refactor(webapp): move version history and diagram loading to TanStack Query

.changeset/tanstack-query-webapp.md

@@ -0,0 +1,5 @@
+---
+"@tumaet/webapp": patch
+---
+
+No visible change to the editor. Under the hood, the web app now loads and caches version history, version snapshots, and shared diagrams through one shared data layer instead of hand-written fetching, so the version panel refreshes and reconciles more consistently across tabs and collaborators.

standalone/webapp/.storybook/preview.tsx

@@ -5,6 +5,9 @@ import { DocsContainer } from "@storybook/addon-docs/blocks"
 import { themes } from "storybook/theming"
 import { addons } from "storybook/preview-api"
 import { withTanStackRouter } from "../src/stories/_support/webapp"
+import { QueryClientProvider } from "@tanstack/react-query"
+import { storybookQueryClient } from "../src/stories/_support/queryClient"
+import { VersionRepositoryProvider } from "../src/contexts/VersionRepositoryContext"
 
 type DocsContainerCtx = ComponentProps<typeof DocsContainer>["context"]
 
@@ -213,7 +216,24 @@ const preview: Preview = {
     },
   },
   tags: ["autodocs"],
+  // One clean query cache per story: stories that share a query key but inject
+  // different data would otherwise read each other's cached results.
+  beforeEach: () => {
+    storybookQueryClient.clear()
+  },
   decorators: [
+    // TanStack Query context for components that read server state through
+    // the query hooks (versioning UI, share flow, legal pages). The shared
+    // client lives in _support/queryClient so beforeEach hooks can reset it.
+    // Query cache + the version backend the story's UI talks to (the editor
+    // routes supply the latter in production).
+    (Story) => (
+      <QueryClientProvider client={storybookQueryClient}>
+        <VersionRepositoryProvider kind="remote">
+          <Story />
+        </VersionRepositoryProvider>
+      </QueryClientProvider>
+    ),
     // TanStack router context so any component using <Link>/useNavigate/
     // useLocation renders without crashing. Per-story routes and the active
     // location are set via the `tanstackRouter` parameter.

standalone/webapp/README.md

@@ -6,7 +6,24 @@ Part of the Apollon monorepo — run it from the repo root with `pnpm dev`, not
 
 ## Stack
 
-React 19, TypeScript, Vite, the shadcn-style [`@tumaet/ui`](../../packages/ui) design system (Base UI primitives + Tailwind v4), Storybook, Vitest, Playwright (visual + e2e).
+React 19, TypeScript, Vite, the shadcn-style [`@tumaet/ui`](../../packages/ui) design system (Base UI primitives + Tailwind v4), [TanStack Query](https://tanstack.com/query) for server state, Storybook, Vitest, Playwright (visual + e2e).
+
+## Debugging server state
+
+HTTP data (diagram loads, version history, version snapshots) goes through
+TanStack Query — see [`src/queries`](src/queries) and the boundary note in
+[`src/queryClient.ts`](src/queryClient.ts).
+
+The Query Devtools are **off by default**: their floating button sits
+bottom-right, on top of the editor's minimap, and every other corner is taken
+by the editor's own chrome. Enable them per browser from the console, then
+reload:
+
+```js
+localStorage.setItem("apollon:query-devtools", "1")
+```
+
+They are stripped from production builds regardless.
 
 ## Scripts
 

standalone/webapp/eslint.config.mjs

@@ -4,6 +4,7 @@ import pluginJs from "@eslint/js"
 import tseslint from "typescript-eslint"
 import eslintReact from "@eslint-react/eslint-plugin"
 import reactHooks from "eslint-plugin-react-hooks"
+import pluginQuery from "@tanstack/eslint-plugin-query"
 
