Gate r2: resetting last_bot_poll after a started delivery never re-polled early (the next
tick re-probes while the turn is still running), so the plumbing is gone and the 5 s cadence
is stated plainly. test_shared_session_attach denied inspection for the test's own pid, which
the self-pid skip (#108005) legitimately never probes — it now denies a foreign owner.
The attach-refusal message framed an unimplemented capability as a property
of the live owner ("does not advertise cooperative attachment"), sending users
looking for a setting that does not exist. Follow the shared owner-refusal
contract instead: first line states the chat is open elsewhere and names the
working alternative (close it there, hermes --resume <id> here), second line
keeps the Details: owner summary. Same shape when the handshake itself fails.
Fixes#113457
(cherry picked from commit 78966577102f3db1383a162f526394d8af757a38)
Fence owner discovery by profile, lease and loopback endpoint, and hand the authenticated URL to the existing Ink transport without acquiring a competing lease. Distinguish lease age from turn activity in unsupported-owner recovery.
Client slice only: requires the integration runtime to advertise shared_runtime_url and provide the session-attach handshake. Classic CLI attachment remains an integration gap.
