Boundary
The capstone is not a new layer. It is proof that the layers can coexist without collapsing back into one opaque script.
What this adds
Show the full shape.
The capstone combines the layers you built separately: host behavior, policy, task visibility, tool invocation, and eval output. The result is still tiny, but the architecture now resembles a real tool stack.
This is the moment where the abstractions stop being isolated lessons and start reading as one coherent system.
Done when
One command shows the relationship between context, tools, policy, durable state, and evaluation records.
Real-world analog
OpenHands is a useful comparison point for the full-system shape: host, tools, planning, and execution all working together.
After this
Compare the toy stack with the tooling catalog and ask which layers are local, hosted, open, governed, or extensible.
If you want the next late-stage jump, continue to the persistent-platform stretch goal and build a toy assistant platform that bundles the same layers the way OpenClaw and Hermes-style systems do.