refactor(tools): modularize CLI with urfave/cli/v2, externalise template metadata

- Split monolithic build-preview.go into modular packages:
  tools.go (entry), cli/ (list/create/delete/preview commands),
  config/ (JSON loading), preview/ (rendering engine, funcs, locale)
- Extract all template metadata into data/templates_config.json
  as single source of truth — no hardcoded template data in Go
- Replace hand-rolled CLI parsing with github.com/urfave/cli/v2
- Add sensible defaults for --folder (../themes) and --config
  (./data/templates_config.json) — most commands now run bare
- Add type-coercing gt/lt/ge/le template funcs for JSON float64
- Fix AppUrl to gitea.com matching official template convention
- rendered.js now exports __REGISTRY__ and __PARAMS__ alongside
  __RENDERED__ — preview/index.html reads all from single source
- Cross-validate all 11 template data contexts against official
  Gitea source (services/mailer/*.go + templates/mail/*.tmpl)
- Update all docs (README, AGENTS, CONTRIBUTING, 5 languages)
  to reflect new CLI workflow with create scaffolding command

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.gitignore

@@ -18,5 +18,5 @@ Desktop.ini
 *.zip
 *.tar.gz
 
-# Generated preview data (run: go run ./tools/build-preview.go)
+# Generated preview data (run: cd tools && go run . preview all)
 preview/rendered.js

AGENTS.md

@@ -7,15 +7,24 @@ A curated collection of email template themes (10 visual styles) for self-hosted
 ## Repository Layout
 
 ```
-themes/             # Template themes (5 styles, 11 .tmpl each = 55 source files)
+themes/             # Template themes (10 styles, 11 .tmpl each = 110 source files)
-  horizon/          #   Enterprise / Corporate
+  aurora/           #   Ethereal / Dreamlike
-  terminal/         #   Developers / Tech
-  ember/            #   Community / Open Source
   bloom/            #   Creative / Startup (glassmorphism)
+  ember/            #   Community / Open Source
   heritage/         #   Education / Research
-tools/              # Go build tooling
+  horizon/          #   Enterprise / Corporate
-  build-preview.go  # Pre-renders all templates into preview/rendered.js
+  ink/              #   Editorial / Publishing
-  go.mod            # Go module (stdlib only, zero dependencies)
+  mono/             #   Minimal / Swiss design
+  neon/             #   Cyberpunk / Gaming
+  terminal/         #   Developers / Tech
+  terra/            #   Nature / Sustainability
+tools/              # Go CLI tooling (modular, zero dependencies)
+  tools.go          #   Main entry point
+  cli/              #   CLI subcommands: list, create, delete, preview
+  config/           #   Config types and templates_config.json loading
+  data/             #   templates_config.json — single source of truth for template metadata
+  preview/          #   Template rendering engine (funcs, locale, engine)
+  go.mod            #   Go module (stdlib only, zero dependencies)
 preview/            # Browser-based live preview
   index.html        # SPA with style/template/client/viewport switching
   rendered.js       # Pre-rendered HTML (generated, committed for clone-and-preview)
@@ -32,30 +41,34 @@ docs/               # Multi-language documentation
 - Each style must have all 11 template types
 
 ### Adding a New Theme
-1. Create `themes/<name>/` with the full `mail/` directory structure
+1. Scaffold the new theme: `cd tools && go run . create <name>` — creates the full directory structure with placeholder `.tmpl` files for all 11 email types
 2. Write all 11 `.tmpl` files with unique visual design
-3. Run `go run ./tools/build-preview.go` to regenerate preview data
+3. Run `cd tools && go run . preview all` to regenerate preview data
-4. Add the theme to the `<select id="sel-theme">` in `preview/index.html`
+4. Update README.md style gallery table
-5. Update README.md style gallery table
 
 ### Preview System
 - `preview/index.html` loads `preview/rendered.js` (pre-rendered by Go) and displays in iframes
 - Supports theme switching, template type switching, client simulation (Modern/Gmail/Outlook/Raw), and viewport toggle (Desktop 1386x780 / Mobile 390x780)
-- Entries in `REGISTRY` and `PARAMS` objects must match the Go build script's template definitions
+- `REGISTRY` and `PARAMS` are auto-generated from `templates_config.json` by the build tool — no manual syncing needed
 
-### Build Script
+### Build Tool
-- `tools/build-preview.go` uses Go's native `html/template` package
+- `tools/tools.go` is the main entry point for the modular CLI
-- Defines mock data for each template type matching Gitea's actual data contexts
+- Subcommands: `list`, `create`, `delete`, `preview`
-- Post-processes favicon URLs for preview display
+- Template metadata lives in `tools/data/templates_config.json` — the single source of truth
-- Zero external dependencies (stdlib only)
+- `tools/config/` handles config loading and data flattening
+- `tools/preview/` implements the rendering engine (template funcs, locale, engine)
+- `tools/cli/` implements CLI subcommands using `github.com/urfave/cli/v2`
+- Uses Go's native `html/template` package for template rendering
 
 ## Commit Conventions
 - `style(name):` — template changes for a specific theme
 - `preview:` — preview tooling changes
-- `tools:` — Go build script changes
+- `tools:` — Go CLI/build tooling changes
 - `docs:` — documentation and translations
 - `fix:` — bug fixes
 - `project:` — README, LICENSE, AGENTS.md, meta
+- `refactor:` — code restructuring (e.g. modularization)
+- `chore:` — maintenance (config updates, build scripts)
 
 ## Constraints
 - No JavaScript framework dependencies — preview is vanilla JS

CONTRIBUTING.md

@@ -8,12 +8,10 @@ Thanks for your interest in contributing! This project aims to provide a diverse
 
 ### Adding a New Style
 
-1. Create the style directory: `themes/<your-style-name>/`
+1. Scaffold the new style: `cd tools && go run . create <your-style-name>` — this creates the directory structure with placeholder `.tmpl` files for all 11 email types
-2. Copy the directory structure from an existing style
+2. Edit each `.tmpl` file in `themes/<your-style-name>/` with your unique visual design
-3. Implement all 11 `.tmpl` files with your unique visual design
+3. Regenerate the preview: `cd tools && go run . preview all` — the build script auto-discovers all theme directories under `themes/` and generates the theme selector dynamically
-4. Regenerate preview data: `go run ./tools/build-preview.go` — the build script auto-discovers all theme directories under `themes/`
+4. Submit a PR with screenshots of rendered emails
-5. Add your theme as an `<option>` in `<select id="sel-theme">` in `preview/index.html`
-6. Submit a PR with screenshots of rendered emails
 
 ### Style Guidelines
 
@@ -31,7 +29,7 @@ If a template doesn't render correctly:
 1. Check that all referenced Go template variables exist — compare against the Gitea source mail templates
 2. Verify translation keys match Gitea's locale files
 3. Confirm `.DisplayName` isn't used in templates that lack it
-4. Regenerate the preview: `go run ./tools/build-preview.go`
+4. Regenerate the preview: `cd tools && go run . preview all`
 5. Open an issue with: the style name, which email type, and the error or unexpected output
 
 ### Documentation Improvements
@@ -53,10 +51,10 @@ No build tools or dependencies are needed — these are raw Go HTML templates.
 ### Regenerating Previews
 
 ```bash
-go run ./tools/build-preview.go
+cd tools && go run . preview all
 ```
 
-This renders all templates (themes auto-discovered from the themes/ directory) using Go's native `html/template` package and writes the output to `preview/rendered.js`.
+This renders all templates (themes auto-discovered from the themes/ directory) using Go's native `html/template` package and writes the output to `preview/rendered.js`. The `--folder` and `--config` flags default to `../themes` and `./data/templates_config.json` respectively — override them only when using a custom layout.
 
 ### Integration Testing
 

README.md

@@ -85,16 +85,16 @@ A live preview tool is included to browse all styles and email types without dep
 First, generate the preview data (requires Go):
 
 ```bash
-go run ./tools/build-preview.go
+cd tools && go run . preview all
 ```
 
 Then open `preview/index.html` directly in a browser. No server required.
 
-> `preview/rendered.js` is generated and git-ignored. Re-run the command after modifying templates.
+> `preview/rendered.js` is generated and git-ignored. Re-run `cd tools && go run . preview all` after modifying templates. Use `cd tools && go run .` to see all commands (list, create, delete, preview). Most flags have sensible defaults — just `go run . create <name>` or `go run . preview all` works out of the box.
