@@ -0,0 +1,29 @@
+---
+"@trigger.dev/core": patch
+"@trigger.dev/sdk": patch
+---
+
+Runs can now be pinned to the deployment that your calling code came from, so a request served by an old release never triggers tasks from a new one.
+
+Deploy with an id — a commit SHA, a CI run id, a release tag — and give the running app the same value:
+
+```bash
+trigger.dev deploy --external-id "$COMMIT_SHA"
+TRIGGER_EXTERNAL_DEPLOYMENT_ID="$COMMIT_SHA"
+```
+
+Every trigger from that app then runs on that deployment's tasks. On Vercel, Railway, Render, Cloudflare Pages, Koyeb and most CI systems you can skip the second line and set `TRIGGER_AUTOMATIC_SKEW_VERSION_PROTECTION=1` instead — the SDK finds the commit itself. You can also set it per call:
+
+```ts
+await myTask.trigger({ foo: "bar" }, { externalDeploymentId: commitSha });
+```
+
+**While the deployment is still building**, the run waits instead of running on the wrong version. It starts as soon as a deployment carrying that id finishes, pinned to it. This is the normal case when your app deploys before its tasks finish building.
+
+**If the deployment never arrives** — the build failed, or nothing was ever deployed under that id — the run waits for an hour and then expires, and the error names the id it was waiting for. It is never quietly sent to a different release. Trigger a run with an id you have not deployed yet and this is what you get, so an id typo shows up as an expired run rather than a run on the wrong code.
+
+**If several deployments share one id**, the run goes to the highest version among them. This is what you get after `trigger.dev deploy --external-id "$COMMIT_SHA" --force`, which builds a second deployment for an id that already has one: both are kept and new runs use the newer.
+
+Triggering repeatedly with the same id is stable — every run lands on the same deployment until a newer one claims that id.
+
+An explicit `version` (or `TRIGGER_VERSION`) still takes precedence over the id, and triggers that send no id behave exactly as before.
@@ -488,6 +488,30 @@ const EnvironmentSchema = z
       .default(process.env.REDIS_TLS_DISABLED ?? "false"),
     TASK_META_CACHE_CURRENT_ENV_TTL_SECONDS: z.coerce.number().default(86400),
 
+    EXTERNAL_DEPLOYMENT_CACHE_REDIS_HOST: z
+      .string()
+      .optional()
+      .transform((v) => v ?? process.env.REDIS_HOST),
+    EXTERNAL_DEPLOYMENT_CACHE_REDIS_PORT: z.coerce
+      .number()
+      .optional()
+      .transform(
+        (v) => v ?? (process.env.REDIS_PORT ? parseInt(process.env.REDIS_PORT) : undefined)
+      ),
+    EXTERNAL_DEPLOYMENT_CACHE_REDIS_USERNAME: z
+      .string()
+      .optional()
+      .transform((v) => v ?? process.env.REDIS_USERNAME),
+    EXTERNAL_DEPLOYMENT_CACHE_REDIS_PASSWORD: z
+      .string()
+      .optional()
+      .transform((v) => v ?? process.env.REDIS_PASSWORD),
+    EXTERNAL_DEPLOYMENT_CACHE_REDIS_TLS_DISABLED: z
+      .string()
+      .default(process.env.REDIS_TLS_DISABLED ?? "false"),
+    EXTERNAL_DEPLOYMENT_CACHE_TTL_SECONDS: z.coerce.number().default(2592000),
+    EXTERNAL_DEPLOYMENT_PARK_DEADLINE_MS: z.coerce.number().default(3600000),
+
     // Runs-list empty-state check: how far back the ClickHouse "does this env have any run"
     // probe looks. Bounds the prove-absence partition scan. 0 = unbounded ("any run ever").
     RUN_LIST_HAS_RUNS_LOOKBACK_DAYS: z.coerce.number().default(30),
 
