diff --git a/crates/oxide_ir/src/contract.rs b/crates/oxide_ir/src/contract.rs
new file mode 100644
index 00000000..81d46c4f
--- /dev/null
+++ b/crates/oxide_ir/src/contract.rs
@@ -0,0 +1,585 @@
+//! Inst 寄存器契约：def/use 扫描 + 副作用判定（DCE 与 Phase 5 liveness 共用，D-06）。
+//!
+//! `def_reg` / `use_regs` / `is_pure` 是 `Inst` 的类型契约方法（`impl Inst` 与 `inst.rs`
+//! 中的构造 API 同属一类型），落在 oxide_ir 契约层供 DCE 消费、liveness 复用。
+//! 寄存器规则逐条对照 VM dispatch handler（RESEARCH Pattern 1/2 全表）：
+//! CALL 隐式写 reg 0、GET_PROP 结果写 a/b 槽、HALT 隐式读 reg 0、None 槽映射 Reg(0)。
+
+use oxide_bytecode::opcode::OpCode;
+use smallvec::SmallVec;
+
+use crate::inst::Inst;
+use crate::operand::Operand;
+use crate::IRFunction;
+
+impl Inst {
+    /// 本指令定义的寄存器（None 槽按 Reg(0) 映射；CALL 系含隐式 reg 0）。
+    /// 无写入返回 None。
+    pub fn def_reg(&self) -> Option<u32> {
+        match self.op {
+            // CALL 系：结果隐式写 reg 0，rd 是 callee use（Pitfall 1）
+            OpCode::CALL | OpCode::CALL_NATIVE => Some(0),
+            // GET_PROP 系：结果写 a/b 槽而非 rd（Pitfall 3）
+            OpCode::GET_PROP | OpCode::IC_GET_PROP => reg_of(&self.a),
+            OpCode::GET_PROP_DYNAMIC => reg_of(&self.b),
+            // 成员读写：val 槽原地更新（a 槽 / b 槽）
+            OpCode::MEMBER_INC | OpCode::MEMBER_DEC => reg_of(&self.a),
+            OpCode::DYN_MEMBER_INC | OpCode::DYN_MEMBER_DEC => reg_of(&self.b),
+            OpCode::COMPOUND_MEMBER_ADD
+            | OpCode::COMPOUND_MEMBER_SUB
+            | OpCode::COMPOUND_MEMBER_MUL
+            | OpCode::COMPOUND_MEMBER_DIV
+            | OpCode::COMPOUND_MEMBER_MOD
+            | OpCode::COMPOUND_MEMBER_EXP => reg_of(&self.a),
+            // 无 def：控制流 / 写共享状态 / 纯写对象
+            OpCode::HALT
+            | OpCode::RETURN
+            | OpCode::THROW
+            | OpCode::JMP
+            | OpCode::JMP_IF_FALSE
+            | OpCode::JMP_IF_TRUE
+            | OpCode::JMP_IF_NULLISH
+            | OpCode::TRY_BEGIN
+            | OpCode::TRY_END
+            | OpCode::TRY_FINALLY_BEGIN
+            | OpCode::TRY_FINALLY_END
+            | OpCode::MAKE_CELL
+            | OpCode::CELL_SET
+            | OpCode::STORE_UPVALUE
+            | OpCode::SET_PROP
+            | OpCode::SET_PROP_DYNAMIC
+            | OpCode::IC_SET_PROP
+            | OpCode::SET_ELEM
+            | OpCode::GET_PRIVATE
+            | OpCode::SET_PRIVATE
+            | OpCode::INIT_PRIVATE
+            | OpCode::PRIVATE_BRAND_IN
+            | OpCode::DELETE_PROP_STATIC
+            | OpCode::DELETE_PROP_DYNAMIC
+            | OpCode::DEFINE_ACCESSOR
+            | OpCode::SET_HOME_OBJECT
+            | OpCode::FOR_IN_INIT
+            | OpCode::FOR_OF_INIT
+            | OpCode::FOR_IN_CLEANUP
+            | OpCode::FOR_OF_CLOSE => None,
+            // 其余指令 rd 即 def（算术/比较/位/逻辑/加载族/迭代器 NEXT 等）
+            _ => reg_of(&self.rd),
+        }
+    }
+
+    /// 本指令读取的寄存器（None 槽按 Reg(0) 映射；HALT 特判 reg 0；TEMPLATE_STR 解析 ext）。
+    pub fn use_regs(&self) -> SmallVec<[u32; 4]> {
+        let mut uses = SmallVec::new();
+        match self.op {
+            // CALL 系：rd=callee, a=this, b..b+nargs 参数区间（Pitfall 1）
+            OpCode::CALL | OpCode::CALL_NATIVE => {
+                push_operand(&mut uses, &self.rd);
+                push_operand(&mut uses, &self.a);
+                let nargs = self.ext.first().copied().unwrap_or(0);
+                push_range(&mut uses, reg_of(&self.b), nargs);
+            }
+            // NEW_EXPRESSION：a=ctor, b..b+nargs
+            OpCode::NEW_EXPRESSION => {
+                push_operand(&mut uses, &self.a);
+                let nargs = self.ext.first().copied().unwrap_or(0);
+                push_range(&mut uses, reg_of(&self.b), nargs);
+            }
+            // SUPER_CALL：a..a+nargs
+            OpCode::SUPER_CALL => {
+                let nargs = self.ext.first().copied().unwrap_or(0);
+                push_range(&mut uses, reg_of(&self.a), nargs);
+            }
+            // GET_PROP 系：结果写 a/b 槽，rd=obj 是 use（Pitfall 3）
+            OpCode::GET_PROP => {
+                push_operand(&mut uses, &self.rd);
+                push_operand(&mut uses, &self.b);
+            }
+            OpCode::GET_PROP_DYNAMIC => {
+                push_operand(&mut uses, &self.rd);
+                push_operand(&mut uses, &self.a);
+            }
+            OpCode::IC_GET_PROP => {
+                push_operand(&mut uses, &self.a);
+                push_operand(&mut uses, &self.b);
+            }
+            // 成员更新：obj + key 是 use，val 槽是 def
+            OpCode::MEMBER_INC | OpCode::MEMBER_DEC => {
+                push_operand(&mut uses, &self.rd);
+                push_operand(&mut uses, &self.b);
+            }
+            OpCode::DYN_MEMBER_INC | OpCode::DYN_MEMBER_DEC => {
+                push_operand(&mut uses, &self.rd);
+                push_operand(&mut uses, &self.a);
+            }
+            OpCode::COMPOUND_MEMBER_ADD
+            | OpCode::COMPOUND_MEMBER_SUB
+            | OpCode::COMPOUND_MEMBER_MUL
+            | OpCode::COMPOUND_MEMBER_DIV
+            | OpCode::COMPOUND_MEMBER_MOD
+            | OpCode::COMPOUND_MEMBER_EXP => {
+                push_operand(&mut uses, &self.rd);
+                push_operand(&mut uses, &self.a);
+                push_operand(&mut uses, &self.b);
+            }
+            // 复合赋值：rd 与 a 都是 use（coerce 读双寄存器）
+            OpCode::COMPOUND_ADD
+            | OpCode::COMPOUND_SUB
+            | OpCode::COMPOUND_MUL
+            | OpCode::COMPOUND_DIV
+            | OpCode::COMPOUND_MOD
+            | OpCode::COMPOUND_EXP
+            | OpCode::COMPOUND_AND
+            | OpCode::COMPOUND_OR
+            | OpCode::COMPOUND_XOR
+            | OpCode::COMPOUND_SHL
+            | OpCode::COMPOUND_SHR
+            | OpCode::COMPOUND_USHR => {
+                push_operand(&mut uses, &self.rd);
+                push_operand(&mut uses, &self.a);
+            }
+            // 自增/自减：读 rd（写 rd 和 a）
+            OpCode::INC_PRE | OpCode::INC_POST | OpCode::DEC_PRE | OpCode::DEC_POST => {
+                push_operand(&mut uses, &self.rd);
+            }
+            // 二元运算：a, b
+            OpCode::ADD | OpCode::SUB | OpCode::MUL | OpCode::DIV | OpCode::MOD | OpCode::EQ
+            | OpCode::NEQ | OpCode::LT | OpCode::GT | OpCode::LTE | OpCode::GTE | OpCode::AND
+            | OpCode::OR | OpCode::NULLISH | OpCode::STRICT_EQ | OpCode::STRICT_NEQ
+            | OpCode::BIT_AND | OpCode::BIT_OR | OpCode::BIT_XOR | OpCode::SHL | OpCode::SHR
+            | OpCode::USHR | OpCode::INSTANCEOF | OpCode::IN | OpCode::CREATE_REGEXP => {
+                push_operand(&mut uses, &self.a);
+                push_operand(&mut uses, &self.b);
+            }
+            // 一元：a（emit 常 rd==a）
+            OpCode::NEG | OpCode::NOT | OpCode::UNARY_PLUS | OpCode::BIT_NOT | OpCode::TYPEOF => {
+                push_operand(&mut uses, &self.a);
+            }
+            // 无条件跳转 / try 标记：b 是 Label，无寄存器
+            OpCode::JMP | OpCode::TRY_BEGIN | OpCode::TRY_FINALLY_BEGIN | OpCode::TRY_END
