feat(sentiment): search crypto communities on Reddit for a crypto ticker (#1461)

- a crypto pair is searched in r/CryptoCurrency and r/CryptoMarkets, plus r/Bitcoin, r/ethereum or r/solana for those coins, still in one request
- the Sentiment Analyst's prompt names the subreddits actually searched

tests/test_reddit_fallback.py

@@ -311,3 +311,25 @@ def test_an_unavailable_screen_keeps_every_post_and_says_so():
         screened = reddit.fetch_reddit_posts("NVDA", subreddits=("a", "b"), screen=unavailable)
         plain = reddit.fetch_reddit_posts("NVDA", subreddits=("a", "b"))
     assert screened == "<Jev screening unavailable (HTTP 529); posts are unscreened>\n\n" + plain
+
+
+@pytest.mark.unit
+@pytest.mark.parametrize("ticker, expected", [
+    ("NVDA", ("wallstreetbets", "stocks", "investing")),
+    ("BTC-USD", ("Bitcoin", "CryptoCurrency", "CryptoMarkets")),
+    ("ETH-USD", ("ethereum", "CryptoCurrency", "CryptoMarkets")),
+    ("SOL-USD", ("solana", "CryptoCurrency", "CryptoMarkets")),
+    ("DOGE-USD", ("CryptoCurrency", "CryptoMarkets")),
+])
+def test_a_crypto_ticker_is_searched_in_crypto_communities(ticker, expected):
+    assert reddit.subreddits_for(ticker) == expected
+
+
+@pytest.mark.unit
+def test_a_crypto_pair_is_fetched_from_its_communities_in_one_request():
+    with patch.object(reddit, "_fetch_subreddit_rss", return_value=[]) as fetch:
+        out = reddit.fetch_reddit_posts("ETH-USD")
+    fetch.assert_called_once()
+    query, subs = fetch.call_args.args[:2]
+    assert (query, subs) == ("ETH", "ethereum+CryptoCurrency+CryptoMarkets")
+    assert "r/wallstreetbets" not in out

tests/test_structured_agent_prompts.py

@@ -146,3 +146,23 @@ def test_constraint_text_is_unambiguous():
     # No template braces: it is embedded in ChatPromptTemplate strings, where
     # braces would be parsed as input variables.
     assert "{" not in NO_EXTERNAL_TOOLS and "}" not in NO_EXTERNAL_TOOLS
+
+
+@pytest.mark.unit
+def test_the_sentiment_prompt_names_the_subreddits_searched(monkeypatch):
+    from tradingagents.agents.schemas import SentimentBand, SentimentReport
+
+    monkeypatch.setattr(sentiment, "fetch_stocktwits_messages", lambda *a, **k: "st")
+    monkeypatch.setattr(sentiment, "fetch_reddit_posts", lambda *a, **k: "rd")
+    monkeypatch.setattr(sentiment.get_news, "func", lambda *a, **k: "news", raising=False)
+    captured = {}
+    llm = _capturing_llm(captured, SentimentReport(
+        overall_band=SentimentBand.NEUTRAL, overall_score=5.0, confidence="low", narrative="n",
+    ))
+    sentiment.create_sentiment_analyst(llm)({
+        "company_of_interest": "BTC-USD", "trade_date": "2026-01-15",
+        "asset_type": "crypto", "messages": [],
+    })
+    text = _prompt_text(captured["prompt"])
+    assert "r/Bitcoin, r/CryptoCurrency, r/CryptoMarkets" in text
+    assert "wallstreetbets" not in text