Feature: Additional route bridge uncovered lines coverage
  As a developer
  I want to exercise uncovered branches in route bridge
  So that coverage gaps are closed

  Background:
    Given I have a clean test environment for route bridge

  Scenario: Bridge falls back to empty agents on registry failure
    Given I have a failing agent registry for route bridge
    When I create the route bridge instance
    Then the route bridge should be initialized correctly
    And the route bridge agents should be empty

  Scenario: Upgrade conditions not met when below message_count threshold
    Given I have a RouteBridge instance
    And I have a stream route config with message_count upgrade condition
    And I have a pending message count below threshold
    And I have a stream message
    When I check upgrade conditions
    Then the route bridge upgrade result should be False

  Scenario: Complexity threshold too high prevents upgrade
    Given I have a RouteBridge instance
    And I have a simple stream route config with high complexity threshold
    And I have a stream message
    When I check upgrade conditions
    Then the route bridge upgrade result should be False

  Scenario: Callable custom predicate triggers upgrade
    Given I have a RouteBridge instance
    And I have a stream route config with callable custom_predicate
    And I have a stream message
    When I check upgrade conditions synchronously
    Then the route bridge upgrade result should be True

  Scenario: Upgrade applies state extractor and preserves subscriptions loop
    Given I have a RouteBridge instance
    And I have a stream route config with state extractor and subscriptions
    And I have a stream message
    When I upgrade the stream route to graph
    Then the graph initial state should include extracted data

  Scenario: Downgrade uses flattener and checkpointing
    Given I have a RouteBridge instance
    And I have a graph route config with flattener and checkpointing
    And I have a LangGraph instance with checkpointing
    When I downgrade the graph with flattener
    Then the state flattener should run
    And the checkpoint should be saved

  Scenario: _create_graph_from_stream uses function node when no agent 
    Given I have a clean test environment for route bridge
    Given I have a RouteBridge instance
    When I create a graph config from a stream without agents
    Then the resulting graph should use function nodes

  Scenario: _get_message_count falls back to update_count attribute 
    Given I have a clean test environment for route bridge
    Given I have a RouteBridge instance
    And I seed a fallback update_count conversion
    When I get message count for a route
    Then the route bridge fallback message count should be returned

  Scenario: Downgrade conditions not met when idle time short 
    Given I have a clean test environment for route bridge
    Given I have a RouteBridge instance
    And I have a graph route config with idle_time not exceeded
    And I have a graph state
    When I check downgrade conditions
    Then the downgrade result should be False

  Scenario: Downgrade conditions not met when state size large 
    Given I have a clean test environment for route bridge
    Given I have a RouteBridge instance
    And I have a graph route config with large state size
    And I have a graph state with multiple messages
    When I check downgrade conditions
    Then the downgrade result should be False