create: inherit FROM model's renderer/parser

On main, the `RENDERER` and `PARSER` fields from the `Modelfile` don't
get propagated to a new model created with a `req.From` parameter. This
is easily triggered via `ollama run qwen3-coder`, then running some save
command like `/save qwen3-coder-custom`.

Added a regression test for this, and then open the config for the
"from" model in order to use its renderer/parser as a default for the
new model. This will fix the CLI and also API-based creates.

Fixes: https://github.com/ollama/ollama/issues/12792

server/create.go

@@ -119,6 +119,27 @@ func (s *Server) CreateHandler(c *gin.Context) {
 				if err != nil {
 					ch <- gin.H{"error": err.Error()}
 				}
+
+				if err == nil && !remote && (config.Renderer == "" || config.Parser == "") {
+					manifest, mErr := ParseNamedManifest(fromName)
+					if mErr == nil && manifest.Config.Digest != "" {
+						configPath, pErr := GetBlobsPath(manifest.Config.Digest)
+						if pErr == nil {
+							if cfgFile, fErr := os.Open(configPath); fErr == nil {
+								var baseConfig ConfigV2
+								if decErr := json.NewDecoder(cfgFile).Decode(&baseConfig); decErr == nil {
+									if config.Renderer == "" {
+										config.Renderer = baseConfig.Renderer
+									}
+									if config.Parser == "" {
+										config.Parser = baseConfig.Parser
+									}
+								}
+								cfgFile.Close()
+							}
+						}
+					}
+				}
 			}
 		} else if r.Files != nil {
 			baseLayers, err = convertModelFromFiles(r.Files, baseLayers, false, fn)

server/routes_create_test.go

@@ -188,6 +188,72 @@ func TestCreateFromModel(t *testing.T) {
 	})
 }
 
+func TestCreateFromModelInheritsRendererParser(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+
+	p := t.TempDir()
+	t.Setenv("OLLAMA_MODELS", p)
+	var s Server
+
+	const (
+		renderer = "custom-renderer"
+		parser   = "custom-parser"
+	)
+
+	_, digest := createBinFile(t, nil, nil)
+
+	w := createRequest(t, s.CreateHandler, api.CreateRequest{
+		Name:     "base",
+		Files:    map[string]string{"base.gguf": digest},
+		Renderer: renderer,
+		Parser:   parser,
+		Stream:   &stream,
+	})
+	if w.Code != http.StatusOK {
+		t.Fatalf("expected status code 200, actual %d", w.Code)
+	}
+
+	w = createRequest(t, s.CreateHandler, api.CreateRequest{
+		Name:   "child",
+		From:   "base",
+		Stream: &stream,
+	})
+	if w.Code != http.StatusOK {
+		t.Fatalf("expected status code 200, actual %d", w.Code)
+	}
+
+	manifest, err := ParseNamedManifest(model.ParseName("child"))
+	if err != nil {
+		t.Fatalf("parse manifest: %v", err)
+	}
+	if manifest.Config.Digest == "" {
+		t.Fatalf("unexpected empty config digest for child manifest")
+	}
+
+	configPath, err := GetBlobsPath(manifest.Config.Digest)
+	if err != nil {
+		t.Fatalf("config blob path: %v", err)
+	}
+
+	cfgFile, err := os.Open(configPath)
+	if err != nil {
+		t.Fatalf("open config blob: %v", err)
+	}
+	defer cfgFile.Close()
+
+	var cfg ConfigV2
+	if err := json.NewDecoder(cfgFile).Decode(&cfg); err != nil {
+		t.Fatalf("decode config: %v", err)
+	}
+
+	if cfg.Renderer != renderer {
+		t.Fatalf("expected renderer %q, got %q", renderer, cfg.Renderer)
+	}
+	if cfg.Parser != parser {
+		t.Fatalf("expected parser %q, got %q", parser, cfg.Parser)
+	}
+}
+
 func TestCreateRemovesLayers(t *testing.T) {
 	gin.SetMode(gin.TestMode)