@@ -74,6 +74,9 @@ import {
 import { mollifyTrigger } from "~/v3/mollifier/mollifierMollify.server";
 import { QueueSizeLimitExceededError, ServiceValidationError } from "~/v3/services/common.server";
 import { runStore } from "~/v3/runStore.server";
+import type { ExternalDeploymentCache } from "~/services/externalDeploymentCache.server";
+import { externalDeploymentCacheInstance } from "~/services/externalDeploymentCacheInstance.server";
+import { resolveExternalDeployment } from "~/v3/services/resolveExternalDeployment.server";
 
 class NoopTriggerRacepointSystem implements TriggerRacepointSystem {
   async waitForRacepoint(options: { racepoint: TriggerRacepoints; id: string }): Promise<void> {
@@ -101,6 +104,7 @@ export class RunEngineTriggerTaskService {
   private readonly evaluateGate: MollifierEvaluateGate;
   private readonly getMollifierBuffer: MollifierGetBuffer;
   private readonly isMollifierGloballyEnabled: () => boolean;
+  private readonly externalDeploymentCache: ExternalDeploymentCache;
 
   constructor(opts: {
     prisma: PrismaClientOrTransaction;
@@ -117,6 +121,7 @@ export class RunEngineTriggerTaskService {
     evaluateGate?: MollifierEvaluateGate;
     getMollifierBuffer?: MollifierGetBuffer;
     isMollifierGloballyEnabled?: () => boolean;
+    externalDeploymentCache?: ExternalDeploymentCache;
   }) {
     this.prisma = opts.prisma;
     this.engine = opts.engine;
@@ -134,6 +139,7 @@ export class RunEngineTriggerTaskService {
     this.getMollifierBuffer = opts.getMollifierBuffer ?? defaultGetMollifierBuffer;
     this.isMollifierGloballyEnabled =
       opts.isMollifierGloballyEnabled ?? (() => env.TRIGGER_MOLLIFIER_ENABLED === "1");
+    this.externalDeploymentCache = opts.externalDeploymentCache ?? externalDeploymentCacheInstance;
   }
 
   /**
@@ -394,7 +400,7 @@ export class RunEngineTriggerTaskService {
             });
           }
 
-          const lockedToBackgroundWorker = body.options?.lockToVersion
+          const explicitlyLockedToBackgroundWorker = body.options?.lockToVersion
             ? await this.prisma.backgroundWorker.findFirst({
                 where: {
                   projectId: environment.projectId,
@@ -410,6 +416,34 @@ export class RunEngineTriggerTaskService {
               })
             : undefined;
 
+          const externalDeploymentId = body.options?.lockToVersion
+            ? undefined
+            : body.options?.externalDeploymentId;
+
+          const externalDeploymentResolution =
+            externalDeploymentId && environment.type !== "DEVELOPMENT"
+              ? await resolveExternalDeployment({
+                  prisma: this.prisma,
+                  environmentId: environment.id,
+                  externalDeploymentId,
+                  cache: this.externalDeploymentCache,
+                })
+              : undefined;
+
+          const lockedToBackgroundWorker =
+            explicitlyLockedToBackgroundWorker ??
+            (externalDeploymentResolution?.outcome === "deployed"
+              ? {
+                  id: externalDeploymentResolution.worker.workerId,
+                  version: externalDeploymentResolution.worker.version,
+                  sdkVersion: externalDeploymentResolution.worker.sdkVersion,
+                  cliVersion: externalDeploymentResolution.worker.cliVersion,
+                }
+              : undefined);
+
+          const parkedOnExternalDeploymentId =
+            externalDeploymentResolution?.outcome === "park" ? externalDeploymentId : undefined;
+
           const { queueName, lockedQueueId, taskTtl, taskKind } =
             await this.queueConcern.resolveQueueProperties(
               triggerRequest,
@@ -503,6 +537,7 @@ export class RunEngineTriggerTaskService {
             rootTriggerSource: parentAnnotations?.rootTriggerSource ?? triggerSource,
             rootScheduleId: parentAnnotations?.rootScheduleId || options.scheduleId || undefined,
             taskKind: taskKind ?? "STANDARD",
+            externalDeploymentId,
           };
 
