Feature: Tool lifecycle coverage boost
  As the tool execution engine
  I need to cover edge-case branches in ToolLifecycleCache and ToolRuntime
  Including empty-cache iteration, last-tool removal, cancellation re-raise,
  None-instance execution, and no-op deactivation paths

  # ── ToolLifecycleCache.remove deletes plan entry when last tool removed ──

  Scenario: Removing the last tool from a plan deletes the plan entry
    Given I create a coverage-boost lifecycle cache
    And I have a coverage-boost mock tool instance named "builtin/only-tool"
    When I put the coverage-boost instance in cache for plan "plan-rm-1" and tool "builtin/only-tool"
    Then the coverage-boost cache should have 1 plans
    When I remove tool "builtin/only-tool" from coverage-boost cache plan "plan-rm-1"
    Then the coverage-boost cache should have 0 plans
    And the coverage-boost cache internal dict should not contain plan "plan-rm-1"

  Scenario: Removing a tool that does not exist in cache returns None
    Given I create a coverage-boost lifecycle cache
    When I remove tool "builtin/ghost" from coverage-boost cache plan "plan-rm-2"
    Then the coverage-boost remove result should be None

  # ── ToolLifecycleCache.get_plan_tools with empty cache ──────────────────

  Scenario: Getting plan tools for a plan with no activated tools returns empty list
    Given I create a coverage-boost lifecycle cache
    Then the coverage-boost plan tools for plan "plan-empty" should be an empty list

  # ── ToolRuntime.activate with ToolCancelledError ────────────────────────

  Scenario: Activating a tool that raises ToolCancelledError propagates the error
    Given I create a coverage-boost tool runtime
    And I register a coverage-boost cancelling-activate tool "builtin/cancel-act"
    And I create a coverage-boost execution context with plan_id "plan-cancel-act"
    When I try to activate the cancelling tool "builtin/cancel-act" in coverage-boost runtime
    Then a ToolCancelledError should have been raised in coverage-boost activation

  # ── ToolRuntime.execute with None cached instance ──────────────────────

  Scenario: Executing a tool when cached instance is None raises ToolNotActivatedError
    Given I create a coverage-boost tool runtime
    And I register a coverage-boost tool "builtin/null-cache" with a mock that nullifies cache
    And I create a coverage-boost execution context with plan_id "plan-null-cache"
    When I try to execute the null-cache tool "builtin/null-cache" in coverage-boost runtime
    Then a ToolNotActivatedError should have been raised in coverage-boost execution

  # ── ToolRuntime.execute with ToolCancelledError during execution ────────

  Scenario: Executing a tool that raises ToolCancelledError records trace and re-raises
    Given I create a coverage-boost tool runtime
    And I register a coverage-boost cancelling-execute tool "builtin/cancel-exec"
    And I create a coverage-boost execution context with plan_id "plan-cancel-exec"
    When I try to execute the cancelling-execute tool "builtin/cancel-exec" in coverage-boost runtime
    Then a ToolCancelledError should have been raised in coverage-boost execution
    And the coverage-boost context should have 1 traces
    And the coverage-boost last trace should show success False
    And the coverage-boost last trace error should be "Cancelled"

  # ── ToolRuntime.deactivate with tool not in cache ──────────────────────

  Scenario: Deactivating a tool that was never activated is a silent no-op
    Given I create a coverage-boost tool runtime
    And I register a coverage-boost read-only tool "builtin/never-active" with a mock
    And I create a coverage-boost execution context with plan_id "plan-deact-none"
    When I deactivate tool "builtin/never-active" in the coverage-boost runtime
    Then no coverage-boost exception should have been raised
    And the coverage-boost mock "builtin/never-active" should not have been deactivated

  # ── ToolRuntime.deactivate_plan with empty plan ────────────────────────

  Scenario: Deactivating a plan with no activated tools is a silent no-op
    Given I create a coverage-boost tool runtime
    And I create a coverage-boost execution context with plan_id "plan-deact-empty"
    When I deactivate plan in the coverage-boost runtime
    Then no coverage-boost exception should have been raised

  # ── ToolLifecycleCache.remove with multiple tools leaves remaining ─────

  Scenario: Removing one of two tools keeps the plan entry with the remaining tool
    Given I create a coverage-boost lifecycle cache
    And I have a coverage-boost mock tool instance named "builtin/tool-a"
    And I have a second coverage-boost mock tool instance named "builtin/tool-b"
    When I put the coverage-boost instance in cache for plan "plan-rm-multi" and tool "builtin/tool-a"
    And I put the second coverage-boost instance in cache for plan "plan-rm-multi" and tool "builtin/tool-b"
    Then the coverage-boost cache should have 1 plans
    When I remove tool "builtin/tool-a" from coverage-boost cache plan "plan-rm-multi"
    Then the coverage-boost cache should have 1 plans
    And the coverage-boost cache get for plan "plan-rm-multi" and tool "builtin/tool-b" should not be None