Skill agent metadata errors

A bundled skill can define its own interface in skills/<skill>/agents/openai.yaml. This controls how the skill appears to users and is separate from the plugin manifest's interface. Skill interface fields use snake_case:

interface:
  display_name: "Summarize documents"
  short_description: "Summarize a document"
  icon_small: "./assets/icon.png"
  default_prompt: "Summarize the selected document."

Name	Requirement
skill_agent_not_regular_file	agents/openai.yaml must be a regular file.
skill_agent_unreadable	agents/openai.yaml must be readable.
skill_agent_invalid_utf8	agents/openai.yaml must contain valid UTF-8.
skill_agent_yaml_malformed	agents/openai.yaml must contain valid YAML.
skill_agent_top_level_wrong_type	agents/openai.yaml must contain a YAML mapping at the top level.
skill_agent_interface_missing	interface is required in agents/openai.yaml when that file is included.
skill_agent_interface_wrong_type	interface in agents/openai.yaml must be a YAML mapping.
skill_agent_display_name_missing	interface.display_name is required and must not be empty.
skill_agent_display_name_wrong_type	interface.display_name must be a string.
skill_agent_display_name_empty	interface.display_name must not be empty.
skill_agent_short_description_missing	interface.short_description is required and must not be empty.
skill_agent_short_description_wrong_type	interface.short_description must be a string.
skill_agent_short_description_empty	interface.short_description must not be empty.
skill_agent_icon_small_wrong_type	interface.icon_small must be a non-empty relative file path when provided.
skill_agent_icon_small_empty	interface.icon_small must be a non-empty relative file path when provided, such as assets/icon.png.
skill_agent_icon_large_wrong_type	interface.icon_large must be a non-empty relative file path when provided.
skill_agent_icon_large_empty	interface.icon_large must be a non-empty relative file path when provided, such as assets/icon.png.
skill_agent_brand_color_wrong_type	interface.brand_color must be a string when provided.
skill_agent_brand_color_empty	interface.brand_color must be a non-empty six-digit hex color when provided, such as #1ABCFE.
skill_agent_brand_color_format	interface.brand_color must be a six-digit hex color, such as #1ABCFE.
skill_agent_default_prompt_wrong_type	interface.default_prompt must be a string when provided.
skill_agent_default_prompt_empty	interface.default_prompt must be non-empty when provided.
skill_agent_policy_wrong_type	policy must be a YAML mapping when provided.
skill_agent_allow_implicit_invocation_wrong_type	policy may contain only products and allow_implicit_invocation. products must contain CHAT, CODEX, or both, and allow_implicit_invocation must be true or false.
skill_agent_dependencies_wrong_type	dependencies must be a YAML mapping; only tools is supported.
skill_agent_dependency_unsupported	Only dependencies.tools is supported in agents/openai.yaml.