feat(joinir): Phase 228 - CarrierInit for ConditionOnly header PHI initialization

- Add CarrierInit enum (FromHost/BoolConst) for explicit initialization policy
- LoopHeaderPhiBuilder generates Const instruction for BoolConst carriers
- merge/mod.rs uses carrier_info to include ALL carriers in header PHI
- Pattern 2/4 pass carrier_info to boundary builder
- ConditionOnly carriers (is_digit_pos) now included in header PHI

Remaining: latch incoming for ConditionOnly carriers (Phase 228-8)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/mir/builder/control_flow/joinir/merge/loop_header_phi_builder.rs

@@ -51,13 +51,19 @@ impl LoopHeaderPhiBuilder {
     ///
     /// LoopHeaderPhiInfo with allocated PHI dsts.
     /// Note: latch_incoming is not yet set - that happens in instruction_rewriter.
+    ///
+    /// # Phase 228 Update
+    ///
+    /// Added CarrierInit and CarrierRole to carrier tuples:
+    /// * `CarrierInit::FromHost` - Use host_id directly as PHI init value
+    /// * `CarrierInit::BoolConst(val)` - Generate explicit bool constant for ConditionOnly carriers
     pub fn build(
         builder: &mut crate::mir::builder::MirBuilder,
         header_block: BasicBlockId,
         entry_block: BasicBlockId,
         loop_var_name: &str,
         loop_var_init: ValueId,
-        carriers: &[(String, ValueId)], // (name, init_value) pairs
+        carriers: &[(String, ValueId, crate::mir::join_ir::lowering::carrier_info::CarrierInit, crate::mir::join_ir::lowering::carrier_info::CarrierRole)], // Phase 228: Added CarrierInit and CarrierRole
         expr_result_is_loop_var: bool,
         debug: bool,
     ) -> Result<LoopHeaderPhiInfo, String> {
@@ -96,15 +102,35 @@ impl LoopHeaderPhiBuilder {
         }
 
         // Allocate PHIs for other carriers
-        for (name, init_value) in carriers {
+        for (name, host_id, init, role) in carriers {
+            // Phase 228-5: Generate explicit const for BoolConst, use host_id for FromHost
+            let init_value = match init {
+                crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost => *host_id,
+                crate::mir::join_ir::lowering::carrier_info::CarrierInit::BoolConst(val) => {
+                    // Phase 228: Generate explicit bool constant for ConditionOnly carriers
+                    let const_id = builder.next_value_id();
+                    builder.emit_instruction(MirInstruction::Const {
+                        dst: const_id,
+                        value: crate::mir::types::ConstValue::Bool(*val),
+                    });
+                    if debug {
+                        eprintln!(
+                            "[cf_loop/joinir]   Phase 228: Generated const {:?} = Bool({}) for ConditionOnly carrier '{}'",
+                            const_id, val, name
+                        );
+                    }
+                    const_id
+                }
+            };
+
             let phi_dst = builder.next_value_id();
             info.carrier_phis.insert(
                 name.clone(),
                 CarrierPhiEntry {
                     phi_dst,
-                    entry_incoming: (entry_block, *init_value),
+                    entry_incoming: (entry_block, init_value),
                     latch_incoming: None,
-                    role: crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState, // Phase 227: Default to LoopState (will be updated later if needed)
+                    role: *role, // Phase 228: Use role from carrier_info
                 },
             );
             // Phase 177-STRUCT-2: Record insertion order
@@ -112,8 +138,8 @@ impl LoopHeaderPhiBuilder {
 
             if debug {
                 eprintln!(
-                    "[cf_loop/joinir]   Carrier '{}' PHI: {:?} = phi [(from {:?}, {:?}), (latch TBD)]",
-                    name, phi_dst, entry_block, init_value
+                    "[cf_loop/joinir]   Carrier '{}' PHI: {:?} = phi [(from {:?}, {:?}), (latch TBD)], role={:?}",
+                    name, phi_dst, entry_block, init_value, role
                 );
             }
         }

src/mir/builder/control_flow/joinir/merge/mod.rs

@@ -141,12 +141,23 @@ pub(in crate::mir::builder) fn merge_joinir_mir_blocks(
                 "Phase 201-A: No host_inputs in boundary for loop_var_init"
             )?;
 
