fix(webapp): keep the runs-list region filter in WHERE, not PREWHERE

The region filter uses if(region != "", region, worker_queue): a run is
region="" at trigger (so the expression yields worker_queue) and gets a real
region at dequeue, so the expression flips from one non-empty value to another
across a run versions. Under PREWHERE that is evaluated before FINAL reconciles
versions, so it could keep a stale pre-dequeue version and drop the winner,
returning runs whose current region no longer matches (and listRunIds drives
bulk actions). Moved it back to WHERE (post-FINAL) with a regression test.

Author: ericallam

apps/webapp/app/services/runsRepository/clickhouseRunsRepository.server.ts

@@ -416,10 +416,13 @@ export class ClickHouseRunsRepository implements IRunsRepository {
  *
  * Immutable / additive-only columns go in PREWHERE so ClickHouse filters (and, for `tags`, uses
  * the skip index) before FINAL reconciles versions and before materialising the wide columns,
- * which is what bounds memory on these scans. `status` is the one lifecycle-mutable filter, so it
- * stays in WHERE (post-FINAL): PREWHERE-ing it would keep a stale version and drop the winner. The
- * `(organization_id, project_id, environment_id)` primary-key prefix and the `created_at` range
- * stay in WHERE so they keep driving primary-key and partition pruning.
+ * which is what bounds memory on these scans. A filter stays in WHERE (post-FINAL) when its truth
+ * value can flip across a run's versions, since PREWHERE could then keep a stale version and drop
+ * the winner: `status` (lifecycle-mutable), and `regions` (its `if(region != '', region,
+ * worker_queue)` expression yields the worker_queue before dequeue and the region after, two
+ * different non-empty values). The `(organization_id, project_id, environment_id)` primary-key
+ * prefix and the `created_at` range stay in WHERE so they keep driving primary-key and partition
+ * pruning.
  */
 function applyRunFiltersToQueryBuilder<T>(
   queryBuilder: ClickhouseQueryBuilder<T>,
@@ -440,6 +443,12 @@ function applyRunFiltersToQueryBuilder<T>(
     queryBuilder.where("status IN {statuses: Array(String)}", { statuses: options.statuses });
   }
 
+  if (options.regions && options.regions.length > 0) {
+    queryBuilder.where("if(region != '', region, worker_queue) IN {regions: Array(String)}", {
+      regions: options.regions,
+    });
+  }
+
   // Period is a number of milliseconds duration
   if (options.period) {
     queryBuilder.where("created_at >= fromUnixTimestamp64Milli({period: Int64})", {
@@ -508,12 +517,6 @@ function applyRunFiltersToQueryBuilder<T>(
     queryBuilder.prewhere("queue IN {queues: Array(String)}", { queues: options.queues });
   }
 
-  if (options.regions && options.regions.length > 0) {
-    queryBuilder.prewhere("if(region != '', region, worker_queue) IN {regions: Array(String)}", {
-      regions: options.regions,
-    });
-  }
-
   if (options.machines && options.machines.length > 0) {
     queryBuilder.prewhere("machine_preset IN {machines: Array(String)}", {
       machines: options.machines,

apps/webapp/test/runsListQueryShape.test.ts

@@ -74,4 +74,43 @@ describe("runs list query shape (PREWHERE routing under FINAL)", () => {
       expect(runIds.sort()).toEqual([pendingOld.id, pendingRecent.id].sort());
     }
   );
+
+  containerTest(
+    "region filter uses the post-FINAL effective region, not a pre-dequeue worker_queue version",
+    async ({ clickhouseContainer, prisma }) => {
+      const clickhouse = new ClickHouse({
+        url: clickhouseContainer.getConnectionUrl(),
+        name: "query-shape-region-test",
+      });
+
+      const ctx = await seedParents(prisma, "region");
+      const run = await createRun(prisma, ctx, { friendlyId: "run_region" });
+
+      const shared = {
+        taskIdentifier: "webhook.deliver",
+        workerQueue: "wq-legacy",
+        createdAt: new Date(Date.now() - 1 * DAY_MS),
+      };
+
+      await insertTaskRunV2Rows(clickhouse, [
+        { ...run, ...shared, region: "", updatedAt: new Date(Date.now() - 2 * DAY_MS) },
+        { ...run, ...shared, region: "us-east-1", updatedAt: new Date(Date.now() - 1 * DAY_MS) },
+      ]);
+
+      const repository = new RunsRepository({ prisma, clickhouse });
+      const listArgs = {
+        page: { size: 10 } as const,
+        period: "365d",
+        organizationId: ctx.organizationId,
+        projectId: ctx.projectId,
+        environmentId: ctx.environmentId,
+      };
+
+      const byRegion = await repository.listRunIds({ ...listArgs, regions: ["us-east-1"] });
+      expect(byRegion.runIds).toEqual([run.id]);
+
+      const byWorkerQueue = await repository.listRunIds({ ...listArgs, regions: ["wq-legacy"] });
+      expect(byWorkerQueue.runIds).toEqual([]);
+    }
+  );
 });