diff --git a/.github/workflows/package.yml b/.github/workflows/package.yml
index 722b45c..b257743 100644
--- a/.github/workflows/package.yml
+++ b/.github/workflows/package.yml
@@ -43,6 +43,11 @@ on:
           - testpypi
           - pypi
         default: testpypi
+      release_tag:
+        description: "Annotated version tag to publish when dispatching from the default branch"
+        required: false
+        type: string
+        default: ""
 
 permissions:
   contents: read
@@ -61,11 +66,15 @@ jobs:
     timeout-minutes: 10
     outputs:
       version: ${{ steps.metadata.outputs.version }}
+      source_commit: ${{ steps.metadata.outputs.source_commit }}
+      release_tag: ${{ steps.metadata.outputs.release_tag }}
+      source_ref_type: ${{ steps.metadata.outputs.source_ref_type }}
     steps:
       - name: Check out source
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
           fetch-depth: 0
+          ref: ${{ inputs.release_tag || github.ref }}
 
       - name: Set up Python
         uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97 # v7.0.0
@@ -74,18 +83,44 @@ jobs:
 
       - name: Read package version
         id: metadata
-        run: echo "version=$(tr -d '\\r\\n' < VERSION)" >> "$GITHUB_OUTPUT"
+        env:
+          REQUESTED_RELEASE_TAG: ${{ inputs.release_tag || '' }}
+        run: |
+          version="$(tr -d '\\r\\n' < VERSION)"
+          release_tag="$REQUESTED_RELEASE_TAG"
+          if [[ -n "$release_tag" ]]; then
+            source_ref_type=tag
+            source_commit="$(git rev-parse --verify "refs/tags/$release_tag^{}")"
+          else
+            source_ref_type="$GITHUB_REF_TYPE"
+            source_commit="$GITHUB_SHA"
+            if [[ "$source_ref_type" == tag ]]; then
+              release_tag="$GITHUB_REF_NAME"
+            fi
+          fi
+          echo "version=$version" >> "$GITHUB_OUTPUT"
+          echo "source_commit=$source_commit" >> "$GITHUB_OUTPUT"
+          echo "release_tag=$release_tag" >> "$GITHUB_OUTPUT"
+          echo "source_ref_type=$source_ref_type" >> "$GITHUB_OUTPUT"
 
       - name: Validate release ref
         env:
           PUBLISH_TARGET: ${{ inputs.publish_target || '' }}
+          REQUESTED_RELEASE_TAG: ${{ inputs.release_tag || '' }}
+          SOURCE_REF_TYPE: ${{ steps.metadata.outputs.source_ref_type }}
+          RELEASE_TAG: ${{ steps.metadata.outputs.release_tag }}
+          VERSION: ${{ steps.metadata.outputs.version }}
         run: |
-          if [[ "$GITHUB_REF_TYPE" == "tag" && "$GITHUB_REF_NAME" != "v${{ steps.metadata.outputs.version }}" ]]; then
-            echo "Release tag must be v${{ steps.metadata.outputs.version }}; got $GITHUB_REF_NAME" >&2
+          if [[ "$SOURCE_REF_TYPE" == "tag" && "$RELEASE_TAG" != "v$VERSION" ]]; then
+            echo "Release tag must be v$VERSION; got $RELEASE_TAG" >&2
             exit 1
           fi
-          if [[ "$PUBLISH_TARGET" == "pypi" && "$GITHUB_REF_TYPE" != "tag" ]]; then
-            echo "PyPI publication requires dispatching this workflow from the matching version tag." >&2
+          if [[ "$PUBLISH_TARGET" == "pypi" && "$SOURCE_REF_TYPE" != "tag" ]]; then
+            echo "PyPI publication requires a matching version tag." >&2
+            exit 1
+          fi
+          if [[ "$PUBLISH_TARGET" == "pypi" && "$GITHUB_EVENT_NAME" == workflow_dispatch && -z "$REQUESTED_RELEASE_TAG" ]]; then
+            echo "Manual PyPI publication requires the release_tag input." >&2
             exit 1
           fi
 
@@ -93,9 +128,9 @@ jobs:
         run: python scripts/validate_changelog.py
 
       - name: Validate tagged release notes
-        if: ${{ github.ref_type == 'tag' }}
+        if: ${{ steps.metadata.outputs.source_ref_type == 'tag' }}
         env:
-          RELEASE_TAG: ${{ github.ref_name }}
+          RELEASE_TAG: ${{ steps.metadata.outputs.release_tag }}
         run: python scripts/validate_release_ref.py
 
       - name: Prepare clean artifact destination
@@ -111,12 +146,13 @@ jobs:
           # Keep the reproducibility input numeric; push-event timestamps are
           # ISO-8601 strings and are not accepted by wheel/build backends.
           SOURCE_DATE_EPOCH: '0'
+          SOURCE_COMMIT: ${{ steps.metadata.outputs.source_commit }}
         run: |
           rm -rf dist-a dist-b "$RUNNER_TEMP/base-cli-build-a" "$RUNNER_TEMP/base-cli-build-b"
           mkdir -p dist-a dist-b
           mkdir -p "$RUNNER_TEMP/base-cli-build-a" "$RUNNER_TEMP/base-cli-build-b"
-          git archive "$GITHUB_SHA" | tar -x -C "$RUNNER_TEMP/base-cli-build-a"
-          git archive "$GITHUB_SHA" | tar -x -C "$RUNNER_TEMP/base-cli-build-b"
+          git archive "$SOURCE_COMMIT" | tar -x -C "$RUNNER_TEMP/base-cli-build-a"
+          git archive "$SOURCE_COMMIT" | tar -x -C "$RUNNER_TEMP/base-cli-build-b"
           (cd "$RUNNER_TEMP/base-cli-build-a" && python -m build --sdist --wheel --outdir "$GITHUB_WORKSPACE/dist-a")
           (cd "$RUNNER_TEMP/base-cli-build-b" && python -m build --sdist --wheel --outdir "$GITHUB_WORKSPACE/dist-b")
           python - <<'PY'
@@ -155,13 +191,13 @@ jobs:
 
       - name: Generate release checksums and SPDX SBOM
         env:
-          SOURCE_REVISION: ${{ github.sha }}
+          SOURCE_REVISION: ${{ steps.metadata.outputs.source_commit }}
           SOURCE_DATE_EPOCH: '0'
         run: python scripts/generate_release_metadata.py dist
 
       - name: Validate release checksums and SPDX SBOM
         env:
-          SOURCE_REVISION: ${{ github.sha }}
+          SOURCE_REVISION: ${{ steps.metadata.outputs.source_commit }}
         run: python scripts/validate_release_metadata.py dist
 
       - name: Upload reviewed distributions
@@ -199,6 +235,7 @@ jobs:
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
           fetch-depth: 0
+          ref: ${{ needs.build.outputs.source_commit }}
 
       - name: Set up Python
         uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97 # v7.0.0
@@ -250,6 +287,7 @@ jobs:
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
           fetch-depth: 0
+          ref: ${{ needs.build.outputs.source_commit }}
 
       - name: Fetch trusted main history
         run: git fetch --no-tags --prune origin "refs/heads/main:refs/remotes/origin/main"
@@ -257,7 +295,15 @@ jobs:
       - name: Verify release provenance
         env:
           PUBLISH_TARGET: ${{ inputs.publish_target || '' }}
-        run: python scripts/validate_release_provenance.py
+          SOURCE_REF_TYPE: ${{ needs.build.outputs.source_ref_type }}
+          RELEASE_TAG: ${{ needs.build.outputs.release_tag }}
+          SOURCE_COMMIT: ${{ needs.build.outputs.source_commit }}
+        run: |
+          python scripts/validate_release_provenance.py \
+            --ref-type "$SOURCE_REF_TYPE" \
+            --tag "$RELEASE_TAG" \
+            --publish-target "$PUBLISH_TARGET" \
+            --source-commit "$SOURCE_COMMIT"
 
   publish:
     name: Publish reviewed distribution
@@ -328,7 +374,7 @@ jobs:
   release:
     name: Create GitHub Release
     needs: [build, smoke, provenance, publish, attest]
-    if: ${{ github.event_name == 'push' && github.ref_type == 'tag' }}
+    if: ${{ (github.event_name == 'push' && github.ref_type == 'tag') || (github.event_name == 'workflow_dispatch' && inputs.publish_target == 'pypi' && inputs.release_tag != '') }}
     runs-on: ubuntu-latest
     timeout-minutes: 10
     permissions:
@@ -337,6 +383,9 @@ jobs:
     steps:
       - name: Check out the tag source
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          fetch-depth: 0
+          ref: ${{ needs.build.outputs.source_commit }}
 
       - name: Set up Python
         uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97 # v7.0.0
@@ -358,13 +407,17 @@ jobs:
       - name: Verify and create immutable GitHub Release
         env:
           GH_TOKEN: ${{ github.token }}
+          SOURCE_REVISION: ${{ needs.build.outputs.source_commit }}
+          RELEASE_TAG: ${{ needs.build.outputs.release_tag }}
+          SOURCE_COMMIT: ${{ needs.build.outputs.source_commit }}
         run: |
           set -euo pipefail
-          tag="$GITHUB_REF_NAME"
+          tag="$RELEASE_TAG"
+          source_commit="$SOURCE_COMMIT"
           assets=(dist/*.whl dist/*.tar.gz dist/SHA256SUMS dist/SBOM.spdx.json dist/RELEASE-BOM-ROW.json)
           tag_commit="$(gh api "repos/$GITHUB_REPOSITORY/commits/$tag" --jq .sha)"
-          if [[ "$tag_commit" != "$GITHUB_SHA" ]]; then
-            echo "Release tag $tag resolves to $tag_commit, not reviewed commit $GITHUB_SHA." >&2
+          if [[ "$tag_commit" != "$source_commit" ]]; then
+            echo "Release tag $tag resolves to $tag_commit, not reviewed commit $source_commit." >&2
             exit 1
           fi
 
@@ -424,7 +477,7 @@ jobs:
               --release-json "$release_json" \
               --version-file VERSION \
               --tag "$tag" \
-              --source-commit "$GITHUB_SHA" \
+              --source-commit "$source_commit" \
               --resolved-tag-commit "$tag_commit"
           }
 
diff --git a/tests/test_package_workflow.py b/tests/test_package_workflow.py
index 71de8e8..e4ad821 100644
--- a/tests/test_package_workflow.py
+++ b/tests/test_package_workflow.py
@@ -12,6 +12,18 @@ def test_package_workflow_uses_numeric_reproducibility_epoch() -> None:
     assert workflow.count("SOURCE_DATE_EPOCH: '0'") == 2
 
 
+def test_package_workflow_can_recover_an_immutable_tag_from_default_branch() -> None:
+    workflow = (Path(__file__).resolve().parents[1] / ".github/workflows/package.yml").read_text(encoding="utf-8")
+
+    assert "release_tag:" in workflow
+    assert "ref: ${{ inputs.release_tag || github.ref }}" in workflow
+    assert "source_commit: ${{ steps.metadata.outputs.source_commit }}" in workflow
+    assert "SOURCE_COMMIT: ${{ steps.metadata.outputs.source_commit }}" in workflow
+    assert 'git archive "$SOURCE_COMMIT"' in workflow
+    assert "Manual PyPI publication requires the release_tag input." in workflow
+    assert '--source-commit "$SOURCE_COMMIT"' in workflow
+
+
 def test_package_workflow_does_not_replace_published_release_assets() -> None:
     workflow = (Path(__file__).resolve().parents[1] / ".github/workflows/package.yml").read_text(encoding="utf-8")
     verifier = (Path(__file__).resolve().parents[1] / "scripts/verify_release_assets.py").read_text(encoding="utf-8")
@@ -23,6 +35,7 @@ def test_package_workflow_does_not_replace_published_release_assets() -> None:
     assert "gh attestation verify" in workflow
     assert '--source-digest "$GITHUB_SHA"' in workflow
     assert '--source-ref "$GITHUB_REF"' in workflow
+    assert '--source-commit "$source_commit"' in workflow
     assert "--clobber" not in workflow