 /** @type {import('eslint').Linter.Config[]} */
 export default [
@@ -26,6 +27,9 @@ export default [
   { languageOptions: { globals: globals.browser } },
   pluginJs.configs.recommended,
   ...tseslint.configs.recommended,
+  // TanStack Query correctness rules (exhaustive query keys, stable
+  // QueryClient, no misuse of mutation results).
+  ...pluginQuery.configs["flat/recommended"],
   // recommended-typescript disables the prop-types rules TypeScript already enforces.
   eslintReact.configs["recommended-typescript"],
   {

standalone/webapp/package.json

@@ -49,6 +49,7 @@
     "@resvg/resvg-wasm": "catalog:",
     "@tailwindcss/vite": "catalog:",
     "@tanstack/history": "1.162.0",
+    "@tanstack/react-query": "5.101.2",
     "@tanstack/react-router": "1.170.16",
     "@tumaet/apollon": "workspace:*",
     "@tumaet/ui": "workspace:*",
@@ -80,6 +81,8 @@
     "@storybook/addon-themes": "catalog:",
     "@storybook/addon-vitest": "catalog:",
     "@storybook/react-vite": "catalog:",
+    "@tanstack/eslint-plugin-query": "5.100.4",
+    "@tanstack/react-query-devtools": "5.101.2",
     "@tanstack/router-plugin": "1.168.18",
     "@testing-library/react": "catalog:",
     "@testing-library/user-event": "14.6.1",

standalone/webapp/src/AppProviders.tsx

@@ -1,14 +1,42 @@
 import React, { ReactNode } from "react"
+import { QueryClientProvider } from "@tanstack/react-query"
+import { ReactQueryDevtools } from "@tanstack/react-query-devtools"
 import { EditorProvider, ModalProvider } from "@/contexts"
+import { queryClient } from "@/queryClient"
 
 interface Props {
   children: ReactNode
 }
 
+/**
+ * Query Devtools are opt-in: they float a toggle button over the editor's own
+ * floating chrome, which is in the way far more often than it is useful. Turn
+ * them on per browser with
+ *
+ *   localStorage.setItem("apollon:query-devtools", "1")
+ *
+ * and reload. Read once at module load — the flag is a debugging switch, not
+ * reactive state. Production is unaffected either way: the package swaps
+ * itself for a no-op export when `NODE_ENV !== "development"`.
+ */
+const SHOW_QUERY_DEVTOOLS =
+  import.meta.env.DEV &&
+  (() => {
+    try {
+      return localStorage.getItem("apollon:query-devtools") === "1"
+    } catch {
+      // Storage throws when cookies / site data are blocked.
+      return false
+    }
+  })()
+
 export const AppProviders: React.FC<Props> = ({ children }) => {
   return (
-    <EditorProvider>
-      <ModalProvider>{children}</ModalProvider>
-    </EditorProvider>
+    <QueryClientProvider client={queryClient}>
+      <EditorProvider>
+        <ModalProvider>{children}</ModalProvider>
+      </EditorProvider>
+      {SHOW_QUERY_DEVTOOLS && <ReactQueryDevtools initialIsOpen={false} />}
+    </QueryClientProvider>
   )
 }

standalone/webapp/src/components/modals/ShareDashboardModal.test.tsx

@@ -1,7 +1,9 @@
 import { beforeEach, describe, expect, it, vi } from "vitest"
 import { fireEvent, screen, waitFor } from "@testing-library/react"
 import { ShareDashboardModal } from "./ShareDashboardModal"
+import { QueryClientProvider } from "@tanstack/react-query"
 import { renderWithRouter } from "@/test/renderWithRouter"
+import { createTestQueryClient } from "@/test/queryTestUtils"
 import { usePersistenceModelStore } from "@/stores/usePersistenceModelStore"
 import { DiagramView } from "@/types"
 
@@ -89,7 +91,14 @@ describe("ShareDashboardModal", () => {
 
     const { router } = renderWithRouter(
       <ShareDashboardModal modelId="diagram-1" />,
-      { routePaths: ["/", "/shared/$diagramId"] }
+      {
+        routePaths: ["/", "/shared/$diagramId"],
+        wrapper: (children) => (
+          <QueryClientProvider client={createTestQueryClient()}>
+            {children}
+          </QueryClientProvider>
+        ),
+      }
     )
 
     fireEvent.click(await screen.findByRole("button", { name: "Create" }))

standalone/webapp/src/components/modals/ShareModal.test.tsx

@@ -1,5 +1,6 @@
 import { beforeEach, describe, expect, it, vi } from "vitest"
-import { fireEvent, render, screen } from "@testing-library/react"
+import { fireEvent, screen } from "@testing-library/react"
+import { renderWithQuery } from "@/test/queryTestUtils"
 
