fix(test): move advanced context strategy test doubles to features/mocks

- Extract FakeEmbeddings, RelevanceScoringStrategy, AdaptiveContextSelector,
  ContextFusionStrategy, and _pack_budget from features/steps/ into new
  features/mocks/advanced_context_strategies_mocks.py per mock-placement rules
- Remove sys.path manipulation from robot/helper_advanced_context_strategies.py;
  import directly from features.mocks instead of features/steps
- Add None guard before selected.assemble() in step_assemble_context_query
- Add explicit ValueError for unknown strategy types in step_load_yaml_strategy
  and load_strategy_from_yaml_impl

ISSUES CLOSED: #7574

robot/helper_advanced_context_strategies.py

@@ -2,10 +2,14 @@
 
 from __future__ import annotations
 
-import sys
-from pathlib import Path
 from typing import Any
 
+from features.mocks.advanced_context_strategies_mocks import (
+    AdaptiveContextSelector,
+    ContextFusionStrategy,
+    RelevanceScoringStrategy,
+)
+
 from cleveragents.application.services.context_strategies import (
     BreadthDepthNavigatorStrategy,
     SemanticEmbeddingStrategy,
@@ -19,16 +23,6 @@ from cleveragents.domain.models.core.context_fragment import (
 # Default provenance used for test fragments (no real resource needed).
 _TEST_PROVENANCE = FragmentProvenance(resource_uri="test://fixture")
 
-# Import from step definitions
-features_path = Path(__file__).parent.parent / "features" / "steps"
-sys.path.insert(0, str(features_path))
-
-from advanced_context_strategies_steps import (  # noqa: E402
-    AdaptiveContextSelector,
-    ContextFusionStrategy,
-    RelevanceScoringStrategy,
-)
-
 
 def create_semantic_search_strategy_impl() -> SemanticEmbeddingStrategy:
     """Create a semantic search strategy with FakeEmbeddings."""
@@ -80,9 +74,7 @@ def create_test_fragments_impl(args: list[str]) -> list[ContextFragment]:
     return fragments
 
 
-def create_context_budget_impl(
-    max_tokens: int, reserved_tokens: int
-) -> ContextBudget:
+def create_context_budget_impl(max_tokens: int, reserved_tokens: int) -> ContextBudget:
     """Create a context budget."""
     return ContextBudget(
         max_tokens=int(max_tokens),
@@ -159,8 +151,8 @@ def load_strategy_from_yaml_impl(config: dict[str, Any]) -> Any:
     elif strategy_type == "context-fusion":
         strategies = config.get("strategies", [])
         return ContextFusionStrategy(strategies)
-
-    return None
+    else:
+        raise ValueError(f"Unknown strategy type: {strategy_type!r}")
 
 
 def create_context_assembler_with_advanced_strategies_impl() -> dict[str, Any]:
@@ -193,7 +185,6 @@ def assemble_context_with_query_impl(
     """Assemble context with a query."""
     request = {"query": query}
 
-    # Select best strategy
     best_strategy = None
     best_confidence = 0.0
 
@@ -206,7 +197,6 @@ def assemble_context_with_query_impl(
     if best_strategy is None:
         best_strategy = assembler["strategies"][0]
 
-    # Set query if needed
     if hasattr(best_strategy, "set_query"):
         best_strategy.set_query(query)