fix(dataflows): trim social sentiment sources to the analysis window

- StockTwits and Reddit were fetched with no date, so a historical run showed
  today's chatter as if it were from the as-of date
- pass the analysis window to both fetchers, filter to it, and emit a clear
  placeholder when nothing qualifies
- centralize the UTC half-open window rule in dataflows/date_window so news,
  StockTwits, and Reddit share one look-ahead-safe filter #1220

tests/test_social_lookahead.py

@@ -0,0 +1,121 @@
+"""Historical social sentiment must not leak current data into a backtest (#1220).
+
+StockTwits and Reddit fetchers pull only recent items, so for a historical run
+they must be trimmed to the analysis window (and yield a clear placeholder when
+nothing qualifies) rather than showing today's chatter as if it were from the
+as-of date. All three sources share dataflows.date_window.in_window.
+"""
+from __future__ import annotations
+
+import json
+from datetime import datetime, timezone
+
+import pytest
+
+from tradingagents.dataflows import reddit, stocktwits
+from tradingagents.dataflows.date_window import in_window
+
+
+class _JsonResp:
+    """Minimal urlopen() context-manager stub returning a JSON body."""
+
+    def __init__(self, payload):
+        self._body = json.dumps(payload).encode()
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *a):
+        return False
+
+    def read(self):
+        return self._body
+
+
+# --- shared window helper ---------------------------------------------------
+
+@pytest.mark.unit
+def test_in_window_bounds_and_exclusive_upper():
+    start = datetime(2026, 5, 1)
+    end = datetime(2026, 5, 9)
+    assert in_window(datetime(2026, 5, 5, tzinfo=timezone.utc), start, end) is True
+    assert in_window(datetime(2026, 5, 9, 23, 59, tzinfo=timezone.utc), start, end) is True
+    # exactly midnight after end -> excluded (no leak)
+    assert in_window(datetime(2026, 5, 10, 0, 0, tzinfo=timezone.utc), start, end) is False
+    # offset-aware converted, not truncated: 05-10T01:00+05:00 == 05-09T20:00Z
+    assert in_window(datetime.fromisoformat("2026-05-10T01:00:00+05:00"), start, end) is True
+
+
+@pytest.mark.unit
+def test_in_window_undated_excluded_in_backtest_kept_live():
+    old = datetime(2026, 5, 9)
+    assert in_window(None, datetime(2026, 5, 1), old) is False       # historical
+    now = datetime.now(timezone.utc)
+    assert in_window(None, now, now) is True                          # live
+
+
+# --- StockTwits -------------------------------------------------------------
+
+def _msg(created_iso, sentiment=None):
+    return {
+        "created_at": created_iso,
+        "user": {"username": "u"},
+        "entities": {"sentiment": {"basic": sentiment}},
+        "body": "text",
+    }
+
+
+@pytest.mark.unit
+def test_stocktwits_historical_window_excludes_recent(monkeypatch):
+    # All messages are "today"; a run as-of a past week must show none of them.
+    recent = [_msg("2026-08-30T12:00:00Z", "Bullish"), _msg("2026-08-29T09:00:00Z")]
+    monkeypatch.setattr(stocktwits, "urlopen", lambda *a, **k: _JsonResp({"messages": recent}))
+    out = stocktwits.fetch_stocktwits_messages("AAPL", start_date="2026-05-01", end_date="2026-05-08")
+    assert "no StockTwits messages" in out
+    assert "2026-05-01..2026-05-08" in out
+    assert "Bullish: 1" not in out  # the recent bullish message did not leak
+
+
+@pytest.mark.unit
+def test_stocktwits_live_window_keeps_in_range(monkeypatch):
+    msgs = [_msg("2026-05-05T12:00:00Z", "Bullish"), _msg("2026-05-07T09:00:00Z", "Bearish")]
+    monkeypatch.setattr(stocktwits, "urlopen", lambda *a, **k: _JsonResp({"messages": msgs}))
+    out = stocktwits.fetch_stocktwits_messages("AAPL", start_date="2026-05-01", end_date="2026-05-08")
+    assert "Total: 2" in out
+
+
+@pytest.mark.unit
+def test_stocktwits_no_window_is_unfiltered(monkeypatch):
+    msgs = [_msg("2026-08-30T12:00:00Z", "Bullish")]
+    monkeypatch.setattr(stocktwits, "urlopen", lambda *a, **k: _JsonResp({"messages": msgs}))
+    out = stocktwits.fetch_stocktwits_messages("AAPL")  # live caller, no dates
+    assert "Total: 1" in out
+
+
+# --- Reddit -----------------------------------------------------------------
+
+def _epoch(date_str):
+    return int(datetime.strptime(date_str, "%Y-%m-%d").replace(tzinfo=timezone.utc).timestamp())
+
+
+@pytest.mark.unit
+def test_reddit_historical_window_excludes_recent(monkeypatch):
+    posts = [{"title": "NOW", "created_utc": _epoch("2026-08-30"), "source": "rss"}]
+    monkeypatch.setattr(reddit, "_fetch_subreddit", lambda *a, **k: posts)
+    out = reddit.fetch_reddit_posts(
+        "AAPL", subreddits=("stocks",), inter_request_delay=0,
+        start_date="2026-05-01", end_date="2026-05-08",
+    )
+    assert "NOW" not in out
+    assert "no posts" in out.lower() or "no reddit posts" in out.lower()
+
+
+@pytest.mark.unit
+def test_reddit_live_window_keeps_in_range(monkeypatch):
+    posts = [{"title": "INRANGE", "created_utc": _epoch("2026-05-05"), "source": "rss"}]
+    monkeypatch.setattr(reddit, "_fetch_subreddit", lambda *a, **k: posts)
+    out = reddit.fetch_reddit_posts(
+        "AAPL", subreddits=("stocks",), inter_request_delay=0,
+        start_date="2026-05-01", end_date="2026-05-08",
+    )
+    assert "INRANGE" in out

tradingagents/agents/analysts/sentiment_analyst.py

@@ -68,8 +68,12 @@ def create_sentiment_analyst(llm):
         # returns a string (no exceptions surface from here), so the LLM
         # always sees something — either real data or a clear placeholder.
         news_block = get_news.func(ticker, start_date, end_date)
-        stocktwits_block = fetch_stocktwits_messages(ticker, limit=30)
-        reddit_block = fetch_reddit_posts(ticker)
+        # Pass the analysis window so a historical run trims social posts to it
+        # instead of leaking today's chatter into a backtest (#1220).
+        stocktwits_block = fetch_stocktwits_messages(
+            ticker, limit=30, start_date=start_date, end_date=end_date
+        )
+        reddit_block = fetch_reddit_posts(ticker, start_date=start_date, end_date=end_date)
 
         system_message = _build_system_message(
             ticker=ticker,

tradingagents/dataflows/date_window.py

@@ -0,0 +1,30 @@
+"""Shared look-ahead-safe date-window filtering for dated content.
+
+News, StockTwits, and Reddit all pull recent items that must be trimmed to the
+analysis window so a historical/backtest run never sees content published after
+its as-of date. Centralizing the rule keeps every source consistent (#1126,
+#1220): every timestamp is normalized to UTC, the upper bound is exclusive at
+midnight after ``end`` (so an item stamped exactly then can't leak), and an
+undated item is kept only when the window reaches the present (a live run), since
+in a backtest we can't prove it isn't future.
+"""
+
+from __future__ import annotations
+
+from datetime import datetime, timedelta, timezone
+
+
+def to_utc(dt: datetime) -> datetime:
+    """Normalize a datetime to UTC-aware; a naive value is assumed to be UTC."""
+    return dt.replace(tzinfo=timezone.utc) if dt.tzinfo is None else dt.astimezone(timezone.utc)
+
+
+def in_window(pub_dt: datetime | None, start_dt: datetime, end_dt: datetime) -> bool:
+    """Whether an item belongs in the half-open window ``[start, end + 1 day)``.
+
+    ``pub_dt`` None means undated: kept only when the window reaches the present.
+    """
+    end = to_utc(end_dt)
+    if pub_dt is not None:
+        return to_utc(start_dt) <= to_utc(pub_dt) < end + timedelta(days=1)
+    return end >= datetime.now(timezone.utc) - timedelta(days=1)

tradingagents/dataflows/reddit.py

@@ -25,15 +25,35 @@ import re
 import time
 import xml.etree.ElementTree as ET
 from collections.abc import Iterable
-from datetime import datetime
+from datetime import datetime, timezone
 from urllib.error import HTTPError
 from urllib.parse import urlencode
 from urllib.request import Request, urlopen
 
