What does it mean that sub-agents use a 5 min cache? Is this just for growing contexts submitted by subagent itself? What about fixed sub-agent context prefixes such as tool definitions? Are those 1hr TTL?
It seems that a more flexible cache control mechanism, useful for variable duration sub-agents, would be more like an arena allocator. Let the client tag their API key activity with different "cache group" (arena) identifiers, then provide an API method to let them free each cache group when they are finished with it. Each sub-agent would then use it's own cache group and clear it when the sub-agent exits, rather than just having a fixed 5min or 1hr TTL. The client could provide a default TTL for each cache group to use in case they forget to free.
Context prefixes like tool definitions that will be the same for multiple invocations of the same sub-agent type could then be created (maybe by main agent) with a different cache group, and a longer default TTL.
It seems that a more flexible cache control mechanism, useful for variable duration sub-agents, would be more like an arena allocator. Let the client tag their API key activity with different "cache group" (arena) identifiers, then provide an API method to let them free each cache group when they are finished with it. Each sub-agent would then use it's own cache group and clear it when the sub-agent exits, rather than just having a fixed 5min or 1hr TTL. The client could provide a default TTL for each cache group to use in case they forget to free.
Context prefixes like tool definitions that will be the same for multiple invocations of the same sub-agent type could then be created (maybe by main agent) with a different cache group, and a longer default TTL.