           // Route runs in a scheduled lineage (the scheduled run itself and every
@@ -638,6 +673,7 @@ export class RunEngineTriggerTaskService {
                       depth,
                       parentRun: parentRun ?? undefined,
                       annotations,
+                      parkedOnExternalDeploymentId,
                       planType,
                       taskId,
                       payloadPacket,
@@ -717,6 +753,7 @@ export class RunEngineTriggerTaskService {
                   depth,
                   parentRun: parentRun ?? undefined,
                   annotations,
+                  parkedOnExternalDeploymentId,
                   planType,
                   taskId,
                   payloadPacket,
@@ -892,7 +929,9 @@ export class RunEngineTriggerTaskService {
       triggerAction: string;
       rootTriggerSource: string;
       rootScheduleId?: string | undefined;
+      externalDeploymentId?: string | undefined;
     };
+    parkedOnExternalDeploymentId?: string;
     planType?: string;
     taskId: string;
     payloadPacket: { data?: string; dataType: string };
@@ -974,6 +1013,7 @@ export class RunEngineTriggerTaskService {
       streamBasinName: args.environment.organization.streamBasinName,
       debounce: removeNullBytesFromKey(args.body.options?.debounce),
       annotations: args.annotations,
+      parkedOnExternalDeploymentId: args.parkedOnExternalDeploymentId,
     };
   }
 
