feat(mail): add deacon/ identity support

Add deacon/ as a town-level mail identity alongside mayor/.
Both addressToIdentity() and identityToAddress() now handle
deacon/deacon/ consistently with trailing slash preservation.

Tested with bd mail send deacon/ and bd mail inbox --identity deacon/

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

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

internal/mail/types.go

@@ -217,16 +217,21 @@ func ParseMessageType(s string) MessageType {
 // Examples:
 //   - "mayor/" → "mayor/"
 //   - "mayor" → "mayor/"
+//   - "deacon/" → "deacon/"
+//   - "deacon" → "deacon/"
 //   - "gastown/Toast" → "gastown-Toast"
 //   - "gastown/refinery" → "gastown-refinery"
 //   - "gastown/" → "gastown" (rig broadcast)
 func addressToIdentity(address string) string {
-	// Mayor special case - always use "mayor/" for consistency
+	// Town-level agents: mayor and deacon keep trailing slash
 	if address == "mayor" || address == "mayor/" {
 		return "mayor/"
 	}
+	if address == "deacon" || address == "deacon/" {
+		return "deacon/"
+	}
 
-	// Trim trailing slash for non-mayor addresses
+	// Trim trailing slash for rig-level addresses
 	if len(address) > 0 && address[len(address)-1] == '/' {
 		address = address[:len(address)-1]
 	}
@@ -248,12 +253,19 @@ func addressToIdentity(address string) string {
 //
 // Examples:
 //   - "mayor" → "mayor/"
+//   - "mayor/" → "mayor/"
+//   - "deacon" → "deacon/"
+//   - "deacon/" → "deacon/"
 //   - "gastown-Toast" → "gastown/Toast"
 //   - "gastown-refinery" → "gastown/refinery"
 func identityToAddress(identity string) string {
-	if identity == "mayor" {
+	// Town-level agents
+	if identity == "mayor" || identity == "mayor/" {
 		return "mayor/"
 	}
+	if identity == "deacon" || identity == "deacon/" {
+		return "deacon/"
+	}
 
 	// Find first dash and replace with /
 	// gastown-Toast → gastown/Toast

internal/mail/types_test.go

@@ -0,0 +1,63 @@
+package mail
+
+import "testing"
+
+func TestAddressToIdentity(t *testing.T) {
+	tests := []struct {
+		address  string
+		expected string
+	}{
+		// Town-level agents keep trailing slash
+		{"mayor", "mayor/"},
+		{"mayor/", "mayor/"},
+		{"deacon", "deacon/"},
+		{"deacon/", "deacon/"},
+
+		// Rig-level agents use dash separator
+		{"gastown/Toast", "gastown-Toast"},
+		{"gastown/refinery", "gastown-refinery"},
+		{"gastown/witness", "gastown-witness"},
+
+		// Rig broadcast (trailing slash removed)
+		{"gastown/", "gastown"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.address, func(t *testing.T) {
+			got := addressToIdentity(tt.address)
+			if got != tt.expected {
+				t.Errorf("addressToIdentity(%q) = %q, want %q", tt.address, got, tt.expected)
+			}
+		})
+	}
+}
+
+func TestIdentityToAddress(t *testing.T) {
+	tests := []struct {
+		identity string
+		expected string
+	}{
+		// Town-level agents
+		{"mayor", "mayor/"},
+		{"mayor/", "mayor/"},
+		{"deacon", "deacon/"},
+		{"deacon/", "deacon/"},
+
+		// Rig-level agents
+		{"gastown-Toast", "gastown/Toast"},
+		{"gastown-refinery", "gastown/refinery"},
+		{"gastown-witness", "gastown/witness"},
+
+		// Rig name only (adds trailing slash)
+		{"gastown", "gastown/"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.identity, func(t *testing.T) {
+			got := identityToAddress(tt.identity)
+			if got != tt.expected {
+				t.Errorf("identityToAddress(%q) = %q, want %q", tt.identity, got, tt.expected)
+			}
+		})
+	}
+}