Slash commands can now finish their output after being queued and patch it into your queued message
When a local slash command's output isn't ready yet but you've already queued a message containing it, Claude Code can now go back and patch the queued message once the result arrives, rather than requiring the result up front. This works by finding a queued message that starts with <local-command-stdout> or <local-command-stderr> and rewriting its contents in place, paired with new internal helpers that build the initial placeholder message and track it by a deferredSlashUuid.
This lets a local slash command's result show up correctly even if it finishes after the message using it has already been queued for sending, instead of the message being stuck with stale or missing output.