落地 12.2 二十个用例目录：toml + .st + 期望表。

- tests/cases/ 01~20：13 正例 / 6 负例 / 1 运行时故障
- 负例冻结报错类别：非 GVL 写全局、同名全局、io.var 未声明、FUNCTION 写全局、未声明实例、循环调用
- tests/README 补充用例清单与点亮节奏

tests/cases/20_line1/EXPECTED.md

@@ -0,0 +1,11 @@
+# 期望：编译通过；I 组合 → `Q0_0` 与急停语义一致
+
+| I0_0 | I0_1 | EmergencyStop | Q0_0 |
+|---|---|---|---|
+| TRUE | FALSE | FALSE | TRUE |
+| TRUE | TRUE | FALSE | FALSE |
+| FALSE | FALSE | FALSE | FALSE |
+| TRUE | FALSE | TRUE | FALSE |
+
+- `Q0_0 = I0_0 AND NOT I0_1 AND NOT EmergencyStop`
+- 固定 I 序列跑两遍，槽位与工程哈希一致（回放确定性）

tests/cases/20_line1/globals.st

@@ -0,0 +1,7 @@
+(* globals.st *)
+VAR_GLOBAL
+    EmergencyStop : BOOL := FALSE;
+    I0_0 : BOOL;
+    I0_1 : BOOL;
+    Q0_0 : BOOL;
+END_VAR

tests/cases/20_line1/main.st

@@ -0,0 +1,8 @@
+(* main.st *)
+PROGRAM MAIN
+VAR
+    starter : MotorStarter;
+END_VAR
+    starter(start := I0_0, stop := I0_1);
+    Q0_0 := starter.Q;
+END_PROGRAM

tests/cases/20_line1/motor.st

@@ -0,0 +1,13 @@
+(* motor.st *)
+FUNCTION_BLOCK MotorStarter
+VAR_EXTERNAL
+    EmergencyStop : BOOL;
+END_VAR
+VAR_INPUT
+    start, stop : BOOL;
+END_VAR
+VAR_OUTPUT
+    Q : BOOL;
+END_VAR
+    Q := start AND NOT stop AND NOT EmergencyStop;
+END_FUNCTION_BLOCK

tests/cases/20_line1/project.toml

@@ -0,0 +1,28 @@
+[project]
+name = "line1"
+entry = "program MAIN"
+cycle_limit = 100000
+dt_ms = 10
+
+[files]
+st = ["globals.st", "motor.st", "main.st"]
+
+# 全工程只允许这一处出现 VAR_GLOBAL（第一版：单个文件）
+[gvl]
+file = "globals.st"
+
+# 可选：I/O 绑定。不创造变量，var 必须已在 GVL 里声明
+[[io.input]]
+var = "EmergencyStop"
+channel = 0
+bit = 2
+
+[[io.input]]
+var = "I0_0"
+channel = 0
+bit = 0
+
+[[io.output]]
+var = "Q0_0"
+channel = 0
+bit = 0