diff --git a/internal/provider/rpm/rpm_meta_test.go b/internal/provider/rpm/rpm_meta_test.go
index 9a0c525..3e6d7b9 100644
--- a/internal/provider/rpm/rpm_meta_test.go
+++ b/internal/provider/rpm/rpm_meta_test.go
@@ -171,6 +171,31 @@ func TestRPMServeRepodata(t *testing.T) {
 	}
 }
 
+func TestRPMFullMetadataXML(t *testing.T) {
+	// A fully-populated entry exercises every optional-field branch in the
+	// primary/filelists/other XML generators.
+	metas := []provider.RPMMetadata{{
+		Name: "full", Epoch: 1, Version: "2.0", Release: "3", Arch: "x86_64",
+		Summary: "s", Description: "d", License: "MIT", Vendor: "acme",
+		Group: "System", BuildHost: "build.example.com", SourceRPM: "full-2.0.src.rpm",
+		URL: "https://example.com", Packager: "pkgr", ContentHash: "sha256:abc",
+		RPMSize: 100, InstalledSize: 200,
+		Requires:   []provider.RPMDep{{Name: "libc", Flags: "GE", Epoch: "0", Version: "2.0", Release: "1"}},
+		Provides:   []provider.RPMDep{{Name: "full", Flags: "EQ", Version: "2.0"}},
+		Files:      []provider.RPMFile{{Path: "/usr/bin/full", Type: "file"}, {Path: "/etc/full", Type: "dir"}},
+		Changelogs: []provider.RPMChangelog{{Author: "a", Date: 100, Text: "changed"}},
+	}}
+	for _, gen := range []func([]provider.RPMMetadata) []byte{generatePrimaryXMLGZ, generateFilelistsXMLGZ, generateOtherXMLGZ} {
+		zr, err := gzip.NewReader(bytes.NewReader(gen(metas)))
+		if err != nil {
+			t.Fatal(err)
+		}
+		if _, err := io.ReadAll(zr); err != nil {
+			t.Error(err)
+		}
+	}
+}
+
 func TestRPMPrimaryXMLContents(t *testing.T) {
 	// Exercise xmlEscape and dependency entry writing through the gzip'd XML.
 	metas := []provider.RPMMetadata{{
diff --git a/internal/proxy/engine_test.go b/internal/proxy/engine_test.go
index 6e42fb7..de4f73e 100644
--- a/internal/proxy/engine_test.go
+++ b/internal/proxy/engine_test.go
@@ -413,6 +413,44 @@ func TestRevalidationUpstreamError(t *testing.T) {
 	res.Reader.Close()
 }
 
+func TestTTLFor(t *testing.T) {
+	e := &Engine{}
+	if got := e.ttlFor(models.Remote{ImmutableTTL: 100}, ClassImmutable); got != 100*time.Second {
+		t.Errorf("immutable ttl = %v", got)
+	}
+	if got := e.ttlFor(models.Remote{ImmutableTTL: 0}, ClassImmutable); got != 0 {
+		t.Errorf("immutable ttl=0 (forever) = %v", got)
+	}
+	if got := e.ttlFor(models.Remote{MutableTTL: 50}, ClassMutable); got != 50*time.Second {
+		t.Errorf("mutable ttl = %v", got)
+	}
+}
+
+func TestHeadUpstreamStatusError(t *testing.T) {
+	requireStack(t)
+	r := seed(t, genericRemote("eng-head500"))
+	if _, err := testEngine.Head(context.Background(), r, "err500", prov(t, models.PackageGeneric)); err == nil {
+		t.Error("expected error for HEAD of 500 upstream")
+	}
+}
+
+func TestHeadCachedIndex(t *testing.T) {
+	requireStack(t)
+	ctx := context.Background()
+	r := seed(t, models.Remote{Name: "eng-headidx", PackageType: models.PackageNPM, RepoType: models.RepoTypeRemote, BaseURL: upstream.URL, CheckMutable: true, MutableTTL: 3600})
+	p := prov(t, models.PackageNPM)
+	// Cache the mutable index, then HEAD is answered from the stored index.
+	res, err := testEngine.Fetch(ctx, r, "pkg", p)
+	if err != nil {
+		t.Fatal(err)
+	}
+	res.Reader.Close()
+	h, err := testEngine.Head(ctx, r, "pkg", p)
+	if err != nil || h.Source != "cache" {
+		t.Errorf("head of cached index: %+v %v", h, err)
+	}
+}
+
 func TestUpstreamErrorUnwrap(t *testing.T) {
 	base := context.DeadlineExceeded
 	ue := &UpstreamError{Err: base}
diff --git a/internal/server/server_test.go b/internal/server/server_test.go
index 141539e..f744cfb 100644
--- a/internal/server/server_test.go
+++ b/internal/server/server_test.go
@@ -192,6 +192,7 @@ func TestServerLocalUpload(t *testing.T) {
 	defer req(t, "DELETE", "/api/v2/remotes/srv-local", "")
 
 	rq, _ := http.NewRequest("PUT", testTS.URL+"/api/v2/remotes/srv-local/files/dir/hello.bin", strings.NewReader("local payload"))
+	rq.Header.Set("Content-Type", "text/plain") // exercise the content-type branch
 	resp, err := http.DefaultClient.Do(rq)
 	if err != nil || resp.StatusCode != 201 {
 		t.Fatalf("upload: %v %d", err, resp.StatusCode)