tact-subagents

tact-subagents provides structured child-agent orchestration for Nanocodex applications. It owns clean child sessions, a scoped task tree, bounded concurrent turns, directed messages, structured result validation, and lifecycle tools.

The crate exposes three integration boundaries:

• Subagents owns one in-process runtime. Its weak handle installs Nanocodex tools without creating an ownership cycle.
• ScopedAgentUpdate is the observation stream for lifecycle, model, and message events.
• RootAgentAuthority lets an application restrict its own tools to coordinating root sessions.

Create one runtime for each root agent configuration. Drain its update receiver continuously, configure a factory that creates a fresh Nanocodex session for each child, and call Subagents::downgrade before capturing the handle in the root builder's tool factory. Call WeakSubagents::install_tools there. The same tool factory is inherited by child sessions, which permits nested delegation while the runtime enforces task-tree authority.

The runtime is process-local. It does not persist live child sessions, isolate filesystem access, or provide a distributed job queue. Root and child sessions use the process and tool authority granted by the embedding application.

See the Tact subagent design for the complete lifecycle, messaging, and failure contracts.