2 Commits

Author SHA1 Message Date
Marc Schier 466c5cb982 Robot intent follow-ups: multi-controller executors, spec fixes, and an MCP tool library (#4195)
Follow-ups to #4165, plus the work that followed from re-checking this
branch against the specification. Everything started as a defect found
by review or by probing the running code; the specification is unchanged
except where noted.

The TLS certificate lifetime fix (#4196) and the OpenUSD work (#4198)
were both merged into this branch. #4196 has since landed on master, so
it no longer appears in this diff. #4198 was closed in favour of this PR
and its content is here.

The MCP trim/AOT work (#4228), the `DataGenerator` null `NodeId` fix
(#4227) and the NodeSet external-parent import fix (#4229) have since
been merged in as well. All three are closed in favour of this PR and
their content is here, described under *Making the MCP libraries trim
and AOT clean*, *A generator that returned the value you opted out of*
and *A NodeSet parent that lived outside the import batch* below.

## A two-arm cell could not be built

`IntentExecution` carried no controller identity, and there was
effectively one `IIntentExecutor` per server. An executor handed an
execution therefore could not tell **which arm** it was for, so a cell
with two `IntentControllerType` instances — an ordinary configuration —
was not expressible through the builder or DI.

Both halves are addressed:

- `IntentExecution` now carries `ControllerId` (`NodeId`, the OPC UA
identity) and `ControllerName`, so one shared executor can discriminate;
- DI gained per-controller registration —
`AddRobotIntentExecutor<TExecutor>(controllerBrowseName)` and an
instance overload — so two genuinely different executors can coexist.

Resolution order is `WithExecutor` → per-controller DI registration →
the single DI executor → a build-time throw. There is still **no silent
fallback** to a rejecting executor; that was a Critical defect fixed in
#4165 and it stays fixed. `IIntentExecutor` is unchanged, so this is
purely additive.

## Declarations that were quietly untrue

- **`Accepts<T>` silently discarded a redeclaration.** Declaring an
intent type twice — say to narrow `cancelSupported` on the second call —
kept the first, wider declaration and said nothing. That is the same
class of defect as the capability-honesty problems #4165 fixed
(`PauseSupported` declaring a pause the host could not perform;
`Aborting` degrading silently to `Buffered`). Identical redeclarations
remain idempotent; conflicting ones now throw `BadInvalidArgument`.
- **`RI-Interop-40010` assumed Annex B item 3 rather than checking it.**
It now requires exact set equality between the OPC 40010
`TaskProgramName` values and the Robot Intent `ProgramType.ProgramId`
values. Both sides are readable from the address space without
commanding the robot, which is what makes the requirement structural
under §12.1.

## Two things the specification requires that this did not do

Re-checking the implementation against the merged draft revision turned
up two genuine violations. Both are fixed, and the NodeSet is untouched
by either.

- **Every graphed mission reported `Failed` on success.**
`MissionRules.SelectTransition` returned `null` for two different
situations — a graph *terminus*, which is the normal success path, and a
branch point whose conditions all evaluated false — and the caller
collapsed both into `Failed`/`NoTransition`. A three-way result
(`Terminus` / `Selected` / `NoConditionMatched`) separates them, so a
mission that runs to its end now completes. The failure reason surfaces
through the inherited Part 10 result container rather than a new member.
- **Facet URIs were never published.** An upstream `may` became a
`shall` in the revision this branch adopts.
`RobotIntentConformanceUris.Facets` held 31 URIs with **zero**
production references — the set existed but nothing emitted it. The
published set is now derived from `RobotIntentFacetCalculator`, the same
authority that already computed `SupportedFacets`, rather than from a
second hand-maintained list that could drift; a reflection test pins the
two together.

## An easy client mistake

`RequestAuthorityAsync` returns a lease the caller must remember to
inspect. Forgetting makes every later submission fail with
`ControlNotOwned` for reasons that are invisible at the call site.
`RequireAuthorityAsync` throws instead, and names the current owner.
`RequestAuthorityAsync` is untouched — inspecting and branching is
legitimate.

## Letting an agent drive the robot

New `tools/Opc.Ua.Mcp.Robotics` gives a language model the intent API as
MCP tools: 36 across discovery, monitoring, direct control and missions,
behind a `Robotics` tool profile, composable into any MCP host exactly
as the existing OPC UA tool packages are. The `IntentViewerClient`
sample hosts them behind `--mcp` (stdio by default, HTTP when `--view`,
since MCP stdio and the in-process viewer would otherwise share stdout),
and the sample gained a pallet scene so an agent can pick and stack
parts and watch the result in the OpenUSD viewer. All the scene logic is
server-side — no viewer or connector changes.

Four gaps in the client API had to be filled first, since the tools are
a thin layer over it and could not have been written honestly without
them: `ReadStateAsync`, `ListOperationsAsync`/`ListMissionsAsync`,
controller-level
`CancelIntent`/`CancelAll`/`Pause`/`Resume`/`Retry`/`ReleaseControl`,
and `WaitForCompletionAsync`.

The tools refuse rather than paper over: a refusal from the server is
returned with its `IntentFailureEnum` and never retried, and command
authority is never acquired as a side effect of a tool call.

**One defect this surfaced:** `--profile robotics` shipped 36 tools that
could not do anything. Every robotics tool resolves a named OPC UA
session and only the connection tools can open one, so with no `Connect`
in the catalogue the whole profile failed. A test had pinned the defect
in place, asserting the profile did *not* contain `Connect` on the line
below the `diagnostics` assertion requiring it. Each package now
declares its own requirement in its registration extension rather than
the host special-casing it, so an application embedding
`Opc.Ua.Mcp.Robotics` directly gets a usable catalogue without
reproducing the host's pairing. `Full` still takes the connection tools
from the core package, so they are never registered twice. The
replacement test states the invariant — a profile exposing
session-scoped tools must expose the tools that open a session — rather
than the instance.

