diff --git a/src/mir/builder/control_flow/joinir/patterns/pattern1_minimal.rs b/src/mir/builder/control_flow/joinir/patterns/pattern1_minimal.rs
index 0ec51b72..e1942fd9 100644
--- a/src/mir/builder/control_flow/joinir/patterns/pattern1_minimal.rs
+++ b/src/mir/builder/control_flow/joinir/patterns/pattern1_minimal.rs
@@ -28,6 +28,7 @@ pub fn lower(
 
 impl MirBuilder {
     /// Phase 179-B: Pattern 1 (Simple While Loop) minimal lowerer
+    /// Phase 202-A: JoinValueSpace Integration
     ///
     /// **Refactored**: Now uses PatternPipelineContext for unified preprocessing
     ///
@@ -60,8 +61,13 @@ impl MirBuilder {
         // Phase 195: Use unified trace
         trace::trace().varmap("pattern1_start", &self.variable_map);
 
+        // Phase 202-A: Create JoinValueSpace for unified ValueId allocation
+        // Pattern 1 uses Local region only (no Param region needed - no ConditionEnv)
+        use crate::mir::join_ir::lowering::join_value_space::JoinValueSpace;
+        let mut join_value_space = JoinValueSpace::new();
+
         // Call Pattern 1 lowerer with preprocessed scope
-        let join_module = match lower_simple_while_minimal(ctx.loop_scope) {
+        let join_module = match lower_simple_while_minimal(ctx.loop_scope, &mut join_value_space) {
             Some(module) => module,
             None => {
                 // Phase 195: Use unified trace
diff --git a/src/mir/join_ir/lowering/loop_view_builder.rs b/src/mir/join_ir/lowering/loop_view_builder.rs
index d2b99391..802887e2 100644
--- a/src/mir/join_ir/lowering/loop_view_builder.rs
+++ b/src/mir/join_ir/lowering/loop_view_builder.rs
@@ -118,6 +118,8 @@ impl LoopViewBuilder {
     /// - 関数名に "main" が含まれる
     /// - Pinned vars がない
     /// - Carriers が1つ以上
+    ///
+    /// # Phase 202-A: JoinValueSpace Integration
     fn try_pattern1(&self, scope: &LoopScopeShape, name: &str) -> Option<JoinModule> {
         if !name.contains("main") {
             return None;
@@ -128,7 +130,14 @@ impl LoopViewBuilder {
                 eprintln!("[LoopViewBuilder] Trying Pattern 1 lowering for {:?}", name);
             }
 
-            if let Some(result) = super::simple_while_minimal::lower_simple_while_minimal(scope.clone()) {
+            // Phase 202-A: Create JoinValueSpace for Pattern 1
+            use super::join_value_space::JoinValueSpace;
+            let mut join_value_space = JoinValueSpace::new();
+
+            if let Some(result) = super::simple_while_minimal::lower_simple_while_minimal(
+                scope.clone(),
+                &mut join_value_space,
+            ) {
                 if self.debug {
                     eprintln!("[LoopViewBuilder] Pattern 1 lowering succeeded for {:?}", name);
                 }
diff --git a/src/mir/join_ir/lowering/simple_while_minimal.rs b/src/mir/join_ir/lowering/simple_while_minimal.rs
index 0dff1d78..c7804688 100644
--- a/src/mir/join_ir/lowering/simple_while_minimal.rs
+++ b/src/mir/join_ir/lowering/simple_while_minimal.rs
@@ -42,21 +42,21 @@
 //!
 //! Following the "80/20 rule" from CLAUDE.md - get it working first, generalize later.
 
+use crate::mir::join_ir::lowering::join_value_space::JoinValueSpace;
 use crate::mir::join_ir::lowering::loop_scope_shape::LoopScopeShape;
 use crate::mir::join_ir::{
     BinOpKind, CompareOp, ConstValue, JoinFuncId, JoinFunction, JoinInst, JoinModule,
     MirLikeInst, UnaryOp,
 };
-use crate::mir::ValueId;
 
 
 /// Lower Pattern 1 (Simple While Loop) to JoinIR
 ///
 /// # Phase 188-Impl-3: Pure JoinIR Fragment Generation
+/// # Phase 202-A: JoinValueSpace Integration
 ///
-/// This version generates JoinIR using **local ValueIds only** (0, 1, 2, ...).
-/// It has NO knowledge of the host function's ValueId space. The boundary mapping
-/// is handled separately via JoinInlineBoundary.
+/// This version generates JoinIR using **JoinValueSpace** for unified ValueId allocation.
+/// It uses the Local region (1000+) to avoid collision with Param region (100-999).
 ///
 /// ## Design Philosophy
 ///
@@ -73,6 +73,7 @@ use crate::mir::ValueId;
 /// # Arguments
 ///
 /// * `_scope` - LoopScopeShape (reserved for future generic implementation)
+/// * `join_value_space` - Unified ValueId allocator (Phase 202-A)
 ///
 /// # Returns
 ///
@@ -84,15 +85,13 @@ use crate::mir::ValueId;
 /// This function returns a JoinModule with:
 /// - **Input slot**: ValueId(0) in loop_step function represents the loop variable
 /// - **Caller responsibility**: Create JoinInlineBoundary to map ValueId(0) to host's loop var
-pub(crate) fn lower_simple_while_minimal(_scope: LoopScopeShape) -> Option<JoinModule> {
-    // Phase 188-Impl-3: Use local ValueId allocator (sequential from 0)
-    // JoinIR has NO knowledge of host ValueIds - boundary handled separately
-    let mut value_counter = 0u32;
-    let mut alloc_value = || {
-        let id = ValueId(value_counter);
-        value_counter += 1;
-        id
-    };
+pub(crate) fn lower_simple_while_minimal(
+    _scope: LoopScopeShape,
+    join_value_space: &mut JoinValueSpace,
+) -> Option<JoinModule> {
+    // Phase 202-A: Use JoinValueSpace for Local region allocation (1000+)
+    // This ensures no collision with Param region (100-999) used by ConditionEnv/CarrierInfo
+    let mut alloc_value = || join_value_space.alloc_local();
 
     let mut join_module = JoinModule::new();