ci: release workflow auto-creates publish branch

.github/workflows/reusable-publish-release.yml

@@ -172,12 +172,19 @@ jobs:
           done < "$RUNNER_TEMP/tags.txt"
 
       # Copy the source channel onto the published channel(s), preserving the others, then guard that
-      # every tag the published feed references exists before pushing.
+      # every tag the published feed references exists before pushing. On the first release the publish
+      # branch doesn't exist yet, so seed the worktree from the released commit and let the final push
+      # create it.
       - name: Publish to the publish branch
         run: |
           set -euo pipefail
-          git fetch origin "${{ inputs.publish-branch }}:refs/remotes/origin/${{ inputs.publish-branch }}"
-          git worktree add --detach _publish "origin/${{ inputs.publish-branch }}"
+          if git ls-remote --exit-code --heads origin "${{ inputs.publish-branch }}" >/dev/null 2>&1; then
+            git fetch origin "${{ inputs.publish-branch }}:refs/remotes/origin/${{ inputs.publish-branch }}"
+            git worktree add --detach _publish "origin/${{ inputs.publish-branch }}"
+          else
+            echo "Publish branch '${{ inputs.publish-branch }}' doesn't exist yet — bootstrapping it from the released commit."
+            git worktree add --detach _publish HEAD
+          fi
           rsync -a --delete \
             --exclude '.git' --exclude '_publish' --exclude '_depctrl' \
             --exclude 'ctrf' --exclude 'types' --exclude 'build' \

README.md

@@ -823,7 +823,7 @@ DependencyControl's own feed URL served from `master` through v0.6.x; from v0.7.
 
 ### Using the workflows in your own package
 
-1. **Set up the branches.** Make your dev branch the default and create a publish branch. In your feed, give each package a single dev channel (its name is the `source-channel` input, default `main`); the release workflow creates the published channels.
+1. **Set up the branches.** Make your dev branch the default. The first release creates the publish branch for you, so you needn't create it by hand. In your feed, give each package a single dev channel (its name is the `source-channel` input, default `main`); the release workflow creates the published channels.
 2. **Add two thin caller workflows** that pin a DependencyControl version and pass your layout. A publish caller (`.github/workflows/release.yml`):
 
    ```yaml