refactor(webapp): drop FK on env default region; reuse canonical resolver

- RuntimeEnvironment.defaultWorkerGroupId is now a plain nullable column (no FK,
  no relation, no index): a deleted region is tolerated and resolution falls back
  to project -> global. Avoids Prisma drift and FK-check overhead on a cold table.
- api.v1.workers and computeTemplateCreation.resolveMode now reuse
  getDefaultWorkerGroupForProject instead of re-reading the global flag, so their
  isDefault / MICROVM decisions match exactly where runs route (and resolve the
  global default the same way as the trigger path).

Author: myftija

apps/webapp/app/routes/api.v1.workers.ts

@@ -4,14 +4,10 @@ import {
   WorkersCreateResponseBody,
   WorkersListResponseBody,
 } from "@trigger.dev/core/v3";
-import { $replica } from "~/db.server";
 import {
   createActionApiRoute,
   createLoaderApiRoute,
 } from "~/services/routeBuilders/apiBuilder.server";
-import { FEATURE_FLAG } from "~/v3/featureFlags";
-import { makeFlag } from "~/v3/featureFlags.server";
-import { resolveEffectiveDefaultWorkerGroupId } from "~/v3/regionAccess.server";
 import { WorkerGroupService } from "~/v3/services/worker/workerGroupService.server";
 
 export const loader = createLoaderApiRoute(
@@ -31,23 +27,19 @@ export const loader = createLoaderApiRoute(
       projectId: authentication.environment.projectId,
     });
 
-    const globalDefaultWorkerGroupId = await makeFlag($replica)({
-      key: FEATURE_FLAG.defaultWorkerInstanceGroupId,
-    });
-
-    // env default -> project default -> global default
-    const effectiveDefaultWorkerGroupId = resolveEffectiveDefaultWorkerGroupId({
+    // Reuse the trigger path's resolution so isDefault matches where runs
+    // actually route: env default -> project default -> global default.
+    const defaultWorkerGroup = await service.getDefaultWorkerGroupForProject({
+      projectId: authentication.environment.projectId,
       environmentDefaultWorkerGroupId: authentication.environment.defaultWorkerGroupId,
-      projectDefaultWorkerGroupId: authentication.environment.project.defaultWorkerGroupId,
-      globalDefaultWorkerGroupId,
     });
 
     return json(
       workers.map((w) => ({
         type: w.type,
         name: w.name,
         description: w.description,
-        isDefault: w.id === effectiveDefaultWorkerGroupId,
+        isDefault: w.id === defaultWorkerGroup?.id,
         updatedAt: w.updatedAt,
       }))
     );

apps/webapp/app/services/upsertBranch.server.ts

@@ -120,9 +120,7 @@ export class UpsertBranchService {
           shortcode,
           maximumConcurrencyLimit: parentEnvironment.maximumConcurrencyLimit,
           // Inherit the region from the parent preview environment.
-          defaultWorkerGroup: parentEnvironment.defaultWorkerGroupId
-            ? { connect: { id: parentEnvironment.defaultWorkerGroupId } }
-            : undefined,
+          defaultWorkerGroupId: parentEnvironment.defaultWorkerGroupId,
           organization: {
             connect: {
               id: parentEnvironment.organization.id,

apps/webapp/app/v3/services/computeTemplateCreation.server.ts

@@ -8,9 +8,8 @@ import type { PrismaClientOrTransaction } from "~/db.server";
 import type { AuthenticatedEnvironment } from "~/services/apiAuth.server";
 import { ServiceValidationError } from "./baseService.server";
 import { FailDeploymentService } from "./failDeployment.server";
-import { resolveComputeAccess, resolveEffectiveDefaultWorkerGroupId } from "../regionAccess.server";
-import { FEATURE_FLAG } from "../featureFlags";
-import { makeFlag } from "../featureFlags.server";
+import { resolveComputeAccess } from "../regionAccess.server";
+import { WorkerGroupService } from "./worker/workerGroupService.server";
 
 type TemplateCreationMode = "required" | "shadow" | "skip";
 
