Product Requirements Document (PRD)

1. Executive Summary

1.1 Product Name

TBD (to be determined)

1.2 Product Vision

A web-based Gantt chart creator that makes timeline visualization effortless, beautiful, and accessible to everyone - no account required, no server dependency, just instant productivity.

1.3 Problem Statement

Existing Gantt chart tools are either:

Too complex (enterprise PM tools with resource planning, billing, etc.)
Require accounts and subscriptions
Store data on servers (privacy/security concerns)
Slow to create simple visualizations
Produce ugly charts that need extensive styling

1.4 Solution

A client-side web application that:

Works immediately without registration
Creates beautiful charts by default
Saves/loads from single portable files
Includes full version history with time-travel UI
Exports to multiple formats for sharing

2. Goals and Objectives

2.1 Primary Goals

Speed: Create a basic Gantt chart in under 2 minutes
Beauty: Professional appearance with zero styling effort
Simplicity: Intuitive interface requiring no training
Privacy: Zero server storage, complete client-side operation
Portability: Single-file format for easy backup and sharing

2.2 Success Metrics

Time to first chart: < 2 minutes for new users
User satisfaction with default styling: > 80% positive feedback
File format adoption: Ability to open files across different browsers/devices
Export quality: Professional-grade PDF/SVG/PNG output

3. Target Audience

3.1 Primary Users

Freelancers: Visualizing project timelines for clients
Small Team Leads: Planning sprints and project phases
Students: Academic project planning and presentations
Consultants: Creating timeline proposals and reports

3.2 User Characteristics

Varying technical expertise (from beginner to advanced)
Need quick results without learning curve
Value aesthetics and presentation quality
Privacy-conscious (prefer not sharing data with servers)
Work primarily on desktop/laptop computers

4. Core Requirements

4.1 Functional Requirements

4.1.1 Chart Creation (MUST HAVE)

FR-001: Users can create new blank Gantt charts instantly
FR-002: Users can add tasks with name, start date, end date
FR-003: Users can edit task properties inline
FR-004: Users can delete tasks
FR-005: Users can reorder tasks (drag and drop)
FR-006: Users can create task dependencies with visual arrows and offset (lag days)
FR-007: Users can add milestones (zero-duration markers)
FR-008: Charts automatically calculate and display timeline scale
FR-009: Users can copy and paste tasks (with dependencies if multi-select)
FR-009a: Users can multi-select tasks for bulk operations
FR-009b: Users can organize tasks into collapsible groups/phases with optional summary bars

4.1.2 File Operations (MUST HAVE)

FR-010: Users can save current chart to local file
FR-011: Users can open/import previously saved files
FR-012: File format preserves all chart data including history
FR-013: Files are human-readable (JSON-based)
FR-014: Files include metadata (created date, modified date, version)

4.1.3 Version History (MUST HAVE)

FR-020: System automatically saves every change to history
FR-021: Users can navigate history with timeline slider
FR-022: Visual preview updates in real-time while scrubbing timeline
FR-023: Users can create named snapshots at important points
FR-024: Snapshots appear as markers on timeline slider
FR-025: Users can restore to any point in history

4.1.4 Export Functionality (MUST HAVE)

FR-030: Users can export chart to PDF format with multiple customization options
FR-031: Users can export chart to SVG format with multiple customization options
FR-032: Users can export chart to PNG format with multiple customization options
FR-033: Export settings include: page size, orientation, resolution, date range, background
FR-034: Export maintains visual quality and styling

4.1.5 Customization (SHOULD HAVE)

FR-040: Users can adjust color scheme/theme
FR-041: Users can customize task colors individually
FR-042: Users can adjust timeline view (days/weeks/months)
FR-043: Users can zoom in/out on timeline with fit-to-screen reset button
FR-044: Users can show/hide weekends
FR-045: Users can adjust UI density/compactness (compact/normal/comfortable)
FR-046: Users can add custom labels/notes to tasks
FR-047: Users can set preferred date format
FR-048: Users can set first day of week (Sunday/Monday)
FR-049: Users can configure task name display position (in bar/above/below/smart)
FR-050: Users can optionally show/hide history timeline slider
FR-051: Users can optionally show timeline at both top and bottom of chart

4.1.6 Validation and Auto-features (SHOULD HAVE)

FR-060: System validates date logic (end after start)
FR-061: System auto-adjusts dependent tasks when parent changes
FR-062: System displays vertical line showing today's date on timeline
FR-063: System warns about circular dependencies
FR-064: System auto-saves to browser storage (recovery)
FR-065: Timeline labels automatically adjust based on zoom level (years→months→weeks→days)
FR-066: System can collapse dependent tasks for compact visualization

4.2 Non-Functional Requirements

4.2.1 Performance

NFR-001: Chart renders in < 500ms for up to 100 tasks
NFR-002: Chart renders in < 2s for up to 1000 tasks
NFR-003: History navigation responds in < 100ms
NFR-004: File save/load completes in < 1s for typical charts

