What microsoft/TypeScript shipped
Written by FoxPlug from public releases; not affiliated with Microsoft. An automatic summary of the public release, pull request and commit data of github.com/microsoft/TypeScript. Microsoft did not write it and does not use or endorse FoxPlug. Every line links to the public change it describes.
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Week of September 21, 2026
What shipped
- Build Orchestrator API implemented, providing async methods to build projects and manage references. Pull request #64158
- Standalone created source files now acquire from the global parse cache and return a disposable lease for better resource management. Pull request #64434
- Module resolution overrides added, allowing isolated arbitrary resolveModuleName calls and override mechanisms in API programs. Pull request #64299
- tsc -b now schedules projects by dependency depth to reduce builder idle time on upstream projects. Pull request #64220
- Incremental caching added to all codegen tasks, reducing time by up to 80% when cached results are reusable. Pull request #64331
- Never type now correctly treated as non-mutable-array-like when deciding readonly tuples. Pull request #64389
- Object property completions now respect quote preference for non-identifier property names. Pull request #64359
- Global diagnostic collection now matches Strada's approach and hides non-diagnostic global errors in the editor. Pull request #64452
- tsconfig plugins now parsed for external error reporting, and MappedType properties exposed. Pull request #64397
- Enum generator moved from Herebyfile into tools scripts for better organization. Pull request #64391
Why it matters
This week brings improvements to the API layer with new orchestration and module resolution capabilities, performance optimizations in build systems and codegen caching, and fixes to diagnostic handling and type narrowing. These changes make incremental builds faster, improve resource management in the public API, and fix edge cases in type checking.
Changelog entry
- Build Orchestrator API with async buildReferences, clean, and cleanReferences methods Pull request #64158
- Standalone source files created via API now use global parse cache and return disposable leases Pull request #64434
- Module resolver API allowing isolated resolveModuleName calls and module resolution overrides Pull request #64299
- tsc -b now schedules projects by dependency depth to reduce builder idle time Pull request #64220
- Incremental caching for all codegen tasks Pull request #64331
- Never type correctly treated as non-mutable-array-like for readonly tuple inference Pull request #64389
- Object property completions now respect configured quote preferences Pull request #64359
- Global diagnostic collection now matches Strada implementation Pull request #64452
- tsconfig plugins parsed for external error reporting Pull request #64397
- Enum generator moved from Herebyfile to scripts directory Pull request #64391
TypeScript improvements this week: Build Orchestrator API, module resolution overrides, incremental codegen caching (up to 80% faster), better project scheduling for tsc -b, and fixes to readonly tuples and quote preferences.
This week's TypeScript updates focus on developer experience and performance: the new Build Orchestrator API provides async project management, module resolution can now be overridden in API programs, and incremental caching for code generation reduces build time by up to 80%. Additionally, the compiler now schedules projects by dependency depth to minimize builder idle time, and we fixed handling of the never type in readonly tuple detection.