## Making the MCP libraries trim and AOT clean

*Merged from #4228.*

`Opc.Ua.Mcp.Core` is now `IsAotCompatible` on `net10.0`, and the
reflection the analysers then reported is gone. Turning the analysers on
is the point: until now they were not running on these libraries at all
— including on the tool library this branch adds.

- **`OpcUaJsonHelper.Serialize`** went through `JsonSerializer` (IL2026
/ IL3050). The conversion helpers in that class already reduce every OPC
UA value to a closed set — `null`, the primitive scalars, `string`,
`Dictionary<string, object?>` and lists thereof — so the JSON is now
written directly with a `Utf8JsonWriter`.

Output is unchanged, and that is asserted rather than assumed:
`OpcUaJsonHelperTests.SerializeMatchesTheReflectionBasedSerializer`
compares the new writer byte for byte against `JsonSerializer` for every
shape the helpers emit, including all numeric widths, the
custom-formatted scalars, nested sequences and strings that force the
encoder to escape.

One deliberate contract change: arbitrary object graphs are no longer
accepted. Serializing them needs reflection, so `Serialize` now throws
`NotSupportedException` naming the type instead of silently stringifying
it. No call site in the repository passes anything outside the closed
set.

- **`McpSchemaFilters`** used `JsonSerializer.SerializeToElement` on a
`JsonObject`; it now parses the node's own text, which needs no
reflection.

`Opc.Ua.Mcp.Diagnostics` is deliberately **not** marked. It depends on
SharpPcap and on the reflective service-call dissection in
`Opc.Ua.Core.Diagnostics`, neither of which is trim safe — which is why
that package does not opt in either. Two improvements are kept
regardless: `PacketDecodeTools` serializes `DecodedServiceCall` through
a source-generated `JsonSerializerContext`, and
`PacketCaptureTools.ListInterfaces` now carries the
`RequiresUnreferencedCode` / `RequiresDynamicCode` annotations that
`NetworkInterfaceEnumerator.ListLocalInterfaces` already declares, so
the constraint is visible to callers instead of implicit. Nothing is
suppressed.

Marking an assembly `IsAotCompatible` only proves its own IL is clean;
it says nothing about whether the library still functions once
reflection is gone. So `Opc.Ua.Aot.Tests` references `Opc.Ua.Mcp.Core`
and exercises it with JSON reflection disabled, stating what is and is
not true today:

- tool **results** serialize without reflection — this would fail
outright if the `Utf8JsonWriter` change regressed;
- tool **registration** still requires reflection, because the MCP SDK
builds each tool's input schema by asking `JsonSchemaExporter` for a
`JsonTypeInfo` of every parameter type. Without a source-generated
context covering the tool signatures — and with the injected
`OpcUaSessionManager` being described rather than treated as a service —
that throws `NotSupportedException`.

The second test asserts the throw. It documents the remaining gap and
turns red the moment someone closes it, rather than leaving it to be
found in a published binary. The package README says the same thing in
prose.

**Two pre-existing issues this surfaced, both outside this PR:** pulling
`Opc.Ua.Mcp.Diagnostics` into an AOT publish reports `IL2046` / `IL3051`
on `NicCaptureSource.StartAsync`, which is annotated
`RequiresUnreferencedCode` / `RequiresDynamicCode` while the
`ICaptureSource.StartAsync` it implements is not, and `IL2075` on
`ServiceCallReassembler.GetCollectionCount` / `GetPropertyString`, which
call `Type.GetProperty` on the result of `GetType()`. Happy to file
these separately if useful.

## A generator that returned the value you opted out of

*Merged from #4227. Fixes #4226.*

`GetRandomNodeId(useBoundaryValues: false)` could still return
`NodeId.Null` — one of the boundary values the same method offers when
boundary values *are* requested. A caller that opted out should not
receive one, and `GetRandomExpandedNodeId` builds on it and inherited
the same behaviour.

The `IdType.Opaque` branch is the practical path:
`GetRandomByteString()` draws its length with
`NextInt32(MaxStringLength)`, which is inclusive of zero, and a
zero-length opaque identifier in namespace 0 satisfies `NodeId.IsNull`.
With three namespaces and `MaxStringLength` at 10 that is roughly **one
call in 130**. A numeric identifier of `0` in namespace 0 is null too,
at around one in four billion.

The draw is now repeated while the result is null and boundary values
were not requested. Guarding the result rather than the individual
branches covers every identifier type, including the numeric case,
rather than only the one that happens to be reachable today. The
`useBoundaryValues: true` path is untouched, so boundary values remain
available when they are asked for.

Four tests in `tests/Opc.Ua.Core.Tests/Types/DataGeneratorTests.cs` loop
20,000 draws, because at one call in 130 a single draw proves nothing.
Against the **unmodified** generator they fail on draw 93 and draw 1346.
Two of the four exist to keep the fix honest rather than to test the
bug: `GetRandomNodeIdStillProducesEveryIdentifierType` catches a "fix"
that simply stopped emitting opaque identifiers, which would satisfy the
null assertions while silently narrowing the generator, and
`GetRandomNodeIdWithBoundaryValuesStillYieldsThem` confirms the leak was
closed rather than the feature removed.

**How it was found:** an intermittent downstream test failure. A test
server initialising a static `NodeId`-valued variable via
`TestDataSystem.ReadValue` occasionally stored `NodeId.Null`; the
encoder correctly writes that as JSON `null`, and a consumer asserting a
value was present failed about one run in five — never reproducibly in
isolation. It only surfaced under load because `UnsecureRandom.Shared`
is a fixed-seed, process-global generator shared between `DataGenerator`
and OPC UA transport jitter, so the number of draws preceding
address-space initialisation depends on what else is running in the
process.

