# 1.1 — App Shell

**Next Step:** → [Status Bar](../1.2-status-bar/1.2-status-bar.md)

---

## Page Metadata

| Property | Value |
|----------|-------|
| **Scenario** | 01 — Workspace Shell |
| **Page Number** | 1.1 |
| **Platform** | Web (PWA), portable to macOS/Windows |
| **Page Type** | Full Application Shell |
| **Viewport** | Desktop-first, responsive to mobile |
| **Interaction** | Mouse + keyboard (primary), touch (secondary) |
| **Visibility** | Public (no auth required) |

---

## Overview

**Page Purpose:** The app shell is the top-level container that defines the spatial structure of the entire CalcText workspace. It arranges all panels (sidebar, editor, results), the tab bar, header, and status bar into a cohesive layout that persists across all user interactions.

**User Situation:** User opens CalcText in a browser. They expect a professional workspace where they can write calculations, manage files, and personalize their environment. First-time users should immediately understand the layout. Returning users should find their documents and preferences exactly as they left them.

**Success Criteria:**
- User understands the 3-panel layout within 3 seconds
- All panels are resizable and collapsible
- Layout state persists across sessions (sidebar width, panel visibility)
- Feels native — not like a web page

**Entry Points:**
- Direct URL (calctext.app or localhost)
- PWA launch from desktop/dock
- Returning session (restores last state from localStorage)

**Exit Points:**
- Close browser/PWA (state auto-saves)
- All navigation is within the shell (no page transitions)

---

## Reference Materials

**Strategic Foundation:**
- [Product Brief](../../../A-Product-Brief/project-brief.md) — Workspace evolution, web-first
- [Brownfield Analysis](../../../A-Product-Brief/01-brownfield-analysis.md) — Current CSS tokens, components, gaps

**Related Pages:**
- [Status Bar](../1.2-status-bar/1.2-status-bar.md) — Bottom status strip
- Tab Bar (Scenario 03) — Document tabs above editor
- Sidebar (Scenario 04) — File tree panel
- Editor (Scenario 02) — Calculation editor
- Results Panel (Scenario 02) — Results display

---

## Layout Structure

The app shell uses a 4-region layout: Header, Sidebar, Main Area (tabs + editor + results), and Status Bar.

### Desktop (>= 768px)

```
┌─────────────────────────────────────────────────────────┐
│  Header                [Logo]  [Theme] [Settings] [⌘]  │ 40px
├────────┬────────────────────────────────────────────────┤
│        │  Tab Bar   [Budget ×] [Invoice ×] [+]         │ 36px
│        ├─────────────────────────┬──┬──────────────────┤
│  Side  │                         │  │                  │
│  bar   │  Editor                 │ D│  Results         │
│        │  (CodeMirror 6)         │ iv│  Panel           │
│  240px │                         │  │                  │
│  (coll │                         │  │                  │
│  apsi  │                         │  │                  │
│  ble)  │                         │  │                  │
│        │                         │  │                  │
├────────┴─────────────────────────┴──┴──────────────────┤
│  Status Bar    [Ln 12, Col 8]  [Engine ●]  [Dark 🎨]  │ 24px
└─────────────────────────────────────────────────────────┘
```

### Tablet (768px — 1024px)

```
┌─────────────────────────────────────────┐
│  Header           [Logo] [Theme] [≡]   │ 40px
├─────────────────────────────────────────┤
│  Tab Bar   [Budget ×] [Invoice ×] [+]  │ 36px
├─────────────────────────┬──┬────────────┤
│                         │  │            │
│  Editor                 │ D│  Results   │
│  (CodeMirror 6)         │ iv│  Panel     │
│                         │  │            │
├─────────────────────────┴──┴────────────┤
│  Status Bar                             │ 24px
└─────────────────────────────────────────┘
Sidebar: overlay drawer via hamburger [≡]
```

