I-2: unclaimed parked events are trimmed by window sequence. Each window gets a
monotonically increasing sequence at Begin, each parked event is stamped with
the newest one, and on every End events stamped before the oldest open
window's sequence are dropped (amortised O(1) via a park-order queue). Under
concurrent reads the open count rarely hit 0, so trailing events used to pile
up to the bound and push genuine early values into overflow.
I-1 / #861: SubscriptionRegistry.StartNewSession() — called FIRST in
ReplayAsync on every reconnect — clears held events, invalidates the reverse
map (subscriptions kept) and bumps a session number. New-session events whose
number an old binding still held now park until the replay's per-subscription
Rebind promotes them, instead of resolving to the wrong tag. TryRegister /
TryRebind refuse a stale session atomically under the park gate: a
SubscribeAsync whose reply straddled a reconnect is re-issued on the new
session (max 3 attempts), a subscribe-once read returns BadCommunicationError,
ResubscribeAllAsync stops if the session changes again. Old-session handle
numbers are never unsubscribed (Remove reports whether the entry belongs to
the current session; the read's late-reply path checks too), and an old
session's pump can no longer resolve through the map (fast path checks the
session).
I-3 (interim): a completed UnsubscribeBulk purges events parked for its
handles (driver + probe watcher). Full fix needs a worker sequence on the
SubscribeBulk reply (mxaccessgw, optional) — documented.
M-1: a resolved handle with a stranded parked list promotes it and resolves
the live event (never parks it). M-2: ResolveOrPark returns the ready events
to replay first, one gate acquisition per event while anything is held.
M-3: SubscribeAsync/read dispose the window before the orphan-release RPC.
M-5: ResolveOrPark remarks document the single-dispatching-pump invariant.
Tests (TestWait): overlapping windows don't accumulate, purge, stranded list,
session fence + map invalidation, stale-session registration refused,
end-to-end replay with swapped handle numbers and event-before-reply,
subscribe and read straddling a reconnect, read deadline closes its window.
Each was checked red against a mutation of the fix it pins.
Refs #859, #861.
Claude-Session: https://claude.ai/code/session_01GT67AD99zQQqpLCVm3p7xk
Joseph Doherty
d08e900203