+            | OpCode::TRY_FINALLY_END | OpCode::FOR_IN_CLEANUP | OpCode::FOR_OF_CLOSE => {}
+            // 条件跳转：rd=cond
+            OpCode::JMP_IF_FALSE | OpCode::JMP_IF_TRUE | OpCode::JMP_IF_NULLISH => {
+                push_operand(&mut uses, &self.rd);
+            }
+            // HALT：隐式读 reg 0（顶层返回值，Pitfall 2）
+            OpCode::HALT => uses.push(0),
+            // RETURN/THROW：读 rd（None→0）
+            OpCode::RETURN | OpCode::THROW => push_operand(&mut uses, &self.rd),
+            // 加载族：a 槽是 Const/Imm 立即数，无寄存器 use
+            OpCode::LOAD_CONST | OpCode::CREATE_CLOSURE | OpCode::LOAD_UPVALUE | OpCode::VOID
+            | OpCode::NEW_OBJECT | OpCode::NEW_ARRAY | OpCode::NOP => {}
+            // 变量读写：LOAD_VAR/STORE_VAR/CELL_GET 读 a（None→0）
+            OpCode::LOAD_VAR | OpCode::STORE_VAR | OpCode::CELL_GET => {
+                push_operand(&mut uses, &self.a);
+            }
+            // MAKE_CELL：cell 初值读 rd；CELL_SET/STORE_UPVALUE 读 a
+            OpCode::MAKE_CELL => push_operand(&mut uses, &self.rd),
+            OpCode::CELL_SET | OpCode::STORE_UPVALUE => push_operand(&mut uses, &self.a),
+            // 写对象属性：rd/a/b 全 use
+            OpCode::SET_PROP | OpCode::SET_PROP_DYNAMIC | OpCode::IC_SET_PROP | OpCode::SET_ELEM
+            | OpCode::GET_PRIVATE | OpCode::SET_PRIVATE | OpCode::INIT_PRIVATE
+            | OpCode::PRIVATE_BRAND_IN | OpCode::DEFINE_ACCESSOR => {
+                push_operand(&mut uses, &self.rd);
+                push_operand(&mut uses, &self.a);
+                push_operand(&mut uses, &self.b);
+            }
+            // delete：读 obj（+dynamic 读 key）
+            OpCode::DELETE_PROP_STATIC => push_operand(&mut uses, &self.rd),
+            OpCode::DELETE_PROP_DYNAMIC => {
+                push_operand(&mut uses, &self.rd);
+                push_operand(&mut uses, &self.b);
+            }
+            // super 属性读：a=this, b=key
+            OpCode::SUPER_GET_PROP | OpCode::SUPER_STATIC_GET_PROP => {
+                push_operand(&mut uses, &self.a);
+                push_operand(&mut uses, &self.b);
+            }
+            // SET_HOME_OBJECT：rd=func, a=home
+            OpCode::SET_HOME_OBJECT => {
+                push_operand(&mut uses, &self.rd);
+                push_operand(&mut uses, &self.a);
+            }
+            // for-in/of 迭代器：INIT 读 a；NEXT/DONE 读迭代器栈隐式状态
+            OpCode::FOR_IN_INIT | OpCode::FOR_OF_INIT => push_operand(&mut uses, &self.a),
+            OpCode::FOR_IN_NEXT | OpCode::FOR_IN_DONE | OpCode::FOR_OF_NEXT | OpCode::FOR_OF_DONE => {}
+            // REST_OBJECT：读 a（ext 是 excluded_idx 常量）
+            OpCode::REST_OBJECT => push_operand(&mut uses, &self.a),
+            // TEMPLATE_STR：解析 ext，跳过 ext[0]，后续 seg>>31==1 则低 8 位是 expr_reg（A1）
+            OpCode::TEMPLATE_STR => {
+                for seg in self.ext.iter().skip(1) {
+                    if seg >> 31 == 1 {
+                        uses.push(seg & 0xFF);
+                    }
+                }
+            }
+            // 占位 opcode（emit 不产）：按无 use 保守处理，不影响合法产物
+            OpCode::SWITCH_TABLE | OpCode::PROFILE_TYPE | OpCode::PROFILE_SHAPE
+            | OpCode::PROFILE_BRANCH | OpCode::PROFILE_CALL | OpCode::FORK | OpCode::JOIN => {}
+        }
+        uses
+    }
+
+    /// 本指令是否无观察副作用（Pattern 1 纯表；LOAD_VAR 的 This+derived 特判需 &IRFunction）。
+    ///
+    /// 纯 = 结果未用时可删。表外 opcode 一律有副作用（D-05 精确表，宁少删不错删）。
+    pub fn is_pure(&self, f: &IRFunction) -> bool {
+        match self.op {
+            // 算术 / 比较 / 位 / 逻辑：coerce 对象路径有抛错风险，D-05 决策算纯（运行时等价兜底）
+            OpCode::ADD | OpCode::SUB | OpCode::MUL | OpCode::DIV | OpCode::MOD | OpCode::NEG
+            | OpCode::UNARY_PLUS | OpCode::EQ | OpCode::NEQ | OpCode::LT | OpCode::GT
+            | OpCode::LTE | OpCode::GTE | OpCode::STRICT_EQ | OpCode::STRICT_NEQ
+            | OpCode::BIT_AND | OpCode::BIT_OR | OpCode::BIT_XOR | OpCode::SHL | OpCode::SHR
+            | OpCode::USHR | OpCode::BIT_NOT | OpCode::AND | OpCode::OR | OpCode::NOT
+            | OpCode::NULLISH => true,
+            // 分配 / 常量 / 空操作（a 槽非寄存器）
+            OpCode::NOP | OpCode::LOAD_CONST | OpCode::VOID | OpCode::TYPEOF | OpCode::NEW_OBJECT
+            | OpCode::NEW_ARRAY => true,
+            // 闭包 / cell 读取：无抛错路径（D-07）
+            OpCode::CREATE_CLOSURE | OpCode::LOAD_UPVALUE | OpCode::CELL_GET => true,
+            // 模板字符串：纯拼接写 rd，无抛错（use 统计覆盖其 ext）
+            OpCode::TEMPLATE_STR => true,
+            // LOAD_VAR：仅 a==This 且 derived 构造函数读 this 可能抛 ReferenceError（misc.rs:52-63）
+            OpCode::LOAD_VAR => {
+                !(self.a == Operand::This && f.is_derived_constructor)
+            }
+            // STORE_VAR：写变量目标寄存器。脚本顶层/模块作用域的变量是**全局可观察状态**
+            // （Pitfall 6：`let x=0; class C{[x=1](){}}` 无后续本地读取时删除 `x=1` 会改变
+            // 外部 `assert(x===1)` 的观察结果）；函数内局部未用赋值的优化留给 Phase 5 精确活度。
+            OpCode::STORE_VAR => false,
+            // 其余全部有副作用（getter/调用/控制流/迭代器/复合更新/写共享状态/占位防御）
+            _ => false,
+        }
+    }
+}
+
+/// 操作数 → 物理寄存器号。None 槽映射 reg 0（A3，与 lower.rs operand_to_u8 一致）；
+/// Const/Imm/Label 不是寄存器槽，返回 None。
+fn reg_of(o: &Operand) -> Option<u32> {
+    match o {
+        Operand::Reg(r) => Some(*r),
+        Operand::This => Some(254),
+        Operand::NewTarget => Some(255),
+        Operand::None => Some(0),
+        Operand::Const(_) | Operand::Imm(_) | Operand::Label(_) => None,
+    }
+}
+
+/// 把寄存器操作数推入 use 集合（非寄存器槽跳过）。
+fn push_operand(uses: &mut SmallVec<[u32; 4]>, o: &Operand) {
+    if let Some(r) = reg_of(o) {
+        uses.push(r);
+    }
+}
+
+/// 推入连续参数区间 [first, first+nargs)。
+fn push_range(uses: &mut SmallVec<[u32; 4]>, first: Option<u32>, nargs: u32) {
+    if let Some(f) = first {
+        uses.extend((0..nargs).map(|i| f + i));
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::inst::Inst;
+    use crate::operand::Operand;
+    use crate::IRFunction;
+
+    // ── def_reg / use_regs 契约测试（Pattern 2 全表，反直觉槽位锁定）──
+
+    #[test]
+    fn binary_op_def_rd_use_ab() {
+        let inst = Inst::new(OpCode::ADD, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2));
+        assert_eq!(inst.def_reg(), Some(0));
+        assert_eq!(inst.use_regs().as_slice(), &[1, 2]);
+    }
+
+    #[test]
+    fn unary_op_def_rd_use_a() {
+        let inst = Inst::new(OpCode::NEG, Operand::Reg(0), Operand::Reg(1), Operand::None);
+        assert_eq!(inst.def_reg(), Some(0));
+        assert_eq!(inst.use_regs().as_slice(), &[1]);
+    }
+
+    #[test]
+    fn get_prop_def_is_a_slot_not_rd() {
+        // Pitfall 3：GET_PROP rd=obj 是 use，结果写 a 槽
+        let inst = Inst::new(OpCode::GET_PROP, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2));
+        assert_eq!(inst.def_reg(), Some(1));
+        assert_eq!(inst.use_regs().as_slice(), &[0, 2]);
+    }
+
+    #[test]
+    fn get_prop_dynamic_def_is_b_slot() {
+        // Pitfall 3：GET_PROP_DYNAMIC rd=obj 是 use，结果写 b 槽
+        let inst = Inst::new(OpCode::GET_PROP_DYNAMIC, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2));
+        assert_eq!(inst.def_reg(), Some(2));
