Inngest Runtime Mapping

Recipe-only code sketch for mapping Crux runtime targets onto Inngest functions and events.

Inngest is a recipe and adapter-author target in v1, not a bundled Crux runtime package. The goal is to keep Crux authoring stable while an adapter maps wake delivery and retries onto Inngest infrastructure.

User-authored Crux targets

Users should still write Crux flows and durable tasks, not Inngest-specific functions.

import { flow } from "@use-crux/core/flow";
import { durableTask, type RuntimeTaskContext } from "@use-crux/core/runtime";

export const embedDocument = durableTask("embed-document", {
  run: async (input: { documentId: string }, _context: RuntimeTaskContext) => {
    const { documentId } = input;
    await embeddings.write(documentId);
  },
});

export const reviewFlow = flow(
  "review",
  async (flow, input: { documentId: string }) => {
    await flow.defer(embedDocument, { documentId: input.documentId });

    const approval = await flow.waitFor(
      { name: "document.approved" },
      { match: { documentId: input.documentId }, timeout: "24h" },
    );

    return approval;
  },
);

Wake bridge sketch

An Inngest-backed wake adapter can publish one event per Crux wake. Use the Crux idempotency key as the event id when the substrate supports it.

import { Inngest } from "inngest";
import type { RuntimeWakeAdapter } from "@use-crux/core/runtime";

const inngest = new Inngest({ id: "app" });

export function inngestWake(): RuntimeWakeAdapter {
  return {
    id: "inngest",
    capabilities: {
      signed: true,
      maxPayloadBytes: 4 * 1024,
      maxDelayMs: 7 * 24 * 60 * 60 * 1000,
    },
    createWake({ url }) {
      return async (envelope) => {
        await inngest.send({
          name: "crux/runtime.wake",
          id: envelope.idempotencyKey,
          data: {
            url,
            envelope,
          },
        });
      };
    },
  };
}

Inngest function sketch

The Inngest function acts as a delivery worker. It forwards the wake into the same fetch-compatible Crux handler used by generated serverless entries.

import { createRuntimeHandler } from "@use-crux/core/runtime";
import { embedDocument, reviewFlow } from "./targets";

const handler = createRuntimeHandler({
  targets: [reviewFlow, embedDocument],
});

export const cruxWake = inngest.createFunction(
  { id: "crux-runtime-wake" },
  { event: "crux/runtime.wake" },
  async ({ event, step }) => {
    const body = JSON.stringify(event.data.envelope);

    const response = await step.run("deliver-to-crux", () =>
      handler.POST(
        new Request(event.data.url, {
          method: "POST",
          body,
          headers: {
            "content-type": "application/json",
            // A real adapter should sign this request or bind directly without HTTP.
            "x-crux-signature": signCruxWake(body),
          },
        }),
      ),
    );

    if (response.status >= 500 || response.status === 409) {
      throw new Error(`Crux wake retryable status ${response.status}`);
    }
  },
);

Mapping notes

Runtime concern	Inngest substrate
Wake/tasks/timers/retries	Inngest functions, events, and steps
Event waits	Inngest wait-for-event style waits or Crux waiter state
State/events/leases	Crux store or adapter-owned Inngest-backed state

Do not split one invariant silently between Crux and Inngest. If Inngest owns retries or timers, the adapter must still surface Crux diagnostics such as TARGET_NOT_FOUND, REPLAY_DIVERGED, and WORK_DEAD_LETTERED.

Guide: Runtime Adapter Authoring
Reference: Runtime Engine

Inngest Runtime Mapping

User-authored Crux targets

Wake bridge sketch

Inngest function sketch

Mapping notes

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