The bridge now holds each session's `AgentHandle` disposer in its
`SessionRecord` and runs it on teardown (client disconnect or fiber dispose)
instead of the old `abort()` + `whenIdle()` drain that left agents
registered. A bare client disconnect now leaves NO registered agent and NO
session-store entry — not an idled-but-still-registered one. The queue-aware
`cancel()` inside the disposer also closes the former pre-step best-effort
window (a turn about to start is dropped), so teardown reaches true
quiescence.
The `session/load`-races-teardown leak is fixed: if the bridge closed while
`resume()` was pending, the just-resumed handle is disposed before throwing,
so it leaves no orphan (it has no SessionRecord, so quiesce() never sees it).
Tests: the disconnect test now asserts (through the SAME memoized teardown)
that the agent is unregistered AND its session removed; a durability test
re-loads the persisted log after dispose and asserts the closing turn/end is
on disk (guards the teardown-order contract); a sibling-isolation test proves
one handle's dispose() leaves other agents untouched. Docs: agent /
agent-loop / acp READMEs, architecture.md, and the stale in-code quiesce()
ownership comment updated to the per-agent disposal model; the now-resolved
TODO(rfc010-agent-disposal) / TODO(rfc010-cancel-prestep) teardown notes
removed.
Tianyi Cui
ee4cad3ada