+        assert_eq!(inst.use_regs().as_slice(), &[0, 1]);
+    }
+
+    #[test]
+    fn ic_get_prop_a_slot_is_use_and_def() {
+        // Pitfall 3：IC_GET_PROP a 槽既是对象 use 又是结果 def
+        let inst = Inst::ic_get(Operand::Reg(1), Operand::Reg(2));
+        assert_eq!(inst.def_reg(), Some(1));
+        let uses = inst.use_regs();
+        assert_eq!(uses.as_slice(), &[1, 2]);
+    }
+
+    #[test]
+    fn call_def_is_implicit_reg0_with_arg_range() {
+        // Pitfall 1：CALL rd=callee 是 use，结果隐式写 reg 0；参数 b..b+nargs 连续
+        let inst = Inst::call(Operand::Reg(0), Operand::Reg(1), Operand::Reg(2), 3);
+        assert_eq!(inst.def_reg(), Some(0));
+        assert_eq!(inst.use_regs().as_slice(), &[0, 1, 2, 3, 4]);
+    }
+
+    #[test]
+    fn call_native_def_is_implicit_reg0() {
+        let inst = Inst::call_native(Operand::Reg(0), Operand::Reg(1), Operand::Reg(2), 1);
+        assert_eq!(inst.def_reg(), Some(0));
+        assert_eq!(inst.use_regs().as_slice(), &[0, 1, 2]);
+    }
+
+    #[test]
+    fn new_expression_uses_ctor_and_arg_range() {
+        let inst = Inst::new_expression(Operand::Reg(3), Operand::Reg(0), Operand::Reg(1), 2);
+        assert_eq!(inst.def_reg(), Some(3));
+        assert_eq!(inst.use_regs().as_slice(), &[0, 1, 2]);
+    }
+
+    #[test]
+    fn super_call_uses_arg_range() {
+        let inst = Inst::super_call(Operand::Reg(3), Operand::Reg(1), 1);
+        assert_eq!(inst.def_reg(), Some(3));
+        assert_eq!(inst.use_regs().as_slice(), &[1]);
+    }
+
+    #[test]
+    fn halt_implicitly_uses_reg0() {
+        // Pitfall 2：HALT 返回 regs[0]，顶层 LOAD_VAR(None, r) 链靠它保活
+        let inst = Inst::new(OpCode::HALT, Operand::None, Operand::None, Operand::None);
+        assert_eq!(inst.def_reg(), None);
+        assert_eq!(inst.use_regs().as_slice(), &[0]);
+    }
+
+    #[test]
+    fn void_defs_rd_no_use() {
+        // VM 的 VOID handler 不读 a 槽
+        let inst = Inst::new(OpCode::VOID, Operand::Reg(1), Operand::Reg(2), Operand::None);
+        assert_eq!(inst.def_reg(), Some(1));
+        assert!(inst.use_regs().is_empty());
+    }
+
+    #[test]
+    fn load_const_create_closure_load_upvalue_no_use() {
+        // a 槽是 Const/Imm 立即数，非寄存器
+        let lc = Inst::load_const(Operand::Reg(1), 5);
+        assert_eq!(lc.def_reg(), Some(1));
+        assert!(lc.use_regs().is_empty());
+
+        let cc = Inst::create_closure(Operand::Reg(1), 0);
+        assert_eq!(cc.def_reg(), Some(1));
+        assert!(cc.use_regs().is_empty());
+
+        let lu = Inst::new(OpCode::LOAD_UPVALUE, Operand::Reg(1), Operand::Imm(0), Operand::None);
+        assert_eq!(lu.def_reg(), Some(1));
+        assert!(lu.use_regs().is_empty());
+    }
+
+    #[test]
+    fn none_slot_maps_to_reg0() {
+        // A3：None 槽与 lower.rs operand_to_u8 一致，统一映射物理 reg 0
+        let lv = Inst::new(OpCode::LOAD_VAR, Operand::Reg(1), Operand::None, Operand::None);
+        assert_eq!(lv.use_regs().as_slice(), &[0]);
+
+        let cg = Inst::new(OpCode::CELL_GET, Operand::Reg(0), Operand::None, Operand::Imm(0));
+        assert_eq!(cg.use_regs().as_slice(), &[0]);
+    }
+
+    #[test]
+    fn template_str_parses_expr_regs_from_ext() {
+        // ext[0] 跳过；后续 seg>>31==1 则低 8 位是 expr_reg（A1，emit 8 位编码）
+        let with_expr = Inst::template_str(Operand::Reg(1), 2, 10, &[0x1234, 0x8000_0000 | 5]);
+        assert_eq!(with_expr.use_regs().as_slice(), &[5]);
+
+        // 纯 quasi（无表达式）：不误报寄存器
+        let no_expr = Inst::template_str(Operand::Reg(1), 1, 10, &[0x1234]);
+        assert!(no_expr.use_regs().is_empty());
+    }
+
+    #[test]
+    fn jmp_if_false_uses_cond_reg() {
+        let inst = Inst::jmp_if_false(3, 9);
+        assert_eq!(inst.def_reg(), None);
+        assert_eq!(inst.use_regs().as_slice(), &[3]);
+    }
+
+    #[test]
+    fn jmp_and_try_no_use() {
+        assert!(Inst::jmp(9).use_regs().is_empty());
+        assert!(Inst::try_begin(9).use_regs().is_empty());
+        assert!(Inst::try_finally_begin(9).use_regs().is_empty());
+    }
+
+    #[test]
+    fn make_cell_no_def_uses_rd() {
+        let inst = Inst::new(OpCode::MAKE_CELL, Operand::Reg(5), Operand::None, Operand::None);
+        assert_eq!(inst.def_reg(), None);
+        assert_eq!(inst.use_regs().as_slice(), &[5]);
+    }
+
+    #[test]
+    fn cell_set_and_store_upvalue_use_a_no_def() {
+        let cs = Inst::new(OpCode::CELL_SET, Operand::None, Operand::Reg(1), Operand::Imm(0));
+        assert_eq!(cs.def_reg(), None);
+        assert_eq!(cs.use_regs().as_slice(), &[1]);
+
+        let su = Inst::new(OpCode::STORE_UPVALUE, Operand::None, Operand::Reg(1), Operand::Imm(0));
+        assert_eq!(su.def_reg(), None);
+        assert_eq!(su.use_regs().as_slice(), &[1]);
+    }
+
+    #[test]
+    fn return_throw_use_rd_with_none_mapping_reg0() {
+        let ret = Inst::new(OpCode::RETURN, Operand::None, Operand::None, Operand::None);
+        assert_eq!(ret.def_reg(), None);
+        assert_eq!(ret.use_regs().as_slice(), &[0]);
+
+        let thr = Inst::new(OpCode::THROW, Operand::Reg(2), Operand::None, Operand::None);
+        assert_eq!(thr.def_reg(), None);
+        assert_eq!(thr.use_regs().as_slice(), &[2]);
+    }
+
+    #[test]
+    fn rest_object_uses_a() {
+        let inst = Inst::rest_object(Operand::Reg(0), Operand::Reg(1), 7);
+        assert_eq!(inst.def_reg(), Some(0));
+        assert_eq!(inst.use_regs().as_slice(), &[1]);
+    }
+
+    #[test]
+    fn for_in_next_defs_rd_no_use() {
+        let inst = Inst::new(OpCode::FOR_IN_NEXT, Operand::Reg(0), Operand::None, Operand::None);
+        assert_eq!(inst.def_reg(), Some(0));
+        assert!(inst.use_regs().is_empty());
+    }
+
+    #[test]
+    fn store_var_def_rd_use_a() {
+        let inst = Inst::new(OpCode::STORE_VAR, Operand::Reg(0), Operand::Reg(1), Operand::None);
+        assert_eq!(inst.def_reg(), Some(0));
+        assert_eq!(inst.use_regs().as_slice(), &[1]);
+    }
+
+    // ── is_pure 契约测试（Pattern 1 表，纯/非纯族代表 opcode）──
+
+    #[test]
+    fn pure_ops_are_deletable() {
+        let f = IRFunction::new();
+        // 算术 / 比较 / 位 / 逻辑
+        assert!(Inst::new(OpCode::ADD, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
+        assert!(Inst::new(OpCode::SUB, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
+        assert!(Inst::new(OpCode::MUL, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
+        assert!(Inst::new(OpCode::NEG, Operand::Reg(0), Operand::Reg(1), Operand::None).is_pure(&f));
+        assert!(Inst::new(OpCode::EQ, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
+        assert!(Inst::new(OpCode::STRICT_EQ, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
+        assert!(Inst::new(OpCode::LT, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
+        assert!(Inst::new(OpCode::BIT_AND, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
+        assert!(Inst::new(OpCode::BIT_NOT, Operand::Reg(0), Operand::Reg(1), Operand::None).is_pure(&f));
+        assert!(Inst::new(OpCode::AND, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
