---
name: decompose
description: |
  Decompose planned components into atomic implementable tasks with bootstrap structure plan.
  4-step workflow: bootstrap structure plan, component task decomposition, blackbox test task decomposition, and cross-task verification.
  Supports full decomposition (_docs/ structure), single component mode, and tests-only mode.
  Trigger phrases:
  - "decompose", "decompose features", "feature decomposition"
  - "task decomposition", "break down components"
  - "prepare for implementation"
  - "decompose tests", "test decomposition"
category: build
tags: [decomposition, tasks, dependencies, jira, implementation-prep]
disable-model-invocation: true
---

# Task Decomposition

Decompose planned components into atomic, implementable task specs with a bootstrap structure plan through a systematic workflow. All tasks are named with their Jira ticket ID prefix in a flat directory.

## Core Principles

- **Atomic tasks**: each task does one thing; if it exceeds 5 complexity points, split it
- **Behavioral specs, not implementation plans**: describe what the system should do, not how to build it
- **Flat structure**: all tasks are Jira-ID-prefixed files in TASKS_DIR — no component subdirectories
- **Save immediately**: write artifacts to disk after each task; never accumulate unsaved work
- **Jira inline**: create Jira ticket immediately after writing each task file
- **Ask, don't assume**: when requirements are ambiguous, ask the user before proceeding
- **Plan, don't code**: this workflow produces documents and Jira tasks, never implementation code

## Context Resolution

Determine the operating mode based on invocation before any other logic runs.

**Default** (no explicit input file provided):
- DOCUMENT_DIR: `_docs/02_document/`
- TASKS_DIR: `_docs/02_tasks/`
- Reads from: `_docs/00_problem/`, `_docs/01_solution/`, DOCUMENT_DIR
- Runs Step 1 (bootstrap) + Step 2 (all components) + Step 3 (blackbox tests) + Step 4 (cross-verification)

**Single component mode** (provided file is within `_docs/02_document/` and inside a `components/` subdirectory):
- DOCUMENT_DIR: `_docs/02_document/`
- TASKS_DIR: `_docs/02_tasks/`
- Derive component number and component name from the file path
- Ask user for the parent Epic ID
- Runs Step 2 (that component only, appending to existing task numbering)

**Tests-only mode** (provided file/directory is within `tests/`, or `DOCUMENT_DIR/tests/` exists and input explicitly requests test decomposition):
- DOCUMENT_DIR: `_docs/02_document/`
- TASKS_DIR: `_docs/02_tasks/`
- TESTS_DIR: `DOCUMENT_DIR/tests/`
- Reads from: `_docs/00_problem/`, `_docs/01_solution/`, TESTS_DIR
- Runs Step 1t (test infrastructure bootstrap) + Step 3 (blackbox test decomposition) + Step 4 (cross-verification against test coverage)
- Skips Step 1 (project bootstrap) and Step 2 (component decomposition) — the codebase already exists

Announce the detected mode and resolved paths to the user before proceeding.

## Input Specification

### Required Files

**Default:**

| File | Purpose |
|------|---------|
| `_docs/00_problem/problem.md` | Problem description and context |
| `_docs/00_problem/restrictions.md` | Constraints and limitations |
| `_docs/00_problem/acceptance_criteria.md` | Measurable acceptance criteria |
| `_docs/01_solution/solution.md` | Finalized solution |
| `DOCUMENT_DIR/architecture.md` | Architecture from plan skill |
| `DOCUMENT_DIR/system-flows.md` | System flows from plan skill |
| `DOCUMENT_DIR/components/[##]_[name]/description.md` | Component specs from plan skill |
| `DOCUMENT_DIR/tests/` | Blackbox test specs from plan skill |

**Single component mode:**

| File | Purpose |
|------|---------|
| The provided component `description.md` | Component spec to decompose |
| Corresponding `tests.md` in the same directory (if available) | Test specs for context |

