Feature: Plan diff and artifacts CLI command coverage
  As a developer
  I want to cover the plan diff, plan artifacts CLI commands and remaining branches
  So that plan.py lines 1815-1888 and missing branches are fully covered

  # ---------- plan diff CLI command (lines 1845-1855) ----------

  Scenario: plan_diff_artifacts successful diff prints output
    Given plan_diff_artifacts the apply service returns diff output "--- a/file.py\n+++ b/file.py"
    When plan_diff_artifacts I run the diff subcommand for plan "plan-001"
    Then plan_diff_artifacts the exit code should be 0
    And plan_diff_artifacts the output should contain "file.py"

  Scenario: plan_diff_artifacts diff with custom format
    Given plan_diff_artifacts the apply service returns diff output '{"entries": []}'
    When plan_diff_artifacts I run the diff subcommand for plan "plan-002" using format "json"
    Then plan_diff_artifacts the exit code should be 0
    And plan_diff_artifacts the output should contain "entries"

  Scenario: plan_diff_artifacts diff raises PlanError
    Given plan_diff_artifacts the apply service diff raises a PlanError "changeset not found"
    When plan_diff_artifacts I run the diff subcommand for plan "plan-bad"
    Then plan_diff_artifacts the command should be aborted
    And plan_diff_artifacts the output should contain "Diff Error"
    And plan_diff_artifacts the output should contain "changeset not found"

  Scenario: plan_diff_artifacts diff raises CleverAgentsError
    Given plan_diff_artifacts the apply service diff raises a CleverAgentsError "service unavailable"
    When plan_diff_artifacts I run the diff subcommand for plan "plan-err"
    Then plan_diff_artifacts the command should be aborted
    And plan_diff_artifacts the output should contain "Error"
    And plan_diff_artifacts the output should contain "service unavailable"

  # ---------- plan artifacts CLI command (lines 1878-1888) ----------

  Scenario: plan_diff_artifacts successful artifacts prints output
    Given plan_diff_artifacts the apply service returns artifacts output "changeset-id: cs-001"
    When plan_diff_artifacts I run the artifacts subcommand for plan "plan-001"
    Then plan_diff_artifacts the exit code should be 0
    And plan_diff_artifacts the output should contain "cs-001"

  Scenario: plan_diff_artifacts artifacts with custom format
    Given plan_diff_artifacts the apply service returns artifacts output '{"changeset_id": "cs-002"}'
    When plan_diff_artifacts I run the artifacts subcommand for plan "plan-003" using format "json"
    Then plan_diff_artifacts the exit code should be 0
    And plan_diff_artifacts the output should contain "cs-002"

  Scenario: plan_diff_artifacts artifacts raises PlanError
    Given plan_diff_artifacts the apply service artifacts raises a PlanError "plan not found"
    When plan_diff_artifacts I run the artifacts subcommand for plan "plan-missing"
    Then plan_diff_artifacts the command should be aborted
    And plan_diff_artifacts the output should contain "Artifacts Error"
    And plan_diff_artifacts the output should contain "plan not found"

  Scenario: plan_diff_artifacts artifacts raises CleverAgentsError
    Given plan_diff_artifacts the apply service artifacts raises a CleverAgentsError "timeout"
    When plan_diff_artifacts I run the artifacts subcommand for plan "plan-timeout"
    Then plan_diff_artifacts the command should be aborted
    And plan_diff_artifacts the output should contain "Error"
    And plan_diff_artifacts the output should contain "timeout"

  # ---------- _get_apply_service (lines 1815-1822) ----------

  Scenario: plan_diff_artifacts _get_apply_service creates PlanApplyService
    Given plan_diff_artifacts a mock lifecycle service
    When plan_diff_artifacts I call _get_apply_service
    Then plan_diff_artifacts a PlanApplyService should be returned

  # ---------- build command branch: no actor_registry (L646->648) ----------

  Scenario: plan_diff_artifacts build command without actor registry
    Given plan_diff_artifacts a container without actor_registry
    When plan_diff_artifacts I invoke the build command
    Then plan_diff_artifacts the build should complete without actor registry calls

  # ---------- build command branch: testing_mode disabled (L648->652) ----------

  Scenario: plan_diff_artifacts build command with testing mode disabled
    Given plan_diff_artifacts a container with actor_registry but testing mode disabled
    When plan_diff_artifacts I invoke the build command
    Then plan_diff_artifacts ensure_default_mock_actor should not be called

  # ---------- plan show: arguments_order with extra key (L1130->1129) ----------

  Scenario: plan_diff_artifacts plan show with arguments_order containing missing key
    Given plan_diff_artifacts a lifecycle plan with arguments_order having an extra key
    When plan_diff_artifacts I print the lifecycle plan
    Then plan_diff_artifacts the output should contain the valid argument
    And plan_diff_artifacts the output should not contain the missing key value