Agent skill
timeline-planning
Generate Mermaid Gantt charts for project timelines with phases, dependencies, and milestones
Install this agent skill to your Project
npx add-skill https://github.com/britt/claude-code-skills/tree/main/skills/timeline-planning
SKILL.md
Timeline Planning Skill
Generate Mermaid Gantt charts that visualize project timelines, task scheduling, phases, and milestones based on GitHub issues and their estimates.
When to Use
Activate this skill when:
- User asks "what would the timeline look like?"
- User says "create a Gantt chart", "show me the project schedule"
- After issue decomposition to visualize scheduling
- During sprint planning to allocate work
Mermaid Gantt Syntax
Basic Structure
gantt
title Project Timeline
dateFormat YYYY-MM-DD
section Phase 1
Task A :a, 2025-01-15, 2d
Task B :b, after a, 3d
section Phase 2
Task C :c, after b, 2d
Key Elements
title- Chart titledateFormat- How dates are parsedsection- Groups related tasks- Task format:
Name :id, start, duration
Estimate to Duration Conversion
Convert T-shirt size estimates to days:
| Estimate | Duration | Notes |
|---|---|---|
| Small | 1d | Single-day task |
| Medium | 3d | Few days of work |
| Large | 5d | Almost a week |
| XL | 8d | Full week+ |
Adjust based on:
- Team velocity
- Complexity indicators
- Buffer for unknowns
Task States
| Modifier | Meaning | Example |
|---|---|---|
done |
Completed | Task A :done, a, 2025-01-15, 2d |
active |
In progress | Task B :active, b, after a, 3d |
crit |
Critical path | Task C :crit, c, after b, 5d |
milestone |
Milestone | MVP :milestone, m, after c, 0d |
Timeline Patterns
Linear Project
gantt
title API Development
dateFormat YYYY-MM-DD
section Setup
Project initialization :a, 2025-01-15, 1d
Database setup :b, after a, 2d
section Development
User endpoints :c, after b, 3d
Auth endpoints :d, after c, 3d
section Testing
Unit tests :e, after d, 2d
Integration tests :f, after e, 2d
Parallel Workstreams
gantt
title Full Stack Development
dateFormat YYYY-MM-DD
section Backend
API Design :a, 2025-01-15, 2d
API Implementation :b, after a, 5d
section Frontend
UI Design :c, 2025-01-15, 3d
UI Implementation :d, after c, 5d
section Integration
Connect Frontend-Backend :e, after b d, 3d
End-to-end tests :f, after e, 2d
With Milestones
gantt
title Release Timeline
dateFormat YYYY-MM-DD
section Phase 1
Core features :a, 2025-01-15, 10d
Alpha Release :milestone, m1, after a, 0d
section Phase 2
Additional features :b, after m1, 7d
Beta Release :milestone, m2, after b, 0d
section Phase 3
Polish and fixes :c, after m2, 5d
Production Release :milestone, m3, after c, 0d
With Critical Path
gantt
title Project with Critical Path
dateFormat YYYY-MM-DD
section Critical Path
Database design :crit, a, 2025-01-15, 2d
Core API :crit, b, after a, 5d
Integration :crit, c, after b, 3d
section Parallel Work
Documentation :d, 2025-01-15, 10d
UI polish :e, after a, 5d
Timeline Generation Process
Step 1: Gather Issues
Gather the following from project issues:
- Issue titles
- Estimates or labels indicating size
- Dependencies or blocking relationships
Step 2: Determine Start Date
- Use today's date as default start
- Or ask user for preferred start date
- Consider sprint boundaries
Step 3: Convert Estimates
Transform issue estimates to durations:
#101 [Small] → 1d
#102 [Medium] → 3d
#103 [Large] → 5d
Step 4: Respect Dependencies
Order tasks based on blocking:
#101 → start immediately
#102 blocked by #101 → after #101
#103 blocked by #102 → after #102
Step 5: Group into Phases
Organize tasks into logical sections:
- Setup/Foundation
- Core Features
- Testing
- Polish
Step 6: Generate Gantt Chart
Create the Mermaid syntax with all tasks, dependencies, and phases.
Date Formats
| Format | Example |
|---|---|
YYYY-MM-DD |
2025-01-15 |
after id |
after a |
Nd |
3d - duration in days |
Best Practices
- Use sections - Group related tasks for clarity
- Show dependencies - Use
after idto chain tasks - Mark milestones - Highlight key deliverables
- Indicate critical path - Use
:critfor must-do-first tasks - Keep titles short - Fit in the chart view
- Add buffer - Include slack for unknowns
Example Output
For a set of issues about user authentication:
gantt
title User Authentication System
dateFormat YYYY-MM-DD
section Foundation
Setup auth module :a, 2025-01-20, 1d
Database schema :b, after a, 1d
section Core Auth
Registration endpoint :c, after b, 3d
Login endpoint :d, after b, 3d
Password reset :e, after c, 2d
section Security
JWT implementation :f, after d, 2d
Rate limiting :g, after f, 1d
section Testing
Unit tests :h, after e g, 2d
Integration tests :i, after h, 2d
section Milestone
Auth Complete :milestone, m1, after i, 0d
Handling Edge Cases
No Estimates
If issues lack estimates:
- Use Medium (3d) as default
- Flag for user to review
Circular Dependencies
If dependencies form a loop:
- Error and ask user to resolve
- Cannot generate valid timeline
Too Many Tasks
If > 20 tasks:
- Group into summary tasks
- Suggest breaking into phases
After Generating Timeline
- Show total project duration
- Identify the end date
- Flag if timeline exceeds any stated deadlines
- Offer to save to project notes
- Suggest adding milestones if missing
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