feat(parcel): add Parcel transformer plugin

[JoshKappler]

Summary

• @generaltranslation/parcel-transformer package, split out of feat(examples): add Parcel SPA example #1948 under the new 1-2k line PR cap.
• Base: main; the Parcel SPA example stacks on top and depends on this package.

Testing

• Transformer unit tests ship in the diff. Nothing run locally; CI and Greptile review this PR.

Notes

• Changeset is patch.
• Lockfile regen let next move 16.2.11 to 16.2.12 (minimumReleaseAge window); rest of the churn is Parcel's own tree.
• README points at examples/parcel-spa, which lands in the stacked PR.
• No Linear issue yet.

Greptile Summary

This PR introduces @generaltranslation/parcel-transformer, a new Parcel 2 plugin that runs the General Translation compiler at build time. Since Parcel is not covered by unplugin, the package wraps the same @generaltranslation/compiler core used by the Vite, webpack, and Rollup adapters.

• Two-pass transform: Babel first lowers TSX/JSX to the automatic JSX runtime (preserving ES module imports), then the GT compiler injects _hash values into <T> elements and t() calls — matching the behavior of the other bundler adapters exactly.
• Pre-gate efficiency: A cheap regex (GT_SIGNAL_RE) skips the Babel lowering pass for files with no GT usage. The <T[\\s>\\/] boundary (addressed in prior review) correctly avoids false positives for <Typography>, <Table>, etc.
• Config lifecycle: gt.config.json is loaded via config.getConfig so Parcel registers it as a dependency and invalidates transformed assets on change; the resolved plugin is memoized per options signature to avoid redundant disk reads across files.

Confidence Score: 5/5

Safe to merge — this is a self-contained new package with no changes to existing code paths.

The transformer is a new, isolated package. The two-pass Babel+GT flow is well-guarded: the pre-gate regex skips inert files cheaply, Babel failures are caught and passed through, and the GT compiler returning null correctly leaves the original source untouched for Parcel's default pipeline. The prior false-positive concern about the <T regex boundary has been fixed and is covered by tests.

Files Needing Attention: No files require special attention.

Important Files Changed

Filename	Overview
packages/parcel-transformer/src/index.ts	Core transformer: two-pass Babel+GT transform with pre-gate regex, config caching, and correct passthrough when GT compiler returns null.
packages/parcel-transformer/src/tests/transform.test.ts	Comprehensive tests covering JSX lowering, hash injection, cross-adapter parity, decorator handling, pre-gate signal matching with false-positive cases, and Parcel default export shape.
packages/parcel-transformer/package.json	Well-formed package manifest with correct ESM-only exports, Parcel engine constraint, and all required Babel peer dependencies declared.
packages/parcel-transformer/tsdown.config.mts	ESM-only build config; source maps intentionally omitted with documented rationale.
packages/parcel-transformer/tsconfig.json	Standard tsconfig extending the repo base; test files correctly excluded from type-checking compilation.
packages/parcel-transformer/vitest.config.ts	Minimal vitest config targeting Node environment, consistent with other packages in the monorepo.
.changeset/add-parcel-transformer.md	Patch changeset for a new package at 0.0.0; appropriate for an initial release.

_{Reviews (3): Last reviewed commit: "chore: trim comments to the 3-line house..." | Re-trigger Greptile}

[github-actions]

size-limit report 📦

Path	Size
generaltranslation	18.03 KB (0%)
generaltranslation/runtime	14.93 KB (0%)
generaltranslation/id	2.55 KB (0%)
generaltranslation/internal	7.38 KB (0%)
generaltranslation/types	89 B (0%)
generaltranslation/errors	81 B (0%)
@generaltranslation/format	9.5 KB (0%)
@generaltranslation/format/types	89 B (0%)
@generaltranslation/format/internal	880 B (0%)
gt-i18n	11.91 KB (0%)
gt-i18n/types	13 B (0%)
gt-i18n/internal	22.46 KB (0%)
gt-i18n/internal/types	13 B (0%)
@generaltranslation/react-core/pure	25.59 KB (0%)
@generaltranslation/react-core/hooks	20.61 KB (0%)
@generaltranslation/react-core/components	22.81 KB (0%)
@generaltranslation/react-core/components-rsc	26.16 KB (0%)
gt-react (client)	32.02 KB (0%)
gt-react (rsc)	28.67 KB (0%)
gt-react (server)	31.65 KB (0%)
gt-react/macros	8.86 KB (0%)
gt-next (client)	43.74 KB (0%)
gt-next (rsc)	47.52 KB (0%)
gt-next (server)	43.69 KB (0%)
gt-next/config	269.75 KB (0%)
gt-next/server	46.06 KB (0%)
gt-next/middleware	36.39 KB (0%)
gt-next/link	42.59 KB (0%)
gt-next/internal/_dictionary	144 B (0%)
gt-next/internal/_load-translations	144 B (0%)
gt-next/internal/_load-dictionary	144 B (0%)
gt-next/internal/_getLocale	125 B (0%)
gt-next/internal/_getRegion	122 B (0%)
gt-node	23.54 KB (0%)
gt-node/types	219 B (0%)
gt-node/internal	13.47 KB (0%)
gt-tanstack-start (client)	31.58 KB (0%)
gt-tanstack-start (server)	32.06 KB (0%)
gt-tanstack-start/server	10.27 KB (0%)
gt-react-native	30.05 KB (0%)
gt-react-native/plugin	4.62 KB (0%)
gt-react-native/internal	746 B (0%)

[JoshKappler]

@greptileai review

[JoshKappler]

@greptileai review

[JoshKappler]

@greptileai review