@@ -146,7 +145,6 @@ export class ComputeTemplateCreationService {
     const project = await prisma.project.findFirst({
       where: { id: authenticatedEnv.projectId },
       select: {
-        defaultWorkerGroupId: true,
         organization: {
           select: { featureFlags: true },
         },
@@ -157,23 +155,13 @@ export class ComputeTemplateCreationService {
       return "skip";
     }
 
-    // Resolve the region this env actually deploys to: env default -> project default -> global default.
-    const globalDefaultWorkerGroupId = await makeFlag(prisma)({
-      key: FEATURE_FLAG.defaultWorkerInstanceGroupId,
-    });
-    const effectiveDefaultWorkerGroupId = resolveEffectiveDefaultWorkerGroupId({
+    // Reuse the trigger path's resolution so the template decision matches the
+    // region runs actually deploy to: env default -> project default -> global default.
+    const defaultWorkerGroup = await new WorkerGroupService().getDefaultWorkerGroupForProject({
+      projectId: authenticatedEnv.projectId,
       environmentDefaultWorkerGroupId: authenticatedEnv.defaultWorkerGroupId,
-      projectDefaultWorkerGroupId: project.defaultWorkerGroupId,
-      globalDefaultWorkerGroupId,
     });
 
-    const defaultWorkerGroup = effectiveDefaultWorkerGroupId
-      ? await prisma.workerInstanceGroup.findFirst({
-          where: { id: effectiveDefaultWorkerGroupId },
-          select: { workloadType: true },
-        })
-      : null;
-
     if (defaultWorkerGroup?.workloadType === "MICROVM") {
       return "required";
     }

internal-packages/database/prisma/migrations/20260609142054_add_environment_default_worker_group/migration.sql

@@ -1,6 +1,2 @@
 -- AlterTable
 ALTER TABLE "public"."RuntimeEnvironment" ADD COLUMN IF NOT EXISTS "defaultWorkerGroupId" TEXT;
-
--- AddForeignKey
-ALTER TABLE "public"."RuntimeEnvironment" DROP CONSTRAINT IF EXISTS "RuntimeEnvironment_defaultWorkerGroupId_fkey";
-ALTER TABLE "public"."RuntimeEnvironment" ADD CONSTRAINT "RuntimeEnvironment_defaultWorkerGroupId_fkey" FOREIGN KEY ("defaultWorkerGroupId") REFERENCES "public"."WorkerInstanceGroup"("id") ON DELETE SET NULL ON UPDATE CASCADE;

internal-packages/database/prisma/migrations/20260609142055_add_environment_default_worker_group_index/migration.sql

@@ -354,8 +354,8 @@ model RuntimeEnvironment {
   orgMember   OrgMember? @relation(fields: [orgMemberId], references: [id], onDelete: SetNull, onUpdate: Cascade)
   orgMemberId String?
 
-  /// The default region for this environment. Falls back to the project default, then the global default.
-  defaultWorkerGroup   WorkerInstanceGroup? @relation("EnvironmentDefaultWorkerGroup", fields: [defaultWorkerGroupId], references: [id])
+  /// The default region (WorkerInstanceGroup) for this environment. Deliberately not a foreign key:
+  /// a deleted region is tolerated — resolution falls back to the project default, then the global default.
   defaultWorkerGroupId String?
 
   createdAt DateTime @default(now())
@@ -401,7 +401,6 @@ model RuntimeEnvironment {
   @@index([parentEnvironmentId])
   @@index([projectId])
   @@index([organizationId])
-  @@index([defaultWorkerGroupId])
 }
 
 /// Records of previously-valid API keys that are still accepted for authentication
@@ -1522,8 +1521,7 @@ model WorkerInstanceGroup {
   workers           WorkerInstance[]
   backgroundWorkers BackgroundWorker[]
 
-  defaultForProjects     Project[]            @relation("ProjectDefaultWorkerGroup")
-  defaultForEnvironments RuntimeEnvironment[] @relation("EnvironmentDefaultWorkerGroup")
+  defaultForProjects Project[] @relation("ProjectDefaultWorkerGroup")
 
   organization   Organization? @relation(fields: [organizationId], references: [id], onDelete: Cascade, onUpdate: Cascade)
   organizationId String?