+from .date_window import in_window
 from .symbol_utils import crypto_base
 
 logger = logging.getLogger(__name__)
 
+
+def _within_window(posts, start_date, end_date):
+    """Keep only posts published in [start_date, end_date] (look-ahead safe).
+
+    No window (both None) leaves the list untouched for live callers. A post with
+    no ``created_utc`` epoch is dropped in a historical window (#1220).
+    """
+    if not (start_date and end_date):
+        return posts
+    start_dt = datetime.strptime(start_date, "%Y-%m-%d")
+    end_dt = datetime.strptime(end_date, "%Y-%m-%d")
+    kept = []
+    for p in posts:
+        ts = p.get("created_utc")
+        created = datetime.fromtimestamp(ts, tz=timezone.utc) if ts else None
+        if in_window(created, start_dt, end_dt):
+            kept.append(p)
+    return kept
+
 _API = "https://www.reddit.com/r/{sub}/search.json?{qs}"
 _RSS = "https://www.reddit.com/r/{sub}/search.rss?{qs}"
 # A descriptive, identified User-Agent (per Reddit's API etiquette). Reddit
@@ -194,6 +214,8 @@ def fetch_reddit_posts(
     limit_per_sub: int = 5,
     timeout: float = 10.0,
     inter_request_delay: float = 1.0,
+    start_date: str | None = None,
+    end_date: str | None = None,
 ) -> str:
     """Fetch recent Reddit posts mentioning ``ticker`` across finance
     subreddits and return them as a formatted plaintext block.
@@ -201,6 +223,10 @@ def fetch_reddit_posts(
     ``inter_request_delay`` paces the (now RSS-only) per-subreddit requests to
     stay under Reddit's public per-IP rate limit; combined with the RSS-first
     path it makes 429s rare even when several analyses run back-to-back.
+
+    When ``start_date``/``end_date`` (yyyy-mm-dd) are given, posts are trimmed to
+    that window so a historical run does not leak current discussion into a
+    backtest (#1220).
     """
     # Crypto reaches us as a Yahoo pair (BTC-USD); search Reddit for the base
     # ("BTC") so the query actually matches discussion instead of near-nothing.
@@ -210,7 +236,8 @@ def fetch_reddit_posts(
     for i, sub in enumerate(subreddits):
         if i > 0:
             time.sleep(inter_request_delay)
-        posts = _fetch_subreddit(ticker, sub, limit_per_sub, timeout)
+        posts = _within_window(_fetch_subreddit(ticker, sub, limit_per_sub, timeout),
+                               start_date, end_date)
         total_posts += len(posts)
         if not posts:
             blocks.append(f"r/{sub}: <no posts found mentioning {ticker.upper()} in the past 7 days>")

tradingagents/dataflows/stocktwits.py

@@ -14,11 +14,14 @@ network call succeeded.
 
 from __future__ import annotations
 
+import contextlib
 import http.client
 import json
 import logging
+from datetime import datetime
 from urllib.request import Request, urlopen
 
+from .date_window import in_window
 from .symbol_utils import crypto_base
 
 logger = logging.getLogger(__name__)
@@ -27,6 +30,29 @@ _API = "https://api.stocktwits.com/api/2/streams/symbol/{ticker}.json"
 _UA = "tradingagents/0.2 (+https://github.com/TauricResearch/TradingAgents)"
 
 
+def _within_window(messages, start_date, end_date):
+    """Keep only messages published in [start_date, end_date] (look-ahead safe).
+
+    No window (both None) leaves the list untouched for live callers. A message
+    whose ``created_at`` (ISO 8601) is unparseable is dropped in a historical
+    window, since we can't prove it isn't from after the as-of date (#1220).
+    """
+    if not (start_date and end_date):
+        return messages
+    start_dt = datetime.strptime(start_date, "%Y-%m-%d")
+    end_dt = datetime.strptime(end_date, "%Y-%m-%d")
+    kept = []
+    for m in messages:
+        created = None
+        raw = m.get("created_at")
+        if raw:
+            with contextlib.suppress(ValueError, TypeError):
+                created = datetime.fromisoformat(str(raw).replace("Z", "+00:00"))
+        if in_window(created, start_dt, end_dt):
+            kept.append(m)
+    return kept
+
+
 def _stocktwits_symbol(ticker: str) -> str:
     """Map a crypto pair to StockTwits' ``<BASE>.X`` convention.
 
