# Bdd > [UDS] Reference for Behavior-Driven Development: Gherkin Given-When-Then format and Three Amigos structure. Use when: writing or reviewing .feature scenarios, choosing ubiquitous language, running a discovery conversation about behaviour. Not for: executing the BDD lifecycle or RED/GREEN automation — that moved to the adoption layer (XSPEC-095); turning .feature files into E2E skeletons — use /e2e. Keywords: BDD, Gherkin, Given When Then, feature file, scenario, Three Amigos, 行為驅動開發, 場景, 特性檔. - Skill: `asiaostrich/bdd` (Agent Skill, multi-file: 4 files) - Install (CLI): `npx skillmds@latest add asiaostrich/bdd` - Raw SKILL.md: https://api.skillmd.com/api/skills/asiaostrich/bdd/raw - Safety review: pending - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Product & Planning - Author: AsiaOstrich (https://skillmd.com/u/asiaostrich) - Updated: 2026-09-10 - Page: https://skillmd.com/skills/asiaostrich/bdd --- # BDD Assistant | BDD 助手 > ⚠️ **Status: Reference（參考用，非可執行流程）** — BDD 生命週期協調（4 階段循環、Gherkin scaffolding、RED/GREEN 執行）已於 2026-04-28 移至 **adoption layer（XSPEC-095）**。此處保留 Gherkin 格式定義、Three Amigos 結構、BDD 循環圖供參考。 > Lifecycle orchestration has moved to the adoption layer (XSPEC-095); this document is **reference-only**. For enforced execution, use your adoption layer's toolchain. Guide through the Behavior-Driven Development (BDD) workflow using Given-When-Then format. 引導行為驅動開發（BDD）流程，使用 Given-When-Then 格式。 ## BDD Cycle | BDD 循環 ``` DISCOVERY ──► FORMULATION ──► AUTOMATION ──► LIVING DOCS ^ │ └────────────────────────────────────────────┘ ``` ## Workflow | 工作流程 > 📖 以下為流程的**參考結構**，非可執行步驟；自動化／強制執行請用 adoption layer 工具鏈（XSPEC-095）。 > The steps below are a **reference structure**, not an executable workflow. ### 1. DISCOVERY - Explore Behavior | 探索行為 Discuss with stakeholders, identify examples and edge cases, understand the "why". ### 2. FORMULATION - Write Scenarios | 制定場景 Write Gherkin scenarios using ubiquitous language, make them concrete and specific. ### 3. AUTOMATION - Implement Tests | 自動化測試 Implement step definitions, write minimal code to pass, follow TDD within automation. ### 4. LIVING DOCUMENTATION - Maintain | 活文件維護 Keep scenarios current, use as shared documentation, review with stakeholders. ## Gherkin Format | Gherkin 格式 ```gherkin Feature: User Login As a registered user I want to log in to my account So that I can access my dashboard Scenario: Successful login Given I am on the login page When I enter valid credentials Then I should see my dashboard ``` ## Three Amigos | 三劍客會議 | Role | Focus | 角色 | 關注點 | |------|-------|------|--------| | **Business** | What & Why | 業務 | 什麼和為什麼 | | **Development** | How | 開發 | 如何實現 | | **Testing** | What if | 測試 | 假設情況 | ## Usage | 使用方式 ``` /bdd - Start interactive BDD session | 啟動互動式 BDD 會話 /bdd "user can reset password" - BDD for specific feature | 針對特定功能 /bdd login-feature.feature - Work with existing feature file | 處理現有功能檔案 ``` ## Next Steps Guidance | 下一步引導 After `/bdd` completes, the AI assistant should suggest: > **BDD 場景已定義。建議下一步 / BDD scenarios defined. Suggested next steps:** > - 執行 `/tdd` 實作步驟定義 ⭐ **Recommended / 推薦** — Implement step definitions > - 執行 `/checkin` 品質關卡（若功能完成）— Quality gates (if feature complete) > - 與利害關係人審查場景確保業務正確性 — Review scenarios with stakeholders ## Reference | 參考 - [BDD Workflow Guide](./bdd-workflow.md) — Read it when running discovery, formulation and automation as a cycle. - [Gherkin Quick Reference Guide](./gherkin-guide.md) — Read it when writing Given/When/Then and you need the exact syntax. - Detailed guide: [guide.md](./guide.md) - Core standard: [behavior-driven-development.md](../../core/behavior-driven-development.md) ## AI Agent Behavior | AI 代理行為 > 完整的 AI 行為定義請參閱對應的命令文件：[`/bdd`](../commands/bdd.md#ai-agent-behavior--ai-代理行為) > > For complete AI agent behavior definition, see the corresponding command file: [`/bdd`](../commands/bdd.md#ai-agent-behavior--ai-代理行為)