Add nudge_channels to MessagingConfig schema (gt-3shmx)

- Add NudgeChannels field to MessagingConfig struct in types.go
- Initialize NudgeChannels map in NewMessagingConfig()
- Add validation in validateMessagingConfig(): channel names must be
  non-empty and each channel must have at least one recipient
- Add tests for valid nudge channels and empty recipient validation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/config/loader.go

@@ -629,6 +629,9 @@ func validateMessagingConfig(c *MessagingConfig) error {
 	if c.Announces == nil {
 		c.Announces = make(map[string]AnnounceConfig)
 	}
+	if c.NudgeChannels == nil {
+		c.NudgeChannels = make(map[string][]string)
+	}
 
 	// Validate lists have at least one recipient
 	for name, recipients := range c.Lists {
@@ -657,6 +660,16 @@ func validateMessagingConfig(c *MessagingConfig) error {
 		}
 	}
 
+	// Validate nudge channels have non-empty names and at least one recipient
+	for name, recipients := range c.NudgeChannels {
+		if name == "" {
+			return fmt.Errorf("%w: nudge channel name cannot be empty", ErrMissingField)
+		}
+		if len(recipients) == 0 {
+			return fmt.Errorf("%w: nudge channel '%s' has no recipients", ErrMissingField, name)
+		}
+	}
+
 	return nil
 }
 

internal/config/loader_test.go

@@ -566,6 +566,8 @@ func TestMessagingConfigRoundTrip(t *testing.T) {
 		Readers:     []string{"@town"},
 		RetainCount: 100,
 	}
+	original.NudgeChannels["workers"] = []string{"gastown/polecats/*", "gastown/crew/*"}
+	original.NudgeChannels["witnesses"] = []string{"*/witness"}
 
 	if err := SaveMessagingConfig(path, original); err != nil {
 		t.Fatalf("SaveMessagingConfig: %v", err)
@@ -606,6 +608,17 @@ func TestMessagingConfigRoundTrip(t *testing.T) {
 	if a, ok := loaded.Announces["alerts"]; !ok || a.RetainCount != 100 {
 		t.Error("announce not preserved")
 	}
+
+	// Check nudge channels
+	if len(loaded.NudgeChannels) != 2 {
+		t.Errorf("NudgeChannels count = %d, want 2", len(loaded.NudgeChannels))
+	}
+	if workers, ok := loaded.NudgeChannels["workers"]; !ok || len(workers) != 2 {
+		t.Error("workers nudge channel not preserved")
+	}
+	if witnesses, ok := loaded.NudgeChannels["witnesses"]; !ok || len(witnesses) != 1 {
+		t.Error("witnesses nudge channel not preserved")
+	}
 }
 
 func TestMessagingConfigValidation(t *testing.T) {
@@ -696,6 +709,27 @@ func TestMessagingConfigValidation(t *testing.T) {
 			},
 			wantErr: true,
 		},
+		{
+			name: "valid config with nudge channels",
+			config: &MessagingConfig{
+				Type:    "messaging",
+				Version: 1,
+				NudgeChannels: map[string][]string{
+					"workers": {"gastown/polecats/*", "gastown/crew/*"},
+				},
+			},
+			wantErr: false,
+		},
+		{
+			name: "nudge channel with no recipients",
+			config: &MessagingConfig{
+				Version: 1,
+				NudgeChannels: map[string][]string{
+					"empty": {},
+				},
+			},
+			wantErr: true,
+		},
 	}
 
 	for _, tt := range tests {

internal/config/types.go

@@ -278,6 +278,11 @@ type MessagingConfig struct {
 	// Used for broadcast announcements that don't need acknowledgment.
 	// Example: {"alerts": {"readers": ["@town"]}}
 	Announces map[string]AnnounceConfig `json:"announces,omitempty"`
+
+	// NudgeChannels are named groups for real-time nudge fan-out.
+	// Like mailing lists but for tmux send-keys instead of durable mail.
+	// Example: {"workers": ["gastown/polecats/*", "gastown/crew/*"], "witnesses": ["*/witness"]}
+	NudgeChannels map[string][]string `json:"nudge_channels,omitempty"`
 }
 
 // QueueConfig represents a work queue configuration.
@@ -311,5 +316,6 @@ func NewMessagingConfig() *MessagingConfig {
 		Lists:         make(map[string][]string),
 		Queues:        make(map[string]QueueConfig),
 		Announces:     make(map[string]AnnounceConfig),
+		NudgeChannels: make(map[string][]string),
 	}
 }