Plugins are add-ons that give Claude Code extra commands, skills or tools. Some of Claude Code's behaviour is controlled by feature flags, which are on/off switches that Anthropic's servers can send. When Claude Code starts, it uses a saved copy of the claude-platform flag, or a built-in default if there is no saved copy. Later it fetches the current value from the server.
If the fetched value differs from the start-up value, Claude Code now reloads your plugins. If it cannot reload them, or holds the reload back, it says so, for example "reload held, run /reload-plugins to apply it". Running /reload-plugins brings the plugin list up to date without restarting.
Without this, the plugin list could stay out of date after the flag changes for the rest of the run.