Fix multiple code review issues: dedup splitKey, fix merge bug, remove dead code

- Extract triplicated splitKey into shared pkg/reconciler/internal package
  using strings.Cut and removing the unnecessary error return
- Fix resolver merge bug: attemptMerge was using treeA.Hash as the merge
  commit tree, silently dropping all of branch B's changes. Now builds a
  proper merged tree that applies B's non-conflicting changes onto A's tree
- Replace hand-rolled nestedFieldNoCopy/unstructuredNestedStringMap with
  k8s.io/apimachinery's unstructured.NestedStringMap stdlib equivalent
- Hoist branch listing out of per-refspec loop in updateBranches to avoid
  redundant API calls
- Add not-found handling in all three reconcilers so deleted resources
  don't cause infinite requeue loops
- Fix client.Get() to use checked type assertion with a clear panic message
  instead of an opaque nil-pointer dereference
- Remove dead code: unused addDefaultingFuncs wrapper, unused context
  injection in push controller setup

https://claude.ai/code/session_01634JRpHEoM9FzuBjZ7qHcY

pkg/reconciler/sync/sync.go

@@ -3,9 +3,11 @@ package sync
 import (
 	"context"
 	"fmt"
+
 	"github.com/go-git/go-git/v5"
 	"github.com/go-git/go-git/v5/plumbing"
 	"github.com/go-git/go-git/v5/storage/memory"
+	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/client-go/dynamic"
@@ -14,6 +16,7 @@ import (
 
 	gitv1alpha1 "github.com/imjasonh/git-k8s/pkg/apis/git/v1alpha1"
 	gitclient "github.com/imjasonh/git-k8s/pkg/client"
+	"github.com/imjasonh/git-k8s/pkg/reconciler/internal"
 )
 
 // Reconciler implements the reconcile logic for GitRepoSync.
@@ -26,13 +29,14 @@ type Reconciler struct {
 func (r *Reconciler) Reconcile(ctx context.Context, key string) error {
 	logger := logging.FromContext(ctx)
 
-	namespace, name, err := splitKey(key)
-	if err != nil {
-		return err
-	}
+	namespace, name := internal.SplitKey(key)
 
 	// Fetch the GitRepoSync resource.
 	syncObj, err := r.gitClient.GitRepoSyncs(namespace).Get(ctx, name, metav1.GetOptions{})
+	if apierrors.IsNotFound(err) {
+		logger.Debugf("GitRepoSync %s/%s no longer exists", namespace, name)
+		return nil
+	}
 	if err != nil {
 		return fmt.Errorf("getting GitRepoSync %s/%s: %w", namespace, name, err)
 	}
@@ -208,15 +212,6 @@ func (r *Reconciler) updateSyncStatus(ctx context.Context, syncObj *gitv1alpha1.
 	return err
 }
 
-func splitKey(key string) (string, string, error) {
-	for i := range key {
-		if key[i] == '/' {
-			return key[:i], key[i+1:], nil
-		}
-	}
-	return "", key, nil
-}
-
 // Ensure Reconciler implements the reconciler interface.
 var _ reconciler.LeaderAware = (*Reconciler)(nil)
 
@@ -226,4 +221,3 @@ func (r *Reconciler) Promote(bkt reconciler.Bucket, enq func(reconciler.Bucket,
 
 func (r *Reconciler) Demote(bkt reconciler.Bucket) {
 }
-

pkg/reconciler/sync/sync_test.go

@@ -1,54 +1 @@
 package sync
-
-import (
-	"testing"
-)
-
-func TestSplitKey(t *testing.T) {
-	tests := []struct {
-		key      string
-		wantNS   string
-		wantName string
-	}{
-		{
-			key:      "default/my-sync",
-			wantNS:   "default",
-			wantName: "my-sync",
-		},
-		{
-			key:      "git-system/sync-controller",
-			wantNS:   "git-system",
-			wantName: "sync-controller",
-		},
-		{
-			key:      "just-name",
-			wantNS:   "",
-			wantName: "just-name",
-		},
-		{
-			key:      "",
-			wantNS:   "",
-			wantName: "",
-		},
-		{
-			key:      "ns/name/extra",
-			wantNS:   "ns",
-			wantName: "name/extra",
-		},
-	}
-
-	for _, tt := range tests {
-		t.Run(tt.key, func(t *testing.T) {
-			ns, name, err := splitKey(tt.key)
-			if err != nil {
-				t.Fatalf("splitKey(%q) error = %v", tt.key, err)
-			}
-			if ns != tt.wantNS {
-				t.Errorf("namespace = %q, want %q", ns, tt.wantNS)
-			}
-			if name != tt.wantName {
-				t.Errorf("name = %q, want %q", name, tt.wantName)
-			}
-		})
-	}
-}