+        assert!(Inst::new(OpCode::OR, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
+        assert!(Inst::new(OpCode::NOT, Operand::Reg(0), Operand::Reg(1), Operand::None).is_pure(&f));
+        assert!(Inst::new(OpCode::NULLISH, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
+        // 分配/常量/空操作
+        assert!(Inst::new(OpCode::NOP, Operand::None, Operand::None, Operand::None).is_pure(&f));
+        assert!(Inst::load_const(Operand::Reg(1), 0).is_pure(&f));
+        assert!(Inst::new(OpCode::VOID, Operand::Reg(1), Operand::None, Operand::None).is_pure(&f));
+        assert!(Inst::new(OpCode::TYPEOF, Operand::Reg(1), Operand::Reg(2), Operand::None).is_pure(&f));
+        assert!(Inst::new(OpCode::NEW_OBJECT, Operand::Reg(1), Operand::None, Operand::None).is_pure(&f));
+        assert!(Inst::new(OpCode::NEW_ARRAY, Operand::Reg(1), Operand::None, Operand::None).is_pure(&f));
+        // 闭包/单元读取
+        assert!(Inst::create_closure(Operand::Reg(1), 0).is_pure(&f));
+        assert!(Inst::new(OpCode::LOAD_UPVALUE, Operand::Reg(1), Operand::Imm(0), Operand::None).is_pure(&f));
+        assert!(Inst::new(OpCode::CELL_GET, Operand::Reg(0), Operand::Reg(1), Operand::Imm(0)).is_pure(&f));
+        // 模板字符串
+        assert!(Inst::template_str(Operand::Reg(1), 1, 10, &[0x1234]).is_pure(&f));
+        // LOAD_VAR 普通（a=Reg）纯
+        assert!(Inst::new(OpCode::LOAD_VAR, Operand::Reg(1), Operand::Reg(2), Operand::None).is_pure(&f));
+        // STORE_VAR 一律有副作用（Pitfall 6：顶层变量赋值全局可观察，不删）
+        assert!(!Inst::new(OpCode::STORE_VAR, Operand::Reg(0), Operand::Reg(1), Operand::None).is_pure(&f));
+        assert!(!Inst::new(OpCode::STORE_VAR, Operand::Reg(0), Operand::Reg(1), Operand::Imm(0)).is_pure(&f));
+        assert!(!Inst::new(OpCode::STORE_VAR, Operand::Reg(0), Operand::Reg(1), Operand::Imm(1)).is_pure(&f));
+    }
+
+    #[test]
+    fn impure_ops_are_not_deletable() {
+        let f = IRFunction::new();
+        // getter / 写对象属性
+        assert!(!Inst::ic_get(Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
+        assert!(!Inst::new(OpCode::GET_PROP, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
+        assert!(!Inst::new(OpCode::GET_PROP_DYNAMIC, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
+        assert!(!Inst::ic_set(Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
+        assert!(!Inst::new(OpCode::SET_PROP, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
+        assert!(!Inst::new(OpCode::SUPER_GET_PROP, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
+        assert!(!Inst::new(OpCode::DEFINE_ACCESSOR, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
+        assert!(!Inst::new(OpCode::DELETE_PROP_STATIC, Operand::Reg(0), Operand::Reg(0), Operand::None).is_pure(&f));
+        assert!(!Inst::new(OpCode::DELETE_PROP_DYNAMIC, Operand::Reg(0), Operand::None, Operand::Reg(2)).is_pure(&f));
+        // 调用 / 异常 / 控制流
+        assert!(!Inst::call(Operand::Reg(0), Operand::Reg(1), Operand::Reg(2), 0).is_pure(&f));
+        assert!(!Inst::call_native(Operand::Reg(0), Operand::Reg(1), Operand::Reg(2), 0).is_pure(&f));
+        assert!(!Inst::new_expression(Operand::Reg(3), Operand::Reg(0), Operand::Reg(1), 0).is_pure(&f));
+        assert!(!Inst::super_call(Operand::Reg(3), Operand::Reg(1), 0).is_pure(&f));
+        assert!(!Inst::new(OpCode::CREATE_REGEXP, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
+        assert!(!Inst::new(OpCode::RETURN, Operand::None, Operand::None, Operand::None).is_pure(&f));
+        assert!(!Inst::new(OpCode::THROW, Operand::Reg(2), Operand::None, Operand::None).is_pure(&f));
+        assert!(!Inst::new(OpCode::HALT, Operand::None, Operand::None, Operand::None).is_pure(&f));
+        assert!(!Inst::jmp(9).is_pure(&f));
+        assert!(!Inst::jmp_if_false(3, 9).is_pure(&f));
+        assert!(!Inst::try_begin(9).is_pure(&f));
+        assert!(!Inst::try_finally_begin(9).is_pure(&f));
+        // 迭代器 / 复合更新 / 写共享状态
+        assert!(!Inst::new(OpCode::FOR_IN_NEXT, Operand::Reg(0), Operand::None, Operand::None).is_pure(&f));
+        assert!(!Inst::new(OpCode::FOR_OF_NEXT, Operand::Reg(0), Operand::None, Operand::None).is_pure(&f));
+        assert!(!Inst::new(OpCode::INC_PRE, Operand::Reg(0), Operand::Reg(0), Operand::None).is_pure(&f));
+        assert!(!Inst::new(OpCode::COMPOUND_ADD, Operand::Reg(0), Operand::Reg(1), Operand::None).is_pure(&f));
+        assert!(!Inst::new(OpCode::MEMBER_INC, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
+        assert!(!Inst::new(OpCode::COMPOUND_MEMBER_ADD, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
+        assert!(!Inst::rest_object(Operand::Reg(0), Operand::Reg(1), 7).is_pure(&f));
+        assert!(!Inst::new(OpCode::INSTANCEOF, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
+        assert!(!Inst::new(OpCode::IN, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
+        assert!(!Inst::new(OpCode::GET_PRIVATE, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
+        assert!(!Inst::new(OpCode::SET_HOME_OBJECT, Operand::Reg(0), Operand::Reg(1), Operand::None).is_pure(&f));
+        assert!(!Inst::new(OpCode::STORE_UPVALUE, Operand::None, Operand::Reg(1), Operand::Imm(0)).is_pure(&f));
+        assert!(!Inst::new(OpCode::CELL_SET, Operand::None, Operand::Reg(1), Operand::Imm(0)).is_pure(&f));
+        assert!(!Inst::new(OpCode::MAKE_CELL, Operand::Reg(5), Operand::None, Operand::None).is_pure(&f));
+        // 占位 opcode 防御性有副作用
+        assert!(!Inst::new(OpCode::SWITCH_TABLE, Operand::None, Operand::None, Operand::None).is_pure(&f));
+    }
+
+    #[test]
+    fn store_var_all_branches_are_impure() {
+        // Pitfall 6：STORE_VAR 写目标变量寄存器，顶层/模块作用域变量全局可观察，一律不删
+        // （const guard 抛错、普通 var/let 赋值都可能改变外部观察状态）
+        let f = IRFunction::new();
+        assert!(!Inst::new(OpCode::STORE_VAR, Operand::Reg(0), Operand::Reg(1), Operand::None).is_pure(&f));
+        assert!(!Inst::new(OpCode::STORE_VAR, Operand::Reg(0), Operand::Reg(1), Operand::Imm(0)).is_pure(&f));
+        assert!(!Inst::new(OpCode::STORE_VAR, Operand::Reg(0), Operand::Reg(1), Operand::Imm(1)).is_pure(&f));
+    }
+
+    #[test]
+    fn load_var_this_derived_constructor_special_case() {
+        // a==This + is_derived_constructor 时读 this 可能抛 ReferenceError，不可删
+        let mut derived = IRFunction::new();
+        derived.is_derived_constructor = true;
+        let non_derived = IRFunction::new();
+
+        let this_load = Inst::new(OpCode::LOAD_VAR, Operand::Reg(1), Operand::This, Operand::None);
+        assert!(!this_load.is_pure(&derived));
+        assert!(this_load.is_pure(&non_derived));
+
+        // a=Reg 普通 LOAD_VAR 在 derived 函数中也纯
+        let reg_load = Inst::new(OpCode::LOAD_VAR, Operand::Reg(1), Operand::Reg(2), Operand::None);
+        assert!(reg_load.is_pure(&derived));
+    }
+}
diff --git a/crates/oxide_ir/src/inst.rs b/crates/oxide_ir/src/inst.rs
index acf00a71..97cbb6a7 100644
--- a/crates/oxide_ir/src/inst.rs
+++ b/crates/oxide_ir/src/inst.rs
@@ -2,12 +2,12 @@
 //!
