fix(jobs): 留痕清理独立接通历史存储开关；精简死逻辑并对齐陈旧注释

src/test/kotlin/com/gzzn/omms/msgexchange/PipelineSmokeTest.kt

@@ -219,7 +219,7 @@ class PipelineSmokeTest {
     }
 
     /**
-     * FIFO 修复（G2）端到端验收：兼容入口写入的高 ID **不会被提前领取**，
+     * FIFO 不变量"只领取已发现的行"端到端验收：兼容入口写入的高 ID **不会被提前领取**，
      * 必须等水位追平（较小 ID 补齐并入队）之后才按顺序处理。
      */
     @Test

src/test/kotlin/com/gzzn/omms/msgexchange/jobs/HistorySweepJobTest.kt

@@ -101,4 +101,21 @@ class HistorySweepJobTest {
         assertTrue(tombstone.payloadJson.contains("\"deleted\":true"))
         assertEquals(null, f.findMainRow("F3"))
     }
+
+    @Test
+    fun `snap log purge runs independently of the history store switch`() {
+        val f = seededFlight("F1", deleted = true, idleDays = 30)
+        var cutoff: Instant? = null
+        val purge = com.gzzn.omms.msgexchange.infra.persistence.SnapshotLogPurge { instant -> cutoff = instant; 7 }
+        val job = HistorySweepJob(
+            f, StubMsgEvents(), HistoryProps().apply { historyStoreEnabled = false }, snapLogPurge = purge,
+        )
+
+        val outcome = job.run(now)
+
+        assertEquals(7, outcome.snapLogPurged)      // 留痕清理不依赖历史存储开关
+        assertEquals(0, outcome.purged)             // 航班当前态仍一条不许删
+        assertTrue(f.findMainRow("F1") != null)
+        assertTrue(cutoff != null)
+    }
 }