Upgrade TypeScript to 7 (build failing — needs review)

[woksin]

Summary

Upgrades Fundamentals to TypeScript 7.0.2 (the native compiler). The pure typecheck/compile path (tsc -b) works cleanly with TS7, but two third-party tools in the build/lint pipeline are not yet compatible with the TS7 native package, so the full CI (yarn ci) and publish (yarn build) currently fail. Opening for review — see Blockers below.

Package changes (old → new)

Package	Field	Old	New
root package.json	devDependencies.typescript	6.0.3	7.0.2
root package.json	packageManager	yarn@4.5.3	yarn@4.17.1
.yarnrc.yml	yarnPath	yarn-4.5.3.cjs	yarn-4.17.1.cjs

Source/ESLintConfig/package.json declares typescript only as a peerDependency (>=4.8.4) — left unchanged, as instructed (don't force consumers). No @types/* touched.

Why Yarn was bumped

Installing typescript@7.0.2 with Yarn 4.5.3 fails outright: Yarn's builtin TypeScript compat patch has a catch-all hunk gated >=5.7.1-rc (no upper bound) that renames lib/_tsc.js — a file the native compiler no longer ships — causing ENOENT during the fetch step. Yarn 4.17.1 is the first release that caps this range at >=5.7.1-rc <7.0.0-0, making the patch a no-op for TS7 so install succeeds. This bump is a hard prerequisite for the version bump, not optional.

Package manager

Yarn (workspaces, nodeLinker: node-modules). yarn install succeeds on 4.17.1. yarn.lock is gitignored in this repo, so it is not part of the diff.

Verification

• yarn install (Yarn 4.17.1): success.
• tsc --version resolves to 7.0.2; ts.version === "7.0.2".
• tsc -b on @cratis/fundamentals (Source/JavaScript): passes — exit 0, 31 .js + 31 .d.ts emitted. TS7 typechecking/compilation is clean.
• yarn ci / yarn build: fail at the lint and bundle steps (see Blockers).

Blockers (build failing — needs review)

The TS7 native typescript npm package is currently a thin wrapper over the Go binary and does not expose the full programmatic compiler API — ts.Extension, ts.ModuleKind, createDocumentRegistry, etc. are undefined. Tools that consume those internals break:

1. Lint — @typescript-eslint/typescript-estree@8.62.0 throws TypeError: Cannot read properties of undefined (reading 'Cjs') (reads ts.Extension.Cjs). typescript-eslint 8.x officially supports typescript <6.1.0; no TS7-compatible release exists yet.
2. Bundle — rollup-plugin-typescript2@0.37.0 (already the latest) throws TypeError: tsModule.createDocumentRegistry is not a function. The plugin uses the TS LanguageService API, absent from the native package.

Neither is fixable by a version bump today; both need upstream TS7 support (or a switch to different lint/bundle tooling), which is out of scope for a version bump. The typescript@7.0.2 + Yarn 4.17.1 changes are kept so the work is ready to land once the ecosystem catches up.

Workflow changes

None. .github/workflows/ was grepped for explicit typescript version pins and tsc install steps — there are none (workflows only pin NODE_VERSION and call yarn ci / yarn build). No workflow edits required.

🤖 Generated with Claude Code