Planning and task breakdown

Planning and Task Breakdown

Overview

Decompose work into small, verifiable tasks with explicit acceptance criteria. Good task breakdown is the difference between an agent that completes work reliably and one that produces a tangled mess. Every task should be small enough to implement, test, and verify in a single focused session.

When to Use

• You have a spec and need to break it into implementable units
• A task feels too large or vague to start
• Work needs to be parallelized across multiple agents or sessions
• You need to communicate scope to a human
• The implementation order isn't obvious

When NOT to use: Single-file changes with obvious scope, or when the spec already contains well-defined tasks.

The Planning Process

Step 1: Enter Plan Mode

Before writing any code, operate in read-only mode:

• Read the spec and relevant codebase sections
• Identify existing patterns and conventions
• Map dependencies between components
• Note risks and unknowns

Do NOT write code during planning. The output is a plan document, not implementation.

Step 2: Identify the Dependency Graph

Map what depends on what:

Database schema
    │
    ├── API models/types
    │       │
    │       ├── API endpoints
    │       │       │
    │       │       └── Frontend API client
    │       │               │
    │       │               └── UI components
    │       │
    │       └── Validation logic
    │
    └── Seed data / migrations

Implementation order follows the dependency graph bottom-up: build foundations first.

Step 3: Slice Vertically

Instead of building all the database, then all the API, then all the UI — build one complete feature path at a time:

Bad (horizontal slicing):

Task 1: Build entire database schema
Task 2: Build all API endpoints
Task 3: Build all UI components
Task 4: Connect everything

Good (vertical slicing):

Task 1: User can create an account (schema + API + UI for registration)
Task 2: User can log in (auth schema + API + UI for login)
Task 3: User can export a skill (skill schema + API + UI for export)

Each vertical slice delivers working, testable functionality.

Step 4: Write Tasks

Each task follows this structure:

## Task [N]: [Short descriptive title]

**Description:** One paragraph explaining what this task accomplishes.

**Acceptance criteria:**
- [ ] [Specific, testable condition]
- [ ] [Specific, testable condition]

**Verification:**
- [ ] Tests pass: `pytest tests/ -k "test_name"`
- [ ] Build succeeds
- [ ] Manual check: [description of what to verify]

**Dependencies:** [Task numbers this depends on, or "None"]

**Files likely touched:**
- `api/app/path/to/file.py`
- `web/components/path/to/component.tsx`

**Estimated scope:** [Small: 1-2 files | Medium: 3-5 files | Large: 5+ files]

Step 5: Order and Checkpoint

Arrange tasks so that:

1. Dependencies are satisfied (build foundation first)
2. Each task leaves the system in a working state
3. Verification checkpoints occur after every 2-3 tasks
4. High-risk tasks are early (fail fast)

Add explicit checkpoints:

## Checkpoint: After Tasks 1-3
- [ ] All tests pass
- [ ] Application builds without errors
- [ ] Core user flow works end-to-end
- [ ] Review with human before proceeding

Task Sizing Guidelines

Size	Files	Scope	Example
XS	1	Single function or config change	Add a validation rule
S	1-2	One component or endpoint	Add a new API endpoint
M	3-5	One feature slice	Skill export flow
L	5-8	Multi-component feature	Search with filtering and pagination
XL	8+	Too large — break it down further	—

If a task is L or larger, break it into smaller tasks. An agent performs best on S and M tasks.

When to break a task down further:

• It would take more than one focused session
• You cannot describe the acceptance criteria in 3 or fewer bullet points
• It touches two or more independent subsystems
• You find yourself writing "and" in the task title

Common Rationalizations

Rationalization	Reality
"I'll figure it out as I go"	That's how you end up with a tangled mess and rework. 10 minutes of planning saves hours.
"The tasks are obvious"	Write them down anyway. Explicit tasks surface hidden dependencies and forgotten edge cases.
"Planning is overhead"	Planning is the task. Implementation without a plan is just typing.
"I can hold it all in my head"	Context windows are finite. Written plans survive session boundaries.

Red Flags

• Starting implementation without a written task list
• Tasks that say "implement the feature" without acceptance criteria
• No verification steps in the plan
• All tasks are XL-sized
• No checkpoints between tasks
• Dependency order isn't considered

Verification

Before starting implementation, confirm:

• Every task has acceptance criteria
• Every task has a verification step
• Task dependencies are identified and ordered correctly
• No task touches more than ~5 files
• Checkpoints exist between major phases
• The human has reviewed and approved the plan