-            // Extract other carriers from exit_bindings
-            let other_carriers: Vec<(String, ValueId)> = boundary.exit_bindings
-                .iter()
-                .filter(|b| b.carrier_name != *loop_var_name)
-                .map(|b| (b.carrier_name.clone(), b.host_slot))
-                .collect();
+            // Phase 228-4: Extract carriers with their initialization strategy
+            let other_carriers: Vec<(String, ValueId, crate::mir::join_ir::lowering::carrier_info::CarrierInit, crate::mir::join_ir::lowering::carrier_info::CarrierRole)> =
+                if let Some(ref carrier_info) = boundary.carrier_info {
+                    // Use carrier_info if available (Phase 228)
+                    carrier_info.carriers
+                        .iter()
+                        .filter(|c| c.name != *loop_var_name)
+                        .map(|c| (c.name.clone(), c.host_id, c.init, c.role))
+                        .collect()
+                } else {
+                    // Fallback: exit_bindings から取得（既存動作）
+                    boundary.exit_bindings
+                        .iter()
+                        .filter(|b| b.carrier_name != *loop_var_name)
+                        .map(|b| (b.carrier_name.clone(), b.host_slot, crate::mir::join_ir::lowering::carrier_info::CarrierInit::FromHost, crate::mir::join_ir::lowering::carrier_info::CarrierRole::LoopState))
+                        .collect()
+                };
 
             if debug {
                 eprintln!(
@@ -156,7 +167,7 @@ pub(in crate::mir::builder) fn merge_joinir_mir_blocks(
                 eprintln!(
                     "[cf_loop/joinir]   loop_var_init={:?}, carriers={:?}",
                     loop_var_init,
-                    other_carriers.iter().map(|(n, _)| n.as_str()).collect::<Vec<_>>()
+                    other_carriers.iter().map(|(n, _, _, _)| n.as_str()).collect::<Vec<_>>()
                 );
             }
 

src/mir/builder/control_flow/joinir/patterns/common_init.rs

@@ -163,6 +163,7 @@ impl CommonPatternInitializer {
                             host_id: ValueId(0),  // Dummy
                             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
                         })
                     } else {
                         None

src/mir/builder/control_flow/joinir/patterns/exit_binding.rs

@@ -143,6 +143,7 @@ mod tests {
                 host_id: ValueId(10),
                 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
             }],
         );
 
@@ -183,12 +184,14 @@ mod tests {
                     host_id: ValueId(11),
                     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
                 },
                 CarrierVar {
                     name: "sum".to_string(),
                     host_id: ValueId(10),
                     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
                 },
             ],
         );
@@ -232,6 +235,7 @@ mod tests {
                 host_id: ValueId(10),
                 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
             }],
         );
 
@@ -261,6 +265,7 @@ mod tests {
                 host_id: ValueId(10),
                 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
             }],
         );
 
@@ -290,6 +295,7 @@ mod tests {
                 host_id: ValueId(10),
                 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
             }],
         );
 
@@ -322,6 +328,7 @@ mod tests {
                 host_id: ValueId(10),
                 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
             }],
         );
 
@@ -352,6 +359,7 @@ mod tests {
             condition_bindings: vec![],  // Phase 171-fix: Add missing field
             expr_result: None,           // Phase 33-14: Add missing field
             loop_var_name: None,         // Phase 33-16: Add missing field
+            carrier_info: None,          // Phase 228: Add missing field
         };
 
         builder.apply_to_boundary(&mut boundary)

src/mir/builder/control_flow/joinir/patterns/exit_binding_applicator.rs

@@ -108,6 +108,7 @@ mod tests {
                 host_id: ValueId(10),
                 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
             }],
         );
 
@@ -134,6 +135,7 @@ mod tests {
             condition_bindings: vec![],  // Phase 171-fix: Add missing field
             expr_result: None,           // Phase 33-14: Add missing field
             loop_var_name: None,         // Phase 33-16: Add missing field
+            carrier_info: None,          // Phase 228: Add missing field
         };
 
         apply_exit_bindings_to_boundary(&carrier_info, &exit_meta, &variable_map, &mut boundary)

src/mir/builder/control_flow/joinir/patterns/exit_binding_constructor.rs

@@ -92,6 +92,7 @@ mod tests {
                 host_id: ValueId(10),
                 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
             }],
         );
 
