diff --git a/.gitea/workflows/quality.yaml b/.gitea/workflows/quality.yaml
index 861d22c..7768e52 100644
--- a/.gitea/workflows/quality.yaml
+++ b/.gitea/workflows/quality.yaml
@@ -46,7 +46,9 @@ jobs:
       - if: ${{ inputs.is_pull_request == false }}
         uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
-          fetch-depth: 2
+          # Full history: before_sha may be many commits behind the new tip
+          # (multi-commit pushes) and must exist locally for git diff.
+          fetch-depth: 0
       - id: detect
         name: Detect changed paths per module
         env:
@@ -80,7 +82,14 @@ jobs:
           else
             after="${HEAD_SHA:-$(git rev-parse HEAD)}"
             before="$BEFORE_SHA"
+            # Guard: a stale/unresolvable before_sha must not fail the pipeline.
             if [ -n "$before" ] && [ "$before" != "0000000000000000000000000000000000000000" ]; then
+              if ! git cat-file -e "$before^{commit}" 2>/dev/null; then
+                echo "::warning::before_sha $before not resolvable, falling back to HEAD~1"
+                before=""
+              fi
+            fi
+            if [ -n "$before" ]; then
               FILES="$(git diff --name-only "$before" "$after")"
             elif git rev-parse --verify HEAD~1 >/dev/null 2>&1; then
               FILES="$(git diff --name-only HEAD~1 HEAD)"