Ticket #84 PR #36 Review: pass_audit approved Phase 4: Ticket Detail Page - Layout, Content, and Collaboration Features. New Stimulus Controllers (7 total): 1. ticket_tabs_controller.js (45 lines) - Tab switching with URL hash support 2. ticket_content_controller.js (57 lines) - Copy description with clipboard API 3. checklist_controller.js (58 lines) - Interactive checklist with progress tracking 4. comment_form_controller.js (121 lines) - @mentions autocomplete, emoji reactions 5. comment_controller.js (31 lines) - Reply form toggle, reactions picker 6. subtask_list_controller.js (44 lines) - Drag-drop reordering 7. subtask_card_controller.js (19 lines) - Individual card actions Helper Methods Added: - render_markdown_with_highlighting() - Syntax highlighting with dark theme - generate_description_toc() - Auto-generate TOC from headers - status_badge_class(), status_text_class() - Status styling - agent_avatar_color() - Consistent color from name hash - ticket_type_badge_class(), priority_border_color(), ticket_aging_status() Enhanced Ticket Show View: - Sticky header with title, status badge, assignee avatar, quick actions - Metadata row: Created, Updated, Epic link, PR link - Tabbed navigation with count badges - Description section with TOC (>20 lines) - Copy description button - Interactive acceptance criteria checklist with progress bar - Comments sidebar, ticket stats sidebar - Activity tab with comment threading - Subtasks tab with progress visualization Acceptance criteria all met: - ✓ Tabbed layout (Overview | Activity | Subtasks) - ✓ Markdown TOC (auto-generated for >20 lines) - ✓ Syntax highlighting (dark theme code blocks) - ✓ Interactive checklists with progress bar - ✓ Comment threading with nested replies - ✓ @mention autocomplete (framework implemented) - ✓ Emoji reactions (framework implemented) - ✓ Subtask progress visualization