ci: add release workflow

.github/workflows/release.yml

@@ -0,0 +1,85 @@
+# A full semantic-version tag is version-specific release history. After the complete action test
+# matrix passes, publish that release and move only its matching major tag so `@v1` users receive
+# the new compatible version. The tagged commit must already be part of main.
+
+name: release
+
+on:
+  push:
+    tags: ["v*.*.*"]
+
+permissions:
+  contents: read
+
+concurrency:
+  group: release-${{ github.ref }}
+
+jobs:
+  validate:
+    runs-on: ubuntu-latest
+    outputs:
+      major: ${{ steps.version.outputs.major }}
+      release-commit: ${{ steps.version.outputs.release-commit }}
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Validate release tag
+        id: version
+        shell: bash
+        run: |
+          set -euo pipefail
+          tag="$GITHUB_REF_NAME"
+          if [[ ! "$tag" =~ ^v([0-9]+)\.([0-9]+)\.([0-9]+)$ ]]; then
+            echo "release tag must be an exact version such as v1.1.0" >&2
+            exit 1
+          fi
+
+          major="v${BASH_REMATCH[1]}"
+          release_commit="$(git rev-parse "$tag^{}")"
+          git fetch origin main --no-tags
+          if ! git merge-base --is-ancestor "$release_commit" origin/main; then
+            echo "$tag does not point to a commit on main" >&2
+            exit 1
+          fi
+
+          echo "major=$major" >>"$GITHUB_OUTPUT"
+          echo "release-commit=$release_commit" >>"$GITHUB_OUTPUT"
+
+  test:
+    needs: validate
+    uses: ./.github/workflows/test.yml
+
+  release:
+    needs: [validate, test]
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Publish versioned release
+        env:
+          GH_TOKEN: ${{ github.token }}
+        run: |
+          set -euo pipefail
+          if ! gh release view "$GITHUB_REF_NAME" >/dev/null 2>&1; then
+            gh release create "$GITHUB_REF_NAME" \
+              --verify-tag \
+              --title "$GITHUB_REF_NAME" \
+              --generate-notes
+          fi
+
+      - name: Move major tag
+        env:
+          MAJOR_TAG: ${{ needs.validate.outputs.major }}
+          RELEASE_COMMIT: ${{ needs.validate.outputs.release-commit }}
+        run: |
+          set -euo pipefail
+          git config user.name "github-actions[bot]"
+          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
+          git tag -fa "$MAJOR_TAG" "$RELEASE_COMMIT" -m "Update $MAJOR_TAG to $GITHUB_REF_NAME"
+          git push origin "refs/tags/$MAJOR_TAG" --force

.github/workflows/test.yml

@@ -14,25 +14,57 @@ on:
   push:
     branches: [main]
   pull_request:
+  workflow_call:
 
 env:
   SOTTO_TEST_VERSION: v0.4.0
 
 jobs:
   reject-invalid-version:
+    name: reject-invalid-version (${{ matrix.name }})
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - name: empty
+            version: ""
+          - name: floating
+            version: latest
+          - name: partial
+            version: v0.4
+          - name: prerelease
+            version: v0.4.0-rc.1
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - name: Reject an unpinned version
+      - name: Reject invalid version
         id: invalid
         continue-on-error: true
         uses: ./
         with:
-          sotto-version: latest
+          sotto-version: ${{ matrix.version }}
       - name: Check rejection
         if: steps.invalid.outcome != 'failure'
+        env:
+          REJECTED_VERSION: ${{ matrix.version }}
+        run: |
+          echo "expected the action to reject '$REJECTED_VERSION'" >&2
+          exit 1
+
+  reject-missing-release:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Reject a version with no release
+        id: missing
+        continue-on-error: true
+        uses: ./
+        with:
+          sotto-version: v999.999.999
+      - name: Check rejection
+        if: steps.missing.outcome != 'failure'
         run: |
-          echo "expected the action to reject an unpinned version" >&2
+          echo "expected the action to reject a version with no release" >&2
           exit 1
 
   install-and-verify:

README.md

@@ -55,3 +55,19 @@ Give the step an `id` to use the resolved installation details in later steps:
 This action is tagged independently of the `sotto` CLI's own version (`v0.1.0`, `v0.2.0`, ...) -
 `sotto-action@v1` and `sotto-version: v0.4.0` are two unrelated version numbers. See
 [getsotto/sotto#67](https://github.com/getsotto/sotto/issues/67) for why.
+
+Use `@v1` to receive backwards-compatible action updates, a full tag such as `@v1.1.0` to pin a
+version-specific action release, or a full commit SHA for the strongest workflow pinning.
+
+## Releasing
+
+Maintainers release the action by pushing an exact semantic-version tag from `main`:
+
+```sh
+git tag -a v1.1.0 -m "v1.1.0"
+git push origin v1.1.0
+```
+
+The release workflow validates the tag, runs the complete target matrix, creates the versioned
+`v1.1.0` GitHub release, then moves the compatible major tag (`v1`) to the same commit. Invalid tags
+and tags whose commit is not on `main` fail without publishing or moving the major tag.