feat(epic): add Working Model as required section for epics

Epics now require a "Working Model" section in their description,
in addition to "Success Criteria". This provides clear guidance on
HOW the epic will be executed:

- Owner role: Coordinator vs Implementer
- Delegation target: Polecats, crew, external
- Review process: Approval gates

Closes gt-0lp

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

claude-plugin/commands/epic.md

@@ -24,3 +24,25 @@ Manage epics (large features composed of multiple issues).
 4. Auto-close when done: `bd epic close-eligible`
 
 Epics use parent-child dependencies to track subtasks.
+
+## Epic Template Sections
+
+Epics require two sections in their description:
+
+### Success Criteria
+Define high-level criteria for epic completion. What does "done" look like?
+
+### Working Model
+Define HOW the epic will be executed:
+
+- **Owner role**: Is the assignee a Coordinator (decomposes and delegates) or Implementer (does hands-on work)?
+- **Delegation target**: Who does the work? Polecats? Other crew? External contributors?
+- **Review process**: Who approves completed subtasks? What gates must pass?
+
+Example:
+```markdown
+## Working Model
+- **Owner role**: Coordinator - decompose into subtasks and sling to polecats
+- **Delegation target**: Polecat swarm (3-5 workers)
+- **Review process**: Refinery MQ for each subtask, owner approval for epic closure
+```

internal/types/types.go

@@ -560,6 +560,7 @@ func (t IssueType) RequiredSections() []RequiredSection {
 	case TypeEpic:
 		return []RequiredSection{
 			{Heading: "## Success Criteria", Hint: "Define high-level success criteria"},
+			{Heading: "## Working Model", Hint: "Owner role (coordinator/implementer), delegation target, review process"},
 		}
 	default:
 		// Chore and custom types have no required sections

internal/types/types_test.go

@@ -579,7 +579,7 @@ func TestIssueTypeRequiredSections(t *testing.T) {
 		{TypeBug, 2, "## Steps to Reproduce"},
 		{TypeFeature, 1, "## Acceptance Criteria"},
 		{TypeTask, 1, "## Acceptance Criteria"},
-		{TypeEpic, 1, "## Success Criteria"},
+		{TypeEpic, 2, "## Success Criteria"},
 		{TypeChore, 0, ""},
 		// Gas Town types are now custom and have no required sections
 		{IssueType("message"), 0, ""},

internal/validation/template_test.go

@@ -97,19 +97,34 @@ Widget displays correctly`,
 
 		// Epic type tests
 		{
-			name:      "epic with success criteria",
+			name:      "epic with all sections",
 			issueType: types.TypeEpic,
 			description: `Big project
 
 ## Success Criteria
 - Project ships
-- Users happy`,
+- Users happy
+
+## Working Model
+- Owner role: Coordinator
+- Delegation target: Polecats
+- Review process: Refinery MQ`,
 			wantErr: false,
 		},
 		{
-			name:        "epic missing success criteria",
+			name:        "epic missing all sections",
 			issueType:   types.TypeEpic,
 			description: "Do everything",
+			wantErr:     true,
+			wantMissing: 2,
+		},
+		{
+			name:      "epic missing working model",
+			issueType: types.TypeEpic,
+			description: `Big project
+
+## Success Criteria
+- Project ships`,
 			wantErr:     true,
 			wantMissing: 1,
 		},