Add guidance for vertical vs horizontal slicing in issue planning #31

New Issue

HugoNijhuis · 2026-01-04T11:57:41Z

HugoNijhuis commented

2026-01-04 11:57:41 +00:00

Context

During Arcadia issue planning, initial proposals were horizontal/technical slices (ADL syntax, then runtime, then UI) instead of vertical user-value slices.

Problem / Observation

The roadmap-planning and issue-writing skills don't explicitly guide toward vertical slices. This leads to issues like 'Add query syntax to ADL' instead of 'Domain expert can list all orders'.

Suggested Improvement

Add explicit guidance:

## Vertical vs Horizontal Slices

**Prefer vertical slices** - each issue delivers user-visible value:
- Good: 'User can save and reload their diagram'
- Bad: 'Add persistence layer' + 'Add save API' + 'Add load API'

**Test**: Can a user demo/test this issue independently?
- If yes → good vertical slice
- If no → probably a horizontal slice, break differently

**Break down by user capability, not technical layer.**

Affected Files

skills/roadmap-planning/SKILL.md
skills/issue-writing/SKILL.md

## Context During Arcadia issue planning, initial proposals were horizontal/technical slices (ADL syntax, then runtime, then UI) instead of vertical user-value slices. ## Problem / Observation The roadmap-planning and issue-writing skills don't explicitly guide toward vertical slices. This leads to issues like 'Add query syntax to ADL' instead of 'Domain expert can list all orders'. ## Suggested Improvement Add explicit guidance: ```markdown ## Vertical vs Horizontal Slices **Prefer vertical slices** - each issue delivers user-visible value: - Good: 'User can save and reload their diagram' - Bad: 'Add persistence layer' + 'Add save API' + 'Add load API' **Test**: Can a user demo/test this issue independently? - If yes → good vertical slice - If no → probably a horizontal slice, break differently **Break down by user capability, not technical layer.** ``` ## Affected Files - skills/roadmap-planning/SKILL.md - skills/issue-writing/SKILL.md

HugoNijhuis added this to the Ensure consistent quality milestone 2026-01-04 11:57:41 +00:00

HugoNijhuis referenced this issue from a commit

2026-01-09 12:21:59 +00:00

Add vertical vs horizontal slicing guidance

HugoNijhuis referenced a pull request that will close this issue

2026-01-09 12:22:09 +00:00

[Issue #31] Add guidance for vertical vs horizontal slicing #55

HugoNijhuis referenced a pull request that will close this issue

2026-01-09 12:23:11 +00:00

[Issue #31] Add guidance for vertical vs horizontal slicing #55

HugoNijhuis closed this issue

2026-01-09 12:23:17 +00:00