fix(gitlab): pin commit statuses to the same pipeline via pipeline_id caching

pkg/apis/pipelinesascode/keys/keys.go

@@ -48,6 +48,7 @@ const (
 	OriginalPRName         = pipelinesascode.GroupName + "/original-prname"
 	GitAuthSecret          = pipelinesascode.GroupName + "/git-auth-secret"
 	CheckRunID             = pipelinesascode.GroupName + "/check-run-id"
+	GitLabPipelineID       = pipelinesascode.GroupName + "/gitlab-pipeline-id"
 	OnEvent                = pipelinesascode.GroupName + "/on-event"
 	OnComment              = pipelinesascode.GroupName + "/on-comment"
 	OnTargetBranch         = pipelinesascode.GroupName + "/on-target-branch"

pkg/provider/gitlab/gitlab.go

@@ -12,6 +12,8 @@ import (
 	"strconv"
 	"strings"
 
+	"github.com/openshift-pipelines/pipelines-as-code/pkg/action"
+	"github.com/openshift-pipelines/pipelines-as-code/pkg/apis/pipelinesascode/keys"
 	"github.com/openshift-pipelines/pipelines-as-code/pkg/apis/pipelinesascode/v1alpha1"
 	"github.com/openshift-pipelines/pipelines-as-code/pkg/changedfiles"
 	"github.com/openshift-pipelines/pipelines-as-code/pkg/events"
@@ -354,22 +356,42 @@ func (v *Provider) CreateStatus(ctx context.Context, event *info.Event, statusOp
 		Context:     gitlab.Ptr(contextName),
 	}
 
+	// Read a previously stored pipeline ID from PipelineRun annotations so
+	// that all commit statuses land in the same GitLab pipeline instead of
+	// GitLab potentially auto-creating a new "external" pipeline mid-stream.
+	if statusOpts.PipelineRun != nil {
+		if id, ok := statusOpts.PipelineRun.GetAnnotations()[keys.GitLabPipelineID]; ok {
+			pid, err := strconv.ParseInt(id, 10, 64)
+			if err == nil {
+				opt.PipelineID = gitlab.Ptr(pid)
+			}
+		}
+	}
+
 	// In case we have access, set the status. Typically, on a Merge Request (MR)
 	// from a fork in an upstream repository, the token needs to have write access
 	// to the fork repository in order to create a status. However, the token set on the
 	// Repository CR usually doesn't have such broad access, preventing from creating
 	// a status comment on it.
 	// This would work on a push or an MR from a branch within the same repo.
 	// Ignoring errors because of the write access issues,
-	_, _, err := v.Client().Commits.SetCommitStatus(event.SourceProjectID, event.SHA, opt)
+	commitStatus, _, err := v.Client().Commits.SetCommitStatus(event.SourceProjectID, event.SHA, opt)
 	if err != nil {
 		v.Logger.Debugf("cannot set status with the GitLab token on the source project: %v", err)
 	} else {
+		v.patchPipelineIDAnnotation(ctx, statusOpts, commitStatus)
 		// we managed to set the status on the source repo, all good we are done
 		v.Logger.Debugf("created commit status on source project ID %d", event.TargetProjectID)
 		return nil
 	}
-	if _, _, err = v.Client().Commits.SetCommitStatus(event.TargetProjectID, event.SHA, opt); err == nil {
+	// Clear pipeline ID when falling back to the target project — the cached
+	// ID belongs to the source project's pipeline namespace and is invalid on
+	// a different project (fork MR scenario).
+	if event.SourceProjectID != event.TargetProjectID {
+		opt.PipelineID = nil
+	}
+	if commitStatus, _, err = v.Client().Commits.SetCommitStatus(event.TargetProjectID, event.SHA, opt); err == nil {
+		v.patchPipelineIDAnnotation(ctx, statusOpts, commitStatus)
 		v.Logger.Debugf("created commit status on target project ID %d", event.TargetProjectID)
 		// we managed to set the status on the target repo, all good we are done
 		return nil
@@ -860,3 +882,32 @@ func (v *Provider) formatPipelineComment(sha string, status providerstatus.Statu
 	return fmt.Sprintf("%s **%s: %s/%s for %s**\n\n%s\n\n<small>Full log available [here](%s)</small>",
 		emoji, status.Title, v.pacInfo.ApplicationName, status.OriginalPipelineRunName, sha, status.Text, status.DetailsURL)
 }
+
+// patchPipelineIDAnnotation stores the GitLab pipeline ID from a successful
+// SetCommitStatus response as a PipelineRun annotation. This allows the
+// reconciler (which creates a new Provider instance) to read it back and
+// pass it on subsequent status updates, keeping all statuses in the same
+// GitLab pipeline.
+func (v *Provider) patchPipelineIDAnnotation(ctx context.Context, statusOpts providerstatus.StatusOpts, cs *gitlab.CommitStatus) {
+	if cs == nil || cs.PipelineID == 0 {
+		return
+	}
+	pr := statusOpts.PipelineRun
+	if pr == nil || (pr.GetName() == "" && pr.GetGenerateName() == "") {
+		return
+	}
+	// Skip if annotation is already set — avoid unnecessary patches.
+	if _, ok := pr.GetAnnotations()[keys.GitLabPipelineID]; ok {
+		return
+	}
+	mergePatch := map[string]any{
+		"metadata": map[string]any{
+			"annotations": map[string]string{
+				keys.GitLabPipelineID: strconv.FormatInt(cs.PipelineID, 10),
+			},
+		},
+	}
+	if _, err := action.PatchPipelineRun(ctx, v.Logger, "gitlabPipelineID", v.run.Clients.Tekton, pr, mergePatch); err != nil {
+		v.Logger.Debugf("failed to patch pipelinerun with gitlab pipeline ID: %v", err)
+	}
+}