[Medformatik]

What changed and why

In the installed PWA (and the native app), the system Back gesture closed OpenMapX instead of closing what the user had just opened. DeepLinkManager mirrored all state into the URL with replaceState only, so the history stack never grew past one entry.

Now every surface gets a history entry, and Back closes the most recent one:

Opened	Back does
Place card, category/search results, directions, saved list, data-source item, measure/travel-time tool	Closes it. The map stays where it is, and whatever remains open keeps its state (list, scroll position, loaded place).
Dialog, menu, popover (all of them, via wrappers)	Closes it, like Escape.
Drawer menu, full-screen search, photo gallery, map-click card	Closes it.
Bottom sheet expanded to full height	Lowers it to the middle detent. The next Back closes its content.
Active turn-by-turn or transit guidance	Ends the trip, like the End button.
Nothing left	Leaves the app, as before.

How it works

• lib/backNavigation.ts is the only code that writes history. navigationPath() (in deepLink.ts) lists the open surfaces and leaves out the camera, base layer and overlays, so panning or toggling a layer still rewrites the current entry.
• Opening something deeper pushes an entry. Closing rewrites the current entry, so a later Back cannot reopen it. Switching between siblings (another place in the same list, another category chip) also rewrites.
• App code never calls history.back(). Next.js treats any popstate as a traversal and cancels a route navigation in flight, so a drawer link that closes the drawer as it navigates would silently stay on the map. Instead, a surface closed by its own control leaves its entry behind. A Back that lands on an entry showing nothing new keeps going, so Back always visibly does something. The next surface to open reuses such an entry, so history doesn't pile up.
• useBackDismiss(open, onBack) gives a transient surface its own entry. components/ui/{Dialog,Menu,Popover} wrap MUI and close on Back the way Escape closes them. All ~60 importers now use them, a Biome noRestrictedImports rule keeps new code on them, and integrations get @/integration-api/components/Dialog.
• Text searches are now encoded as search= in the URL, so a results list survives Back (and sharing).
• Native shell: useHardwareBack sends Android's hardware Back to WebView.goBack() while the page has history; otherwise Back goes to the system. iOS already uses the WebView's swipe-back gesture.

Trade-offs

• History traversal no longer restores camera, base layer, globe or overlays (two existing tests asserted that, and I updated them). A loaded or shared link still restores everything.
• On desktop, browser Back now steps through panels and dialogs as well.
• Forward (desktop only) can land on a leftover entry that changes nothing.

Verification

• Unit tests: historyStep, navigationPath, push/rewrite/reuse rules, layers, step-over of leftover entries (including returning from another page), and the router-navigation case (apps/web/src/lib/backNavigation.test.ts). Also Back in DeepLinkManager (closes the card in place without re-searching the list), the Dialog wrapper, the bottom sheet, and the mobile useHardwareBack/App wiring.
• pnpm exec vitest run --project web: 5723 passed. 8 failures in useNavJunctions.test.tsx and CategoryResultMarkers.test.tsx also fail on an unmodified checkout in this environment.
• pnpm -C apps/mobile run test: 1220 passed. tsc --noEmit passes for web, tsconfig.integrations.json, tsconfig.sw.json and mobile.
• biome check . --diagnostic-level=error, Prettier on the changed docs and pnpm check-translations pass. pnpm check-dead-code reports only findings in files this PR doesn't touch.
• Browser check with Playwright on next dev, 390×844 touch viewport, no API backend. Back closed: the drawer; the Settings dialog opened from the drawer, then the drawer underneath; the directions panel; the full-screen search; the layer popover. Closing directions with its own button didn't leave a Back that reopens it. A drawer link to /settings/offline navigated normally, and Back from there returned to the map. The page didn't reload between steps.
• Not verified: Android hardware Back in a real PWA install or the native app, iOS swipe-back, and flows that need the API (place cards from real search results, active guidance, expanding a sheet by drag).

Release and upgrade impact

No migration or operator action. Contributors must import Dialog, Menu and Popover from @/components/ui/... (integrations: @/integration-api/components/Dialog); lint enforces this.