### Mobile (< 768px)

```
┌─────────────────────────┐
│  Header   [Logo] [≡]   │ 44px (touch)
├─────────────────────────┤
│  Tab Bar (scrollable)   │ 36px
├─────────────────────────┤
│                         │
│  Editor                 │
│  (full width)           │
│                         │
│                         │
├─────────────────────────┤
│  Results Tray (toggle)  │ 48px collapsed / 40vh expanded
├─────────────────────────┤
│  Status Bar             │ 24px
└─────────────────────────┘
Sidebar: full-screen drawer
Results: bottom tray with drag handle
```

---

## Spacing

**Scale:** [Spacing Scale](../../../D-Design-System/00-design-system.md#spacing-scale)

| Property | Token | Pixels (proposed) |
|----------|-------|--------------------|
| Page padding (horizontal) | space-zero | 0px (panels fill edge-to-edge) |
| Header padding (horizontal) | space-md | 12px |
| Header padding (vertical) | space-xs | 6px |
| Sidebar width (default) | — | 240px |
| Sidebar min width | — | 180px |
| Sidebar max width | — | 400px |
| Divider width (sidebar ↔ editor) | — | 1px visible, 8px hit area |
| Divider width (editor ↔ results) | — | 1px visible, 8px hit area |
| Tab bar height | — | 36px |
| Tab padding (horizontal) | space-sm | 8px |
| Status bar height | — | 24px |
| Status bar padding (horizontal) | space-md | 12px |

---

## Typography

**Scale:** [Type Scale](../../../D-Design-System/00-design-system.md#type-scale)

| Element | Semantic | Size | Weight | Typeface |
|---------|----------|------|--------|----------|
| App title (header) | — | text-sm | 600 | system sans |
| Tab label | — | text-xs | 400 (normal), 500 (active) | system sans |
| Status bar text | — | text-3xs | 400 | system mono |
| Sidebar section title | H3 | text-2xs | 600 | system sans |
| Sidebar file name | — | text-xs | 400 | system sans |
| Editor content | — | text-md | 400 | system mono |
| Results value | — | text-md | 400 | system mono |

---

## Page Sections

### Section: Header

**OBJECT ID:** `shell-header`

| Property | Value |
|----------|-------|
| Purpose | App identity, global actions, theme quick-switch |
| Height | 40px (desktop/tablet), 44px (mobile — touch target) |
| Background | var(--bg) |
| Border | bottom 1px solid var(--border) |
| Layout | Horizontal: logo-left, actions-right |

#### Logo Group

**OBJECT ID:** `shell-header-logo`

| Property | Value |
|----------|-------|
| Content | CalcText icon + wordmark |
| Icon size | 20px × 20px |
| Wordmark | "CalcText" in text-sm, weight 600 |
| Gap | space-xs (6px) between icon and wordmark |
| Mobile | Wordmark hidden < 480px, icon only |

#### Header Actions

**OBJECT ID:** `shell-header-actions`

| Property | Value |
|----------|-------|
| Layout | Horizontal, space-xs gap |
| Items | Theme toggle, Settings button, Keyboard shortcuts (⌘) |
| Button size | 28px × 28px (icon buttons) |
| Icon size | 16px |
| Style | Ghost buttons — transparent bg, var(--text) icon, hover → var(--accent-bg) |

#### Theme Toggle (Header)

**OBJECT ID:** `shell-header-theme-toggle`

| Property | Value |
|----------|-------|
| Component | Icon button with dropdown |
| Icon | Sun (light), Moon (dark), Terminal (matrix), Palette (custom) |
| Click | Opens theme picker dropdown |
| Tooltip | "Switch theme (Ctrl+Shift+T)" |

#### ↕ `shell-header-v-space-zero` — Header sits flush against tab bar below

---

### Section: Sidebar

**OBJECT ID:** `shell-sidebar`

| Property | Value |
|----------|-------|
| Purpose | File navigation, document organization, templates |
| Width | 240px default, resizable (180–400px), collapsible to 0 |
| Background | var(--bg-secondary) |
| Border | right 1px solid var(--border) |
| Toggle | Cmd/Ctrl+B to show/hide |
| Resize | Drag right edge, cursor col-resize |
| Persistence | Width and visibility stored in localStorage |

