dependency-mapping

name	dependency-mapping
description	Map slice dependencies using DSM matrix and prioritize by risk

Dependency Mapping Skill

Map dependencies between implementation slices using Design Structure Matrix (DSM), calculate risk scores, and recommend implementation sequence.

When to Use

• During Ask mode Phase 2 (CONVERGE)
• When planning multi-slice features
• Before phasing to understand risk order

Instructions

Phase 1: Build DSM Matrix

Create a square matrix with slices on both axes. Mark dependencies with *:

         | #1.1 | #1.2 | #2.1 | #2.2 | #2.3 | #3.1 |
---------+------+------+------+------+------+------+
#1.1     |  -   |      |      |      |      |      |
#1.2     |  *   |  -   |      |      |      |      |
#2.1     |      |  *   |  -   |      |      |      |
#2.2     |      |      |  *   |  -   |      |  *   |
#2.3     |      |  *   |  *   |      |  -   |      |
#3.1     |      |      |      |      |      |  -   |

Legend: * = row depends on column
Reading: Row #2.2 has * in columns #2.1 and #3.1 = #2.2 depends on #2.1 AND #3.1

Phase 2: Calculate Dependency Score

For each slice, count:

Metric	Formula	Meaning
Fan-in	How many slices depend ON this?	High = blocker, ship early
Fan-out	How many slices does this DEPEND on?	High = risky, ship later
Dependency Score	Fan-out count	Lower = safer

Phase 3: Calculate Leverage Score

Score each slice on reuse of existing patterns:

Level	Score	Description
Full Reuse	0	Uses existing component from design system/Storybook as-is
Extend	1	Extends existing component with new props/variants
Compose	2	Composes multiple existing components
New Pattern	3	Creates new component following design system tokens
New System	5	Requires new patterns not in design system

Check these sources before scoring:

• /docs/design-system/components.md - Existing components
• Glob **/*.stories.tsx - Storybook patterns
• SemanticSearch for similar implementations in codebase

Phase 4: Calculate Risk Score

Risk Score = (Dependencies x 2) + Leverage + PriorityTier

Where PriorityTier:
- P1 (Frontend-only) = 0
- P2 (Frontend + Backend non-breaking) = 1
- P3 (Backend contract changes) = 2
- P4 (Data model changes) = 3

Phase 5: Identify Blockers

Flag slices that block others (high fan-in):

#3.1 WorkspaceInvite Entity
  Fan-in: 3 (blocks #2.2, #2.3, #2.4)
  RECOMMENDATION: Consider stub/mock for Phase 1, or ship early despite risk

Phase 6: Rank by Risk

Sort slices by Risk Score (lowest first = ships first):

Rank	Slice	Deps	Leverage	Tier	Risk Score
1	#1.1 Workspace Switcher	0	Extend (1)	P1 (0)	1
2	#1.2 Members Page UI	1	Compose (2)	P1 (0)	4
3	#2.1 List Members API	1	N/A	P2 (1)	4

Output Format

## Dependency Analysis

### DSM Matrix

[Matrix as shown above]

### Risk Scoring

| Slice | Deps | Leverage | Tier | Risk | Rank |
|-------|------|----------|------|------|------|
| [Slice] | [N] | [Level (score)] | P[N] | [Score] | [#] |

### Blockers Identified

| Slice | Blocks | Fan-in | Recommendation |
|-------|--------|--------|----------------|
| [Slice] | [List] | [N] | [Stub/Ship early/etc] |

### Recommended Sequence

1. [Lowest risk slice] - [Why safe]
2. [Next slice] - [Dependencies satisfied by #1]
...

### Existing System Leverage

| Component | Source | Slices Using | LOC Saved |
|-----------|--------|--------------|-----------|
| [Component] | [design-system/Storybook] | [List] | ~[N] |

Invocation

Invoke manually with "use dependency-mapping skill" or follow Ask mode Phase 2 (CONVERGE) which references this skill.

Related Skills

• phasing - Uses risk scores to group into phases
• design-context - Identifies existing patterns to leverage
• gtm-alignment - May override risk-based order for GTM priority