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LocalAI/docs/content
Ettore Di Giacinto a6b2d7c0ec fix(distributed): read a departed agent tunnel as the routing fact it is
Task 4 gave agent workers tunnels and deliberately left the NodeType skip in
HealthMonitor.tunnelDeparted, with a spec asserting that an agent node whose
presence reader answers PresenceGone is NOT marked unhealthy. That spec was
scaffolding. It was true while an agent worker took its jobs and its verbs over
the message bus: a departure row for one said nothing about whether it could
work, and an early bug in the new tunnel client could otherwise have demoted a
fleet of healthy agent workers.

There is no bus. An agent worker is reachable through its tunnel and through
nothing else, so a departed agent tunnel means exactly what a departed backend
tunnel means: no live replica holds it, the departure has outlived the reconnect
grace, and that is a routing fact the scheduler and a reaper may act on. The
skip would now hide the only symptom an unreachable agent worker has. This is
the deliberate removal Task 4's M6 predicted, and task-4-report.md is where that
mutation already stands recorded red against the spec this commit deletes.

The skip existed at ONE site. router_liveness.go has none: its candidates come
from queries that already filter node_type = 'backend'. The two skips in
managers_distributed.go stay, because an agent worker still runs no backend
processes, so it has no backend to list and no backend op to apply.

Two node types can depart now, which is why the second half exists. Before this,
one type could depart and every per-node cache a departure left stale was
dropped from wherever its owner happened to notice, so a reader could not tell
which caches a demotion invalidated by reading the demotion path. Departure gets
ONE notification point. DepartureNotifier is edge triggered, because the monitor
runs on a ticker and a departed node stays departed; its subscribers are NAMED,
because what has to be caught is a forgotten cache and a count can say only that
one of four is missing; and NewHealthMonitor takes it as a required positional
argument, so a caller that does not pass one fails to compile.

Four caches subscribe: prefix-cache affinity in every model, probe freshness at
every address, in-flight staging operations, and the per-node breakdown of every
open gallery operation. The prefix-cache one is registered only when
prefix-cache routing is enabled, so --distributed-prefix-cache=false stays a
true no-op. The notification carries the node's name as well as its id, because
the staging tracker keys on the name and the other two key on the id, and a
subscriber should not have to read the registry from inside an eviction hook.

A departure notification is an act on absence, so it fires only on the routing
fact. A tunnel lost inside the grace, a worker that never dialled, a presence
query that failed and a stale heartbeat all announce nothing, asserted per node
type. The stale-heartbeat branch is excluded on purpose: it already marks the
node offline, which deletes its rows and runs the registry's replica-removed
hooks, so firing there too would double-evict and make the notification mean two
different things at its subscribers.

Assisted-by: Claude Opus 5 [claude-code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
2026-09-04 06:33:14 +00:00
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