 
 ### Features
 
-- Theme switcher — toggle between all 5 visual styles
+- Theme switcher — toggle between all 10 visual styles
 - Template switcher — browse all 11 email types
 - Client simulation — Modern, Gmail (no `<style>`), Outlook Desktop, Raw source
 - Viewport toggle — Desktop (1386x780) / Mobile (390x780)
@@ -112,8 +112,12 @@ gitea-mail-templates/
 ├── preview/              # Live preview SPA
 │   ├── index.html        # Style/template/client/viewport switcher
 │   └── rendered.js       # Pre-rendered templates (generated by tools/)
-├── tools/                # Build tooling
+├── tools/                # Modular CLI tooling
-│   ├── build-preview.go  # Go build script — renders all templates
+│   ├── tools.go          #   Main entry point
+│   ├── cli/              #   CLI subcommands (list, create, delete, preview)
+│   ├── config/           #   Config types and templates_config.json loading
+│   ├── data/             #   templates_config.json — single source of truth
+│   ├── preview/          #   Template rendering engine
 │   └── go.mod
 ├── docs/                 # Multi-language documentation
 ├── AGENTS.md             # AI agent guidance

docs/CONTRIBUTING.ja.md

@@ -4,12 +4,10 @@
 
 ### 新しいスタイルの追加
 
-1. スタイルディレクトリを作成: `themes/<style-name>/`
+1. ツールでスキャフォールド: `cd tools && go run . create <style-name>` — 全11種類のメールタイプ用のプレースホルダ `.tmpl` ファイルを含む完全なディレクトリ構造を作成します
-2. 既存スタイルからディレクトリ構造をコピー
+2. `themes/<style-name>/` 内の各 `.tmpl` ファイルを独自デザインで編集
-3. 11個の `.tmpl` ファイルを独自デザインで実装
+3. プレビューを再生成: `cd tools && go run . preview all`（ビルドスクリプトが `themes/` 以下の全テーマを自動検出し、テーマセレクターも自動生成されます）
-4. プレビューを再生成: `go run ./tools/build-preview.go`（ビルドスクリプトが `themes/` 以下の全テーマを自動検出します）
+4. スクリーンショット付きで PR を提出
-5. `preview/index.html` の `<select id="sel-theme">` に追加
-6. スクリーンショット付きで PR を提出
 
 ### スタイルガイドライン
 
@@ -25,7 +23,7 @@
 1. Go 変数が正しいか確認
 2. 翻訳キーが Gitea ロケールと一致するか確認
 3. `.DisplayName` が誤用されていないか確認
-4. プレビューを再生成: `go run ./tools/build-preview.go`
+4. プレビューを再生成: `cd tools && go run . preview all`
 5. スタイル名とメールタイプを明記して issue を作成
 
 ---
@@ -34,7 +32,7 @@
 
 ### ローカルプレビュー
 
-1. データを生成: `go run ./tools/build-preview.go`
+1. データを生成: `cd tools && go run . preview all`
 2. `preview/index.html` をブラウザで開く
 3. Modern, Gmail, Outlook, Raw source を切り替えて確認
 

docs/CONTRIBUTING.ko.md

@@ -4,12 +4,10 @@
 
 ### 새 스타일 추가하기
 
-1. 스타일 디렉토리 생성: `themes/<style-name>/`
+1. 도구로 스캐폴드: `cd tools && go run . create <style-name>` — 11개 이메일 유형 모두에 대한 플레이스홀더 `.tmpl` 파일이 포함된 완전한 디렉토리 구조를 생성합니다
-2. 기존 스타일에서 디렉토리 구조 복사
+2. `themes/<style-name>/`에서 각 `.tmpl` 파일을 고유한 디자인으로 편집
-3. 11개 `.tmpl` 파일을 고유한 디자인으로 구현
+3. 프리뷰 재생성: `cd tools && go run . preview all` (빌드 스크립트가 `themes/` 아래의 모든 테마 디렉토리를 자동으로 찾고 테마 선택기도 자동 생성합니다)
-4. 프리뷰 재생성: `go run ./tools/build-preview.go` (빌드 스크립트가 `themes/` 아래의 모든 테마 디렉토리를 자동으로 찾습니다)
+4. 스크린샷과 함께 PR 제출
-5. `preview/index.html`의 `<select id="sel-theme">`에 추가
-6. 스크린샷과 함께 PR 제출
 
 ### 스타일 가이드라인
 
@@ -25,7 +23,7 @@
 1. Go 변수가 올바른지 확인
 2. 번역 키가 Gitea 로케일과 일치하는지 확인
 3. `.DisplayName`이 오용되지 않았는지 확인
-4. 프리뷰 재생성: `go run ./tools/build-preview.go`
+4. 프리뷰 재생성: `cd tools && go run . preview all`
 5. 스타일 이름과 메일 유형을 명시하여 이슈 생성
 
 ---
@@ -34,7 +32,7 @@
 
 ### 로컬 프리뷰
 
-1. 데이터 생성: `go run ./tools/build-preview.go`
+1. 데이터 생성: `cd tools && go run . preview all`
 2. `preview/index.html`을 브라우저에서 열기
 3. Modern, Gmail, Outlook, Raw source 모드 전환 확인
 

docs/CONTRIBUTING.ru.md

@@ -4,12 +4,10 @@
 
 ### Добавление нового стиля
 
-1. Создайте директорию стиля: `themes/<имя-стиля>/`
+1. Создайте каркас через инструмент: `cd tools && go run . create <имя-стиля>` — создаёт полную структуру директорий с файлами-заготовками `.tmpl` для всех 11 типов писем
-2. Скопируйте структуру из существующего стиля
+2. Отредактируйте каждый `.tmpl` файл в `themes/<имя-стиля>/` с вашим уникальным дизайном
-3. Реализуйте все 11 `.tmpl` файлов с уникальным дизайном
+3. Перегенерируйте превью: `cd tools && go run . preview all` (скрипт автоматически находит все темы в `themes/` и динамически генерирует селектор тем)
-4. Перегенерируйте превью: `go run ./tools/build-preview.go` (скрипт автоматически находит все темы в `themes/`)
+4. Отправьте PR со скриншотами
-5. Добавьте тему в `<select id="sel-theme">` в `preview/index.html`
-6. Отправьте PR со скриншотами
 
 ### Рекомендации по стилю
 
@@ -25,7 +23,7 @@
 1. Проверьте переменные Go в шаблонах
 2. Сверьте ключи перевода с локалью Gitea
 3. Убедитесь что `.DisplayName` не используется где не надо
-4. Перегенерируйте превью: `go run ./tools/build-preview.go`
+4. Перегенерируйте превью: `cd tools && go run . preview all`
 5. Создайте issue с указанием стиля и типа письма
 
 ---
@@ -34,7 +32,7 @@
 
 ### Локальный предпросмотр
 
-1. Сгенерируйте данные: `go run ./tools/build-preview.go`
+1. Сгенерируйте данные: `cd tools && go run . preview all`
 2. Откройте `preview/index.html` в браузере
 3. Переключайте Modern, Gmail, Outlook, Raw source для проверки
 

docs/CONTRIBUTING.zh-CN.md

@@ -4,12 +4,10 @@
 
 ### 添加新风格
 
-1. 创建风格目录：`themes/<风格名称>/`
+1. 使用工具脚手架：`cd tools && go run . create <风格名称>` — 这会创建完整的目录结构和全部 11 种邮件类型的占位 `.tmpl` 文件
-2. 从现有风格复制目录结构
+2. 在 `themes/<风格名称>/` 中编写每个 `.tmpl` 文件，应用独特的视觉设计
-3. 用独特的视觉设计实现全部 11 个 `.tmpl` 文件
+3. 重新生成预览：`cd tools && go run . preview all`（构建脚本会自动发现 `themes/` 下的所有主题目录并动态生成主题选择器）
-4. 重新生成预览：`go run ./tools/build-preview.go`（构建脚本会自动发现 `themes/` 下的所有主题目录）
+4. 提交包含截图渲染效果的 PR
-5. 在 `preview/index.html` 的 `<select id="sel-theme">` 中添加选项
-6. 提交包含截图渲染效果的 PR
 
 ### 风格指南
 
@@ -25,7 +23,7 @@
 1. 检查引用的 Go 模板变量是否存在
 2. 验证翻译键是否与 Gitea 语言文件匹配
 3. 确认 `.DisplayName` 未在不支持的模板中使用
-4. 重新生成预览：`go run ./tools/build-preview.go`
+4. 重新生成预览：`cd tools && go run . preview all`
 5. 提交 issue，注明风格名称、邮件类型及错误描述
 
 ### 改进文档
@@ -40,7 +38,7 @@
 
 ### 本地预览
 
-1. 先生成预览数据：`go run ./tools/build-preview.go`
+1. 先生成预览数据：`cd tools && go run . preview all`
 2. 在浏览器中打开 `preview/index.html`
 3. 在 Modern、Gmail、Outlook、Raw source 模式间切换验证效果
 

docs/CONTRIBUTING.zh-TW.md

@@ -4,12 +4,10 @@
 
 ### 新增風格
 
-1. 建立風格目錄：`themes/<風格名稱>/`
+1. 使用工具腳手架：`cd tools && go run . create <風格名稱>` — 這會建立完整的目錄結構和全部 11 種郵件類型的佔位 `.tmpl` 檔案
-2. 從現有風格複製目錄結構
+2. 在 `themes/<風格名稱>/` 中編寫每個 `.tmpl` 檔案，套用獨特的視覺設計
-3. 以獨特的視覺設計實作全部 11 個 `.tmpl` 檔案
+3. 重新產生預覽：`cd tools && go run . preview all`（建置腳本會自動發現 `themes/` 下的所有主題目錄並動態生成主題選擇器）
-4. 重新產生預覽：`go run ./tools/build-preview.go`（建置腳本會自動發現 `themes/` 下的所有主題目錄）
+4. 提交包含螢幕截圖的 PR
-5. 在 `preview/index.html` 的 `<select id="sel-theme">` 中新增選項
-6. 提交包含螢幕截圖的 PR
 
 ### 風格指南
 
@@ -25,7 +23,7 @@
 1. 檢查引用的 Go 模板變數是否存在
 2. 驗證翻譯鍵是否與 Gitea 語系檔案相符
 3. 確認 `.DisplayName` 未在不支援的模板中使用
-4. 重新產生預覽：`go run ./tools/build-preview.go`
+4. 重新產生預覽：`cd tools && go run . preview all`
 5. 提交 issue，註明風格名稱、郵件類型及錯誤描述
 
 ### 改善文件
@@ -40,7 +38,7 @@
 
 ### 本機預覽
 
-1. 先生成預覽資料：`go run ./tools/build-preview.go`
+1. 先生成預覽資料：`cd tools && go run . preview all`
 2. 在瀏覽器中開啟 `preview/index.html`
 3. 在 Modern、Gmail、Outlook、Raw source 模式間切換驗證效果
 

docs/README.ja.md

@@ -37,7 +37,7 @@ systemctl restart gitea
 ## プレビュー
 
 ```bash
-go run ./tools/build-preview.go
+cd tools && go run . preview all
 ```
 その後 `preview/index.html` を開く。
 

docs/README.ko.md

@@ -37,7 +37,7 @@ systemctl restart gitea
 ## 프리뷰
 
 ```bash
-go run ./tools/build-preview.go
+cd tools && go run . preview all
 ```
 그런 다음 `preview/index.html` 열기.
 

docs/README.ru.md

@@ -37,7 +37,7 @@ systemctl restart gitea
 ## Предпросмотр
 
 ```bash
-go run ./tools/build-preview.go
+cd tools && go run . preview all
 ```
 Затем откройте `preview/index.html`.
