Feature: DevcontainerHandler missing protocol methods
  As a developer using DevcontainerHandler
  I want delete(), list_children(), diff(), and create_sandbox() to be implemented
  So that the handler satisfies the full ResourceHandler protocol (issue #1242)

  # ── delete() method ─────────────────────────────────────────

  Scenario: dcproto delete file successfully from devcontainer
    Given dcproto a devcontainer handler
    And dcproto a devcontainer-instance resource with location "/ws/project"
    And dcproto subprocess returns successful rm output
    When dcproto I delete path "src/old_file.py" from the resource
    Then dcproto the delete should succeed
    And dcproto the delete message should contain "src/old_file.py"
    And dcproto the subprocess should have been called with "rm" and "src/old_file.py"

  Scenario: dcproto delete with empty path targets workspace root
    Given dcproto a devcontainer handler
    And dcproto a devcontainer-instance resource with location "/ws/project"
    And dcproto subprocess returns successful rm output
    When dcproto I delete with empty path from the resource
    Then dcproto the delete should succeed
    And dcproto the subprocess should have been called with "rm" and "."

  Scenario: dcproto delete fails when container is stopped
    Given dcproto a devcontainer handler
    And dcproto a devcontainer-instance resource with location "/ws/project"
    And dcproto subprocess returns failed rm output with stderr "container not running"
    When dcproto I delete path "file.txt" from the resource
    Then dcproto the delete should fail
    And dcproto the delete failure message should contain "container not running"

  Scenario: dcproto delete from resource with no location raises ValueError
    Given dcproto a devcontainer handler
    And dcproto a devcontainer-instance resource with no location
    When dcproto I delete path "any/file.txt" from the resource
    Then dcproto the delete should raise ValueError containing "no location"

  # ── list_children() method ───────────────────────────────────

  Scenario: dcproto list_children returns sorted names from devcontainer
    Given dcproto a devcontainer handler
    And dcproto a devcontainer-instance resource with location "/ws/project"
    And dcproto subprocess returns successful ls listing "src\ntests\nREADME.md"
    When dcproto I list children of the resource
    Then dcproto the children list should have 3 entries
    And dcproto the children list should be "README.md,src,tests"

  Scenario: dcproto list_children returns empty list when container is stopped
    Given dcproto a devcontainer handler
    And dcproto a devcontainer-instance resource with location "/ws/project"
    And dcproto subprocess returns failed ls output
    When dcproto I list children of the resource
    Then dcproto the children list should have 0 entries

  Scenario: dcproto list_children filters blank lines from ls output
    Given dcproto a devcontainer handler
    And dcproto a devcontainer-instance resource with location "/ws/project"
    And dcproto subprocess returns successful ls listing "alpha\n\n\nbeta\n"
    When dcproto I list children of the resource
    Then dcproto the children list should have 2 entries
    And dcproto the children list should be "alpha,beta"

  Scenario: dcproto list_children from resource with no location raises ValueError
    Given dcproto a devcontainer handler
    And dcproto a devcontainer-instance resource with no location
    When dcproto I list children of the resource
    Then dcproto the list children should raise ValueError containing "no location"

  Scenario: dcproto list_children uses devcontainer exec ls command
    Given dcproto a devcontainer handler
    And dcproto a devcontainer-instance resource with location "/ws/project"
    And dcproto subprocess returns successful ls listing "main.py"
    When dcproto I list children of the resource
    Then dcproto the subprocess should have been called with "ls" and "--workspace-folder"

  # ── diff() method ────────────────────────────────────────────

  Scenario: dcproto diff detects changes when hashes differ
    Given dcproto a devcontainer handler
    And dcproto a devcontainer-instance resource with location "/ws/project"
    And dcproto the container content hash is "aabbccdd"
    And dcproto a temporary directory with a different file
    When dcproto I diff the resource against the temporary directory
    Then dcproto the diff should report has_changes true
    And dcproto the diff files_changed should be 1

  Scenario: dcproto diff reports no changes when hashes match
    Given dcproto a devcontainer handler
    And dcproto a devcontainer-instance resource with location "/ws/project"
    And dcproto the container content hash matches the other location
    When dcproto I diff the resource against the same location
    Then dcproto the diff should report has_changes false
    And dcproto the diff files_changed should be 0

  Scenario: dcproto diff reports no changes when both sides are absent
    Given dcproto a devcontainer handler
    And dcproto a devcontainer-instance resource with location "/nonexistent/path"
    When dcproto I diff the resource against "/another/nonexistent/path"
    Then dcproto the diff should report has_changes false

  Scenario: dcproto diff from resource with no location raises ValueError
    Given dcproto a devcontainer handler
    And dcproto a devcontainer-instance resource with no location
    When dcproto I diff the resource against "/some/path"
    Then dcproto the diff should raise ValueError containing "no location"

  Scenario: dcproto diff unified_diff is always empty string
    Given dcproto a devcontainer handler
    And dcproto a devcontainer-instance resource with location "/ws/project"
    And dcproto the container content hash is "aabbccdd"
    And dcproto a temporary directory with a different file
    When dcproto I diff the resource against the temporary directory
    Then dcproto the diff unified_diff should be empty

  # ── create_sandbox() method ──────────────────────────────────

  Scenario: dcproto create_sandbox delegates to base class for running container
    Given dcproto a devcontainer handler
    And dcproto a devcontainer-instance resource with location "/ws/project"
    And dcproto the container is in RUNNING state
    And dcproto a mock sandbox manager that returns a valid sandbox
    When dcproto I create a sandbox for the resource with plan "plan-001"
    Then dcproto the sandbox result should have strategy "snapshot"
    And dcproto the sandbox result should have a sandbox path

  Scenario: dcproto create_sandbox activates container when in DISCOVERED state
    Given dcproto a devcontainer handler
    And dcproto a devcontainer-instance resource with location "/ws/project"
    And dcproto the container is in DISCOVERED state
    And dcproto a mock sandbox manager that returns a valid sandbox
    And dcproto activate_container is mocked to succeed
    When dcproto I create a sandbox for the resource with plan "plan-002"
    Then dcproto activate_container should have been called

  Scenario: dcproto create_sandbox activates container when in STOPPED state
    Given dcproto a devcontainer handler
    And dcproto a devcontainer-instance resource with location "/ws/project"
    And dcproto the container is in STOPPED state
    And dcproto a mock sandbox manager that returns a valid sandbox
    And dcproto activate_container is mocked to succeed
    When dcproto I create a sandbox for the resource with plan "plan-003"
    Then dcproto activate_container should have been called

  Scenario: dcproto create_sandbox raises ValueError for resource with no location
    Given dcproto a devcontainer handler
    And dcproto a devcontainer-instance resource with no location
    And dcproto a mock sandbox manager that returns a valid sandbox
    When dcproto I create a sandbox for the resource with plan "plan-004"
    Then dcproto the create_sandbox should raise ValueError containing "no location"