**Tests-only mode:**

| File | Purpose |
|------|---------|
| `TESTS_DIR/environment.md` | Test environment specification (Docker services, networks, volumes) |
| `TESTS_DIR/test-data.md` | Test data management (seed data, mocks, isolation) |
| `TESTS_DIR/blackbox-tests.md` | Blackbox functional scenarios (positive + negative) |
| `TESTS_DIR/performance-tests.md` | Performance test scenarios |
| `TESTS_DIR/resilience-tests.md` | Resilience test scenarios |
| `TESTS_DIR/security-tests.md` | Security test scenarios |
| `TESTS_DIR/resource-limit-tests.md` | Resource limit test scenarios |
| `TESTS_DIR/traceability-matrix.md` | AC/restriction coverage mapping |
| `_docs/00_problem/problem.md` | Problem context |
| `_docs/00_problem/restrictions.md` | Constraints for test design |
| `_docs/00_problem/acceptance_criteria.md` | Acceptance criteria being verified |

### Prerequisite Checks (BLOCKING)

**Default:**
1. DOCUMENT_DIR contains `architecture.md` and `components/` — **STOP if missing**
2. Create TASKS_DIR if it does not exist
3. If TASKS_DIR already contains task files, ask user: **resume from last checkpoint or start fresh?**

**Single component mode:**
1. The provided component file exists and is non-empty — **STOP if missing**

**Tests-only mode:**
1. `TESTS_DIR/blackbox-tests.md` exists and is non-empty — **STOP if missing**
2. `TESTS_DIR/environment.md` exists — **STOP if missing**
3. Create TASKS_DIR if it does not exist
4. If TASKS_DIR already contains task files, ask user: **resume from last checkpoint or start fresh?**

## Artifact Management

### Directory Structure

```
TASKS_DIR/
├── [JIRA-ID]_initial_structure.md
├── [JIRA-ID]_[short_name].md
├── [JIRA-ID]_[short_name].md
├── ...
└── _dependencies_table.md
```

**Naming convention**: Each task file is initially saved with a temporary numeric prefix (`[##]_[short_name].md`). After creating the Jira ticket, rename the file to use the Jira ticket ID as prefix (`[JIRA-ID]_[short_name].md`). For example: `01_initial_structure.md` → `AZ-42_initial_structure.md`.

### Save Timing

| Step | Save immediately after | Filename |
|------|------------------------|----------|
| Step 1 | Bootstrap structure plan complete + Jira ticket created + file renamed | `[JIRA-ID]_initial_structure.md` |
| Step 1t | Test infrastructure bootstrap complete + Jira ticket created + file renamed | `[JIRA-ID]_test_infrastructure.md` |
| Step 2 | Each component task decomposed + Jira ticket created + file renamed | `[JIRA-ID]_[short_name].md` |
| Step 3 | Each blackbox test task decomposed + Jira ticket created + file renamed | `[JIRA-ID]_[short_name].md` |
| Step 4 | Cross-task verification complete | `_dependencies_table.md` |

### Resumability

If TASKS_DIR already contains task files:

1. List existing `*_*.md` files (excluding `_dependencies_table.md`) and count them
2. Resume numbering from the next number (for temporary numeric prefix before Jira rename)
3. Inform the user which tasks already exist and are being skipped

## Progress Tracking

At the start of execution, create a TodoWrite with all applicable steps. Update status as each step/component completes.

## Workflow

### Step 1t: Test Infrastructure Bootstrap (tests-only mode only)

**Role**: Professional Quality Assurance Engineer
**Goal**: Produce `01_test_infrastructure.md` — the first task describing the test project scaffold
**Constraints**: This is a plan document, not code. The `/implement` skill executes it.