 //! `ext` 内部是裸 u32（lowering 直拼字节码扩展字）。扩展字的**数量与语义值编码**
 //! 全部由 `inst_*` 构造 API 保证——emit 代码不直接触碰 `ext` 字段。
+//! 寄存器 def/use 契约与副作用判定在 `contract` 模块（`impl Inst`，DCE/liveness 共用）。
 
 use oxide_bytecode::opcode::OpCode;
 use smallvec::SmallVec;
 
 use crate::operand::{LabelId, Operand};
-use crate::IRFunction;
 
 /// IR 指令：opcode + 三个操作数槽（rd/a/b）+ 扩展字 `ext`。
 /// `ext` 内部是裸 u32，其数量与语义值编码由下方 `inst_*` 构造 API 保证。
@@ -206,274 +206,6 @@ impl Inst {
     pub fn try_finally_begin(label: LabelId) -> Self {
         Self::new(OpCode::TRY_FINALLY_BEGIN, Operand::None, Operand::None, Operand::Label(label))
     }
-
-    // ── 寄存器契约（DCE 与 liveness 共用，D-06）──
-
-    /// 本指令定义的寄存器（None 槽按 Reg(0) 映射；CALL 系含隐式 reg 0）。
-    /// 无写入返回 None。
-    pub fn def_reg(&self) -> Option<u32> {
-        match self.op {
-            // CALL 系：结果隐式写 reg 0，rd 是 callee use（Pitfall 1）
-            OpCode::CALL | OpCode::CALL_NATIVE => Some(0),
-            // GET_PROP 系：结果写 a/b 槽而非 rd（Pitfall 3）
-            OpCode::GET_PROP | OpCode::IC_GET_PROP => reg_of(&self.a),
-            OpCode::GET_PROP_DYNAMIC => reg_of(&self.b),
-            // 成员读写：val 槽原地更新（a 槽 / b 槽）
-            OpCode::MEMBER_INC | OpCode::MEMBER_DEC => reg_of(&self.a),
-            OpCode::DYN_MEMBER_INC | OpCode::DYN_MEMBER_DEC => reg_of(&self.b),
-            OpCode::COMPOUND_MEMBER_ADD
-            | OpCode::COMPOUND_MEMBER_SUB
-            | OpCode::COMPOUND_MEMBER_MUL
-            | OpCode::COMPOUND_MEMBER_DIV
-            | OpCode::COMPOUND_MEMBER_MOD
-            | OpCode::COMPOUND_MEMBER_EXP => reg_of(&self.a),
-            // 无 def：控制流 / 写共享状态 / 纯写对象
-            OpCode::HALT
-            | OpCode::RETURN
-            | OpCode::THROW
-            | OpCode::JMP
-            | OpCode::JMP_IF_FALSE
-            | OpCode::JMP_IF_TRUE
-            | OpCode::JMP_IF_NULLISH
-            | OpCode::TRY_BEGIN
-            | OpCode::TRY_END
-            | OpCode::TRY_FINALLY_BEGIN
-            | OpCode::TRY_FINALLY_END
-            | OpCode::MAKE_CELL
-            | OpCode::CELL_SET
-            | OpCode::STORE_UPVALUE
-            | OpCode::SET_PROP
-            | OpCode::SET_PROP_DYNAMIC
-            | OpCode::IC_SET_PROP
-            | OpCode::SET_ELEM
-            | OpCode::GET_PRIVATE
-            | OpCode::SET_PRIVATE
-            | OpCode::INIT_PRIVATE
-            | OpCode::PRIVATE_BRAND_IN
-            | OpCode::DELETE_PROP_STATIC
-            | OpCode::DELETE_PROP_DYNAMIC
-            | OpCode::DEFINE_ACCESSOR
-            | OpCode::SET_HOME_OBJECT
-            | OpCode::FOR_IN_INIT
-            | OpCode::FOR_OF_INIT
-            | OpCode::FOR_IN_CLEANUP
-            | OpCode::FOR_OF_CLOSE => None,
-            // 其余指令 rd 即 def（算术/比较/位/逻辑/加载族/迭代器 NEXT 等）
-            _ => reg_of(&self.rd),
-        }
-    }
-
-    /// 本指令读取的寄存器（None 槽按 Reg(0) 映射；HALT 特判 reg 0；TEMPLATE_STR 解析 ext）。
-    pub fn use_regs(&self) -> SmallVec<[u32; 4]> {
-        let mut uses = SmallVec::new();
-        match self.op {
-            // CALL 系：rd=callee, a=this, b..b+nargs 参数区间（Pitfall 1）
-            OpCode::CALL | OpCode::CALL_NATIVE => {
-                push_operand(&mut uses, &self.rd);
-                push_operand(&mut uses, &self.a);
-                let nargs = self.ext.first().copied().unwrap_or(0);
-                push_range(&mut uses, reg_of(&self.b), nargs);
-            }
-            // NEW_EXPRESSION：a=ctor, b..b+nargs
-            OpCode::NEW_EXPRESSION => {
-                push_operand(&mut uses, &self.a);
-                let nargs = self.ext.first().copied().unwrap_or(0);
-                push_range(&mut uses, reg_of(&self.b), nargs);
-            }
-            // SUPER_CALL：a..a+nargs
-            OpCode::SUPER_CALL => {
-                let nargs = self.ext.first().copied().unwrap_or(0);
-                push_range(&mut uses, reg_of(&self.a), nargs);
-            }
-            // GET_PROP 系：结果写 a/b 槽，rd=obj 是 use（Pitfall 3）
-            OpCode::GET_PROP => {
-                push_operand(&mut uses, &self.rd);
-                push_operand(&mut uses, &self.b);
-            }
-            OpCode::GET_PROP_DYNAMIC => {
-                push_operand(&mut uses, &self.rd);
-                push_operand(&mut uses, &self.a);
-            }
-            OpCode::IC_GET_PROP => {
-                push_operand(&mut uses, &self.a);
-                push_operand(&mut uses, &self.b);
-            }
-            // 成员更新：obj + key 是 use，val 槽是 def
-            OpCode::MEMBER_INC | OpCode::MEMBER_DEC => {
-                push_operand(&mut uses, &self.rd);
-                push_operand(&mut uses, &self.b);
-            }
-            OpCode::DYN_MEMBER_INC | OpCode::DYN_MEMBER_DEC => {
-                push_operand(&mut uses, &self.rd);
-                push_operand(&mut uses, &self.a);
-            }
-            OpCode::COMPOUND_MEMBER_ADD
-            | OpCode::COMPOUND_MEMBER_SUB
-            | OpCode::COMPOUND_MEMBER_MUL
-            | OpCode::COMPOUND_MEMBER_DIV
-            | OpCode::COMPOUND_MEMBER_MOD
-            | OpCode::COMPOUND_MEMBER_EXP => {
-                push_operand(&mut uses, &self.rd);
-                push_operand(&mut uses, &self.a);
-                push_operand(&mut uses, &self.b);
-            }
-            // 复合赋值：rd 与 a 都是 use（coerce 读双寄存器）
-            OpCode::COMPOUND_ADD
-            | OpCode::COMPOUND_SUB
-            | OpCode::COMPOUND_MUL
-            | OpCode::COMPOUND_DIV
-            | OpCode::COMPOUND_MOD
-            | OpCode::COMPOUND_EXP
-            | OpCode::COMPOUND_AND
-            | OpCode::COMPOUND_OR
-            | OpCode::COMPOUND_XOR
-            | OpCode::COMPOUND_SHL
-            | OpCode::COMPOUND_SHR
-            | OpCode::COMPOUND_USHR => {
-                push_operand(&mut uses, &self.rd);
-                push_operand(&mut uses, &self.a);
-            }
-            // 自增/自减：读 rd（写 rd 和 a）
-            OpCode::INC_PRE | OpCode::INC_POST | OpCode::DEC_PRE | OpCode::DEC_POST => {
-                push_operand(&mut uses, &self.rd);
-            }
-            // 二元运算：a, b
-            OpCode::ADD | OpCode::SUB | OpCode::MUL | OpCode::DIV | OpCode::MOD | OpCode::EQ
-            | OpCode::NEQ | OpCode::LT | OpCode::GT | OpCode::LTE | OpCode::GTE | OpCode::AND
-            | OpCode::OR | OpCode::NULLISH | OpCode::STRICT_EQ | OpCode::STRICT_NEQ
-            | OpCode::BIT_AND | OpCode::BIT_OR | OpCode::BIT_XOR | OpCode::SHL | OpCode::SHR
-            | OpCode::USHR | OpCode::INSTANCEOF | OpCode::IN | OpCode::CREATE_REGEXP => {
-                push_operand(&mut uses, &self.a);
-                push_operand(&mut uses, &self.b);
-            }
-            // 一元：a（emit 常 rd==a）
-            OpCode::NEG | OpCode::NOT | OpCode::UNARY_PLUS | OpCode::BIT_NOT | OpCode::TYPEOF => {
-                push_operand(&mut uses, &self.a);
-            }
-            // 无条件跳转 / try 标记：b 是 Label，无寄存器
-            OpCode::JMP | OpCode::TRY_BEGIN | OpCode::TRY_FINALLY_BEGIN | OpCode::TRY_END
-            | OpCode::TRY_FINALLY_END | OpCode::FOR_IN_CLEANUP | OpCode::FOR_OF_CLOSE => {}
-            // 条件跳转：rd=cond
