diff --git a/PRD.md b/PRD.md
index 412917e..5590b51 100644
--- a/PRD.md
+++ b/PRD.md
@@ -350,6 +350,9 @@ Explicitly *not* React.
 Images are built locally, pushed to a private container registry, then pulled
 on the server and run with Docker Compose.
 
+- **Branches**: `main` carries released versions only, so its history is the
+  deployment history and every release tag points into it. Development happens
+  on `dev` and merges into `main` when a release is cut.
 - **Versioning**: CalVer `vYYYYMMDD-N`, where `N` is the Nth build of that
   day. `make image` derives `N` by counting the day's existing git tags,
   creates the new tag, and bakes the version into the binary through
diff --git a/README.md b/README.md
index 906b27a..d3b8f3c 100644
--- a/README.md
+++ b/README.md
@@ -47,6 +47,19 @@ One static Go binary. No Node.js, no bundler, no separate database server.
 | Auth | HTTP Basic, one shared household password |
 | Runtime image | `FROM scratch` |
 
+## Branches
+
+`main` holds released versions only. Every release tag points at a commit on
+`main`, so its history is the deployment history.
+
+All development happens on `dev`. Merge into `main` when cutting a release,
+then build and push the image from there.
+
+```sh
+git switch dev          # where the work happens
+git switch main && git merge dev && make release
+```
+
 ## Quick start
 
 ```sh