## A NodeSet parent that lived outside the import batch

*Merged from #4229.*

`UANodeSetHelpers.LinkParentChildRelationships` builds its lookup table
from **only the nodes in the current import batch**, links a child when
the parent is found — and then cleared `instance.Handle`
**unconditionally**, which is exactly where `Import` had stashed the
authored `ParentNodeId`. A node whose parent lives in another NodeSet,
or is owned by another NodeManager, therefore lost that parent
**silently** at import, and nothing downstream could recover it.
`RuntimeNodeSetNodeManager.CreateAddressSpaceAsync` already has a step
that wires references to external node managers; the parent link never
reached it.

Such a parent is now recorded rather than discarded, and exposed through
`UANodeSet.TryGetUnresolvedParentNodeId`. A parent that resolved
normally inside the batch is **not** recorded, so a caller does not
re-wire references that already exist. The record lives in a
`ConditionalWeakTable`, so it does not keep an imported node alive and
does not widen `NodeState` — whose `Handle` is a general-purpose slot a
caller may legitimately use for its own purposes, and so is not a safe
place to leave the value.

`RuntimeNodeSetNodeManager` consumes it to report the one case that
cannot be repaired automatically. In NodeSet2 the `ParentNodeId`
attribute is a *hint*; the authoritative edge is the entry under
`<References>`, which the reverse-reference pass already turns into an
external reference. A node that names an out-of-manager parent but
carries **no such Reference** materializes with no path from that
parent, and no ReferenceType can be inferred to synthesise one — so it
is reported as an authoring defect rather than guessed at or silently
accepted.

This is deliberately **not** a fix for a specific address-space symptom.
It removes a silent loss of authored information and gives callers the
means to act on it. Whether any particular orphaned-node report is
caused by this path, or by namespace-index translation elsewhere, still
needs separate diagnosis.

**Changed while merging.** As authored in #4229 the accessor was
`GetUnresolvedParentNodeId`, returning `NodeId?`. `NodeId` is a readonly
struct implementing `INullable`, so that was a `System.Nullable<NodeId>`
wrapped around a type that already carries its own null representation —
which this repository excludes in favour of an `IsNull` check, and it
asks for `TryGet` over casting on struct types. The tests
correspondingly asserted `Is.Null` against a struct, which the testing
rules also exclude. It is now `bool
TryGetUnresolvedParentNodeId(NodeState, out NodeId)`, yielding
`NodeId.Null` when there is no unresolved parent. The API is unshipped —
it arrives with this branch — so nothing depended on the previous shape.
Both tests were re-verified by mutation after the rewrite: disabling the
record in `LinkParentChildRelationships` still fails
`ImportKeepsAParentThatIsNotInTheSameBatch`.

## Dependencies

- **OpenUSD to `0.7.0-alpha`.** All 11 issues we filed upstream are
fixed, so the workarounds they justified are gone and the parts of the
pump and generator samples that were blocked on them are implemented.
- **ModelContextProtocol to `2.1.0`** across all five MCP tool libraries
and the executable. No code changes were needed — the surface we use is
unchanged in 2.x — but central package management required a cascade of
pins, each commented where it sits. Both transports were verified
against a running server rather than assumed. MCP 2.x is stateless (no
`initialize`, no `Mcp-Session-Id`); an OPC UA session is application
state addressed by a caller-supplied name, which fits that model but
does assume process affinity, and that assumption is now written down
rather than implied.

## Infrastructure

The `code coverage` gate was measuring nothing on this branch and
reporting success. It is fixed and now enforced, which immediately
exposed real gaps — most usefully `RoboticsIntentJson`, which parses
agent-supplied JSON (untrusted input from a language model) and had no
tests at all. It is now at full line coverage in CI. Patch coverage is
**90.20%** against a 75% floor.

The `netstandard2.1` build leg was also failing. The MCP projects build
as empty shells under a legacy `CustomTestTarget`, and the viewer sample
referenced them on the target framework alone, so it tried to resolve a
net10.0 shell from net8.0. The sample now derives MCP support from
whether those projects are actually being built.

## From review

A review pass over the branch found two real defects, both fixed.
`RoboticsIntentJson` parses JSON written by a language model, so every
malformed shape it can be handed is reachable input; it indexed pose
arrays without checking their length and enumerated properties without
checking their kind, so a short or wrongly-typed array escaped as
`IndexOutOfRangeException` or `InvalidOperationException` rather than
the argument error the tool descriptions promise the agent. Separately,
`IntentOperationHandle` treated a zero `QueuePosition` as "not observed"
and discarded it, so a handle kept reporting the last queued position
after the server had said the operation left the queue.

The pose validation immediately caught a latent test defect: the pallet
scenario interpolated doubles into JSON with the current culture, so
under a comma-decimal culture `[0.12, 0.16, 0.28]` became a six-element
array. It passed only because that submission is expected to be refused
for want of authority, so the wrong coordinates were never used.

A third review finding — that a default-constructed
`RobotIntentControllerState` hands out a null `NodeId` — was checked and
rejected: `NodeId`, `QualifiedName` and `LocalizedText` are readonly
structs here, so `default` is the null value and `IsNull` is `true`. The
tests asserting that invariant are kept.

A second review pass over the merged branch found two more, both fixed
and both about an error surfacing as the wrong kind of failure rather
than about a wrong result:

- **Malformed agent JSON did not arrive as an argument error.**
`RoboticsIntentJson` turns every *validation* failure into an
`ArgumentException` — a wrong root kind, a missing property, a short
pose array — but three `JsonDocument.Parse` calls and the NodeId parse
were unguarded. A syntax error escaped as `JsonException` and an
unparseable NodeId as `ServiceResultException`, which are the two shapes
a language model is most likely to produce. That is the same defect
class as the pose/kind checking above: a caller separating bad input
from a genuine fault had to know to catch three unrelated exception
types. Parsing now goes through one helper that reports a syntax error
as an `ArgumentException` naming the argument, keeping the
`JsonException` as the inner exception so the position is not lost, and
the NodeId goes through `NodeId.TryParse` rather than `Parse`,
collapsing its two failure modes into one.
`MalformedIntentJsonIsRejected` had asserted
`InstanceOf<JsonException>`, pinning the behaviour rather than the
intended contract; it now asserts `ArgumentException` like every
neighbouring test, and three tests cover the newly guarded paths.
- **`ConditionalWeakTable.Add` throws on a duplicate key.** Not
reachable today, but `TryGetUnresolvedParentNodeId` documents `Handle`
as a general-purpose slot a caller may use for its own purposes — and a
caller doing exactly that before re-importing into the same collection
would take a hard throw from inside the import pipeline. Removing first
makes the most recent import win. `AddOrUpdate` would say this more
directly but does not exist on `netstandard2.0`.