@@ -130,12 +131,14 @@ mod tests {
                     host_id: ValueId(11),
                     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
                 },
                 CarrierVar {
                     name: "sum".to_string(),
                     host_id: ValueId(10),
                     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
                 },
             ],
         );

src/mir/builder/control_flow/joinir/patterns/exit_binding_validator.rs

@@ -70,6 +70,7 @@ mod tests {
                 host_id: ValueId(10),
                 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
             }],
         );
 
@@ -90,12 +91,14 @@ mod tests {
                     host_id: ValueId(11),
                     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
                 },
                 CarrierVar {
                     name: "sum".to_string(),
                     host_id: ValueId(10),
                     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
                 },
             ],
         );
@@ -119,6 +122,7 @@ mod tests {
                 host_id: ValueId(10),
                 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
             }],
         );
 
@@ -140,6 +144,7 @@ mod tests {
                 host_id: ValueId(10),
                 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
             }],
         );
 
@@ -161,6 +166,7 @@ mod tests {
                 host_id: ValueId(10),
                 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
             }],
         );
 

src/mir/builder/control_flow/joinir/patterns/pattern2_with_break.rs

@@ -578,6 +578,7 @@ impl MirBuilder {
             .with_exit_bindings(exit_bindings.clone())
             .with_expr_result(fragment_meta.expr_result) // Phase 33-14: Pass expr_result to merger
             .with_loop_var_name(Some(loop_var_name.clone())) // Phase 33-16: For LoopHeaderPhiBuilder
+            .with_carrier_info(carrier_info.clone()) // Phase 228-6: Pass carrier_info for ConditionOnly header PHI init
             .build();
 
         // Phase 33-22: Use JoinIRConversionPipeline for unified conversion flow

src/mir/builder/control_flow/joinir/patterns/pattern4_carrier_analyzer.rs

@@ -277,18 +277,21 @@ mod tests {
                     host_id: ValueId(1),
                     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
                 },
                 CarrierVar {
                     name: "sum".to_string(),
                     host_id: ValueId(2),
                     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
                 },
                 CarrierVar {
                     name: "M".to_string(),
                     host_id: ValueId(3),
                     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
                 },
             ],
             trim_helper: None,

src/mir/builder/control_flow/joinir/patterns/pattern4_with_continue.rs

@@ -378,6 +378,7 @@ impl MirBuilder {
             .with_inputs(join_inputs, host_inputs)  // Dynamic carrier count
             .with_exit_bindings(exit_bindings)
             .with_loop_var_name(Some(loop_var_name.clone()))  // Phase 33-19: Enable exit PHI collection
+            .with_carrier_info(carrier_info.clone()) // Phase 228-6: Pass carrier_info for ConditionOnly header PHI init
             .build();
 
         // Phase 33-22: Use JoinIRConversionPipeline for unified conversion flow

src/mir/builder/control_flow/joinir/patterns/pattern_pipeline.rs

@@ -397,12 +397,14 @@ mod tests {
                         host_id: ValueId(10),
                         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
                     },
                     CarrierVar {
                         name: "count".to_string(),
                         host_id: ValueId(11),
                         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
                     },
                 ],
                 trim_helper: None,

src/mir/join_ir/lowering/carrier_info.rs

@@ -54,6 +54,29 @@ pub enum CarrierRole {
     ConditionOnly,
 }
 
+/// Phase 228: Initialization policy for carrier variables
+///
+/// When carriers participate in header PHI, they need an initial value.
+/// Most carriers use their host_id value (FromHost), but promoted LoopBodyLocal
+/// carriers need explicit bool initialization (BoolConst).
+///
+/// # Example
+///
+/// ```ignore
+/// // Regular carrier (sum): Use host_id value
+/// CarrierVar { name: "sum", host_id: ValueId(10), init: FromHost, .. }
+///
+/// // ConditionOnly carrier (is_digit_pos): Initialize with false
+/// CarrierVar { name: "is_digit_pos", host_id: ValueId(15), init: BoolConst(false), .. }
+/// ```
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum CarrierInit {
+    /// No explicit initialization (use host_id value)
+    FromHost,
+    /// Initialize with bool constant (for ConditionOnly carriers)
+    BoolConst(bool),
+}
+
 /// Phase 224-D: Alias for promoted LoopBodyLocal in condition expressions
 ///
 /// When a LoopBodyLocal variable is promoted to a carrier, the original variable
@@ -97,6 +120,11 @@ pub struct CarrierVar {
     /// - `LoopState`: Value needed after loop (participates in exit PHI)
     /// - `ConditionOnly`: Only used for loop condition (no exit PHI)
     pub role: CarrierRole,
+    /// Phase 228: Initialization policy for header PHI
+    ///
+    /// - `FromHost`: Use host_id value (regular carriers)
+    /// - `BoolConst(false)`: Initialize with false (promoted LoopBodyLocal carriers)
+    pub init: CarrierInit,
 }
 
