refactor(processing): remove unused processing start field

processing_started_at 没有任何判据消费（终态只看尝试上限），删除字段、仓储接口与方法、主泵写入、重放清理、SELECT/映射与 H2 fixture，并新增 V7 DROP COLUMN；V1–V6 历史迁移不动。

验证：./gradlew test 123 tests / 0 fail；V7 的 DROP 与最终 schema 断言需真实 PG，本机无 Docker 时 FlywayMigrationTest 按既有 assumeTrue 跳过。

src/main/kotlin/com/gzzn/omms/msgexchange/domain/ProcState.kt

@@ -86,12 +86,5 @@ data class ProcState(
     val backfillAbandonedAt: Instant? = null,
     /** 放弃原因（`MISSING_ROW` / `TRANSIENT_DEADLINE`），供人工对账与恢复判断。 */
     val backfillAbandonedReason: String? = null,
-    /**
-     * 首次被主泵取得的时刻；重试不刷新。
-     *
-     * 当前没有判据消费它（终态只看尝试上限），保留作排障与后续扩展；写入方是
-     * [com.gzzn.omms.msgexchange.infra.persistence.ProcStateRepository.markProcessingStartedIfAbsent]。
-     */
-    val processingStartedAt: Instant? = null,
     val updatedAt: Instant = Instant.now(),
 )

src/main/kotlin/com/gzzn/omms/msgexchange/infra/persistence/Repositories.kt

@@ -59,9 +59,6 @@ interface ProcStateRepository {
     /** 当前队头：还没处理完的消息里 ID 最小的那条。 */
     fun headUnfinished(): ProcState?
 
-    /** 首次开始处理时记下稳定起点；重试不覆盖。 */
-    fun markProcessingStartedIfAbsent(msgId: Long, now: Instant)
-
     /** 给消息绑定业务身份；返回 false 表示这个身份已经被另一条消息占了（业务重复）。 */
     fun tryBindIdentity(msgId: Long, identityKey: String): Boolean
 

src/main/kotlin/com/gzzn/omms/msgexchange/infra/persistence/jdbc/JdbcPgRepositories.kt

@@ -107,16 +107,6 @@ class JdbcProcStateRepository(
             ::mapProcState,
         )
 
-    override fun markProcessingStartedIfAbsent(msgId: Long, now: Instant) {
-        ds.update(
-            "UPDATE proc_state SET processing_started_at = ? WHERE msg_id = ? AND processing_started_at IS NULL",
-            { ps ->
-                ps.setTimestamp(1, now.toSqlTimestamp())
-                ps.setLong(2, msgId)
-            },
-        )
-    }
-
     override fun tryBindIdentity(msgId: Long, identityKey: String): Boolean {
         ownerOfIdentity(identityKey)?.let { owner ->
             return owner == msgId
@@ -286,7 +276,7 @@ class JdbcProcStateRepository(
         if (errorClasses.isEmpty()) return 0
         val placeholders = errorClasses.joinToString(",") { "?" }
         return ds.update(
-            "UPDATE proc_state SET state = 'PENDING', attempts = 0, next_attempt_at = NULL, processing_started_at = NULL, updated_at = ? " +
+            "UPDATE proc_state SET state = 'PENDING', attempts = 0, next_attempt_at = NULL, updated_at = ? " +
                 "WHERE state IN ('FAILED', 'DEAD') AND error_class IN ($placeholders)",
             { ps ->
                 ps.setTimestamp(1, clock.instant().toSqlTimestamp())
@@ -339,7 +329,6 @@ class JdbcProcStateRepository(
         backfillError = rs.getString("backfill_error"),
         backfillAbandonedAt = rs.getInstant("backfill_abandoned_at"),
         backfillAbandonedReason = rs.getString("backfill_abandoned_reason"),
-        processingStartedAt = rs.getInstant("processing_started_at"),
         updatedAt = rs.getInstant("updated_at") ?: clock.instant(),
     )
 
@@ -347,7 +336,7 @@ class JdbcProcStateRepository(
         const val SELECT_PROC =
             "SELECT msg_id, state, identity_key, attempts, next_attempt_at, error_class, last_error, " +
                 "received_at, enqueued_at, backfill_at, backfill_next_at, backfill_attempts, backfill_error, " +
-                "backfill_abandoned_at, backfill_abandoned_reason, processing_started_at, updated_at FROM proc_state"
+                "backfill_abandoned_at, backfill_abandoned_reason, updated_at FROM proc_state"
     }
 }
 

src/main/kotlin/com/gzzn/omms/msgexchange/infra/stub/StubRepositories.kt

@@ -84,12 +84,6 @@ class StubProcState : ProcStateRepository {
     override fun headUnfinished(): ProcState? =
         rows.values.filter { it.state == ProcStatus.PENDING || it.state == ProcStatus.FAILED }.minByOrNull { it.msgId }
 
-    override fun markProcessingStartedIfAbsent(msgId: Long, now: Instant) {
-        rows[msgId]?.let { row ->
-            if (row.processingStartedAt == null) rows[msgId] = row.copy(processingStartedAt = now)
-        }
-    }
-
     override fun tryBindIdentity(msgId: Long, identityKey: String): Boolean {
         val owner = bound[identityKey]
         if (owner != null && owner != msgId) return false
@@ -216,7 +210,7 @@ class StubProcState : ProcStateRepository {
         var n = 0
         rows.forEach { (id, s) ->
             if (s.errorClass in errorClasses && (s.state == ProcStatus.FAILED || s.state == ProcStatus.DEAD)) {
-                rows[id] = s.copy(state = ProcStatus.PENDING, attempts = 0, nextAttemptAt = null, processingStartedAt = null)
+                rows[id] = s.copy(state = ProcStatus.PENDING, attempts = 0, nextAttemptAt = null)
                 n++
             }
         }

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

@@ -103,10 +103,7 @@ class Pump(
             head.state == ProcStatus.FAILED && (head.nextAttemptAt ?: Instant.EPOCH) > now ->
                 sleepQuietly(Duration.between(now, head.nextAttemptAt))
             // 其余情况（新消息，或退避到期的重试）交给处理入口
-            else -> {
-                procState.markProcessingStartedIfAbsent(head.msgId, now)
-                processor.processOne(head)
-            }
+            else -> processor.processOne(head)
         }
     }
 

src/main/resources/db/migration/V7__drop_processing_started_at.sql

@@ -0,0 +1,14 @@
+-- =====================================================================
+-- V7：PROC_STATE 删除 PROCESSING_STARTED_AT
+-- ---------------------------------------------------------------------
+-- 只动自有 PostgreSQL；共享 MySQL 不建表、不改结构。
+--
+-- 该列由 V3 引入（原 HOL deadline 的稳定处理起点），但代码里没有任何判据消费它：
+-- 处理终态只看尝试上限（`PARAM:msgx.pipeline.max-attempts`）。按精简原则删除列与
+-- 全部读写路径，不留"以后也许有用"的死字段；将来若为 `CLM-9` 需要处理开始时间，
+-- 先写文档再实现。
+--
+-- 已发布的迁移历史（V1–V6）保持不变。
+-- =====================================================================
+
+ALTER TABLE PROC_STATE DROP COLUMN PROCESSING_STARTED_AT;