A preset registers its tools into the agent's OWN layer, so `session.history`
served while no agent exists found no presenter at all and every card degraded
to the generic renderer — silently, because a viewless entry is also what a
tool with no presenter produces. The web client opens a session by reading its
transcript, so this was the ordinary path, not an edge: the write row lost its
diff card, and with it the `locations` the produced-files row derives from.
The read now resolves the agent through the same deduplicated resume every
other session method takes, but only when a roster is composed: a deployment
without presets keeps its tools on the host layer, which needs no agent to
address, and keeps the storage-only read unchanged. A resolution failure stays
a successful read.
Yichen Jiang
1c80023b12