 

docs/README.zh-CN.md

@@ -51,7 +51,7 @@ systemctl restart gitea
 ## 预览
 
 ```bash
-go run ./tools/build-preview.go
+cd tools && go run . preview all
 ```
 然后打开 `preview/index.html`。
 

docs/README.zh-TW.md

@@ -51,7 +51,7 @@ systemctl restart gitea
 ## 預覽
 
 ```bash
-go run ./tools/build-preview.go
+cd tools && go run . preview all
 ```
 然後開啟 `preview/index.html`。
 

docs/images/README.md

@@ -11,7 +11,7 @@ neon.png       mono.png        terra.png    ink.png      aurora.png
 
 ## How to Capture
 
-1. Run `go run ./tools/build-preview.go` from the project root
+1. Run `cd tools && go run . preview all` from the project root
 2. Open `preview/index.html` in a browser
 3. For each style, select the "Activate Account" template and "Modern" client mode
 4. Take a screenshot of the rendered email (600px width recommended)

preview/index.html

@@ -56,6 +56,7 @@ body{font-family:system-ui,-apple-system,sans-serif;background:var(--bg);color:v
 #panel .badge{display:inline-block;font-size:9px;padding:1px 6px;border-radius:3px;font-weight:600;letter-spacing:.2px;white-space:nowrap}
 .badge-req{background:rgba(52,211,153,.12);color:var(--green)}
 .badge-opt{background:rgba(107,125,153,.1);color:var(--muted)}
+#panel .stat{font-size:10px;color:var(--muted);margin-top:6px}
 
 // ── Client indicators ──
 #panel .indicators{display:flex;flex-wrap:wrap;gap:4px 12px}
@@ -81,16 +82,7 @@ body{font-family:system-ui,-apple-system,sans-serif;background:var(--bg);color:v
   <span class="brand">Gitea Mail Templates <span>Preview</span></span>
   <span class="sep"></span>
   <label>Theme</label>
-  <select id="sel-theme" onchange="switchTheme(this.value)">
+  <select id="sel-theme" onchange="switchTheme(this.value)"></select>
-    <option value="horizon">Horizon</option><option value="terminal">Terminal</option>
-    <option value="ember">Ember</option><option value="bloom">Bloom</option>
-    <option value="heritage">Heritage</option>
-    <option value="neon">Neon</option>
-    <option value="mono">Mono</option>
-    <option value="terra">Terra</option>
-    <option value="ink">Ink</option>
-    <option value="aurora">Aurora</option>
-  </select>
   <span class="sep"></span>
   <label>Template</label>
   <select id="sel-template" onchange="switchTemplate(this.value)"></select>
@@ -130,6 +122,7 @@ body{font-family:system-ui,-apple-system,sans-serif;background:var(--bg);color:v
         <div class="label">Description</div>
         <div class="value" id="panel-desc" style="font-size:11px;line-height:1.5">-</div>
       </div>
+      <div class="stat" id="panel-stats"></div>
     </section>
     <section style="flex:1;overflow-y:auto">
       <h3>Parameters</h3>
@@ -149,44 +142,12 @@ body{font-family:system-ui,-apple-system,sans-serif;background:var(--bg);color:v
 <script src="rendered.js"></script>
 <script>
 //
-// Template registry — mirrors the Go build script definitions
+// State — REGISTRY and PARAMS are loaded from rendered.js (single source of truth)
 //
-const REGISTRY = {
+const state = { theme:'', template:'', client:'modern', viewport:'desktop' };
-  activate:        {name:'Activate Account',       path:'mail/user/auth/activate.tmpl',         desc:'Account activation — sent when a new user registers.'},
+let REGISTRY = {};
-  activate_email:  {name:'Activate Email',         path:'mail/user/auth/activate_email.tmpl',   desc:'Email address verification — sent when adding or changing an email address.'},
+let PARAMS = {};
-  register_notify: {name:'Register Notify',        path:'mail/user/auth/register_notify.tmpl',  desc:'Registration notification — confirms successful account registration.'},
+let rendered = null; // window.__RENDERED__
-  reset_passwd:    {name:'Reset Password',         path:'mail/user/auth/reset_passwd.tmpl',     desc:'Password reset — sent when user requests a password reset link.'},
-  team_invite:     {name:'Team Invite',            path:'mail/org/team_invite.tmpl',            desc:'Team invitation — sent when a user is invited to join an organization team.'},
-  collaborator:    {name:'Collaborator Added',     path:'mail/repo/collaborator.tmpl',          desc:'Collaborator added — sent when a user is added as a repository collaborator.'},
-  transfer:        {name:'Repository Transfer',    path:'mail/repo/transfer.tmpl',              desc:'Repository transfer — sent when repository ownership is transferred.'},
-  release:         {name:'New Release',            path:'mail/repo/release.tmpl',               desc:'New release — sent when a new release is published.'},
-  workflow_run:    {name:'Workflow Run',           path:'mail/repo/actions/workflow_run.tmpl',  desc:'Workflow run — sent when a CI/CD workflow completes.'},
-  assigned:        {name:'Issue Assigned',         path:'mail/repo/issue/assigned.tmpl',        desc:'Issue/PR assigned — sent when an issue or pull request is assigned.'},
-  default:         {name:'Issue Update',           path:'mail/repo/issue/default.tmpl',         desc:'Issue/PR update — comments, mentions, reviews, merges, and other activity.'}
-};
-
-//
-// Parameter definitions (informational only — rendering is done by Go)
-//
-const PARAMS = {
-  activate:        {'DisplayName':'Alex Johnson','Code':'activation-code-abc123','ActiveCodeLives':'24 hours','AppName':'Gitea','AppUrl':'https://about.gitea.com'},
-  activate_email:  {'DisplayName':'Alex Johnson','Code':'verify-code-xyz789','Email':'alex@example.com','ActiveCodeLives':'24 hours','AppName':'Gitea','AppUrl':'https://about.gitea.com'},
-  register_notify: {'DisplayName':'Alex Johnson','Username':'alexj','AppName':'Gitea','AppUrl':'https://about.gitea.com'},
-  reset_passwd:    {'DisplayName':'Alex Johnson','Code':'reset-token-abc123','ResetPwdCodeLives':'3 hours','AppName':'Gitea','AppUrl':'https://about.gitea.com'},
-  team_invite:     {'AppName':'Gitea','AppUrl':'https://about.gitea.com','Inviter.DisplayName':'Sarah Chen','Team.Name':'Core Developers','Organization.DisplayName':'Acme Corp','InviteURL':'...invite?token=abc','Invite.Email':'alex@example.com'},
-  collaborator:    {'AppName':'Gitea','AppUrl':'https://about.gitea.com','Subject':'Collaborator Added','Link':'.../repo/project','RepoName':'acme/project'},
-  transfer:        {'AppName':'Gitea','AppUrl':'https://about.gitea.com','Subject':'Repository Transfer','Link':'.../transferred-project','Repo':'acme/transferred-project'},
-  release:         {'AppName':'Gitea','AppUrl':'https://about.gitea.com','Subject':'New Release v2.0.0','Link':'.../repo/project/releases/tag/v2.0.0','Release.Publisher.Name':'Sarah Chen','Release.TagName':'v2.0.0','Release.Title':'Version 2.0','Release.HTMLURL':'.../releases/tag/v2.0.0','Release.Repo.HTMLURL':'.../repo/project','Release.Repo.FullName':'acme/project','Release.RenderedNote':'<p>Major new features...</p>','DisableDownloadSourceArchives':'false','Release.Attachments':'[]'},
-  workflow_run:    {'AppName':'Gitea','AppUrl':'https://about.gitea.com','Subject':'Workflow Run: CI','RunStatusText':'All jobs passed','Repo.FullName':'acme/project','Run.WorkflowID':'ci.yml','Run.HTMLURL':'.../actions/runs/42','Jobs':'[3 items]'},
-  assigned:        {'AppName':'Gitea','AppUrl':'https://about.gitea.com','Subject':'Issue #42 Assigned','Link':'.../repo/project/issues/42','Doer.Name':'Sarah Chen','IsPull':'false','Issue.Index':'42','Issue.Repo.HTMLURL':'.../repo/project','Issue.Repo.FullName':'acme/project'},
-  default:         {'AppName':'Gitea','AppUrl':'https://about.gitea.com','Subject':'Re: Issue #42','Link':'.../repo/project/issues/42','ActionName':'comment','Doer.Name':'Sarah Chen','Body':'This is a comment on the issue...','CanReply':'true','IsMention':'false','IsPull':'false','Issue.Index':'42','Issue.PullRequest.BaseBranch':'main','Comment.Commits':'[]','Comment.IsForcePush':'false','ReviewComments':'[]'}
-};
-
-//
-// State
-//
-const state = { theme:'horizon', template:'activate', client:'modern', viewport:'desktop' };
-let rendered = null; // loaded from rendered.js via <script> tag
 
 //
 // Client transforms
@@ -240,18 +201,31 @@ function render() {
 // Panel updates
 //
 function updatePanel() {
-  const t = REGISTRY[state.template];
+  const r = REGISTRY[state.template];
-  document.getElementById('panel-name').textContent = t.name;
+  document.getElementById('panel-name').textContent = r ? r.name : state.template;
-  document.getElementById('panel-desc').textContent = t.desc;
+  document.getElementById('panel-desc').textContent = r ? r.desc : '';
-  document.getElementById('panel-path').textContent = 'themes/'+state.theme+'/'+t.path;
+  document.getElementById('panel-path').textContent = r ? 'themes/'+state.theme+'/'+r.path : '-';
 
-  const p = PARAMS[state.template];
+  // Template stats
+  const themes = rendered ? Object.keys(rendered).length : 0;
+  let totalTemplates = 0, totalFailed = 0;
+  if (rendered && rendered[state.theme]) {
+    const themeData = rendered[state.theme];
+    totalTemplates = Object.keys(themeData).length;
+    for (const v of Object.values(themeData)) {
+      if (v.startsWith('<p style=\'color:red\'')) totalFailed++;
+    }
+  }
+  document.getElementById('panel-stats').textContent =
+    themes + ' themes loaded · ' + totalTemplates + ' templates (' + (totalTemplates - totalFailed) + ' ok, ' + totalFailed + ' failed)';
+
+  const p = PARAMS[state.template] || {};
   let rows = '';
   for(const [k,v] of Object.entries(p)){
     const isReq = !k.includes('RenderedNote') && !k.includes('Attachments') && !k.includes('DisableDownload') && !k.includes('IsMention') && !k.includes('IsPull') && !k.includes('IsForcePush') && !k.includes('ReviewComments') && !k.includes('Commits') && !k.includes('BaseBranch');
     rows += '<tr><td>.'+k+'</td><td>'+String(v)+'</td><td><span class="badge '+(isReq?'badge-req':'badge-opt')+'">'+(isReq?'required':'optional')+'</span></td></tr>';
   }
-  document.getElementById('panel-params').innerHTML = rows;
+  document.getElementById('panel-params').innerHTML = rows || '<tr><td colspan="3" style="color:var(--muted)">-</td></tr>';
 
   // Client simulation indicators
   const c=state.client,
@@ -292,18 +266,40 @@ document.addEventListener('keydown',e=>{
 });
 
 //
-// Init
+// Init — load everything from rendered.js (single source of truth)
 //
 (function(){
-  const sel=document.getElementById('sel-template');
+  // Load REGISTRY and PARAMS from rendered.js
-  for(const[id,t]of Object.entries(REGISTRY)){
+  if(window.__REGISTRY__) REGISTRY = window.__REGISTRY__;
-    const o=document.createElement('option');o.value=id;o.textContent=t.name;sel.appendChild(o);
+  if(window.__PARAMS__)   PARAMS   = window.__PARAMS__;
-  }
+
   if(window.__RENDERED__){
-    rendered=window.__RENDERED__;
+    rendered = window.__RENDERED__;
+
+    // Populate theme selector from rendered data
+    const themeKeys = Object.keys(rendered).sort();
+    const selTheme = document.getElementById('sel-theme');
+    themeKeys.forEach(t => {
+      const o = document.createElement('option');
+      o.value = t;
+      o.textContent = t.charAt(0).toUpperCase() + t.slice(1);
+      selTheme.appendChild(o);
+    });
+    state.theme = themeKeys[0] || '';
+
+    // Populate template selector from REGISTRY
+    const selTpl = document.getElementById('sel-template');
+    for(const [id, t] of Object.entries(REGISTRY)){
+      const o = document.createElement('option');
+      o.value = id;
+      o.textContent = t.name;
+      selTpl.appendChild(o);
+    }
+    state.template = Object.keys(REGISTRY)[0] || '';
+
     document.getElementById('loading').style.display='none';
-  }else{
+  } else {
-    document.getElementById('loading').innerHTML='<span style="color:var(--red)">rendered.js not found</span><small style="color:var(--muted);margin-top:8px">Run: cd tools && go run build-preview.go</small>';
+    document.getElementById('loading').innerHTML = '<span style="color:var(--red)">rendered.js not found</span><small style="color:var(--muted);margin-top:8px">Run: cd tools && go run . preview all</small>';
   }
   render();
 })();

tools/build-preview.go

@@ -1,399 +0,0 @@
-package main
-
-import (
-	"encoding/json"
-	"fmt"
-	"html/template"
-	"log"
-	"net/url"
-	"os"
-	"path/filepath"
-	"strings"
-)
-
-// TemplateFuncs maps Gitea's built-in template functions
-var TemplateFuncs = template.FuncMap{
-	"AppUrl":              func() string { return "https://about.gitea.com/" },
-	"AppName":             func() string { return "Gitea" },
-	"DotEscape":           func(s string) template.HTML { return template.HTML(template.HTMLEscapeString(s)) },
-	"QueryEscape":         url.QueryEscape,
-	"ShortSha":            ShortSha,
-	"PathEscapeSegments":  PathEscapeSegments,
-	"FileSize":            FileSize,
-	"HTMLFormat":          HTMLFormat,
-	"Dict":                Dict,
-}
-
-func ShortSha(s string) string {
-	if len(s) > 10 { return s[:10] }
-	return s
-}
-
-func PathEscapeSegments(s string) string {
-	parts := strings.Split(s, "/")
-	for i, p := range parts { parts[i] = url.PathEscape(p) }
-	return strings.Join(parts, "/")
-}
-
-func FileSize(n int64) string {
-	const unit = 1024
-	if n < unit { return fmt.Sprintf("%d B", n) }
-	div, exp := int64(unit), 0
-	for nn := n / unit; nn >= unit && exp < 3; nn /= unit { div *= unit; exp++ }
-	return fmt.Sprintf("%.1f %s", float64(n)/float64(div), []string{"KB","MB","GB","TB"}[exp])
-}
-
-func HTMLFormat(fmtStr string, args ...any) template.HTML {
-	result := fmtStr
-	for i, arg := range args {
-		escaped := template.HTMLEscapeString(fmt.Sprint(arg))
-		result = strings.Replace(result, fmt.Sprintf("%%[%d]s", i+1), escaped, 1)
-		if !strings.Contains(result, fmt.Sprintf("%%[%d]s", i+1)) {
-			result = strings.Replace(result, "%s", escaped, 1)
-			result = strings.Replace(result, "%d", fmt.Sprint(arg), 1)
-		}
-	}
-	return template.HTML(result)
-}
-
-func Dict(values ...any) (map[string]any, error) {
-	if len(values)%2 != 0 { return nil, fmt.Errorf("odd number of Dict args") }
-	dict := make(map[string]any, len(values)/2)
-	for i := 0; i < len(values); i += 2 {
-		key, ok := values[i].(string)
-		if !ok { return nil, fmt.Errorf("Dict keys must be strings") }
-		dict[key] = values[i+1]
-	}
-	return dict, nil
-}
-
-// Locale provides English fallback translations
-type Locale struct{}
-
-func (l Locale) Tr(key string, args ...any) template.HTML {
-	s := LocaleEN[key]
-	if s == "" { s = key }
-	for _, arg := range args {
-		var val string
-		if h, ok := arg.(template.HTML); ok {
-			val = string(h) // already safe HTML — don't double-escape
-		} else {
-			val = template.HTMLEscapeString(fmt.Sprint(arg))
-		}
-		s = strings.Replace(s, "%s", val, 1)
-		s = strings.Replace(s, "%d", fmt.Sprint(arg), 1)
-	}
-	return template.HTML(s)
-}
-
-func (l Locale) TrN(count any, singular, plural string, args ...any) template.HTML {
-	n := 0
-	switch v := count.(type) {
-	case int: n = v
-	case int64: n = int(v)
-	case float64: n = int(v)
-	default: n = 1
-	}
-	key := plural
-	if n == 1 { key = singular }
-	return l.Tr(key, args...)
