# Frontend Architecture — Verstak GUI

## Tech Stack

- **Framework**: Svelte 4 (runes-free, compiler-only)
- **Build tool**: Vite 5
- **GUI shell**: Wails v2 (Go backend + WebKit frontend)
- **Language**: Plain JavaScript (no TypeScript in Svelte files — `lang="ts"` is NOT used)

## Source Structure

```
frontend/src/
  main.js                        # Entry: mounts App.svelte, global error handlers
  App.svelte                     # Root component: sidebar, header, modals, tab router
  FileTreeRow.svelte             # Sidebar tree node row
  TreeNode.svelte                # Recursive tree node
  lib/
    AppHeader.svelte             # Top bar with title, search, actions
    BrowserEvents.svelte         # Browser extension events panel
    CalendarPluginPage.svelte    # Plugin page host
    ConfirmModal.svelte          # Reusable confirm dialog
    FileBreadcrumbs.svelte       # File tab breadcrumb navigation
    FileIcon.svelte              # Icon resolver for file types
    FilePreviewModal.svelte      # File content preview modal
    FirstRun.svelte              # First-run wizard
    GlobalSearch.svelte          # Global search bar + results
    SettingsWindow.svelte        # Settings modal container
    Settings*.svelte             # Settings sub-sections (General, Sync, etc.)
    SyncStatus.svelte            # Sync status badge
    TemplateIcon.svelte          # Template type icon
    TodayScreen.svelte           # Today dashboard
    VaultRecovery.svelte         # Vault recovery wizard
    actionIcons.js               # SVG icon strings
    fileUtils.js                 # File type helpers (canPreview, isMarkdown, etc.)
    i18n/                        # Internationalization (en, ru)
    markdown/                    # Markdown rendering + internal links
    util/                        # Keyboard layout helper
    components/
      notes/
        MarkdownEditor.svelte    # Markdown textarea with toolbar
        MarkdownPreview.svelte   # Rendered markdown preview
        NoteEditorPanel.svelte   # Editor + preview layout, public API: insertText()
        InternalLinkPicker.svelte # Object picker for verstak:// links
        ObjectPickerModal.svelte  # Legacy object picker modal
```

## Role of App.svelte

`App.svelte` is the **root component**. It owns:

1. **Global UI state**: sidebar (system views, workspace tree), active tab, selected node/section
2. **Lifecycle**: startup checks (GetStartupStatus, VerstakVersion, ListWorkspaceTree), event listeners
3. **Top-level modals**: confirm, rename, import, worklog, inbox assign, link edit, settings, file preview
4. **Cross-cutting concerns**: navigation history (goBack, rememberNavigation), keyboard shortcuts, drag-and-drop orchestration, capture/inbox flow

App.svelte is **NOT** responsible for:
- Individual tab content (Overview, Notes, Files) — these are inlined but should be extracted
- Note editor internals — `NoteEditorPanel.svelte` + `MarkdownEditor.svelte` handle this
- Settings sections — each has its own `Settings*.svelte`

## State Ownership Rules

### App.svelte MUST own:
- `selectedSection`, `selectedNode`, `activeTab`
- `systemViews`, `workspaceTree`, `enabledTemplates`
- `noteEditor` (the note being edited), `noteViewMode`
- `showFirstRun`, `showRecovery`, `showSettings`, `loading`
- `startupStatus`, `startupChecked`
- Navigation state: `navHistory`, `restoringHistory`
- Trash browser state: `trashInfo`, `trashCount`, `trashSelectedIds`, `trashFolderId`, `trashFolderStack`
- Journal state: `journalRows`, `journalSummary`, filters
- Worklog modal state: `showWorklogModal`, `wlModal*`
- Inbox: `inboxNodes`, `localInboxNodes`, capture state
- Links: `links`
- Sync: `syncStatus`
- `error` (global error banner)

### App.svelte must NOT directly own (after extraction):
- Files tab internal state → `FilesTab.svelte`
- Notes tab list UI state → `NotesTab.svelte`
- Overview tab content → `OverviewTab.svelte`

## Component Communication

### Props (parent → child)
Data flows down via Svelte `export let prop`

### Events (child → parent)
Children dispatch events via `createEventDispatcher()`
- Suffix `:` in event names means handler in template: `on:openNote={handler}`, NOT call on mount
- All events should use `e.detail` to pass data