## Deliberately not fixed here

`FastenIntentDataType.Joint` is refused when the Server exposes no OPC
40450/40451 model, and a client cannot discover that before calling.
That is **not fixable in this repository**: §5.4.2 makes `Joint` the
defining mechanism while §11.3 says the parameters otherwise stand
alone, and `IntentCapabilityDataType` declares capabilities at
intent-type granularity with no member-level mechanism anywhere in the
model. It is a specification gap, raised as S4 on
[marcschier/opcua-drafts#60](https://github.com/marcschier/opcua-drafts/pull/60)
rather than worked around with a bespoke mechanism the spec does not
define.

## Validation

`dotnet build UA.slnx -c Release` on the merged branch — **0 errors, 0
warnings**, with the AOT analysers now running over `Opc.Ua.Mcp.Core`.

| Suite (net10.0) | Tests |
|---|---|
| `Opc.Ua.Core.Tests` | 4247 (86 skipped) |
| `Opc.Ua.Robotics.Tests` | 540 |
| `Opc.Ua.OpenUsd.Tests` | 909 |
| `Opc.Ua.Tools.Tests` | 419 |
| `Opc.Ua.Server.Tests` — `RuntimeNodeSet` | 94 |
| `Opc.Ua.Robotics.Intent.Tests` | 22 |
| `Opc.Ua.Aot.Tests` — `McpAotTests` | 3 |

0 failures. `Opc.Ua.Tools.Tests` rose from 409 to 419 with the
serializer-equivalence tests from #4228 and the malformed-JSON tests
from the second review pass, and `Opc.Ua.Core.Tests` covers the
`DataGenerator` tests from #4227 and the import tests from #4229.
`UANodeSetHelpers` also passes on **net48** (5/5). The MCP
agent-usability grader scores Core 100 / Full 100.

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
Copilot-Session: a248a589-9a20-4372-868e-5d347e57001b
Copilot-Session: 9e6a5abf-3299-4cd1-9855-010fedbf0ad8
Copilot-Session: a0718e8a-a158-45c5-929d-e1d6c0982431
2026-08-11 13:03:36 +02:00
Marc Schier 2b44fcad22 Robot intent: a task-level command API with a Part 10 lifecycle (#4165)
# Description

Implement the draft **OPC UA — Robot Intent** companion model end to
end: task-level motion verbs, a Part 10 lifecycle, a server hosting
surface, a client, two samples and a live integration suite. It replaces
the opt-in convention API merged in #4127 with an implementation
generated from a companion information model.

## Why

OPC 40010-1 *Robotics* describes robot **topology** in detail and
defines **no motion verbs at all** — its entire actuation surface is
`Start`, `Stop` and loading a named program. A conformant client can
discover everything about a robot's construction and cannot ask it to
move anywhere. #4127 filled that gap with ten verbs in an
application-owned namespace, resolved by BrowseName, and the file said
what it was: *"opt-in, explicitly non-normative industrial operation
conventions"*.

That contribution established a **vocabulary**. It established no
**lifecycle**, and the lifecycle is the harder half.

A motion takes seconds; a pick takes a minute. OPC 10000-4 §5.12.2
discards a method result when the Session ends *"independent of the task
actually performed at the Server"* — so a synchronous motion method does
not merely time out, it **loses the outcome of work that has already
physically happened**. OPC 10000-10 §4.1 gives the OPC Foundation's own
resolution: a Method performs a calculation, a **Program** runs a batch
process or a machine tool part program.

So `SubmitIntent` returns as soon as the intent is *admitted*, and what
it returns is a NodeId — an `IntentOperationState` (a Part 10 program
instance) the client subscribes to for progress and reads for the
result.

## What changed

**Model and shared code** — `Opc.Ua.RobotIntent.NodeSet2.xml` is
source-generated in `Opc.Ua.Robotics`, so the enums, the polymorphic
intent structures, `IntentOperationState : ProgramStateMachineState`,
the method states and the typed clients derive from the model rather
than being hand-written. Its only `RequiredModel` is the base UA
namespace, so a server can adopt it without OPC 40010 or DI. `PoseMath`
implements the specification's Annex C conversion between its unit
quaternion and the core `ThreeDFrame` — including the `asin` clamp that
stops a pole orientation becoming a domain error, and the
non-negative-`w` representative that makes two servers agree on four
numbers. `FrameTree` composes transforms along the frame tree.

**Verbs are a DataType hierarchy, not one Method each.** A single
submission and a mission step are then the same shape, and a new intent
is a subtype rather than a new method — which is what
`AddOperation<TRequest,TResponse>` was working around.

**Server** — `IntentControllerHost` owns admission in the
specification's order, the queue with PLCopen buffer modes, blending,
cancellation *with the server's right to refuse*, missions with a
committed base and a revisable horizon plus an IEC 61131-3 step graph,
safety-aware refusals, real-time channel brokerage, and the capability
declaration. All thirteen Methods are wired; command authority and
channel leases are released when the holding Session closes; every
client-supplied NodeId is validated against the controller being
commanded (clause 11.3). `RobotIntentNodeManager`, the fluent
`IIntentControllerBuilder` and `AddRobotIntent`/`ConfigureRobotIntent`
make it reachable, and `RobotIntentFacetCalculator` computes which of
the specification's facets an instance actually satisfies.

