Task Decomposition Skill

Purpose

This skill provides expertise in decomposing specifications into executable, dependency-ordered implementation tasks. It transforms structured requirements and user stories into a concrete work plan that developers can follow sequentially or in parallel. The output is a tasks.md file with numbered tasks, dependency annotations, and full traceability back to the specification.

When It Activates

The skill is triggered when the conversation involves:

• Breaking down a specification into implementation tasks
• Creating or updating a tasks.md file
• Discussing work breakdown, task ordering, or dependency analysis
• Planning implementation phases or sprint work
• Identifying parallelizable work streams

Capabilities

1. Phase-Based Task Ordering

Tasks are organized into five sequential phases:

Phase	Purpose	Examples
Setup	Project scaffolding, tooling, configuration	Init repo, install deps, configure linter
Foundation	Core infrastructure and data layer	Database schema, base models, auth setup
Stories	Feature implementation per user story	Implement US1, US2, US3 endpoints and UI
Integration	Cross-feature wiring, E2E flows	API integration, state management, routing
Finalization	Quality assurance, polish, deployment prep	Testing, docs, CI/CD, performance tuning

Tasks within each phase are ordered by dependency. A later phase never starts before its prerequisites in earlier phases are complete.

2. Task Format

Every task follows this standardized format:

- [ ] T001 [P] [US1] path/to/file.ts -- Description (S) [Spec FR-001]

Where:

• T001 -- Unique task identifier, zero-padded and sequential
• [P] -- Parallelizable marker (present only if the task can run concurrently with others)
• [US1] -- User story reference linking to the specification
• path/to/file.ts -- Primary file or directory affected
• Description -- Concise action description starting with a verb
• (S) -- Size estimate: (S) small, (M) medium, (L) large
• [Spec FR-001] -- Traceability reference back to a specific requirement section

3. Dependency Detection

The skill analyzes tasks to detect and annotate dependencies:

• Explicit dependencies: Task B requires output of Task A (e.g., schema before migration)
• Implicit dependencies: Shared file or module modifications that must be sequenced
• Blocking dependencies: Tasks that gate an entire phase transition

Dependencies are expressed as depends: T001, T003 annotations when non-obvious ordering exists.

4. Parallel Task Identification

Tasks that share no dependencies are marked with the [P] flag, indicating they can be executed concurrently. The skill groups parallelizable tasks together within each phase to maximize throughput.

5. Coverage Validation

After generating the task list, the skill validates coverage:

• Every FR-XXX in the specification maps to at least one task
• Every NFR-XXX has a corresponding task or is addressed by a cross-cutting task
• Every user story (US1, US2, ...) appears in at least one task's [USx] tag

6. Gap Flagging

When coverage validation detects missing mappings, the skill inserts explicit gap markers:

- [ ] T015 [Gap] -- No task covers FR-012 (payment retry logic) [Spec FR-012]

Gap markers are clearly labeled with [Gap] so they can be identified and resolved before implementation begins.

Methodology

The decomposition process follows these steps:

1. Parse Specification: Read spec.md to extract all FR, NFR, user stories, data model entities, and API contracts.
2. Identify Work Units: Map each requirement to one or more concrete implementation actions (file creation, function implementation, configuration change).
3. Assign Phases: Place each work unit into the appropriate phase (Setup, Foundation, Stories, Integration, Finalization).
4. Detect Dependencies: Analyze inter-task relationships and establish ordering constraints.
5. Mark Parallelism: Flag tasks with no dependencies as parallelizable [P].
6. Estimate Sizes: Assign size estimates based on scope and complexity.
7. Validate Coverage: Ensure every requirement is covered by at least one task.
8. Flag Gaps: Insert [Gap] markers for any uncovered requirements.

References

For detailed format specifications, dependency patterns, and phase ordering rules, consult:

• references/task-format.md -- Full task format specification with examples
• references/dependency-patterns.md -- Common dependency patterns and resolution strategies
• references/phase-ordering.md -- Phase definitions, transition criteria, and ordering rules