hermes-agent/plugins/platforms/photon/sidecar/index.mjs

// Hermes Agent — Photon Spectrum sidecar
//
// Spawned by `plugins/platforms/photon/adapter.py` to bridge BOTH directions
// of messaging to Photon's Spectrum platform via the `spectrum-ts` SDK (the
// SDK is TypeScript-only, so a Node sidecar is unavoidable — there is no
// Python SDK and no public HTTP message API).
//
// Inbound  (gRPC -> Hermes): the SDK's `app.messages` async iterator is a
//   long-lived gRPC stream. We serialize each `[space, message]` to a
//   normalized JSON event and stream it to the Python adapter over a
//   loopback `GET /inbound` (NDJSON). We pause pulling from the stream while
//   no consumer is attached so a backlog isn't pulled-and-lost before the
//   gateway connects.
// Outbound (Hermes -> gRPC): `/send` and `/typing` drive `space.send(...)` /
//   `space.startTyping()` on the SDK.
//
// Protocol (all requests require `X-Hermes-Sidecar-Token: ${TOKEN}`):
//   - GET  /inbound    -> 200 NDJSON stream; one JSON event per line, blank
//                         lines are heartbeats. One consumer at a time.
//   - POST /healthz     -> {"ok": true}
//   - POST /send        -> {"ok": true, "messageId": "..."}
//       body: {"spaceId": "...", "text": "...", "replyTo": "..." | null}
//   - POST /send-attachment -> {"ok": true, "messageId": "..."}
//       body: {"spaceId": "...", "path": "...", "name": "..." | null,
//              "mimeType": "..." | null, "caption": "..." | null,
//              "kind": "attachment" | "voice", "replyTo": "..." | null}
//   - POST /typing      -> {"ok": true}
//       body: {"spaceId": "..."}
//   - POST /shutdown    -> {"ok": true}; then process exits
//
// On SIGINT/SIGTERM the sidecar calls `app.stop()` (3s graceful) before
// exiting. Logs go to stderr; Python supervises restart.
//
// Env vars (required):
//   PHOTON_PROJECT_ID      (== the project's spectrumProjectId)
//   PHOTON_PROJECT_SECRET
//   PHOTON_SIDECAR_PORT
//   PHOTON_SIDECAR_TOKEN
// Optional:
//   PHOTON_SIDECAR_BIND    (default 127.0.0.1)

import http from "node:http";
import { once } from "node:events";

const projectId = process.env.PHOTON_PROJECT_ID;
const projectSecret = process.env.PHOTON_PROJECT_SECRET;
const port = parseInt(process.env.PHOTON_SIDECAR_PORT || "8789", 10);
const bind = process.env.PHOTON_SIDECAR_BIND || "127.0.0.1";
const sharedToken = process.env.PHOTON_SIDECAR_TOKEN;

// Inbound attachments are read into memory and base64-inlined on the NDJSON
// event so the Python adapter can cache the real bytes (and the agent can see
// the image). Cap the size we inline — above it we forward metadata only and
// the adapter surfaces a text marker, so one large video can't balloon a
// single NDJSON line. Override via PHOTON_MAX_INLINE_ATTACHMENT_BYTES.
const MAX_INLINE_ATTACHMENT_BYTES =
  Number(process.env.PHOTON_MAX_INLINE_ATTACHMENT_BYTES) || 20 * 1024 * 1024;

if (!projectId || !projectSecret || !sharedToken) {
  console.error(
    "photon-sidecar: PHOTON_PROJECT_ID, PHOTON_PROJECT_SECRET and " +
      "PHOTON_SIDECAR_TOKEN must all be set."
  );
  process.exit(2);
}

// Lazy-load spectrum-ts so a missing install fails with a clear message
// instead of a cryptic module-resolution error during import.
let Spectrum, imessage, attachment, voice;
try {
  ({ Spectrum, attachment, voice } = await import("spectrum-ts"));
  ({ imessage } = await import("spectrum-ts/providers/imessage"));
} catch (e) {
  console.error(
    "photon-sidecar: spectrum-ts is not installed. Run `npm install` " +
      "inside plugins/platforms/photon/sidecar/. Original error: " +
      (e && e.stack ? e.stack : String(e))
  );
  process.exit(3);
}

const app = await Spectrum({
  projectId,
  projectSecret,
  providers: [imessage.config()],
});

// ---------------------------------------------------------------------------
// Inbound: forward `app.messages` (gRPC stream) to the Python consumer.