 impl CarrierVar {
@@ -110,6 +138,7 @@ impl CarrierVar {
             host_id,
             join_id: None,
             role: CarrierRole::LoopState,
+            init: CarrierInit::FromHost, // Phase 228: Default to FromHost
         }
     }
 
@@ -120,6 +149,23 @@ impl CarrierVar {
             host_id,
             join_id: None,
             role,
+            init: CarrierInit::FromHost, // Phase 228: Default to FromHost
+        }
+    }
+
+    /// Phase 228: Create a CarrierVar with explicit role and init policy
+    pub fn with_role_and_init(
+        name: String,
+        host_id: ValueId,
+        role: CarrierRole,
+        init: CarrierInit,
+    ) -> Self {
+        Self {
+            name,
+            host_id,
+            join_id: None,
+            role,
+            init,
         }
     }
 }
@@ -197,6 +243,7 @@ impl CarrierInfo {
                 host_id: id,
                 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
             })
             .collect();
 
@@ -257,6 +304,7 @@ impl CarrierInfo {
                 host_id,
                 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
             });
         }
 
@@ -576,6 +624,7 @@ mod tests {
             host_id: ValueId(id),
             join_id: None, // Phase 177-STRUCT-1
             role: CarrierRole::LoopState, // Phase 227: Default to LoopState
+            init: CarrierInit::FromHost, // Phase 228: Default to FromHost
         }
     }
 

src/mir/join_ir/lowering/carrier_update_emitter.rs

@@ -422,6 +422,7 @@ mod tests {
             host_id: ValueId(host_id),
             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
         }
     }
 

src/mir/join_ir/lowering/inline_boundary.rs

@@ -246,6 +246,16 @@ pub struct JoinInlineBoundary {
     /// The name of the loop control variable (e.g., "i" in `loop(i < 3)`).
     /// Used to track which PHI corresponds to the loop variable.
     pub loop_var_name: Option<String>,
+
+    /// Phase 228: Carrier metadata (for header PHI generation)
+    ///
+    /// Contains full carrier information including initialization policies.
+    /// This allows header PHI generation to handle ConditionOnly carriers
+    /// with explicit bool initialization.
+    ///
+    /// - `Some(CarrierInfo)`: Full carrier metadata available
+    /// - `None`: Legacy path (derive carriers from exit_bindings)
+    pub carrier_info: Option<super::carrier_info::CarrierInfo>,
 }
 
 impl JoinInlineBoundary {
@@ -272,6 +282,7 @@ impl JoinInlineBoundary {
             condition_bindings: vec![], // Phase 171-fix: Default to empty
             expr_result: None, // Phase 33-14: Default to carrier-only pattern
             loop_var_name: None, // Phase 33-16
+            carrier_info: None, // Phase 228: Default to None
         }
     }
 
@@ -314,6 +325,7 @@ impl JoinInlineBoundary {
             condition_bindings: vec![], // Phase 171-fix: Default to empty
             expr_result: None, // Phase 33-14
             loop_var_name: None, // Phase 33-16
+            carrier_info: None, // Phase 228
         }
     }
 
@@ -373,6 +385,7 @@ impl JoinInlineBoundary {
             condition_bindings: vec![], // Phase 171-fix: Default to empty
             expr_result: None, // Phase 33-14
             loop_var_name: None, // Phase 33-16
+            carrier_info: None, // Phase 228
         }
     }
 
@@ -418,6 +431,7 @@ impl JoinInlineBoundary {
             condition_bindings: vec![], // Phase 171-fix: Will be populated by new constructor
             expr_result: None, // Phase 33-14
             loop_var_name: None, // Phase 33-16
+            carrier_info: None, // Phase 228
         }
     }
 
