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Run npx skillmds@latest add lennetech/modernizing-toolchain in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

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Is Modernizing Toolchain free to use?

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Who published Modernizing Toolchain?

lenneTech (@lennetech) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Modernizing Toolchain by lennetech — Agent Skill

Name: Modernizing Toolchain
Rating: 4.666666666666667 (3 reviews)
Author: lenneTech

Modernizing Toolchain

Migrates lenne.tech projects from the legacy jest+eslint+prettier toolchain to the current vitest+oxlint+oxfmt baseline used by nest-server-starter and nuxt-base-starter. Covers swc decoratorMetadata config, the @Prop union-type fix, supertest default-import correction, the Nitro PORT-vs-NITRO_PORT bug, and the config.env.ts + check-envs.sh patterns. Activates when aligning a project with current starter conventions, and on Mongoose union-type errors or ERR_SOCKET_BAD_PORT crashes. NOT for dependency version bumps (use maintaining-npm-packages). NOT for nest-server major upgrades (use nest-server-updating).

lenneTech Updated Sep 10, 2026

File contents

Modernizing the lenne.tech Toolchain

When This Skill Activates

Migrating an existing API/App from jest → vitest, eslint → oxlint, prettier → oxfmt
Adopting the check / check:fix / check:envs pipeline used by the starters
Debugging Mongoose "Cannot determine a type for the X field (union/intersection/ambiguous type was used)" after switching to vitest+SWC
Debugging ERR_SOCKET_BAD_PORT from node .output/server/index.mjs in any check pipeline
Debugging missing or stale types.gen.ts after a Nuxt update
Aligning a project with the current config.env.ts shape (NSC__-only + fail-fast + helper functions)
Cleaning up phantom Unix-domain-sockets named [33m12345[39m in the project root

Reference Repositories (public)

All references in this skill are to the public lenne.tech repos. Never reference local clone paths in skill output:

API starter: https://github.com/lenneTech/nest-server-starter
API framework: https://github.com/lenneTech/nest-server
App starter: https://github.com/lenneTech/nuxt-base-starter
App framework: https://github.com/lenneTech/nuxt-extensions
Monorepo template: https://github.com/lenneTech/lt-monorepo
CLI: https://github.com/lenneTech/cli

The Migration Checklist (full pipeline)

Eleven phases in fixed order, each assuming the previous one landed. Every phase has a clear "done" signal — proceed only when it is met.

Phase	Subject
1	Inventory
2	API: jest to vitest
3	API: eslint to oxlint, prettier to oxfmt
4	App: jest/eslint/prettier to vitest/oxlint/oxfmt
5	`check` pipeline
6	`scripts/check-server-start.sh` (port-robust, ANSI-safe)
7	`config.env.ts`
8	`scripts/check-envs.sh` + `tests/fixtures/.env.deployed-test`
9	`main.ts`
10	GitLab CI
11	`docker-compose.yml`

Full commands, file contents and per-phase traps: reference/migration-checklist.md.

Done Signals

After all phases, both must be true:

<pm> run check from the monorepo root prints
```
Lerna (powered by Nx)   Successfully ran target check for 2 projects
```
with both api and app green (audit + format:check + lint + test + build + check-server-start).
<pm> run check:envs (api) prints All env configurations OK. (six envs across two phases).
No tests skipped, no warnings tolerated: pre-existing failures in either subproject must be fixed as part of the migration, not silenced. The check pipeline is intentionally strict — silencing it here defeats the purpose of bringing the project to the current baseline.

Skill Boundaries

User Intent	Correct Skill
"Migrate to vitest" / "switch to oxlint" / "modernize the toolchain"	THIS SKILL
"Bump nest-server to a newer minor"	`nest-server-updating`
"Update all packages" / "audit + fix"	`maintaining-npm-packages`
"Run my check pipeline" / "check failed"	`running-check-script` (this skill cross-references it)
"Build a new feature" / "add a service"	`generating-nest-servers` or `developing-lt-frontend`

Related Skills & Commands

Element	Relationship
`running-check-script` skill	Defers the `ERR_SOCKET_BAD_PORT` / ANSI-strip hazards to this skill's Phase 6
`maintaining-npm-packages` skill	Handles version bumps; this skill handles the toolchain switch itself
`nest-server-updating` skill	nest-server major upgrades, which often surface the same swc/decorator issues
`/lt-dev:fullstack:update-all`	Syncs the workspace-root toolchain from `lt-monorepo`
`/lt-dev:check`	Verifies the migrated toolchain actually runs green