// At most one Python consumer is attached at a time (the gateway adapter).
let consumerRes = null;
let consumerWaiters = [];

function waitForConsumer() {
  if (consumerRes) return Promise.resolve();
  return new Promise((resolve) => consumerWaiters.push(resolve));
}

function setConsumer(res) {
  consumerRes = res;
  const waiters = consumerWaiters;
  consumerWaiters = [];
  for (const resolve of waiters) resolve();
}

function clearConsumer(res) {
  if (consumerRes === res) consumerRes = null;
}

// Write one NDJSON line to the active consumer. Blocks until a consumer is
// connected; if the write fails (consumer vanished mid-flight) we wait for a
// new consumer and retry, so a message is never silently dropped here.
async function deliver(line) {
  for (;;) {
    await waitForConsumer();
    const res = consumerRes;
    if (!res) continue;
    try {
      const flushed = res.write(line + "\n");
      if (!flushed) await once(res, "drain");
      return;
    } catch {
      clearConsumer(res);
    }
  }
}

async function normalizeContent(content) {
  if (!content || typeof content !== "object") {
    return { type: "unknown" };
  }
  if (content.type === "text") {
    return { type: "text", text: content.text || "" };
  }
  if (content.type === "attachment") {
    const meta = {
      type: "attachment",
      id: content.id ?? null,
      name: content.name ?? null,
      mimeType: content.mimeType ?? null,
      size: typeof content.size === "number" ? content.size : null,
    };
    // Read the bytes eagerly and base64-inline them as `data` so the Python
    // adapter can cache the real file (the agent then sees the image itself).
    // The spectrum-ts attachment object may not outlive this stream
    // iteration, so a lazy/on-demand fetch isn't safe. Over-cap attachments
    // (when size is known up front) are forwarded as metadata only and the
    // adapter falls back to a text marker. A read failure must never break
    // the inbound loop — we just drop `data` and forward metadata.
    if (meta.size !== null && meta.size > MAX_INLINE_ATTACHMENT_BYTES) {
      console.error(
        `photon-sidecar: attachment ${meta.name ?? meta.id} (${meta.size} bytes) ` +
          `exceeds inline cap ${MAX_INLINE_ATTACHMENT_BYTES}; forwarding metadata only`
      );
      return meta;
    }
    if (typeof content.read === "function") {
      try {
        const buf = await content.read();
        // Guard the case where size was unknown but the bytes turn out to be
        // over the cap.
        if (buf && buf.length > MAX_INLINE_ATTACHMENT_BYTES) {
          console.error(
            `photon-sidecar: attachment ${meta.name ?? meta.id} (${buf.length} bytes) ` +
              `exceeds inline cap after read; forwarding metadata only`
          );
          return meta;
        }
        meta.data = Buffer.from(buf).toString("base64");
        meta.encoding = "base64";
      } catch (e) {
        console.error(
          "photon-sidecar: failed to read attachment bytes " +
            "(forwarding metadata only): " +
            (e && e.stack ? e.stack : String(e))
        );
      }
    }
    return meta;
  }
  return { type: content.type || "unknown" };
}

async function normalizeEvent(space, message) {
  try {
    const msgSpace = message.space || {};
    const ts = message.timestamp;
    return {
      messageId: message.id ?? null,
      platform: message.platform || space.__platform || "iMessage",
      space: {
        id: space.id ?? msgSpace.id ?? null,
        // iMessage spaces carry `type` ("dm"|"group") and `phone` directly.
        type: space.type ?? msgSpace.type ?? "dm",
        phone: space.phone ?? msgSpace.phone ?? null,
      },
      sender: { id: message.sender ? message.sender.id : null },
      content: await normalizeContent(message.content),
      timestamp:
        ts instanceof Date ? ts.toISOString() : ts ? String(ts) : null,
    };
  } catch (e) {
    console.error(
      "photon-sidecar: failed to normalize inbound message: " + String(e)
    );
    return null;
  }
}

