fix(run-ops split): gate topology split on the opt-in flag and tighten diagnostics

- gate runOpsTopology splitEnabled on RUN_OPS_SPLIT_ENABLED so provisioning
  both DSNs before flipping the flag cannot open a second pool or route writes
  ahead of the distinct-DB sentinel
- rethrow the original UnclassifiableRunId in the cross-seam guard so its
  value/valueLength keep reflecting the real waitpoint id
- log run-found-but-environment-unresolved distinctly from missing-run
- correct the RUN_OPS_DATABASE_URL doc comment (Prisma datasource, not the
  webapp runtime pool)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: d-cs

apps/webapp/app/db.server.ts

@@ -237,7 +237,8 @@ export function selectRunOpsTopology(
 // singletons use (captureInfrastructureErrors(tagDatasource(role, raw))).
 const runOpsTopology: RunOpsTopology = singleton("runOpsTopology", () => {
   const newUrl = env.TASK_RUN_DATABASE_URL;
-  const splitEnabled = !!newUrl && !!env.TASK_RUN_LEGACY_DATABASE_URL;
+  // Gate on the opt-in flag too: the distinct-DB sentinel only runs when the flag is on.
+  const splitEnabled = env.RUN_OPS_SPLIT_ENABLED && !!newUrl && !!env.TASK_RUN_LEGACY_DATABASE_URL;
 
   return selectRunOpsTopology(
     {

apps/webapp/app/env.server.ts

@@ -129,7 +129,8 @@ const EnvironmentSchema = z
     // Explicit positive opt-in. Split behavior is unreachable unless this is true
     // AND the distinct-DB sentinel confirms the two URLs are physically distinct DBs.
     RUN_OPS_SPLIT_ENABLED: BoolEnv.default(false),
-    // Canonical URL for the dedicated run-ops DB. Takes precedence over TASK_RUN_DATABASE_URL.
+    // Datasource URL for the dedicated run-ops Prisma schema (migrations/generation).
+    // The webapp runtime pool is driven by TASK_RUN_DATABASE_URL, not this var.
     RUN_OPS_DATABASE_URL: z
       .string()
       .refine(isValidDatabaseUrl, "RUN_OPS_DATABASE_URL is invalid")

apps/webapp/app/v3/eventRepository/index.server.ts

@@ -308,6 +308,12 @@ async function findRunForEventCreation(runId: string) {
   );
 
   if (!environment) {
+    // Run exists but its environment could not be resolved (e.g. a lagging replica
+    // under split); distinguish this from a genuinely missing run.
+    logger.warn("Run found but environment unresolved for event creation", {
+      runId,
+      runtimeEnvironmentId: foundRun.runtimeEnvironmentId,
+    });
     return null;
   }
 

apps/webapp/app/v3/runOpsMigration/crossSeamGuard.server.ts

@@ -1,4 +1,4 @@
-import { ownerEngine, UnclassifiableRunId } from "@trigger.dev/core/v3/isomorphic";
+import { ownerEngine } from "@trigger.dev/core/v3/isomorphic";
 import { isSplitEnabled } from "./splitMode.server";
 import type {
   CrossSeamGuardDecision,
@@ -56,16 +56,8 @@ export function selectStoreForWaitpoint(
 
   const classify = deps?.classify ?? ownerEngine;
 
-  let residency: RunOpsResidency;
-  try {
-    residency = classify(input.waitpointId);
-  } catch (error) {
-    // Loud on ambiguity: rethrow with context, never catch-and-default.
-    if (error instanceof UnclassifiableRunId) {
-      throw new UnclassifiableRunId(`${input.waitpointId} (routeKind=${input.routeKind})`);
-    }
-    throw error;
-  }
+  // Loud on ambiguity: classify throws UnclassifiableRunId with the real id; never catch-and-default.
+  const residency: RunOpsResidency = classify(input.waitpointId);
 
   const pinnedReason = applyPinningRules(input);
   const store: StoreTarget = pinnedReason ? "legacy" : storeForResidency(residency);