feat: add appearance show-scroll-bars setting

docs/spec.md

@@ -317,7 +317,7 @@ dock:
 - **Single binary**: No runtime dependencies. Distributed as a compiled Go binary.
 - **Fast**: `plan` should complete in under 2 seconds for a full spec.
 - **Safe**: `plan` is always read-only. `apply` prompts before writing unless `--auto-approve`.
-- **macOS compatibility**: Target macOS 15 (Tahoe) to start. Compatibility with multiple versions is a future goal.
+- **macOS compatibility**: Target macOS 26 (Tahoe) to start. Compatibility with multiple versions is a future goal.
 - **Extensible**: Adding a new provider requires only: (a) implement the `Provider` interface, (b) add entries to the registry with the new provider name.
 
 ## Success Criteria

examples/macform.yaml

@@ -4,6 +4,13 @@
 # valid values, and macOS system default. Copy this file to your project root
 # (or home directory) as macform.yaml and customise to taste.
 
+appearance:
+  # Description: When to show scroll bars
+  # Type: string
+  # Valid values: automatic | when-scrolling | always
+  # Default: automatic
+  show-scroll-bars: automatic
+
 dock:
   # Description: Auto-hide the Dock when the pointer is not near it
   # Type: bool

internal/registry/appearance.go

@@ -0,0 +1,14 @@
+package registry
+
+import "github.com/vsimon/macform/internal/provider"
+
+var appearanceSettings = []SettingDef{
+	{
+		SpecKey:  "show-scroll-bars",
+		Type:     "string",
+		Provider: provider.NewDefaults("NSGlobalDomain", "AppleShowScrollBars", "string"),
+		ValueMap: map[string]string{
+			"automatic": "Automatic", "when-scrolling": "WhenScrolling", "always": "Always",
+		},
+	},
+}

internal/registry/registry.go

@@ -116,6 +116,7 @@ var sections = map[string][]SettingDef{
 			Provider: provider.NewOsascript("slightly-dim-on-battery", slightlyDimReadScript, slightlyDimWriteScript, "true"),
 		},
 	},
+	"appearance":     appearanceSettings,
 	"control-center": controlCenterSettings,
 	"trackpad":       trackpadSettings,
 	"keyboard":       keyboardSettings,
@@ -205,7 +206,7 @@ func SectionKeys(section string) []SettingDef {
 
 // Sections returns the ordered list of section names.
 func Sections() []string {
-	return []string{"dock", "finder", "display", "battery", "control-center", "trackpad", "keyboard", "hot-corners"}
+	return []string{"appearance", "dock", "finder", "display", "battery", "control-center", "trackpad", "keyboard", "hot-corners"}
 }
 
 // Encode converts a spec value to its system (defaults) representation.