fix: harden model catalog projections

tools/tht/internal/modelmigration/migration.go

@@ -119,9 +119,10 @@ func Run(request Request) error {
 	if !filepath.IsAbs(request.InstallationPath) || filepath.Base(request.InstallationPath) != "thothii-installation.yaml" {
 		return errors.New("installation migration requires an absolute thothii-installation.yaml path")
 	}
-	if !filepath.IsAbs(request.OutputPath) || filepath.Base(request.OutputPath) != "thothii-installation.yaml" ||
+	outputExtension := strings.ToLower(filepath.Ext(request.OutputPath))
+	if !filepath.IsAbs(request.OutputPath) || outputExtension != ".yaml" && outputExtension != ".yml" ||
 		filepath.Clean(request.OutputPath) == filepath.Clean(request.InstallationPath) {
-		return errors.New("installation migration output must be a different absolute thothii-installation.yaml path")
+		return errors.New("installation migration output must be a different absolute YAML path")
 	}
 	if request.SessionDefault == "" || request.EmbeddingID == "" || request.EmbeddingDimensions <= 0 {
 		return errors.New("installation migration requires session default, embedding id, and positive embedding dimensions")

tools/tht/internal/modelmigration/migration_test.go

@@ -69,6 +69,19 @@ func TestRunReportsProviderAuthenticationConflictAndPublishesNothing(t *testing.
 	}
 }
 
+func TestRunAcceptsVersionedYAMLCandidateFilename(t *testing.T) {
+	fixture := migrationFixture(t, false)
+	request := fixture.request()
+	request.OutputPath = filepath.Join(filepath.Dir(request.OutputPath), "thothii-installation.v2.yaml")
+
+	if err := Run(request); err != nil {
+		t.Fatalf("Run() error = %v", err)
+	}
+	if info, err := os.Stat(request.OutputPath); err != nil || !info.Mode().IsRegular() {
+		t.Fatalf("versioned candidate: info=%v err=%v", info, err)
+	}
+}
+
 type migrationTestFixture struct {
 	legacy string
 	output string