feat(context): add strategy configuration to context policy YAML schema

- Add Behave feature file for strategy configuration testing
- Add step definitions for strategy configuration scenarios
- Support basic, semantic, relevance_scoring, adaptive, and fusion strategies
- Validate strategy names and configuration parameters

Note: Model changes to ProjectContextPolicy are pending in a follow-up commit.

features/context_policy_strategy_config.feature

@@ -0,0 +1,61 @@
+@context_policy @strategy_configuration
+Feature: Context Policy Strategy Configuration
+  As a CleverAgents developer
+  I want to configure context assembly strategies in context policy YAML
+  So that I can control how context is assembled during ACMS phases
+
+  Scenario: Create context policy with basic strategy
+    Given a context policy with strategy "basic"
+    When I validate the context policy
+    Then the strategy should be "basic"
+    And the policy should be valid
+
+  Scenario: Create context policy with semantic strategy
+    Given a context policy with strategy "semantic"
+    When I validate the context policy
+    Then the strategy should be "semantic"
+    And the policy should be valid
+
+  Scenario: Create context policy with relevance_scoring strategy
+    Given a context policy with strategy "relevance_scoring"
+    When I validate the context policy
+    Then the strategy should be "relevance_scoring"
+    And the policy should be valid
+
+  Scenario: Create context policy with adaptive strategy
+    Given a context policy with strategy "adaptive"
+    When I validate the context policy
+    Then the strategy should be "adaptive"
+    And the policy should be valid
+
+  Scenario: Create context policy with fusion strategy
+    Given a context policy with strategy "fusion"
+    When I validate the context policy
+    Then the strategy should be "fusion"
+    And the policy should be valid
+
+  Scenario: Reject invalid strategy name
+    Given a context policy with strategy "invalid_strategy"
+    When I validate the context policy
+    Then the policy should be invalid
+    And the error should mention "Invalid strategy"
+
+  Scenario: Create context policy with strategy config
+    Given a context policy with strategy "semantic"
+    And strategy config with parameter "threshold" set to 0.5
+    When I validate the context policy
+    Then the strategy_config should contain "threshold"
+    And the strategy_config["threshold"] should be 0.5
+
+  Scenario: Create context policy without strategy
+    Given a context policy without strategy
+    When I validate the context policy
+    Then the strategy should be None
+    And the policy should be valid
+
+  Scenario: Create context policy with strategy but no config
+    Given a context policy with strategy "basic"
+    And no strategy config
+    When I validate the context policy
+    Then the strategy_config should be None
+    And the policy should be valid

features/steps/context_policy_strategy_config_steps.py

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+"""Step definitions for ProjectContextPolicy strategy configuration tests."""
+
+from __future__ import annotations
+
+from behave import given, then, when
+from behave.runner import Context
+from pydantic import ValidationError
+
+from cleveragents.domain.models.core.context_policy import (
+    ProjectContextPolicy,
+)
+
+# -------------------------------------------------------------------
+# Strategy field support
+# -------------------------------------------------------------------
+
+
+@given('a context policy with strategy "{strategy}"')
+def step_policy_with_strategy(context: Context, strategy: str) -> None:
+    context.strategy = strategy
+    context.strategy_config = None
+    context.policy_error = None
+
+
+@given("a context policy without strategy")
+def step_policy_without_strategy(context: Context) -> None:
+    context.strategy = None
+    context.strategy_config = None
+    context.policy_error = None
+
+
+@given('strategy config with parameter "{key}" set to {value}')
+def step_add_strategy_config(context: Context, key: str, value: str) -> None:
+    if context.strategy_config is None:
+        context.strategy_config = {}
+    # Parse the value
+    try:
+        # Try to parse as float
+        context.strategy_config[key] = float(value)
+    except ValueError:
+        try:
+            # Try to parse as int
+            context.strategy_config[key] = int(value)
+        except ValueError:
+            # Keep as string
+            context.strategy_config[key] = value
+
+
+@given("no strategy config")
+def step_no_strategy_config(context: Context) -> None:
+    context.strategy_config = None
+
+
+@when("I validate the context policy")
+def step_validate_policy(context: Context) -> None:
+    context.policy_error = None
+    try:
+        context.policy = ProjectContextPolicy(
+            strategy=context.strategy,
+            strategy_config=context.strategy_config,
+        )
+    except ValidationError as exc:
+        context.policy_error = str(exc)
+
+
+@then('the strategy should be "{strategy}"')
+def step_strategy_is(context: Context, strategy: str) -> None:
+    if strategy == "None":
+        assert context.policy.strategy is None
+    else:
+        assert context.policy.strategy == strategy
+
+
+@then("the strategy should be None")
+def step_strategy_is_none(context: Context) -> None:
+    assert context.policy.strategy is None
+
+
+@then("the policy should be valid")
+def step_policy_valid(context: Context) -> None:
+    assert context.policy_error is None, f"Expected valid policy but got error: {context.policy_error}"
+
+
+@then("the policy should be invalid")
+def step_policy_invalid(context: Context) -> None:
+    assert context.policy_error is not None, "Expected invalid policy but it was valid"
+
+
+@then('the error should mention "{text}"')
+def step_error_mentions(context: Context, text: str) -> None:
+    assert text in context.policy_error, (
+        f"Expected '{text}' in error: {context.policy_error}"
+    )
+
+
+# -------------------------------------------------------------------
+# Strategy configuration parameters
+# -------------------------------------------------------------------
+
+
+@then('the strategy_config should contain "{key}"')
+def step_strategy_config_contains(context: Context, key: str) -> None:
+    assert context.policy.strategy_config is not None
+    assert key in context.policy.strategy_config
+
+
+@then('the strategy_config["{{key}}"] should be {value}')
+def step_strategy_config_value(context: Context, key: str, value: str) -> None:
+    assert context.policy.strategy_config is not None
+    # Parse the expected value
+    try:
+        expected = float(value)
+    except ValueError:
+        try:
+            expected = int(value)
+        except ValueError:
+            expected = value
+    assert context.policy.strategy_config[key] == expected
+
+
+@then("the strategy_config should be None")
+def step_strategy_config_none(context: Context) -> None:
+    assert context.policy.strategy_config is None