Throttle OKX amp-stats candle pagination and retry on 429.

Add page pauses, exponential backoff, and cooldown before swap fallback to avoid rate limits.

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/test_amp_stats_lib.py

@@ -14,6 +14,8 @@ from lib.hub.amp_stats_lib import (
     window_bounds_for_settlement,
 )
 
+import httpx
+
 TZ = ZoneInfo("Asia/Shanghai")
 
 
@@ -198,11 +200,17 @@ class AmpStatsLibTests(unittest.TestCase):
         calls: list[str] = []
 
         class FakeResp:
-            def __init__(self, data):
+            def __init__(self, data, url="https://x", status_code=200):
                 self._data = data
+                self.status_code = status_code
+                self.url = url
+                self.request = httpx.Request("GET", url)
 
             def raise_for_status(self):
-                return None
+                if self.status_code >= 400:
+                    raise httpx.HTTPStatusError(
+                        "err", request=self.request, response=self
+                    )
 
             def json(self):
                 return {"code": "0", "data": self._data}
@@ -214,14 +222,14 @@ class AmpStatsLibTests(unittest.TestCase):
                 # recent: only 2 pages then empty; history continues
                 if "history" not in url:
                     if after is None:
-                        return FakeResp([["2000", "1", "2", "0.5", "1.5"], ["1900", "1", "2", "0.5", "1.5"]])
+                        return FakeResp([["2000", "1", "2", "0.5", "1.5"], ["1900", "1", "2", "0.5", "1.5"]], url=url)
                     if after == "1900":
-                        return FakeResp([])  # recent exhausted
-                    return FakeResp([])
+                        return FakeResp([], url=url)  # recent exhausted
+                    return FakeResp([], url=url)
                 # history
                 if after == "1900":
-                    return FakeResp([["1800", "1", "2", "0.5", "1.5"], ["1000", "1", "2", "0.5", "1.5"]])
-                return FakeResp([])
+                    return FakeResp([["1800", "1", "2", "0.5", "1.5"], ["1000", "1", "2", "0.5", "1.5"]], url=url)
+                return FakeResp([], url=url)
 
             def close(self):
                 return None
@@ -234,11 +242,57 @@ class AmpStatsLibTests(unittest.TestCase):
             until_ms=3000,
             client=FakeClient(),
             max_pages=10,
+            page_pause_sec=0,
+            history_page_pause_sec=0,
         )
         self.assertTrue(any("history-index-candles" in u for u in calls))
         self.assertGreaterEqual(len(bars), 3)
         self.assertEqual(bars[0]["ts"], 1000)
 
+    def test_fetch_retries_on_429(self):
+        from lib.hub.amp_stats_lib import fetch_okx_candles
+        import httpx as _httpx
+
+        hits = {"n": 0}
+
+        class FakeResp:
+            def __init__(self, status_code, data=None):
+                self.status_code = status_code
+                self.url = "https://www.okx.com/api/v5/market/history-candles"
+                self.request = _httpx.Request("GET", self.url)
+                self._data = data or []
+
+            def raise_for_status(self):
+                if self.status_code >= 400:
+                    raise _httpx.HTTPStatusError("429", request=self.request, response=self)
+
+            def json(self):
+                return {"code": "0", "data": self._data}
+
+        class FakeClient:
+            def get(self, url, params=None):
+                hits["n"] += 1
+                if hits["n"] < 3:
+                    return FakeResp(429)
+                return FakeResp(200, [["1000", "1", "2", "0.5", "1.5"]])
+
+            def close(self):
+                return None
+
+        bars = fetch_okx_candles(
+            url="https://www.okx.com/api/v5/market/candles",
+            history_url=None,
+            inst_id="ETH-USDT-SWAP",
+            since_ms=1000,
+            until_ms=2000,
+            client=FakeClient(),
+            max_pages=3,
+            page_pause_sec=0,
+            history_page_pause_sec=0,
+        )
+        self.assertGreaterEqual(hits["n"], 3)
+        self.assertEqual(len(bars), 1)
+
     def test_compute_with_mock_fetch(self):
         now = datetime(2026, 7, 22, 18, 0, tzinfo=TZ)