feat: support multiple destinations per source in link config

- Add LinkMap custom type with YAML unmarshaling for backward compatibility
- Support both old format (single string) and new format (array of strings)
- Update link manager to handle multiple destinations per source
- Update state tracking for multiple destinations
- Update all tests to use new LinkMap type
- Add documentation for multiple link destinations

Example usage:
  link:
    # Old format still works
    "source": "dest"
    # New format for multiple destinations
    "source": ["dest1", "dest2", "dest3"]

Author: pablopunk

README.md

@@ -177,6 +177,27 @@ config:
       apt: "apt install -y tool"
 ```
 
+### Multiple Link Destinations
+
+Link the same source file to multiple destinations (useful for monorepos or shared configs):
+
+```yaml
+config:
+  shared-configs:
+    os: ["mac"]
+    link:
+      # Old format still works (single destination)
+      "./config/shared/settings.json": "~/.config/settings.json"
+      
+      # New format for multiple destinations
+      "./config/shared/.eslintrc":
+        - "~/project-a/.eslintrc"
+        - "~/project-b/.eslintrc"
+        - "~/project-c/.eslintrc"
+```
+
+Both formats can be mixed in the same component. The old format (`source: dest`) is automatically converted to a single-item array for backward compatibility.
+
 ### Advanced Features
 
 #### Nested Configs

internal/component/component_test.go

@@ -34,19 +34,19 @@ func createTestComponentManager(t *testing.T, dryRun bool) (*Manager, string) {
 
 	rawConfig := map[string]config.Component{
 		"bash": {
-			Link: map[string]string{
-				"bash/.bashrc": filepath.Join(homeDir, ".bashrc"),
+			Link: config.LinkMap{
+				"bash/.bashrc": []string{filepath.Join(homeDir, ".bashrc")},
 			},
 		},
 		"git": {
-			Link: map[string]string{
-				"bash/.bashrc": filepath.Join(homeDir, ".gitconfig"),
+			Link: config.LinkMap{
+				"bash/.bashrc": []string{filepath.Join(homeDir, ".gitconfig")},
 			},
 			PostLink: "echo 'git post-link'",
 		},
 		"docker": {
-			Link: map[string]string{
-				"bash/.bashrc": filepath.Join(homeDir, ".dockerrc"),
+			Link: config.LinkMap{
+				"bash/.bashrc": []string{filepath.Join(homeDir, ".dockerrc")},
 			},
 			PostLink: "echo 'docker post-link'",
 		},
@@ -83,7 +83,7 @@ func createTestComponentManager(t *testing.T, dryRun bool) (*Manager, string) {
 func TestNewManager(t *testing.T) {
 	rawConfig := map[string]config.Component{
 		"test": {
-			Link: map[string]string{"test": "~/.test"},
+			Link: config.LinkMap{"test": []string{"~/.test"}},
 		},
 	}
 

internal/config/config.go

@@ -17,10 +17,60 @@ type Config struct {
 
 type ComponentMap map[string]Component
 
+// LinkMap is a custom type that supports both single string and array of strings as values
+// This allows backward compatibility with the old format while supporting multiple destinations per source
+type LinkMap map[string][]string
+
+// UnmarshalYAML implements custom YAML unmarshaling for LinkMap
+// Supports both formats:
+//
+//	Old (single): "source": "dest"
+//	New (multiple): "source": ["dest1", "dest2"]
+func (lm *LinkMap) UnmarshalYAML(node *yaml.Node) error {
+	if node.Kind != yaml.MappingNode {
+		return fmt.Errorf("link must be a mapping, got %s", node.Tag)
+	}
+
+	*lm = make(LinkMap)
+
+	for i := 0; i < len(node.Content); i += 2 {
+		keyNode := node.Content[i]
+		valueNode := node.Content[i+1]
+
+		var key string
+		if err := keyNode.Decode(&key); err != nil {
+			return fmt.Errorf("failed to decode link key: %w", err)
+		}
+
+		var destinations []string
+
+		switch valueNode.Kind {
+		case yaml.ScalarNode:
+			// Old format: single string value
+			var dest string
+			if err := valueNode.Decode(&dest); err != nil {
+				return fmt.Errorf("failed to decode link destination for %s: %w", key, err)
+			}
+			destinations = []string{dest}
+		case yaml.SequenceNode:
+			// New format: array of destinations
+			if err := valueNode.Decode(&destinations); err != nil {
+				return fmt.Errorf("failed to decode link destinations for %s: %w", key, err)
+			}
+		default:
+			return fmt.Errorf("link value for %s must be a string or array, got %s", key, valueNode.Tag)
+		}
+
+		(*lm)[key] = destinations
+	}
+
+	return nil
+}
+
 type Component struct {
 	Install     map[string]string `yaml:"install,omitempty"`
 	Uninstall   map[string]string `yaml:"uninstall,omitempty"`
-	Link        map[string]string `yaml:"link,omitempty"`
+	Link        LinkMap           `yaml:"link,omitempty"`
