Agent-Skills.md

Agent Skills: Convert an internal package to TypeScript

Convert a legacy internal Ghost workspace package from JavaScript or CommonJS to the repository's TypeScript and ESM golden path while preserving file history and runtime compatibility. Use when modernizing an existing or newly migrated private package, including staged lib-to-src moves, JS-to-TS renames, consumer analysis, and package or archive verification.

ID: tryghost/ghost/convert-internal-package-to-typescript

Repository

tryghost/ghost
TryGhostLicense: MIT
55,33111,970

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npx skills add tryghost/ghost --skill convert-internal-package-to-typescript

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Skill Metadata

Name
convert-internal-package-to-typescript
Description
Convert a legacy internal Ghost workspace package from JavaScript or CommonJS to the repository's TypeScript and ESM golden path while preserving file history and runtime compatibility. Use when modernizing an existing or newly migrated private package, including staged lib-to-src moves, JS-to-TS renames, consumer analysis, and package or archive verification.

Convert an internal package to TypeScript

Modernize an internal package without mixing mechanical moves with semantic changes or obscuring file history. Treat packages/README.md as the authority for the package's lifetime architecture; this skill owns only the conversion workflow.

Confirm this workflow applies

Read packages/README.md completely, then inspect the package, its consumers, and comparable current packages. Confirm that the package is internal-only and can adopt the documented single-build TypeScript and ESM contract.

Before editing:

  1. Find every import, require(), export, runtime asset and path reference.
  2. Inspect package metadata, build and test configuration, release/archive inclusion, and any dynamic module loading.
  3. Run the package's existing tests and representative consumer checks to establish a baseline.
  4. Identify supported consumers that cannot load the golden-path ESM output.

If the package has an active independent release or third-party support contract, or requires a format that conflicts with the golden path, stop and establish its support contract instead of applying this workflow mechanically. Deprecated historical npm versions do not by themselves block conversion.

Read references/history-and-verification.md completely before planning the commits.

Preserve lineage with three focused commits

Keep each commit independently valid and verify rename detection before moving on. Avoid formatting or opportunistic cleanup in the mechanical commits.

1. Move sources from lib to src

Use git mv to move the source tree. Update only references that must change for the new path, such as test imports, build inputs and package metadata. Do not change module syntax, file extensions or implementation in this commit.

Use the subject Moved <package> sources from lib to src when that accurately describes the change.

2. Change file extensions to TypeScript

Use git mv for .js to .ts renames. Add only the minimum configuration and syntax adjustments needed for the renamed sources to parse and for this commit to remain coherent. Preserve behavior and defer meaningful typing and ESM conversion to the next commit.

Use the subject Changed <package> file extensions to TypeScript.

3. Convert the implementation to TypeScript and ESM

Apply the package contract from packages/README.md: shared config packages, minimal package-local config, ESM metadata and exports, standard scripts, and a single compiled output unless a verified consumer requires an exception. Replace the package's migration status with ghostPackage.goldenPath: compliant only after every mechanical golden-path check passes.

Use the subject Converted <package> to TypeScript.

Hold the conversion to production standards

  • Model real input, output and registry shapes; do not replace missing types with any.
  • Use unknown only at genuine untrusted boundaries and narrow it promptly.
  • Do not use broad casts, non-null assertions, @ts-ignore, or lint disables merely to silence the compiler.
  • Preserve the package's runtime API unless an API change is explicitly in scope and all consumers are updated.
  • Use explicit .ts extensions for relative TypeScript imports under the repository's NodeNext configuration.
  • Replace dynamic CommonJS discovery with explicit typed registries when ESM cannot express the old loading pattern safely.
  • Ensure JSON and other runtime assets are emitted and available from build/.
  • Avoid top-level await so supported CommonJS consumers can use Node's require(esm) interoperability.
  • Do not weaken shared TypeScript, ESLint or Vitest rules to make the conversion pass.

Verify the result

Run the build, tests and lint commands required by packages/README.md. Also:

  • exercise representative consumers using their real import or require() path;
  • test raw source resolution and compiled output where both are used;
  • inspect the packed package or Ghost release component when exports, runtime assets or archive inclusion changed;
  • run the repository build when the workspace build graph changed;
  • run git diff --summary for each mechanical commit and git log --follow on representative files to confirm the lineage remains readable.

The modernization PR may be rebase-merged when these commits are independently valid and intentionally ordered. This does not change the merge-commit requirement for a preceding subtree history import.

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