# Fullscreen Workspace

## Objective

Hide surrounding chrome when users need the whole screen for the work.

A focus mode that removes navigation and sidebars so an editor, canvas, or dashboard fills the viewport.

## Before You Begin

This feature is being added to an application that already exists and already
works. Do not scaffold a new project, and do not assume a blank slate.

Inspect the codebase first and establish:

- The existing application structure and where code of this kind already lives.
- The framework and version in use.
- The existing design system — colours, spacing, typography, and component conventions.
- Existing UI components you can reuse instead of writing new ones.
- The existing database structure, if this feature needs to persist anything.
- The existing authentication and authorization system, if this feature is user-scoped.
- Dependencies already installed, so you don't add a library that duplicates one.
- The existing test setup and conventions.

Only start writing code once you understand the above. If the application
already implements part of this feature, extend it rather than replacing it.

## Implementation Instructions

1. Identify the views where the chrome competes with the work — editors, builders, large tables, dashboards — and add focus mode there only.
2. Implement it as an app-level layout change first. Native browser fullscreen is an optional enhancement on top, because it can be blocked or unavailable.
3. Always show a visible exit control, and bind Escape to exit. Do not rely on the browser's own fullscreen hint, which fades after a few seconds.
4. Keep save status, unsaved-changes indicators, and blocking alerts visible in focus mode. Hiding chrome must not hide whether the user's work is safe.
5. Do not unmount and remount the view when toggling modes. Re-creating the editor loses unsaved state, undo history, and scroll position.

## UI and UX Requirements

Match the application's existing design system exactly. Reuse its components,
spacing, and typography. This feature should look like it was always there.

## Responsive Requirements

Works on mobile, tablet, and desktop. Touch targets are large enough to hit on a
phone, and nothing overflows horizontally at 320px.

## Accessibility Requirements

- Fully keyboard navigable.
- Correct semantic elements and ARIA roles.
- Visible focus states.
- Meets WCAG AA contrast.
- Dynamic changes are announced to screen readers.
- Respects prefers-reduced-motion.

## Edge Cases

- If the browser denies or exits fullscreen, the app must fall back to its own focus layout rather than getting stuck in a half state.
- Exiting must restore the previous layout, scroll position, and selection.
- Modals, toasts, and command palettes must render above the fullscreen surface, not behind it.
- Entering focus mode while a dialog is open should be refused or should carry the dialog with it.
- The mode should be reflected in state that survives a refresh, or the user is thrown out of focus mode by any reload.
- On mobile, browser chrome and the on-screen keyboard change the usable height — measure the real viewport rather than assuming full screen height.

## Testing

Exercise the feature end to end in the running application. Cover every edge case
above, then run the existing test suite and confirm nothing regressed.

## Acceptance Criteria

- [ ] Focus mode works without native browser fullscreen support.
- [ ] An always-visible exit control and Escape both leave the mode.
- [ ] Unsaved state, undo history, and scroll position survive entering and exiting.
- [ ] Save status and blocking alerts remain visible while in focus mode.
- [ ] Overlays render above the fullscreen surface.
- [ ] Exiting restores the exact previous layout.
- [ ] The feature matches the existing design system.
- [ ] No existing functionality is broken.

## Adaptation Rules

- Match the existing design system. Do not introduce a new colour palette,
  spacing scale, or component library.
- Reuse existing components and utilities wherever they fit.
- Follow the naming, file layout, and code style already present.
- Do not upgrade, replace, or remove existing dependencies to make this
  feature fit. Adapt the feature to the app, not the app to the feature.
- Do not break existing functionality. If a change is genuinely required in
  existing code, make the smallest one that works and say so.
- If something in these instructions conflicts with how the application is
  built, follow the application and explain the deviation.

## Final Verification

Before you report the work as done:

1. Re-read the acceptance criteria above and check each one against what you
   actually built.
2. Run the application and exercise the feature end to end.
3. Run the existing test suite and confirm you have broken nothing.
4. Check the feature on mobile, tablet, and desktop widths.
5. Check keyboard navigation and focus handling.
6. Summarize what changed: files added, files modified, and anything you
   deliberately did differently because of how this application is built.

If any acceptance criterion is unmet, fix it before reporting completion.