feat(photon): wire outbound media via spectrum-ts attachment() (#42397)

Photon now exposes attachment send (Ray Sun, photon-nousresearch), so
the Photon plugin gains outbound media to match the BlueBubbles iMessage
channel.

- sidecar: new /send-attachment endpoint wrapping space.send(attachment())
  / space.send(voice()); caption sent as a trailing text bubble.
- adapter: override send_image/send_image_file/send_voice/send_video/
  send_document/send_animation. URL helpers cache to a local path first
  (cache_image_from_url), file helpers pass through. Defense-in-depth
  path re-validation before the path reaches the Node sidecar.
- _standalone_send (cron): send text first, then each media_file as a
  /send-attachment call (is_voice -> voice builder).
- docs/README: flip the 'outbound attachments not wired' note.

plugins/platforms/photon/README.md

@@ -106,14 +106,16 @@ All env vars are documented in `plugin.yaml`. The most important are:
 
 ## Limitations (current Photon API)
 
-- **Attachments are metadata only.** Inbound webhooks include the
+- **Inbound attachments are metadata only.** Inbound webhooks include the
   filename + MIME type but no download URL. The plugin surfaces a
   text marker (`[Photon attachment received: …]`) so the agent knows
   something arrived, but cannot read the bytes.  Photon's docs note
   an attachment retrieval endpoint is on the roadmap.
-- **Outbound attachments are not supported yet.** Adding them is
-  straightforward once the sidecar wires up `attachment(...)` /
-  `space.send(attachment(...))` from `spectrum-ts`.
+- **Outbound attachments are supported.** Images, voice notes, video,
+  and documents are sent via `space.send(attachment(...))` /
+  `space.send(voice(...))` through the sidecar's `/send-attachment`
+  endpoint. A caption is delivered as a separate text bubble after the
+  media.
 - **Reactions, message effects, polls** — not exposed yet; the
   `spectrum-ts` SDK supports them, and the sidecar is the natural
   place to add them when the agent has reason to use them.

plugins/platforms/photon/adapter.py

@@ -14,8 +14,10 @@ Outbound:
     Photon does not currently expose a public HTTP send-message
     endpoint, so the adapter spawns a small Node sidecar (see
     ``sidecar/index.mjs``) that runs the ``spectrum-ts`` SDK.  Each
-    ``send`` / ``send_typing`` call from Hermes is a loopback POST to
-    the sidecar with a shared bearer token.
+    ``send`` / ``send_typing`` / attachment call from Hermes is a
+    loopback POST to the sidecar with a shared bearer token.  Outbound
+    media (images, voice notes, video, documents) goes through
+    spectrum-ts' ``attachment()`` / ``voice()`` content builders.
 
 When Photon ships an HTTP send endpoint we can collapse the sidecar
 into ``_send_via_http`` and drop the Node dependency entirely.
@@ -670,6 +672,99 @@ class PhotonAdapter(BasePlatformAdapter):
     ) -> SendResult:
         return await self._sidecar_send(chat_id, content, reply_to=reply_to)
 
