Refactor ElementPickerSubsystem and enhance Query dialog functionality

.reviewmark.yaml

@@ -358,6 +358,67 @@ reviews:
       - src/**/AppShellSubsystem/ViewBuilderDialogView.axaml
       - src/**/AppShellSubsystem/ViewBuilderDialogView.axaml.cs
       - test/**/AppShellSubsystem/ViewBuilderDialogViewModelTests.cs
+  - id: SysML2Workbench-AppShellSubsystem-QueryDialog
+    title: Review that SysML2Workbench AppShellSubsystem QueryDialog Implementation
+      is Correct
+    context:
+      - docs/design/sysml2-workbench.md
+      - docs/reqstream/sysml2-workbench.yaml
+      - docs/design/sysml2-workbench/app-shell-subsystem.md
+      - docs/reqstream/sysml2-workbench/app-shell-subsystem.yaml
+    paths:
+      - docs/reqstream/sysml2-workbench/app-shell-subsystem/query-dialog.yaml
+      - docs/design/sysml2-workbench/app-shell-subsystem/query-dialog.md
+      - docs/verification/sysml2-workbench/app-shell-subsystem/query-dialog.md
+      - src/**/AppShellSubsystem/QueryDialogViewModel.cs
+      - src/**/AppShellSubsystem/QueryDialogView.axaml
+      - src/**/AppShellSubsystem/QueryDialogView.axaml.cs
+      - test/**/AppShellSubsystem/QueryDialogViewModelTests.cs
+  - id: SysML2Workbench-ElementPickerSubsystem
+    title: Review that SysML2Workbench ElementPickerSubsystem Implementation is Correct
+    context:
+      - docs/design/sysml2-workbench.md
+      - docs/reqstream/sysml2-workbench.yaml
+    paths:
+      - docs/reqstream/sysml2-workbench/element-picker-subsystem.yaml
+      - docs/design/sysml2-workbench/element-picker-subsystem.md
+      - docs/verification/sysml2-workbench/element-picker-subsystem.md
+      - src/**/ElementPickerSubsystem/**
+      - test/**/ElementPickerSubsystem/**
+  - id: SysML2Workbench-ElementPickerSubsystem-ElementPicker
+    title: Review that SysML2Workbench ElementPickerSubsystem ElementPicker Implementation
+      is Correct
+    context:
+      - docs/design/sysml2-workbench.md
+      - docs/reqstream/sysml2-workbench.yaml
+      - docs/design/sysml2-workbench/element-picker-subsystem.md
+      - docs/reqstream/sysml2-workbench/element-picker-subsystem.yaml
+    paths:
+      - docs/reqstream/sysml2-workbench/element-picker-subsystem/element-picker.yaml
+      - docs/design/sysml2-workbench/element-picker-subsystem/element-picker.md
+      - docs/verification/sysml2-workbench/element-picker-subsystem/element-picker.md
+      - src/**/ElementPickerSubsystem/ElementPickerViewModel.cs
+      - src/**/ElementPickerSubsystem/ElementPickerView.axaml
+      - src/**/ElementPickerSubsystem/ElementPickerView.axaml.cs
+      - src/**/ElementPickerSubsystem/ElementTypeLabeler.cs
+      - test/**/ElementPickerSubsystem/ElementPickerViewModelTests.cs
+      - test/**/ElementPickerSubsystem/ElementTypeLabelerTests.cs
+  - id: SysML2Workbench-ElementPickerSubsystem-ElementFilter
+    title: Review that SysML2Workbench ElementPickerSubsystem ElementFilter Implementation
+      is Correct
+    context:
+      - docs/design/sysml2-workbench.md
+      - docs/reqstream/sysml2-workbench.yaml
+      - docs/design/sysml2-workbench/element-picker-subsystem.md
+      - docs/reqstream/sysml2-workbench/element-picker-subsystem.yaml
+    paths:
+      - docs/reqstream/sysml2-workbench/element-picker-subsystem/element-filter.yaml
+      - docs/design/sysml2-workbench/element-picker-subsystem/element-filter.md
+      - docs/verification/sysml2-workbench/element-picker-subsystem/element-filter.md
+      - src/**/ElementPickerSubsystem/ElementFilterViewModel.cs
+      - src/**/ElementPickerSubsystem/ElementFilterView.axaml
+      - src/**/ElementPickerSubsystem/ElementFilterView.axaml.cs
+      - test/**/ElementPickerSubsystem/ElementFilterViewModelTests.cs
   - id: OTS-DemaConsultingSysML2Tools
     title: Review that DemaConsulting.SysML2Tools Provides Required Functionality
     paths:

docs/design/introduction.md

@@ -5,7 +5,7 @@ for SysML v2 textual models. It is built as a thin shell over the
 `DemaConsulting.SysML2Tools` OTS libraries (parser, semantic model, layout
 engine) and the `DemaConsulting.Rendering` OTS library, all consumed as
 published NuGet packages. Local design coverage is organized as one system,
-seven subsystems (no nesting), and eleven units. There are no Shared Packages
+eight subsystems (no nesting), and fifteen units. There are no Shared Packages
 in this repository; OTS items are documented under the parallel `ots/`
 folders.
 
@@ -70,8 +70,15 @@ thin bootstrap/entry-point project with no independent design of its own.
     - **DiagnosticsListView** (Unit) — structured for future click-to-navigate
   - **LoggingSubsystem**
     - **RollingFileLogger** (Unit) — local rolling log file for user-attachable bug reports
+  - **ElementPickerSubsystem** — reusable dialog-agnostic element-picker control
+    - **ElementFilter** (Unit) — chip/search filter-only view model + view, composed by ElementPicker for selection-bearing callers
+    - **ElementPicker** (Unit) — chip/search/list view model + view for a caller-built candidate list
   - **AppShellSubsystem** — window, navigation, tabbed views
     - **MainWindowShell** (Unit)
+    - **WorkspacePanel** (Unit) — workspace tree panel view model
+    - **AboutDialog** (Unit) — modal about dialog
+    - **ViewBuilderDialog** (Unit) — modal custom-view builder dialog
+    - **QueryDialog** (Unit) — modal query dialog (Browse + Element Query tabs)
     - Desktop (platform head / entry point project; not a separately documented unit)
 
 ## Folder Layout

docs/design/sysml2-workbench/app-shell-subsystem.md

@@ -7,7 +7,8 @@
 AppShellSubsystem is the composition root for the desktop application. It owns
 the main window, navigation flow, and tabbed viewing experience that tie the
 other subsystems into one coherent user workflow. Its documented units are
-MainWindowShell, WorkspacePanel, AboutDialog, and ViewBuilderDialog. The thin
+MainWindowShell, WorkspacePanel, AboutDialog, ViewBuilderDialog, and
+QueryDialog. The thin
 desktop platform head remains outside the documented unit set because it is
 only a bootstrap and lifetime host.
 

docs/design/sysml2-workbench/app-shell-subsystem/query-dialog.md

@@ -0,0 +1,207 @@
+### QueryDialog
+
+![AppShellSubsystem Structure](AppShellSubsystemView.svg)
+
+#### Purpose
+
+QueryDialog is the modal dialog opened from the main window's Query menu
+("_Run Query...") that lets the user browse or query the currently-loaded
+workspace through a single, always-visible adaptive form — there is no
+`TabControl` and no explicit "Run" gesture anywhere in this design:
+
+- A "Query Type" combo box offers eleven choices: a merged **List** entry
+  first (a purely-client-side filter over every workspace declaration,
+  respecting the global "Include standard library" checkbox), followed by
+  the ten element-scoped `QueryVerb` operations (`Describe`, `Uses`,
+  `UsedBy`, `Dependencies`, `Impact`, `Hierarchy`, `Requirements`,
+  `Interface`, `Connections`, `States`) dispatched through
+  `DemaConsulting.SysML2Tools.Query.QueryEngine.Execute`. The user never
+  sees `QueryVerb.Find`: "List" always resolves to the client-side filter,
+  never to a `QueryEngine.List`/`Find` call.
+- Below the combo, one of two controls is shown: for **List**, a
+  selection-free filter control (chip row + search box only); for every
+  other Query Type, the full element picker (the same chip row + search
+  box, plus a selectable candidate list used as the target-element
+  selector).
+- Verb-specific extra controls appear only when relevant: a "Direction"
+  combo for `Hierarchy`, and a "Walk depth" text box for `Impact`.
+- Every interaction — Query Type selection, chip add/remove, search text,
+  element selection, Direction change, Walk depth text change, or the
+  Include-standard-library toggle — immediately recomputes and displays the
+  result synchronously; there is no "Run Query" button.
+
+Results feed the same shared results panel: a summary bullet list plus a
+`Grid`-based (not `DataGrid`) entries table with columns for Qualified Name,
+Kind, Detail, and a Direction column shown only when the current result is a
+`dependencies` verb result. There is no toolbar: "Copy as Markdown" and
+"Copy as JSON" are right-click `ContextMenu` items on the results panel,
+wired to `QueryResultRenderer.RenderMarkdown`/`RenderJson` via the same
+`AvaloniaClipboardService` pattern `DiagramDocumentView` uses for its "Copy
+as SysML" action, and enabled through a `HasCurrentResult` binding mirroring
+`DiagramDocumentViewModel.CanCopyAsSysml`.
+
+It is documented as one unit covering both `QueryDialogViewModel` (the
+Avalonia-free composition and dispatch state) and `QueryDialogView` (the
+Avalonia `Window` shown via `ShowDialog`), matching the pairing convention
+used by the sibling `ViewBuilderDialog` unit. Like the other dialogs in this
+subsystem, `QueryDialog` is not a Dock tool: it is a short-lived, owned
+dialog `Window`, constructed fresh every time the user opens it.
+
+#### Data Model
+
+**Shell**: `MainWindowShell` — the shared application shell, used to resolve
+candidate elements (`CurrentWorkspace.Workspace.Declarations`) and to run
+queries against (`CurrentWorkspace.Workspace` handed to
+`QueryEngine.Execute`).
+
+**FilterOnly**: an `ElementPickerSubsystem.ElementFilterViewModel` instance
+used exclusively when `SelectedQueryType` is `List`: its `DisplayedItems` is
+the client-side result source. Has no selection concept, matching "List"'s
+lack of a target-element concept.
+
+**Picker**: an `ElementPickerSubsystem.ElementPickerViewModel` instance used
+for the ten element-scoped Query Types (every `QueryVerb` other than the
+merged `List` entry): its `SelectedQualifiedName` is the target element
+(its `DisplayedItems` remains visible purely as a filter aid narrowing which
+candidates are selectable).
+
+**QueryTypes**: `IReadOnlyList<QueryVerb>` — the eleven Query Type options
+the combo box binds to, `List` first, never containing `Find`.
+
+**IncludeStdlib**: `bool` — the global "Include standard library" checkbox
+state, threaded through both `RefreshFromWorkspace` (as a candidate-filter
+choice) and `BuildOptions` (as the `QueryOptions.IncludeStdlib` value for
+every engine call).
+
+**IsWorkspaceEmpty**: `bool` — `true` when the shell's current workspace has
+zero sources, used to show the dialog's own empty-state hint alongside the
+checkbox.
+
+**SelectedQueryType**: `QueryVerb` — the currently-selected Query Type;
+defaults to `List` (the always-available, no-selection-required option).
+
+**HierarchyDirection**: `string?` — the direction option accepted by the
+Hierarchy verb (`"up"`, `"down"`, or `"both"`); defaults to `"both"`. Only
+attached to `QueryOptions.Direction` when `SelectedQueryType` is `Hierarchy`.
+
+**WalkDepthText**: `string?` — the free-text input for the Impact verb's
+optional walk-depth bound. Only parsed for `Impact`, and only when it parses
+cleanly as a non-negative integer.
+
+**CurrentResult**: `QueryResult?` — the most recently produced `QueryResult`
+(either List's client-built list result or the engine's response), or
+`null` when an element-scoped Query Type has no selection yet. Feeds the
+shared results panel.
+
+**CurrentResultRows**: `IReadOnlyList<QueryResultRow>` — a flattened,
+view-friendly projection of `CurrentResult.Entries` (empty strings replacing
+nullable fields, `Direction` mapped to a human-readable label, notes joined
+into a tooltip string), bound directly by the results-panel `ItemsControl`.
+
+**StatusMessage**: `string?` — user-visible error/hint text set on every
+recoverable failure or prompt (no workspace, no selection yet, engine
+argument rejection). Cleared on a successful recompute.
+
+**HasCurrentResult**: `bool` — computed mirror of `CurrentResult is not
+null`, bound by the results panel's right-click context-menu items'
+`IsEnabled` so the copy actions are only enabled when there is something to
+copy.
+
+**ClipboardService**: `IClipboardService?` — the same clipboard-write seam
+`DiagramDocumentViewModel` uses. Assigned by `QueryDialogView` to an
+`AvaloniaClipboardService` anchored on the dialog's own `Window`.
+
+#### Key Methods
+
+**RefreshFromWorkspace**: Refreshes both `FilterOnly`'s and `Picker`'s
+candidate lists (from the same candidate set) and `IsWorkspaceEmpty` from
+the shell's current workspace, then recomputes the result.
+
+- *Parameters*: none.
+- *Returns*: `void` — both `FilterOnly.SetCandidates` and `Picker.SetCandidates`
+  are called with the full candidate list (no default chip for either), and
+  `RecomputeResult` runs immediately afterward.
+- *Postconditions*: Called once at construction and again on every
+  `IncludeStdlib` toggle; the dialog does not itself subscribe to
+  `MainWindowShell.SourcesChanged`, matching the sibling dialogs' pattern.
+  Because `ElementPickerViewModel.SetCandidates` unconditionally clears any
+  prior `SelectedQualifiedName`, a stale selection can never linger past a
+  workspace-derived refresh.
+
+**RecomputeResult**: Recomputes `CurrentResult`/`CurrentResultRows` for the
+currently selected `SelectedQueryType`. This is the redesign's entire
+"no explicit Run gesture" mechanism, invoked automatically by every relevant
+property change (Query Type, Hierarchy direction, Walk depth text, and — via
+`FilterOnly`'s and `Picker`'s `PropertyChanged` subscriptions —
+`FilterOnly.DisplayedItems`/`Picker.DisplayedItems`/`Picker.SelectedQualifiedName`).
+
+- *Parameters*: none.
+- *Returns*: `void` — `CurrentResult`, `CurrentResultRows`, and
+  `StatusMessage` update in place.
+- *Postconditions*: For `List`, delegates to `BuildListResult`. For every
+  other Query Type: with no workspace, reports the existing empty-workspace
+  message; with no `Picker.SelectedQualifiedName`, reports a helpful
+  (non-error) prompt naming the Query Type and clears any stale prior
+  result; otherwise dispatches through `QueryEngine.Execute`, gracefully
+  catching `ArgumentException`. Never throws.
+
+**BuildListResult**: Rebuilds `CurrentResult` and `CurrentResultRows` from
+`FilterOnly`'s `DisplayedItems`.
+
+- *Parameters*: none.
+- *Returns*: `void` — `CurrentResult` becomes a `QueryResult` with
+  `Verb="list"`, `Element=null`, one entry per displayed item.
+- *Postconditions*: "List" is deliberately a purely-client-side filter; it
+  does NOT call `QueryEngine.List`/`Find`. Invoked by `RecomputeResult`
+  whenever `SelectedQueryType` is `List`.
+
+**BuildOptions**: Builds a `QueryOptions` instance reflecting the current
+form's verb-specific state.
+
+- *Parameters*: `string qualifiedName` — the resolved target's qualified name.
+- *Returns*: `QueryOptions` — always carries `IncludeStdlib`; attaches
+  `Direction` only for `Hierarchy`; parses `WalkDepth` only for `Impact` and
+  only when the text parses cleanly.
+
+**CopyResultAsMarkdownAsync** / **CopyResultAsJsonAsync**: Copy
+`CurrentResult` to the clipboard through `QueryResultRenderer` and
+`ClipboardService`.
+
+- *Parameters*: none.
+- *Returns*: `Task` — completes once the clipboard write has finished.
+- *Postconditions*: A safe no-op (rather than an exception) when
+  `CurrentResult` or `ClipboardService` is `null`.
+
+#### Error Handling
+
+QueryDialog treats every recoverable failure or informational prompt - no
+workspace, no selection yet for an element-scoped Query Type, a picker
+qualified name that vanished under a mid-session workspace change, or an
+engine `ArgumentException` (thrown when the verb requires an element and
+none is resolvable, or when the verb value itself is out of range) - as a
+locally recoverable condition surfaced through `StatusMessage` rather than
+an unhandled exception. Unlike the prior "leave the last result visible"
+behavior, every one of these paths also clears `CurrentResult`/
+`CurrentResultRows` so the results panel never shows a stale result left
+over from a previous Query Type or selection.
+
+#### Dependencies
+
+- **MainWindowShell** — supplies `CurrentWorkspace` for candidate resolution
+  and for the workspace argument passed to `QueryEngine.Execute`.
+- **ElementPickerSubsystem** — `ElementFilter` via `FilterOnly` (used for
+  "List"); `ElementPicker` via `Picker` (used for the other ten
+  element-scoped Query Types).
+- **DemaConsulting.SysML2Tools.Query** — `QueryEngine.Execute` runs the
+  verb, `QueryResultRenderer.RenderMarkdown`/`RenderJson` produces the
+  clipboard text.
+- **IClipboardService** / **AvaloniaClipboardService** — the clipboard-write
+  seam shared with `DiagramDocumentViewModel`.
+- **Avalonia** — `QueryDialogView` is a `Window` shown modally via
+  `ShowDialog`, mirroring `AboutDialogView` and `ViewBuilderDialogView`.
+
+#### Callers
+
+- **MainWindowView** — constructs `QueryDialogView` and calls
+  `ShowDialog(this)` when the user selects the Query menu's "Run Query..."
+  item, so the dialog is owned by and centers over the main window.