#### Sidebar Sections

**OBJECT ID:** `shell-sidebar-sections`

| Section | Icon | Content |
|---------|------|---------|
| **Recent** | 🕐 | Last 5 opened documents, sorted by time |
| **Favorites** | ⭐ | User-pinned documents |
| **Files** | 📁 | Full folder tree with nested structure |
| **Templates** | 📋 | Pre-built starting points (Budget, Invoice, Unit Converter, Trip Planner, Blank) |

Each section is collapsible with a chevron toggle.

#### File Tree Item

**OBJECT ID:** `shell-sidebar-file-item`

| Property | Value |
|----------|-------|
| Height | 28px |
| Padding left | 12px + (depth × 16px) for nesting |
| Icon | 📄 file / 📁 folder (closed) / 📂 folder (open) |
| Label | File/folder name, text-xs, ellipsis on overflow |
| Hover | var(--accent-bg) background |
| Active | var(--accent-bg) + left 2px accent border |
| Right-click | Context menu: Rename, Delete, Duplicate, Move to folder, Add to favorites |
| Double-click | Opens document in new tab |
| Drag | Reorder within folder, drag between folders |

#### Sidebar Footer

**OBJECT ID:** `shell-sidebar-footer`

| Property | Value |
|----------|-------|
| Content | [+ New Document] button, [+ New Folder] button |
| Layout | Horizontal, full width, space-xs gap |
| Button style | Ghost, text-2xs, var(--text), hover → var(--accent) |
| Position | Sticky bottom of sidebar |
| Padding | space-sm |
| Border | top 1px solid var(--border) |

---

### Section: Tab Bar

**OBJECT ID:** `shell-tabbar`

| Property | Value |
|----------|-------|
| Purpose | Multi-document navigation, quick tab management |
| Height | 36px |
| Background | var(--bg-secondary) |
| Border | bottom 1px solid var(--border) |
| Layout | Horizontal scroll when tabs overflow |
| Position | Between header and editor area |

#### Tab Item

**OBJECT ID:** `shell-tabbar-tab`

| Property | Value |
|----------|-------|
| Min width | 100px |
| Max width | 200px |
| Padding | 0 space-sm (0 8px) |
| Height | 36px (fills bar) |
| Label | Document title, text-xs, ellipsis on overflow |
| Modified indicator | Dot (6px) before title when unsaved changes |
| Close button | × icon, 14px, visible on hover or active tab |
| Active state | var(--bg) background, no bottom border (connected to editor) |
| Inactive state | var(--bg-secondary), bottom border 1px solid var(--border) |
| Hover (inactive) | var(--bg-secondary) lightened slightly |
| Drag | Reorder tabs via drag-and-drop |
| Middle-click | Close tab |
| Double-click | Rename document inline |

#### New Tab Button

**OBJECT ID:** `shell-tabbar-new`

| Property | Value |
|----------|-------|
| Icon | + (16px) |
| Size | 36px × 36px (square, fills bar height) |
| Style | Ghost, var(--text), hover → var(--accent) |
| Click | Creates "Untitled" document and switches to it |
| Position | After last tab, before overflow |

#### Tab Overflow

**OBJECT ID:** `shell-tabbar-overflow`

| Property | Value |
|----------|-------|
| Trigger | When tabs exceed container width |
| Behavior | Horizontal scroll with mouse wheel or trackpad |
| Indicators | Fade gradient on edges when scrollable |
| Keyboard | Ctrl+Tab / Ctrl+Shift+Tab to cycle tabs |

