fix: only keep v1_step_concurrency active when it has work

pkg/repository/sqlcv1/concurrency.sql

@@ -63,8 +63,9 @@ WHERE
 ;
 
 -- name: CheckStrategyActive :one
--- A strategy is active if the workflow is not deleted, and it is attached to the latest workflow version or it has
--- at least one concurrency slot that is not filled (the concurrency slot could be on the parent).
+-- A strategy is active if the workflow is not deleted and it has at least one concurrency slot
+-- (the concurrency slot could be on the parent). Strategies on idle workflows will be deactivated
+-- and re-activated by the after_v1_concurrency_slot_insert trigger when new work arrives.
 WITH latest_workflow_version AS (
     SELECT DISTINCT ON("workflowId")
         "workflowId",
@@ -118,10 +119,11 @@ WITH latest_workflow_version AS (
     SELECT
         EXISTS(SELECT 1 FROM latest_workflow_version) AND
         (
-            -- We must match the first active strategy, otherwise we could have another concurrency strategy
-            -- that is active and has this concurrency strategy as a child.
+            -- A task can flow through multiple step concurrency strategies sequentially via
+            -- v1_concurrency_slot.next_strategy_ids. If this strategy is not the lowest-id active
+            -- strategy on the workflow version, an earlier strategy is still draining and may
+            -- hand off a task here next — so we can't deactivate even if no slots exist yet.
             (first_active_strategy.id != @strategyId::bigint) OR
-            latest_workflow_version."workflowVersionId" = @workflowVersionId::uuid OR
             EXISTS(SELECT 1 FROM active_slot) OR
             EXISTS(SELECT 1 FROM active_parent_slot)
         ) AS "isActive"