-}
-
-var LocaleEN = map[string]string{
-	"mail.activate_account.title":    "Activate your %s account",
-	"mail.hi_user_x":                 "Hi %s,",
-	"mail.activate_account.text_1":   "Welcome to %s! Please activate your account by clicking the button below.",
-	"mail.activate_account.text_2":   "This activation link will expire in %s.",
-	"mail.activate_email.title":      "Verify your email address for %s",
-	"mail.activate_email.text":       "Please verify your email address. The link will expire in %s.",
-	"mail.register_notify.title":     "Welcome to %s, %s",
-	"mail.register_notify.text_1":    "Your account on %s has been created successfully.",
-	"mail.register_notify.text_2":    "Your username is: %s",
-	"mail.register_notify.text_3":    "If you need to set a password, visit %s.",
-	"mail.reset_password.title":      "Reset your %s password",
-	"mail.reset_password.text":       "Click the link below to reset your password. It will expire in %s.",
-	"mail.link_not_working_do_paste": "If the button doesn't work, copy and paste this link into your browser:",
-	"mail.team_invite.text_1":        "%s has invited you to join the team %s in the organization %s.",
-	"mail.team_invite.text_2":        "Click the button below to accept the invitation.",
-	"mail.team_invite.text_3":        "This invitation was sent to %s.",
-	"mail.repo.collaborator.added.text": "You have been added as a collaborator on the repository",
-	"mail.view_it_on":                "View it on %s",
-	"mail.repo.transfer.body":        "The repository %s has been transferred to you.",
-	"mail.release.new.text":          "%s published a new release %s in the repository %s.",
-	"mail.release.title":             "Release: %s",
-	"mail.release.note":              "Release Notes:",
-	"mail.release.downloads":         "Downloads",
-	"mail.release.download.zip":      "Source Code (ZIP)",
-	"mail.release.download.targz":    "Source Code (TAR.GZ)",
-	"mail.issue_assigned.pull":       "%s assigned pull request %s to you in the repository %s.",
-	"mail.issue_assigned.issue":      "%s assigned issue %s to you in the repository %s.",
-	"mail.issue.x_mentioned_you":     "%s mentioned you.",
-	"mail.issue.action.close":        "%s closed issue #%d.",
-	"mail.issue.action.reopen":       "%s reopened issue #%d.",
-	"mail.issue.action.merge":        "%s merged pull request #%d into %s.",
-	"mail.issue.action.approve":      "%s approved this change.",
-	"mail.issue.action.reject":       "%s requested changes.",
-	"mail.issue.action.review":       "%s reviewed this change.",
-	"mail.issue.action.review_dismissed": "%s dismissed the review from %s.",
-	"mail.issue.action.ready_for_review": "%s marked this as ready for review.",
-	"mail.issue.action.new":          "%s created issue #%d.",
-	"mail.issue.action.force_push":   "%s force-pushed the %s branch from %s to %s.",
-	"mail.issue.action.push_1":       "%s pushed %d commit to %s.",
-	"mail.issue.action.push_n":       "%s pushed %d commits to %s.",
-	"mail.issue.in_tree_path":        "In %s:",
-	"mail.reply":                    "Reply to this email",
-}
-
-// MockData for each template type
-type TemplateDef struct {
-	Path   string
-	Data   map[string]any
-}
-
-var templates = map[string]TemplateDef{
-	"activate": {
-		Path: "mail/user/auth/activate.tmpl",
-		Data: map[string]any{
-			"DisplayName":     "Alex Johnson",
-			"Code":            "activation-code-abc123",
-			"ActiveCodeLives": "24 hours",
-		},
-	},
-	"activate_email": {
-		Path: "mail/user/auth/activate_email.tmpl",
-		Data: map[string]any{
-			"DisplayName":     "Alex Johnson",
-			"Code":            "verify-code-xyz789",
-			"Email":           "alex@example.com",
-			"ActiveCodeLives": "24 hours",
-		},
-	},
-	"register_notify": {
-		Path: "mail/user/auth/register_notify.tmpl",
-		Data: map[string]any{
-			"DisplayName": "Alex Johnson",
-			"Username":    "alexj",
-		},
-	},
-	"reset_passwd": {
-		Path: "mail/user/auth/reset_passwd.tmpl",
-		Data: map[string]any{
-			"DisplayName":       "Alex Johnson",
-			"Code":              "reset-token-abc123",
-			"ResetPwdCodeLives": "3 hours",
-		},
-	},
-	"team_invite": {
-		Path: "mail/org/team_invite.tmpl",
-		Data: map[string]any{
-			"Inviter":      map[string]any{"DisplayName": "Sarah Chen"},
-			"Team":         map[string]any{"Name": "Core Developers"},
-			"Organization": map[string]any{"DisplayName": "Acme Corp"},
-			"InviteURL":    "https://gitea.example.com/org/team/invite?token=invite-abc",
-			"Invite":       map[string]any{"Email": "alex@example.com"},
-		},
-	},
-	"collaborator": {
-		Path: "mail/repo/collaborator.tmpl",
-		Data: map[string]any{
-			"Subject":  "Collaborator Added to repo",
-			"Link":     "https://gitea.example.com/repo/project",
-			"RepoName": "acme/project",
-		},
-	},
-	"transfer": {
-		Path: "mail/repo/transfer.tmpl",
-		Data: map[string]any{
-			"Subject": "Repository Transfer",
-			"Link":    "https://gitea.example.com/repo/transferred-project",
-			"Repo":    "acme/transferred-project",
-		},
-	},
-	"release": {
-		Path: "mail/repo/release.tmpl",
-		Data: map[string]any{
-			"Subject": "New Release v2.0.0",
-			"Link":    "https://gitea.example.com/repo/project/releases/tag/v2.0.0",
-			"Release": map[string]any{
-				"Publisher":    map[string]any{"Name": "Sarah Chen"},
-				"HTMLURL":      "https://gitea.example.com/repo/project/releases/tag/v2.0.0",
-				"TagName":      "v2.0.0",
-				"Title":        "Version 2.0 -- Major Update",
-				"RenderedNote": "<p>Major new features and performance improvements in this release.</p>",
-				"Repo": map[string]any{
-					"HTMLURL":  "https://gitea.example.com/repo/project",
-					"FullName": "acme/project",
-				},
-				"Attachments": []any{},
-			},
-			"DisableDownloadSourceArchives": false,
-		},
-	},
-	"workflow_run": {
-		Path: "mail/repo/actions/workflow_run.tmpl",
-		Data: map[string]any{
-			"Subject":      "Workflow Run: CI",
-			"RunStatusText": "All jobs passed",
-			"Repo":          map[string]any{"FullName": "acme/project"},
-			"Run": map[string]any{
-				"WorkflowID": "ci.yml",
-				"HTMLURL":    "https://gitea.example.com/repo/project/actions/runs/42",
-			},
-			"Jobs": []map[string]any{
-				{"Name": "build", "Status": "success", "Attempt": 1, "HTMLURL": "https://gitea.example.com/job/1", "Duration": "2m34s"},
-				{"Name": "test", "Status": "success", "Attempt": 1, "HTMLURL": "https://gitea.example.com/job/2", "Duration": "1m12s"},
-				{"Name": "deploy", "Status": "success", "Attempt": 2, "HTMLURL": "https://gitea.example.com/job/3", "Duration": "45s"},
-			},
-		},
-	},
-	"assigned": {
-		Path: "mail/repo/issue/assigned.tmpl",
-		Data: map[string]any{
-			"Subject": "Issue #42 Assigned",
-			"Link":    "https://gitea.example.com/repo/project/issues/42",
-			"Doer":    map[string]any{"Name": "Sarah Chen"},
-			"IsPull":  false,
-			"Issue": map[string]any{
-				"Index": 42,
-				"Repo": map[string]any{
-					"HTMLURL":  "https://gitea.example.com/repo/project",
-					"FullName": "acme/project",
-				},
-			},
-		},
-	},
-	"default": {
-		Path: "mail/repo/issue/default.tmpl",
-		Data: map[string]any{
-			"Subject":    "Re: Issue #42 -- Bug fix",
-			"Link":       "https://gitea.example.com/repo/project/issues/42",
-			"ActionName": "comment",
-			"Doer":       map[string]any{"Name": "Sarah Chen"},
-			"Body":       "This is a comment on the issue with details about the fix.",
-			"CanReply":   true,
-			"IsMention":  false,
-			"IsPull":     false,
-			"Issue": map[string]any{
-				"Index": 42,
-				"PullRequest": map[string]any{
-					"BaseBranch": "main",
-					"BaseRepo": map[string]any{
-						"HTMLURL": "https://gitea.example.com/repo/project",
-					},
-					"HeadBranch": "feature/fix",
-				},
-			},
-			"Comment": map[string]any{
-				"Commits":    []any{},
-				"IsForcePush": false,
-				"Issue": map[string]any{
-					"PullRequest": map[string]any{
-						"BaseRepo": map[string]any{
-							"HTMLURL": "https://gitea.example.com/repo/project",
-						},
-						"HeadBranch": "feature/fix",
-					},
-				},
-			},
-			"ReviewComments": []any{},
-		},
-	},
-}
-
-// discoverThemes scans the themes directory and returns all subdirectory names.
