diff --git a/src/contextweaver/_utils.py b/src/contextweaver/_utils.py
index fdd1ff7..fedcfaa 100644
--- a/src/contextweaver/_utils.py
+++ b/src/contextweaver/_utils.py
@@ -200,8 +200,6 @@ def jaccard(a: set[str], b: set[str]) -> float:
     if not a and not b:
         return 0.0
     union = a | b
-    if not union:
-        return 0.0
     return len(a & b) / len(union)
 
 
diff --git a/src/contextweaver/config.py b/src/contextweaver/config.py
index 372dd41..91c91b6 100644
--- a/src/contextweaver/config.py
+++ b/src/contextweaver/config.py
@@ -7,7 +7,7 @@
 from __future__ import annotations
 
 from dataclasses import dataclass, field
-from typing import Any
+from typing import Any, Literal
 
 from contextweaver.types import ItemKind, Phase, Sensitivity
 
@@ -114,7 +114,7 @@ class ContextPolicy:
     max_items_per_kind: dict[ItemKind, int] = field(
         default_factory=lambda: {k: 50 for k in ItemKind}
     )
-    ttl_behavior: str = "drop"
+    ttl_behavior: Literal["drop", "warn"] = "drop"
     sensitivity_floor: Sensitivity = Sensitivity.confidential
     redaction_hooks: list[str] = field(default_factory=list)
     extra: dict[str, Any] = field(default_factory=dict)
diff --git a/src/contextweaver/context/manager.py b/src/contextweaver/context/manager.py
index 2b3c934..46f4aa2 100644
--- a/src/contextweaver/context/manager.py
+++ b/src/contextweaver/context/manager.py
@@ -89,6 +89,7 @@ def __init__(
         self._scoring = scoring_config or ScoringConfig()
         self._estimator: TokenEstimator = estimator or CharDivFourEstimator()
         self._hook: EventHook = hook or NoOpHook()
+        self._fact_counter: int = 0
 
     # ------------------------------------------------------------------
     # Properties
@@ -290,7 +291,8 @@ def add_fact(self, key: str, value: str, metadata: dict[str, Any] | None = None)
             value: Fact value.
             metadata: Optional metadata dict.
         """
-        fact_id = f"fact:{key}:{len(self._fact_store.all())}"
+        self._fact_counter += 1
+        fact_id = f"fact:{key}:{self._fact_counter}"
         self._fact_store.put(
             Fact(
                 fact_id=fact_id,
diff --git a/src/contextweaver/protocols.py b/src/contextweaver/protocols.py
index e229cf4..978bec0 100644
--- a/src/contextweaver/protocols.py
+++ b/src/contextweaver/protocols.py
@@ -121,10 +121,6 @@ def exists(self, handle: str) -> bool:
         """Return ``True`` if *handle* is in the store."""
         ...
 
-    def metadata(self, handle: str) -> ArtifactRef:
-        """Return the :class:`~contextweaver.types.ArtifactRef` for *handle*."""
-        ...
-
     def drilldown(self, handle: str, selector: dict[str, Any]) -> str:
         """Return a subset of the artifact's content according to *selector*."""
         ...
diff --git a/src/contextweaver/routing/router.py b/src/contextweaver/routing/router.py
index ff321bc..ca9377b 100644
--- a/src/contextweaver/routing/router.py
+++ b/src/contextweaver/routing/router.py
@@ -88,6 +88,7 @@ def __init__(
         self._items: dict[str, SelectableItem] = {}
         self._scorer = scorer
         self._indexed = False
+        self._doc_id_to_idx: dict[str, int] = {}
         if items is not None:
             self.set_items(items)
 
@@ -124,7 +125,7 @@ def _ensure_index(self) -> None:
                 doc_ids.append(node_id)
 
         self._scorer.fit(docs)
-        self._doc_id_to_idx: dict[str, int] = {did: i for i, did in enumerate(doc_ids)}
+        self._doc_id_to_idx = {did: i for i, did in enumerate(doc_ids)}
         self._indexed = True
 
     def _score_node(self, query: str, node_id: str) -> float: