ApplyAndAck advanced _currentRevision and recorded NodeDeploymentState=Applied
immediately after ReconcileDrivers, which returns null when the artifact could
not be read. So a node that applied NOTHING reported success, claimed a
revision whose configuration it never applied, and — because
HandleDispatchFromSteady short-circuits on a revision match — could never be
healed by re-dispatching that revision. Only a later, different revision
recovered it.
Now a null blob fails the apply: the revision is left where it was,
NodeDeploymentState records Failed with the reason, and the coordinator gets a
Failed ACK. Leaving the revision alone is what makes the retry actually land
instead of being waved through.
This is about telling the truth, not about tearing anything down — the node
keeps serving its last-known-good address space, drivers and subscriptions
throughout (#485).
Tests, RED-first (both verified failing with "should be Failed but was
Applied"): the ACK/revision assertion, plus the one that matters — after a
failed apply, re-dispatching the SAME revision now genuinely applies. Its
recovered artifact adds a second driver precisely so a short-circuited ACK
(which has no side effects) cannot satisfy it.
Four existing tests changed, and both changes are deliberate:
- DriverHostActorTests.SeedDeployment never set ArtifactBlob at all. Its three
consumers are about the apply/ACK/state machine, not the artifact, and now
need a genuine apply — so the helper seeds a well-formed artifact declaring
no drivers. That is what the composer emits for an empty configuration, and
is precisely what "bytes we could not read" is NOT.
- EmptyArtifact_IsNotCached asserted "the apply still succeeds — an empty
artifact is a legitimate no-op deployment". That premise is the bug. Flipped
to Failed; the test's actual subject (nothing is cached) is untouched and now
holds for two independent reasons.
Closes#486
Claude-Session: https://claude.ai/code/session_01GASWkNEi68FSCtvr6rLoEW
New Props/ctor parameter appended LAST at all three positions - the forwarding
list inside Props.Create is positional and compiles into an expression tree, so a
mis-ordered argument is usually type-compatible and binds the wrong dependency at
runtime. All 26 existing test construction sites use named arguments and needed no
change.
ReconcileDrivers now returns the blob it loaded. It catches its own DB failures and
returns without rethrowing, so ApplyAndAck can reach its success path having spawned
zero drivers; caching on 'the apply succeeded' would persist an empty artifact as
last-known-good and boot the node into an empty address space during the next
outage. Verified: weakening the guard to null-only turns EmptyArtifact_IsNotCached
red.
The store runs in its own try/catch because an Applied ACK has already been sent by
then - an escaping exception would land in ApplyAndAck's catch and emit a second,
contradictory Failed ACK for a deployment the fleet believes is live.
Joseph Doherty