-func discoverThemes(themesDir string) []string {
-	entries, err := os.ReadDir(themesDir)
-	if err != nil {
-		log.Fatalf("Cannot read themes directory %s: %v", themesDir, err)
-	}
-	var themes []string
-	for _, e := range entries {
-		if e.IsDir() {
-			themes = append(themes, e.Name())
-		}
-	}
-	if len(themes) == 0 {
-		log.Fatalf("No theme directories found in %s", themesDir)
-	}
-	return themes
-}
-
-func main() {
-	exe, _ := os.Executable()
-	rootDir := filepath.Dir(exe)
-	// When run with `go run`, use CWD's parent
-	if _, err := os.Stat(filepath.Join(rootDir, "themes")); os.IsNotExist(err) {
-		cwd, _ := os.Getwd()
-		// Try cwd, then cwd's parent
-		for _, d := range []string{cwd, filepath.Dir(cwd)} {
-			if _, e := os.Stat(filepath.Join(d, "themes")); e == nil { rootDir = d; break }
-		}
-	}
-
-	themesDir := filepath.Join(rootDir, "themes")
-	previewDir := filepath.Join(rootDir, "preview")
-
-	result := make(map[string]map[string]string)
-
-	themes := discoverThemes(themesDir)
-	for _, theme := range themes {
-		themeDir := filepath.Join(themesDir, theme)
-		result[theme] = make(map[string]string)
-
-		for tplID, tplDef := range templates {
-			tmplPath := filepath.Join(themeDir, tplDef.Path)
-			tmplContent, err := os.ReadFile(tmplPath)
-			if err != nil {
-				log.Printf("WARN: cannot read %s: %v", tmplPath, err)
-				result[theme][tplID] = fmt.Sprintf("<p style='color:red'>Failed to read template: %s</p>", err)
-				continue
-			}
-
-			// Build data context
-			data := make(map[string]any)
-			for k, v := range tplDef.Data {
-				data[k] = v
-			}
-			data["locale"] = Locale{}
-
-			// Parse and execute
-			tmpl, err := template.New(tplID).Funcs(TemplateFuncs).Parse(string(tmplContent))
-			if err != nil {
-				log.Printf("WARN: parse error %s/%s: %v", theme, tplID, err)
-				result[theme][tplID] = fmt.Sprintf("<p style='color:red'>Parse error: %s</p>", err)
-				continue
-			}
-
-			var buf strings.Builder
-			if err := tmpl.Execute(&buf, data); err != nil {
-				log.Printf("WARN: execute error %s/%s: %v", theme, tplID, err)
-				result[theme][tplID] = fmt.Sprintf("<p style='color:red'>Render error: %s</p>", err)
-				continue
-			}
-
-			// Fix favicon path for preview (official Gitea icon)
-			rendered := strings.Replace(buf.String(),
-				`src="https://about.gitea.com/assets/img/favicon.png"`,
-				`src="https://about.gitea.com/gitea.svg"`, -1)
-			result[theme][tplID] = rendered
-			log.Printf("OK: %s/%s (%d bytes)", theme, tplID, buf.Len())
-		}
-	}
-
-	// Write output as JS (script-loadable, avoids file:// CORS issues)
-	os.MkdirAll(previewDir, 0755)
-	outPath := filepath.Join(previewDir, "rendered.js")
-	outFile, err := os.Create(outPath)
-	if err != nil { log.Fatalf("Cannot create output: %v", err) }
-	defer outFile.Close()
-
-	jsonBytes, err := json.MarshalIndent(result, "", "  ")
-	if err != nil { log.Fatalf("JSON marshal error: %v", err) }
-
-	outFile.WriteString("// Auto-generated by tools/build-preview.go — do not edit\n")
-	outFile.WriteString("window.__RENDERED__ = ")
-	outFile.Write(jsonBytes)
-	outFile.WriteString(";\n")
-
-	log.Printf("Wrote %d themes x %d templates to %s", len(themes), len(templates), outPath)
-}

tools/cli/commands.go

@@ -0,0 +1,8 @@
+package cli
+
+// Package cli defines all subcommands for the Gitea Mail Templates CLI tool.
+// Command definitions use github.com/urfave/cli/v2.
+//
+// Shared flag names used across multiple subcommands:
+//   --folder  : path to the themes directory
+//   --config  : path to templates_config.json

tools/cli/create.go

@@ -0,0 +1,86 @@
+package cli
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"github.com/urfave/cli/v2"
+
+	"gitea-mail-templates/tools/config"
+)
+
+// CreateCommand returns the "create" subcommand.
+func CreateCommand() *cli.Command {
+	return &cli.Command{
+		Name:      "create",
+		Usage:     "Create one or more new theme style directories",
+		UsageText: "go run . create [--folder <themes-dir>] [--config <config-file>] <style-name>...",
+		Flags: []cli.Flag{
+			&cli.StringFlag{
+				Name:  "folder",
+				Value: "../themes",
+				Usage: "Path to the themes directory",
+			},
+			&cli.StringFlag{
+				Name:  "config",
+				Value: "./data/templates_config.json",
+				Usage: "Path to templates_config.json",
+			},
+		},
+		Action: runCreate,
+	}
+}
+
+func runCreate(c *cli.Context) error {
+	names := c.Args().Slice()
+	if len(names) == 0 {
+		return fmt.Errorf("at least one style name is required")
+	}
+
+	folder := c.String("folder")
+	cfg, err := config.Load(c.String("config"))
+	if err != nil {
+		return err
+	}
+
+	for _, styleName := range names {
+		styleDir := filepath.Join(folder, styleName)
+
+		if info, err := os.Stat(styleDir); err == nil {
+			if info.IsDir() {
+				fmt.Printf("  [skip] '%s' already exists\n", styleName)
+				continue
+			}
+			return fmt.Errorf("'%s' exists but is not a directory", styleName)
+		}
+
+		created := 0
+		for _, tplCfg := range cfg.Templates {
+			tmplPath := filepath.Join(styleDir, tplCfg.PathStr())
+			dir := filepath.Dir(tmplPath)
+
+			if err := os.MkdirAll(dir, 0755); err != nil {
+				return fmt.Errorf("cannot create directory %s: %w", dir, err)
+			}
+
+			placeholder := fmt.Sprintf("<!DOCTYPE html>\n<html>\n<head>\n"+
+				"  <meta http-equiv=\"Content-Type\" content=\"text/html; charset=utf-8\" />\n"+
+				"  <meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0\" />\n"+
+				"  <title>{{.locale.Tr \"mail.%s.title\"}}</title>\n"+
+				"  <style type=\"text/css\">\n    /* TODO: Add your custom styles here */\n"+
+				"  </style>\n</head>\n<body style=\"margin:0;padding:0;\">\n"+
+				"  <!-- TODO: Add your custom template design for: %s -->\n"+
+				"</body>\n</html>\n", tplCfg.Name, tplCfg.Desc)
+
+			if err := os.WriteFile(tmplPath, []byte(placeholder), 0644); err != nil {
+				return fmt.Errorf("cannot write %s: %w", tmplPath, err)
+			}
+			created++
+		}
+
+		fmt.Printf("  Created style '%s' with %d template files\n", styleName, created)
+	}
+
+	return nil
+}

tools/cli/delete.go

@@ -0,0 +1,51 @@
+package cli
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"github.com/urfave/cli/v2"
+)
+
+// DeleteCommand returns the "delete" subcommand.
+func DeleteCommand() *cli.Command {
+	return &cli.Command{
+		Name:      "delete",
+		Usage:     "Delete one or more theme style directories",
+		UsageText: "go run . delete [--folder <themes-dir>] <style-name>...",
+		Flags: []cli.Flag{
+			&cli.StringFlag{
+				Name:  "folder",
+				Value: "../themes",
+				Usage: "Path to the themes directory",
+			},
+		},
+		Action: runDelete,
+	}
+}
+
+func runDelete(c *cli.Context) error {
+	names := c.Args().Slice()
+	if len(names) == 0 {
+		return fmt.Errorf("at least one style name is required")
+	}
+
+	folder := c.String("folder")
+
+	for _, styleName := range names {
+		styleDir := filepath.Join(folder, styleName)
+
+		if _, err := os.Stat(styleDir); os.IsNotExist(err) {
+			fmt.Printf("  [skip] '%s' does not exist\n", styleName)
+			continue
+		}
+
+		if err := os.RemoveAll(styleDir); err != nil {
+			return fmt.Errorf("cannot delete %s: %w", styleDir, err)
+		}
+		fmt.Printf("  Deleted style '%s'\n", styleName)
+	}
+
+	return nil
+}

tools/cli/list.go

@@ -0,0 +1,57 @@
+package cli
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"sort"
+
+	"github.com/urfave/cli/v2"
+
+	"gitea-mail-templates/tools/preview"
+)
+
+// ListCommand returns the "list" subcommand.
+func ListCommand() *cli.Command {
+	return &cli.Command{
+		Name:      "list",
+		Usage:     "List available theme styles in the target folder",
+		UsageText: "go run . list [--folder <themes-dir>]",
+		Flags: []cli.Flag{
+			&cli.StringFlag{
+				Name:  "folder",
+				Value: "../themes",
+				Usage: "Path to the themes directory",
+			},
+		},
+		Action: runList,
+	}
+}
+
+func runList(c *cli.Context) error {
+	folder := c.String("folder")
+
+	themes, err := preview.DiscoverThemes(folder)
+	if err != nil {
+		return err
+	}
+
+	absDir, _ := filepath.Abs(folder)
+	fmt.Printf("Available styles in '%s' (%d):\n", filepath.Base(absDir), len(themes))
+
+	sort.Strings(themes)
+	for _, t := range themes {
+		count := 0
+		filepath.Walk(filepath.Join(folder, t), func(path string, info os.FileInfo, err error) error {
+			if err != nil {
+				return nil
+			}
+			if filepath.Ext(path) == ".tmpl" {
+				count++
+			}
+			return nil
+		})
+		fmt.Printf("  %-16s (%d .tmpl files)\n", t, count)
+	}
+	return nil
+}

tools/cli/preview_cmd.go

@@ -0,0 +1,85 @@
+package cli
+
+import (
+	"fmt"
+	"log"
+	"path/filepath"
+
+	"github.com/urfave/cli/v2"
+
+	"gitea-mail-templates/tools/config"
+	"gitea-mail-templates/tools/preview"
+)
+
+// PreviewCommand returns the "preview" subcommand.
