docs: add Gitea version compatibility matrix and badge

- Create COMPATIBILITY.md with version matrix, Gitea release tracking,
  template variable reference, and compatibility verification process
- Add Gitea 1.25+ | 1.26.4 tested badge to README
- Update all 6 READMEs (EN + 5 translations) with latest tested version
  and link to COMPATIBILITY.md
- Include COMPATIBILITY.md in release artifacts

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

.github/workflows/release.yml

@@ -33,7 +33,7 @@ jobs:
           VERSION=${GITHUB_REF#refs/tags/}
           ARCHIVE="gitea-mail-templates-${VERSION}"
           mkdir -p dist
-          cp -r themes LICENSE README.md "dist/${ARCHIVE}"
+          cp -r themes LICENSE README.md COMPATIBILITY.md "dist/${ARCHIVE}"
           cd dist
           zip -r "${ARCHIVE}.zip" "${ARCHIVE}"
           tar -czf "${ARCHIVE}.tar.gz" "${ARCHIVE}"

COMPATIBILITY.md

@@ -0,0 +1,92 @@
+# Gitea Compatibility
+
+This document tracks the compatibility between **Gitea Mail Templates** releases and **Gitea** versions.
+
+## Quick Reference
+
+| Template Release | Min Gitea | Max Tested Gitea | Status |
+|-----------------|-----------|-----------------|--------|
+| **v1.0.x**      | **1.25.0** | **1.26.4** | ✅ Active |
+
+> **Latest verified:** All 11 templates pass validation against Gitea 1.26.4 data contexts.
+
+## Check Your Gitea Version
+
+```bash
+# On your Gitea server:
+gitea --version
+# Or check the web UI footer / Site Administration → Monitoring
+```
+
+## Gitea Version History — Mail Template Impact
+
+| Gitea | Release Date | Mail Template Changes | Breaking? |
+|-------|-------------|----------------------|-----------|
+| **1.26.4** | 2026-06-21 | None — hotfix release | No |
+| **1.26.3** | 2026-06-20 | None — security release | No |
+| **1.26.2** | 2026-05-20 | None — security + bug fixes | No |
+| **1.26.1** | 2026-04-22 | None — bug fixes | No |
+| **1.26.0** | 2026-04-19 | AppURL cleanup; SanitizeHTML deprecated → use HTMLFormat | No |
+| **1.25.5** | 2026-03-10 | None — security + maintenance | No |
+| **1.25.0** | 2025 | **Directory restructure** — templates moved to `mail/<category>/<type>.tmpl` (PR #35150); subject/body split with `---` separator; template preview support added | **Yes** (structural) |
+| **≤ 1.24.x** | — | Flat directory structure under `custom/templates/mail/` | ❌ Unsupported |
+
+## Template Variable Reference
+
+All 11 template types use only Gitea built-in variables and functions. Verified against Gitea source (`services/mailer/` + `modules/templates/mail.go`).
+
+### Template Functions (available in all templates)
+
+| Function | Since Gitea | Notes |
+|----------|------------|-------|
+| `AppName` | ≤ 1.21 | Application name |
+| `AppUrl` | ≤ 1.21 | Application base URL |
+| `AppDomain` | ≤ 1.21 | Server domain |
+| `DotEscape` | ≤ 1.21 | Prevents auto-linking of dotted text |
+| `QueryEscape` | ≤ 1.21 | URL query encoding |
+| `PathEscapeSegments` | ≤ 1.21 | Per-segment path encoding |
+| `ShortSha` | ≤ 1.21 | Truncated commit hash |
+| `FileSize` | ≤ 1.21 | Human-readable file size |
+| `HTMLFormat` | ≤ 1.21 | Render string as safe HTML |
+| `Iif` | ≤ 1.21 | Inline conditional |
+| `dict` | ≤ 1.21 | Build maps from key-value pairs |
+| `Eval` | ≤ 1.21 | Evaluate template tokens |
+| `StringUtils` | ≤ 1.21 | String manipulation helpers |
+| `SliceUtils` | ≤ 1.21 | Slice manipulation helpers |
+| `JsonUtils` | ≤ 1.21 | JSON helpers |
+| `DumpVar` | ≤ 1.21 | Debug variable dump |
+| `SanitizeHTML` | ≤ 1.21 | **Deprecated in 1.26** — use `HTMLFormat` |
+
+### Data Contexts by Template
+
+| Template | Key Variables |
+|----------|--------------|
+| `user/auth/activate` | `DisplayName`, `Code`, `ActiveCodeLives` |
+| `user/auth/activate_email` | `DisplayName`, `Code`, `Email`, `ActiveCodeLives` |
+| `user/auth/register_notify` | `DisplayName`, `Username` |
+| `user/auth/reset_passwd` | `DisplayName`, `Code`, `ResetPwdCodeLives` |
+| `org/team_invite` | `Inviter`, `Team`, `Organization`, `InviteURL`, `Invite` |
+| `repo/collaborator` | `Subject`, `RepoName`, `Link` |
+| `repo/transfer` | `Doer`, `User`, `Repo`, `Link`, `Destination` |
+| `repo/release` | `Release` (with `Publisher`, `TagName`, `Title`, `RenderedNote`, `Attachments`), `Link` |
+| `repo/actions/workflow_run` | `Run` (with `WorkflowID`, `HTMLURL`), `Jobs`, `RunStatusText` |
+| `repo/issue/assigned` | `Doer`, `Issue`, `Link`, `IsPull` |
+| `repo/issue/default` | `Doer`, `Issue`, `Link`, `Body`, `ActionName`, `Comment`, `IsPull`, `IsMention`, `ReviewComments`, `CanReply` |
+
+> ⚠️ **`.DisplayName`** is not available in collaborator, transfer, release, workflow_run, assigned, and default templates — do not reference it.
+
+### Translation Keys
+
+All templates use Gitea's official `mail.*` translation namespace. Keys are stable across Gitea 1.25+.
+
+## How Compatibility Is Verified
+
+1. **Automated lint** — CI renders all templates via `go run . preview all` on every push
+2. **Source audit** — Template data contexts are cross-referenced against Gitea's `services/mailer/` package
+3. **Release checklist** — Each release confirms the max-tested Gitea version in this file
+
+## Reporting Issues
+
+If you find a compatibility problem with a specific Gitea version:
+1. Check the [Gitea changelog](https://github.com/go-gitea/gitea/blob/main/CHANGELOG.md) for recent mail template changes
+2. Open an issue with: your Gitea version, which template, and the error

