fix(preview): harden sandbox and transformation

synapse/tools.py

@@ -393,7 +393,15 @@ def _critique_shared(markup: str) -> list[str]:
     issues: list[str] = []
     lower = markup.lower()
 
-    if re.search(r"""(?i)(?:src|href)\s*=\s*['"]https?://""", markup):
+    external_attr = re.search(
+        r"""(?i)\b(?:src|srcset|href|xlink:href|poster|action|formaction|data)\b\s*=\s*(?:['"]\s*)?https?://""",
+        markup,
+    )
+    external_css = re.search(
+        r"""(?i)(?:url\s*\(\s*['"]?\s*https?://|@import\s+(?:url\s*\(\s*)?['"]?\s*https?://)""",
+        markup,
+    )
+    if external_attr or external_css:
         issues.append(
             "Remove external http(s) URLs — the sandboxed preview blocks them. "
             "Inline CSS/JS; use data: URIs for images/fonts."
@@ -1014,14 +1022,15 @@ STANDING_TOOLS = frozenset({"render_preview"})
 # User-message cues that justify running the (slow, non-stream) tool loop with
 # render_preview. Kept narrow so ordinary chat isn't blocked behind a tool turn.
 _RENDER_HINTS = (
-    "visual", "visualize", "visualization", "chart", "graph", "diagram",
-    "canvas", "plot", "interactive", "animation", "render_preview",
+    "visual", "visuals", "visualize", "visualization", "chart", "charts",
+    "graph", "graphs", "diagram", "diagrams", "canvas", "plot", "plots",
+    "interactive", "animation", "animations", "render_preview",
     "render preview", "svg", "draw me", "live preview",
     "demonstrate", "demo", "html demo", "html snippet", "html file",
     # Ways of asking for something that reacts to the pointer. "interactive"
     # alone missed "mouse-over sensitive", and with it the whole feature.
     "hover", "mouse", "drag", "click on", "real-time", "realtime",
-    "simulation", "simulate", "particle", "animate",
+    "simulation", "simulations", "simulate", "particle", "particles", "animate",
     # Every language the render window can display. Naming one is asking for a
     # preview, and this way a language added to PREVIEW_LANGS starts hinting
     # for itself instead of being unreachable until someone edits this tuple -
@@ -1031,8 +1040,12 @@ _RENDER_HINTS = (
 
 def wants_render_preview(message: str) -> bool:
     """True when this turn should advertise render_preview / enter the tool loop."""
+    import re
     lower = (message or "").lower()
-    return any(h in lower for h in _RENDER_HINTS)
+    return any(
+        re.search(rf"(?<![A-Za-z0-9_]){re.escape(hint)}(?![A-Za-z0-9_])", lower)
+        for hint in _RENDER_HINTS
+    )
 
 
 def is_action(name: str) -> bool: