feat(jobs): 提交后回填补偿落库 backfill_todo 并到期重试 (ACM2-29 P2-3)

- V1.3.2 迁移：backfill_todo 持久补偿表（attempts/next_attempt_at/last_error）
- BackfillTodoRepository 接口 + PG 实现与 stub；record 幂等 upsert
- BackfillSweepJob：到期重试，成功即删，失败指数退避（30s 起步封顶 15 分钟）；
  触发点 = InboxPoller 每轮心跳（重启即对账）+ JobExecutor BACKFILL_SWEEP 类型
- MessageProcessor/SnapshotFlow 回填失败落待办（成功终态不降级，业务不重放）；
  SKIPPED 重复报文同样补偿共享信箱回填，防止重复信件被反复轮询
- 新测试：扫描重试/退避/恢复对账 4 用例；快照回填失败落库断言；
  跳过路径补偿落库断言

验证：MSGX_PG_PORT=5433 真实 PG 全量 102 用例 0 失败 0 跳过 (ACM2-29)

src/main/kotlin/com/gzzn/omms/msgexchange/processing/Pump.kt

@@ -8,6 +8,7 @@ import com.gzzn.omms.msgexchange.domain.MsgEvent
 import com.gzzn.omms.msgexchange.domain.ProcState
 import com.gzzn.omms.msgexchange.domain.ProcStatus
 import com.gzzn.omms.msgexchange.domain.Targets
+import com.gzzn.omms.msgexchange.infra.persistence.BackfillTodoRepository
 import com.gzzn.omms.msgexchange.infra.persistence.CminmsgInboxRepository
 import com.gzzn.omms.msgexchange.infra.persistence.MsgEventRepository
 import com.gzzn.omms.msgexchange.infra.persistence.ProcStateRepository
@@ -121,6 +122,7 @@ class MessageProcessor(
     private val procFailure: ProcFailure,
     private val props: PipelineProps,
     private val txManager: PipelineTransactionManager,
+    private val backfillTodo: BackfillTodoRepository? = null,
 ) {
     private val log = org.slf4j.LoggerFactory.getLogger(MessageProcessor::class.java)
     private val flidRegex = Regex("<FLID>(.*?)</FLID>", RegexOption.IGNORE_CASE)
@@ -188,6 +190,8 @@ class MessageProcessor(
                 val owner = procState.ownerOfIdentity(identity) ?: -1L
                 log.info("duplicate-of:{} -> SKIPPED id={}", owner, head.cminmsgsId)
                 procState.update(head.cminmsgsId, ProcStatus.SKIPPED, lastError = "duplicate-of:$owner")
+                // 重复报文自身也是一条信箱记录：同样回填共享信箱，防止被反复轮询（失败落补偿）
+                compensateBackfill(head, decoded)
                 return
             }
         }
@@ -243,9 +247,33 @@ class MessageProcessor(
             inbox.backfillOnSuccess(head.cminmsgsId, decoded.meta.sndr, decoded.meta.type, decoded.meta.styp, decoded.meta.seqn)
         } catch (e: Exception) {
             log.error("backfill failed after SUCCEEDED id={} (compensation required)", head.cminmsgsId, e)
+            recordBackfillTodo(head.cminmsgsId, decoded, e)
         }
         log.info("SUCCEEDED id={} events={} flightChanges={}", head.cminmsgsId, events.size, decision.flightChanges.size)
     }
+
+    /** v2 §5：回填失败只落补偿待办（成功终态不降级，业务不重放）；由 BackfillSweepJob 到期重试。 */
+    private fun compensateBackfill(head: ProcState, decoded: DecodedMessage) {
+        try {
+            inbox.backfillOnSuccess(head.cminmsgsId, decoded.meta.sndr, decoded.meta.type, decoded.meta.styp, decoded.meta.seqn)
+        } catch (e: Exception) {
+            log.error("backfill failed for SKIPPED duplicate id={} (compensation required)", head.cminmsgsId, e)
+            recordBackfillTodo(head.cminmsgsId, decoded, e)
+        }
+    }
+
+    private fun recordBackfillTodo(cminmsgsId: Long, decoded: DecodedMessage, e: Exception) {
+        backfillTodo?.record(
+            BackfillTodoRepository.BackfillTask(
+                cminmsgsId = cminmsgsId,
+                sndr = decoded.meta.sndr,
+                type = decoded.meta.type,
+                styp = decoded.meta.styp,
+                seqn = decoded.meta.seqn,
+            ),
+            e.message ?: e.javaClass.simpleName,
+        ) ?: log.warn("no backfill-todo repository bound; compensation NOT persisted id={}", cminmsgsId)
+    }
 }
 
 /** 延迟装配占位（阶段 1 后续以 Micronaut Bean 替换直连构造）。 */

src/main/kotlin/com/gzzn/omms/msgexchange/processing/SnapshotFlow.kt

@@ -8,6 +8,7 @@ import com.gzzn.omms.msgexchange.domain.ProcStatus
 import com.gzzn.omms.msgexchange.domain.MsgEvent
 import com.gzzn.omms.msgexchange.domain.MsgKind
 import com.gzzn.omms.msgexchange.domain.Targets
+import com.gzzn.omms.msgexchange.infra.persistence.BackfillTodoRepository
 import com.gzzn.omms.msgexchange.infra.persistence.CminmsgInboxRepository
 import com.gzzn.omms.msgexchange.infra.persistence.FlightFields
 import com.gzzn.omms.msgexchange.infra.persistence.FlightFieldsJson
@@ -33,6 +34,7 @@ class SnapshotFlow(
     private val procFailure: ProcFailure,
     private val txManager: PipelineTransactionManager,
     private val inbox: CminmsgInboxRepository,
+    private val backfillTodo: BackfillTodoRepository? = null,
 ) {
     private val log = org.slf4j.LoggerFactory.getLogger(SnapshotFlow::class.java)
 
@@ -139,6 +141,16 @@ class SnapshotFlow(
             inbox.backfillOnSuccess(head.cminmsgsId, msg.meta.sndr, msg.meta.type, msg.meta.styp, msg.meta.seqn)
         } catch (e: Exception) {
             log.error("backfill failed after SUCCEEDED id={} (compensation required)", head.cminmsgsId, e)
+            backfillTodo?.record(
+                BackfillTodoRepository.BackfillTask(
+                    cminmsgsId = head.cminmsgsId,
+                    sndr = msg.meta.sndr,
+                    type = msg.meta.type,
+                    styp = msg.meta.styp,
+                    seqn = msg.meta.seqn,
+                ),
+                e.message ?: e.javaClass.simpleName,
+            ) ?: log.warn("no backfill-todo repository bound; compensation NOT persisted id={}", head.cminmsgsId)
         }
     }