README.md

@@ -2,6 +2,8 @@
 
 A curated collection of professionally designed, audience-driven email templates for self-hosted [Gitea](https://about.gitea.com) instances.
 
+[![Gitea](https://img.shields.io/badge/Gitea-1.25+%20%7C%201.26.4%20tested-blue)](COMPATIBILITY.md)
+
 > **110 template files — 10 visual styles, 11 email types each**
 
 ---
@@ -161,10 +163,10 @@ gitea-mail-templates/
 
 ## Compatibility
 
-- **Gitea 1.25+** — matches the refactored mail template directory structure introduced in v1.25
+- **Gitea 1.25+** — matches the refactored mail template directory structure (v1.25)
-- 100% variable-compatible with official Gitea templates
+- **Latest tested:** Gitea 1.26.4
-- Uses only built-in Gitea template functions
+- 100% variable-compatible with official Gitea templates — see [COMPATIBILITY.md](COMPATIBILITY.md) for the full matrix
-- Uses only official Gitea translation keys
+- Uses only built-in Gitea template functions and official translation keys
 - No custom template functions or locale patches required
 
 ---

docs/README.ja.md

@@ -57,7 +57,9 @@ cd tools && go run . dev
 
 ## 互換性
 
-- **Gitea 1.25+**, 100%互換, 組み込み関数のみ
+- **Gitea 1.25+** — v1.25で導入されたメールテンプレートディレクトリ構造
+- **最新テスト:** Gitea 1.26.4
+- Gitea公式テンプレートと100%互換 — 詳細は [COMPATIBILITY.md](COMPATIBILITY.md)を参照
 
 ## ライセンス
 

docs/README.ko.md

@@ -55,3 +55,12 @@ cd tools && go run . dev
 # → http://localhost:3456
 ```
 
+## 호환성
+
+- **Gitea 1.25+** — v1.25에서 도입된 메일 템플릿 디렉토리 구조 사용
+- **최신 테스트:** Gitea 1.26.4
+- Gitea 공식 템플릿과 100% 호환 — 자세한 내용은 [COMPATIBILITY.md](../COMPATIBILITY.md) 참조
+
+## 라이선스
+
+MIT — [LICENSE](../LICENSE).

docs/README.ru.md

@@ -57,7 +57,9 @@ cd tools && go run . dev
 
 ## Совместимость
 
-- **Gitea 1.25+**, 100% совместимость, только встроенные функции
+- **Gitea 1.25+** — структура директорий из v1.25
+- **Последняя проверка:** Gitea 1.26.4
+- 100% совместимость с официальными шаблонами Gitea — см. [COMPATIBILITY.md](COMPATIBILITY.md)
 
 ## Лицензия
 

docs/README.zh-CN.md

@@ -78,7 +78,9 @@ cd tools && go run . dev
 
 ## 兼容性
 
-- **Gitea 1.25+**，100% 变量兼容，仅使用内置函数和官方翻译键
+- **Gitea 1.25+** — v1.25 引入的邮件模板目录结构
+- **最新测试：** Gitea 1.26.4
+- 与 Gitea 官方模板 100% 兼容 — 详见 [COMPATIBILITY.md](COMPATIBILITY.md)
 
 ## 许可证
 

docs/README.zh-TW.md

@@ -73,7 +73,9 @@ cd tools && go run . dev
 
 ## 相容性
 
-- **Gitea 1.25+**，100% 變數相容，僅使用內建函式和官方翻譯鍵
+- **Gitea 1.25+** — v1.25 引入的郵件模板目錄結構
+- **最新測試：** Gitea 1.26.4
+- 與 Gitea 官方模板 100% 相容 — 詳見 [COMPATIBILITY.md](COMPATIBILITY.md)
 
 ## 授權