**Client** — `RobotIntentClient` discovers
`Server/RobotIntent/Controllers` and reads what a robot accepts;
`IntentOperationHandle` subscribes and completes on a terminal state,
recovering the result after a reconnect because clause 6.7 promises it
survives; `CommandAuthorityLease` and `RealTimeChannelLease` manage the
two exclusive resources; fluent builders cover every intent and mission.

**Samples** — all robotics samples move under `samples/Robotics/`.
`IntentEnabledRobot` is one UR5e-style offset-wrist arm on a bench,
declared completely enough to show what a conformant server publishes,
with a simulated safety source so the clause 10.4 refusals are
demonstrable. `IntentViewerClient` turns a **click on a target prim in
the OpenUSD viewport** into an intent and watches the arm execute it; it
also runs headless, which is how CI exercises it.

**Intents execute serially**, which satisfies every `BlockingMode`
constraint by construction: the specification forbids beginning a
`Single` or `Hard` intent while another executes and merely *permits*
`None` and `Soft` to overlap.

The convention API (`RoboticsOperationConventions`,
`RoboticsOperationsBuilders`, `RoboticsOperationsClient`) is removed.

### On safety — what this deliberately does *not* claim

The interface is **non-safety-rated**, and that is a property of the
technology rather than a scoping choice. OPC 10000-15 carries cyclic
safety data from a SafetyProvider to a SafetyConsumer; the consumer's
`RequestSPDU` holds an identifier, a monitoring number and one octet of
explicitly **non-safety** flags, so a caller has no channel through
which to supply safety-rated arguments. Every safety fieldbus
(PROFIsafe, CIP Safety, FSoE, openSAFETY) expresses a safety command as
a **continuously asserted cyclic signal**, because the integrity
argument rests on the fail-safe state that follows when assertion
*stops* — and a Method call has no defined behaviour when it stops being
called.

What the host does instead is **observe and refuse**:
`UpdateSafetyState` is how the application reports what the safety
system is enforcing, and admission then refuses on the same values a
client can read, so a refusal is explainable from the address space
rather than from Server-internal state. It may never *instruct* the
safety system, and no Method here commands a safe motion function,
changes an operational mode or clears a stop.

## Defects this found in the specification, fixed upstream

Implementing a specification is the only way to find out whether it can
be implemented. Seven defects went back to
[marcschier/opcua-drafts#47](https://github.com/marcschier/opcua-drafts/pull/47)
rather than being worked around here:

- **Refusal was unobservable.** Clause 6.2 orders six distinct refusals
and clause 5.8 calls the failure set "small and diagnosable on purpose"
— but `SubmitIntent` returned only `IntentId` and `Operation`, so a
client could see *that* something was refused and never *which*. It now
returns `Accepted`, `Failure` and `Message`, and clause 6.2 states that
a refusal returns `Good` rather than substituting a Bad `StatusCode`.
- **The Part 10 promotion was illegal.**
`IntentOperationType.ProgramDiagnostic` was declared as a Property of
`PropertyType`; OPC 10000-10 declares it a Variable of
`ProgramDiagnostic2Type` reached by `HasComponent`. The declaration
added a *second* member beside the inherited one instead of promoting it
— which is precisely why an earlier version of this branch had deleted
it. Correcting the TypeDefinition made it generate cleanly with **no
change to the curated Core**.
- **Clause 9 said nothing about the Method surface.** A server could
declare `MissionsSupported` true and omit `SubmitMission` entirely,
because the mission and channel Methods are Optional. This
implementation did exactly that until an integration test caught it. A
fourth honesty rule and a table now fix which Methods each declaration
implies.
- **Conformance was not machine-readable, and two implementations
disagreed.** Clause 12 defined conformance in terms of facets and gave a
Server nowhere to publish which ones it satisfied, so every client had
to re-derive Table 12.2 from the address space. This repository proved
why that fails: the server''s `RobotIntentFacetCalculator` and the
client''s `RobotIntentRules.DeriveFacets` each implemented clause 12.2
independently and **disagreed on essentially every row** — the client''s
`Blending` was `BlendingSupported` alone where the server also requires
all four blending buffer modes, its `QueuedIntents` was `MaxQueueDepth >
0` where the server also requires `Buffered`. A client and server from
the same release answered "does this controller conform?" differently,
and both were reading the specification correctly, because several rows
are behavioural and no amount of browsing settles them.
`IntentCapabilitiesType` now carries **`SupportedFacets`**, exactly as
OPC 10000-5 does with `ServerCapabilitiesType.ServerProfileArray`,
RI-Base requires it, and clause 12.2 separates structural requirements a
Server shall meet before listing a facet from attested ones governed by
clause 9.
- `WaitIntentDataType.Signal` was unbounded where clause 11.3 has to
check it; §11.3 gained a table fixing the expected type of every
NodeId-valued member; §5.7.0 gave `Ready`/`ActiveIntent`/`ActiveMission`
normative meaning; §6.9 bounded `RequestedLease`; §6.5 and §6.4 now say
what a server that cannot differentiate `StopMode` must do, and which
stop a superseded intent gets.

