/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