feat(help): add in-app User guide drawer; clarify desktop docs scope

Assisted-by: Claude Opus 4.7

Author: PierreRaybaut

doc/userguide/computation-engine.md

@@ -0,0 +1,47 @@
+# Computation engine (Sigima)
+
+The engine that actually computes signals and images is
+[**Sigima**](https://github.com/DataLab-Platform/Sigima), a headless Python
+library shared between desktop DataLab and DataLab-Web. Whatever the host
+application, the algorithms, parameters and numerical results are the same.
+
+## Where the documentation lives
+
+There is **no separate Sigima documentation for the Web**, by design. The
+existing reference on the
+[DataLab project website](https://datalab-platform.com/) — even though its
+screenshots show the Qt desktop UI — describes the same parameters and the
+same outputs as those exposed here.
+
+Useful entry points (desktop-framed but Web-relevant):
+
+- [Signal processing reference](https://datalab-platform.com/en/features/signal/index.html)
+- [Image processing reference](https://datalab-platform.com/en/features/image/index.html)
+- [Sigima API reference](https://sigima.readthedocs.io/)
+
+## How processings appear in DataLab-Web
+
+The menu bar is populated **automatically** by introspecting Sigima's
+catalog (`build_signal_catalog()` / `build_image_catalog()`). When a new
+processing is added to Sigima upstream, it shows up in DataLab-Web at the
+next release without any UI code change.
+
+## Parameter dialogs
+
+Each processing's parameters are described by a
+[`guidata.DataSet`](https://guidata.readthedocs.io/) schema. DataLab-Web
+reads that schema and renders the dialog automatically — the same data
+model that the desktop application uses to draw its Qt forms.
+
+## What the desktop docs do **not** cover
+
+- The **runtime constraints** of the browser (memory limits, OPFS,
+  cross-origin isolation) — see
+  [Differences from desktop DataLab](differences-from-desktop.md).
+- DataLab-Web-specific UI affordances (Plotly toolbar, macro / notebook
+  workers, plugin loader).
+- The TypeScript SDK for embedding DataLab-Web in another web app.
+
+For everything else — operators, filters, fits, detection algorithms,
+units, ROI semantics, HDF5 file format — the desktop documentation is
+authoritative.

doc/userguide/differences-from-desktop.md

@@ -0,0 +1,65 @@
+# Differences from desktop DataLab
+
+DataLab-Web shares the **computation engine** (Sigima) and the **processing
+catalog** with the desktop application: results are bit-for-bit identical for
+the same inputs. The differences listed below are about the **runtime
+environment** and a few UI surfaces, not about the science.
+
+## Runtime
+
+| Topic | Desktop DataLab | DataLab-Web |
+| --- | --- | --- |
+| Python | System CPython | Pyodide (CPython compiled to WebAssembly) |
+| GUI toolkit | Qt + PlotPy | React + TypeScript + Plotly.js |
+| Plotting | PlotPy (Qt) | Plotly.js |
+| Multi-threading | Native threads / processes | Web Workers (one per macro / notebook) |
+| File system | Native I/O | Browser file picker, drag-and-drop, OPFS |
+| Persistence | HDF5 on disk | HDF5 download / upload, IndexedDB workspace cache |
+| Remote control | XML-RPC, FastAPI Web API | In-browser proxy, optional postMessage SDK |
+
+The first load downloads Pyodide (~10 MB) and installs Sigima via
+`micropip`; expect 30–60 s on a cold cache. Subsequent loads are served
+from the browser cache.
+
+## What is intentionally different
+
+- **No native dialogs**. File open / save go through the browser's own
+  pickers; HDF5 workspaces are downloaded as files rather than written
+  in place.
+- **No Qt-only widgets**. PlotPy interactive tools (rotation, polygon
+  picker…) are not available; equivalent flows are reimplemented with
+  Plotly + React when applicable.
+- **Plugins are JavaScript or Python**. JavaScript plugins live alongside
+  the React app; Python plugins are installed into Pyodide at runtime.
+  See [Plugins](#plugins).
+- **Macros and notebooks run in Web Workers**. They have their own Pyodide
+  instance and communicate with the main runtime through a structured
+  proxy (`MacroRuntime`, `proxyBridge`). Long-running computations no
+  longer freeze the UI.
+- **Web API server is replaced by the in-browser SDK**. Embedding
+  DataLab-Web in another web app is done via the
+  [`@datalab-platform/web-sdk`](https://github.com/DataLab-Platform/web/tree/main/packages/sdk)
+  package and `postMessage`, not HTTP / XML-RPC.
+
+## What is intentionally **not** different
+
+- The **object model** (`SignalObj`, `ImageObj`, ROI, groups) is identical.
+- The **processing catalog** is discovered from Sigima — every function
+  registered there appears in the menu bar with the same parameters.
+- **Parameter dialogs** are auto-generated from the same guidata `DataSet`
+  schemas as in the desktop app.
+- **HDF5 workspace files** are interoperable: a workspace saved in
+  desktop DataLab can be opened in DataLab-Web (and vice versa, within
+  the limits of available processings).
+
+## Plugins
+
+JavaScript plugins are loaded from `plugins/` at startup; Python plugins
+are installed via `micropip` and registered through the same hook system
+as the desktop app. See [Plugins](plugins.md) for the practical guide.
+
+## Macros and notebooks
+
+See [Notebooks](notebooks.md) for the architecture and behaviour of the
+notebook subsystem. Macros follow the same model: a dedicated Pyodide
+worker, a proxy bridge to the main runtime, structured cell results.

