SimpleITK · zivy · Aug 13, 2026 · Aug 11, 2026 · Aug 11, 2026 · Aug 11, 2026
diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
@@ -2,13 +2,15 @@ on:
   push:
     branches:
       - main
+      - 'release-*'
     tags:
       - 'v*'  # Trigger on version tags
     paths-ignore:
       - 'SimpleITK_Foyer/**'
   pull_request:
     branches:
       - main
+      - 'release-*'
     paths-ignore:
       - 'SimpleITK_Foyer/**'
   workflow_dispatch:
@@ -30,7 +32,7 @@ jobs:
         # Build against oldest patch versions x.y.0 as R is forward
         # compatible.
         R: [ '4.4.0', '4.5.0', '4.6.0' ]
-        os: [ 'macos-15-intel', 'windows-latest']
+        os: [ 'macos-15-intel', 'windows-latest' ]
     runs-on: ${{ matrix.os }}
     name: ${{ matrix.R }} ${{ matrix.os }} build
 
@@ -155,7 +157,7 @@ jobs:
       run: |
         dnf install -y epel-release
         dnf install -y --allowerasing \
-          cmake git gcc gcc-c++ make patch \
+          cmake git gcc-toolset-13-gcc gcc-toolset-13-gcc-c++ make patch \
           libcurl-devel openssl-devel libxml2-devel \
           harfbuzz-devel fribidi-devel libssh2-devel \
           curl tar
@@ -188,6 +190,7 @@ jobs:
       env:
         ITK_GLOBAL_DEFAULT_NUMBER_OF_THREADS: 2
       run: |
+        source scl_source enable gcc-toolset-13
         R -e "Sys.setenv(MAKEJ=2); Sys.setenv(ADDITIONAL_SITK_MODULES='-DSimpleITK_USE_ELASTIX=ON'); remotes::install_local('.', lib=Sys.getenv('R_LIBS_USER'), upgrade='never', INSTALL_opts='--build')"
         R -e "library(SimpleITK); Version()"
 
@@ -241,39 +244,51 @@ jobs:
         if [ "${TAG_NAME}" != "${SITK_TARGET}" ]; then
           echo "Tag ${TAG_NAME} does not match SITK_TARGET ${SITK_TARGET}"
           echo "Skipping draft release creation."
-          echo "draft_release=false" >> $GITHUB_OUTPUT
+          echo "create_draft_release=false" >> $GITHUB_OUTPUT
         else
-          echo "draft_release=true" >> $GITHUB_OUTPUT
+          echo "create_draft_release=true" >> $GITHUB_OUTPUT
+        fi
+        # if tag is not vMAJOR.MINOR.PATCH.SUB_PATCH (all numeric) then this is a pre-release
+        if [[ "${TAG_NAME}" =~ ^v[0-9]+\.[0-9]+\.[0-9]+(\.[0-9]+)?$ ]]; then
+          echo "is_prerelease=false" >> $GITHUB_OUTPUT
+        else
+          echo "is_prerelease=true" >> $GITHUB_OUTPUT
         fi
 
     - name: Download all artifacts
-      if: steps.verify_tag.outputs.draft_release == 'true'
+      if: steps.verify_tag.outputs.create_draft_release == 'true'
       uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
       with:
         path: release-artifacts
         pattern: SimpleITK_*
         merge-multiple: true
 
     - name: Display downloaded artifacts
-      if: steps.verify_tag.outputs.draft_release == 'true'
+      if: steps.verify_tag.outputs.create_draft_release == 'true'
       run: |
         echo "Downloaded artifacts:"
         ls -lhR release-artifacts/
 
     - name: Generate release body message with current version
-      if: steps.verify_tag.outputs.draft_release == 'true'
+      if: steps.verify_tag.outputs.create_draft_release == 'true'
       run: |
-        sed 's/{{VERSION}}/${{ github.ref_name }}/g' .github/workflows/release_message_template.md > /tmp/release_body.md
+        if [[ "${{ steps.verify_tag.outputs.is_prerelease }}" == "true" ]]; then
+          TEMPLATE=".github/workflows/pre_release_message_template.md"
+        else
+          TEMPLATE=".github/workflows/release_message_template.md"
+        fi
+        sed 's/{{VERSION}}/${{ github.ref_name }}/g' "${TEMPLATE}" > /tmp/release_body.md
 