## Bugs the tests and reviews caught

Each of these would have been silent in the field:

- **The execution engine was never wired into the public API.**
`IntentControllerBuilder.RegisterAsync` built the address space and
never started an `IntentControllerHost`, so through the documented
`AddRobotIntent` → `ConfigureRobotIntent` path **every Method returned
`BadNotImplemented`** and the registered `IIntentExecutor` was never
resolved. A browsable address space is not a working robot interface,
and only a live integration test showed the difference.
- **NodeId scoping failed open on an empty index.** A controller
advertising `CallProgramIntentDataType` with no published `ProgramType`
accepted an *arbitrary* NodeId as `CallProgram.Program` — and
`CallProgram` runs code the server holds.
- **Blending completed the predecessor at submission time** and
abandoned its motion, telling the client it succeeded and publishing an
all-zero pose at the origin as a genuine `AchievedPose`.
- **Mission base immutability compared only identifiers**, so a client
could keep the ids and swap the *motion* of an already-committed step.
- **`FinalResultData/Result` was never registered** with the node
manager: Browse showed it, Read returned `BadNodeIdUnknown` — so clause
6.7's promise to a Part 10 client did not hold.
- `DisposeAsync` disposed primitives out from under in-flight executor
code; re-using a terminated `IntentId` destroyed the retained result and
duplicated a NodeId; neither side registered the Robot Intent
encodeables, so `Pose3DDataType` did not decode; host startup was hooked
to a task that ran in only one hosting shape.
- The result was published **after** the state went terminal;
capabilities were resolved against a stale namespace table; an empty
`ContentFilter` arrives as an empty element array rather than a null
filter, so testing only for null made every unconditional mission
transition silently untaken — a mission would run its first step and
stop.

### Found by a later test-quality audit, after the above was written

An audit of the test suite itself found five tests whose **names**
asserted a normative requirement while their **code** asserted something
weaker or nothing at all. The worst **fabricated the answer it
checked**: a helper caught a decode failure and invented "5 supported
intents, 6 axes, all facets true", so six capability-honesty assertions
across four tests could pass while reading nothing from the server. The
fallback is gone and the suite passes with honest reads.

Chasing the facet gaps it reported led to the clause 12 defect above.
Two further defects followed from completing that work:

- **`RI-Interop-40010` was never computed**, and the code documented the
omission as impossible to fix "because the calculator receives only a
Robot Intent controller, not the linked OPC 40010 model". That was
wrong: Annex B's structural requirement is an **inverse**
`HasIntentController` reference, reachable from `IntentControllerState`
— and the integration suite was already browsing exactly that. A server
implementing Annex B could not claim Annex B.
- **The published claim could go stale.** `SupportedFacets` was a
snapshot taken during `RegisterAsync`, so a reference attached
afterwards left it wrong. It is now bound through `BindRead` and
recomputed on read, so the claim tracks the address space by
construction rather than by discipline — which matters for anyone
bolting Robot Intent onto an existing OPC 40010 node manager, where the
attach ordering is often not theirs to choose.

Two tests that **could not fail** were also replaced: one asserted
`AccessLevel` equals `CurrentRead` to pin a read-only marking, but
`BaseVariableState` initialises every variable to exactly that, so
deleting the marking left it green; it is now a write expecting
`BadNotWritable`, including a real OPC UA `Write` service call over a
live session.

Finally, a build break that a plain build hides: `RoboticsAotTests` used
`out string?` in a project declaring `<Nullable>disable</Nullable>`.
Building the project **without** `-f` suppresses `CS8632` through
`NoWarn=nullable` and succeeds; building it **with** `-f net10.0`
resolves `NoWarn` differently, `CS8632` fires, and
`TreatWarningsAsErrors` makes it an error. CI builds per-TFM, so this
would have failed there while passing every local build to that point.

## Testing and coverage

| | |
|---|---|
| `dotnet build UA.slnx -t:Rebuild` | **0 errors, 2 warnings** — both
pre-existing `CA1861` in `tests/Opc.Ua.Tools.Tests`, a file this PR does
not touch |
| **Whole `UA.slnx` test suite, net10.0** | **50 of 52 assemblies fully
green** (measured at `40d9cf213`, before the `master` merge; the other
two are explained below) |
| `Opc.Ua.Robotics.Tests` | **467** net10.0, **447** net48 |
| `Opc.Ua.Robotics.Intent.Tests` (live client <-> server) | **20** on
net10.0 and net48, run repeatedly |
| `Opc.Ua.OpenUsd.Tests` | **904** after merging `master` (664 before;
the rest arrive with #4160 / #4162 / #4180) |
| `Opc.Ua.Aot.Tests` | **121/121** |
| `Opc.Ua.Di.Tests` (regression from the sample move) | **364/365**, one
pre-existing skip |
| **Changed-line coverage** | **90.7 %**, no file below 80 % —
comfortably above the enforced band, which after #4158 applies only to
patches larger than 100 changed lines |

The two non-green assemblies are **not** caused by this branch. Rather
than assert that, I ran the same selections at the merge-base
`ae241b662` on the same machine:

-
`ServiceCallReassemblerTests.PrivateRequestSummaryFormatsKnownRequestKinds`
expects `12.5` and gets `12,5` — a culture-sensitive assertion failing
on a European locale. Fails 4/4 on **both** commits.
-
`CertRotationLiveTests.L2Cert2RotateCertificateDuringServerRestartRecoversSharedChannelAsync`
fails on a teardown count. Fails 4/4 on **both** commits.
- A third failure seen once, AOT `FindServersAsync` with
`BadSecureChannelClosed`, did not reproduce: 4/4 on retest and 121/121
in the final run. Environmental.

Two things are worth calling out because they would otherwise be
invisible:

- `tools/**` is **not** in the `coverage-thresholds.json` ignore list,
and no test project referenced the OpenUSD tools assemblies — so their
changed lines counted as uncovered and the real patch figure was 75 %,
exactly the blocking threshold. Rather than widening the ignore list,
the pure decisions in the viewport host (pointer-to-physical-pixel
conversion, `RenderPickRequest` construction, stale-retry, backend
discovery, pick-mode selection) were separated from the Avalonia/native
shell and tested headless against a fake picking backend.
- `dotnet build UA.slnx` **hides warnings on unchanged projects**; only
`-t:Rebuild` surfaces them. That is how a `CA2263` introduced by a net48
portability fix survived several "zero warning" builds.