(async () => {
  try {
    for await (const [space, message] of app.messages) {
      // Only forward inbound messages (ignore our own outbound echoes).
      if (message && message.direction && message.direction !== "inbound") {
        continue;
      }
      const event = await normalizeEvent(space, message);
      if (!event) continue;
      await deliver(JSON.stringify(event));
    }
  } catch (e) {
    console.error(
      "photon-sidecar: inbound stream errored: " +
        (e && e.stack ? e.stack : String(e))
    );
  }
})();

// ---------------------------------------------------------------------------
// HTTP control + inbound server (loopback only).

async function readBody(req) {
  const chunks = [];
  for await (const chunk of req) chunks.push(chunk);
  const raw = Buffer.concat(chunks).toString("utf-8");
  if (!raw) return {};
  try {
    return JSON.parse(raw);
  } catch (e) {
    throw new Error("invalid JSON body");
  }
}

function unauthorized(res) {
  res.statusCode = 401;
  res.setHeader("Content-Type", "application/json");
  res.end(JSON.stringify({ ok: false, error: "unauthorized" }));
}

function badRequest(res, msg) {
  res.statusCode = 400;
  res.setHeader("Content-Type", "application/json");
  res.end(JSON.stringify({ ok: false, error: msg }));
}

function serverError(res) {
  res.statusCode = 500;
  res.setHeader("Content-Type", "application/json");
  // Don't leak stack traces or raw exception text to the caller — even
  // though we listen on loopback, the supervisor logs the real error
  // and the client only needs a generic failure signal.
  res.end(JSON.stringify({ ok: false, error: "internal sidecar error" }));
}

function ok(res, data) {
  res.statusCode = 200;
  res.setHeader("Content-Type", "application/json");
  res.end(JSON.stringify({ ok: true, ...data }));
}

function handleInbound(req, res) {
  res.statusCode = 200;
  res.setHeader("Content-Type", "application/x-ndjson");
  res.setHeader("Cache-Control", "no-store");
  res.setHeader("Connection", "keep-alive");
  // One consumer at a time — a fresh connection (e.g. after a reconnect)
  // supersedes the previous one.
  if (consumerRes && consumerRes !== res) {
    try {
      consumerRes.end();
    } catch {
      /* ignore */
    }
  }
  setConsumer(res);
  // Heartbeat keeps the socket warm through idle periods and lets the Python
  // side detect a dead pipe promptly.
  const heartbeat = setInterval(() => {
    try {
      res.write("\n");
    } catch {
      /* ignore */
    }
  }, 25000);
  const cleanup = () => {
    clearInterval(heartbeat);
    clearConsumer(res);
  };
  req.on("close", cleanup);
  req.on("aborted", cleanup);
  res.on("error", cleanup);
}

async function resolveSpace(spaceId) {
  // spectrum-ts exposes the same Space methods via `app.space(spaceId)` /
  // narrowed helpers; we fall back through a few accessor shapes to
  // tolerate small SDK API drift.
  if (typeof app.space === "function") {
    return await app.space(spaceId);
  }
  if (app.spaces && typeof app.spaces.get === "function") {
    return await app.spaces.get(spaceId);
  }
  if (imessage) {
    const im = imessage(app);
    if (typeof im.space === "function") {
      try {
        return await im.space({ id: spaceId });
      } catch {
        /* fall through */
      }
    }
  }
  throw new Error(`unable to resolve space id ${spaceId}`);
}

