`client.ask` and `client.analyze` built their capability from a db_path, so the
capability opened a second connection to the database the client already had
open, once per call.
Ownership is now explicit rather than inferred. `rag` stays the connection the
capability opened and must close; `borrowed_rag` is a caller's, which
`_ensure_rag` prefers and `_close` never touches. Two fields rather than a flag,
so closing a borrowed connection is not expressible.
`for_run` still clears `rag` per run, since a run owns what it opens. It leaves
`borrowed_rag` alone: that connection belongs to the caller and outlives the run.
`CapabilityEvidenceRecord` holds the relationships a transcript cannot express:
which chunks a capability retrieved, which it cited, in which questions, and at
which point in the conversation. RAG and analysis each own one in their own state
namespace. Nothing is co-written: the host's state is JSON storage, so a shared
record would be overwritten by whichever capability synced last, and merging
happens in transient per-request views instead.
Both clocks are derived from the conversation rather than counted locally, so
every participant computes the same values without sharing a counter. Question
identity is the message count when the question arrived; epoch is the message
count at an outcome. Epochs are therefore globally comparable, which is what
lets `citation_status` require a declaration to follow the newest evidence of
every capability, and what makes equal epochs mean one request.
A declaration is written only after `resolve_citations` succeeds, so a call
naming only unresolvable ids is not a citation. Status is derived, never stored,
so refs and status cannot contradict.
Resuming a question requires the host to carry the capability state from the run
being resumed. Without it the identity of the question in progress is unknowable,
and adopting the current message count would relabel that question as a new one
and judge every declaration in it against the wrong identity.
Nothing reads the records yet and no wire behaviour changes.
