Work Decomposition

This skill guides the process of breaking higher-level work into actionable lower-level items.

The Decomposition Chain

Vision: "Make X a better experience"
    ↓
Initiative: "Reduce page load time by 50%"
    ↓
Tasks: "Profile slow queries", "Add caching layer", "Optimize images"

Each level breaks work above it into concrete, actionable pieces at appropriate scope.

When to Decompose

Decompose ahead of capacity, not upfront:

• When team's current backlog is nearing its end
• During tail end of current work to prepare next batch
• When backlog is getting low (signal to look up and pull work down)

Avoid: Decomposing everything upfront (waterfall). Have work ready when capacity frees up, not entire project planned before starting.

The Decompose Phase

Initiatives have an explicit "decompose" phase:

discovery → design → ready → decompose → active → completed

Why Decompose is Explicit

The decompose phase creates a visible buffer:

• Solutions can pile up waiting to be broken into tasks
• Tracks how long things sit here
• Makes bottlenecks visible in multi-team environments

Don't skip to decompose early. Premature decomposition leads to tasks that solve wrong problems, rework when design changes, wasted effort.

Sizing by Scope, Not Time

Size by scope and impact, not implementation time:

Tasks: Atomic Units

• Scope: Discrete, completable piece with clear done criteria
• Impact: Moves the needle on parent initiative
• Independence: Can be worked without constant coordination
• Examples: "Add caching layer", "Write migration script", "Update API endpoint"

If a task has meaningful subtasks, it should probably be an initiative.

Initiatives: Capability Increments

• Scope: Creates fundamental increment in capability
• Impact: Meaningfully changes what system can do
• Coherence: Tasks within work toward unified outcome
• Examples: "User authentication", "Search functionality", "Billing integration"

If it doesn't change what system can do, it might just be a task.

Decomposition Patterns

Vertical Slices (Preferred)

Break by user-visible functionality:

Initiative: "User authentication"
├── Task: "Login flow"
├── Task: "Registration flow"
├── Task: "Password reset"
└── Task: "Session management"

Each task delivers something user can see/use.

Horizontal Layers (Use Sparingly)

Break by technical component:

Initiative: "User authentication"
├── Task: "Database schema"
├── Task: "API endpoints"
├── Task: "Frontend components"
└── Task: "Integration tests"

Creates dependencies between tasks. Prefer vertical slices.

Risk-First

Break by unknowns:

Initiative: "ML recommendation engine"
├── Task: "Spike: Evaluate model options" (high uncertainty)
├── Task: "Build training pipeline" (after spike)
└── Task: "Integration with product" (low uncertainty)

Address risky/uncertain work first to fail fast.

Milestone-Based

Break by deliverable checkpoints:

Initiative: "Platform migration"
├── Task: "Phase 1: Read path on new platform"
├── Task: "Phase 2: Write path on new platform"
├── Task: "Phase 3: Deprecate old platform"
└── Task: "Phase 4: Cleanup"

Each milestone independently valuable and deployable.

Naming Tasks Before They Exist

Decomposition is the single biggest source of invented shorthand: you draft five tasks in a message, call them "Task 1" through "Task 5", and those labels outlive the message.

While the tasks are still proposals, name them by full title in quotes and say they aren't created yet:

Proposed (not yet created): "Login flow", "Registration flow", "Password reset", "Session management".

Do not assign an interim ID — not T1, not "task A", not a placeholder short code to be swapped later. Numbers in a list are for the user to answer against in that message ("re: 3, split it"); they are not identifiers and don't survive into the next message, a document, or a commit.

The moment you call create_document, the tool result gives you the real short code. From then on the task's name is that short code, and the working title is just its title. Never predict what a short code will be — the counter is Metis's, not yours.

A slice is a shape, not a name. "Vertical slice" describes how the work was cut, the way "horizontal layer" and "risk-first" do. It is not an identifier. Labelling the cuts "Slice 1" through "Slice 5" while drafting, and then writing those labels into the initiative's Implementation Plan, leaves the plan referring to five entities that exist nowhere -- no short code, no phase, nothing that can be completed. A slice becomes a task; its name is that task's short code.

The same applies to sequencing. "Phase 1 tasks", "the first batch", "the DB workstream" are entities nothing in Metis holds; they die with the conversation while people keep referring to them. Express ordering as a dependency between short codes and record it in the initiative's implementation plan.

The implementation plan is written in short codes. Every item in it names a real task, or a quoted title for a task not yet created. Never write a short code into the plan that you have not just created or just read back -- a plan citing PROJ-T-0012 for a task that was never created is worse than a vague one, because it looks like it resolves.

See the metis-vocabulary skill for the full rules.

Quality Checklist

Good decomposition - each child item:

• Independently valuable: Delivers something useful alone
• Clearly scoped: Know when it's done
• Right-sized: Matches scope expectations for level
• Aligned to parent: Clearly contributes to level above
• Written in STE: Objective and acceptance criteria use ASD-STE100 Simplified Technical English. Each criterion is one imperative sentence of 20 words or fewer, with a verifiable result. See the ste100-writing skill.

Bad decomposition smells:

• Too granular: "write line 42" - steps, not tasks
• Too vague: "make it better" - no completion criteria
• Wrong level: Doesn't match document type scope
• Orphaned: Doesn't trace back to parent
• Overlapping: Multiple items covering same ground

Common Mistakes

Mistake	Problem	Fix
Decomposing too early	Tasks solve wrong problem	Stay in discovery/design until approach clear
Decomposing too late	Initiative active with no tasks	Decompose before moving to active
Wrong granularity	Tasks that are initiatives or vice versa	Apply scope heuristics
Missing alignment	Tasks don't contribute to initiative	Each task needs obvious connection to parent

Judgment Calls

• Uncertain scope? Create spike/research task first, then decompose based on findings
• Large initiative? Consider if it's really multiple capability increments
• Tiny initiative? Consider if it's really just a task
• Cross-cutting? May need tasks under multiple initiatives, or dedicated "platform" initiative

After Drafting Tasks

Once the tasks exist, run one bounded review over them as a set with the grill-decomposition skill (/grill-decomposition PROJ-I-0001). It checks slice boundaries, ordering, verifiable acceptance criteria, and scope leaks, and writes the answers into the task documents. Do this before the initiative moves to active. If the review keeps surfacing design questions, that is a signal to go back to grill-initiative, not to press on.

Additional Resources

For detailed decomposition patterns and examples:

• references/decomposition-patterns.md - Complete pattern catalog with examples