 
@@ -0,0 +1,175 @@
+import type { Callback, Redis, Result } from "ioredis";
+import { logger } from "./logger.server";
+
+export type ExternalDeploymentCacheEntry = {
+  workerId: string;
+  version: string;
+  sdkVersion: string;
+  cliVersion: string;
+};
+
+export interface ExternalDeploymentCache {
+  get(environmentId: string, externalId: string): Promise<ExternalDeploymentCacheEntry | null>;
+  setIfNewer(
+    environmentId: string,
+    externalId: string,
+    entry: ExternalDeploymentCacheEntry
+  ): Promise<void>;
+}
+
+const KEY_PREFIX = "skewid:";
+
+const DEFAULT_TTL_SECONDS = 30 * 24 * 60 * 60;
+
+function buildKey(environmentId: string, externalId: string): string {
+  return `${KEY_PREFIX}${environmentId}:${externalId}`;
+}
+
+type CachedEntry = {
+  w: string;
+  v: string;
+  s: string;
+  c: string;
+};
+
+function encode(entry: ExternalDeploymentCacheEntry): string {
+  return JSON.stringify({
+    w: entry.workerId,
+    v: entry.version,
+    s: entry.sdkVersion,
+    c: entry.cliVersion,
+  } satisfies CachedEntry);
+}
+
+function decode(raw: string): ExternalDeploymentCacheEntry | null {
+  const parsed: unknown = JSON.parse(raw);
+
+  if (typeof parsed !== "object" || parsed === null) {
+    return null;
+  }
+
+  const { w, v, s, c } = parsed as Partial<CachedEntry>;
+
+  if (typeof w !== "string" || typeof v !== "string") {
+    return null;
+  }
+
+  return {
+    workerId: w,
+    version: v,
+    sdkVersion: typeof s === "string" ? s : "",
+    cliVersion: typeof c === "string" ? c : "",
+  };
+}
+
+const SET_IF_NEWER_LUA = `
+local existing = redis.call("GET", KEYS[1])
+
+if existing then
+  local ok, decoded = pcall(cjson.decode, existing)
+  if ok and type(decoded) == "table" and type(decoded.v) == "string" then
+    local existingDate, existingCounter = string.match(decoded.v, "^([^.]*)%.?(.*)$")
+    local incomingDate, incomingCounter = string.match(ARGV[2], "^([^.]*)%.?(.*)$")
+
+    if existingDate > incomingDate then
+      return 0
+    end
+
+    if existingDate == incomingDate then
+      if (tonumber(existingCounter) or 0) >= (tonumber(incomingCounter) or 0) then
+        return 0
+      end
+    end
+  end
+end
+
+redis.call("SET", KEYS[1], ARGV[1], "EX", tonumber(ARGV[3]))
+return 1
+`;
+
+declare module "ioredis" {
+  interface RedisCommander<Context> {
+    skewIdSetIfNewer(
+      key: string,
+      entry: string,
+      version: string,
+      ttlSeconds: string,
+      callback?: Callback<number>
+    ): Result<number, Context>;
+  }
+}
+
+export type RedisExternalDeploymentCacheOptions = {
+  redis: Redis;
+  ttlSeconds?: number;
+};
+
+export class RedisExternalDeploymentCache implements ExternalDeploymentCache {
+  private readonly redis: Redis;
+  private readonly ttlSeconds: number;
+
+  constructor(options: RedisExternalDeploymentCacheOptions) {
+    this.redis = options.redis;
+    this.ttlSeconds = options.ttlSeconds ?? DEFAULT_TTL_SECONDS;
+
+    this.redis.defineCommand("skewIdSetIfNewer", { numberOfKeys: 1, lua: SET_IF_NEWER_LUA });
+  }
+
+  async get(
+    environmentId: string,
+    externalId: string
+  ): Promise<ExternalDeploymentCacheEntry | null> {
+    try {
+      const raw = await this.redis.get(buildKey(environmentId, externalId));
+      if (!raw) return null;
+      return decode(raw);
+    } catch (error) {
+      logger.error("Failed to read external deployment resolution from cache", {
+        environmentId,
+        externalId,
+        error,
+      });
+      return null;
+    }
+  }
+
+  async setIfNewer(
+    environmentId: string,
+    externalId: string,
+    entry: ExternalDeploymentCacheEntry
+  ): Promise<void> {
+    try {
+      await this.redis.skewIdSetIfNewer(
+        buildKey(environmentId, externalId),
+        encode(entry),
+        entry.version,
+        String(this.ttlSeconds)
+      );
+    } catch (error) {
+      logger.error("Failed to write external deployment resolution to cache", {
+        environmentId,
+        externalId,
+        version: entry.version,
+        error,
+      });
+
+      try {
+        await this.redis.del(buildKey(environmentId, externalId));
+      } catch (deleteError) {
+        logger.error("Failed to evict stale external deployment resolution after write failure", {
+          environmentId,
+          externalId,
+          error: deleteError,
+        });
+      }
+    }
+  }
+}
+
+export class NoopExternalDeploymentCache implements ExternalDeploymentCache {
+  async get(): Promise<ExternalDeploymentCacheEntry | null> {
+    return null;
+  }
+
+  async setIfNewer(): Promise<void> {}
+}
@@ -0,0 +1,37 @@
+import { defaultReconnectOnError } from "@internal/redis";
+import Redis from "ioredis";
+import { env } from "~/env.server";
+import { singleton } from "~/utils/singleton";
+import {
+  type ExternalDeploymentCache,
+  NoopExternalDeploymentCache,
+  RedisExternalDeploymentCache,
+} from "./externalDeploymentCache.server";
+
+export const externalDeploymentCacheInstance: ExternalDeploymentCache = singleton(
+  "externalDeploymentCacheInstance",
+  initializeExternalDeploymentCache
+);
+
+function initializeExternalDeploymentCache(): ExternalDeploymentCache {
+  if (!env.EXTERNAL_DEPLOYMENT_CACHE_REDIS_HOST) {
+    return new NoopExternalDeploymentCache();
+  }
+
+  const redis = new Redis({
+    connectionName: "externalDeploymentCache",
+    host: env.EXTERNAL_DEPLOYMENT_CACHE_REDIS_HOST,
+    port: env.EXTERNAL_DEPLOYMENT_CACHE_REDIS_PORT,
+    username: env.EXTERNAL_DEPLOYMENT_CACHE_REDIS_USERNAME,
+    password: env.EXTERNAL_DEPLOYMENT_CACHE_REDIS_PASSWORD,
+    keyPrefix: "tr:",
+    enableAutoPipelining: true,
+    reconnectOnError: defaultReconnectOnError,
+    ...(env.EXTERNAL_DEPLOYMENT_CACHE_REDIS_TLS_DISABLED === "true" ? {} : { tls: {} }),
+  });
+
+  return new RedisExternalDeploymentCache({
+    redis,
+    ttlSeconds: env.EXTERNAL_DEPLOYMENT_CACHE_TTL_SECONDS,
+  });
+}