@photon-ai/linq

LinQ adapter for Spectrum.

• Inbound is delivered through Fusor (Spectrum's built-in inbound pipeline). Fusor hands the adapter the original raw request; the adapter verifies LinQ's webhook HMAC, parses the event, and produces Spectrum messages.
• Outbound uses LinQ's HTTP API via the official @linqapp/sdk.

LinQ is iMessage-native, so most of Spectrum's content model maps directly: text, attachments, voice memos, reactions (tapbacks), replies, rich links, message effects, typing indicators, group rename / icon, and contact cards.

Install

bun add @photon-ai/linq spectrum-ts@^12.7.0

Configure

Provision a bearer token and a webhook signing secret from your LinQ representative, then drop the provider into Spectrum({ providers: [...] }):

import { Spectrum, text } from "spectrum-ts";
import { linq } from "@photon-ai/linq";

const app = await Spectrum({
  projectId: process.env.PROJECT_ID,
  projectSecret: process.env.PROJECT_SECRET,
  providers: [
    linq.config({
      apiKey: process.env.LINQ_API_KEY,
      webhookSigningSecret: process.env.LINQ_WEBHOOK_SECRET,
      defaultFrom: "+12025550123", // optional: number for proactively-created chats
    }),
  ],
});

// Streaming
for await (const [space, message] of app.messages) {
  if (message.content.type === "text") {
    await space.send(text(`echo: ${message.content.text}`));
  }
}

Webhook mode

import {
  FusorJsonWebhookError,
  normalizeFusorWebhookRequest,
} from "@photon-ai/linq";

// Hono / Bun.serve / Next.js / Workers — pass the raw Request.
server.post("/webhooks/fusor", async (c) => {
  try {
    // Spectrum 12 consumes protobuf Fusor envelopes. This also accepts the
    // schema-v1 JSON envelope used by Fusor HTTP subscriptions and verifies
    // its outer signature when a secret is provided.
    const request = await normalizeFusorWebhookRequest(c.req.raw, {
      webhookSecret: process.env.SPECTRUM_WEBHOOK_SECRET,
    });
    return app.webhook(request, async (space, message) => {
      await space.send("got it");
    });
  } catch (error) {
    if (error instanceof FusorJsonWebhookError) {
      return new Response(error.message, { status: error.status });
    }
    throw error;
  }
});

The normalizer leaves protobuf Fusor deliveries and native Spectrum JSON webhooks untouched so app.webhook() can auto-detect them. If you also receive native Spectrum JSON, configure its separate Spectrum({ webhookSecret }).

Webhook signing

Inbound POSTs are verified in two independent layers:

Layer	Secret	Set on	Header(s)	Signed payload
Outer — JSON relay came from Fusor	webhookSecret	normalizeFusorWebhookRequest(...)	x-spectrum-signature / x-spectrum-timestamp	v0:{timestamp}: + raw body bytes, signature prefixed v0=
Inner — event came from LinQ	webhookSigningSecret	linq.config({...})	x-webhook-signature / x-webhook-timestamp	{timestamp}.{body}

Both use HMAC-SHA256 and are opt-in: when a secret is omitted, that layer's check is skipped. Set both in production — the outer secret proves the request reached you through the Fusor JSON relay, while the inner one proves the raw payload originated at LinQ. Spectrum's separate native JSON webhook uses Spectrum({ webhookSecret }) instead.

Only the inner LinQ layer is replay-guarded (replayToleranceSec); the outer Fusor layer intentionally does not enforce timestamp freshness, since Fusor retries can legitimately reuse an older sign-time.

Config

Field	Required	Default	Description
apiKey	yes	—	LinQ bearer token (outbound + media downloads).
webhookSigningSecret	recommended	—	Per-subscription HMAC secret. When set, inbound webhooks are verified (HMAC-SHA256 over {timestamp}.{body}) and replay-guarded. When omitted, verification is skipped.
defaultFrom	no	—	Provisioned phone number used when creating a new chat for a proactive send.
baseUrl	no	SDK default	Override the LinQ API base URL.
replayToleranceSec	no	300	Reject webhooks whose timestamp is older than this.

Content support

Spectrum content	LinQ
text	text part
attachment	upload → media part (attachment_id)
voice	voice-memo bubble
richlink	link part (sole part)
reply	threaded reply_to
effect	iMessage effect + inner part
reaction	tapback (or custom emoji)
typing	typing indicator
rename	group name update
avatar	group icon update
contact	shared as a .vcf media attachment
group	one message with multiple parts
custom	escape hatch (raw merged into the message body)
poll / poll_option	unsupported (LinQ has no polls) → UnsupportedError