---

### Section: Main Area

**OBJECT ID:** `shell-main`

| Property | Value |
|----------|-------|
| Purpose | Contains the active document's editor and results panel |
| Layout | Horizontal flex: editor (flex: 3) + divider + results (flex: 1) |
| Background | var(--bg) |
| Content | Delegates to Scenario 02 (Editor + Results Panel) |

#### Editor Pane

**OBJECT ID:** `shell-main-editor`

| Property | Value |
|----------|-------|
| Flex | 3 (default ~75%) |
| Min width | 300px |
| Content | CodeMirror 6 instance (see Scenario 02) |
| Overflow | Vertical scroll (editor handles internally) |

#### Pane Divider (Editor ↔ Results)

**OBJECT ID:** `shell-main-divider`

| Property | Value |
|----------|-------|
| Width | 1px visible line |
| Hit area | 8px (invisible padding for easy grabbing) |
| Cursor | col-resize |
| Color | var(--border), hover → var(--accent) |
| Transition | background 0.15s |
| Double-click | Reset to default 75/25 split |
| Persistence | Position stored in localStorage |

#### Results Pane

**OBJECT ID:** `shell-main-results`

| Property | Value |
|----------|-------|
| Flex | 1 (default ~25%) |
| Min width | 120px |
| Content | Results panel (see Scenario 02) |
| Scroll sync | Mirrors editor scroll position |

---

### Section: Status Bar

**OBJECT ID:** `shell-statusbar`

| Property | Value |
|----------|-------|
| Purpose | Contextual info: cursor position, engine status, theme indicator |
| Height | 24px |
| Background | var(--bg-secondary) |
| Border | top 1px solid var(--border) |
| Font | text-3xs, monospace |
| Color | var(--text) |
| Layout | Horizontal: left-info + right-info |

Full specification in [1.2 — Status Bar](../1.2-status-bar/1.2-status-bar.md).

---

## Page States

| State | When | Appearance | Actions |
|-------|------|------------|---------|
| **First Launch** | No localStorage data | Sidebar open with Templates section expanded. Single tab "Welcome" with demo calctext. Theme follows OS preference. | User can start typing, explore templates, or create new doc |
| **Returning User** | localStorage has documents | Restores: last open tabs, active tab, sidebar state, theme, divider positions | Resume exactly where they left off |
| **Empty Workspace** | All documents deleted | Editor shows subtle placeholder: "Create a new document or choose a template to get started" | + New Document button prominent, Templates section highlighted |
| **Engine Loading** | WASM initializing | Status bar shows "Engine loading..." with pulse animation. Editor is editable. Results show "—" | Editor works, results appear once engine is ready |
| **Offline** | No network | Subtle indicator in status bar. All features work (localStorage). Currency rates may be stale. | Full functionality, offline banner only if currency conversion attempted |

---

## Interactions & Keyboard Shortcuts

| Shortcut | Action |
|----------|--------|
| Cmd/Ctrl + B | Toggle sidebar |
| Cmd/Ctrl + N | New document |
| Cmd/Ctrl + W | Close active tab |
| Cmd/Ctrl + Tab | Next tab |
| Cmd/Ctrl + Shift + Tab | Previous tab |
| Cmd/Ctrl + 1–9 | Switch to tab N |
| Cmd/Ctrl + Shift + T | Open theme picker |
| Cmd/Ctrl + , | Open settings |
| Cmd/Ctrl + S | Force save (visual confirmation — auto-save is default) |

---

## Responsive Behavior

| Breakpoint | Layout Changes |
|------------|----------------|
| **>= 1024px** | Full 3-panel: sidebar + editor + results |
| **768–1023px** | Sidebar becomes overlay drawer (hamburger toggle). Editor + results remain side-by-side |
| **< 768px** | Single column. Sidebar = full-screen drawer. Results = bottom tray (collapsible). Tabs = horizontal scroll. Header = 44px (touch). |

