# deprecation-and-migration

Skill · `skill:deprecation-and-migration`

Favz census, built 2026-09-27. Tool names and counts only. No repo names. HTML page: https://favz.co/tools/skill-deprecation-and-migration.html

- Repos that have it now: 21
- Repos that ever had it: 22
- Still have it: 95%
- Share of census repos with any tool: 0.07%

## Repos with it, by month

From commit dates in each repo's history. The last few days always look low, because repos found later fill them in.

| Month | Repos at month end |
|---|---|
| 2026-04 | 1 |
| 2026-05 | 6 |
| 2026-06 | 11 |
| 2026-07 | 15 |
| 2026-08 | 17 |
| 2026-09 | 21 |

## Goes with

Tools found in the same repos, ranked by lift: 3× means the two show up together three times as often as chance would give. Only pairs sharing 5 or more repos.

| Tool | Kind | Repos with both | Lift |
|---|---|---|---|
| [source-driven-development](https://favz.co/tools/skill-source-driven-development.md) | Skill | 19 | 1248.2× |
| [api-and-interface-design](https://favz.co/tools/skill-api-and-interface-design.md) | Skill | 18 | 1236.2× |
| [debugging-and-error-recovery](https://favz.co/tools/skill-debugging-and-error-recovery.md) | Skill | 18 | 1133.2× |
| [frontend-ui-engineering](https://favz.co/tools/skill-frontend-ui-engineering.md) | Skill | 19 | 1104.2× |
| [security-and-hardening](https://favz.co/tools/skill-security-and-hardening.md) | Skill | 18 | 1087.9× |
| [documentation-and-adrs](https://favz.co/tools/skill-documentation-and-adrs.md) | Skill | 17 | 1070.3× |
| [planning-and-task-breakdown](https://favz.co/tools/skill-planning-and-task-breakdown.md) | Skill | 16 | 967.0× |
| [spec-driven-development](https://favz.co/tools/skill-spec-driven-development.md) | Skill | 15 | 809.4× |
| [incremental-implementation](https://favz.co/tools/skill-incremental-implementation.md) | Skill | 16 | 755.5× |
| [code-review-and-quality](https://favz.co/tools/skill-code-review-and-quality.md) | Skill | 13 | 727.5× |
| [performance-optimization](https://favz.co/tools/skill-performance-optimization.md) | Skill | 19 | 683.5× |
| [context-engineering](https://favz.co/tools/skill-context-engineering.md) | Skill | 18 | 543.9× |

## Comes in the same pack

1 tools almost never appear without this one. Most likely people copy them in together.

- [browser-testing-with-devtools](https://favz.co/tools/skill-browser-testing-with-devtools.md)