     # This action automatically creates the release if it doesn't exist,
     # or updates it if it does.
     - name: Create or Update Draft Release
-      if: steps.verify_tag.outputs.draft_release == 'true'
+      if: steps.verify_tag.outputs.create_draft_release == 'true'
       uses: softprops/action-gh-release@3d0d9888cb7fd7b750713d6e236d1fcb99157228 # v3.0.2
       env:
         GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
       with:
         draft: true
+        prerelease: ${{ steps.verify_tag.outputs.is_prerelease == 'true' }}
         name: SimpleITK ${{ github.ref_name }} R Package Release
         body_path: /tmp/release_body.md
         files: |

diff --git a/.github/workflows/pre_release_message_template.md b/.github/workflows/pre_release_message_template.md
@@ -0,0 +1,14 @@
+**Please manually upload the artifacts from [CircleCI](https://dl.circleci.com/status-badge/redirect/gh/SimpleITK/SimpleITKRInstaller/tree/main), review and test the packages before publishing this release. Then remove this line and make it public.**
+
+Detailed release notes are available on the [main SimpleITK repository](https://github.com/SimpleITK/SimpleITK/releases/{{VERSION}}).
+
+
+Install the package directly from this page, using the URL to the asset which matches your OS and R version:
+
+```r
+install.packages("https://github.com/SimpleITK/SimpleITKRInstaller/releases/download/{{VERSION}}/PACKAGE_FILE", repos = NULL, type = "source")
+```
+
+**Linux GLIBC compatibility note:** The Linux binary package targets GLIBC 2.28, making it compatible with Linux distributions that include GLIBC 2.28 or newer. The oldest supported version per distribution is: Ubuntu 20.04 (Focal Fossa), Debian 10 (Buster), CentOS/RHEL 8, Rocky Linux 8, AlmaLinux 8, Fedora 29, openSUSE Leap 15.3.
+
+If you need a custom build of SimpleITK or the binary package for your platform, R version, or desired SimpleITK version is not available you will need to build the package yourself. To do this, use the [remotes based installer](https://github.com/SimpleITK/SimpleITKRInstaller).
diff --git a/.github/workflows/release_message_template.md b/.github/workflows/release_message_template.md
@@ -30,7 +30,11 @@ The `install_simpleitk` function provides finer installation control such as Sim
 help(install_simpleitk)
 ```
 
-If you directly download the package artifact from this release page, before you install the package you will need to first unzip the file. Then rename it to `SimpleITK_<version>.zip` (windows), `SimpleITK_<version>.tgz` (macOS), or `SimpleITK_<version>.tar.gz` (Linux) to match the expected file name format.
+To install the package directly from this page, using the URL to the asset which matches your OS and R version:
+
+```r
+install.packages("https://github.com/SimpleITK/SimpleITKRInstaller/releases/download/{{VERSION}}/PACKAGE_FILE", repos = NULL, type = "source")
+```
 
 **Linux GLIBC compatibility note:** The Linux binary package targets GLIBC 2.28, making it compatible with Linux distributions that include GLIBC 2.28 or newer. The oldest supported version per distribution is: Ubuntu 20.04 (Focal Fossa), Debian 10 (Buster), CentOS/RHEL 8, Rocky Linux 8, AlmaLinux 8, Fedora 29, openSUSE Leap 15.3.
 

diff --git a/release_instructions.md b/release_instructions.md
@@ -1,29 +1,124 @@
 # Release Instructions
 
-This document describes the steps required to create the binary R release for SimpleITK which updates and relies on the remotes based SimpleITKRInstaller.
+This document describes the steps to create a binary R release for SimpleITK.
 
-1. Create branch off of `main` and switch to it,  `git checkout -b updateRelease main`.
+## Branch and versioning strategy
 
-1. Update the installer `DESCRIPTION` file: change the `SITK_TARGET` field to the desired SimpleITK version (e.g. v2.5.5) and run the version update script (in bash or Git Bash on windows), `sitk_r_version_date.sh`. This script will update the file's `Version` and `Date` fields according to the `SITK_TARGET`.
+- `main` always tracks the highest stable SimpleITK release by semantic version.
+- All locally created branches are pushed directly to the authoritative repository.
+- Short-lived branches, cut from `main`, are used for all new work.
+- Long-lived `release-major.minor` branches created only for old maintenance series (e.g. `release-2.5` after `main` has moved to 3.0) to provide a safe PR target. They are never merged back into `main`.
+
+---
+
+## Releasing on a short-lived branch
+
+Use this process for all releases where `main` is at the same or lower version than the target (e.g. v3.0.0b1, v3.0.0, or v3.0.1 while 3.0 is the leading series).
+
+1. Create a short-lived branch from `main` and switch to it:
+
+    ```
+    git checkout main
+    git pull https://github.com/SimpleITK/SimpleITKRInstaller.git main
+    git checkout -b release-v3.0.0b1
+    ```
+
+1. Update the `DESCRIPTION` file: change `SITK_TARGET` to the desired version (e.g. `v3.0.0b1`) and run the `sitk_r_version_date.sh` script.
+
+1. Commit and push:
+
+    ```
+    git commit -am "Update SimpleITK to v3.0.0b1"
+    git push https://github.com/SimpleITK/SimpleITKRInstaller.git release-v3.0.0b1
+    ```
+
+1. On GitHub open a PR targeting `main`. Verify all builds pass and artifacts are created.
+
+1. Stable release (new highest version) — on GitHub merge the PR (we'll delete the branch later), then tag the HEAD of `main`:
+
+    ```
+    git checkout main
+    git pull https://github.com/SimpleITK/SimpleITKRInstaller.git main
+    git tag -a v3.0.0 -m "Release v3.0.0"
+    git push https://github.com/SimpleITK/SimpleITKRInstaller.git v3.0.0
+    ```
+
+   Prerelease — on GitHub close the PR without merging, then tag its HEAD:
+
+    ```
+    git checkout release-v3.0.0b1
+    git pull https://github.com/SimpleITK/SimpleITKRInstaller.git release-v3.0.0b1
+    git tag -a v3.0.0b1 -m "Release v3.0.0b1"
+    git push https://github.com/SimpleITK/SimpleITKRInstaller.git v3.0.0b1
+    ```
+
+   This branch on the authoritative repository will be deleted in the last step; the tag keeps the commit permanently reachable.
+
+1. Monitor the tag-triggered build at https://github.com/SimpleITK/SimpleITKRInstaller/actions. If a build fails due to transient issues, rerun from failed (artifacts from successful builds are retained).
+
+1. Once all builds complete a [draft release](https://github.com/SimpleITK/SimpleITKRInstaller/releases) is created automatically. Verify the expected binary packages are present, test them (download, unzip, rename, install), then publish the release.
+
+1. Delete the short-lived branch:
 
-1. Commit and push changes:
-
     ```
-    git commit -am "Update SimpleITK release"
-    git push origin updateRelease
+    git push https://github.com/SimpleITK/SimpleITKRInstaller.git --delete release-v3.0.0b1
+    git branch -d release-v3.0.0b1
     ```
 
-1. On GitHub create a PR, see that all tests pass and binary artifacts are created successfuly. Merge into main.
+---
+
+## Releasing a patch on an old maintenance series (e.g. v2.5.7 after main is at v3.0.0)
+
+Old maintenance series have a long-lived `release-major.minor` branch as a safe PR target so that old-series patches cannot accidentally be merged into `main`.
+
+### Creating a maintenance branch (one time per series)
+
+If the `release-2.5` branch does not yet exist, cut it from the last stable tag of that series (e.g. `v2.5.6`):
 
-1. Update local `main` from the remote and check out the `main` branch. Tag it using the **exact tag** you listed in the `SITK_TARGET` and push the tag to this repository.
+```
+git fetch --tags https://github.com/SimpleITK/SimpleITKRInstaller.git
+git checkout v2.5.6
+git checkout -b release-2.5
+git push https://github.com/SimpleITK/SimpleITKRInstaller.git release-2.5
+```
 
-   ```
-   git tag v2.5.5
-   git push https://github.com/SimpleITK/SimpleITKRInstaller.git v2.5.5
-   ```
+### Releasing a patch
 
-1. Monitor the build process, https://github.com/SimpleITK/SimpleITKRInstaller/actions. If a build fails due to transient issues, rerun from failed (binary artifacts created for successful builds are retained across reruns). 
+1. Create a short-lived branch off the maintenance branch:
 
-1. Once all builds complete successfully a [draft release](https://github.com/SimpleITK/SimpleITKRInstaller/releases) is automatically created. Verify that the expected binary packages are available as release artifacts and test them (download, unzip, rename and install).
+    ```
+    git checkout release-2.5
+    git pull https://github.com/SimpleITK/SimpleITKRInstaller.git release-2.5
+    git checkout -b release-v2.5.7
+    ```
+
+    > **Note**: this branch carries the CI from `release-2.5`, not current `main`. If CI fixes are needed, apply them to `release-2.5` first.
 
-1. Edit and publish the release. Check that the binary distribution is working as expected via the r-universe distribution of the foyer package (follow the usage instructions provided in the GitHub release notes).
+1. Update the `DESCRIPTION` file: change `SITK_TARGET` to `v2.5.7` and run the `sitk_r_version_date.sh` script.
+
+1. Commit and push:
+
+    ```
+    git commit -am "Update SimpleITK to v2.5.7"
+    git push https://github.com/SimpleITK/SimpleITKRInstaller.git release-v2.5.7
+    ```
+
+1. On GitHub open a PR **targeting `release-2.5`** (not `main`). Verify all builds pass and artifacts are created. Merge into `release-2.5`.
+
+1. Pull the updated maintenance branch and tag its HEAD:
+
+    ```
+    git checkout release-2.5
+    git pull https://github.com/SimpleITK/SimpleITKRInstaller.git release-2.5
+    git tag -a v2.5.7 -m "Release v2.5.7"
+    git push https://github.com/SimpleITK/SimpleITKRInstaller.git v2.5.7
+    ```
+
+1. Monitor, verify artifacts, and publish the release.
+
+1. Delete the short-lived branch:
+
+    ```
+    git push https://github.com/SimpleITK/SimpleITKRInstaller.git --delete release-v2.5.7
+    git branch -d release-v2.5.7
+    ```