diff --git a/server-rs/crates/spacetime-module/src/external_generation.rs b/server-rs/crates/spacetime-module/src/external_generation.rs
index ab09c27c3..91f0758ba 100644
--- a/server-rs/crates/spacetime-module/src/external_generation.rs
+++ b/server-rs/crates/spacetime-module/src/external_generation.rs
@@ -1,5 +1,6 @@
 use crate::*;
 use std::cmp::Ordering;
+use std::collections::HashMap;
 use std::ops::RangeFrom;
 
 const EXTERNAL_GENERATION_STATUS_PENDING: &str = "pending";
@@ -885,14 +886,23 @@ fn claim_external_generation_jobs_tx(
     });
 
     let mut claimed = Vec::new();
+    let mut concurrency = ExternalGenerationOwnerConcurrencyCache::default();
     for mut row in candidates.into_iter().take(limit) {
         if external_generation_job_has_exhausted_attempts(&row) {
+            let owner_user_id = row.owner_user_id.clone();
             finalize_external_generation_job_after_lease_exhaustion(ctx, row, claim_time)?;
+            // 终结可能把 running 行改成 failed，账号计数缓存随之失效。
+            concurrency.invalidate_running(&owner_user_id);
             continue;
         }
         // 会员并发上限：只约束 `pending → running` 的认领。达上限的任务留在 `pending` 天然排队；
         // 账号自己那条已过期的 `running` 回收不受限，否则超限账号的卡死任务永远无法回收。
-        if !external_generation_owner_has_concurrency_capacity(ctx, &row, claim_time) {
+        if !external_generation_owner_has_concurrency_capacity(
+            ctx,
+            &mut concurrency,
+            &row,
+            claim_time,
+        ) {
             continue;
         }
         let next_attempt = row.attempt.saturating_add(1);
@@ -921,33 +931,77 @@ fn claim_external_generation_jobs_tx(
             Some(worker_id.clone()),
             claim_time,
         );
+        // 本次认领把一行推进到 running，账号计数缓存失效，后续候选行重新现查。
+        concurrency.invalidate_running(&row.owner_user_id);
         claimed.push(map_external_generation_job_row(row));
     }
 
     Ok(claimed)
 }
 
+/// 单次 claim 事务内按账号缓存有效并发上限与 running 行数。
+///
+/// 上限在一次事务内是常量；running 计数在账号的任一行被认领或终结后立即失效、下次重查，
+/// 因此判定结果与逐候选行现查一致，只是把同一账号的重复查询折叠为一次。
+#[derive(Default)]
+struct ExternalGenerationOwnerConcurrencyCache {
+    limits: HashMap<String, u32>,
+    running: HashMap<String, u32>,
+}
+
+impl ExternalGenerationOwnerConcurrencyCache {
+    fn limit(&mut self, ctx: &ReducerContext, owner_user_id: &str) -> u32 {
+        if let Some(limit) = self.limits.get(owner_user_id) {
+            return *limit;
+        }
+        let limit = crate::effective_profile_concurrent_job_limit(ctx, owner_user_id);
+        self.limits.insert(owner_user_id.to_string(), limit);
+        limit
+    }
+
+    fn running_count(&mut self, ctx: &ReducerContext, owner_user_id: &str) -> u32 {
+        if let Some(count) = self.running.get(owner_user_id) {
+            return *count;
+        }
+        let count = count_running_external_generation_jobs_for_owner(ctx, owner_user_id);
+        self.running.insert(owner_user_id.to_string(), count);
+        count
+    }
+
+    /// 账号任一 `running` 行发生状态变化（认领 / 终结）后调用，保证下次读取重新现查。
+    fn invalidate_running(&mut self, owner_user_id: &str) {
+        self.running.remove(owner_user_id);
+    }
+
+    fn allows(&mut self, ctx: &ReducerContext, owner_user_id: &str, is_recycling: bool) -> bool {
+        let limit = self.limit(ctx, owner_user_id);
+        if is_unlimited_concurrency(limit) {
+            return true;
+        }
+        // 回收豁免不需要计数：自身过期 running 已计入在飞数，放行不会推高它。
+        let running = if is_recycling {
+            0
+        } else {
+            self.running_count(ctx, owner_user_id)
+        };
+        external_generation_claim_within_concurrency_limit(is_recycling, running, limit)
+    }
+}
+
 /// 认领前的并发上限判定。
 ///
 /// 计数只算 `status = running`（含 lease 过期待回收的 `expired_running`）：`pending`（含延时重试）
 /// 不占名额，失败退回 `pending` 会自然释放。`128` 哨兵由 [`is_unlimited_concurrency`] 解释。
 fn external_generation_owner_has_concurrency_capacity(
     ctx: &ReducerContext,
+    cache: &mut ExternalGenerationOwnerConcurrencyCache,
     row: &ExternalGenerationJob,
     now: Timestamp,
 ) -> bool {
-    let limit = crate::effective_profile_concurrent_job_limit(ctx, &row.owner_user_id);
-    if is_unlimited_concurrency(limit) {
-        return true;
-    }
     // 回收豁免：候选本身已是该账号过期的 `running`，它已计入在飞数；放行回收不会推高在飞任务数。
     let is_recycling = row.status == EXTERNAL_GENERATION_STATUS_RUNNING
         && is_external_generation_job_claimable(row, now);
-    external_generation_claim_within_concurrency_limit(
-        is_recycling,
-        count_running_external_generation_jobs_for_owner(ctx, &row.owner_user_id),
-        limit,
-    )
+    cache.allows(ctx, &row.owner_user_id, is_recycling)
 }
 
 /// 并发上限判定（纯函数）：`running_count >= limit` 时只放行对账号自身过期 `running` 的回收。
@@ -3936,6 +3990,18 @@ mod tests {
         ));
     }
 
+    #[test]
+    fn owner_concurrency_cache_only_invalidates_running_count() {
+        let mut cache = ExternalGenerationOwnerConcurrencyCache::default();
+        cache.running.insert("owner-a".to_string(), 2);
+        cache.limits.insert("owner-a".to_string(), 3);
+        // 认领 / 终结后 running 计数必须重查，否则会把上一行的变更带到下一候选行。
+        cache.invalidate_running("owner-a");
+        assert!(cache.running.get("owner-a").is_none());
+        // 上限在一次事务内是常量，不受 running 计数失效影响。
+        assert_eq!(cache.limits.get("owner-a"), Some(&3));
+    }
+
     fn micros(value: i64) -> Timestamp {
         Timestamp::from_micros_since_unix_epoch(value)
     }