Feature Flags

Feature flags gate experimental functionality behind user-configurable settings, enabling safe rollout (default off), user opt-in, and easy rollback.

Checking Feature State

go
import "github.com/marcus/sidecar/internal/features"

if features.IsEnabled("tmux_interactive_input") {
    // Feature-gated code
}

Adding a New Feature Flag

1. Define the feature in internal/features/features.go:

go
var MyNewFeature = Feature{
    Name:        "my_new_feature",
    Default:     false,
    Description: "Description of what this enables",
}

1. Add to the allFeatures slice:

go
var allFeatures = []Feature{
    TmuxInteractiveInput,
    MyNewFeature, // Add here
}

1. Use the feature check in your code:

go
if features.IsEnabled("my_new_feature") {
    // New functionality
}

User Configuration

Config file (~/.config/sidecar/config.json)

json
{
  "features": {
    "flags": {
      "tmux_interactive_input": true
    }
  }
}

CLI override (takes precedence over config)

bash
sidecar --enable-feature=tmux_interactive_input
sidecar --disable-feature=tmux_interactive_input
sidecar --enable-feature=feature1,feature2   # Multiple features

Unknown feature names in CLI flags produce a warning but do not prevent startup.

Priority Order

Feature state resolves in this order (first match wins):

1. CLI override (--enable-feature, --disable-feature)
2. Config file (features.flags in config.json)
3. Default value (defined in code)

Available Features

| Feature | Default | Description | |---------|---------|-------------| | tmux_interactive_input | true | Write support for tmux panes | | tmux_inline_edit | true | Inline file editing via tmux in files plugin | | notes_plugin | false | Notes plugin for capturing quick notes |

API Reference

go
features.IsEnabled(name string) bool           // Check if enabled
features.List() map[string]bool                 // All features with current state
features.ListAll() []Feature                    // All features with metadata
features.SetEnabled(name string, enabled bool) error  // Persist to config
features.SetOverride(name string, enabled bool) // Runtime override (not persisted)
features.IsKnownFeature(name string) bool       // Check if registered

Best Practices

• Use snake_case for feature names (e.g., my_new_feature)
• New experimental features should default to false
• Provide clear descriptions for each feature
• Document features in docs/guides/deprecated/feature-flags.md when adding them
• Remove feature flags once features are stable