docs for new git persistence mode

docs/codeflow/git-persistence.md

@@ -0,0 +1,52 @@
+---
+title: Git projects and persistence
+description: 'How persistence works in the StackBlitz editor for Git repositories'
+og_image: what-is-codeflow.png
+---
+
+# {{ $frontmatter.title }}
+
+The StackBlitz editor has some differences with respect to _persistence_ (whether and how we store your changes) between _projects_ and Git repositories.
+
+## Default mode
+
+In its default mode, the StackBlitz editor **does _not_ store your changes** when you open a Git repository (for instance, https://stackblitz.com/~/github.com/vitejs/vite). You can edit files, create new commits and push them to a remote. However, any intermediate changes that are not pushed will be lost after reloading the page. The editor shows a prominent warning to remind you when persistence is off.
+
+ This is in constrast with _projects_, which always keep your changes stored in the StackBlitz backend. The rough rationale for this difference in behavior is that, for Git-based projects, the ultimate goal is to push some new changes into a remote that already exists. This remote ultimately acts as your storage.
+
+## Persistence in Git repositories
+
+As a convenience, the StackBlitz editor _does_ persist your changes in some scenarios, even when working on Git repositories. The "rules" are:
+
+* You should be logged in, and
+* You should have push permissions for the repository, and
+* You should not be working on the default branch.
+
+These conditions should enable you to leverage persistence in the commmon use case of working on a feature branch, either in a repository of yours or a fork of a project that you want to contribute to.
+
+The last condition is not as strict as the others: when you are in the default branch, you can opt-in into persisting your changes.
+
+We might relax these conditions on the future and enable persistence in more scenarios.
+
+## Branching model
+
+For Git-based projects, the StackBlitz editor establishes a one-to-one relation between your URL and the branch that you are working on. You can create new branches, push them to a remote, etc. But working on a different branch, that is, in Git parlance, _checking out_ a different branch requires you to **navigate to its corresponding URL**, in your current tab or a new one.
+
+For instance, if you open the repository for these docs, you would go to
+
+> https://stackblitz.com/~/github.com/stackblitz/docs.
+
+If you change branches through the branch picker or the editor command `Checkout to...`, you will be prompted to navigate away to the corresponding URL, for instance
+
+> https://stackblitz.com/~/github.com/stackblitz/docs/tree/foobar
+
+for a branch named `foobar`.
+
+## Merging conflicts
+
+If you work on a certain branch and persistence is enabled (as described above), the StackBlitz editor stores your intermediate changes not yet pushed to a remote. If you open the same branch at a later point, new commits from the remote could conflict with your stored changes. When this happens, the editor presents several ways to deal with this situation:
+
+* Discard your old changes and start working fresh again from the latest commit.
+* Push your ongoing changes to an intermediate branch and create a pull request.
+
+We are looking into enabling more sophisticated conflict resolution strategies.

docs/links.ts

@@ -33,6 +33,10 @@ const groupLinks: Record<MenuLinkGroup, MenuLinkItem[]> = {
       text: 'Content updates with Web Publisher',
       link: '/codeflow/content-updates-with-web-publisher',
     },
+    {
+      text: 'Git projects and persistence',
+      link: '/codeflow/git-persistence',
+    },
     { text: 'Integrating Web Publisher', link: '/codeflow/integrating-web-publisher' },
     { text: 'Codeflow FAQ', link: '/codeflow/codeflow-faq' },
   ],