feat: chatbot

backend/services/database.py

@@ -135,6 +135,14 @@ def init_db():
             price_at_signal REAL
         )""",
         "ALTER TABLE cycle_runs ADD COLUMN wavelet_signals_count INTEGER DEFAULT 0",
+        # AI Chat widget — persisted conversation turns, one growing thread per session_id
+        """CREATE TABLE IF NOT EXISTS ai_chat_messages (
+            id INTEGER PRIMARY KEY AUTOINCREMENT,
+            session_id TEXT NOT NULL,
+            role TEXT NOT NULL,
+            content TEXT NOT NULL,
+            created_at TEXT DEFAULT (datetime('now'))
+        )""",
     ]:
         try:
             c.execute(_sql)
@@ -146,6 +154,11 @@ def init_db():
     except Exception:
         pass
 
+    try:
+        c.execute("CREATE INDEX IF NOT EXISTS idx_chat_session_date ON ai_chat_messages(session_id, created_at)")
+    except Exception:
+        pass
+
     # Specialist Reports — surprise index + text sentiment columns
     try:
         c.execute("ALTER TABLE specialist_reports ADD COLUMN consensus_estimate REAL")
@@ -3213,6 +3226,35 @@ def get_wavelet_signals_history(ticker: str, days: int = 30) -> List[Dict]:
     return [dict(r) for r in rows]
 
 
+# ── AI Chat widget — persisted conversation ────────────────────────────────────
+
+def save_chat_message(session_id: str, role: str, content: str) -> None:
+    conn = get_conn()
+    conn.execute(
+        "INSERT INTO ai_chat_messages (session_id, role, content) VALUES (?, ?, ?)",
+        (session_id, role, content),
+    )
+    conn.commit()
+    conn.close()
+
+
+def get_chat_messages(session_id: str, limit: int = 100) -> List[Dict]:
+    conn = get_conn()
+    rows = conn.execute(
+        "SELECT role, content, created_at FROM ai_chat_messages WHERE session_id=? ORDER BY id ASC LIMIT ?",
+        (session_id, limit),
+    ).fetchall()
+    conn.close()
+    return [dict(r) for r in rows]
+
+
+def clear_chat_session(session_id: str) -> None:
+    conn = get_conn()
+    conn.execute("DELETE FROM ai_chat_messages WHERE session_id=?", (session_id,))
+    conn.commit()
+    conn.close()
+
+
 # ── System Logs ───────────────────────────────────────────────────────────────
 
 def log_system_event(