1. Read `TESTS_DIR/environment.md` and `TESTS_DIR/test-data.md`
2. Read problem.md, restrictions.md, acceptance_criteria.md for domain context
3. Document the test infrastructure plan using `templates/test-infrastructure-task.md`

The test infrastructure bootstrap must include:
- Test project folder layout (`e2e/` directory structure)
- Mock/stub service definitions for each external dependency
- `docker-compose.test.yml` structure from environment.md
- Test runner configuration (framework, plugins, fixtures)
- Test data fixture setup from test-data.md seed data sets
- Test reporting configuration (format, output path)
- Data isolation strategy

**Self-verification**:
- [ ] Every external dependency from environment.md has a mock service defined
- [ ] Docker Compose structure covers all services from environment.md
- [ ] Test data fixtures cover all seed data sets from test-data.md
- [ ] Test runner configuration matches the consumer app tech stack from environment.md
- [ ] Data isolation strategy is defined

**Save action**: Write `01_test_infrastructure.md` (temporary numeric name)

**Jira action**: Create a Jira ticket for this task under the "Blackbox Tests" epic. Write the Jira ticket ID and Epic ID back into the task header.

**Rename action**: Rename the file from `01_test_infrastructure.md` to `[JIRA-ID]_test_infrastructure.md`. Update the **Task** field inside the file to match the new filename.

**BLOCKING**: Present test infrastructure plan summary to user. Do NOT proceed until user confirms.

---

### Step 1: Bootstrap Structure Plan (default mode only)

**Role**: Professional software architect
**Goal**: Produce `01_initial_structure.md` — the first task describing the project skeleton
**Constraints**: This is a plan document, not code. The `/implement` skill executes it.

1. Read architecture.md, all component specs, system-flows.md, data_model.md, and `deployment/` from DOCUMENT_DIR
2. Read problem, solution, and restrictions from `_docs/00_problem/` and `_docs/01_solution/`
3. Research best implementation patterns for the identified tech stack
4. Document the structure plan using `templates/initial-structure-task.md`

The bootstrap structure plan must include:
- Project folder layout with all component directories
- Shared models, interfaces, and DTOs
- Dockerfile per component (multi-stage, non-root, health checks, pinned base images)
- `docker-compose.yml` for local development (all components + database + dependencies)
- `docker-compose.test.yml` for blackbox test environment (blackbox test runner)
- `.dockerignore`
- CI/CD pipeline file (`.github/workflows/ci.yml` or `azure-pipelines.yml`) with stages from `deployment/ci_cd_pipeline.md`
- Database migration setup and initial seed data scripts
- Observability configuration: structured logging setup, health check endpoints (`/health/live`, `/health/ready`), metrics endpoint (`/metrics`)
- Environment variable documentation (`.env.example`)
- Test structure with unit and blackbox test locations

**Self-verification**:
- [ ] All components have corresponding folders in the layout
- [ ] All inter-component interfaces have DTOs defined
- [ ] Dockerfile defined for each component
- [ ] `docker-compose.yml` covers all components and dependencies
- [ ] `docker-compose.test.yml` enables blackbox testing
- [ ] CI/CD pipeline file defined with lint, test, security, build, deploy stages
- [ ] Database migration setup included
- [ ] Health check endpoints specified for each service
- [ ] Structured logging configuration included
- [ ] `.env.example` with all required environment variables
- [ ] Environment strategy covers dev, staging, production
- [ ] Test structure includes unit and blackbox test locations

**Save action**: Write `01_initial_structure.md` (temporary numeric name)

**Jira action**: Create a Jira ticket for this task under the "Bootstrap & Initial Structure" epic. Write the Jira ticket ID and Epic ID back into the task header.

**Rename action**: Rename the file from `01_initial_structure.md` to `[JIRA-ID]_initial_structure.md` (e.g., `AZ-42_initial_structure.md`). Update the **Task** field inside the file to match the new filename.

**BLOCKING**: Present structure plan summary to user. Do NOT proceed until user confirms.

---

### Step 2: Task Decomposition (default and single component modes)

**Role**: Professional software architect
**Goal**: Decompose each component into atomic, implementable task specs — numbered sequentially starting from 02
**Constraints**: Behavioral specs only — describe what, not how. No implementation code.

**Numbering**: Tasks are numbered sequentially across all components in dependency order. Start from 02 (01 is initial_structure). In single component mode, start from the next available number in TASKS_DIR.

