TypeScript 7.1 Iteration Plan

Language and Compiler

• Stabilize API
  • Content Mapper API
  • Emit API
  • Language Service API
• Support type On Import Attributes
• Investigate Node 26 Package Maps
• Add es2026 option for lib and target
• Support Source Phase Imports
• lib.d.ts Updates for New Iterator Methods
• Promise.allKeyed and Promise.allSettledKeyed
• lib.d.ts Updates for DOM

Editor Productivity

• Replace Existing API Integrations in VS Code
• Investigate New Expandable Hover API in LSP
• Investigate Multi-document Highlighting API in LSP
• Investigate Region Diagnostics in LSP

Performance

• Faster Union Type Construction
• Lazily Collect Source File Identifiers
• Fast Path for Assignment Narrowing on Unions
• Fast Path for Equality & switch/case Narrowing on Unions
• Optimize Representations of Checker-Specific Side-Tables
• Experiment with Algorithms for Distributing Files Across Type-Checkers
• Probably more!

Infrastructure

• Static Analysis for Nil Checking and Casts
• Migrate repository to microsoft/TypeScript
  • Overhaul of Publishing Pipeline
• Publish wasm (wasip1?) Build
• Publish Android ARM64 Build
• Flaky Diagnostics Detection

Website

• Monaco LSP Feedback
• Getting Playground Running with wasm
• Speed up website builds

Start with the milestone table and review the linked TypeScript issues and typescript-go pull requests for the Language and Compiler, Performance, and Infrastructure sections. No specific file, test, or entry point is named, and completion is represented by progress across the listed release-plan items rather than one independently defined change.