From 0930e08496c1d94977bae3acab73c58bbd0aa3c9 Mon Sep 17 00:00:00 2001
From: Roland Tannous <rolandtannous@gravityq.ai>
Date: Wed, 3 Jun 2026 12:01:54 +0400
Subject: [PATCH] RAG preview: serve preview files frame-safe for the native
 PDF viewer

---
 studio/backend/main.py       | 14 +++++++++++++-
 studio/backend/routes/rag.py | 11 +++++++++++
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/studio/backend/main.py b/studio/backend/main.py
index 67cc7539a3..2f12557f82 100644
--- a/studio/backend/main.py
+++ b/studio/backend/main.py
@@ -440,6 +440,18 @@ _CSP_SCRIPT_NONCE_HEADER = "x-internal-script-nonce"
 _ARTIFACT_PREVIEW_FRAME_PATH = "/api/inference/artifact-preview-frame"
 
 
+def _is_frameable_path(path: str) -> bool:
+    """Paths allowed to be embedded in a same-origin / Tauri iframe. These
+    responses set their own CSP frame-ancestors; X-Frame-Options: DENY would
+    override that, so it is skipped for them."""
+    if path == _ARTIFACT_PREVIEW_FRAME_PATH:
+        return True
+    # RAG PDF preview is shown in the browser's native viewer inside an iframe.
+    return path.startswith("/api/rag/documents/") and path.endswith(
+        ("/file", "/file-signed")
+    )
+
+
 # /content is Colab's working directory — more reliable than env vars which
 # aren't always set depending on Colab runtime version.
 import importlib.util as _importlib_util
@@ -510,7 +522,7 @@ class SecurityHeadersMiddleware(BaseHTTPMiddleware):
         response.headers.setdefault("Content-Security-Policy", _build_csp(nonce))
         # Omit X-Frame-Options in Colab — CSP frame-ancestors handles it, and
         # DENY would block serve_kernel_port_as_iframe regardless of CSP.
-        if not _IS_COLAB and request.url.path != _ARTIFACT_PREVIEW_FRAME_PATH:
+        if not _IS_COLAB and not _is_frameable_path(request.url.path):
             response.headers.setdefault("X-Frame-Options", "DENY")
         response.headers.setdefault("X-Content-Type-Options", "nosniff")
         response.headers.setdefault("Referrer-Policy", "no-referrer")
diff --git a/studio/backend/routes/rag.py b/studio/backend/routes/rag.py
index ebbc327346..96b95efe94 100644
--- a/studio/backend/routes/rag.py
+++ b/studio/backend/routes/rag.py
@@ -1181,6 +1181,12 @@ def _iter_file_range(path: Path, start: int, end: int):
             yield chunk
 
 
+# Origins allowed to embed the preview file in an iframe: the web app (same
+# origin) and the desktop Tauri webview. Mirrors routes/inference.py's
+# artifact-preview frame ancestors.
+_PREVIEW_FRAME_ANCESTORS = "'self' tauri://localhost http://tauri.localhost"
+
+
 def _serve_document_file_row(
     doc_row: Any,
     document_id: str,
@@ -1194,6 +1200,11 @@ def _serve_document_file_row(
         "X-Content-Type-Options": "nosniff",
         "Cache-Control": "private, max-age=0, must-revalidate",
         "Accept-Ranges": "bytes",
+        # The PDF preview embeds this file in a same-origin / Tauri iframe shown
+        # in the browser's native viewer. The global SecurityHeadersMiddleware
+        # sets frame-ancestors 'none'; override it here (and this path is exempt
+        # from X-Frame-Options: DENY in main.py) so the iframe can load.
+        "Content-Security-Policy": f"frame-ancestors {_PREVIEW_FRAME_ANCESTORS}",
     }
     size = resolved.stat().st_size