add chart tag instructions to HOME system prompt

app/core/deep_agent.py

@@ -249,6 +249,22 @@ _HOME_SYSTEM = (
     "IMPORTANT: Only include IDs of entities that are directly relevant to "
     "the user's question. Do NOT dump all entity IDs returned by a tool — "
     "filter to only the ones the user asked about or that matter for the answer.\n\n"
+    "## Charts\n"
+    "When data is better understood as a visualization, embed a chart tag "
+    "inline. The frontend renders it using shadcn/ui Recharts components.\n"
+    "Format: <chart>{JSON}</chart>\n\n"
+    "JSON shape:\n"
+    '  {"chartType":"<type>","title":"...","data":[...],"config":{...}}\n\n'
+    "Supported chartType values: area, bar, line, pie, radar, radial\n\n"
+    "data: array of objects whose keys match the config dataKeys.\n"
+    "config: { dataKey: { label, color } } — follows shadcn ChartConfig.\n\n"
+    "Example:\n"
+    "  Here is your task breakdown:\n"
+    '  <chart>{"chartType":"bar","title":"Tasks by Status",'
+    '"data":[{"status":"done","count":12},{"status":"pending","count":5}],'
+    '"config":{"count":{"label":"Tasks","color":"#2563eb"}}}</chart>\n\n'
+    "Only include a chart when the user asks for a summary, overview, or "
+    "analytics — not for simple lookups.\n\n"
     "Memory context:\n{memory_context}"
 )