**Component ordering**: Process components in dependency order — foundational components first (shared models, database), then components that depend on them.

For each component (or the single provided component):

1. Read the component's `description.md` and `tests.md` (if available)
2. Decompose into atomic tasks; create only 1 task if the component is simple or atomic
3. Split into multiple tasks only when it is necessary and would be easier to implement
4. Do not create tasks for other components — only tasks for the current component
5. Each task should be atomic, containing 0 APIs or a list of semantically connected APIs
6. Write each task spec using `templates/task.md`
7. Estimate complexity per task (1, 2, 3, 5 points); no task should exceed 5 points — split if it does
8. Note task dependencies (referencing Jira IDs of already-created dependency tasks, e.g., `AZ-42_initial_structure`)
9. **Immediately after writing each task file**: create a Jira ticket, link it to the component's epic, write the Jira ticket ID and Epic ID back into the task header, then rename the file from `[##]_[short_name].md` to `[JIRA-ID]_[short_name].md`.

**Self-verification** (per component):
- [ ] Every task is atomic (single concern)
- [ ] No task exceeds 5 complexity points
- [ ] Task dependencies reference correct Jira IDs
- [ ] Tasks cover all interfaces defined in the component spec
- [ ] No tasks duplicate work from other components
- [ ] Every task has a Jira ticket linked to the correct epic

**Save action**: Write each `[##]_[short_name].md` (temporary numeric name), create Jira ticket inline, then rename the file to `[JIRA-ID]_[short_name].md`. Update the **Task** field inside the file to match the new filename. Update **Dependencies** references in the file to use Jira IDs of the dependency tasks.

---

### Step 3: Blackbox Test Task Decomposition (default and tests-only modes)

**Role**: Professional Quality Assurance Engineer
**Goal**: Decompose blackbox test specs into atomic, implementable task specs
**Constraints**: Behavioral specs only — describe what, not how. No test code.

**Numbering**:
- In default mode: continue sequential numbering from where Step 2 left off.
- In tests-only mode: start from 02 (01 is the test infrastructure bootstrap from Step 1t).

1. Read all test specs from `DOCUMENT_DIR/tests/` (`blackbox-tests.md`, `performance-tests.md`, `resilience-tests.md`, `security-tests.md`, `resource-limit-tests.md`)
2. Group related test scenarios into atomic tasks (e.g., one task per test category or per component under test)
3. Each task should reference the specific test scenarios it implements and the environment/test-data specs
4. Dependencies:
   - In default mode: blackbox test tasks depend on the component implementation tasks they exercise
   - In tests-only mode: blackbox test tasks depend on the test infrastructure bootstrap task (Step 1t)
5. Write each task spec using `templates/task.md`
6. Estimate complexity per task (1, 2, 3, 5 points); no task should exceed 5 points — split if it does
7. Note task dependencies (referencing Jira IDs of already-created dependency tasks)
8. **Immediately after writing each task file**: create a Jira ticket under the "Blackbox Tests" epic, write the Jira ticket ID and Epic ID back into the task header, then rename the file from `[##]_[short_name].md` to `[JIRA-ID]_[short_name].md`.

**Self-verification**:
- [ ] Every scenario from `tests/blackbox-tests.md` is covered by a task
- [ ] Every scenario from `tests/performance-tests.md`, `tests/resilience-tests.md`, `tests/security-tests.md`, and `tests/resource-limit-tests.md` is covered by a task
- [ ] No task exceeds 5 complexity points
- [ ] Dependencies correctly reference the dependency tasks (component tasks in default mode, test infrastructure in tests-only mode)
- [ ] Every task has a Jira ticket linked to the "Blackbox Tests" epic

**Save action**: Write each `[##]_[short_name].md` (temporary numeric name), create Jira ticket inline, then rename to `[JIRA-ID]_[short_name].md`.