+    # -- Outbound media (parity with the BlueBubbles iMessage channel) -----
+    #
+    # Photon ships outbound attachments via spectrum-ts' `attachment()` /
+    # `voice()` content builders. The sidecar's `/send-attachment` endpoint
+    # wraps `space.send(attachment(path, {...}))`. These overrides mirror
+    # BlueBubbles: URL-based helpers cache to a local path first, file-based
+    # helpers pass the path straight through.
+
+    async def send_image(
+        self,
+        chat_id: str,
+        image_url: str,
+        caption: Optional[str] = None,
+        reply_to: Optional[str] = None,
+        metadata: Optional[Dict[str, Any]] = None,
+    ) -> SendResult:
+        try:
+            from gateway.platforms.base import cache_image_from_url
+
+            local_path = await cache_image_from_url(image_url)
+        except Exception:
+            # Couldn't fetch the URL — fall back to sending it as text.
+            return await super().send_image(chat_id, image_url, caption, reply_to)
+        return await self._sidecar_send_attachment(
+            chat_id, local_path, caption=caption, reply_to=reply_to,
+        )
+
+    async def send_image_file(
+        self,
+        chat_id: str,
+        image_path: str,
+        caption: Optional[str] = None,
+        reply_to: Optional[str] = None,
+        metadata: Optional[Dict[str, Any]] = None,
+        **kwargs,
+    ) -> SendResult:
+        return await self._sidecar_send_attachment(
+            chat_id, image_path, caption=caption, reply_to=reply_to,
+        )
+
+    async def send_voice(
+        self,
+        chat_id: str,
+        audio_path: str,
+        caption: Optional[str] = None,
+        reply_to: Optional[str] = None,
+        metadata: Optional[Dict[str, Any]] = None,
+        **kwargs,
+    ) -> SendResult:
+        return await self._sidecar_send_attachment(
+            chat_id, audio_path, caption=caption, reply_to=reply_to, kind="voice",
+        )
+
+    async def send_video(
+        self,
+        chat_id: str,
+        video_path: str,
+        caption: Optional[str] = None,
+        reply_to: Optional[str] = None,
+        metadata: Optional[Dict[str, Any]] = None,
+        **kwargs,
+    ) -> SendResult:
+        return await self._sidecar_send_attachment(
+            chat_id, video_path, caption=caption, reply_to=reply_to,
+        )
+
+    async def send_document(
+        self,
+        chat_id: str,
+        file_path: str,
+        caption: Optional[str] = None,
+        file_name: Optional[str] = None,
+        reply_to: Optional[str] = None,
+        metadata: Optional[Dict[str, Any]] = None,
+        **kwargs,
+    ) -> SendResult:
+        return await self._sidecar_send_attachment(
+            chat_id, file_path, name=file_name, caption=caption, reply_to=reply_to,
+        )
+
+    async def send_animation(
+        self,
+        chat_id: str,
+        animation_url: str,
+        caption: Optional[str] = None,
+        reply_to: Optional[str] = None,
+        metadata: Optional[Dict[str, Any]] = None,
+    ) -> SendResult:
+        # iMessage renders GIFs inline as ordinary image attachments.
+        return await self.send_image(
+            chat_id, animation_url, caption, reply_to, metadata,
+        )
+
     async def send_typing(self, chat_id: str, metadata=None) -> None:
         try:
             await self._sidecar_call("/typing", {"spaceId": chat_id})
@@ -704,6 +799,57 @@ class PhotonAdapter(BasePlatformAdapter):
             return SendResult(success=False, error=str(e))
         return SendResult(success=True, message_id=data.get("messageId"))
 
