fix: validate Fabric chat URL host and tidy Ollama responses

## CHANGES
- Set NDJSON content type before checking upstream errors
- Reject parsed URLs that omit a hostname
- Remove hardcoded eval count placeholders from responses
- Add unit tests for Fabric chat URL builder
- Cover colon-port, host:port, and IP address inputs

internal/server/ollama.go

@@ -217,6 +217,10 @@ func (f APIConvert) ollamaChat(c *gin.Context) {
 	}
 	defer fabricRes.Body.Close()
 
+	if prompt.Stream {
+		c.Header("Content-Type", "application/x-ndjson")
+	}
+
 	if fabricRes.StatusCode < http.StatusOK || fabricRes.StatusCode >= http.StatusMultipleChoices {
 		bodyBytes, readErr := io.ReadAll(fabricRes.Body)
 		if readErr != nil {
@@ -234,10 +238,6 @@ func (f APIConvert) ollamaChat(c *gin.Context) {
 		return
 	}
 
-	if prompt.Stream {
-		c.Header("Content-Type", "application/x-ndjson")
-	}
-
 	var contentBuilder strings.Builder
 	scanner := bufio.NewScanner(fabricRes.Body)
 	scanner.Buffer(make([]byte, 0, 64*1024), 1024*1024)
@@ -304,9 +304,7 @@ func (f APIConvert) ollamaChat(c *gin.Context) {
 			Done:               true,
 			TotalDuration:      time.Since(now).Nanoseconds(),
 			LoadDuration:       int(time.Since(now).Nanoseconds()),
-			PromptEvalCount:    42,
 			PromptEvalDuration: int(time.Since(now).Nanoseconds()),
-			EvalCount:          420,
 			EvalDuration:       time.Since(now).Nanoseconds(),
 		}
 		c.JSON(200, response)
@@ -327,9 +325,7 @@ func (f APIConvert) ollamaChat(c *gin.Context) {
 		Done:               true,
 		TotalDuration:      time.Since(now).Nanoseconds(),
 		LoadDuration:       int(time.Since(now).Nanoseconds()),
-		PromptEvalCount:    42,
 		PromptEvalDuration: int(time.Since(now).Nanoseconds()),
-		EvalCount:          420,
 		EvalDuration:       time.Since(now).Nanoseconds(),
 	}
 	if err := writeOllamaResponseStruct(c, finalResponse); err != nil {
@@ -346,6 +342,9 @@ func buildFabricChatURL(addr string) (string, error) {
 		if err != nil {
 			return "", fmt.Errorf("invalid address: %w", err)
 		}
+		if parsed.Host == "" {
+			return "", fmt.Errorf("invalid address: missing host")
+		}
 		return strings.TrimRight(parsed.String(), "/"), nil
 	}
 	if strings.HasPrefix(addr, ":") {

internal/server/ollama_test.go

@@ -0,0 +1,88 @@
+package restapi
+
+import (
+	"testing"
+)
+
+func TestBuildFabricChatURL(t *testing.T) {
+	tests := []struct {
+		name    string
+		addr    string
+		want    string
+		wantErr bool
+	}{
+		{
+			name:    "empty address",
+			addr:    "",
+			want:    "",
+			wantErr: true,
+		},
+		{
+			name:    "valid http URL",
+			addr:    "http://localhost:8080",
+			want:    "http://localhost:8080",
+			wantErr: false,
+		},
+		{
+			name:    "valid https URL",
+			addr:    "https://api.example.com",
+			want:    "https://api.example.com",
+			wantErr: false,
+		},
+		{
+			name:    "http URL with trailing slash",
+			addr:    "http://localhost:8080/",
+			want:    "http://localhost:8080",
+			wantErr: false,
+		},
+		{
+			name:    "malformed URL - missing host",
+			addr:    "http://",
+			want:    "",
+			wantErr: true,
+		},
+		{
+			name:    "malformed URL - port only with http",
+			addr:    "https://:8080",
+			want:    "https://:8080",
+			wantErr: false,
+		},
+		{
+			name:    "colon-prefixed port",
+			addr:    ":8080",
+			want:    "http://127.0.0.1:8080",
+			wantErr: false,
+		},
+		{
+			name:    "bare host:port",
+			addr:    "localhost:8080",
+			want:    "http://localhost:8080",
+			wantErr: false,
+		},
+		{
+			name:    "bare hostname",
+			addr:    "localhost",
+			want:    "http://localhost",
+			wantErr: false,
+		},
+		{
+			name:    "IP address with port",
+			addr:    "192.168.1.1:3000",
+			want:    "http://192.168.1.1:3000",
+			wantErr: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := buildFabricChatURL(tt.addr)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("buildFabricChatURL() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if got != tt.want {
+				t.Errorf("buildFabricChatURL() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}