4.2.2 Usability

NFR-010: Zero learning curve for basic operations
NFR-011: All features discoverable through UI
NFR-012: Keyboard shortcuts for common operations
NFR-013: Undo/redo support for all actions
NFR-014: Responsive design for laptop/desktop screens (1280px+)

4.2.3 Compatibility

NFR-020: Works in Chrome, Firefox, Safari, Edge (latest 2 versions)
NFR-021: Files compatible across all browsers
NFR-022: No server/backend required
NFR-023: Works offline after initial load

4.2.4 Security & Privacy

NFR-030: No data transmitted to servers
NFR-031: No tracking or analytics without explicit consent
NFR-032: All processing happens client-side
NFR-033: No authentication/login required

4.2.5 Accessibility

NFR-040: Keyboard navigation for all features
NFR-041: Screen reader compatible (WCAG 2.1 AA)
NFR-042: Sufficient color contrast ratios
NFR-043: Resizable text without breaking layout

5. Feature Prioritization

5.1 MoSCoW Method

MUST HAVE (MVP)

Basic task creation/editing/deletion
Task dependencies with visual arrows and offset
Copy/paste tasks with multi-select
Task groups/phases with collapsible sections
Save/load to JSON file
Version history with timeline slider
Export to PNG
Today marker (vertical line)
Zoom and pan timeline with fit button
Beautiful default styling
Offline capability

SHOULD HAVE (V1.0)

Export to PDF and SVG with customization options
Named snapshots
Color customization
Milestones
Keyboard shortcuts
Undo/redo
UI density/compactness settings
Date format and first day of week settings
Task name position configuration
Show/hide history timeline option
Optional duplicate timeline at bottom
Collapse dependent tasks optimization

COULD HAVE (Future)

Templates (pre-built chart styles)
Multiple chart views (list view, calendar view)
Task notes/descriptions
File attachments per task
Print optimization
Import from other formats (MS Project, CSV)
Mobile-responsive version

WON'T HAVE (Initially, but possible future)

Login/authentication (future: for sharing features)
Server-side storage (future: for collaboration)
Real-time collaboration (future: with login)
Share charts with/without edit access (future: with login)
Mobile native app (future: maybe)

WON'T HAVE (Out of Scope Permanently)

Resource management
Cost/budget tracking
Time tracking
Team management

6. User Interface Requirements

6.1 Main Interface Sections

Top Toolbar: File operations, export, undo/redo, view controls
Left Panel: Task list with inline editing
Main Canvas: Visual Gantt chart with timeline
Bottom Timeline Slider: History navigation
Right Panel (collapsible): Styling and customization options

6.2 Key Interactions

Click to select tasks
Double-click to edit task name
Drag task bars to adjust dates
Drag task ends to resize duration
Drag between tasks to create dependencies
Drag on timeline background to pan/navigate the project timeline
Right-click for context menus
Scroll to pan timeline horizontally
Zoom with mouse wheel/pinch gesture
Fit button to reset zoom and display entire project

7. Data Requirements

7.1 File Format

Format: JSON
Extension: .ownchart or .ownchartflow
Encoding: UTF-8
Compression: Optional (gzip for large files)

7.2 Data to Store

Project-Specific Settings (stored in project file):

Chart metadata (name, created date, modified date)
Task list (name, start, end, color, dependencies, groups)
Task groups/phases with hierarchy
Milestones
Complete change history
Named snapshots
Project view settings (zoom level, visible date range)
Application version (for format compatibility)

Application Settings (stored in browser only):

UI density/compactness preference
Default color palette
Date format preference
First day of week
Task name display position
Show/hide history timeline
Show timeline at top and/or bottom
Theme preference
Keyboard shortcuts (if customizable)

8. Technical Constraints

8.1 Architecture Constraints

Client-side only (no backend)
Single-page application (SPA)
No external data storage
No user authentication

8.2 Technology Constraints

Must work in modern browsers (ES6+)
Must not require installation
Must be hostable as static files

8.3 Scalability Constraints

Support up to 1000 tasks per chart (performance target)
File size reasonable (< 5MB for typical charts)
History limited to last 1000 changes (configurable)

9. Dependencies and Assumptions

9.1 Dependencies

Modern web browser with JavaScript enabled
Local file system access (for save/open)
Canvas/SVG support for rendering

9.2 Assumptions

Users have basic computer literacy
Users understand Gantt chart concepts
Users work primarily on desktop/laptop devices
Users have stable browsers (not ancient IE)

10. Future Considerations & Extensibility

See EXTENSIBILITY_ARCHITECTURE.md for complete architectural details.

