Planning and task breakdown

Planning and Task Breakdown

Overview

"The plan is the task — 10 minutes upfront prevents hours of rework." Break work into small, ordered, verifiable tasks before writing code. Each task is a vertical slice that leaves the system in a working state.

When to Use

• Before implementing any feature spanning more than 2–3 files
• After writing a spec (follows spec-driven-development)
• When a task feels "too big to start"
• When multiple developers will work on related code

Skip when: The change is a single-file fix with obvious scope.

Core Process

Step 1: Read-Only Analysis

1. Read the spec (SPEC.md) or requirements — do not modify any code
2. Map the codebase:
   • Which modules are involved? (:app, :feature:*, :core:*)
   • Which layers? (UI → ViewModel → UseCase → Repository → DataSource)
   • What existing code can be reused?
3. Identify constraints:
   • Android API level requirements
   • Existing architecture patterns to follow
   • Library versions and compatibility

Step 2: Map Dependencies

4. Draw the dependency graph:
   • Data models → Repository → UseCase → ViewModel → UI
   • Room entities → DAOs → Database migrations
   • Navigation graph changes → Screen composables → ViewModels
5. Identify the critical path — what must exist before other work can start

Step 3: Vertical Slicing

6. Slice vertically, not horizontally:

   Wrong (horizontal):

   • Task 1: Create all Room entities
   • Task 2: Create all DAOs
   • Task 3: Create all repositories
   • Task 4: Create all ViewModels
   • Task 5: Create all screens

   Right (vertical):

   • Task 1: User can view item list (Entity + DAO + Repo + ViewModel + Screen)
   • Task 2: User can create new item (AddScreen + ViewModel + Repo insert)
   • Task 3: User can edit existing item (EditScreen + ViewModel + Repo update)
   • Task 4: User can delete item (swipe-to-delete + Repo delete + undo)

7. Each slice must:

   • Deliver observable functionality
   • Be testable in isolation
   • Leave ./gradlew build passing

Step 4: Write Structured Tasks

8. Create tasks/plan.md with the dependency graph and approach
9. Create tasks/todo.md with tasks in execution order:

## Tasks

### Task 1: [Short description]
**Files:** `feature/src/.../ItemListScreen.kt`, `core/data/src/.../ItemDao.kt`
**Acceptance criteria:**
- Item list loads from Room database
- Empty state shown when no items exist
- Loading state shown during fetch
**Verification:**
- [ ] `./gradlew test` passes
- [ ] `./gradlew assembleDebug` succeeds
- [ ] Compose Preview renders correctly

Step 5: Order by Dependencies

10. Sequence tasks so each builds on the previous
11. Add checkpoints every 2–3 tasks: run full test suite, review with human
12. Flag risks on tasks with uncertainty — mark as "spike" if investigation needed

Task Sizing Guide

Size	Files	Duration	Action
Small	1–2	< 30 min	Execute directly
Medium	3–5	30–60 min	Execute with checkpoint
Large	6+	> 60 min	Split further

Split when: task touches >2 independent subsystems, or acceptance criteria exceed 5 items.

Common Rationalizations

Shortcut	Why It Fails
"I'll plan as I go"	Without a task list, you lose track of scope and dependencies. Rework multiplies.
"The spec is the plan"	Specs describe what. Plans describe how and in what order.
"Planning takes too long"	A 10-minute plan prevents hours of backtracking.
"I know this codebase, I don't need a plan"	Plans catch dependency gaps that familiarity masks.

Red Flags

• Implementing without a written task list
• Tasks missing acceptance criteria
• No verification steps on tasks
• Tasks spanning >5 files without splitting
• No checkpoints between tasks
• Horizontal slicing (all DAOs, then all repos, then all VMs)

Verification

• tasks/plan.md exists with dependency graph
• tasks/todo.md exists with ordered tasks
• Every task has acceptance criteria and verification steps
• Tasks are vertically sliced (each delivers observable functionality)
• No task exceeds "Large" sizing without justification
• Checkpoints placed every 2–3 tasks
• Human has reviewed the plan before implementation starts