Remove reranker cache

CHANGELOG.md

@@ -1,6 +1,8 @@
 # Changelog
 ## [Unreleased]
 
+- **Reranker Factory**: Removed unreliable `id(config)`-based caching from `get_reranker()`; factory now always instantiates fresh
+
 ## [0.26.7] - 2026-01-20
 
 ### Added
@@ -17,6 +19,8 @@
 
 ### Changed
 
+- **MCP Error Handling**: MCP tools now let exceptions propagate naturally; FastMCP converts them to proper MCP error responses
+- **Chunk Contextualization**: Consolidated duplicate `contextualize` logic into `Chunk.contextualize_content()` method
 - **Type Checker**: Replaced pyright with [ty](https://github.com/astral-sh/ty), Astral's extremely fast Python type checker
   - Added explicit `Agent[Deps, Output]` type annotations to all pydantic-ai agents for better type inference
   - Removed ~24 unnecessary `# type: ignore` comments that ty correctly infers

haiku_rag_slim/haiku/rag/reranking/__init__.py

@@ -3,8 +3,6 @@ import os
 from haiku.rag.config import AppConfig, Config
 from haiku.rag.reranking.base import RerankerBase
 
-_reranker_cache: dict[int, RerankerBase | None] = {}
-
 
 def get_reranker(config: AppConfig = Config) -> RerankerBase | None:
     """
@@ -17,50 +15,41 @@ def get_reranker(config: AppConfig = Config) -> RerankerBase | None:
     Returns:
         A reranker instance if configured, None otherwise.
     """
-    # Use config id as cache key to support multiple configs
-    config_id = id(config)
-    if config_id in _reranker_cache:
-        return _reranker_cache[config_id]
-
-    reranker: RerankerBase | None = None
-
     if config.reranking.model and config.reranking.model.provider == "mxbai":
         try:
             from haiku.rag.reranking.mxbai import MxBAIReranker
 
             os.environ["TOKENIZERS_PARALLELISM"] = "true"
-            reranker = MxBAIReranker()
+            return MxBAIReranker()
         except ImportError:  # pragma: no cover
-            reranker = None
+            return None
 
-    elif config.reranking.model and config.reranking.model.provider == "cohere":
+    if config.reranking.model and config.reranking.model.provider == "cohere":
         try:
             from haiku.rag.reranking.cohere import CohereReranker
 
-            reranker = CohereReranker()
+            return CohereReranker()
         except ImportError:  # pragma: no cover
-            reranker = None
+            return None
 
-    elif config.reranking.model and config.reranking.model.provider == "vllm":
+    if config.reranking.model and config.reranking.model.provider == "vllm":
         try:
             from haiku.rag.reranking.vllm import VLLMReranker
 
             base_url = config.reranking.model.base_url
             if not base_url:
                 raise ValueError("vLLM reranker requires base_url in reranking.model")
-            reranker = VLLMReranker(config.reranking.model.name, base_url)
+            return VLLMReranker(config.reranking.model.name, base_url)
         except ImportError:  # pragma: no cover
-            reranker = None
+            return None
 
-    elif config.reranking.model and config.reranking.model.provider == "zeroentropy":
+    if config.reranking.model and config.reranking.model.provider == "zeroentropy":
         try:
             from haiku.rag.reranking.zeroentropy import ZeroEntropyReranker
 
-            # Use configured model or default to zerank-1
             model = config.reranking.model.name or "zerank-1"
-            reranker = ZeroEntropyReranker(model)
+            return ZeroEntropyReranker(model)
         except ImportError:  # pragma: no cover
-            reranker = None
+            return None
 
-    _reranker_cache[config_id] = reranker
-    return reranker
+    return None

tests/test_reranker.py

@@ -3,7 +3,7 @@ from pathlib import Path
 import pytest
 
 from haiku.rag.config.models import AppConfig, ModelConfig, RerankingConfig
-from haiku.rag.reranking import _reranker_cache, get_reranker
+from haiku.rag.reranking import get_reranker
 from haiku.rag.reranking.base import RerankerBase
 from haiku.rag.store.models.chunk import Chunk
 
@@ -13,14 +13,6 @@ def vcr_cassette_dir():
     return str(Path(__file__).parent / "cassettes" / "test_reranker")
 
 
-@pytest.fixture(autouse=True)
-def clear_reranker_cache():
-    """Clear the reranker cache before each test."""
-    _reranker_cache.clear()
-    yield
-    _reranker_cache.clear()
-
-
 chunks = [
     Chunk(content=content, document_id=str(i))
     for i, content in enumerate(
@@ -202,24 +194,6 @@ class TestGetReranker:
         except ImportError:
             pytest.skip("Zero Entropy package not installed")
 
-    def test_caching_returns_same_instance(self):
-        config = AppConfig(reranking=RerankingConfig(model=None))
-        result1 = get_reranker(config)
-        result2 = get_reranker(config)
-        assert result1 is result2
-
-    def test_different_configs_get_separate_cache_entries(self):
-        config1 = AppConfig(reranking=RerankingConfig(model=None))
-        config2 = AppConfig(reranking=RerankingConfig(model=None))
-
-        result1 = get_reranker(config1)
-        result2 = get_reranker(config2)
-
-        # Both return None, but they should be cached separately
-        assert result1 is None
-        assert result2 is None
-        assert len(_reranker_cache) == 2
-
     def test_unknown_provider_returns_none(self):
         config = AppConfig(
             reranking=RerankingConfig(