---

### Step 4: Cross-Task Verification (default and tests-only modes)

**Role**: Professional software architect and analyst
**Goal**: Verify task consistency and produce `_dependencies_table.md`
**Constraints**: Review step — fix gaps found, do not add new tasks

1. Verify task dependencies across all tasks are consistent
2. Check no gaps:
   - In default mode: every interface in architecture.md has tasks covering it
   - In tests-only mode: every test scenario in `traceability-matrix.md` is covered by a task
3. Check no overlaps: tasks don't duplicate work
4. Check no circular dependencies in the task graph
5. Produce `_dependencies_table.md` using `templates/dependencies-table.md`

**Self-verification**:

Default mode:
- [ ] Every architecture interface is covered by at least one task
- [ ] No circular dependencies in the task graph
- [ ] Cross-component dependencies are explicitly noted in affected task specs
- [ ] `_dependencies_table.md` contains every task with correct dependencies

Tests-only mode:
- [ ] Every test scenario from traceability-matrix.md "Covered" entries has a corresponding task
- [ ] No circular dependencies in the task graph
- [ ] Test task dependencies reference the test infrastructure bootstrap
- [ ] `_dependencies_table.md` contains every task with correct dependencies

**Save action**: Write `_dependencies_table.md`

**BLOCKING**: Present dependency summary to user. Do NOT proceed until user confirms.

---

## Common Mistakes

- **Coding during decomposition**: this workflow produces specs, never code
- **Over-splitting**: don't create many tasks if the component is simple — 1 task is fine
- **Tasks exceeding 5 points**: split them; no task should be too complex for a single implementer
- **Cross-component tasks**: each task belongs to exactly one component
- **Skipping BLOCKING gates**: never proceed past a BLOCKING marker without user confirmation
- **Creating git branches**: branch creation is an implementation concern, not a decomposition one
- **Creating component subdirectories**: all tasks go flat in TASKS_DIR
- **Forgetting Jira**: every task must have a Jira ticket created inline — do not defer to a separate step
- **Forgetting to rename**: after Jira ticket creation, always rename the file from numeric prefix to Jira ID prefix

## Escalation Rules

| Situation | Action |
|-----------|--------|
| Ambiguous component boundaries | ASK user |
| Task complexity exceeds 5 points after splitting | ASK user |
| Missing component specs in DOCUMENT_DIR | ASK user |
| Cross-component dependency conflict | ASK user |
| Jira epic not found for a component | ASK user for Epic ID |
| Task naming | PROCEED, confirm at next BLOCKING gate |

## Methodology Quick Reference

```
┌────────────────────────────────────────────────────────────────┐
│          Task Decomposition (Multi-Mode)                        │
├────────────────────────────────────────────────────────────────┤
│ CONTEXT: Resolve mode (default / single component / tests-only)│
│                                                                │
│ DEFAULT MODE:                                                   │
│  1.  Bootstrap Structure  → [JIRA-ID]_initial_structure.md     │
│      [BLOCKING: user confirms structure]                       │
│  2.  Component Tasks      → [JIRA-ID]_[short_name].md each    │
│  3.  Blackbox Tests       → [JIRA-ID]_[short_name].md each    │
│  4.  Cross-Verification   → _dependencies_table.md            │
│      [BLOCKING: user confirms dependencies]                    │
│                                                                │
│ TESTS-ONLY MODE:                                                │
│  1t. Test Infrastructure  → [JIRA-ID]_test_infrastructure.md   │
│      [BLOCKING: user confirms test scaffold]                   │
│  3.  Blackbox Tests       → [JIRA-ID]_[short_name].md each    │
│  4.  Cross-Verification   → _dependencies_table.md            │
│      [BLOCKING: user confirms dependencies]                    │
│                                                                │
│ SINGLE COMPONENT MODE:                                          │
│  2.  Component Tasks      → [JIRA-ID]_[short_name].md each    │
├────────────────────────────────────────────────────────────────┤
│ Principles: Atomic tasks · Behavioral specs · Flat structure   │
│   Jira inline · Rename to Jira ID · Save now · Ask don't assume│
└────────────────────────────────────────────────────────────────┘
```
