diff --git a/plugins/platforms/photon/sidecar/index.mjs b/plugins/platforms/photon/sidecar/index.mjs
index ee2620c5877f7..1bc9ac96e9fd3 100644
--- a/plugins/platforms/photon/sidecar/index.mjs
+++ b/plugins/platforms/photon/sidecar/index.mjs
@@ -848,8 +848,16 @@ const server = http.createServer(async (req, res) => {
       const space = await resolveSpace(spaceId);
       // iMessage renders markdown natively; spectrum-ts degrades it to
       // readable plain text on platforms that don't.
+      // spectrumMarkdown() enables enableDataDetection in the underlying
+      // iMessage API, which can 500 on messages containing raw URLs.
+      // Plain-text URLs are auto-linked by iMessage, so route markdown
+      // messages that contain URLs through spectrumText while preserving
+      // spectrumMarkdown for URL-free markdown.
+      const hasUrl = /https?:\/\/[^\s)'"<>]+/i.test(text);
       const builder =
-        format === "markdown" ? spectrumMarkdown(text) : spectrumText(text);
+        format === "markdown" && !hasUrl
+          ? spectrumMarkdown(text)
+          : spectrumText(text);
       const result = await space.send(builder);
       return ok(res, { messageId: result?.id || null });
     }
diff --git a/tests/plugins/platforms/photon/test_url_send_path.py b/tests/plugins/platforms/photon/test_url_send_path.py
new file mode 100644
index 0000000000000..f3bfd81b2c165
--- /dev/null
+++ b/tests/plugins/platforms/photon/test_url_send_path.py
@@ -0,0 +1,50 @@
+"""Regression tests for Photon raw-URL message delivery.
+
+The iMessage markdown builder enables data detection inside spectrum-ts. On
+some IMAgentKit sends, that path returns a 500 when the message contains a raw
+URL. The sidecar should keep markdown rendering for URL-free messages, but use
+plain text for messages containing URLs so iMessage can auto-link them without
+hitting the data-detection failure path.
+"""
+
+from __future__ import annotations
+
+import re
+from pathlib import Path
+
+
+SIDECAR = Path("plugins/platforms/photon/sidecar/index.mjs")
+
+
+def _source() -> str:
+    return SIDECAR.read_text(encoding="utf-8")
+
+
+def test_photon_sidecar_detects_raw_urls_before_builder_selection() -> None:
+    src = _source()
+
+    assert "hasUrl" in src
+    assert "https?:\\/\\/" in src
+    assert re.search(r"const\s+hasUrl\s*=\s*/https\?:", src)
+
+
+def test_markdown_builder_is_used_only_for_url_free_markdown() -> None:
+    src = _source()
+
+    assert re.search(
+        r'format\s*===\s*["\']markdown["\']\s*&&\s*!hasUrl',
+        src,
+    )
+    assert "spectrumMarkdown(text)" in src
+
+
+def test_text_builder_is_fallback_for_markdown_messages_with_urls() -> None:
+    src = _source()
+
+    # Builder selection must still have spectrumText as the fallback branch so
+    # markdown+URL messages avoid spectrumMarkdown's data-detection path.
+    assert "spectrumText(text)" in src
+    assert re.search(
+        r'format\s*===\s*["\']markdown["\']\s*&&\s*!hasUrl[\s\S]*\?[\s\S]*spectrumMarkdown\(text\)[\s\S]*:[\s\S]*spectrumText\(text\)',
+        src,
+    )