### Public API (bind:this)
Parent gets imperative handle via `bind:this={ref}` and calls:
- `ref.publicMethod(args)` — guard with optional chaining: `ref?.publicMethod?.(args)`
- Methods are exposed via `export function` in child component

## Services (Wails API)

All backend calls go through the `wailsCall()` helper in App.svelte:

```js
function wailsCall(method, ...args) {
  // Returns Promise, rejects with 'Wails not connected: <method>' if backend unavailable
}
```

Key backend methods:
- **Startup**: `GetStartupStatus`, `VerstakVersion`, `ListSystemViewsWithPlugins`, `ListWorkspaceTree`, `ListEnabledTemplates`
- **Nodes**: `GetNodeDetail`, `ListItems`, `ListWorkspaceChildren`, `CreateNodeFromTemplate`, `DeleteNode`, `MoveNode`, `RenameNode`
- **Notes**: `ListNotes`, `CreateNote`, `ReadNote`, `SaveNote`, `DeleteNote`, `RenameNote`
- **Files**: `ListFiles`, `DeleteFileOrFolder`, `CreateEmptyFile`, `DuplicateNode`, `OpenFile`, `OpenFolder`, `GetFileBase64`, `ReadFileText`, `PreviewImport`, `AddPathCopy`, `AddPathLink`
- **Worklog**: `ListWorklog`, `CreateWorklogFull`, `UpdateWorklogEntry`, `DeleteWorklogEntry`, `AcceptSuggestionFull/With`, `GetSuggestions`
- **Inbox**: `ListInboxNodes`, `Capture*WithContext`, `DeleteInboxNode`, `ResolveInboxNode`
- **Sync**: `SyncStatus`, `SyncNow`, `TrashCount`, `ListTrash`
- **Logging**: `FrontendLog(level, message, stack)`, `LogStartupStep(step, success, detail)`

## Logging & Diagnostics

### Frontend errors
- Global `window.addEventListener('error', ...)` catches uncaught exceptions
- Global `window.addEventListener('unhandledrejection', ...)` catches broken promises
- Both log to `console.error` and forward to `FrontendLog()` backend binding
- Fatal mount error: renders error message inline in `#app` div (blank window becomes diagnostic)

### Backend logs
- Application log file: `~/.local/state/verstak/logs/verstak.log` (Linux)
- Fallback: `~/.config/verstak/logs/verstak.log`
- Format: `[timestamp] [level] message`
- Go `log.Printf()` output goes to stderr (visible in dev console)

### Vault debug log
- `<vault>/.verstak/debug.log` — written by `WriteDebugLog` binding (existing feature)

## Refactor Rules

### After each extraction step:
1. `grep` App.svelte for state that moved to child — must be zero hits or documented exceptions
2. `npm run build` — must pass
3. `go test ./...` — must pass
4. Manual GUI check:
   - Window is not blank/white
   - Sidebar shows (system views + workspace tree)
   - No infinite "Загрузка..." on welcome screen
   - Clicking system sections works
   - Opening a case shows tabs

### Forbidden patterns:
- Child component state referenced directly in App.svelte after extraction
- `lang="ts"` in Svelte files (svelte-preprocess not installed)
- `[]string` passed directly to Wails bindings (must JSON-serialize)
- Modal without `role="dialog" aria-modal="true"` and Escape handler
- Buttons without `type="button"` in forms
- `resize: none` on textareas that should be resizable (use `resize: vertical`)

## Troubleshooting

### Blank window, no errors in terminal
1. Check browser DevTools console (F12 on Windows/Linux, Cmd+Alt+I on macOS)
2. In Wails dev mode: right-click → Inspect → Console
3. Look for `[Frontend Error]` messages
4. Check application log: `~/.local/state/verstak/logs/verstak.log`

### Stuck on "Загрузка..."
- `GetStartupStatus` likely failed or returned unexpected status
- Check network calls in DevTools Network tab
- Check backend log for startup errors

### Wails method not found
- Ensure method is registered in `bindings*.go` files
- Ensure method is exported (capitalized name)
- Ensure `wailsCall()` helper is used (not direct window access)

### Child component state moved but App still references old variable
- This causes a silent `undefined` reference or runtime crash
- Run `grep -n 'oldStateName' App.svelte` after each extraction
- Use `ref?.method?.()` for all public API calls on child components