@@ -38,10 +64,21 @@ def _stocktwits_symbol(ticker: str) -> str:
     return f"{base}.X" if base else ticker.strip().upper()
 
 
-def fetch_stocktwits_messages(ticker: str, limit: int = 30, timeout: float = 10.0) -> str:
+def fetch_stocktwits_messages(
+    ticker: str,
+    limit: int = 30,
+    timeout: float = 10.0,
+    start_date: str | None = None,
+    end_date: str | None = None,
+) -> str:
     """Fetch recent StockTwits messages for ``ticker`` and return them as a
     formatted plaintext block ready for prompt injection.
 
+    When ``start_date``/``end_date`` (yyyy-mm-dd) are given, messages are trimmed
+    to that window. The StockTwits public stream only serves recent messages, so
+    for a historical run they all fall after the window and a clear placeholder
+    is returned rather than leaking today's chatter into a backtest (#1220).
+
     Returns a placeholder string when the endpoint is unreachable, the
     symbol has no messages, or the response shape is unexpected — the
     caller never has to special-case None or exceptions.
@@ -58,7 +95,13 @@ def fetch_stocktwits_messages(ticker: str, limit: int = 30, timeout: float = 10.
         return f"<stocktwits unavailable: {type(exc).__name__}>"
 
     messages = data.get("messages", []) if isinstance(data, dict) else []
+    messages = _within_window(messages, start_date, end_date)
     if not messages:
+        if start_date and end_date:
+            return (
+                f"<no StockTwits messages for ${ticker.upper()} within "
+                f"{start_date}..{end_date} (public stream serves only recent messages)>"
+            )
         return f"<no StockTwits messages found for ${ticker.upper()}>"
 
     lines = []

tradingagents/dataflows/yfinance_news.py

@@ -1,26 +1,17 @@
 """yfinance-based news data fetching functions."""
 
 import contextlib
-from datetime import datetime, timedelta, timezone
+from datetime import datetime, timezone
 
 import yfinance as yf
 from dateutil.relativedelta import relativedelta
 
 from .config import get_config
+from .date_window import in_window
 from .stockstats_utils import yf_retry
 from .symbol_utils import normalize_symbol
 
 
-def _as_utc(dt: datetime) -> datetime:
-    """Normalize a datetime to UTC-aware; a naive value is assumed to be UTC.
-
-    Window bounds arrive naive (parsed from ``yyyy-mm-dd``) while article
-    timestamps may be offset-aware, so every operand is normalized before
-    comparison. Without this the filter depends on the host timezone (#1126).
-    """
-    return dt.replace(tzinfo=timezone.utc) if dt.tzinfo is None else dt.astimezone(timezone.utc)
-
-
 def _extract_article_data(article: dict) -> dict:
     """Extract article data from yfinance news format (handles nested 'content' structure)."""
     # Handle nested content structure
@@ -70,18 +61,8 @@ def _extract_article_data(article: dict) -> dict:
 
 
 def _in_news_window(pub_date, start_dt, end_dt) -> bool:
-    """Whether an article belongs in the half-open window ``[start, end + 1 day)``.
-
-    Every operand is normalized to UTC, and the upper bound is exclusive so an
-    article stamped exactly at midnight after ``end_dt`` cannot leak into a
-    historical run (#1126). An undated article is kept only when the window
-    reaches the present (live run) — in a historical/backtest window it's
-    excluded, since we can't prove it isn't future news (#992/#1007).
-    """
-    end = _as_utc(end_dt)
-    if pub_date is not None:
-        return _as_utc(start_dt) <= _as_utc(pub_date) < end + timedelta(days=1)
-    return end >= datetime.now(timezone.utc) - timedelta(days=1)
+    """Look-ahead-safe article-window check; see dataflows.date_window.in_window."""
+    return in_window(pub_date, start_dt, end_dt)
 
 
 def get_news_yfinance(