not found in binding_map",
-                name
-            );
+    if std::env::var("NYASH_JOINIR_DEBUG").is_ok() || std::env::var("JOINIR_TEST_DEBUG").is_ok() {
+        match error {
+            BindingRecordError::OriginalNotFound(name) => {
+                eprintln!(
+                    "[binding_pilot/digitpos] Original variable '{}' not found in binding_map",
+                    name
+                );
+            }
+            BindingRecordError::PromotedNotFound(name) => {
+                eprintln!(
+                    "[binding_pilot/digitpos] Promoted variable '{}' not found in binding_map",
+                    name
+                );
+            }
         }
     }
 }