Sample
Differentiate compilerOptions.moduleResolution modes, module-inferred defaults, extensionless imports, and package exports encapsulation in TypeScript 5.9.3
sha256:754cc486559403bcea3329fe1832412e8eaa4798adc2a50df46d57de54a703b1
PUBLISHED
L3_CONTRACT_PASS
MIT-0
Execution evidence
Declared environment and signed verification runs are separated so you can see exactly what this sample proves.
Evidence basisSigned contract pass
Verification receipts1
Verification levelL3_CONTRACT_PASS
Declared environment
- Execution context
- node
- Operating system
- linux
- Architecture
- x64
- Runtime
- node
- Language
- node
- Package manager
- npm
Verification-run environments
- Execution context
- node 22
- Operating system
- linux alpine · musl
- Architecture
- x64
- Runtime
- node 22
- Language
- javascript
- Package manager
- npm
- Execution
- container · docker
CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · node-typescript@1 · 2026-08-17
Case
- Goal
- Differentiate compilerOptions.moduleResolution modes, module-inferred defaults, extensionless imports, and package exports encapsulation in TypeScript 5.9.3 HOW
- Packages
-
typescript 5.9.3
- Environment
- node
- Created
- 2026-08-17T09:28:39Z
Commonly assumed
Setting compilerOptions.module to ESNext automatically enables modern Node or Bundler module resolution to resolve node_modules packages.
The sample's author recorded this as what a developer or model would expect here. The contract below is what actually ran.
Contract
- When compilerOptions.moduleResolution is omitted, compilerOptions.module set to ESNext defaults moduleResolution to Classic (1) rather than Node or Bundler, while Preserve defaults to Bundler (100) and Node16 defaults to Node16 (3).
- compilerOptions.moduleResolution set to Bundler accepts extensionless relative imports and directory index imports in ESM contexts
- compilerOptions.moduleResolution set to Node16 and NodeNext rejects extensionless relative imports with TS2835 and directory imports with TS2834
- relative .js specifiers resolve to underlying .ts source files across Node16, NodeNext, and Bundler moduleResolution modes
- direct .ts extension imports require allowImportingTsExtensions and otherwise fail with TS5097
- Node16 moduleResolution selects import or require package export conditions based on importer format, whereas Bundler defaults to import
- Node16, NodeNext, and Bundler moduleResolution enforce package exports encapsulation with TS2307, whereas legacy Node10 ignores exports maps
- Bundler moduleResolution respects customConditions compiler option to resolve matching conditional package exports
Files
- NOTES.md
- csx.json
- package-lock.json
- package.json
- src/index.mjs
- test/contract.mjs
Download the source artifact (tar.gz)
Origin Seeder
csx-seed
Verification receipts
- node 22 · linux alpine/x64 · docker · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · node-typescript@1 · 2026-08-17 · ed25519:d91480838ac982c9