+    async def _sidecar_send_attachment(
+        self,
+        space_id: str,
+        path: str,
+        *,
+        name: Optional[str] = None,
+        mime_type: Optional[str] = None,
+        caption: Optional[str] = None,
+        reply_to: Optional[str] = None,
+        kind: str = "attachment",
+    ) -> SendResult:
+        """POST a local file to the sidecar's ``/send-attachment`` endpoint.
+
+        ``kind`` is ``"voice"`` for audio sent as a voice note (downgrades
+        to a plain audio attachment on platforms without voice notes),
+        otherwise ``"attachment"``. spectrum-ts infers ``name`` and
+        ``mimeType`` from the file extension; we only pass overrides when
+        Hermes supplied them.
+        """
+        # Defense-in-depth: re-validate the path before handing it to the
+        # Node sidecar. The gateway already filters MEDIA paths, but
+        # send_*_file / cron callers may pass arbitrary strings.
+        safe_path = self.validate_media_delivery_path(str(path))
+        if not safe_path:
+            return SendResult(
+                success=False, error=f"unsafe or missing attachment path: {path}"
+            )
+        if not mime_type:
+            import mimetypes
+
+            guessed, _ = mimetypes.guess_type(safe_path)
+            mime_type = guessed or None
+        body: Dict[str, Any] = {
+            "spaceId": space_id,
+            "path": safe_path,
+            "kind": "voice" if kind == "voice" else "attachment",
+        }
+        if name:
+            body["name"] = name
+        if mime_type:
+            body["mimeType"] = mime_type
+        if caption:
+            body["caption"] = caption
+        if reply_to:
+            body["replyTo"] = reply_to
+        try:
+            data = await self._sidecar_call("/send-attachment", body)
+        except Exception as e:
+            return SendResult(success=False, error=str(e))
+        return SendResult(success=True, message_id=data.get("messageId"))
+
     async def _sidecar_call(self, path: str, body: Dict[str, Any]) -> Dict[str, Any]:
         if self._http_client is None:
             raise RuntimeError("Photon adapter not connected")
@@ -753,8 +899,8 @@ async def _standalone_send(
     message: str,
     *,
     thread_id: Optional[str] = None,  # noqa: ARG001 — Spectrum has no threads yet
-    media_files: Optional[list] = None,  # noqa: ARG001 — attachment send not supported yet
-    force_document: bool = False,  # noqa: ARG001
+    media_files: Optional[list] = None,
+    force_document: bool = False,  # noqa: ARG001 — iMessage auto-detects file kind
 ) -> Dict[str, Any]:
     if not HTTPX_AVAILABLE:
         return {"error": "httpx not installed"}
@@ -771,20 +917,54 @@ async def _standalone_send(
                 "cannot spawn the sidecar themselves."
             )
         }
-    body: Dict[str, Any] = {"spaceId": chat_id, "text": message[:_MAX_MESSAGE_LENGTH]}
+    base = f"http://{_DEFAULT_SIDECAR_BIND}:{port}"
+    headers = {"X-Hermes-Sidecar-Token": token}
+    last_message_id: Optional[str] = None
     try:
         async with httpx.AsyncClient(timeout=30.0) as client:
-            resp = await client.post(
-                f"http://{_DEFAULT_SIDECAR_BIND}:{port}/send",
-                json=body,
-                headers={"X-Hermes-Sidecar-Token": token},
-            )
-        if resp.status_code != 200:
-            return {"error": f"sidecar returned {resp.status_code}: {resp.text[:200]}"}
-        data = resp.json() or {}
-        if not data.get("ok"):
-            return {"error": data.get("error") or "sidecar reported failure"}
-        return {"success": True, "message_id": data.get("messageId")}
+            # 1. Text body first (if any), so it leads the conversation.
+            if message:
+                resp = await client.post(
+                    f"{base}/send",
+                    json={"spaceId": chat_id, "text": message[:_MAX_MESSAGE_LENGTH]},
+                    headers=headers,
+                )
+                if resp.status_code != 200:
+                    return {"error": f"sidecar returned {resp.status_code}: {resp.text[:200]}"}
+                data = resp.json() or {}
+                if not data.get("ok"):
+                    return {"error": data.get("error") or "sidecar reported failure"}
+                last_message_id = data.get("messageId")
+
+            # 2. Each attachment as a separate /send-attachment call.
+            #    media_files is List[Tuple[path, is_voice]] (see
+            #    BasePlatformAdapter.filter_media_delivery_paths).
+            import mimetypes
+
+            for media_path, is_voice in media_files or []:
+                safe_path = BasePlatformAdapter.validate_media_delivery_path(str(media_path))
+                if not safe_path:
+                    logger.warning("[photon] standalone send skipping unsafe path")
+                    continue
+                guessed, _ = mimetypes.guess_type(safe_path)
+                att_body: Dict[str, Any] = {
+                    "spaceId": chat_id,
+                    "path": safe_path,
+                    "kind": "voice" if is_voice else "attachment",
+                }
+                if guessed:
+                    att_body["mimeType"] = guessed
+                resp = await client.post(
+                    f"{base}/send-attachment", json=att_body, headers=headers,
+                )
+                if resp.status_code != 200:
+                    return {"error": f"sidecar returned {resp.status_code}: {resp.text[:200]}"}
+                data = resp.json() or {}
+                if not data.get("ok"):
+                    return {"error": data.get("error") or "sidecar reported failure"}
+                last_message_id = data.get("messageId") or last_message_id
+
+        return {"success": True, "message_id": last_message_id}
     except Exception as e:
         return {"error": f"Photon standalone send failed: {e}"}
 