The multi-target requirement earned its keep repeatedly: it caught a
default interface implementation, `ArgumentNullException.ThrowIfNull`,
`string.Create` with an interpolated handler,
`ValueTask.FromResult`/`CompletedTask`, `Task.WaitAsync`, generic
`Enum.GetValues` and generic `Enum.IsDefined`, and a non-generic
`TaskCompletionSource` — none of which the net10.0 build complained
about. A net10.0-**only** hang in the simulated executor and two
load-sensitive flaky tests were also found and fixed at the cause.

### Merged with `master`

`master` (through `e73e71184`) is merged in as `08205d81d`. Four
conflicts, all where the two branches touched the same robot and OpenUSD
surfaces, and none resolved by dropping a side:

- #4162 added six files to `samples/MinimalRobotServer/` while this
branch moved that directory to `samples/Robotics/MinimalRobotServer/`.
They are kept at the moved path, and `UA.slnx` takes the union of both
sides' new projects.
- #4160 replaced `object` with a `UsdValue` union and rewrote `Flatten`;
this branch had reformatted the same method and fixed a path in its doc
comment. Git produced a hybrid that did not compile. The resolution
keeps `master`'s `UsdValue` arm and `Flatten(UsdValue)` overload in this
branch's block-bodied form, with the path fix retained.
- `master` inserted `FindStageCamera` directly before two methods this
branch had relocated, so the merge duplicated `WriteStageUsda` and
`GetPrivateStateRoot`. Only `FindStageCamera` is genuinely new —
`master`'s diff shows the other two as unmodified context — so the
duplicates are dropped and this branch's `internal` versions kept,
including the `GetPrivateStateRoot(string?)` overload the connector
tests use to stay out of the real user profile.
- `master` moved the OpenUSD stack to `0.4.0-alpha`; this branch pins
`OpenUsd.Rendering` in the test project so the renderer-pick tests can
reach the picking backend. Left at `0.1.0-alpha` that pin is below what
the viewer now resolves transitively, which is `CS1705`. The pin follows
`master`.

CI was green on `baaf35e9` with **190 checks passing and none failing**,
across every build leg (net472 / net48 / netstandard2.0 / netstandard2.1
/ net8.0 / net9.0 / net10.0, Debug and Release) and the full test matrix
on Windows and Linux. Since then `master` has been merged twice more and
two CI-stability fixes landed (see below), so the current head is
re-running. Locally, `dotnet build UA.slnx -t:Rebuild` gives **0
errors** and the 2 pre-existing `CA1861` warnings; Robotics **467**
net10.0 / **447** net48, Robot Intent **20** on both, OpenUSD **904**,
AOT **121/121**, source generation **3771**.

### Review round

Five reviewers over disjoint areas found defects worth calling out, all
fixed in `3ffec2c1`:

- **A refused mission step was reported `Succeeded`.** The advance path
returned the same `false` for "steps exhausted" and "step refused", so a
protective stop between steps told a supervisory system the mission had
completed while the robot stood halted with work unexecuted.
- **Three attacker-controlled NodeIds reached the executor unvalidated**
— `Pick.Tool`, `Place.Tool`, `ToolChange.DockStation`. `DockStation`
drives a physical tool-exchange motion to a location the server never
authorised. The replacement test enumerates NodeId members by reflection
so the next one added cannot be missed.
- **A lock-order inversion that loses a stop.** `CanCancel` and the
mission condition evaluator ran under the host lock while the executor's
own thread re-entered it via `ReportBlendBegin`.
- **A non-terminal executor outcome killed the pump** from outside the
`try/catch` that exists because the executor is untrusted — `Ready`
stayed true and submissions kept being accepted while nothing moved.
- **`Pause` published `Suspended` while the robot kept moving.** Now
queue-only and honest about it; the specification gained the matching
rule ([opcua-drafts
`357a558`](https://github.com/marcschier/opcua-drafts/pull/47)).
- **`RI-RealTimeChannel` and `RI-Safety` were false claims** — granted
on an empty folder with no methods, and on the mere presence of a
Mandatory node.
- **The Part 10 promotions never promoted.** Namespace-1 BrowseNames
declared second members beside the inherited ones; the conformance test
could not see it because its lookup stripped the prefix. Fixed upstream
and regenerated.
- **Renderer picking never worked.** The reflective probe bound a
renderer that is not a picking backend and throws off its owner thread.
It now binds only `IRenderPickingBackend`, falls back immediately and
loudly, and the docs say plainly that renderer picking is unavailable
with this package version.
- **The client lost command authority the instant it gained it** —
monitored items report the current value first, and the lease treated
every notification as a loss.

### CI stability fixes for master-side failures

The CI split in #4158 turned on legs that had never run, and two of the
failures they exposed were real bugs on `master` rather than anything
this branch introduced. Both are fixed here because they were blocking
every branch:

- **ECC key generation was broken on macOS.** `ExportExplicitParameters`
throws `PlatformNotSupportedException` there — Apple's
SecurityTransforms supports named curves only — and it was called for
exactly one value, the curve order `n`. The four curves OPC 10000-12
admits have published orders, so those are carried directly, with
`CurveOrderTableMatchesThePlatform` checking each against the platform's
own exported order wherever export works, so the constants cannot
silently drift. This accounts for the two ECC failures in
`test-macOS-latest-Server`.
- **The certificate-leak detector raced asynchronous disposal.** It
polled a fixed budget and reported whatever it saw, which cannot
distinguish a genuine leak (count steady) from a suite still draining
fire-and-forget disposals (count falling) — on a loaded agent that
produced `Certificate leak detected: 2 instance(s)` with every test
passing. It now waits for the count to **settle**, so a real leak is
reported sooner than before while a slow drain gets as long as it keeps
progressing. Shared by every suite that asserts no certificate leaks.

The remaining macOS failures on `master` (`Gds`, `Tools`,
`Redundancy.Samples`, `aot-macos`) have different root causes, are not
reproducible without a macOS host, and are **not** addressed here.