-            OpCode::JMP_IF_FALSE | OpCode::JMP_IF_TRUE | OpCode::JMP_IF_NULLISH => {
-                push_operand(&mut uses, &self.rd);
-            }
-            // HALT：隐式读 reg 0（顶层返回值，Pitfall 2）
-            OpCode::HALT => uses.push(0),
-            // RETURN/THROW：读 rd（None→0）
-            OpCode::RETURN | OpCode::THROW => push_operand(&mut uses, &self.rd),
-            // 加载族：a 槽是 Const/Imm 立即数，无寄存器 use
-            OpCode::LOAD_CONST | OpCode::CREATE_CLOSURE | OpCode::LOAD_UPVALUE | OpCode::VOID
-            | OpCode::NEW_OBJECT | OpCode::NEW_ARRAY | OpCode::NOP => {}
-            // 变量读写：LOAD_VAR/STORE_VAR/CELL_GET 读 a（None→0）
-            OpCode::LOAD_VAR | OpCode::STORE_VAR | OpCode::CELL_GET => {
-                push_operand(&mut uses, &self.a);
-            }
-            // MAKE_CELL：cell 初值读 rd；CELL_SET/STORE_UPVALUE 读 a
-            OpCode::MAKE_CELL => push_operand(&mut uses, &self.rd),
-            OpCode::CELL_SET | OpCode::STORE_UPVALUE => push_operand(&mut uses, &self.a),
-            // 写对象属性：rd/a/b 全 use
-            OpCode::SET_PROP | OpCode::SET_PROP_DYNAMIC | OpCode::IC_SET_PROP | OpCode::SET_ELEM
-            | OpCode::GET_PRIVATE | OpCode::SET_PRIVATE | OpCode::INIT_PRIVATE
-            | OpCode::PRIVATE_BRAND_IN | OpCode::DEFINE_ACCESSOR => {
-                push_operand(&mut uses, &self.rd);
-                push_operand(&mut uses, &self.a);
-                push_operand(&mut uses, &self.b);
-            }
-            // delete：读 obj（+dynamic 读 key）
-            OpCode::DELETE_PROP_STATIC => push_operand(&mut uses, &self.rd),
-            OpCode::DELETE_PROP_DYNAMIC => {
-                push_operand(&mut uses, &self.rd);
-                push_operand(&mut uses, &self.b);
-            }
-            // super 属性读：a=this, b=key
-            OpCode::SUPER_GET_PROP | OpCode::SUPER_STATIC_GET_PROP => {
-                push_operand(&mut uses, &self.a);
-                push_operand(&mut uses, &self.b);
-            }
-            // SET_HOME_OBJECT：rd=func, a=home
-            OpCode::SET_HOME_OBJECT => {
-                push_operand(&mut uses, &self.rd);
-                push_operand(&mut uses, &self.a);
-            }
-            // for-in/of 迭代器：INIT 读 a；NEXT/DONE 读迭代器栈隐式状态
-            OpCode::FOR_IN_INIT | OpCode::FOR_OF_INIT => push_operand(&mut uses, &self.a),
-            OpCode::FOR_IN_NEXT | OpCode::FOR_IN_DONE | OpCode::FOR_OF_NEXT | OpCode::FOR_OF_DONE => {}
-            // REST_OBJECT：读 a（ext 是 excluded_idx 常量）
-            OpCode::REST_OBJECT => push_operand(&mut uses, &self.a),
-            // TEMPLATE_STR：解析 ext，跳过 ext[0]，后续 seg>>31==1 则低 8 位是 expr_reg（A1）
-            OpCode::TEMPLATE_STR => {
-                for seg in self.ext.iter().skip(1) {
-                    if seg >> 31 == 1 {
-                        uses.push(seg & 0xFF);
-                    }
-                }
-            }
-            // 占位 opcode（emit 不产）：按无 use 保守处理，不影响合法产物
-            OpCode::SWITCH_TABLE | OpCode::PROFILE_TYPE | OpCode::PROFILE_SHAPE
-            | OpCode::PROFILE_BRANCH | OpCode::PROFILE_CALL | OpCode::FORK | OpCode::JOIN => {}
-        }
-        uses
-    }
-}
-
-/// 操作数 → 物理寄存器号。None 槽映射 reg 0（A3，与 lower.rs operand_to_u8 一致）；
-/// Const/Imm/Label 不是寄存器槽，返回 None。
-fn reg_of(o: &Operand) -> Option<u32> {
-    match o {
-        Operand::Reg(r) => Some(*r),
-        Operand::This => Some(254),
-        Operand::NewTarget => Some(255),
-        Operand::None => Some(0),
-        Operand::Const(_) | Operand::Imm(_) | Operand::Label(_) => None,
-    }
-}
-
-/// 把寄存器操作数推入 use 集合（非寄存器槽跳过）。
-fn push_operand(uses: &mut SmallVec<[u32; 4]>, o: &Operand) {
-    if let Some(r) = reg_of(o) {
-        uses.push(r);
-    }
-}
-
-/// 推入连续参数区间 [first, first+nargs)。
-fn push_range(uses: &mut SmallVec<[u32; 4]>, first: Option<u32>, nargs: u32) {
-    if let Some(f) = first {
-        uses.extend((0..nargs).map(|i| f + i));
-    }
-}
-
-impl Inst {
-    /// 本指令是否无观察副作用（Pattern 1 纯表；LOAD_VAR 的 This+derived 特判需 &IRFunction）。
-    ///
-    /// 纯 = 结果未用时可删。表外 opcode 一律有副作用（D-05 精确表，宁少删不错删）。
-    pub fn is_pure(&self, f: &IRFunction) -> bool {
-        match self.op {
-            // 算术 / 比较 / 位 / 逻辑：coerce 对象路径有抛错风险，D-05 决策算纯（运行时等价兜底）
-            OpCode::ADD | OpCode::SUB | OpCode::MUL | OpCode::DIV | OpCode::MOD | OpCode::NEG
-            | OpCode::UNARY_PLUS | OpCode::EQ | OpCode::NEQ | OpCode::LT | OpCode::GT
-            | OpCode::LTE | OpCode::GTE | OpCode::STRICT_EQ | OpCode::STRICT_NEQ
-            | OpCode::BIT_AND | OpCode::BIT_OR | OpCode::BIT_XOR | OpCode::SHL | OpCode::SHR
-            | OpCode::USHR | OpCode::BIT_NOT | OpCode::AND | OpCode::OR | OpCode::NOT
-            | OpCode::NULLISH => true,
-            // 分配 / 常量 / 空操作（a 槽非寄存器）
-            OpCode::NOP | OpCode::LOAD_CONST | OpCode::VOID | OpCode::TYPEOF | OpCode::NEW_OBJECT
-            | OpCode::NEW_ARRAY => true,
-            // 闭包 / cell 读取：无抛错路径（D-07）
-            OpCode::CREATE_CLOSURE | OpCode::LOAD_UPVALUE | OpCode::CELL_GET => true,
-            // 模板字符串：纯拼接写 rd，无抛错（use 统计覆盖其 ext）
-            OpCode::TEMPLATE_STR => true,
-            // LOAD_VAR：仅 a==This 且 derived 构造函数读 this 可能抛 ReferenceError（misc.rs:52-63）
-            OpCode::LOAD_VAR => {
-                !(self.a == Operand::This && f.is_derived_constructor)
-            }
-            // STORE_VAR：写变量目标寄存器。脚本顶层/模块作用域的变量是**全局可观察状态**
-            // （Pitfall 6：`let x=0; class C{[x=1](){}}` 无后续本地读取时删除 `x=1` 会改变
-            // 外部 `assert(x===1)` 的观察结果）；函数内局部未用赋值的优化留给 Phase 5 精确活度。
-            OpCode::STORE_VAR => false,
-            // 其余全部有副作用（getter/调用/控制流/迭代器/复合更新/写共享状态/占位防御）
-            _ => false,
-        }
-    }
 }
 
 #[cfg(test)]
@@ -588,302 +320,4 @@ mod tests {
         assert_eq!(inst.ext[1], 0x1234);
         assert_eq!(inst.ext[2], 0x8000_0000 | 5);
     }
-
-    // ── def_reg / use_regs 契约测试（Pattern 2 表，反直觉槽位手工 IR 锁定）──
-
-    #[test]
-    fn binary_op_def_rd_use_ab() {
-        let inst = Inst::new(OpCode::ADD, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2));
-        assert_eq!(inst.def_reg(), Some(0));
-        assert_eq!(inst.use_regs().as_slice(), &[1, 2]);
-    }
-
-    #[test]
-    fn unary_op_def_rd_use_a() {
-        let inst = Inst::new(OpCode::NEG, Operand::Reg(0), Operand::Reg(1), Operand::None);
-        assert_eq!(inst.def_reg(), Some(0));
-        assert_eq!(inst.use_regs().as_slice(), &[1]);
-    }
-
-    #[test]
-    fn get_prop_def_is_a_slot_not_rd() {
-        // Pitfall 3：GET_PROP rd=obj 是 use，结果写 a 槽
-        let inst = Inst::new(OpCode::GET_PROP, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2));
-        assert_eq!(inst.def_reg(), Some(1));
-        assert_eq!(inst.use_regs().as_slice(), &[0, 2]);
-    }
-
-    #[test]
-    fn get_prop_dynamic_def_is_b_slot() {
-        // Pitfall 3：GET_PROP_DYNAMIC rd=obj 是 use，结果写 b 槽
-        let inst = Inst::new(OpCode::GET_PROP_DYNAMIC, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2));
-        assert_eq!(inst.def_reg(), Some(2));
-        assert_eq!(inst.use_regs().as_slice(), &[0, 1]);
