From 78a93ee7713156a196602aacce0f3b4a0b7fc301 Mon Sep 17 00:00:00 2001
From: enne2 <me@enne2.net>
Date: Tue, 8 Sep 2026 12:12:38 +0200
Subject: [PATCH] =?UTF-8?q?fix(gateway):=20troncamento=20documenti=20reran?=
 =?UTF-8?q?k=20(RERANK=5FMAX=5FDOC=5FCHARS=3D800)=20=E2=80=94=20evita=2050?=
 =?UTF-8?q?0=20batch-size=20e=20costi=20oltre=20il=20ctx?=
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---
 gateway/config.py            |  1 +
 gateway/rerank.py            |  4 ++++
 gateway/tests/test_rerank.py | 14 ++++++++++++++
 3 files changed, 19 insertions(+)

diff --git a/gateway/config.py b/gateway/config.py
index 00eab85..d7f2d41 100644
--- a/gateway/config.py
+++ b/gateway/config.py
@@ -39,6 +39,7 @@ SPARSE_VECTOR_NAME = "bm25"
 RERANK_ENABLED = os.environ.get("RERANK_ENABLED", "false").lower() == "true"
 RERANK_MODEL = os.environ.get("RERANK_MODEL", "bge-reranker-v2-m3")
 RERANK_CANDIDATES = int(os.environ.get("RERANK_CANDIDATES", "16"))
+RERANK_MAX_DOC_CHARS = int(os.environ.get("RERANK_MAX_DOC_CHARS", "800"))
 RERANK_TIMEOUT_MS = int(os.environ.get("RERANK_TIMEOUT_MS", "10000"))
 RERANK_RETRY_COOLDOWN_S = int(os.environ.get("RERANK_RETRY_COOLDOWN_S", "60"))
 RERANK_CHAIN = os.environ.get("RERANK_CHAIN", "")
diff --git a/gateway/rerank.py b/gateway/rerank.py
index a306f66..c40e6af 100644
--- a/gateway/rerank.py
+++ b/gateway/rerank.py
@@ -21,6 +21,7 @@ import metrics
 from config import (
     RERANK_CHAIN,
     RERANK_ENABLED,
+    RERANK_MAX_DOC_CHARS,
     RERANK_MODEL,
     RERANK_RETRY_COOLDOWN_S,
     RERANK_TIMEOUT_MS,
@@ -121,6 +122,9 @@ async def rerank(query: str, docs: list[str]) -> Optional[tuple[list[float], str
     chain = _get_chain()
     if not chain or not docs:
         return None
+    # Troncamento dei documenti: limita il costo di inferenza (i cross-encoder
+    # scala con la lunghezza della coppia query+doc) e evita input oltre il ctx.
+    docs = [d[:RERANK_MAX_DOC_CHARS] for d in docs]
     live, all_down = live_nodes()
     if not live:
         # tutti in cooldown: ritenta comunque il primo (meglio di un fallimento immediato)
diff --git a/gateway/tests/test_rerank.py b/gateway/tests/test_rerank.py
index 2048169..49922ef 100644
--- a/gateway/tests/test_rerank.py
+++ b/gateway/tests/test_rerank.py
@@ -145,6 +145,20 @@ def test_normalize_score():
     assert rerank.normalize_score(-10.0) < 0.01
 
 
+def test_troncamento_documenti(monkeypatch):
+    _use_chain(monkeypatch)
+    seen: dict = {}
+
+    def handler(request):
+        seen["docs"] = json.loads(request.content)["documents"]
+        return httpx.Response(200, json={"results": [{"index": 0, "relevance_score": 1.0}]})
+
+    _mock_client(handler)
+    asyncio.run(rerank.rerank("q", ["x" * 5000, "corto"]))
+    assert len(seen["docs"][0]) == 800  # default RERANK_MAX_DOC_CHARS
+    assert seen["docs"][1] == "corto"
+
+
 # ---------------------------------------------------------------------------
 # integrazione endpoint search
 # ---------------------------------------------------------------------------