doc/userguide/welcome.md

@@ -0,0 +1,37 @@
+# Welcome to DataLab-Web
+
+DataLab-Web is the **browser-native** sibling of the DataLab desktop
+application. It runs the same scientific computation engine — **Sigima** —
+entirely client-side via [Pyodide](https://pyodide.org/) (CPython compiled to
+WebAssembly). No data leaves your browser.
+
+## What you can do here
+
+- Load **signals** (1D curves) and **images** (2D arrays) from the file
+  system or drag-and-drop them into the workspace.
+- Apply the full Sigima processing catalog: arithmetic, filtering, FFT,
+  fitting, peak detection, morphology, segmentation, ROI extraction…
+- Interact with results via [Plotly.js](https://plotly.com/javascript/)
+  plots (zoom, pan, hover, export to PNG/SVG).
+- Organise objects into groups, switch between **Signal** and **Image**
+  panels, persist your workspace as an HDF5 file.
+- Automate workflows with **macros** and **notebooks** running in dedicated
+  Web Workers so the UI stays responsive.
+- Extend the application with **plugins** (Python or JavaScript) and a
+  **TypeScript SDK** for embedding DataLab-Web in third-party apps.
+
+## Where to find help
+
+This in-app **User guide** focuses on what is specific to DataLab-Web. For
+everything that is shared with the desktop application — and that is the
+majority — refer to the
+[DataLab project website](https://datalab-platform.com/), keeping in mind
+its desktop-centric framing.
+
+When in doubt, the **AI assistant** (open it from the right edge of the
+workspace) can answer most questions interactively.
+
+## Reporting issues, contributing
+
+DataLab-Web is open source. Issues and pull requests are welcome on
+[github.com/DataLab-Platform/web](https://github.com/DataLab-Platform/web).

src/App.tsx

@@ -69,6 +69,7 @@ import {
 import { TextImportWizard } from "./components/TextImportWizard";
 import { SidePanel } from "./components/SidePanel";
 import { AIAssistantPanel } from "./components/AIAssistant/AIAssistantPanel";
+import { UserGuidePanel } from "./components/userguide/UserGuidePanel";
 import { AISettingsDialog } from "./components/AIAssistant/AISettingsDialog";
 import { Splitter } from "./components/Splitter";
 import { MacroPanel, type MacroPanelHandle } from "./components/MacroPanel";
@@ -314,6 +315,7 @@ export default function App() {
   } | null>(null);
   const [editingMeta, setEditingMeta] = useState<ObjectMeta | null>(null);
   const [helpView, setHelpView] = useState<HelpView | null>(null);
+  const [userGuideOpen, setUserGuideOpen] = useState(false);
   const [h5BrowserFiles, setH5BrowserFiles] = useState<H5BrowserFile[] | null>(
     null,
   );
@@ -1957,6 +1959,7 @@ export default function App() {
         onShowAbout: () => setHelpView("about"),
         onShowShortcuts: () => setHelpView("shortcuts"),
         onShowConsole: () => setHelpView("console"),
+        onOpenUserGuide: () => setUserGuideOpen(true),
       }),
       ...buildViewActions({
         showResultsOverlay,
@@ -2382,6 +2385,11 @@ export default function App() {
             />
           </div>
         )}
+        {userGuideOpen && (
+          <div className="userguide-floating-host">
+            <UserGuidePanel onClose={() => setUserGuideOpen(false)} />
+          </div>
+        )}
       </div>
       {showAISettings && (
         <AISettingsDialog onClose={() => setShowAISettings(false)} />

src/actions/registry.ts

@@ -139,6 +139,7 @@ export interface HelpActionCallbacks {
   onShowAbout: () => void;
   onShowShortcuts: () => void;
   onShowConsole: () => void;
+  onOpenUserGuide: () => void;
 }
 
 /** Wire Help / "?" menu actions. */
@@ -147,11 +148,19 @@ export function buildHelpActions(cb: HelpActionCallbacks): ActionDescriptor[] {
   const always = () => true;
   return [
     {
-      id: "help.documentation",
-      label: "Online documentation",
-      menuPath: "Help/Online documentation",
+      id: "help.userguide",
+      label: "User guide",
+      menuPath: "Help/User guide",
       iconUrl: getHelpIconUrl("libre-gui-help.svg"),
       enabled: always,
+      run: cb.onOpenUserGuide,
+    },
+    {
+      id: "help.documentation",
+      label: "DataLab project website",
+      menuPath: "Help/DataLab project website",
+      iconUrl: getHelpIconUrl("libre-gui-globe.svg"),
+      enabled: always,
       run: () =>
         window.open(
           "https://datalab-platform.com/",

src/assets/icons/help/libre-gui-globe.svg

@@ -117,6 +117,21 @@ function AboutView({ version }: { version: string }) {
         computation engine runs entirely client-side via Pyodide (CPython
         compiled to WebAssembly); no data leaves your browser.
       </p>
+      <div className="help-about-doc-scope" role="note">
+        <strong>About the online documentation.</strong> The{" "}
+        <a
+          href="https://datalab-platform.com/"
+          target="_blank"
+          rel="noopener noreferrer"
+        >
+          DataLab project website
+        </a>{" "}
+        is centred on the desktop application. Because DataLab-Web shares the
+        same computation engine (Sigima) and the same processing catalog, most
+        of that content remains directly relevant. Web-specific differences
+        (in-browser execution via Pyodide, persistence, plugins, macros,
+        notebooks) are not covered there.
+      </div>
       <ul className="help-about-links">
         <li>
           <a
@@ -125,7 +140,13 @@ function AboutView({ version }: { version: string }) {
             rel="noopener noreferrer"
           >
             DataLab project website
-          </a>
+          </a>{" "}
+          <span
+            className="help-about-link-tag"
+            title="Centred on the DataLab desktop application"
+          >
+            desktop-focused
+          </span>
         </li>
         <li>
           <a