fix: address PR #32 review comments

- Use github.event.before SHA instead of HEAD~1 for reliable version
  diff across multi-commit pushes and merges.
- Use fetch-depth: 0 to ensure full history is available.
- Check remote tags via git ls-remote before creating, and handle
  concurrent tag creation gracefully.
- Fix misleading comment about cargo check updating Cargo.lock.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: mikkeldamsgaard

.claude/commands/release.md

@@ -28,7 +28,7 @@ Once confirmed:
 
 1. Fetch origin and create a branch: `release/vX.Y.Z` from `origin/main`.
 2. Bump version in `Cargo.toml` (the `version = "..."` field under `[package]`).
-3. Run `cargo check` to update `Cargo.lock`.
+3. Run `cargo check` to ensure the project builds successfully after the version bump.
 4. Update `CHANGELOG.md`:
    - Move everything under `## [Unreleased]` into a new `## [X.Y.Z] - YYYY-MM-DD` section (use today's date).
    - Leave `## [Unreleased]` empty (with just the heading).

.github/workflows/auto-tag.yml

@@ -12,12 +12,12 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          fetch-depth: 2
+          fetch-depth: 0
       - name: Check for version bump
         id: version
         run: |
           CURRENT=$(grep '^version' Cargo.toml | head -1 | sed 's/.*"\(.*\)"/\1/')
-          PREVIOUS=$(git show HEAD~1:Cargo.toml | grep '^version' | head -1 | sed 's/.*"\(.*\)"/\1/')
+          PREVIOUS=$(git show ${{ github.event.before }}:Cargo.toml | grep '^version' | head -1 | sed 's/.*"\(.*\)"/\1/')
           echo "current=$CURRENT" >> "$GITHUB_OUTPUT"
           echo "previous=$PREVIOUS" >> "$GITHUB_OUTPUT"
           if [ "$CURRENT" != "$PREVIOUS" ]; then
@@ -30,11 +30,22 @@ jobs:
         run: |
           VERSION="${{ steps.version.outputs.current }}"
           TAG="v${VERSION}"
+          if git ls-remote --tags origin "refs/tags/$TAG" | grep -q .; then
+            echo "Tag $TAG already exists on origin, skipping"
+            exit 0
+          fi
           if git rev-parse "$TAG" >/dev/null 2>&1; then
-            echo "Tag $TAG already exists, skipping"
+            echo "Tag $TAG already exists locally, skipping"
             exit 0
           fi
           git tag "$TAG"
-          git push origin "$TAG"
+          if ! git push origin "$TAG"; then
+            if git ls-remote --tags origin "refs/tags/$TAG" | grep -q .; then
+              echo "Tag $TAG was created concurrently on origin, skipping"
+              exit 0
+            fi
+            echo "Failed to push tag $TAG"
+            exit 1
+          fi
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}