docs: add development guide and fix broken documentation links

cli/README.md

@@ -53,7 +53,7 @@ bun run test:tmux-poc
 # ✅ Works:  tmux send-keys -t session $'\e[200~hello\e[201~'
 ```
 
-See [tmux.knowledge.md](tmux.knowledge.md) for comprehensive tmux documentation and [src/__tests__/README.md](src/__tests__/README.md) for testing documentation.
+See [scripts/tmux/README.md](../scripts/tmux/README.md) and [docs/testing.md](../docs/testing.md) for comprehensive tmux documentation and testing guides.
 
 ## Build
 

cli/src/__tests__/README.md

@@ -165,7 +165,7 @@ await sleep(1000)
 
 ## tmux Testing
 
-**See [`../../tmux.knowledge.md`](../../tmux.knowledge.md) for comprehensive tmux documentation**, including:
+**See [`../../../scripts/tmux/README.md`](../../../scripts/tmux/README.md) and [`../../../docs/testing.md`](../../../docs/testing.md) for comprehensive tmux documentation**, including:
 
 - Why standard `send-keys` doesn't work (must use bracketed paste mode)
 - Helper functions for Bash and TypeScript

docs/development.md

@@ -0,0 +1,114 @@
+# Development Guide
+
+This guide covers local environment setup, monorepo architecture, development workflows, and testing practices for contributing to Freebuff.
+
+---
+
+## 📦 Monorepo Architecture
+
+Freebuff is structured as a TypeScript monorepo using Bun workspaces:
+
+| Workspace | Path | Purpose |
+|---|---|---|
+| **CLI** | `cli/` | Terminal User Interface (TUI) built with React and OpenTUI |
+| **SDK** | `sdk/` | `@codebuff/sdk` public package to orchestrate agents programmatically |
+| **Common** | `common/` | Shared types, Zod schemas, utilities, and tool definitions |
+| **Agents** | `agents/` | Agent definitions, prompts, and templates |
+| **Agent Runtime** | `packages/agent-runtime/` | Multi-agent execution loop, step orchestration, and tool execution |
+| **Code Map** | `packages/code-map/` | AST and Tree-sitter powered codebase indexing |
+| **LLM Providers** | `packages/llm-providers/` | Model adapters (DeepSeek, OpenAI, Anthropic, Gemini, MiMo, MiniMax) |
+| **Freebuff** | `freebuff/` | Freebuff distribution packaging and CLI build scripts |
+| **Tmux Scripts** | `scripts/tmux/` | Terminal emulation helpers for interactive CLI testing |
+
+---
+
+## 🛠️ Prerequisites
+
+- **[Bun](https://bun.sh)**: `v1.3.14` or higher (primary package manager and runtime)
+- **Node.js**: `v22+` (for compatibility with certain tooling)
+- **Git**: For version control
+- **tmux** *(optional)*: Required only for interactive CLI E2E testing (macOS: `brew install tmux`, Linux: `sudo apt-get install tmux`)
+
+---
+
+## 🚀 Getting Started
+
+### 1. Install Dependencies
+
+Install all workspace dependencies from the root:
+
+```bash
+bun install
+```
+
+### 2. Build the SDK
+
+The CLI and other packages depend on the built SDK:
+
+```bash
+bun run build:sdk
+```
+
+### 3. Run the CLI in Development Mode
+
+Start the terminal UI directly from source:
+
+```bash
+# Standard CLI dev mode
+bun start-cli
+
+# Or run Freebuff mode
+bun run dev:freebuff
+```
+
+### 4. Build the Freebuff Binary
+
+Compile the standalone Freebuff distribution binary:
+
+```bash
+bun run build:freebuff
+```
+
+---
+
+## 🧪 Testing
+
+Freebuff uses `bun:test` for fast, isolated unit and integration testing.
+
+### Running Unit Tests
+
+Run all unit tests across the repository:
+
+```bash
+bun test
+```
+
+Or run tests for a specific workspace:
+
+```bash
+# Test common utilities
+bun test common/src/
+
+# Test SDK
+bun test sdk/
+
+# Test CLI
+bun test cli/
+```
+
+### Interactive CLI Testing (tmux)
+
+For testing terminal rendering, bracketed paste mode, and keyboard navigation, Freebuff uses tmux-based session testing. See [`docs/testing.md`](./testing.md) and [`scripts/tmux/README.md`](../scripts/tmux/README.md) for full details.
+
+---
+
+## 📋 Code Conventions & Pre-PR Checklist
+
+Before opening a pull request, ensure the following checks pass:
+
+1. **Build the SDK**: `bun run build:sdk`
+2. **Run Unit Tests**: `bun test`
+3. **Validate Monorepo CI**: `bun run ci`
+4. **Clean Code**: Follow TypeScript strict typing, avoid `any`, and preserve existing documentation.
+
+For pull request submission guidelines and scoping rules, see the [Contributing Guide](../CONTRIBUTING.md).