Update app.py

app.py

@@ -1,5 +1,6 @@
 # --- minimal dependencies ---
 import os, re, json, requests
+import chess
 import gradio as gr
 import pandas as pd
 from huggingface_hub import InferenceClient  # add to requirements.txt
@@ -7,6 +8,7 @@ from huggingface_hub import InferenceClient  # add to requirements.txt
 DEFAULT_API_URL = "https://agents-course-unit4-scoring.hf.space"
 YOUTUBE_RE = re.compile(r"https?://(?:www\.)?youtube\.com/watch\?v=[\w-]+")
 REV_INSTR_RX = re.compile(r'opposite of the word ["“]?([A-Za-z]+)["”]?', re.I)
+FEN_RX = re.compile(r"\bfen\b[:\s]*([rnbqkRNBQK1-8/]+\s+[bw]\s+[KQkq\-]+(?:\s+[a-h36\-]+){2}\s*\d*\s*\d*)", re.I)
 
 NUM_WORDS = {
     "zero":"0","one":"1","two":"2","three":"3","four":"4","five":"5",
@@ -230,6 +232,37 @@ class BasicAgent:
     
         return None
 
+    def _extract_fen(self, text: str) -> str | None:
+        if not text: 
+            return None
+        m = FEN_RX.search(text)
+        if m:
+            return " ".join(m.group(1).split())  # normalize whitespace
+        # fallback: sometimes file is just the fen line
+        t = text.strip()
+        if "/" in t and " w " in t or " b " in t:
+            return " ".join(t.split())
+        return None
+
+    def _solve_chess_mate_in_one(self, fen: str) -> str | None:
+        try:
+            board = chess.Board(fen)
+        except Exception:
+            return None
+    # It’s black’s turn per question; trust FEN side-to-move. If mismatch, flip.
+    # (Optional safety)
+    # if "black" in self._last_question.lower() and board.turn == chess.WHITE:
+    #     return None
+
+        for mv in board.legal_moves:
+            board.push(mv)
+            is_mate = board.is_checkmate()
+            san = board.san(mv)  # SAN before popping while board still in that state
+            board.pop()
+            if is_mate:
+                return san  # e.g., "Qg2#"
+        return None
+
     # change the template call to pass task_id as second arg
     def __call__(self, question: str, task_id: str | None = None) -> str:
         ql = question.lower()
@@ -239,6 +272,16 @@ class BasicAgent:
         if rev_ans is not None:
             return rev_ans
 
+
+        # CHESS fast-path
+        if ("chess" in ql or "algebraic notation" in ql or "diagram" in ql or "board" in ql) and task_id:
+            file_text = self._fetch_file_text(task_id)
+            fen = self._extract_fen(file_text or "")
+            if fen:
+                san = self._solve_chess_mate_in_one(fen)
+                if san:
+                    return san
+
         # 0) YouTube special-case: count distinct bird species from description
         m = YOUTUBE_RE.search(question)
         if m: