explanation

LabKit App SDK

labkit.app is the MATLAB App SDK above LabKit's GUI-free domain libraries. Apps own scientific workflow, calculations, units, wording, plots, and exports. The SDK owns semantic layout, transactions, project documents, portable sources, dialogs, resources, results, and native component lifecycle.

Start Here

SDK Map

The required path has three concepts:

Read an App in this order: definition.m shows its complete contract, +workbench/buildLayout.m shows the user workflow, and its capability packages show the controls, state transitions, presentation, and rendering owned by each feature. Open projectSpec.m or createSession.m only when the definition names those optional capabilities.

Layout controls bind directly to named App callbacks, and plot areas bind directly to their renderer. Apps do not maintain handler, renderer, or capability registries. Runtime-injected values are labkit.app.CallbackContext and typed labkit.app.event.* payloads. Callbacks name those boundary values explicitly and delegate domain work through narrow inputs.

Optional capabilities are grouped by purpose:

Smallest App

function app = definition()
    workbench = labkit.app.layout.workbench({ ...
        labkit.app.layout.field("gain", Label="Gain", ...
            Kind="numeric", Bind="project.parameters.gain"), ...
        labkit.app.layout.button("run", "Run", @runAnalysis, ...
            Tooltip="Compute the result from the current gain.")});
    app = labkit.app.Definition( ...
        Entrypoint="labkit_Example_app", AppId="example", ...
        Title="Example", Family="Examples", ...
        AppVersion="1.0.0", Updated="2026-07-19", ...
        Requirements=labkit.contract.requirements("app", ">=1 <2"), ...
        Workbench=workbench);
end

The entrypoint calls definition().launch(...). Definition compiles the immutable semantic graph before creating a figure, validates direct callback and renderer signatures, and builds one private native platform plan.

Paved Road

• Bind ordinary state with Bind="project..." or Bind="session...".
• Use labkit.app.layout.fileList for portable file records and selection. Set AllowDuplicatePaths=true only when separate workflow tasks may share one resolved path, and present row-level workflow state with Snapshot.fileItemStatuses. Source changes rebuild the transient session; Apps do not mirror choose, remove, clear, or selection UI events.
• Give every scientific or workflow action an App-owned Tooltip. The framework guarantees a nonempty label-based fallback, while repository guardrails require tracked Apps to explain the action instead of repeating its visible label. File-list choose/folder/remove/clear controls expose dedicated tooltip options and domain-neutral label defaults.
• Rebuild transient data with session = createSession(project,context) and resolve opaque source records with context.resolveSourcePaths.
• Return only derived view state from labkit.app.view.Snapshot; runtime supplies layout defaults, bindings, file state, log text, and status text.
• Give short statusPanel summaries an explicit Lines hint so the native layout reserves detail height only for genuinely multiline content.
• Use labkit.app.layout.dataTable with labkit.app.event.TableCellEdit and labkit.app.event.TableCellSelection; Apps never decode native events.
• Use labkit.app.layout.plotArea and a fixed renderer(axesById,model) callback. axesById is always a named struct, even when the plot area declares only one axis.
• Pass a transient ViewRevision to Snapshot.renderPlot when an App exposes an explicit reset-view action. The adapter preserves user zoom while the revision is unchanged and accepts renderer-fitted limits once when it changes.
• Pass one workspace node or a row cell array of vertically arranged nodes to workspace.page; growable tables and plots share the available page height without an App-authored wrapper section.
• Use layout.group(..., Title="...") for a nested reader-facing control boundary inside a section; leave Title blank for arrangement-only groups.
• A control tab containing one growable file list, table, log, status, or plot surface fills the available tab height. Tabs with longer mixed content remain scrollable.
• Declare editable overlays with labkit.app.interaction.* on the plot area; supply their current values with same-named Snapshot methods.
• Use labkit.app.plot.clearAxes, showMessage, and fitAxesToGraphics for renderer mechanics; EqualDataUnits=true makes a one-time fitted equal-scale view from the settled native axes allocation without dispatching pending UI callbacks, without changing the allocation or locking later zoom. Apps still decide message wording and viewport policy.
• Use labkit.app.project.Schema, labkit.app.result.File, and labkit.app.result.Package only when those optional capabilities exist.
• Use labkit.app.project.sourceRecord only in pure project creation or migration code that must turn a legacy path into a portable source value; runtime callbacks still resolve paths through CallbackContext.

Runtime validates candidate state and the complete view snapshot before publishing either. The private MATLAB adapter maps semantic IDs to native components, preserves plot viewports, normalizes native event differences, and never exposes component registries to Apps.

Normal App launches show the completed native window. Official GUI validation uses the same launch path with a framework-owned visibility policy: hidden keeps the final window off screen and minimized minimizes it after startup. Tests therefore exercise real controls without individual Apps or test methods having to hide the window after launch.

Built-in App Tools

The native runtime installs one top-level Tools menu so framework-owned utilities do not compete with the App's workflow controls:

• Plots opens, copies, or saves the App's plot surfaces.
• Screenshot copies the complete App surface to the system clipboard or saves it to an image file.
• Project State saves or loads the current project document when the App declares a project schema.

These actions are framework-owned native behavior. Apps do not declare menu items, implement clipboard integration, or duplicate project persistence callbacks.

Framework concepts and source names are versionless. Compatibility belongs to labkit.app.version; saved-data versions belong to labkit.app.project.Schema.

Related Topics

• App catalog
• App development
• Project history