 	PostInstall string            `yaml:"postinstall,omitempty"`
 	PostLink    string            `yaml:"postlink,omitempty"`
 	OS          []string          `yaml:"os,omitempty"`

internal/link/link.go

@@ -5,6 +5,8 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
+
+	"github.com/pablopunk/dot/internal/config"
 )
 
 type Manager struct {
@@ -28,23 +30,27 @@ type LinkResult struct {
 	Error  error
 }
 
-func (m *Manager) CreateLinks(linkMap map[string]string) ([]LinkResult, error) {
+func (m *Manager) CreateLinks(linkMap config.LinkMap) ([]LinkResult, error) {
 	var results []LinkResult
 
-	for source, target := range linkMap {
-		result := m.createLink(source, target)
-		results = append(results, result)
+	for source, targets := range linkMap {
+		for _, target := range targets {
+			result := m.createLink(source, target)
+			results = append(results, result)
+		}
 	}
 
 	return results, nil
 }
 
 // NeedsLinking checks if any of the links in linkMap need to be created or updated
 // Returns true if at least one link needs work, false if all links already exist correctly
-func (m *Manager) NeedsLinking(linkMap map[string]string) bool {
-	for source, target := range linkMap {
-		if m.needsLinking(source, target) {
-			return true
+func (m *Manager) NeedsLinking(linkMap config.LinkMap) bool {
+	for source, targets := range linkMap {
+		for _, target := range targets {
+			if m.needsLinking(source, target) {
+				return true
+			}
 		}
 	}
 	return false
@@ -187,12 +193,14 @@ func (m *Manager) createLink(source, target string) LinkResult {
 	}
 }
 
-func (m *Manager) RemoveLinks(linkMap map[string]string) ([]LinkResult, error) {
+func (m *Manager) RemoveLinks(linkMap config.LinkMap) ([]LinkResult, error) {
 	var results []LinkResult
 
-	for source, target := range linkMap {
-		result := m.removeLink(source, target)
-		results = append(results, result)
+	for source, targets := range linkMap {
+		for _, target := range targets {
+			result := m.removeLink(source, target)
+			results = append(results, result)
+		}
 	}
 
 	return results, nil

internal/link/link_test.go

@@ -4,6 +4,8 @@ import (
 	"os"
 	"path/filepath"
 	"testing"
+
+	"github.com/pablopunk/dot/internal/config"
 )
 
 func TestNewManager(t *testing.T) {
@@ -46,8 +48,8 @@ func TestCreateLinks(t *testing.T) {
 
 	manager := NewManager(baseDir, false, false)
 
-	linkMap := map[string]string{
-		"bash/.bashrc": filepath.Join(homeDir, ".bashrc"),
+	linkMap := config.LinkMap{
+		"bash/.bashrc": []string{filepath.Join(homeDir, ".bashrc")},
 	}
 
 	results, err := manager.CreateLinks(linkMap)
@@ -118,8 +120,8 @@ func TestCreateLinksExistingCorrectLink(t *testing.T) {
 
 	manager := NewManager(baseDir, false, false)
 
-	linkMap := map[string]string{
-		"bash/.bashrc": targetFile,
+	linkMap := config.LinkMap{
+		"bash/.bashrc": []string{targetFile},
 	}
 
 	results, err := manager.CreateLinks(linkMap)
@@ -159,8 +161,8 @@ func TestCreateLinksDryRun(t *testing.T) {
 
 	manager := NewManager(baseDir, true, false) // dry run enabled
 
-	linkMap := map[string]string{
-		"bash/.bashrc": filepath.Join(homeDir, ".bashrc"),
+	linkMap := config.LinkMap{
+		"bash/.bashrc": []string{filepath.Join(homeDir, ".bashrc")},
 	}
 
 	results, err := manager.CreateLinks(linkMap)
@@ -211,8 +213,8 @@ func TestRemoveLinks(t *testing.T) {
 
 	manager := NewManager(baseDir, false, false)
 
-	linkMap := map[string]string{
-		"bash/.bashrc": targetFile,
+	linkMap := config.LinkMap{
+		"bash/.bashrc": []string{targetFile},
 	}
 
 	results, err := manager.RemoveLinks(linkMap)

internal/profile/profile_test.go

@@ -9,8 +9,8 @@ import (
 func createTestConfig() *config.Config {
 	rawConfig := map[string]config.Component{
 		"bash": {
-			Link: map[string]string{
-				"bash/.bashrc": "~/.bashrc",
+			Link: config.LinkMap{
+				"bash/.bashrc": []string{"~/.bashrc"},
 			},
 		},
 		"git": {
@@ -145,9 +145,9 @@ func TestGetActiveComponents(t *testing.T) {
 
 func TestGetActiveComponents_MultipleProfiles(t *testing.T) {
 	rawConfig := map[string]config.Component{
-		"common": {Link: map[string]string{"s": "t"}},
-		"c1":     {Link: map[string]string{"s": "t"}},
-		"c2":     {Link: map[string]string{"s": "t"}},
+		"common": {Link: config.LinkMap{"s": []string{"t"}}},
+		"c1":     {Link: config.LinkMap{"s": []string{"t"}}},
+		"c2":     {Link: config.LinkMap{"s": []string{"t"}}},
 	}
 
 	configMap := make(map[string]interface{})

internal/state/state.go

@@ -8,6 +8,7 @@ import (
 
