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PinchChat/ARCHITECTURE.md

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Architecture

A quick map of the PinchChat codebase for contributors.

Tech Stack

Layer Tech
Framework React 19 + TypeScript
Build Vite
Styling Tailwind CSS v4 + CSS custom properties (theming)
Icons Lucide React
Markdown react-markdown + rehype-highlight + remark-gfm
State React hooks + contexts (no external state library)

Directory Layout

src/
├── App.tsx              # Root: login gate, layout, lazy-loads Chat
├── main.tsx             # Entry point, renders App inside ErrorBoundary
├── types.ts             # Shared TypeScript types (Session, Message, etc.)
├── components/          # React components (see below)
├── hooks/               # Custom React hooks
├── lib/                 # Pure utility modules (no React)
└── contexts/            # React contexts (theme, tool collapse state)

Key Components

Component Purpose
LoginScreen Gateway URL + token input, credential persistence
Chat Main chat view: messages, input, header, search, split-view
ChatMessage Single message renderer (user/assistant/system events)
ChatInput Message composer with syntax-highlighted textarea + markdown preview
Sidebar Session list with search, pin, drag-reorder, delete, split-view
Header Top bar: agent name/avatar, model badge, token bar, theme/language switchers
ToolCall Expandable tool call card with emoji badges, params, results
ThinkingBlock Collapsible reasoning/thinking content display
CodeBlock Syntax-highlighted code with copy button
ImageBlock Inline image with loading skeleton, error fallback, lightbox
MessageSearch Ctrl+F search overlay with result navigation
KeyboardShortcuts ? shortcut help dialog

Hooks

Hook Purpose
useGateway Core hook: WebSocket connection, message streaming, session management, sending. This is the brain.
useSecondarySession Split-view: manages a second session's messages independently
useLocale i18n: language state + t() translation function
useTheme Theme read/write from ThemeContext
useToolCollapse Global expand/collapse state for tool calls
useNotifications Browser notification permission + sound alerts for new messages

Data Flow

OpenClaw Gateway ←—WebSocket—→ useGateway hook
                                    │
                         ┌──────────┼──────────┐
                         ▼          ▼          ▼
                      Sidebar    Chat      Header
                    (sessions)  (messages)  (status)
  1. Connect: LoginScreen collects gateway URL + token → useGateway opens a WebSocket
  2. Sessions: Gateway pushes session list → stored in hook state → rendered in Sidebar
  3. Messages: On session select, hook requests history → streamed tokens arrive as delta events → accumulated into messages → rendered by ChatMessage
  4. Sending: ChatInput calls sendMessage() from the hook → serialized over WebSocket
  5. Tool calls: Arrive as structured blocks within assistant messages → rendered by ToolCall with collapsible params/results

Theming

Themes use CSS custom properties defined in ThemeContext. All components reference var(--pc-*) variables (via Tailwind utility classes like text-pc-text, bg-pc-elevated, etc.) rather than hardcoded colors.

Available themes: Dark (default), Light, OLED Black, System (follows OS preference).

Accent colors: Cyan, Violet, Emerald, Amber, Rose, Blue.

Bundle Strategy

Vite splits the build into chunks via manualChunks in vite.config.ts:

Chunk Contents
react-vendor React + ReactDOM
markdown react-markdown, remark/rehype plugins, highlight.js
icons lucide-react
ui @radix-ui primitives
index App code

Chat is lazy-loaded (React.lazy) so the markdown chunk only loads after login.

Gateway Protocol

PinchChat communicates with OpenClaw via a WebSocket protocol. Key message types:

  • Outbound: auth, subscribe, send, listSessions, loadHistory, deleteSession
  • Inbound: authenticated, sessions, history, delta (streaming tokens), message (complete), error

The protocol is implemented in src/lib/gateway.ts (low-level) and src/hooks/useGateway.ts (React integration).

PWA

A service worker (public/sw.js) caches static assets for offline shell support. The app is installable via the browser's "Add to Home Screen" prompt.