 const { sharedIdRef, createMock } = vi.hoisted(() => ({
   sharedIdRef: { value: undefined as string | undefined },
@@ -46,7 +47,7 @@ beforeEach(() => {
 describe("ShareModal", () => {
   it("opens straight on the link for an already-shared diagram, with embed", () => {
     sharedIdRef.value = "shared-xyz"
-    render(<ShareModal />)
+    renderWithQuery(<ShareModal />)
 
     expect(screen.getByLabelText("Copy link")).toBeTruthy()
     expect(screen.getByText("Embed")).toBeTruthy()
@@ -56,7 +57,7 @@ describe("ShareModal", () => {
 
   it("creates the shared diagram exactly once, then shows the link", async () => {
     createMock.mockResolvedValue({ id: "new-1" })
-    render(<ShareModal />)
+    renderWithQuery(<ShareModal />)
 
     fireEvent.click(screen.getByRole("button", { name: "Create share link" }))
     // After creation the link appears and the create button is gone.

standalone/webapp/src/components/modals/useShareableDiagram.ts

@@ -1,4 +1,5 @@
 import { useEffect, useRef, useState } from "react"
+import { useMutation } from "@tanstack/react-query"
 import { toast } from "react-toastify"
 import type { UMLModel } from "@tumaet/apollon"
 import { DiagramView } from "@/types"
@@ -40,6 +41,10 @@ export function useShareableDiagram(
 
   const link = diagramId ? buildSharedDiagramUrl(diagramId, mode) : ""
 
+  const createDiagramMutation = useMutation({
+    mutationFn: (model: UMLModel) => DiagramApiClient.createDiagram(model),
+  })
+
   const create = async (name: string) => {
     if (!modelData) {
       toast.error("This diagram can't be shared right now.")
@@ -52,7 +57,7 @@ export function useShareableDiagram(
         trimmed && trimmed !== modelData.title
           ? { ...modelData, title: trimmed }
           : modelData
-      const { id } = await DiagramApiClient.createDiagram(model)
+      const { id } = await createDiagramMutation.mutateAsync(model)
       addSharedDiagramEntry(id)
       setDiagramId(id)
       setMode(DiagramView.COLLABORATE)

standalone/webapp/src/components/navbar/VersionHistoryButton.tsx

@@ -80,8 +80,8 @@ interface VersionHistoryButtonProps {
  * Discoverable navbar entry point for the version-history sidebar.
  *
  * Renders on any route with an active diagram that has a version backend:
- * `/shared/:id` (collab, RemoteVersionRepository) and `/local/:id`
- * (standalone, LocalVersionRepository). Legacy `/:id` redirects to
+ * `/shared/:id` (collab, the collab backend) and `/local/:id`
+ * (standalone, the local backend). Legacy `/:id` redirects to
  * `/shared/:id`, so it is also covered. The gallery (`/`) and the
  * playground have no active diagram, so the button is hidden.
  */

standalone/webapp/src/components/versioning/ConfirmRestoreModal.tsx

@@ -7,7 +7,7 @@ import {
   AlertDialogFooter,
 } from "@tumaet/ui/components/alert-dialog"
 import { useModalContext } from "@/contexts"
-import type { PendingVersion } from "@/stores/useVersionStore"
+import type { PendingVersion } from "@/types"
 import { log } from "@/logger"
 import { versioningStrings as t } from "./strings"
 

standalone/webapp/src/components/versioning/CurrentVersionRow.tsx

@@ -6,11 +6,8 @@ import {
 } from "lucide-react"
 import type { CSSProperties, FC } from "react"
 import { cn } from "@tumaet/ui/lib/utils"
-import {
-  selectScopedPreview,
-  useVersionStore,
-  type PendingVersion,
-} from "@/stores/useVersionStore"
+import { selectScopedPreview, useVersionStore } from "@/stores/useVersionStore"
+import type { PendingVersion } from "@/types"
 import { useClosePreview } from "@/hooks/useVersionPreviewUrlSync"
 import { relativeTime } from "./relativeTime"
 import {