plugins/platforms/photon/sidecar/index.mjs

@@ -12,6 +12,10 @@
 //   - 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
@@ -48,9 +52,9 @@ if (!projectId || !projectSecret || !sharedToken) {
 
 // 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;
+let Spectrum, imessage, attachment, voice;
 try {
-  ({ Spectrum } = await import("spectrum-ts"));
+  ({ Spectrum, attachment, voice } = await import("spectrum-ts"));
   ({ imessage } = await import("spectrum-ts/providers/imessage"));
 } catch (e) {
   console.error(
@@ -179,6 +183,44 @@ const server = http.createServer(async (req, res) => {
         : 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");

tests/plugins/platforms/photon/test_outbound_media.py

@@ -0,0 +1,255 @@
+"""Outbound-media tests for PhotonAdapter.
+
+Photon ships outbound attachments via spectrum-ts' ``attachment()`` /
+``voice()`` content builders, reached through the Node sidecar's
+``/send-attachment`` endpoint. These tests stub ``_sidecar_call`` so we
+can assert the endpoint + body shape each ``send_*`` override produces
+without spawning Node or binding ports.
+"""
+from __future__ import annotations
+
+import os
+from typing import Any, Dict, List, Tuple
+
+import pytest
+
+from gateway.config import PlatformConfig
+from plugins.platforms.photon import adapter as photon_adapter
+from plugins.platforms.photon.adapter import PhotonAdapter
+
+
+def _make_adapter(monkeypatch: pytest.MonkeyPatch) -> PhotonAdapter:
+    monkeypatch.setenv("PHOTON_PROJECT_ID", "test-project-id")
+    monkeypatch.setenv("PHOTON_PROJECT_SECRET", "test-project-secret")
+    monkeypatch.delenv("PHOTON_WEBHOOK_SECRET", raising=False)
+    cfg = PlatformConfig(enabled=True, token="", extra={})
+    return PhotonAdapter(cfg)
+
+
+def _capture_sidecar(adapter: PhotonAdapter) -> List[Tuple[str, Dict[str, Any]]]:
+    """Replace ``_sidecar_call`` with a recorder that returns a fixed id."""
+    calls: List[Tuple[str, Dict[str, Any]]] = []
+
+    async def _fake_call(path: str, body: Dict[str, Any]) -> Dict[str, Any]:
+        calls.append((path, body))
+        return {"ok": True, "messageId": "msg-123"}
+
+    adapter._sidecar_call = _fake_call  # type: ignore[assignment]
+    return calls
+
+
+@pytest.fixture()
+def real_file(tmp_path) -> str:
+    p = tmp_path / "photo.jpg"
+    p.write_bytes(b"\xff\xd8\xff\xe0fake-jpeg")
+    return str(p)
+
+
+def _patch_safe_path(monkeypatch: pytest.MonkeyPatch) -> None:
+    """Make path validation a passthrough so tmp files outside the cache pass."""
+    monkeypatch.setattr(
+        PhotonAdapter,
+        "validate_media_delivery_path",
+        staticmethod(lambda p: p if os.path.exists(p) else None),
+    )
+
+
+@pytest.mark.asyncio
+async def test_send_image_file_hits_attachment_endpoint(
+    monkeypatch: pytest.MonkeyPatch, real_file: str
+) -> None:
+    _patch_safe_path(monkeypatch)
+    adapter = _make_adapter(monkeypatch)
+    calls = _capture_sidecar(adapter)
+
+    result = await adapter.send_image_file(
+        "any;-;+15551234567", real_file, caption="look"
+    )
+
+    assert result.success is True
+    assert result.message_id == "msg-123"
+    assert len(calls) == 1
+    path, body = calls[0]
+    assert path == "/send-attachment"
+    assert body["spaceId"] == "any;-;+15551234567"
