diff --git a/api/config.py b/api/config.py
index 0eb26136..44d18b9d 100644
--- a/api/config.py
+++ b/api/config.py
@@ -1046,6 +1046,7 @@ MIME_MAP = {
     ".ico": "image/x-icon",
     ".bmp": "image/bmp",
     ".pdf": "application/pdf",
+    ".zip": "application/zip",
     ".json": "application/json",
     ".html": "text/html",
     ".htm": "text/html",
diff --git a/api/routes.py b/api/routes.py
index 4cdb91c5..b975fd21 100644
--- a/api/routes.py
+++ b/api/routes.py
@@ -20775,7 +20775,12 @@ def _handle_media(handler, parsed):
         "video/mp4", "video/quicktime", "video/webm", "video/ogg",
         "application/pdf",
     }
-    _SESSION_MEDIA_TOKEN_TYPES = _INLINE_IMAGE_TYPES | _AUDIO_VIDEO_PDF_TYPES | {"text/html"}
+    # Archives are download-only: never added to the inline-preview sets below,
+    # so they always get Content-Disposition: attachment.
+    _ARCHIVE_TYPES = {"application/zip"}
+    _SESSION_MEDIA_TOKEN_TYPES = (
+        _INLINE_IMAGE_TYPES | _AUDIO_VIDEO_PDF_TYPES | _ARCHIVE_TYPES | {"text/html"}
+    )
     session_media_allowed = _session_media_token_allows_path(
         qs.get("session_id", [""])[0],
         target,
diff --git a/tests/test_zip_media_delivery.py b/tests/test_zip_media_delivery.py
new file mode 100644
index 00000000..dfd9ec2f
--- /dev/null
+++ b/tests/test_zip_media_delivery.py
@@ -0,0 +1,93 @@
+"""Tests for zip archive delivery through /api/media.
+
+Archives previously resolved to application/octet-stream (``.zip`` was absent
+from ``MIME_MAP``) and were therefore rejected by the session MEDIA: token
+allow-list, so a ``MEDIA:/path/to/file.zip`` link always failed to open.
+
+Covers:
+1. ``.zip`` maps to ``application/zip`` in MIME_MAP
+2. ``application/zip`` is accepted by the session MEDIA: token allow-list
+3. ``application/zip`` is NOT an inline-preview type (must download, never render)
+"""
+from __future__ import annotations
+
+import pathlib
+import re
+import unittest
+
+REPO_ROOT = pathlib.Path(__file__).parent.parent
+ROUTES_PY = (REPO_ROOT / "api" / "routes.py").read_text(encoding="utf-8")
+
+
+class TestZipMimeMapping(unittest.TestCase):
+    """.zip must resolve to a concrete archive type, not octet-stream."""
+
+    def test_zip_in_mime_map(self):
+        from api.config import MIME_MAP
+
+        self.assertEqual(
+            MIME_MAP.get(".zip"),
+            "application/zip",
+            ".zip must map to application/zip so /api/media can serve archives",
+        )
+
+    def test_zip_not_octet_stream(self):
+        from api.config import MIME_MAP
+
+        self.assertNotEqual(
+            MIME_MAP.get(".zip", "application/octet-stream"),
+            "application/octet-stream",
+            "octet-stream is rejected by the MEDIA: token allow-list",
+        )
+
+
+class TestZipTokenAllowList(unittest.TestCase):
+    """The session MEDIA: token gate must accept archives."""
+
+    def test_archive_types_declared(self):
+        self.assertIn(
+            '_ARCHIVE_TYPES = {"application/zip"}',
+            ROUTES_PY,
+            "_ARCHIVE_TYPES must declare the servable archive types",
+        )
+
+    def test_archive_types_in_session_token_types(self):
+        match = re.search(
+            r"_SESSION_MEDIA_TOKEN_TYPES\s*=\s*\(?\s*(.+?)\)?\n\s*session_media_allowed",
+            ROUTES_PY,
+            re.S,
+        )
+        self.assertIsNotNone(
+            match, "could not locate the _SESSION_MEDIA_TOKEN_TYPES assignment"
+        )
+        self.assertIn(
+            "_ARCHIVE_TYPES",
+            match.group(1),
+            "_SESSION_MEDIA_TOKEN_TYPES must include _ARCHIVE_TYPES",
+        )
+
+
+class TestZipIsDownloadOnly(unittest.TestCase):
+    """Archives must never be offered for inline rendering."""
+
+    def test_archive_not_in_inline_preview_types(self):
+        match = re.search(r"_INLINE_PREVIEW_TYPES\s*=\s*(.+)", ROUTES_PY)
+        self.assertIsNotNone(match, "could not locate _INLINE_PREVIEW_TYPES")
+        self.assertNotIn(
+            "_ARCHIVE_TYPES",
+            match.group(1),
+            "archives must not be inline-previewable; they must download",
+        )
+
+    def test_archive_not_in_inline_image_types(self):
+        match = re.search(r"_INLINE_IMAGE_TYPES\s*=\s*\{(.+?)\}", ROUTES_PY, re.S)
+        self.assertIsNotNone(match, "could not locate _INLINE_IMAGE_TYPES")
+        self.assertNotIn(
+            "zip",
+            match.group(1),
+            "zip must not be treated as an inline image type",
+        )
+
+
+if __name__ == "__main__":
+    unittest.main()