fix(dataflows): honour Reddit Retry-After: 0 and jitter 429 backoff

- a valid Retry-After: 0 means retry at once but was treated as absent
  (`or 5.0`) and waited 5s; honour it exactly now
- jitter our own headerless fallback and the inter-subreddit pacing so several
  analyses sharing an IP don't retry in lockstep and re-collide on the limit;
  keep the single-retry ceiling (more retries can't fix an exhausted IP budget) #1193

tests/test_reddit_fallback.py

@@ -147,6 +147,26 @@ class TestRss429Backoff:
             reddit._fetch_subreddit_rss("NVDA", "stocks", 5, 5.0)
         slept.assert_called_once_with(12.0)
 
+    def test_retry_after_zero_is_honoured_not_treated_as_absent(self):
+        # A valid "Retry-After: 0" means retry at once; it must not fall through
+        # to the fallback wait (the earlier `or 5.0` bug turned 0 into 5s).
+        err = HTTPError("url", 429, "Too Many Requests", {"Retry-After": "0"}, None)
+        with patch.object(reddit, "urlopen", side_effect=[err, _atom_resp()]), \
+             patch.object(reddit.time, "sleep") as slept:
+            reddit._fetch_subreddit_rss("NVDA", "stocks", 5, 5.0)
+        slept.assert_called_once_with(0.0)
+
+    def test_headerless_429_fallback_is_jittered(self):
+        # No Retry-After -> our own ~5s fallback, jittered so concurrent runs
+        # don't retry in lockstep (kept within a tight band).
+        err = HTTPError("url", 429, "Too Many Requests", {}, None)
+        with patch.object(reddit, "urlopen", side_effect=[err, _atom_resp()]), \
+             patch.object(reddit.time, "sleep") as slept:
+            reddit._fetch_subreddit_rss("NVDA", "stocks", 5, 5.0)
+        slept.assert_called_once()
+        (wait,), _ = slept.call_args
+        assert 4.0 <= wait <= 6.0  # 5s +/-20% jitter
+
 
 @pytest.mark.unit
 class TestChunkedTransferErrorsHandled:

tradingagents/dataflows/reddit.py

@@ -21,6 +21,7 @@ import html
 import http.client
 import json
 import logging
+import random
 import re
 import time
 import xml.etree.ElementTree as ET
@@ -101,11 +102,26 @@ def _strip_html(content: str) -> str:
     return " ".join(html.unescape(text).split())
 
 
+# Headerless-429 backoff when Reddit gives no Retry-After. Jittered so several
+# analyses sharing an IP don't retry in lockstep and re-collide on the limit.
+_RETRY_FALLBACK_SECONDS = 5.0
+
+
+def _jitter(seconds: float, frac: float = 0.2) -> float:
+    """Return ``seconds`` with +/-``frac`` random jitter, to desynchronize
+    concurrent runs pacing against the same per-IP limit."""
+    return seconds * (1.0 + random.uniform(-frac, frac))
+
+
 def _retry_after_seconds(exc: HTTPError) -> float | None:
-    """Seconds to wait from a 429's ``Retry-After`` header, capped at 30s."""
+    """Seconds to wait from a 429's ``Retry-After`` header, capped at 30s.
+
+    Returns ``None`` only when the header is absent or unparseable; a valid
+    ``Retry-After: 0`` returns ``0.0`` (retry at once), not ``None``.
+    """
     try:
         val = exc.headers.get("Retry-After") if getattr(exc, "headers", None) else None
-        return min(float(val), 30.0) if val else None
+        return min(float(val), 30.0) if val is not None else None
     except (ValueError, TypeError, AttributeError):
         return None
 
@@ -131,7 +147,10 @@ def _fetch_subreddit_rss(
             root = ET.fromstring(resp.read())
     except HTTPError as exc:
         if exc.code == 429 and _retry:
-            wait = _retry_after_seconds(exc) or 5.0
+            # Honour a server-supplied Retry-After exactly (including 0); jitter
+            # only our own fallback so concurrent runs don't retry in lockstep.
+            retry_after = _retry_after_seconds(exc)
+            wait = retry_after if retry_after is not None else _jitter(_RETRY_FALLBACK_SECONDS)
             logger.warning(
                 "Reddit RSS 429 for r/%s · %s — backing off %.1fs then retrying once",
                 sub, ticker, wait,
@@ -234,8 +253,8 @@ def fetch_reddit_posts(
     blocks = []
     total_posts = 0
     for i, sub in enumerate(subreddits):
-        if i > 0:
-            time.sleep(inter_request_delay)
+        if i > 0 and inter_request_delay:
+            time.sleep(_jitter(inter_request_delay))
         posts = _within_window(_fetch_subreddit(ticker, sub, limit_per_sub, timeout),
                                start_date, end_date)
         total_posts += len(posts)