@@ -467,6 +481,7 @@ impl JoinInlineBoundary {
             condition_bindings: vec![], // Phase 171-fix: Will be populated by new constructor
             expr_result: None, // Phase 33-14
             loop_var_name: None, // Phase 33-16
+            carrier_info: None, // Phase 228
         }
     }
 
@@ -523,6 +538,7 @@ impl JoinInlineBoundary {
             condition_bindings,
             expr_result: None, // Phase 33-14
             loop_var_name: None, // Phase 33-16
+            carrier_info: None, // Phase 228
         }
     }
 }

src/mir/join_ir/lowering/inline_boundary_builder.rs

@@ -27,7 +27,7 @@
 use crate::mir::ValueId;
 use super::inline_boundary::{JoinInlineBoundary, LoopExitBinding};
 use super::condition_to_joinir::ConditionBinding;
-use super::carrier_info::CarrierRole;
+use super::carrier_info::CarrierRole; // Phase 228: Restored for test code
 
 /// Role of a parameter in JoinIR lowering (Phase 200-A)
 ///
@@ -96,6 +96,7 @@ impl JoinInlineBoundaryBuilder {
                 condition_bindings: vec![],
                 expr_result: None,
                 loop_var_name: None,
+                carrier_info: None, // Phase 228: Initialize as None
             }
         }
     }
@@ -261,6 +262,29 @@ impl JoinInlineBoundaryBuilder {
             .find(|b| b.name == name)
             .map(|b| b.join_value)
     }
+
+    /// Phase 228: Set carrier metadata
+    ///
+    /// Provides full carrier information including initialization policies.
+    /// This allows header PHI generation to handle ConditionOnly carriers
+    /// with explicit bool initialization.
+    ///
+    /// # Arguments
+    ///
+    /// * `carrier_info` - Complete carrier metadata from pattern lowerer
+    ///
+    /// # Example
+    ///
+    /// ```ignore
+    /// let boundary = JoinInlineBoundaryBuilder::new()
+    ///     .with_inputs(join_inputs, host_inputs)
+    ///     .with_carrier_info(ctx.carrier_info.clone())
+    ///     .build();
+    /// ```
+    pub fn with_carrier_info(mut self, carrier_info: super::carrier_info::CarrierInfo) -> Self {
+        self.boundary.carrier_info = Some(carrier_info);
+        self
+    }
 }
 
 impl Default for JoinInlineBoundaryBuilder {

src/mir/join_ir/lowering/loop_update_analyzer.rs

@@ -299,6 +299,7 @@ mod tests {
             host_id: crate::mir::ValueId(0),
             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
         }];
 
         let updates = LoopUpdateAnalyzer::analyze_carrier_updates(&body, &carriers);
@@ -357,6 +358,7 @@ mod tests {
             host_id: crate::mir::ValueId(0),
             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
         }];
 
         let updates = LoopUpdateAnalyzer::analyze_carrier_updates(&body, &carriers);
@@ -416,6 +418,7 @@ mod tests {
             host_id: crate::mir::ValueId(0),
             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
         }];
 
         let updates = LoopUpdateAnalyzer::analyze_carrier_updates(&body, &carriers);
@@ -475,6 +478,7 @@ mod tests {
             host_id: crate::mir::ValueId(0),
             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
         }];
 
         let updates = LoopUpdateAnalyzer::analyze_carrier_updates(&body, &carriers);

src/mir/loop_pattern_detection/loop_body_digitpos_promoter.rs

@@ -183,12 +183,13 @@ impl DigitPosPromoter {
                 // For DigitPos pattern, we add a NEW carrier (not replace loop_var)
                 let carrier_name = format!("is_{}", var_in_cond);
 
-                use crate::mir::join_ir::lowering::carrier_info::{CarrierVar, CarrierRole};
+                use crate::mir::join_ir::lowering::carrier_info::{CarrierVar, CarrierRole, CarrierInit};
                 let promoted_carrier = CarrierVar {
                     name: carrier_name.clone(),
                     host_id: ValueId(0), // Placeholder (will be remapped)
                     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
                 };
 
                 // Create CarrierInfo with a dummy loop_var_name (will be ignored during merge)