### Mobile Results Tray

| Property | Value |
|----------|-------|
| Collapsed height | 48px (shows last result + drag handle) |
| Expanded height | 40vh |
| Drag handle | 32px × 4px pill, centered, var(--border) |
| Swipe up | Expand tray |
| Swipe down | Collapse tray |
| Tap collapsed | Expand tray |

### Mobile Sidebar Drawer

| Property | Value |
|----------|-------|
| Width | 85vw (max 320px) |
| Background | var(--bg) |
| Overlay | 50% black backdrop |
| Animation | Slide from left, 200ms ease-out |
| Close | Tap backdrop, swipe left, or X button |

---

## Theme Integration

The app shell's colors are entirely driven by CSS custom properties. Switching themes means swapping the property values on `:root`. No component changes needed.

| Theme | --bg | --bg-secondary | --text | --accent | Special |
|-------|------|----------------|--------|----------|---------|
| **Light** | #fff | #f8f9fa | #6b6375 | #6366f1 | — |
| **Dark** | #16171d | #1a1b23 | #9ca3af | #818cf8 | — |
| **Matrix** | #0a0a0a | #0f0f0f | #00ff41 | #00ff41 | Monospace everywhere. Subtle scanline overlay. Cursor blink green. |
| **Custom** | User-defined | User-defined | User-defined | User-defined | Accent color picker + base tone (warm/cool/neutral) |

Theme selection persisted in localStorage as `calctext-theme`.

---

## localStorage Schema

```typescript
interface CalcTextStorage {
  // Documents
  documents: Document[]
  folders: Folder[]
  activeTabId: string
  openTabIds: string[]

  // Layout
  sidebarWidth: number
  sidebarVisible: boolean
  dividerPosition: number  // percentage

  // Preferences
  theme: 'light' | 'dark' | 'matrix' | string  // string for custom
  customTheme?: ThemeTokens
  accentColor?: string

  // State
  lastOpenedAt: string  // ISO timestamp
}

interface Document {
  id: string
  title: string
  content: string
  folderId: string | null
  isFavorite: boolean
  createdAt: string
  updatedAt: string
}

interface Folder {
  id: string
  name: string
  parentId: string | null
  order: number
}
```

---

## Technical Notes

- **Cross-platform portability:** All layout patterns map to native equivalents. Sidebar → NavigationView (SwiftUI) / side_panel (iced). Tab bar → TabView. Status bar → standard OS status bar pattern.
- **Performance:** Only the active tab's CodeMirror instance should be in DOM. Inactive tabs store content in memory, restore on switch.
- **Auto-save:** Documents save to localStorage on every change (debounced 500ms). No explicit "save" needed, but Cmd+S provides visual confirmation.
- **Sidebar resize:** Use ResizeObserver + mouse events. Store width in localStorage. Minimum 180px, maximum 400px.
- **Tab management:** Maximum suggested tabs: 20. Beyond that, show "too many tabs" hint. No hard limit.

---

## Open Questions

| # | Question | Context | Status |
|---|----------|---------|--------|
| 1 | Should Matrix theme have a subtle CRT scanline effect? | Could be fun but might impact readability | 🔴 Open |
| 2 | Should we support tab groups / workspaces? | Multiple sets of tabs for different projects | 🔴 Open — defer to v2 |
| 3 | Max localStorage size for documents? | ~5MB browser limit. Need strategy for large collections. | 🟡 In Discussion — may need IndexedDB |

---

## Checklist

- [x] Page purpose clear
- [x] All Object IDs assigned
- [x] Layout structure defined (desktop, tablet, mobile)
- [x] Spacing tokens documented
- [x] Typography scale applied
- [x] States documented (first launch, returning, empty, loading, offline)
- [x] Keyboard shortcuts defined
- [x] Responsive breakpoints specified
- [x] Theme integration documented
- [x] localStorage schema defined
- [x] Cross-platform portability noted
- [x] Open questions captured

---

**Next Step:** → [Status Bar](../1.2-status-bar/1.2-status-bar.md)

---

_Created using Whiteport Design Studio (WDS) methodology_