-    }
-
-    #[test]
-    fn ic_get_prop_a_slot_is_use_and_def() {
-        // Pitfall 3：IC_GET_PROP a 槽既是对象 use 又是结果 def
-        let inst = Inst::ic_get(Operand::Reg(1), Operand::Reg(2));
-        assert_eq!(inst.def_reg(), Some(1));
-        let uses = inst.use_regs();
-        assert_eq!(uses.as_slice(), &[1, 2]);
-    }
-
-    #[test]
-    fn call_def_is_implicit_reg0_with_arg_range() {
-        // Pitfall 1：CALL rd=callee 是 use，结果隐式写 reg 0；参数 b..b+nargs 连续
-        let inst = Inst::call(Operand::Reg(0), Operand::Reg(1), Operand::Reg(2), 3);
-        assert_eq!(inst.def_reg(), Some(0));
-        assert_eq!(inst.use_regs().as_slice(), &[0, 1, 2, 3, 4]);
-    }
-
-    #[test]
-    fn call_native_def_is_implicit_reg0() {
-        let inst = Inst::call_native(Operand::Reg(0), Operand::Reg(1), Operand::Reg(2), 1);
-        assert_eq!(inst.def_reg(), Some(0));
-        assert_eq!(inst.use_regs().as_slice(), &[0, 1, 2]);
-    }
-
-    #[test]
-    fn new_expression_uses_ctor_and_arg_range() {
-        let inst = Inst::new_expression(Operand::Reg(3), Operand::Reg(0), Operand::Reg(1), 2);
-        assert_eq!(inst.def_reg(), Some(3));
-        assert_eq!(inst.use_regs().as_slice(), &[0, 1, 2]);
-    }
-
-    #[test]
-    fn super_call_uses_arg_range() {
-        let inst = Inst::super_call(Operand::Reg(3), Operand::Reg(1), 1);
-        assert_eq!(inst.def_reg(), Some(3));
-        assert_eq!(inst.use_regs().as_slice(), &[1]);
-    }
-
-    #[test]
-    fn halt_implicitly_uses_reg0() {
-        // Pitfall 2：HALT 返回 regs[0]，顶层 LOAD_VAR(None, r) 链靠它保活
-        let inst = Inst::new(OpCode::HALT, Operand::None, Operand::None, Operand::None);
-        assert_eq!(inst.def_reg(), None);
-        assert_eq!(inst.use_regs().as_slice(), &[0]);
-    }
-
-    #[test]
-    fn void_defs_rd_no_use() {
-        // VM 的 VOID handler 不读 a 槽
-        let inst = Inst::new(OpCode::VOID, Operand::Reg(1), Operand::Reg(2), Operand::None);
-        assert_eq!(inst.def_reg(), Some(1));
-        assert!(inst.use_regs().is_empty());
-    }
-
-    #[test]
-    fn load_const_create_closure_load_upvalue_no_use() {
-        // a 槽是 Const/Imm 立即数，非寄存器
-        let lc = Inst::load_const(Operand::Reg(1), 5);
-        assert_eq!(lc.def_reg(), Some(1));
-        assert!(lc.use_regs().is_empty());
-
-        let cc = Inst::create_closure(Operand::Reg(1), 0);
-        assert_eq!(cc.def_reg(), Some(1));
-        assert!(cc.use_regs().is_empty());
-
-        let lu = Inst::new(OpCode::LOAD_UPVALUE, Operand::Reg(1), Operand::Imm(0), Operand::None);
-        assert_eq!(lu.def_reg(), Some(1));
-        assert!(lu.use_regs().is_empty());
-    }
-
-    #[test]
-    fn none_slot_maps_to_reg0() {
-        // A3：None 槽与 lower.rs operand_to_u8 一致，统一映射物理 reg 0
-        let lv = Inst::new(OpCode::LOAD_VAR, Operand::Reg(1), Operand::None, Operand::None);
-        assert_eq!(lv.use_regs().as_slice(), &[0]);
-
-        let cg = Inst::new(OpCode::CELL_GET, Operand::Reg(0), Operand::None, Operand::Imm(0));
-        assert_eq!(cg.use_regs().as_slice(), &[0]);
-    }
-
-    #[test]
-    fn template_str_parses_expr_regs_from_ext() {
-        // ext[0] 跳过；后续 seg>>31==1 则低 8 位是 expr_reg（A1，emit 8 位编码）
-        let with_expr = Inst::template_str(Operand::Reg(1), 2, 10, &[0x1234, 0x8000_0000 | 5]);
-        assert_eq!(with_expr.use_regs().as_slice(), &[5]);
-
-        // 纯 quasi（无表达式）：不误报寄存器
-        let no_expr = Inst::template_str(Operand::Reg(1), 1, 10, &[0x1234]);
-        assert!(no_expr.use_regs().is_empty());
-    }
-
-    #[test]
-    fn jmp_if_false_uses_cond_reg() {
-        let inst = Inst::jmp_if_false(3, 9);
-        assert_eq!(inst.def_reg(), None);
-        assert_eq!(inst.use_regs().as_slice(), &[3]);
-    }
-
-    #[test]
-    fn jmp_and_try_no_use() {
-        assert!(Inst::jmp(9).use_regs().is_empty());
-        assert!(Inst::try_begin(9).use_regs().is_empty());
-        assert!(Inst::try_finally_begin(9).use_regs().is_empty());
-    }
-
-    #[test]
-    fn make_cell_no_def_uses_rd() {
-        let inst = Inst::new(OpCode::MAKE_CELL, Operand::Reg(5), Operand::None, Operand::None);
-        assert_eq!(inst.def_reg(), None);
-        assert_eq!(inst.use_regs().as_slice(), &[5]);
-    }
-
-    #[test]
-    fn cell_set_and_store_upvalue_use_a_no_def() {
-        let cs = Inst::new(OpCode::CELL_SET, Operand::None, Operand::Reg(1), Operand::Imm(0));
-        assert_eq!(cs.def_reg(), None);
-        assert_eq!(cs.use_regs().as_slice(), &[1]);
-
-        let su = Inst::new(OpCode::STORE_UPVALUE, Operand::None, Operand::Reg(1), Operand::Imm(0));
-        assert_eq!(su.def_reg(), None);
-        assert_eq!(su.use_regs().as_slice(), &[1]);
-    }
-
-    #[test]
-    fn return_throw_use_rd_with_none_mapping_reg0() {
-        let ret = Inst::new(OpCode::RETURN, Operand::None, Operand::None, Operand::None);
-        assert_eq!(ret.def_reg(), None);
-        assert_eq!(ret.use_regs().as_slice(), &[0]);
-
-        let thr = Inst::new(OpCode::THROW, Operand::Reg(2), Operand::None, Operand::None);
-        assert_eq!(thr.def_reg(), None);
-        assert_eq!(thr.use_regs().as_slice(), &[2]);
-    }
-
-    #[test]
-    fn rest_object_uses_a() {
-        let inst = Inst::rest_object(Operand::Reg(0), Operand::Reg(1), 7);
-        assert_eq!(inst.def_reg(), Some(0));
-        assert_eq!(inst.use_regs().as_slice(), &[1]);
-    }
-
-    #[test]
-    fn for_in_next_defs_rd_no_use() {
-        let inst = Inst::new(OpCode::FOR_IN_NEXT, Operand::Reg(0), Operand::None, Operand::None);
-        assert_eq!(inst.def_reg(), Some(0));
-        assert!(inst.use_regs().is_empty());
-    }
-
-    #[test]
-    fn store_var_def_rd_use_a() {
-        let inst = Inst::new(OpCode::STORE_VAR, Operand::Reg(0), Operand::Reg(1), Operand::None);
-        assert_eq!(inst.def_reg(), Some(0));
-        assert_eq!(inst.use_regs().as_slice(), &[1]);
-    }
-
-    // ── is_pure 契约测试（Pattern 1 表，纯/非纯族代表 opcode）──
-
-    #[test]
-    fn pure_ops_are_deletable() {
-        let f = IRFunction::new();
-        // 算术 / 比较 / 位 / 逻辑
-        assert!(Inst::new(OpCode::ADD, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
-        assert!(Inst::new(OpCode::SUB, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
-        assert!(Inst::new(OpCode::MUL, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
-        assert!(Inst::new(OpCode::NEG, Operand::Reg(0), Operand::Reg(1), Operand::None).is_pure(&f));
-        assert!(Inst::new(OpCode::EQ, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
-        assert!(Inst::new(OpCode::STRICT_EQ, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
-        assert!(Inst::new(OpCode::LT, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
-        assert!(Inst::new(OpCode::BIT_AND, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
-        assert!(Inst::new(OpCode::BIT_NOT, Operand::Reg(0), Operand::Reg(1), Operand::None).is_pure(&f));
-        assert!(Inst::new(OpCode::AND, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
-        assert!(Inst::new(OpCode::OR, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
