Deep Agents Adds Tool Binding, Pinned Skills, and Skill Reloading

LangChain revamped skills support in Deep Agents with three changes: tools bound to a skill load only when the agent reads that skill, pinned skills are loaded before the next model call when a user requests them, and long-running threads can pick up new or changed skills without restarting.

Each skill is a folder with a SKILL.md file, and only its name and description are in context until the agent reads the full instructions.