### Merged with `master` again

`master` through `416d619c4` (#4158, the CI matrix split and graduated
coverage bands) is merged in as `08ae4528`. One conflict, in
`docs/DeveloperGuide.md`, where both sides had deliberately rewritten
the coverage-gate section:

- `master`'s rewrite is kept in full — graduated `patch.bands`, Codecov
being informational-only, and where the numbers surface per CI system.
- This branch's paragraph about the `ignore` globs is kept too, re-sited
ahead of those subsections. I re-checked it against the merged
`coverage-thresholds.json` rather than assuming it still held: the list
is still `tests/**`, `samples/**`, `obj`, `bin`, `*.g.cs`, with
**`tools/**` absent** — so the warning that anything under `tools/` is
measured like product code, and that an assembly no test project
references contributes changed lines counted as *uncovered*, is still
accurate and worth keeping.
- `master`'s "reproduce a coverage failure locally" line supersedes this
branch's near-identical one, so only `master`'s survives.

Post-merge: `dotnet build UA.slnx -t:Rebuild` **0 errors**, 2
pre-existing `CA1861`; Robotics **467** net10.0 / **447** net48; Robot
Intent **20** on both.

### Getting CI green

The pipeline had never actually run on this branch until now (it was
waiting on the fork-PR approval gate), so the first run surfaced four
real problems, each fixed at source:

- **Seven build legs failed** because `IntentEnabledRobot` pins
`net10.0` for the OpenUSD payload but never opted into
`RestrictForLegacyTfm`. On the legacy legs the libraries build as
net472/net48, where `Opc.Ua.Types` exposes the `System.Threading.Lock`
polyfill publicly, and that collides with the sample's own net10.0 BCL
(`CS0433`). `Opc.Ua.OpenUsd.Connector.Viewer` was already using the
opt-out for the same reason.
- **A Linux-only test failure** turned out to be a real defect, not a
platform quirk: `SetPose` published the *commanded* interpolated pose
beside joint frames derived from the *solved* joints, so the two
disagreed by the inverse-kinematics residual — about 8 mm, constant
after any real motion. That is the lying-digital-twin defect one level
deeper than the per-step IK fix reached. `SetPose` now derives both from
the joint angles.
- **Three source-generator tests** asserted the old emitted shape. The
clause 6.2 Null-Variant fix was implemented in
`ObjectTypeProxyGenerator` so every generated proxy benefits, which
changed that shape; the tests are updated and strengthened to pin the
`IsNull` branch as well.
- **A CI-only timeout** in the simulated arm drain: the executor runs on
a manual clock so the tests do not depend on machine speed, but the
drain guarded itself with a wall-clock deadline, which put that
dependence back. CI runs with coverage instrumentation, which is enough
to take a per-step IK probe from ~0.6 s to over 5 s. The guard is now a
simulated step budget.

One failure was **not** from this PR and did not recur: a Roslyn
`AccessViolationException` compiling `Opc.Ua.ISA95` on one leg, while
the Debug leg of the same target passed on identical code and the
Release build succeeds locally.

## Related Issues

- Relates to #3827 — the request that prompted the robotics intent work.
- Builds on #4127.

The companion specification is drafted in the open at
[marcschier/opcua-drafts#47](https://github.com/marcschier/opcua-drafts/pull/47)
(`metaverse-specs/robot-intent/`), with the prior art and the reasoning
behind each decision in the research document beside it. **Nothing in it
is normative or endorsed by the OPC Foundation, and its NodeIds and
namespace URI are provisional** — which is the main reason this is a
draft.

## Checklist

- [x] I have signed the
[CLA](https://opcfoundation.org/license/cla/ContributorLicenseAgreementv1.0.pdf)
and read the
[CONTRIBUTING](https://github.com/OPCFoundation/UA-.NETStandard/blob/master/CONTRIBUTING.md)
doc.
- [x] I have added tests that prove my fix is effective or that my
feature works and increased code coverage.
- [x] I have added all necessary documentation.
- [x] I have verified that my changes do not introduce (new) build or
analyzer warnings.
- [x] I ran **all** tests locally using the **UA.slnx** solution against
at least .net **framework** and .net **10**, and all passed.
- [ ] I fixed **all** failing and flaky tests in the CI pipelines and
**all** CodeQL warnings.
- [ ] I have addressed **all** PR feedback received.

On the test checkbox, precisely: the whole `UA.slnx` suite now runs on
net10.0 with **50 of 52 assemblies fully green**, and
`Opc.Ua.Robotics.Tests` passes on **all five** target frameworks
including net472, net8.0 and net9.0 which had never previously been
exercised. The two remaining failures are reproduced identically at the
merge-base and are detailed above, so I have ticked the box; if you
would rather it stayed unticked until those two are green, say so and I
will revert it.

## Points I would most like feedback on

1. **The namespace and NodeIds are provisional.** They come from a draft
specification, not from the OPC Foundation. If this lands before the
model is registered, the identifiers will move.
2. **The model lives in `Opc.Ua.Robotics`.** It is standalone on the
base UA namespace and takes no dependency on OPC 40010, so a separate
`Opc.Ua.RobotIntent` package would arguably be cleaner. Keeping it here
was a deliberate call — this is where the robot-facing API already is —
but it is the easiest thing to change now and the hardest later.
3. **Removing the convention API from #4127 is a breaking change** for
anyone who adopted it. It was explicitly marked non-normative, so I have
assumed that is acceptable — please say if a deprecation period is
wanted instead.
4. **Serial execution** is a deliberate simplification. Concurrent
`None`/`Soft` intents would be an optimisation, not a correction, but it
is worth agreeing that reading.
5. **`samples/Robotics/` reorganisation** moves `MinimalRobotServer`.
Happy to split that into its own commit if it makes review easier.

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 1dab1302-19c5-4a9b-a50c-d97d389713aa
Copilot-Session: a248a589-9a20-4372-868e-5d347e57001b
2026-08-08 09:08:40 +02:00