fix: retry transient Tencent quote failures

src/grid_trading/market/tencent.py

@@ -50,10 +50,12 @@ class TencentQuoteProvider:
         *,
         endpoint: str = TENCENT_ENDPOINT,
         timeout: float = 5.0,
+        retries: int = 1,
         fetcher: Callable[[str, float], bytes] | None = None,
     ):
         self.endpoint = endpoint
         self.timeout = timeout
+        self.retries = retries
         self._fetcher = fetcher or _default_fetcher
 
     def fetch_quotes(self, instruments: Iterable[Instrument]) -> dict[str, QuoteSnapshot]:
@@ -62,12 +64,18 @@ class TencentQuoteProvider:
             return {}
         query = ",".join(symbols)
         url = f"{self.endpoint}{query}"
-        try:
-            raw = self._fetcher(url, self.timeout)
-        except (OSError, HTTPError, URLError) as exc:
-            raise QuoteFetchError(f"Tencent quote request failed: {exc}") from exc
+        raw = self._fetch_with_retry(url)
         return {quote.code: quote for quote in parse_tencent_response(raw)}
 
+    def _fetch_with_retry(self, url: str) -> bytes:
+        last_error: Exception | None = None
+        for _ in range(self.retries + 1):
+            try:
+                return self._fetcher(url, self.timeout)
+            except (OSError, HTTPError, URLError) as exc:
+                last_error = exc
+        raise QuoteFetchError(f"Tencent quote request failed: {last_error}") from last_error
+
 
 def _default_fetcher(url: str, timeout: float) -> bytes:
     with urlopen(url, timeout=timeout) as response: