fix(backup): ignore interrupted shard temps

internal/backup/backup.go

@@ -760,3 +760,25 @@ func removeStaleShards(repo string, shards []ShardEntry) error {
 	}
 	return nil
 }
+
+func removeTempShardFiles(repo string) error {
+	for _, rootName := range []string{"data", "checkpoints"} {
+		root := filepath.Join(repo, rootName)
+		if _, err := os.Stat(root); os.IsNotExist(err) {
+			continue
+		}
+		if err := filepath.WalkDir(root, func(path string, d os.DirEntry, err error) error {
+			if err != nil || d == nil || d.IsDir() {
+				return err
+			}
+			name := d.Name()
+			if strings.HasPrefix(name, ".shard-") && strings.HasSuffix(name, ".age") {
+				return os.Remove(path) //nolint:gosec // repo-owned temp shard paths come from WalkDir below configured backup roots.
+			}
+			return nil
+		}); err != nil {
+			return err
+		}
+	}
+	return nil
+}

internal/backup/backup_test.go

@@ -141,6 +141,25 @@ func TestPushCheckpointWritesIncompleteManifestOutsideMainSnapshot(t *testing.T)
 	}
 }
 
+func TestCommitAndPushRemovesInterruptedShardTemps(t *testing.T) {
+	ctx, repo, config, _ := initTestBackup(t)
+	temp := filepath.Join(repo, "checkpoints", "gmail", "acct", "run-one", "messages", ".shard-interrupted.age")
+	if err := os.MkdirAll(filepath.Dir(temp), 0o700); err != nil {
+		t.Fatalf("MkdirAll: %v", err)
+	}
+	if err := os.WriteFile(temp, []byte("partial ciphertext"), 0o600); err != nil {
+		t.Fatalf("WriteFile: %v", err)
+	}
+
+	pushSingleShard(t, ctx, config, mustGmailMessageShard(t, "data/gmail/acct/messages/2026/04/part-0001.jsonl.gz.age", []map[string]string{{"id": "m1", "raw": "final"}}))
+	if _, err := os.Stat(temp); !os.IsNotExist(err) {
+		t.Fatalf("temp shard should be removed before commit: %v", err)
+	}
+	if err := git(ctx, repo, "ls-files", "--error-unmatch", "checkpoints/gmail/acct/run-one/messages/.shard-interrupted.age"); err == nil {
+		t.Fatal("temp shard was committed")
+	}
+}
+
 func TestCatAndDecryptSnapshotVerifyPlaintext(t *testing.T) {
 	ctx, repo, config, _ := initTestBackup(t)
 	shardPath := "data/gmail/acct/messages/2026/04/part-0001.jsonl.gz.age"

internal/backup/git.go

@@ -54,6 +54,9 @@ func ensureRepo(ctx context.Context, cfg Config) error {
 }
 
 func commitAndPush(ctx context.Context, cfg Config, message string, push bool) (bool, error) {
+	if err := removeTempShardFiles(cfg.Repo); err != nil {
+		return false, err
+	}
 	if err := git(ctx, cfg.Repo, "add", "."); err != nil {
 		return false, err
 	}