10.1 Features Enabled by Extensible Architecture

The MVP architecture includes extensibility foundations that enable future features without breaking changes:

Immediate Benefits (V1.1):

Custom Fields: Users can add their own metadata fields to tasks (Priority, Status, Client, etc.)
Multi-Project Management: Switch between multiple Gantt charts with project switcher
Import/Export Adapters: CSV, MS Project XML import/export capabilities

Mid-Term Features (V1.2-V1.5):

Alternative Views: Kanban board, Calendar view, List view (same data, different visualizations)
Resource Management: Assign team members, track workload, balance resources
Plugin System: Community plugins for custom features
Advanced Dependencies: Start-to-Start, Finish-to-Finish, Start-to-Finish relationships

Long-Term Features (V2.0):

Collaboration: Real-time editing, comments, mentions (optional cloud backend)
Advanced Integrations: Webhooks, REST API, third-party tool integrations
Mobile Editing: Full touch-based editing on tablets and phones

10.2 Architectural Decisions Made for Extensibility

Data Model Extensibility:

Task interface includes customFields map for user-defined metadata
Optional fields for collaboration: assignedTo, createdBy, lastModifiedBy
Optional fields for resources: estimatedHours, actualHours
All extensibility fields are optional and backward compatible

File Format Versioning:

Explicit fileVersion and schemaVersion fields for migration tracking
Unknown fields preserved when loading files from future versions
Migration system for upgrading old files to new formats

Plugin Architecture:

Event bus for subscribing to application events
Plugin registration API for third-party extensions
View abstraction layer for alternative visualizations

Storage Flexibility:

Multi-project IDs in data model
Storage adapter pattern (can swap IndexedDB → Cloud Storage)
Per-project auto-save and metadata

10.3 Avoiding Common Pitfalls

What we're doing RIGHT:

✅ Designing extensible data model from day one
✅ File format versioning and migration system
✅ Event-driven architecture for plugins
✅ View layer decoupled from data
✅ Unknown field preservation for forward compatibility

What we're avoiding:

❌ Tight coupling between data and UI that prevents alternative views
❌ Hard-coded task fields that can't be extended
❌ File format with no version tracking (breaks compatibility)
❌ Monolithic architecture that can't support plugins
❌ Single-project assumption baked into storage

10.4 Implementation Timeline

Phase	Extensibility Milestone	Features Unlocked
Phase 1 (MVP)	Data model includes all extensibility fields	Foundation ready
V1.1	Custom fields UI, Multi-project UI	Users can extend tasks
V1.2	Plugin API, CSV adapter	Community extensions
V1.5	Alternative views (List, Calendar)	Multiple visualizations
V2.0	Collaboration backend, Full plugin system	Real-time collaboration, marketplace

11. Open Questions

File Format Details: Should we support import from other formats (MS Project, CSV)? → Defer to V2.0
Export Settings: What customization options for PDF/SVG/PNG exports? → ✓ Resolved: Multiple options (see FR-033)
Collaboration: Should read-only sharing be in MVP or later? → Defer to future with login feature
Templates: Should we include sample/starter templates? → Defer to V1.x
Localization: Multi-language support priority? → Defer to V2.0
Auto-backup: Frequency and management of browser-based auto-saves? → Default 30 seconds, configurable
Group Summary Bar Display: Should summary bars be shown by default or user-toggleable? → User-toggleable setting
Collapsed Dependencies: When should dependent tasks collapse automatically? → Manual collapse only, not automatic
History Timeline: Shown by default or hidden? → Shown by default, user can hide via setting
Export Date Range: Should we support exporting only a portion of the timeline? → Yes, include in export options

12. Success Criteria

The product will be considered successful when:

A non-technical user can create a presentable Gantt chart in under 5 minutes
Users prefer the default styling over custom styling 70%+ of the time
File format is stable and forward-compatible
Export quality matches or exceeds commercial tools
Zero critical bugs related to data loss
Positive user feedback on simplicity and speed

13. Timeline and Milestones

See ROADMAP.md for detailed development phases.

Target Milestones:

Concept completion: 2 weeks
MVP development: 8-12 weeks
Beta testing: 2-4 weeks
V1.0 release: 3-4 months from start

Document Version: 1.3 Last Updated: 2025-12-23 Owner: Product Concept Team Status: Draft - Updated with competitive analysis insights

Recent Updates (v1.3):

Added Section 11: Competitive Analysis Insights
Enhanced data model with task types, hierarchy, and baselines
Feature prioritization based on competitive analysis
Strategic decision to build independently
Updated technical constraints with performance targets
Reference to COMPETITIVE_ANALYSIS.md for detailed findings

Previous Updates (v1.2):

Added Section 10: Future Considerations & Extensibility
Outlined architectural decisions for extensibility
Mapped features enabled by extensible architecture
Added implementation timeline for extensibility features
Reference to EXTENSIBILITY_ARCHITECTURE.md for technical details

Previous Updates (v1.1):

Updated with additional features (copy/paste, grouping, compactness, settings)

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