feat: Add API-based refresh mode for smoother updates

Add display.refresh_mode option:
- 'page' (default): Full page refresh via meta refresh
- 'api': Fetch /api/status and update DOM without reload

Also add display.refresh_interval (default: 30s, min: 5s)

API mode updates: status indicators, response times, uptimes,
errors, overall status banner, and page title counts.
History bars remain static until full page refresh.

1 files changed, 24 insertions, 0 deletions

diff --git a/internal/config/config.go b/internal/config/config.go
index 5f05b96..0c8b430 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -44,6 +44,12 @@ type DisplayConfig struct {
 	Timezone string `yaml:"timezone"`
 	// Scale adjusts the overall UI scale (default: 1.0, range: 0.5-2.0)
 	Scale float64 `yaml:"scale"`
+	// RefreshMode controls how the page updates:
+	//   "page" - Full page refresh via meta refresh (default)
+	//   "api"  - Fetch updates via API without page reload
+	RefreshMode string `yaml:"refresh_mode"`
+	// RefreshInterval is how often to refresh in seconds (default: 30)
+	RefreshInterval int `yaml:"refresh_interval"`
 }
 
 // SiteConfig contains site metadata
@@ -252,6 +258,12 @@ func (c *Config) applyDefaults() {
 	} else if c.Display.Scale > 2.0 {
 		c.Display.Scale = 2.0
 	}
+	if c.Display.RefreshMode == "" {
+		c.Display.RefreshMode = "page"
+	}
+	if c.Display.RefreshInterval == 0 {
+		c.Display.RefreshInterval = 30
+	}
 
 	// Apply API defaults
 	if c.API.Access == "" {
@@ -485,6 +497,18 @@ func (c *Config) validate() error {
 		return fmt.Errorf("api.access is 'authenticated' but no api.keys provided")
 	}
 
+	// Validate refresh mode
+	switch c.Display.RefreshMode {
+	case "page", "api":
+		// Valid modes
+	default:
+		return fmt.Errorf("invalid display.refresh_mode %q (must be page or api)", c.Display.RefreshMode)
+	}
+
+	if c.Display.RefreshInterval < 5 {
+		return fmt.Errorf("display.refresh_interval must be at least 5 seconds, got %d", c.Display.RefreshInterval)
+	}
+
 	return nil
 }