fix: restore Gas Town types (agent, role, rig, convoy, slot) (GH#941)

v0.46.0 removed these types breaking gt install/doctor/sling/convoy commands.
This restores them as built-in types so `bd create --type=agent` works again.

Fixes GH#941

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

internal/types/types.go

@@ -442,9 +442,6 @@ func (s Status) IsValidWithCustom(customStatuses []string) bool {
 type IssueType string
 
 // Issue type constants
-// Note: Gas Town-specific types (agent, role, rig, convoy, slot) have been removed.
-// Use custom types via `bd config set types.custom "agent,role,..."` if needed.
-// These types are now identified by labels (gt:agent, gt:role, etc.) instead.
 const (
 	TypeBug          IssueType = "bug"
 	TypeFeature      IssueType = "feature"
@@ -455,13 +452,18 @@ const (
 	TypeMergeRequest IssueType = "merge-request" // Merge queue entry for refinery processing
 	TypeMolecule     IssueType = "molecule"      // Template molecule for issue hierarchies
 	TypeGate         IssueType = "gate"          // Async coordination gate
+	TypeAgent        IssueType = "agent"         // Agent identity bead
+	TypeRole         IssueType = "role"          // Agent role definition
+	TypeRig          IssueType = "rig"           // Rig identity bead (project container)
+	TypeConvoy       IssueType = "convoy"        // Cross-project tracking with reactive completion
 	TypeEvent        IssueType = "event"         // Operational state change record
+	TypeSlot         IssueType = "slot"          // Exclusive access slot (merge-slot gate)
 )
 
 // IsValid checks if the issue type value is valid (built-in types only)
 func (t IssueType) IsValid() bool {
 	switch t {
-	case TypeBug, TypeFeature, TypeTask, TypeEpic, TypeChore, TypeMessage, TypeMergeRequest, TypeMolecule, TypeGate, TypeEvent:
+	case TypeBug, TypeFeature, TypeTask, TypeEpic, TypeChore, TypeMessage, TypeMergeRequest, TypeMolecule, TypeGate, TypeAgent, TypeRole, TypeRig, TypeConvoy, TypeEvent, TypeSlot:
 		return true
 	}
 	return false

internal/types/types_test.go

@@ -442,14 +442,14 @@ func TestValidateForImport(t *testing.T) {
 			wantErr: false, // Should pass - federation trust model
 		},
 		{
-			name: "custom type agent is trusted",
+			name: "built-in type agent passes",
 			issue: Issue{
 				Title:     "Test Issue",
 				Status:    StatusOpen,
 				Priority:  1,
-				IssueType: IssueType("agent"), // Gas Town custom type
+				IssueType: TypeAgent, // Gas Town built-in type
 			},
-			wantErr: false, // Should pass - federation trust model
+			wantErr: false,
 		},
 		{
 			name: "empty type defaults to task (handled by SetDefaults)",
@@ -548,11 +548,12 @@ func TestIssueTypeIsValid(t *testing.T) {
 		{TypeMergeRequest, true},
 		{TypeMolecule, true},
 		{TypeGate, true},
+		{TypeAgent, true},
+		{TypeRole, true},
+		{TypeRig, true},
+		{TypeConvoy, true},
 		{TypeEvent, true},
-		// Gas Town types (agent, role, rig, convoy, slot) have been removed
-		// They are now identified by labels (gt:agent, etc.) instead
-		{IssueType("agent"), false},  // Now requires custom type config
-		{IssueType("convoy"), false}, // Now requires custom type config
+		{TypeSlot, true},
 		{IssueType("invalid"), false},
 		{IssueType(""), false},
 	}
@@ -585,13 +586,16 @@ func TestIssueTypeIsBuiltIn(t *testing.T) {
 		{TypeMergeRequest, true},
 		{TypeMolecule, true},
 		{TypeGate, true},
+		{TypeAgent, true},
+		{TypeRole, true},
+		{TypeRig, true},
+		{TypeConvoy, true},
 		{TypeEvent, true},
+		{TypeSlot, true},
 		// Custom types (not built-in)
-		{IssueType("pm"), false},      // Custom type from child repo
-		{IssueType("llm"), false},     // Custom type from child repo
-		{IssueType("agent"), false},   // Gas Town custom type
-		{IssueType("convoy"), false},  // Gas Town custom type
-		{IssueType(""), false},        // Empty is not built-in
+		{IssueType("pm"), false},  // Custom type from child repo
+		{IssueType("llm"), false}, // Custom type from child repo
+		{IssueType(""), false},    // Empty is not built-in
 	}
 
 	for _, tt := range tests {