fix(run-store): exclude id-less operations from the routed-shard counter

An operation with no id falls back to the default store rather than resolving to one,
so counting it as id-routed traffic inflated the default series during a ramp. The
counter now fires only when an id resolved the key.

Also moves the unroutable-id helper test next to its source.

Author: d-cs

apps/webapp/test/unroutableRead.test.ts …sMigration/unroutableRead.server.test.tsapps/webapp/test/unroutableRead.test.ts renamed to apps/webapp/app/v3/runOpsMigration/unroutableRead.server.test.ts apps/webapp/test/unroutableRead.test.ts renamed to apps/webapp/app/v3/runOpsMigration/unroutableRead.server.test.ts

@@ -1,6 +1,6 @@
 import { UnknownShardKey } from "@internal/run-store";
 import { describe, expect, it } from "vitest";
-import { undefinedOnUnroutableId } from "~/v3/runOpsMigration/unroutableRead.server";
+import { undefinedOnUnroutableId } from "./unroutableRead.server";
 
 // `RoutingRunStore.findRun` is not async: it resolves the shard and throws before returning
 // anything, so these stand in for a read that fails while the call expression is still being

internal-packages/run-store/src/runOpsStore.shardMap.test.ts

@@ -420,6 +420,16 @@ describe("RoutingRunStore #distinctStores — one entry per database", () => {
     expect(routed).toEqual([]);
   });
 
+  it("does not count an id-less operation against the default store", async () => {
+    const routed: string[] = [];
+    const { router } = buildNShardRouter(["a", "b"], { routed });
+
+    await router.findRun({ spanId: "s1" }, undefined);
+    await router.runInTransaction(undefined, async () => undefined);
+
+    expect(routed).toEqual([]);
+  });
+
   it("does not count the legacy leg of an unrouted probe", async () => {
     const routed: string[] = [];
     const { router } = buildNShardRouter(["a", "b"], { routed });

internal-packages/run-store/src/runOpsStore.ts

@@ -486,7 +486,10 @@ export class RoutingRunStore implements RunStore {
   }
 
   #routeOrNew(id: string | undefined): RunStore {
-    return this.#shardStoreRoutedById(this.#routeKeyOrDefault(id));
+    const key = this.#routeKeyOrDefault(id);
+    // An absent id fell back to the default store rather than resolving anywhere, so it is not
+    // traffic attributable to that shard.
+    return typeof id === "string" ? this.#shardStoreRoutedById(key) : this.#shardStore(key);
   }
 
   // WRITE routing is pure id-shape (cuid → LEGACY, run-ops id → NEW). A LEGACY-classified id is