Two gaps the Task 23/24 review found, both blocking Task 26's live gate.
Gap 1 — browse-commit produced a silently dead MQTT tag. RawBrowseCommitMapper
had no `Mqtt` case, so a committed leaf fell through to the generic
`{"address": …}` key. Neither MqttTagDefinitionFactory entry point reads
`address`: the tag deployed clean and reported BadNodeIdUnknown forever, with
no signal at commit time. Predates Task 23 (Plain was affected too), but Task 23
built the Sparkplug metric tree precisely so an operator could browse and commit
a binding.
The address is a DESCRIPTOR, not a reference string, and it cannot be recovered
from the browse node id: `{group}/{node}[/{device}]::{metric}` where a metric
name legitimately contains `/` (`Node Control/Rebirth`) — the ambiguity
MetricSeparator's remarks already name. So the session STATES it, via a new
`AttributeInfo.AddressFields` seam, and the mapper reads it. Which keys are
emitted is also how the mapper learns Plain vs Sparkplug — the driver type
reaching it is just `Mqtt`, and the mode lives on the driver config. Key names
are single-sourced in the new `MqttTagConfigKeys` (producer, mapper, factory),
with the literals pinned by a test so a symmetric rename cannot silently unbind
already-persisted blobs. A leaf with no stated address is refused at commit in
words rather than committed dead.
Gap 2 — RequestRebirthAsync had no UI. Task 23 shipped it backend-only; Task 26
step 1 assumes the button, and Task 25's runbook notes the picker tree stays
empty until a birth lands, so it is the only way to fill it on demand. Added to
the /raw browse modal: scope = the clicked tree node (device/metric resolve up to
their edge node, group fans out and is refused whole past 32), an explicit
two-click confirm naming the resolved scope and its consequence, the outcome or
the refusal shown rather than swallowed. Offered only for a Sparkplug session
(new `IRebirthCapableBrowseSession.RebirthAvailable` — one session class serves
both modes, so a type test alone would draw a button that can only throw) and
only to a DriverOperator; the server-side gate remains the boundary.
Tests: MQTT 545 → 581, AdminUI 781 → 800. The round-trip tests feed the emitted
blob to the REAL factory and were falsified by mutating the emitted key name.
Claude-Session: https://claude.ai/code/session_01GASWkNEi68FSCtvr6rLoEW
Unseals the Sparkplug branch of the MQTT address-picker browser that Task 10
deliberately sealed shut, and adds the first (and only) sanctioned publish on a
browse session.
- MqttBrowseSession serves Group -> EdgeNode -> [Device] -> Metric in Sparkplug
mode, decoded from observed NBIRTH/DBIRTH certificates (the only Sparkplug
messages that name their metrics). Node-level metrics hang directly under
their edge node -- no synthesised device folder, because the authored address
tuple genuinely has deviceId = null for them. Metric node ids use a '::'
separator: a metric name may contain '/', so slash-joining would make a
node-level metric indistinguishable from a device folder.
- AttributesAsync is purely birth-derived in Sparkplug mode. The plain path's
UTF-8 inference / payload-snippet machinery does not run and no payload bytes
are retained: a Sparkplug body is protobuf and would be reported as
"(N bytes, binary)" for every metric in the plant. A datatype ToDriverDataType
cannot map is reported as the Sparkplug type name, never coerced.
- RequestRebirthAsync(scope) is the one publishing member, reached only by an
explicit operator action. It routes through the counted PublishAsync
chokepoint via a private RebirthTransport adapter, so PublishCountForTest
still proves that OpenAsync/RootAsync/ExpandAsync/AttributesAsync/Observe/
DisposeAsync publish nothing -- now in both modes. A device or metric scope
resolves up to its owning edge node (NCMD is node-addressed); group scope
enumerates observed edge nodes and is refused whole past
MaxGroupRebirthNodes = 32.
- BrowserSessionService.RequestRebirthAsync gates on the same DriverOperator
policy that gates the picker, evaluated server-side where the action happens
rather than only at render time, fails closed, and Info-logs the scope and the
published count. Exposed through the new IRebirthCapableBrowseSession contract
so "does this session write?" stays a type question.
- ToBrowseOptions' Last-Will landmine re-verified: MqttDriverOptions still
carries nothing will-shaped (an NDEATH is a broker-published will and would be
invisible to PublishCountForTest), now pinned by a reflection guard.
Falsifiability: injecting a publish into RootAsync reddens the Sparkplug and
plain passivity tests; double-publishing per target reddens all four
one-NCMD-per-node assertions. 572/572 MQTT tests, 24/24 AdminUI browsing tests.
Claude-Session: https://claude.ai/code/session_01GASWkNEi68FSCtvr6rLoEW
Three review findings, all "unbounded work/memory from untrusted broker input"
rather than correctness bugs - but this points at a live plant broker.
1. InferPayload decoded the WHOLE payload on MQTTnet's dispatcher thread before
trimming to 64 chars. The node cap never engages here: a multi-MB blob on an
already-known topic creates no node, it just updates one, so the cost repeats
per message forever. Now at most PayloadInspectMaxBytes (512) are examined.
A blind slice can cut a multi-byte sequence, which the strict decoder would
report as "binary" - TrimToUtf8Boundary backs the window off to the last whole
sequence so good UTF-8 is never mislabelled. A clipped payload is String by
construction rather than inferred from a partial view.
2. The node cap bounded COUNT, not bytes. MQTT topics run to ~65KB, so 50k nodes
near that ceiling is a multi-GB tree. Topics now bounded at 1024 chars and
segments at 256, rejected whole (a truncated topic is a DIFFERENT topic the
picker would commit as a tag address) and surfaced via an __oversized__ marker
kept distinct from __truncated__ - the operator's remedy differs.
3. Control characters in a snippet would break the picker's single-line row;
Trim() only strips the ends. Now scrubbed to spaces.
Each guard was falsified independently by neutering it and confirming exactly one
test reddens. That found a real gap: the oversized-topic test was passing via the
SEGMENT bound, leaving the whole-topic bound untested - the test now uses many
short segments so only the topic bound can reject it.
Also records the .Driver project reference as a known, deliberate exception to the
.Browser -> .Contracts pattern, with its cost (AdminUI gains Core + Polly + Serilog)
and the clean fix (a leaf transport project; NOT a move into .Contracts, which is
deliberately transport-free).
Claude-Session: https://claude.ai/code/session_01GASWkNEi68FSCtvr6rLoEW
MQTT has no discovery protocol, so the AdminUI address picker learns the topic
space the only way there is: subscribe to the wildcard and accumulate what
arrives. MqttBrowseSession serves that observation as a segment tree (split on
'/'); MqttDriverBrowser opens it with a distinct "{clientId}-browse-{guid8}"
identity under a 5-30 s clamped budget.
Browsing publishes NOTHING - the load-bearing safety property, since the picker
runs against a live plant broker. Every outbound message must route through the
single PublishAsync seam that counts into PublishCountForTest; P2's operator-
triggered Sparkplug rebirth is the one intended exception. Sparkplug mode fails
fast rather than serving a raw spBv1.0 topic tree that looks like a metric tree.
Deviation from the plan's ref list: the project also references .Driver so the
browse CONNECT reuses MqttConnection.BuildClientOptions (TLS posture, CA-pin
chain validator, credentials). A second copy would be a security divergence.
Claude-Session: https://claude.ai/code/session_01GASWkNEi68FSCtvr6rLoEW
Joseph Doherty