+func PreviewCommand() *cli.Command {
+	return &cli.Command{
+		Name:  "preview",
+		Usage: "Pre-render mail templates for preview/testing",
+		UsageText: `go run . preview [--folder <themes-dir>] [--config <config-file>] [--output <output.js>] all
+   go run . preview [--folder <themes-dir>] [--config <config-file>] <style-name>...`,
+		Flags: []cli.Flag{
+			&cli.StringFlag{
+				Name:  "folder",
+				Value: "../themes",
+				Usage: "Path to the themes directory",
+			},
+			&cli.StringFlag{
+				Name:  "config",
+				Value: "./data/templates_config.json",
+				Usage: "Path to templates_config.json",
+			},
+			&cli.StringFlag{
+				Name:  "output",
+				Usage: "Path to output rendered.js (default: derived from --folder)",
+			},
+		},
+		Action: runPreview,
+	}
+}
+
+func runPreview(c *cli.Context) error {
+	folder := c.String("folder")
+	configPath := c.String("config")
+
+	outputPath := c.String("output")
+	if outputPath == "" {
+		outputPath = filepath.Join(filepath.Dir(folder), "preview", "rendered.js")
+	}
+
+	names := c.Args().Slice()
+	if len(names) == 0 {
+		return fmt.Errorf("specify style names or 'all' (e.g. go run . preview all)")
+	}
+
+	cfg, err := config.Load(configPath)
+	if err != nil {
+		return err
+	}
+
+	var themeFilter map[string]bool
+	if len(names) == 1 && names[0] == "all" {
+		themeFilter = nil
+	} else {
+		themeFilter = make(map[string]bool)
+		for _, name := range names {
+			themeFilter[name] = true
+		}
+	}
+
+	result := preview.RenderAll(folder, cfg, themeFilter)
+	if result == nil {
+		return fmt.Errorf("no results produced")
+	}
+
+	if err := preview.WriteRenderedJS(result, outputPath); err != nil {
+		return err
+	}
+
+	preview.PrintDetailedSummary(result, folder, cfg)
+
+	log.Printf("Wrote %d themes x %d templates to %s",
+		len(result.Summaries), len(cfg.Templates), outputPath)
+
+	return nil
+}

tools/config/config.go

@@ -0,0 +1,85 @@
+package config
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// TemplateConfig holds metadata for a single mail template type.
+type TemplateConfig struct {
+	Name   string         `json:"name"`
+	Desc   string         `json:"desc"`
+	Path   []string       `json:"path"`
+	Params map[string]any `json:"params"`
+}
+
+// TemplatesConfig is the root structure of templates_config.json.
+type TemplatesConfig struct {
+	Templates map[string]TemplateConfig `json:"templates"`
+}
+
+// Load reads and parses a templates_config.json file.
+func Load(path string) (*TemplatesConfig, error) {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("cannot read config file %s: %w", path, err)
+	}
+
+	var cfg TemplatesConfig
+	if err := json.Unmarshal(data, &cfg); err != nil {
+		return nil, fmt.Errorf("cannot parse config file %s: %w", path, err)
+	}
+
+	if len(cfg.Templates) == 0 {
+		return nil, fmt.Errorf("config file %s contains no template definitions", path)
+	}
+
+	return &cfg, nil
+}
+
+// PathStr returns the file path of a template definition joined with OS separator.
+func (t *TemplateConfig) PathStr() string {
+	return filepath.Join(t.Path...)
+}
+
+// Registry builds a lookup map suitable for serializing into rendered.js
+// as window.__REGISTRY__: maps template ID → {name, desc, path}.
+func Registry(cfg *TemplatesConfig) map[string]map[string]string {
+	reg := make(map[string]map[string]string, len(cfg.Templates))
+	for id, t := range cfg.Templates {
+		reg[id] = map[string]string{
+			"name": t.Name,
+			"desc": t.Desc,
+			"path": strings.Join(t.Path, "/"),
+		}
+	}
+	return reg
+}
+
+// FlattenParams converts nested template params into a flat dot-notation map
+// suitable for the preview panel display in rendered.js.
+func FlattenParams(params map[string]any) map[string]string {
+	flat := make(map[string]string)
+	flatten("", params, flat)
+	return flat
+}
+
+func flatten(prefix string, val any, out map[string]string) {
+	switch v := val.(type) {
+	case map[string]any:
+		for k, inner := range v {
+			key := k
+			if prefix != "" {
+				key = prefix + "." + k
+			}
+			flatten(key, inner, out)
+		}
+	case []any:
+		out[prefix] = fmt.Sprintf("[%d items]", len(v))
+	default:
+		out[prefix] = fmt.Sprintf("%v", v)
+	}
+}

tools/data/templates_config.json

@@ -0,0 +1,176 @@
+{
+  "templates": {
+    "activate": {
+      "name": "Activate Account",
+      "desc": "Account activation — sent when a new user registers.",
+      "path": ["mail", "user", "auth", "activate.tmpl"],
+      "params": {
+        "DisplayName": "Alex Johnson",
+        "Code": "activation-code-abc123",
+        "ActiveCodeLives": "24 hours"
+      }
+    },
+    "activate_email": {
+      "name": "Activate Email",
+      "desc": "Email address verification — sent when adding or changing an email address.",
+      "path": ["mail", "user", "auth", "activate_email.tmpl"],
+      "params": {
+        "DisplayName": "Alex Johnson",
+        "Code": "verify-code-xyz789",
+        "Email": "alex@example.com",
+        "ActiveCodeLives": "24 hours"
+      }
+    },
+    "register_notify": {
+      "name": "Register Notify",
+      "desc": "Registration notification — confirms successful account registration.",
+      "path": ["mail", "user", "auth", "register_notify.tmpl"],
+      "params": {
+        "DisplayName": "Alex Johnson",
+        "Username": "alexj"
+      }
+    },
+    "reset_passwd": {
+      "name": "Reset Password",
+      "desc": "Password reset — sent when user requests a password reset link.",
+      "path": ["mail", "user", "auth", "reset_passwd.tmpl"],
+      "params": {
+        "DisplayName": "Alex Johnson",
+        "Code": "reset-token-abc123",
+        "ResetPwdCodeLives": "3 hours"
+      }
+    },
+    "team_invite": {
+      "name": "Team Invite",
+      "desc": "Team invitation — sent when a user is invited to join an organization team.",
+      "path": ["mail", "org", "team_invite.tmpl"],
+      "params": {
+        "Inviter": { "DisplayName": "Sarah Chen" },
+        "Team": { "Name": "Core Developers" },
+        "Organization": { "DisplayName": "Acme Corp" },
+        "InviteURL": "https://gitea.example.com/org/team/invite?token=invite-abc",
+        "Invite": { "Email": "alex@example.com" }
+      }
+    },
+    "collaborator": {
+      "name": "Collaborator Added",
+      "desc": "Collaborator added — sent when a user is added as a repository collaborator.",
+      "path": ["mail", "repo", "collaborator.tmpl"],
+      "params": {
+        "Subject": "Collaborator Added to repo",
+        "Link": "https://gitea.example.com/repo/project",
+        "RepoName": "acme/project"
+      }
+    },
+    "transfer": {
+      "name": "Repository Transfer",
+      "desc": "Repository transfer — sent when repository ownership is transferred.",
+      "path": ["mail", "repo", "transfer.tmpl"],
+      "params": {
+        "Subject": "Repository Transfer",
+        "Link": "https://gitea.example.com/repo/transferred-project",
+        "Repo": "acme/transferred-project"
+      }
+    },
+    "release": {
+      "name": "New Release",
+      "desc": "New release — sent when a new release is published.",
+      "path": ["mail", "repo", "release.tmpl"],
+      "params": {
+        "Subject": "New Release v2.0.0",
+        "Link": "https://gitea.example.com/repo/project/releases/tag/v2.0.0",
+        "Release": {
+          "Publisher": { "Name": "Sarah Chen" },
+          "HTMLURL": "https://gitea.example.com/repo/project/releases/tag/v2.0.0",
+          "TagName": "v2.0.0",
+          "Title": "Version 2.0 -- Major Update",
+          "RenderedNote": "<p>Major new features and performance improvements in this release.</p>",
+          "Repo": {
+            "HTMLURL": "https://gitea.example.com/repo/project",
+            "FullName": "acme/project"
+          },
+          "Attachments": []
+        },
+        "DisableDownloadSourceArchives": false
+      }
+    },
+    "workflow_run": {
+      "name": "Workflow Run",
+      "desc": "Workflow run — sent when a CI/CD workflow completes.",
+      "path": ["mail", "repo", "actions", "workflow_run.tmpl"],
+      "params": {
+        "Subject": "Workflow Run: CI",
+        "RunStatusText": "All jobs passed",
+        "Repo": { "FullName": "acme/project" },
+        "Run": {
+          "WorkflowID": "ci.yml",
+          "HTMLURL": "https://gitea.example.com/repo/project/actions/runs/42"
+        },
+        "Jobs": [
+          { "Name": "build", "Status": "success", "Attempt": 1, "HTMLURL": "https://gitea.example.com/job/1", "Duration": "2m34s" },
+          { "Name": "test", "Status": "success", "Attempt": 1, "HTMLURL": "https://gitea.example.com/job/2", "Duration": "1m12s" },
+          { "Name": "deploy", "Status": "success", "Attempt": 2, "HTMLURL": "https://gitea.example.com/job/3", "Duration": "45s" }
+        ]
+      }
+    },
+    "assigned": {
+      "name": "Issue Assigned",
+      "desc": "Issue/PR assigned — sent when an issue or pull request is assigned.",
+      "path": ["mail", "repo", "issue", "assigned.tmpl"],
+      "params": {
+        "Subject": "Issue #42 Assigned",
+        "Link": "https://gitea.example.com/repo/project/issues/42",
+        "Doer": { "Name": "Sarah Chen" },
+        "IsPull": false,
+        "Issue": {
+          "Index": 42,
+          "Repo": {
+            "HTMLURL": "https://gitea.example.com/repo/project",
+            "FullName": "acme/project"
+          }
+        }
+      }
+    },
+    "default": {
+      "name": "Issue Update",
+      "desc": "Issue/PR update — comments, mentions, reviews, merges, and other activity.",
+      "path": ["mail", "repo", "issue", "default.tmpl"],
+      "params": {
+        "Subject": "Re: Issue #42 -- Bug fix",
+        "Link": "https://gitea.example.com/repo/project/issues/42",
+        "ActionName": "comment",
+        "Doer": { "Name": "Sarah Chen" },
+        "Body": "This is a comment on the issue with details about the fix.",
+        "CanReply": true,
+        "IsMention": false,
+        "IsPull": false,
+        "Issue": {
+          "Index": 42,
+          "PullRequest": {
+            "BaseBranch": "main",
+            "BaseRepo": {
+              "HTMLURL": "https://gitea.example.com/repo/project"
+            },
+            "HeadBranch": "feature/fix"
+          }
+        },
+        "Comment": {
+          "Commits": [],
+          "IsForcePush": false,
+          "OldCommit": "",
+          "NewCommit": "",
+          "Review": { "Reviewer": { "Name": "Taylor Kim" } },
+          "Issue": {
+            "PullRequest": {
+              "BaseRepo": {
+                "HTMLURL": "https://gitea.example.com/repo/project"
+              },
+              "HeadBranch": "feature/fix"
+            }
+          }
+        },
+        "ReviewComments": []
+      }
+    }
+  }
+}

tools/go.mod

@@ -1,3 +1,10 @@
 module gitea-mail-templates/tools
 
 go 1.21
+
+require (
+	github.com/cpuguy83/go-md2man/v2 v2.0.7 // indirect
+	github.com/russross/blackfriday/v2 v2.1.0 // indirect
+	github.com/urfave/cli/v2 v2.27.7 // indirect
+	github.com/xrash/smetrics v0.0.0-20240521201337-686a1a2994c1 // indirect
+)

tools/go.sum

@@ -0,0 +1,8 @@
+github.com/cpuguy83/go-md2man/v2 v2.0.7 h1:zbFlGlXEAKlwXpmvle3d8Oe3YnkKIK4xSRTd3sHPnBo=
+github.com/cpuguy83/go-md2man/v2 v2.0.7/go.mod h1:oOW0eioCTA6cOiMLiUPZOpcVxMig6NIQQ7OS05n1F4g=
+github.com/russross/blackfriday/v2 v2.1.0 h1:JIOH55/0cWyOuilr9/qlrm0BSXldqnqwMsf35Ld67mk=
+github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
+github.com/urfave/cli/v2 v2.27.7 h1:bH59vdhbjLv3LAvIu6gd0usJHgoTTPhCFib8qqOwXYU=
+github.com/urfave/cli/v2 v2.27.7/go.mod h1:CyNAG/xg+iAOg0N4MPGZqVmv2rCoP267496AOXUZjA4=
+github.com/xrash/smetrics v0.0.0-20240521201337-686a1a2994c1 h1:gEOO8jv9F4OT7lGCjxCBTO/36wtF6j2nSip77qHd4x4=
+github.com/xrash/smetrics v0.0.0-20240521201337-686a1a2994c1/go.mod h1:Ohn+xnUBiLI6FVj/9LpzZWtj1/D6lUovWYBkxHVV3aM=

tools/preview/engine.go

@@ -0,0 +1,285 @@
+package preview
+
+import (
+	"encoding/json"
+	"fmt"
+	"html/template"
+	"log"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"gitea-mail-templates/tools/config"
+)
+
+// RenderResult holds the rendered HTML for a single template in a single theme.