---name: modernizing-toolchaindescription: Migrates lenne.tech projects from the legacy jest+eslint+prettier toolchain to the current vitest+oxlint+oxfmt baseline used by nest-server-starter and nuxt-base-starter. Covers swc decoratorMetadata config, the @Prop union-type fix, supertest default-import correction, the Nitro PORT-vs-NITRO_PORT bug, and the config.env.ts + check-envs.sh patterns. Activates when aligning a project with current starter conventions, and on Mongoose union-type errors or ERR_SOCKET_BAD_PORT crashes. NOT for dependency version bumps (use maintaining-npm-packages). NOT for nest-server major upgrades (use nest-server-updating).---# Modernizing the lenne.tech Toolchain## When This Skill Activates- Migrating an existing API/App from jest → vitest, eslint → oxlint, prettier → oxfmt- Adopting the `check` / `check:fix` / `check:envs` pipeline used by the starters- Debugging Mongoose `"Cannot determine a type for the X field (union/intersection/ambiguous type was used)"` after switching to vitest+SWC- Debugging `ERR_SOCKET_BAD_PORT` from `node .output/server/index.mjs` in any check pipeline- Debugging missing or stale `types.gen.ts` after a Nuxt update- Aligning a project with the current `config.env.ts` shape (NSC__-only + fail-fast + helper functions)- Cleaning up phantom Unix-domain-sockets named `[33m12345[39m` in the project root## Reference Repositories (public)All references in this skill are to the public lenne.tech repos. **Never reference local clone paths in skill output**:- API starter: <https://github.com/lenneTech/nest-server-starter>- API framework: <https://github.com/lenneTech/nest-server>- App starter: <https://github.com/lenneTech/nuxt-base-starter>- App framework: <https://github.com/lenneTech/nuxt-extensions>- Monorepo template: <https://github.com/lenneTech/lt-monorepo>- CLI: <https://github.com/lenneTech/cli>## The Migration Checklist (full pipeline)Eleven phases in fixed order, each assuming the previous one landed. Every phase has a clear "done" signal — proceed only when it is met.| Phase | Subject ||---|---|| 1 | Inventory || 2 | API: jest to vitest || 3 | API: eslint to oxlint, prettier to oxfmt || 4 | App: jest/eslint/prettier to vitest/oxlint/oxfmt || 5 | `check` pipeline || 6 | `scripts/check-server-start.sh` (port-robust, ANSI-safe) || 7 | `config.env.ts` || 8 | `scripts/check-envs.sh` + `tests/fixtures/.env.deployed-test` || 9 | `main.ts` || 10 | GitLab CI || 11 | `docker-compose.yml` |Full commands, file contents and per-phase traps: [`reference/migration-checklist.md`](reference/migration-checklist.md).## Done SignalsAfter all phases, both must be true:1. `<pm> run check` from the monorepo root prints ``` Lerna (powered by Nx) Successfully ran target check for 2 projects ``` with both api and app green (audit + format:check + lint + test + build + check-server-start).2. `<pm> run check:envs` (api) prints `All env configurations OK.` (six envs across two phases).3. **No tests skipped, no warnings tolerated**: pre-existing failures in either subproject must be fixed as part of the migration, not silenced. The `check` pipeline is intentionally strict — silencing it here defeats the purpose of bringing the project to the current baseline.## Skill Boundaries| User Intent | Correct Skill ||------------|---------------|| "Migrate to vitest" / "switch to oxlint" / "modernize the toolchain" | **THIS SKILL** || "Bump nest-server to a newer minor" | `nest-server-updating` || "Update all packages" / "audit + fix" | `maintaining-npm-packages` || "Run my check pipeline" / "check failed" | `running-check-script` (this skill cross-references it) || "Build a new feature" / "add a service" | `generating-nest-servers` or `developing-lt-frontend` |## Related Skills & Commands| Element | Relationship ||---------|--------------|| `running-check-script` skill | Defers the `ERR_SOCKET_BAD_PORT` / ANSI-strip hazards to this skill's Phase 6 || `maintaining-npm-packages` skill | Handles version bumps; this skill handles the toolchain switch itself || `nest-server-updating` skill | nest-server major upgrades, which often surface the same swc/decorator issues || `/lt-dev:fullstack:update-all` | Syncs the workspace-root toolchain from `lt-monorepo` || `/lt-dev:check` | Verifies the migrated toolchain actually runs green |

Frequently asked questions