+    assert body["path"] == real_file
+    assert body["kind"] == "attachment"
+    assert body["caption"] == "look"
+    assert body["mimeType"] == "image/jpeg"  # inferred from .jpg
+
+
+@pytest.mark.asyncio
+async def test_send_voice_marks_kind_voice(
+    monkeypatch: pytest.MonkeyPatch, tmp_path
+) -> None:
+    _patch_safe_path(monkeypatch)
+    audio = tmp_path / "note.m4a"
+    audio.write_bytes(b"fake-audio")
+    adapter = _make_adapter(monkeypatch)
+    calls = _capture_sidecar(adapter)
+
+    result = await adapter.send_voice("any;-;+1", str(audio))
+
+    assert result.success is True
+    path, body = calls[0]
+    assert path == "/send-attachment"
+    assert body["kind"] == "voice"
+
+
+@pytest.mark.asyncio
+async def test_send_document_passes_filename(
+    monkeypatch: pytest.MonkeyPatch, tmp_path
+) -> None:
+    _patch_safe_path(monkeypatch)
+    doc = tmp_path / "report.pdf"
+    doc.write_bytes(b"%PDF-1.4 fake")
+    adapter = _make_adapter(monkeypatch)
+    calls = _capture_sidecar(adapter)
+
+    await adapter.send_document("any;-;+1", str(doc), file_name="Q3.pdf")
+
+    _, body = calls[0]
+    assert body["kind"] == "attachment"
+    assert body["name"] == "Q3.pdf"
+    assert body["mimeType"] == "application/pdf"
+
+
+@pytest.mark.asyncio
+async def test_send_video_passes_through(
+    monkeypatch: pytest.MonkeyPatch, tmp_path
+) -> None:
+    _patch_safe_path(monkeypatch)
+    vid = tmp_path / "clip.mp4"
+    vid.write_bytes(b"fake-mp4")
+    adapter = _make_adapter(monkeypatch)
+    calls = _capture_sidecar(adapter)
+
+    await adapter.send_video("any;+;groupguid", str(vid), caption="watch")
+
+    _, body = calls[0]
+    assert body["kind"] == "attachment"
+    assert body["caption"] == "watch"
+
+
+@pytest.mark.asyncio
+async def test_send_image_url_caches_then_sends_attachment(
+    monkeypatch: pytest.MonkeyPatch, real_file: str
+) -> None:
+    _patch_safe_path(monkeypatch)
+    adapter = _make_adapter(monkeypatch)
+    calls = _capture_sidecar(adapter)
+
+    async def _fake_cache(url: str, *a, **k) -> str:
+        assert url == "https://example.com/cat.jpg"
+        return real_file
+
+    import gateway.platforms.base as base_mod
+
+    monkeypatch.setattr(base_mod, "cache_image_from_url", _fake_cache)
+
+    result = await adapter.send_image(
+        "any;-;+1", "https://example.com/cat.jpg", caption="cat"
+    )
+
+    assert result.success is True
+    path, body = calls[0]
+    assert path == "/send-attachment"
+    assert body["path"] == real_file
+    assert body["caption"] == "cat"
+
+
+@pytest.mark.asyncio
+async def test_send_image_url_fetch_failure_falls_back_to_text(
+    monkeypatch: pytest.MonkeyPatch
+) -> None:
+    adapter = _make_adapter(monkeypatch)
+    calls = _capture_sidecar(adapter)
+
+    async def _boom(url: str, *a, **k) -> str:
+        raise RuntimeError("network down")
+
+    import gateway.platforms.base as base_mod
+
+    monkeypatch.setattr(base_mod, "cache_image_from_url", _boom)
+
+    result = await adapter.send_image(
+        "any;-;+1", "https://example.com/cat.jpg", caption="cat"
+    )
+
+    # Fallback path: base send_image() routes to send() → /send (text).
+    assert result.success is True
+    assert calls[0][0] == "/send"