+type RenderResult struct {
+	HTML    string
+	Size    int64 // bytes of the rendered HTML
+	Error   string
+	Skipped bool // true when the template file was not found
+}
+
+// ThemeSummary collects statistics for one theme directory.
+type ThemeSummary struct {
+	Name           string
+	TotalFiles     int
+	TotalSize      int64 // total size of .tmpl source files
+	RenderedSize   int64 // total size of rendered HTML
+	RenderedCount  int
+	MissingCount   int
+	ErrorCount     int
+	RenderDuration time.Duration
+	Missing        []string                 // template IDs that were not found
+	Errors         []string                 // template IDs that had render errors
+	Results        map[string]*RenderResult // per-template results
+}
+
+// PreviewResult is the full output from a preview run.
+type PreviewResult struct {
+	Rendered  map[string]map[string]string `json:"rendered"`
+	Registry  map[string]map[string]string `json:"registry"`
+	Params    map[string]map[string]string `json:"params"`
+	Summaries []ThemeSummary               `json:"-"`
+}
+
+// DiscoverThemes scans a directory and returns all subdirectory names.
+func DiscoverThemes(themesDir string) ([]string, error) {
+	entries, err := os.ReadDir(themesDir)
+	if err != nil {
+		return nil, fmt.Errorf("cannot read themes directory %s: %w", themesDir, err)
+	}
+	var names []string
+	for _, e := range entries {
+		if e.IsDir() {
+			names = append(names, e.Name())
+		}
+	}
+	if len(names) == 0 {
+		return nil, fmt.Errorf("no theme directories found in %s", themesDir)
+	}
+	return names, nil
+}
+
+// RenderAll renders all templates from the config for all discovered themes.
+// If themeFilter is non-empty, only themes in the filter set are rendered.
+func RenderAll(themesDir string, cfg *config.TemplatesConfig, themeFilter map[string]bool) *PreviewResult {
+	themes, err := DiscoverThemes(themesDir)
+	if err != nil {
+		log.Printf("ERROR: %v", err)
+		return nil
+	}
+
+	// Apply theme filter
+	if len(themeFilter) > 0 {
+		filtered := themes[:0]
+		for _, t := range themes {
+			if themeFilter[t] {
+				filtered = append(filtered, t)
+			}
+		}
+		themes = filtered
+		if len(themes) == 0 {
+			log.Printf("WARN: no themes matched the requested filter")
+			return nil
+		}
+	}
+
+	result := &PreviewResult{
+		Rendered: make(map[string]map[string]string),
+		Registry: config.Registry(cfg),
+	}
+	// Build flattened params for the preview panel
+	result.Params = make(map[string]map[string]string, len(cfg.Templates))
+	for id, t := range cfg.Templates {
+		result.Params[id] = config.FlattenParams(t.Params)
+	}
+
+	for _, themeName := range themes {
+		themeDir := filepath.Join(themesDir, themeName)
+		summary := renderTheme(themeDir, themeName, cfg)
+		result.Summaries = append(result.Summaries, summary)
+
+		if result.Rendered[themeName] == nil {
+			result.Rendered[themeName] = make(map[string]string)
+		}
+		for tplID, rr := range summary.Results {
+			if rr.Error != "" {
+				result.Rendered[themeName][tplID] = fmt.Sprintf(
+					"<p style='color:red'>Render error for %s: %s</p>", tplID, rr.Error)
+			} else if rr.Skipped {
+				result.Rendered[themeName][tplID] = fmt.Sprintf(
+					"<p style='color:red'>Template not found: %s</p>", tplID)
+			} else {
+				result.Rendered[themeName][tplID] = rr.HTML
+			}
+		}
+	}
+
+	return result
+}
+
+func renderTheme(themeDir, themeName string, cfg *config.TemplatesConfig) ThemeSummary {
+	summary := ThemeSummary{
+		Name:    themeName,
+		Results: make(map[string]*RenderResult),
+	}
+
+	start := time.Now()
+
+	for tplID, tplCfg := range cfg.Templates {
+		tmplRelPath := tplCfg.PathStr()
+		tmplAbsPath := filepath.Join(themeDir, tmplRelPath)
+
+		// Check source file existence
+		info, err := os.Stat(tmplAbsPath)
+		if os.IsNotExist(err) {
+			summary.MissingCount++
+			summary.Missing = append(summary.Missing, tplID)
+			summary.Results[tplID] = &RenderResult{Skipped: true}
+			continue
+		}
+		if err != nil {
+			summary.ErrorCount++
+			summary.Errors = append(summary.Errors, tplID)
+			summary.Results[tplID] = &RenderResult{Error: err.Error()}
+			continue
+		}
+		summary.TotalFiles++
+		summary.TotalSize += info.Size()
+
+		// Read template content
+		tmplContent, err := os.ReadFile(tmplAbsPath)
+		if err != nil {
+			summary.ErrorCount++
+			summary.Errors = append(summary.Errors, tplID)
+			summary.Results[tplID] = &RenderResult{Error: fmt.Sprintf("read error: %v", err)}
+			continue
+		}
+
+		// Build data context
+		data := make(map[string]any)
+		for k, v := range tplCfg.Params {
+			data[k] = v
+		}
+		data["locale"] = Locale{}
+
+		// Parse and execute
+		tmpl, err := template.New(tplID).Funcs(TemplateFuncs).Parse(string(tmplContent))
+		if err != nil {
+			summary.ErrorCount++
+			summary.Errors = append(summary.Errors, tplID)
+			summary.Results[tplID] = &RenderResult{Error: fmt.Sprintf("parse error: %v", err)}
+			continue
+		}
+
+		var buf strings.Builder
+		if err := tmpl.Execute(&buf, data); err != nil {
+			summary.ErrorCount++
+			summary.Errors = append(summary.Errors, tplID)
+			summary.Results[tplID] = &RenderResult{Error: fmt.Sprintf("render error: %v", err)}
+			continue
+		}
+
+		rendered := buf.String()
+
+		summary.RenderedCount++
+		summary.RenderedSize += int64(len(rendered))
+		summary.Results[tplID] = &RenderResult{
+			HTML: rendered,
+			Size: int64(len(rendered)),
+		}
+	}
+
+	summary.RenderDuration = time.Since(start)
+	return summary
+}
+
+// WriteRenderedJS writes the preview result to a JavaScript file loaded by preview/index.html.
+func WriteRenderedJS(result *PreviewResult, outputPath string) error {
+	dir := filepath.Dir(outputPath)
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		return fmt.Errorf("cannot create output directory %s: %w", dir, err)
+	}
+
+	outFile, err := os.Create(outputPath)
+	if err != nil {
+		return fmt.Errorf("cannot create output file %s: %w", outputPath, err)
+	}
+	defer outFile.Close()
+
+	outFile.WriteString("// Auto-generated by tools/tools.go — do not edit\n")
+
+	// Write __RENDERED__
+	renderedJSON, err := json.MarshalIndent(result.Rendered, "", "  ")
+	if err != nil {
+		return fmt.Errorf("cannot marshal rendered data: %w", err)
+	}
+	outFile.WriteString("window.__RENDERED__ = ")
+	outFile.Write(renderedJSON)
+	outFile.WriteString(";\n\n")
+
+	// Write __REGISTRY__
+	registryJSON, err := json.MarshalIndent(result.Registry, "", "  ")
+	if err != nil {
+		return fmt.Errorf("cannot marshal registry data: %w", err)
+	}
+	outFile.WriteString("window.__REGISTRY__ = ")
+	outFile.Write(registryJSON)
+	outFile.WriteString(";\n\n")
+
+	// Write __PARAMS__
+	paramsJSON, err := json.MarshalIndent(result.Params, "", "  ")
+	if err != nil {
+		return fmt.Errorf("cannot marshal params data: %w", err)
+	}
+	outFile.WriteString("window.__PARAMS__ = ")
+	outFile.Write(paramsJSON)
+	outFile.WriteString(";\n")
+
+	return nil
+}
+
+// PrintDetailedSummary prints a human-readable summary of the preview results.
+func PrintDetailedSummary(result *PreviewResult, themesDir string, cfg *config.TemplatesConfig) {
+	absDir, _ := filepath.Abs(themesDir)
+	fmt.Printf("\nfound %d styles of possible Gitea mail template in '%s' folder:\n\n",
+		len(result.Summaries), filepath.Base(absDir))
+
+	for _, s := range result.Summaries {
+		if s.MissingCount == 0 && s.ErrorCount == 0 {
+			fmt.Printf("    %-16s all required mail templates are properly rendered, (total %d .tmpl files, %s after, %v)\n",
+				s.Name, s.TotalFiles,
+				formatSize(s.RenderedSize),
+				s.RenderDuration.Round(time.Millisecond))
+		} else {
+			fmt.Printf("    %-16s only %d required mail templates are properly rendered:\n",
+				s.Name, s.RenderedCount)
+			for _, tplID := range s.Missing {
+				if t, ok := cfg.Templates[tplID]; ok {
+					fmt.Printf("        [%s] not found, expected at 'themes/%s/%s'\n",
+						filepath.Base(t.PathStr()), s.Name, t.PathStr())
+				} else {
+					fmt.Printf("        [%s] not found\n", tplID)
+				}
+			}
+			for _, tplID := range s.Errors {
+				if rr, ok := s.Results[tplID]; ok && rr.Error != "" {
+					fmt.Printf("        [%s] render error: %s\n", tplID, rr.Error)
+				} else {
+					fmt.Printf("        [%s] render error\n", tplID)
+				}
+			}
+		}
+	}
+	fmt.Println()
+}
+
+func formatSize(bytes int64) string {
+	const unit = 1024
+	if bytes < unit {
+		return fmt.Sprintf("%dB", bytes)
+	}
+	return fmt.Sprintf("%dKiB", bytes/unit)
+}

tools/preview/funcs.go

@@ -0,0 +1,159 @@
+package preview
+
+import (
+	"fmt"
+	"html/template"
+	"net/url"
+	"strings"
+)
+
+// TemplateFuncs maps Gitea's built-in template functions available in mail templates.
