feat(skill): add agent skills loader
Implemented AgentSkillSpec loader that parses SKILL.md frontmatter and
progressive disclosure sections (discover/activate/deactivate) into
structured SkillStep objects with stable 1-based ordering.
Mapped Agent Skills to AgentSkillToolDescriptor with namespaced naming
(namespace/short_name), source="agent_skill", read-only defaults, and
AgentSkillResourceSlot bindings for scripts/, references/, and assets/
directories. All resource slots are unconditionally read_only.
Added explicit validation for missing frontmatter fields (name,
description) and invalid namespace format with actionable error messages.
Added docs/reference/agent_skills.md covering folder layout, SKILL.md
parsing rules, progressive disclosure model, and tool mapping.
Added Behave scenarios covering valid/invalid SKILL.md parsing,
namespaced naming, step ordering, missing frontmatter errors, progressive
disclosure lifecycle, tool mapping, and resource binding slots.
Added Robot Framework integration tests using the deploy-to-staging
example skill folder (robot/agent_skills_loader.robot).
Added ASV benchmarks for parsing throughput, folder load, progressive
disclosure lifecycle, and resource listing
(benchmarks/agent_skills_loader_bench.py).
ISSUES CLOSED: #160
aditya
cb82fc51df
