chore(esm): Convert the structure package to ESM only

[Tobbe]

This was the last package that still used Babel for building

[netlify]

✅ Deploy Preview for cedarjs canceled.

Name	Link
🔨 Latest commit	03f07d3
🔍 Latest deploy log	https://app.netlify.com/projects/cedarjs/deploys/69b9d450c49696000862ab0b

[nx-cloud]

🤖 Nx Cloud AI Fix

Ensure the fix-ci command is configured to always run in your CI pipeline to get automatic fixes in future runs. For more information, please see https://nx.dev/ci/features/self-healing-ci

---

View your CI Pipeline Execution ↗ for commit 03f07d3

Command	Status	Duration	Result
nx run-many -t build:pack --exclude create-ceda...	✅ Succeeded	8s	View ↗
nx run-many -t build	✅ Succeeded	7s	View ↗
nx run-many -t test --minWorkers=1 --maxWorkers=4	✅ Succeeded	5s	View ↗
nx run-many -t test:types	✅ Succeeded	10s	View ↗

---

☁️ Nx Cloud last updated this comment at 2026-03-17 22:45:36 UTC

[greptile-apps]

Greptile Summary

This PR completes the ESM migration of the @cedarjs/structure package — the last package in the monorepo still using Babel for its build. It switches to pure TypeScript compilation (tsc), adds "type": "module" to package.json, adds .js extensions to all relative imports, and replaces the two decorator dependencies (lazy-get-decorator and lodash-decorators) with lightweight inline implementations.

Key changes worth noting:

• Custom lazy/memo decorators replace external libraries. The lazy implementation is functionally equivalent for runtime use but is missing configurable: true on the cached own property (a subtle divergence from the original library that may affect test spies).
• createRequire workaround is used to load @prisma/internals, which is a CJS-only bundle incompatible with Node's ESM static named-export analysis — this is the correct approach and is well-documented with a comment.
• Babel enum workaround removed in check.ts: DiagnosticSeverity no longer needs to be imported via .default, so both symbols are now cleanly destructured in a single import.
• tsconfig.json overrides emitDeclarationOnly: false from the base config so TypeScript emits both JS and .d.ts files — the correct setup when Babel is no longer in the pipeline.
• package.json exports expose several internal ./dist/model/* sub-paths, which couples the public API to the internal build directory structure.

Confidence Score: 4/5

• Safe to merge with minor follow-up items on the custom decorator implementation and package exports.
• The core ESM conversion (import extensions, tsconfig, package.json type:module) is mechanically straightforward and correct. The CJS interop for @prisma/internals is handled well. The main concerns are: (1) the lazy decorator drops configurable: true from the original library which could break test spies, and (2) internal dist/ paths are exposed in the exports map. Neither is a runtime blocker for the primary use case, but the decorator difference is a subtle behavioural regression worth fixing before shipping.
• packages/structure/src/x/decorators.ts deserves the most attention — the custom lazy and memo implementations replace external libraries and the configurable regression could affect downstream test infrastructure.

Important Files Changed

Filename	Overview
packages/structure/src/x/decorators.ts	Replaces lazy-get-decorator and lodash-decorators with custom lazy and memo implementations. The lazy decorator is missing configurable: true on the cached property (regression from original library), and __memoCache is assigned as an enumerable own property.
packages/structure/package.json	Adds "type": "module", new exports map, removes Babel/lodash-decorators/lazy-get-decorator dependencies. The exports map exposes internal ./dist/ paths directly, tying the public API to the build output directory.
packages/structure/tsconfig.json	Switches from declaration-only emit (Babel did JS) to full emit. Uses module: "node20" with moduleResolution: "node16" which is a minor inconsistency; they should ideally be the same version.
packages/structure/src/model/RWProject.ts	Uses createRequire to load @prisma/internals (CJS-only bundle) reliably from ESM context. Constructor no longer takes projectRoot; getPaths() is called directly. Clean change with good code comment explaining the CJS workaround.
packages/structure/src/nodes.ts	Adds .js extensions to all relative imports. Updates @memo(JSON.stringify) to @memo((...args) => JSON.stringify(args)) — needed because the previous form passed JSON.stringify as a variadic callback directly, which incorrectly received arguments like (value, replacer, space) from the internal serializer call.
packages/cli/src/commands/check.ts	Removes the workaround for the Babel enum issue where DiagnosticSeverity had to be imported via .default. Now both printDiagnostics and DiagnosticSeverity are cleanly destructured from the same import.
packages/cli/src/telemetry/resource.js	Removes projectRoot: getPaths().base from new RWProject() — aligns with the updated constructor that reads paths directly via getPaths() internally.
packages/structure/src/model/RWSDL.ts	Migrates GraphQL imports from deep sub-paths (graphql/language/parser) to top-level graphql package, and updates import extensions to .js.
packages/structure/src/model/RWSDLField.ts	Migrates GraphQL type imports from deep sub-paths (graphql/language/ast) to top-level graphql package, and updates relative import extensions to .js.
packages/structure/.babelrc.js	Deleted — Babel configuration is no longer needed now that TypeScript handles the full build.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A["tsc -p tsconfig.json\n(module: node20, moduleResolution: node16)"]
    A --> B["dist/*.js\n(ESM output)"]
    A --> C["dist/*.d.ts\n(Type declarations)"]

    subgraph pkg ["@cedarjs/structure package.json"]
        E["exports: '.' → dist/index.js"]
        F["exports: './dist/model/RWProject'"]
        G["exports: './dist/model/RWRoute'"]
        H["exports: './dist/model/RWPage.js'"]
    end

    B --> pkg
    C --> pkg

    subgraph esm ["ESM Source (src/)"]
        I["index.ts\n(exports DiagnosticSeverity, RWProject, RWRoute)"]
        J["model/RWProject.ts\n(createRequire for @prisma/internals)"]
        K["x/decorators.ts\n(custom lazy + memo)"]
        L["model/*.ts\n(.js import extensions)"]
    end

    M["@prisma/internals\n(CJS-only)"] -->|createRequire| J
    K -->|"@lazy() getters"| L
    K -->|"@memo() methods"| L
    I --> J
    J --> L

Loading

_{Last reviewed commit: 1acc046}

[Tobbe]

@greptileai Please do a full review again