const server = http.createServer(async (req, res) => {
  if (req.headers["x-hermes-sidecar-token"] !== sharedToken) {
    return unauthorized(res);
  }
  // Long-lived inbound NDJSON stream.
  if (req.method === "GET" && req.url === "/inbound") {
    return handleInbound(req, res);
  }
  if (req.method !== "POST") {
    res.statusCode = 405;
    return res.end();
  }
  try {
    if (req.url === "/healthz") {
      return ok(res, {});
    }
    if (req.url === "/shutdown") {
      ok(res, {});
      setTimeout(() => process.kill(process.pid, "SIGTERM"), 50);
      return;
    }
    const body = await readBody(req);
    if (req.url === "/send") {
      const { spaceId, text, replyTo } = body || {};
      if (!spaceId || typeof text !== "string") {
        return badRequest(res, "spaceId and text are required");
      }
      const space = await resolveSpace(spaceId);
      const result = replyTo
        ? await space.send(text, { replyTo })
        : await space.send(text);
      return ok(res, { messageId: result?.id || result?.messageId || null });
    }
    if (req.url === "/send-attachment") {
      const { spaceId, path, name, mimeType, caption, kind, replyTo } =
        body || {};
      if (!spaceId || typeof path !== "string" || !path) {
        return badRequest(res, "spaceId and path are required");
      }
      const space = await resolveSpace(spaceId);

      // spectrum-ts infers name + MIME from the file extension; pass
      // overrides only when Hermes supplied them so a known-good
      // inference isn't clobbered with an empty string.
      const opts = {};
      if (name) opts.name = name;
      if (mimeType) opts.mimeType = mimeType;
      const builder =
        kind === "voice"
          ? voice(path, Object.keys(opts).length ? opts : undefined)
          : attachment(path, Object.keys(opts).length ? opts : undefined);

      const sendOpts = replyTo ? { replyTo } : undefined;
      const result = sendOpts
        ? await space.send(builder, sendOpts)
        : await space.send(builder);

      // iMessage delivers the caption as a separate bubble; send it
      // after the media so the attachment renders first.
      if (caption && typeof caption === "string") {
        try {
          await space.send(caption);
        } catch (e) {
          console.error(
            "photon-sidecar: attachment sent but caption failed: " +
              (e && e.stack ? e.stack : String(e))
          );
        }
      }
      return ok(res, { messageId: result?.id || result?.messageId || null });
    }
    if (req.url === "/typing") {
      const { spaceId } = body || {};
      if (!spaceId) return badRequest(res, "spaceId is required");
      const space = await resolveSpace(spaceId);
      if (typeof space.startTyping === "function") {
        await space.startTyping();
      } else if (typeof space.typing === "function") {
        await space.typing();
      } else if (typeof space.setTyping === "function") {
        await space.setTyping(true);
      }
      return ok(res, {});
    }
    res.statusCode = 404;
    res.setHeader("Content-Type", "application/json");
    return res.end(JSON.stringify({ ok: false, error: "not found" }));
  } catch (e) {
    console.error(
      "photon-sidecar: handler error: " +
        (e && e.stack ? e.stack : String(e))
    );
    // serverError() intentionally returns a generic message — see its
    // body for the rationale.
    return serverError(res);
  }
});

server.listen(port, bind, () => {
  console.error(`photon-sidecar: listening on ${bind}:${port}`);
});

async function shutdown(signal) {
  console.error(`photon-sidecar: received ${signal}, stopping...`);
  try {
    await Promise.race([
      app.stop(),
      new Promise((resolve) => setTimeout(resolve, 3000)),
    ]);
  } catch (e) {
    console.error("photon-sidecar: app.stop() failed: " + String(e));
  }
  server.close(() => process.exit(0));
  setTimeout(() => process.exit(1), 500).unref();
}

process.on("SIGINT", () => shutdown("SIGINT"));
process.on("SIGTERM", () => shutdown("SIGTERM"));