+var TemplateFuncs = template.FuncMap{
+	"AppUrl":             func() string { return "https://gitea.com/" },
+	"AppName":            func() string { return "Gitea" },
+	"DotEscape":          func(s string) template.HTML { return template.HTML(template.HTMLEscapeString(s)) },
+	"QueryEscape":        url.QueryEscape,
+	"ShortSha":           ShortSha,
+	"PathEscapeSegments": PathEscapeSegments,
+	"FileSize":           FileSize,
+	"HTMLFormat":         HTMLFormat,
+	"Dict":               Dict,
+	"gt":                 Gt,  // override built-in for JSON float64/int coercion
+	"lt":                 Lt,
+	"ge":                 Ge,
+	"le":                 Le,
+}
+
+// ShortSha truncates a commit SHA to 10 characters.
+func ShortSha(s string) string {
+	if len(s) > 10 {
+		return s[:10]
+	}
+	return s
+}
+
+// PathEscapeSegments splits a path and URL-escapes each segment.
+func PathEscapeSegments(s string) string {
+	parts := strings.Split(s, "/")
+	for i, p := range parts {
+		parts[i] = url.PathEscape(p)
+	}
+	return strings.Join(parts, "/")
+}
+
+// FileSize formats a byte count as a human-readable string (e.g. "2.5 MB").
+func FileSize(n int64) string {
+	const unit = 1024
+	if n < unit {
+		return fmt.Sprintf("%d B", n)
+	}
+	div, exp := int64(unit), 0
+	for nn := n / unit; nn >= unit && exp < 3; nn /= unit {
+		div *= unit
+		exp++
+	}
+	return fmt.Sprintf("%.1f %s", float64(n)/float64(div), []string{"KB", "MB", "GB", "TB"}[exp])
+}
+
+// HTMLFormat substitutes %s/%d placeholders with HTML-escaped values.
+func HTMLFormat(fmtStr string, args ...any) template.HTML {
+	result := fmtStr
+	for i, arg := range args {
+		escaped := template.HTMLEscapeString(fmt.Sprint(arg))
+		result = strings.Replace(result, fmt.Sprintf("%%[%d]s", i+1), escaped, 1)
+		if !strings.Contains(result, fmt.Sprintf("%%[%d]s", i+1)) {
+			result = strings.Replace(result, "%s", escaped, 1)
+			result = strings.Replace(result, "%d", fmt.Sprint(arg), 1)
+		}
+	}
+	return template.HTML(result)
+}
+
+// Dict builds a map from alternating key/value pairs (used by Gitea's Dict function).
+func Dict(values ...any) (map[string]any, error) {
+	if len(values)%2 != 0 {
+		return nil, fmt.Errorf("odd number of Dict args")
+	}
+	dict := make(map[string]any, len(values)/2)
+	for i := 0; i < len(values); i += 2 {
+		key, ok := values[i].(string)
+		if !ok {
+			return nil, fmt.Errorf("Dict keys must be strings")
+		}
+		dict[key] = values[i+1]
+	}
+	return dict, nil
+}
+
+// toFloat64 coerces a value to float64 if numeric.
+func toFloat64(v any) (float64, bool) {
+	switch val := v.(type) {
+	case float64:
+		return val, true
+	case float32:
+		return float64(val), true
+	case int:
+		return float64(val), true
+	case int64:
+		return float64(val), true
+	case int32:
+		return float64(val), true
+	case int16:
+		return float64(val), true
+	case int8:
+		return float64(val), true
+	case uint:
+		return float64(val), true
+	case uint64:
+		return float64(val), true
+	case uint32:
+		return float64(val), true
+	case uint16:
+		return float64(val), true
+	case uint8:
+		return float64(val), true
+	default:
+		return 0, false
+	}
+}
+
+// Gt is a type-coercing > comparison that handles JSON float64 vs int literals.
+func Gt(a, b any) bool {
+	af, aok := toFloat64(a)
+	bf, bok := toFloat64(b)
+	if aok && bok {
+		return af > bf
+	}
+	// Fallback to string comparison
+	return fmt.Sprint(a) > fmt.Sprint(b)
+}
+
+// Lt is a type-coercing < comparison that handles JSON float64 vs int literals.
+func Lt(a, b any) bool {
+	af, aok := toFloat64(a)
+	bf, bok := toFloat64(b)
+	if aok && bok {
+		return af < bf
+	}
+	return fmt.Sprint(a) < fmt.Sprint(b)
+}
+
+// Ge is a type-coercing >= comparison.
+func Ge(a, b any) bool {
+	af, aok := toFloat64(a)
+	bf, bok := toFloat64(b)
+	if aok && bok {
+		return af >= bf
+	}
+	return fmt.Sprint(a) >= fmt.Sprint(b)
+}
+
+// Le is a type-coercing <= comparison.
+func Le(a, b any) bool {
+	af, aok := toFloat64(a)
+	bf, bok := toFloat64(b)
+	if aok && bok {
+		return af <= bf
+	}
+	return fmt.Sprint(a) <= fmt.Sprint(b)
+}

tools/preview/locale.go

@@ -0,0 +1,96 @@
+package preview
+
+import (
+	"fmt"
+	"html/template"
+	"strings"
+)
+
+// Locale provides English fallback translations, matching Gitea's locale.Tr interface.
+type Locale struct{}
+
+// Tr translates a key and substitutes positional %s/%d arguments.
+// HTML arguments are preserved; plain strings are HTML-escaped.
+func (l Locale) Tr(key string, args ...any) template.HTML {
+	s := LocaleEN[key]
+	if s == "" {
+		s = key
+	}
+	for _, arg := range args {
+		var val string
+		if h, ok := arg.(template.HTML); ok {
+			val = string(h) // already safe HTML — don't double-escape
+		} else {
+			val = template.HTMLEscapeString(fmt.Sprint(arg))
+		}
+		s = strings.Replace(s, "%s", val, 1)
+		s = strings.Replace(s, "%d", fmt.Sprint(arg), 1)
+	}
+	return template.HTML(s)
+}
+
+// TrN picks singular/plural by count, then delegates to Tr.
+func (l Locale) TrN(count any, singular, plural string, args ...any) template.HTML {
+	n := 0
+	switch v := count.(type) {
+	case int:
+		n = v
+	case int64:
+		n = int(v)
+	case float64:
+		n = int(v)
+	default:
+		n = 1
+	}
+	key := plural
+	if n == 1 {
+		key = singular
+	}
+	return l.Tr(key, args...)
+}
+
+// LocaleEN holds all English translation strings used by Gitea mail templates.
+var LocaleEN = map[string]string{
+	"mail.activate_account.title":         "Activate your %s account",
+	"mail.hi_user_x":                      "Hi %s,",
+	"mail.activate_account.text_1":        "Welcome to %s! Please activate your account by clicking the button below.",
+	"mail.activate_account.text_2":        "This activation link will expire in %s.",
+	"mail.activate_email.title":           "Verify your email address for %s",
+	"mail.activate_email.text":            "Please verify your email address. The link will expire in %s.",
+	"mail.register_notify.title":          "Welcome to %s, %s",
+	"mail.register_notify.text_1":         "Your account on %s has been created successfully.",
+	"mail.register_notify.text_2":         "Your username is: %s",
+	"mail.register_notify.text_3":         "If you need to set a password, visit %s.",
+	"mail.reset_password.title":           "Reset your %s password",
+	"mail.reset_password.text":            "Click the link below to reset your password. It will expire in %s.",
+	"mail.link_not_working_do_paste":      "If the button doesn't work, copy and paste this link into your browser:",
+	"mail.team_invite.text_1":             "%s has invited you to join the team %s in the organization %s.",
+	"mail.team_invite.text_2":             "Click the button below to accept the invitation.",
+	"mail.team_invite.text_3":             "This invitation was sent to %s.",
+	"mail.repo.collaborator.added.text":   "You have been added as a collaborator on the repository",
+	"mail.view_it_on":                     "View it on %s",
+	"mail.repo.transfer.body":             "The repository %s has been transferred to you.",
+	"mail.release.new.text":               "%s published a new release %s in the repository %s.",
+	"mail.release.title":                  "Release: %s",
+	"mail.release.note":                   "Release Notes:",
+	"mail.release.downloads":              "Downloads",
+	"mail.release.download.zip":           "Source Code (ZIP)",
+	"mail.release.download.targz":         "Source Code (TAR.GZ)",
+	"mail.issue_assigned.pull":            "%s assigned pull request %s to you in the repository %s.",
+	"mail.issue_assigned.issue":           "%s assigned issue %s to you in the repository %s.",
+	"mail.issue.x_mentioned_you":          "%s mentioned you.",
+	"mail.issue.action.close":             "%s closed issue #%d.",
+	"mail.issue.action.reopen":            "%s reopened issue #%d.",
+	"mail.issue.action.merge":             "%s merged pull request #%d into %s.",
+	"mail.issue.action.approve":           "%s approved this change.",
+	"mail.issue.action.reject":            "%s requested changes.",
+	"mail.issue.action.review":            "%s reviewed this change.",
+	"mail.issue.action.review_dismissed":  "%s dismissed the review from %s.",
+	"mail.issue.action.ready_for_review":  "%s marked this as ready for review.",
+	"mail.issue.action.new":               "%s created issue #%d.",
+	"mail.issue.action.force_push":        "%s force-pushed the %s branch from %s to %s.",
+	"mail.issue.action.push_1":            "%s pushed %d commit to %s.",
+	"mail.issue.action.push_n":            "%s pushed %d commits to %s.",
+	"mail.issue.in_tree_path":             "In %s:",
+	"mail.reply":                          "Reply to this email",
+}

tools/tools.go

@@ -0,0 +1,29 @@
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/urfave/cli/v2"
+
+	cmds "gitea-mail-templates/tools/cli"
+)
+
+func main() {
+	app := &cli.App{
+		Name:      "tools",
+		Usage:     "Gitea Mail Templates CLI — manage and preview email template themes",
+		UsageText: "tools <command> [args...] [--flags]",
+		Commands: []*cli.Command{
+			cmds.ListCommand(),
+			cmds.CreateCommand(),
+			cmds.DeleteCommand(),
+			cmds.PreviewCommand(),
+		},
+	}
+
+	if err := app.Run(os.Args); err != nil {
+		fmt.Fprintf(os.Stderr, "error: %v\n", err)
+		os.Exit(1)
+	}
+}