-        assert!(Inst::new(OpCode::NOT, Operand::Reg(0), Operand::Reg(1), Operand::None).is_pure(&f));
-        assert!(Inst::new(OpCode::NULLISH, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
-        // 分配/常量/空操作
-        assert!(Inst::new(OpCode::NOP, Operand::None, Operand::None, Operand::None).is_pure(&f));
-        assert!(Inst::load_const(Operand::Reg(1), 0).is_pure(&f));
-        assert!(Inst::new(OpCode::VOID, Operand::Reg(1), Operand::None, Operand::None).is_pure(&f));
-        assert!(Inst::new(OpCode::TYPEOF, Operand::Reg(1), Operand::Reg(2), Operand::None).is_pure(&f));
-        assert!(Inst::new(OpCode::NEW_OBJECT, Operand::Reg(1), Operand::None, Operand::None).is_pure(&f));
-        assert!(Inst::new(OpCode::NEW_ARRAY, Operand::Reg(1), Operand::None, Operand::None).is_pure(&f));
-        // 闭包/单元读取
-        assert!(Inst::create_closure(Operand::Reg(1), 0).is_pure(&f));
-        assert!(Inst::new(OpCode::LOAD_UPVALUE, Operand::Reg(1), Operand::Imm(0), Operand::None).is_pure(&f));
-        assert!(Inst::new(OpCode::CELL_GET, Operand::Reg(0), Operand::Reg(1), Operand::Imm(0)).is_pure(&f));
-        // 模板字符串
-        assert!(Inst::template_str(Operand::Reg(1), 1, 10, &[0x1234]).is_pure(&f));
-        // LOAD_VAR 普通（a=Reg）纯
-        assert!(Inst::new(OpCode::LOAD_VAR, Operand::Reg(1), Operand::Reg(2), Operand::None).is_pure(&f));
-        // STORE_VAR 一律有副作用（Pitfall 6：顶层变量赋值全局可观察，不删）
-        assert!(!Inst::new(OpCode::STORE_VAR, Operand::Reg(0), Operand::Reg(1), Operand::None).is_pure(&f));
-        assert!(!Inst::new(OpCode::STORE_VAR, Operand::Reg(0), Operand::Reg(1), Operand::Imm(0)).is_pure(&f));
-        assert!(!Inst::new(OpCode::STORE_VAR, Operand::Reg(0), Operand::Reg(1), Operand::Imm(1)).is_pure(&f));
-    }
-
-    #[test]
-    fn impure_ops_are_not_deletable() {
-        let f = IRFunction::new();
-        // getter / 写对象属性
-        assert!(!Inst::ic_get(Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
-        assert!(!Inst::new(OpCode::GET_PROP, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
-        assert!(!Inst::new(OpCode::GET_PROP_DYNAMIC, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
-        assert!(!Inst::ic_set(Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
-        assert!(!Inst::new(OpCode::SET_PROP, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
-        assert!(!Inst::new(OpCode::SUPER_GET_PROP, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
-        assert!(!Inst::new(OpCode::DEFINE_ACCESSOR, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
-        assert!(!Inst::new(OpCode::DELETE_PROP_STATIC, Operand::Reg(0), Operand::Reg(0), Operand::None).is_pure(&f));
-        assert!(!Inst::new(OpCode::DELETE_PROP_DYNAMIC, Operand::Reg(0), Operand::None, Operand::Reg(2)).is_pure(&f));
-        // 调用 / 异常 / 控制流
-        assert!(!Inst::call(Operand::Reg(0), Operand::Reg(1), Operand::Reg(2), 0).is_pure(&f));
-        assert!(!Inst::call_native(Operand::Reg(0), Operand::Reg(1), Operand::Reg(2), 0).is_pure(&f));
-        assert!(!Inst::new_expression(Operand::Reg(3), Operand::Reg(0), Operand::Reg(1), 0).is_pure(&f));
-        assert!(!Inst::super_call(Operand::Reg(3), Operand::Reg(1), 0).is_pure(&f));
-        assert!(!Inst::new(OpCode::CREATE_REGEXP, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
-        assert!(!Inst::new(OpCode::RETURN, Operand::None, Operand::None, Operand::None).is_pure(&f));
-        assert!(!Inst::new(OpCode::THROW, Operand::Reg(2), Operand::None, Operand::None).is_pure(&f));
-        assert!(!Inst::new(OpCode::HALT, Operand::None, Operand::None, Operand::None).is_pure(&f));
-        assert!(!Inst::jmp(9).is_pure(&f));
-        assert!(!Inst::jmp_if_false(3, 9).is_pure(&f));
-        assert!(!Inst::try_begin(9).is_pure(&f));
-        assert!(!Inst::try_finally_begin(9).is_pure(&f));
-        // 迭代器 / 复合更新 / 写共享状态
-        assert!(!Inst::new(OpCode::FOR_IN_NEXT, Operand::Reg(0), Operand::None, Operand::None).is_pure(&f));
-        assert!(!Inst::new(OpCode::FOR_OF_NEXT, Operand::Reg(0), Operand::None, Operand::None).is_pure(&f));
-        assert!(!Inst::new(OpCode::INC_PRE, Operand::Reg(0), Operand::Reg(0), Operand::None).is_pure(&f));
-        assert!(!Inst::new(OpCode::COMPOUND_ADD, Operand::Reg(0), Operand::Reg(1), Operand::None).is_pure(&f));
-        assert!(!Inst::new(OpCode::MEMBER_INC, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
-        assert!(!Inst::new(OpCode::COMPOUND_MEMBER_ADD, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
-        assert!(!Inst::rest_object(Operand::Reg(0), Operand::Reg(1), 7).is_pure(&f));
-        assert!(!Inst::new(OpCode::INSTANCEOF, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
-        assert!(!Inst::new(OpCode::IN, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
-        assert!(!Inst::new(OpCode::GET_PRIVATE, Operand::Reg(0), Operand::Reg(1), Operand::Reg(2)).is_pure(&f));
-        assert!(!Inst::new(OpCode::SET_HOME_OBJECT, Operand::Reg(0), Operand::Reg(1), Operand::None).is_pure(&f));
-        assert!(!Inst::new(OpCode::STORE_UPVALUE, Operand::None, Operand::Reg(1), Operand::Imm(0)).is_pure(&f));
-        assert!(!Inst::new(OpCode::CELL_SET, Operand::None, Operand::Reg(1), Operand::Imm(0)).is_pure(&f));
-        assert!(!Inst::new(OpCode::MAKE_CELL, Operand::Reg(5), Operand::None, Operand::None).is_pure(&f));
-        // 占位 opcode 防御性有副作用
-        assert!(!Inst::new(OpCode::SWITCH_TABLE, Operand::None, Operand::None, Operand::None).is_pure(&f));
-    }
-
-    #[test]
-    fn store_var_all_branches_are_impure() {
-        // Pitfall 6：STORE_VAR 写目标变量寄存器，顶层/模块作用域变量全局可观察，一律不删
-        // （const guard 抛错、普通 var/let 赋值都可能改变外部观察状态）
-        let f = IRFunction::new();
-        assert!(!Inst::new(OpCode::STORE_VAR, Operand::Reg(0), Operand::Reg(1), Operand::None).is_pure(&f));
-        assert!(!Inst::new(OpCode::STORE_VAR, Operand::Reg(0), Operand::Reg(1), Operand::Imm(0)).is_pure(&f));
-        assert!(!Inst::new(OpCode::STORE_VAR, Operand::Reg(0), Operand::Reg(1), Operand::Imm(1)).is_pure(&f));
-    }
-
-    #[test]
-    fn load_var_this_derived_constructor_special_case() {
-        // a==This + is_derived_constructor 时读 this 可能抛 ReferenceError，不可删
-        let mut derived = IRFunction::new();
-        derived.is_derived_constructor = true;
-        let non_derived = IRFunction::new();
-
-        let this_load = Inst::new(OpCode::LOAD_VAR, Operand::Reg(1), Operand::This, Operand::None);
-        assert!(!this_load.is_pure(&derived));
-        assert!(this_load.is_pure(&non_derived));
-
-        // a=Reg 普通 LOAD_VAR 在 derived 函数中也纯
-        let reg_load = Inst::new(OpCode::LOAD_VAR, Operand::Reg(1), Operand::Reg(2), Operand::None);
-        assert!(reg_load.is_pure(&derived));
-    }
 }
diff --git a/crates/oxide_ir/src/lib.rs b/crates/oxide_ir/src/lib.rs
index 5d225c29..0d94cf75 100644
--- a/crates/oxide_ir/src/lib.rs
+++ b/crates/oxide_ir/src/lib.rs
@@ -11,6 +11,7 @@
 //!
 //! 分析视图（CFG/LiveInfo/AllocMap）是 pass 输出，不住进 IR。
 
+pub mod contract;
 pub mod inst;
 pub mod lower;
 pub mod operand;