18 KiB
Monaco Script Editor (Roslyn-backed IntelliSense)
The script editor gives AdminUI users a first-class C# authoring experience for virtual-tag scripts: completions, diagnostics, hover, signature help, document formatting, and context-aware tag-path completions — all backed by the same Roslyn compiler the runtime publish gate uses.
See the design doc for the original rationale and brainstorming record:
docs/plans/2026-06-09-monaco-script-editor-design.md.
Overview
Virtual-tag scripts are C# expression bodies (see VirtualTags.md)
compiled at publish time by ScriptEvaluator against a restricted ScriptSandbox.
Before this feature the AdminUI's script page used a CDN Monaco instance wired
over a hidden textarea via an eval + Task.Delay(50) race — no IntelliSense,
fragile in air-gapped environments, and the editor accepted code that publish
would reject.
The replacement:
- Vendored Monaco served locally — no CDN, air-gap safe.
- Reusable
MonacoEditor.razorcomponent wired into both the ScriptEdit page (/scripts/{id}) and the virtual-tag inline script panel in the UNS TagModal. - Full IntelliSense via a Roslyn backend that analyses the user's source inside
the exact evaluator wrapper
ScriptEvaluatorcompiles, so what the editor accepts/rejects matches publish exactly.
Architecture
┌──────────────────────────── AdminUI (Blazor Server) ───────────────────────────┐
│ │
│ Components/Shared/MonacoEditor.razor ◄── Value/ValueChanged, Height, │
│ │ ReadOnly, ShowToolbar, theme/Format/wrap/minimap toolbar │
│ │ (DotNetObjectReference both ways) │
│ ▼ │
│ wwwroot/js/monaco-init.js ──registers──► completion / hover / signatureHelp / │
│ │ diagnostics / format / inlayHints │
│ │ fetch POST /api/script-analysis/* │
│ ▼ │
│ ScriptAnalysis/ScriptAnalysisEndpoints.cs (minimal-API group, FleetAdmin) │
│ ▼ │
│ ScriptAnalysis/ScriptAnalysisService.cs ── Roslyn over OtOpcUa's real wrapper │
│ ├─ ScriptSandbox.Build(typeof(VirtualTagContext)) (imports + refs) │
│ ├─ CompiledScript.Run(ScriptGlobals<VirtualTagContext>) wrapper │
│ ├─ ForbiddenTypeAnalyzer (sandbox-escape squiggles) │
│ ├─ DependencyExtractor (dynamic-path squiggles) │
│ └─ IScriptTagCatalog (tag-path string-literal completions) │
│ ▼ │
│ wwwroot/lib/monaco/vs/… (vendored Monaco, loaded by monaco-init.js) │
└─────────────────────────────────────────────────────────────────────────────────┘
│ references
▼
Core.Scripting + Scripting.Abstractions (ScriptSandbox, VirtualTagContext,
ScriptGlobals<>, ForbiddenTypeAnalyzer, DependencyExtractor)
Configuration (OtOpcUaConfigDbContext → tag / virtual-tag paths for catalog)
MonacoEditor.razor
src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/MonacoEditor.razor
A reusable Blazor Server component. Key parameters:
| Parameter | Type | Notes |
|---|---|---|
Value |
string |
Two-way bound script source |
ValueChanged |
EventCallback<string> |
Fires on every model change |
Height |
string |
CSS height (default 400px) |
ReadOnly |
bool |
Disables editing; IntelliSense still works |
ShowToolbar |
bool |
Shows the theme/Format/wrap/minimap toolbar |
The component creates the Monaco editor in OnAfterRenderAsync, registers a
DotNetObjectReference so JS can call back into Blazor on value change, and
uses a GUID-keyed container so multiple instances on the same page coexist safely.
External Value changes are pushed to the editor via window.MonacoBlazor.setValue.
monaco-init.js
src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/wwwroot/js/monaco-init.js
Exposes window.MonacoBlazor with createEditor / setValue / getValue / setMarkers / setEditorOption / format / dispose. Registers the six Monaco
language providers for the csharp language at load time; each provider POSTs
to the corresponding /api/script-analysis/* endpoint. Diagnostics are
debounced (~500 ms) to avoid firing on every keystroke.
ScriptAnalysisService
src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/ScriptAnalysis/ScriptAnalysisService.cs
The analysis seam is the private Analyze(userSource) method, which:
- Builds the wrapped document — the user's source is appended after the
OtOpcUa evaluator preamble (usings from
ScriptSandbox.Build, theCompiledScript.Run(ScriptGlobals<VirtualTagContext>)wrapper,var ctx = globals.ctx;, then#line 1so Roslyn reports user-source coordinates for diagnostics). Return type isobjectso one shared script is valid regardless of any virtual tag'sDataType. - Parses the wrapped document as a
CSharpSyntaxTreeand creates aCSharpCompilationagainst theScriptSandboxreference set. - Returns the
SemanticModel,SyntaxTree, and the preamble byte offset (used by every capability to map editor coordinates to wrapped-document offsets).
HTTP Endpoints
All six endpoints live under the /api/script-analysis group, registered by
ScriptAnalysisEndpoints.MapScriptAnalysisEndpoints() (called from
EndpointRouteBuilderExtensions.AddAdminUI / Host/Program.cs) and gated by
the FleetAdmin authorization policy (requires the Administrator role).
| Route | Request DTO | Response DTO | Purpose |
|---|---|---|---|
POST /api/script-analysis/diagnostics |
DiagnoseRequest(Code) |
DiagnoseResponse(Markers) |
Roslyn + ForbiddenType + dynamic-path error markers |
POST /api/script-analysis/completions |
CompletionsRequest(CodeText, Line, Column) |
CompletionsResponse(Items) |
Scope, dot-member, and tag-path completions |
POST /api/script-analysis/hover |
HoverRequest(CodeText, Line, Column) |
HoverResponse(Markdown?) |
Type + XML doc markdown |
POST /api/script-analysis/signature-help |
SignatureHelpRequest(CodeText, Line, Column) |
SignatureHelpResponse(Label?, Parameters?, ActiveParameter) |
Parameter help |
POST /api/script-analysis/format |
FormatRequest(Code) |
FormatResponse(Code) |
NormalizeWhitespace() formatting |
POST /api/script-analysis/inlay-hints |
InlayHintsRequest(Code) |
InlayHintsResponse(Hints) |
Inline type hints (stub — returns empty) |
DTO definitions live in ScriptAnalysis/ScriptAnalysisContracts.cs.
DiagnosticMarker fields: Severity (Monaco values: 8 = error, 4 = warning,
2 = info, 1 = hint), StartLineNumber, StartColumn, EndLineNumber,
EndColumn, Message, Code.
CompletionItem fields: Label, InsertText, Detail, Kind (Monaco kind
string: "Method", "Property", "Field", "Variable", "Class", etc.),
InsertTextRules (0 for plain text, 4 for snippet).
Diagnostics Composition
The diagnostics endpoint combines three sources and returns errors only:
1. Roslyn compile diagnostics
compilation.GetDiagnostics() filtered to DiagnosticSeverity.Error. Warnings
are intentionally excluded: the canonical passthrough pattern
return ctx.GetTag("X").Value; triggers nullable warning CS8605 under
NullableContextOptions.Enable but compiles and publishes fine — flagging it in
the editor would be misleading noise that does not reflect publish reality.
Line numbers are read from GetMappedLineSpan() (not GetLineSpan()).
GetMappedLineSpan honours the #line 1 directive in the preamble, so it
returns user-source coordinates directly. Diagnostics whose
SourceSpan.Start < preambleLength are dropped — they are phantom wrapper
diagnostics (e.g. CS0161 "not all code paths return a value" on the synthesized
Run method body when the user has not yet typed return) and are not the
user's fault.
2. ForbiddenTypeAnalyzer
ForbiddenTypeAnalyzer.Analyze(compilation) walks the wrapped syntax tree and
resolves every referenced symbol against the sandbox deny-list (namespace
prefixes System.IO, System.Net, System.Diagnostics, System.Reflection,
System.Threading.Tasks, etc., plus type-granular denials like
System.Environment and System.Threading.Thread). Each violation is mapped
via tree.GetMappedLineSpan(span) to user-source coordinates and emitted as an
error marker with code OTSCRIPT_FORBIDDEN.
3. DependencyExtractor
DependencyExtractor.Extract(code).Rejections enumerates every ctx.GetTag /
ctx.SetVirtualTag call whose first argument is NOT a string literal (variable,
concatenation, interpolation). Each rejection carries a TextSpan in
user-source coordinates, emitted as code OTSCRIPT_DYNPATH. This is the exact
same check publish enforces — the editor shows the squiggle where the literal
must appear.
Tag-Path Completion
When the caret is inside the first string-literal argument of a GetTag("…") or
SetVirtualTag("…") invocation, the completion provider delegates to
IScriptTagCatalog instead of the semantic model.
IScriptTagCatalog contract
ScriptAnalysis/IScriptTagCatalog.cs
GetPathsAsync(string? filter, CancellationToken) returns the distinct
runtime-resolvable keys a script may pass to ctx.GetTag /
ctx.SetVirtualTag, optionally filtered by a case-insensitive StartsWith
prefix. The concrete implementation ScriptTagCatalog reads Tag +
VirtualTag rows from OtOpcUaConfigDbContext and projects them as follows:
| Tag category | Resolvable key emitted |
|---|---|
Equipment driver tag (EquipmentId != null) |
Driver FullName extracted from Tag.TagConfig JSON — the verified DependencyMux key |
SystemPlatform / Galaxy tag (EquipmentId == null) |
MXAccess dot-ref: FolderPath.Name when a folder is set, else Name |
| Virtual tag | Leaf Name (best-effort) |
Why only resolvable keys? The live runtime resolves a ctx.GetTag("X")
literal against DriverInstanceActor.AttributeValuePublished.FullReference,
which is the FullName field from Tag.TagConfig
(see Phase7Composer.ExtractTagFullName + EquipmentNodeWalker.ExtractFullName).
The UNS-path engine (Core.VirtualTags.VirtualTagEngine, keyed by the
slash-joined Enterprise/Site/Area/Line/Equipment/TagName browse path) is
dormant — it is not wired into the host — so UNS browse paths never resolve at
runtime and are intentionally NOT offered as completions.
The catalog is scoped per Blazor circuit; each call creates and disposes its own
DbContext via the pooled factory (same pattern as UnsTreeService). Results
are bounded to 200 entries to keep the completion list responsive on large fleets.
Literal gate
TryGetTagPathLiteral identifies the tag-path context by climbing from the
syntax token under the caret to: LiteralExpressionSyntax → ArgumentSyntax
(first argument only) → ArgumentListSyntax → InvocationExpressionSyntax →
MemberAccessExpressionSyntax. The method name check is
method is "GetTag" or "SetVirtualTag" — it matches by method name only, not
by receiver type, so anything.GetTag("…") would also trigger tag-path
completion. This is harmless in the sandbox (no other GetTag methods exist in
the allowed reference set) and keeps the detection simple.
Vendoring / Air-gap Safety
Monaco is served from
_content/ZB.MOM.WW.OtOpcUa.AdminUI/lib/monaco/vs/ (the Blazor static-asset
path for the AdminUI RCL). The loader script is at
_content/ZB.MOM.WW.OtOpcUa.AdminUI/js/monaco-init.js. No CDN is contacted at
runtime. The legacy CDN loader (monaco-loader.js) and the eval/Task.Delay
injection previously in ScriptEdit.razor have been removed.
Wire-in Points
ScriptEdit page (/scripts/{id})
src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Pages/ScriptEdit.razor
Hosts <MonacoEditor @bind-Value="_form.SourceCode">. On save, SHA-256 is
recomputed from the editor value and stored in Script.SourceHash — unchanged
from the pre-Monaco save path.
VirtualTagModal (/uns TagModal for virtual tags)
src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Uns/VirtualTagModal.razor
When the selected script has a ScriptId, an inline "Script source" panel
renders <MonacoEditor> bound to the script source. The panel shows a
"Used by N virtual tag(s)" notice (populated from
IUnsTreeService.CountVirtualTagsUsingScriptAsync). A dedicated Save script
button calls IUnsTreeService.UpdateScriptSourceAsync, which performs a
RowVersion-guarded update of the Script row — a separate concurrency unit
from the virtual-tag Create/Save operation. Creating a brand-new script inline
from the modal is a follow-up (not v1).
Three IUnsTreeService methods back the inline panel:
GetScriptSourceAsync / CountVirtualTagsUsingScriptAsync /
UpdateScriptSourceAsync.
How to Extend
Adding a new completion source
- Implement a new case in
ScriptAnalysisService.CompleteAsync. TheAnalyze(code)seam gives you theSemanticModel,SyntaxTree, and preamble offset. - Add the corresponding request/response DTOs to
ScriptAnalysisContracts.csif a new endpoint is needed, or fold into an existing endpoint with an extra field. - Register the new Monaco provider in
monaco-init.jsusing the samefetch('/api/script-analysis/…', { method: 'POST', … })pattern.
Adding a new analysis check (diagnostics)
Extend Diagnose in ScriptAnalysisService. The existing three-source pattern
(Roslyn → ForbiddenTypeAnalyzer → DependencyExtractor) is additive: add a
fourth source and append to markers. Keep severity at 8 (Monaco error) for
anything that blocks publish; use 4 (warning) for advisory-only hints.
Changing the tag-path catalog source
Replace or extend the ScriptTagCatalog implementation of IScriptTagCatalog.
Register the replacement in EndpointRouteBuilderExtensions.AddAdminUI
(or inject via the DI container as the IScriptTagCatalog scoped service).
Known Limitations / Follow-ups
- Tag-path completion shows resolvable keys only. Surfacing the UNS browse path as a completion detail (a non-inserted hint shown alongside the resolvable key) for discoverability is a tracked follow-up.
- Literal gate matches by method name, not receiver.
anything.GetTag("…")would also trigger tag-path completion (not justctx.GetTag("…")). Harmless in the sandbox today — no otherGetTagmethods exist in the allowed reference set — but tighter binding toctx/VirtualTagContextis a follow-up. - Analysis runs synchronous Roslyn (CPU-bound). Each endpoint call builds a
CSharpCompilationsynchronously. This is intentional: the endpoints are admin-only, client-side debounced (~500 ms), andTask.Runoffload adds unnecessary complexity for infrequent admin use. If concurrency becomes a concern under heavy admin usage, wrapping eachAnalyzecall inTask.Runis the correct fix. - InlayHints is a stub.
/api/script-analysis/inlay-hintsreturns an empty list. Filling it in (parameter name hints from the semantic model) is a follow-up task. - Language providers register globally at Monaco load. The six providers are
registered for the
csharplanguage on the global Monaco instance (loaded once per page inApp.razor). There is no impact today because onlyAdministrator-reachable pages host aMonacoEditor, but if a read-only surface ever embeds the editor the providers will fire (harmlessly — they just get 401 responses from theFleetAdmin-gated endpoints and return empty results). - Creating a new script from the VirtualTagModal inline panel is deferred.
The current inline panel loads and saves an existing
Scriptrow; creating a brand-new script requires a separate create flow and is a follow-up.
Testing
Unit tests live in
tests/Server/ZB.MOM.WW.OtOpcUa.AdminUI.Tests/ScriptAnalysis/:
| File | Covers |
|---|---|
DiagnoseTests.cs |
Clean script (no markers), Roslyn error, ForbiddenTypeAnalyzer violation, dynamic-path rejection, #line mapping |
CompletionTests.cs |
Scope completions, dot-member completions after ctx. |
TagPathCompletionTests.cs |
Tag-path literal completions inside GetTag/SetVirtualTag via a fake IScriptTagCatalog |
HoverSignatureTests.cs |
Hover markdown, signature-help parameter tracking |
FormatTests.cs |
NormalizeWhitespace round-trip |
ScriptTagCatalogTests.cs |
Equipment-tag FullName, Galaxy dot-ref, virtual-tag leaf Name, filter prefix, MaxResults bound |
tests/Server/ZB.MOM.WW.OtOpcUa.AdminUI.Tests/Uns/ScriptSourceServiceTests.cs
covers GetScriptSourceAsync / CountVirtualTagsUsingScriptAsync /
UpdateScriptSourceAsync via the in-memory EF pattern.
No bUnit tests exist for MonacoEditor.razor or VirtualTagModal.razor — the
AdminUI has no bUnit dependency. Razor/JS correctness was proven by live
docker-dev /run (ScriptEdit + UNS TagModal with Monaco, diagnostics, hover,
tag-path completions, Format, inline script save).