merge 1.21 branch

docs/.vitepress/ext/l10n/locales.ts

@@ -151,10 +151,10 @@ function buildNav(text: string[], lang?: string): DefaultTheme.NavItem[] {
         { text: text[2], link: buildLink("api") },
         { text: text[3], link: buildLink("support") },
         {
-            text: "v1.20", items: [
+            text: "v1.21", items: [
                 { text: "Changelog", link: "/releases" },
                 { text: "Contributing", link: "https://github.com/naninovel/docs/blob/main/CONTRIBUTING.md" },
-                { text: "v1.21-preview", link: "https://pre.naninovel.com/guide" }
+                { text: "v1.20-stable", link: "https://naninovel.com/guide" }
             ]
         }
     ];

docs/releases/1.21.md

@@ -0,0 +1,38 @@
+# 1.21 Release Notes
+
+Release date: Q4 2025 (ETA)
+
+::: info NOTE
+**This is a preview work-in-progress release, which may have breaking changes introduced at any time.** Choose it if you're in the early development stages or need a specific feature unavailable in the stable release. Note that preview releases are not published on Unity's Asset Store and have to be [installed from GitHub](/guide/getting-started#install-from-github).
+:::
+
+## Compatibility
+
+Supported Unity versions range: `6000.0 - 6000.1`
+
+Only LTS releases in the range are supported. Any issues with the future Unity releases will be addressed in the next Naninovel releases. Compatible Unity versions for past releases are specified in the [release notes](https://pre.naninovel.com/releases).
+
+## Upgrade Guide
+
+When upgrading a project with Naninovel version 1.18 or older first follow [v1.19 release](/releases/1.19) upgrade guide, then continue with the following instructions:
+
+1. Backup the project or use a [VCS](https://en.wikipedia.org/wiki/Version_control) to be able to rollback in case something goes wrong.
+2. In case using [VS Code extension](/guide/ide-extension), update both the extension and VS Code itself to the latest versions, then run `Naninovel: Purge Cached Metadata` command via `View -> Command Palette` and restart VS Code.
+3. ...
+
+> [!WARNING]
+> In-game saves (slots in save/load menu, values in settings menu and global game state) created with previous versions may cause undefined behavior when loaded with the updated version; when patching a shipped project with a new Naninovel version, make sure existing saves work as expected.
+
+## Added
+
+- ...
+
+## Changed
+
+- ...
+
+## Fixed
+
+Most fixes associated with bugs found during the pre-release stage are backported to the previous stable release and are not listed here; find them at the "Patches" section of the previous release changelog.
+
+- ...