+    assert "https://example.com/cat.jpg" in calls[0][1]["text"]
+
+
+@pytest.mark.asyncio
+async def test_send_attachment_rejects_unsafe_path(
+    monkeypatch: pytest.MonkeyPatch
+) -> None:
+    # Default validation (no passthrough patch) should reject a nonexistent /
+    # traversal path, returning a failed SendResult without calling the sidecar.
+    monkeypatch.setattr(
+        PhotonAdapter,
+        "validate_media_delivery_path",
+        staticmethod(lambda p: None),
+    )
+    adapter = _make_adapter(monkeypatch)
+    calls = _capture_sidecar(adapter)
+
+    result = await adapter.send_image_file("any;-;+1", "/etc/passwd")
+
+    assert result.success is False
+    assert "unsafe" in (result.error or "")
+    assert calls == []  # never reached the sidecar
+
+
+@pytest.mark.asyncio
+async def test_standalone_send_text_then_attachments(
+    monkeypatch: pytest.MonkeyPatch, tmp_path
+) -> None:
+    _patch_safe_path(monkeypatch)
+    img = tmp_path / "a.png"
+    img.write_bytes(b"\x89PNG fake")
+    monkeypatch.setenv("PHOTON_SIDECAR_TOKEN", "tok")
+
+    posted: List[Tuple[str, Dict[str, Any]]] = []
+
+    class _Resp:
+        status_code = 200
+
+        @staticmethod
+        def json() -> Dict[str, Any]:
+            return {"ok": True, "messageId": "m-9"}
+
+    class _FakeClient:
+        def __init__(self, *a, **k):
+            pass
+
+        async def __aenter__(self):
+            return self
+
+        async def __aexit__(self, *a):
+            return False
+
+        async def post(self, url: str, json: Dict[str, Any], headers=None):
+            posted.append((url, json))
+            return _Resp()
+
+    monkeypatch.setattr(photon_adapter.httpx, "AsyncClient", _FakeClient)
+
+    cfg = PlatformConfig(enabled=True, token="", extra={})
+    result = await photon_adapter._standalone_send(
+        cfg,
+        "any;-;+1",
+        "hello",
+        media_files=[(str(img), False)],
+    )
+
+    assert result.get("success") is True
+    # First call is the text /send, second is /send-attachment.
+    assert posted[0][0].endswith("/send")
+    assert posted[0][1]["text"] == "hello"
+    assert posted[1][0].endswith("/send-attachment")
+    assert posted[1][1]["path"] == str(img)
+    assert posted[1][1]["kind"] == "attachment"
+    assert posted[1][1]["mimeType"] == "image/png"

website/docs/user-guide/messaging/photon.md

@@ -206,11 +206,14 @@ hermes photon webhook delete <webhook-id>   # remove one
 
 ## Limits today
 
-- **Attachments are metadata-only.** Inbound webhooks carry the
+- **Inbound attachments are metadata-only.** Inbound webhooks carry the
   filename + MIME type but no download URL — Photon documents an
   attachment retrieval endpoint as roadmap.
-- **Outbound attachments not wired yet.** Easy to add in the sidecar
-  once the agent has reason to send them.
+- **Outbound attachments are supported.** Hermes sends images, voice
+  notes, video, and documents through spectrum-ts' `attachment()` /
+  `voice()` content builders via the sidecar's `/send-attachment`
+  endpoint. Captions arrive as a separate iMessage bubble after the
+  media.
 - **Photon's free quotas:** 5,000 messages per server per day,
   50 new-conversation initiations per shared line per day. Increases
   available — email `help@photon.codes`.