 	"gopkg.in/yaml.v3"
 
+	"github.com/pablopunk/dot/internal/config"
 	"github.com/pablopunk/dot/internal/profile"
 )
 
@@ -25,7 +26,7 @@ type ComponentState struct {
 	PackageManager    string            `yaml:"package_manager,omitempty"`
 	InstallCommand    string            `yaml:"install_command,omitempty"`
 	UninstallCommands map[string]string `yaml:"uninstall_commands,omitempty"` // Store uninstall commands for when component is removed
-	Links             map[string]string `yaml:"links,omitempty"`
+	Links             config.LinkMap    `yaml:"links,omitempty"`
 	PostInstallRan    bool              `yaml:"post_install_ran"`
 	PostLinkRan       bool              `yaml:"post_link_ran"`
 	ContentHash       string            `yaml:"content_hash,omitempty"` // Hash of component content for rename detection
@@ -117,7 +118,7 @@ func (m *Manager) IsComponentInstalled(componentInfo profile.ComponentInfo) bool
 	return exists
 }
 
-func (m *Manager) MarkComponentInstalled(componentInfo profile.ComponentInfo, packageManager, installCommand string, links map[string]string) {
+func (m *Manager) MarkComponentInstalled(componentInfo profile.ComponentInfo, packageManager, installCommand string, links config.LinkMap) {
 	key := componentInfo.FullName()
 	m.lockFile.InstalledComponents[key] = ComponentState{
 		ProfileName:       componentInfo.ProfileName,
@@ -207,7 +208,7 @@ func (m *Manager) GetComponentState(componentInfo profile.ComponentInfo) (Compon
 	return state, exists
 }
 
-func (m *Manager) HasChangedSince(componentInfo profile.ComponentInfo, links map[string]string) bool {
+func (m *Manager) HasChangedSince(componentInfo profile.ComponentInfo, links config.LinkMap) bool {
 	state, exists := m.GetComponentState(componentInfo)
 	if !exists {
 		return true // Not installed, so it's a change
@@ -218,10 +219,20 @@ func (m *Manager) HasChangedSince(componentInfo profile.ComponentInfo, links map
 		return true
 	}
 
-	for source, target := range links {
-		if stateTarget, exists := state.Links[source]; !exists || stateTarget != target {
+	for source, targets := range links {
+		stateTargets, exists := state.Links[source]
+		if !exists {
 			return true
 		}
+		if len(stateTargets) != len(targets) {
+			return true
+		}
+		// Check each target matches
+		for i, target := range targets {
+			if stateTargets[i] != target {
+				return true
+			}
+		}
 	}
 
 	return false
@@ -285,7 +296,7 @@ func (m *Manager) migrateRenamedComponent(oldKey string, newComponent profile.Co
 		PackageManager:    oldState.PackageManager,
 		InstallCommand:    oldState.InstallCommand,
 		UninstallCommands: newComponent.Component.Uninstall, // Update uninstall commands to new component's
-		Links:             map[string]string{},              // Reset links so they get re-created
+		Links:             config.LinkMap{},                 // Reset links so they get re-created
 		PostInstallRan:    oldState.PostInstallRan,
 		PostLinkRan:       false, // Reset post-link state since links will be re-created
 		ContentHash:       newComponent.Component.ContentHash(),

internal/state/state_test.go

@@ -6,6 +6,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/pablopunk/dot/internal/config"
 	"github.com/pablopunk/dot/internal/profile"
 )
 
@@ -92,7 +93,7 @@ func TestComponentTracking(t *testing.T) {
 	}
 
 	// Mark as installed
-	links := map[string]string{"git/.gitconfig": "~/.gitconfig"}
+	links := config.LinkMap{"git/.gitconfig": []string{"~/.gitconfig"}}
 	manager.MarkComponentInstalled(component, "brew", "brew install git", links)
 
 	// Should now be installed
@@ -193,7 +194,7 @@ func TestHasChangedSince(t *testing.T) {
 	}
 
 	// Not installed - should be changed
-	links := map[string]string{"git/.gitconfig": "~/.gitconfig"}
+	links := config.LinkMap{"git/.gitconfig": []string{"~/.gitconfig"}}
 	if !manager.HasChangedSince(component, links) {
 		t.Error("HasChangedSince should return true for uninstalled component")
 	}
@@ -204,10 +205,9 @@ func TestHasChangedSince(t *testing.T) {
 		t.Error("HasChangedSince should return false for unchanged component")
 	}
 
-	// Change links
-	newLinks := map[string]string{
-		"git/.gitconfig": "~/.gitconfig",
-		"git/.gitignore": "~/.gitignore",
+	// Change links - add another destination to same source
+	newLinks := config.LinkMap{
+		"git/.gitconfig": []string{"~/.gitconfig", "~/.config/git/config"},
 	}
 	if !manager.HasChangedSince(component, newLinks) {
 		t.Error("HasChangedSince should return true for changed links")