---
name: interdependent-change-planning
description: Use for changes that touch multiple related files, flows, or data paths and must be planned as one connected system.
---

# Interdependent Change Planning

## Quick Index (Action-Routed)
### Read First (All Actions)
1. `Mission`
2. `Trigger Rule`
3. `Connected-Change Standard`

### Action Modules (Read As Needed)
1. Mapping coupled surfaces:
   - `Impact Map`
   - `Dependency Ring`
2. Planning safe edits:
   - `Coherent Slice Rule`
   - `Shared-Invariant Check`
3. Finishing coherently:
   - `Validation and Handoff`

### Output
1. `Output Contract`

## Mission
Keep changes coherent across all parts that depend on one another.

## Trigger Rule
Use this skill when:
1. a change affects multiple related components, files, routes, or data paths
2. a local edit would leave adjacent behavior inconsistent
3. one update implies companion changes elsewhere
4. the user asks for a thoughtful or system-aware change

## Connected-Change Standard
Treat the touched area as a connected system, not isolated edits.

Before editing:
1. identify direct touchpoints
2. identify downstream consumers
3. identify shared invariants
4. decide whether companion updates are required

## Impact Map
Record:
1. primary file or module being changed
2. directly affected neighbors
3. dependent surfaces that must stay aligned
4. validation needed for the connected set

## Dependency Ring
For each touched element, check:
1. what reads it
2. what writes it
3. what assumes its shape or meaning
4. what breaks if it changes alone

## Coherent Slice Rule
Make the smallest change that is still system-complete.

Do not:
1. land half of a coupled update
2. leave temporary mismatches without a follow-up plan
3. change one surface while knowingly desynchronizing another

## Shared-Invariant Check
Before finalizing, confirm:
1. shared data shapes still match
2. user flows still line up
3. docs or tests that describe the same concept agree

## Validation and Handoff
Validate the connected surfaces together and note any deferred companion work explicitly.

## Output Contract
When using this skill, provide:
1. connected surfaces identified
2. invariants checked
3. coordinated updates made
4. deferred companion work, if any
5. validation summary

## Related Skills
- [Thoughtful Approach](../thoughtful-approach/SKILL.md): decide what should move together from a user-value perspective.
- [Regression Prevention](../regression-prevention/SKILL.md): protect dependent behavior while coordinating the change.
- [Order of Operations](../order-of-operations/SKILL.md): sequence foundational and dependent edits correctly.
- [File Structure Optimization](../file-structure-optimization/SKILL.md): use when coupling comes from repository layout.
- [Doc Maintenance](../doc-maintenance/SKILL.md): keep connected docs aligned with implementation.