Jest tests don't use isolated modules

[withinfocus]

The unit tests in this repo could be improved to use isolatedModules as true.

[claude]

Issue Analysis

Type: Feature Request / Code Quality Improvement
Priority: Medium

Summary

This issue requests enabling the isolatedModules: true TypeScript compiler option in the Jest configuration. This is a valuable improvement for test isolation and build consistency.

Current State

• Jest config uses ts-jest with ESM support
• TypeScript config includes strict compiler options but lacks isolatedModules
• Tests are working but could benefit from better module isolation

Benefits of isolatedModules: true

1. Faster compilation: Enables single-file transpilation without type checking dependencies
2. Better test isolation: Ensures each module can be compiled independently
3. Build consistency: Matches bundler behavior (like esbuild, Rollup) that process files in isolation
4. Earlier error detection: Catches issues where code relies on cross-file type inference

Implementation

This would require:

1. Adding isolatedModules: true to tsconfig.json or creating a separate test tsconfig
2. Updating Jest configuration to use the isolated modules setting
3. Fixing any code that doesn't work with isolated compilation (typically rare)

Assessment

• No duplicate issues found
• Low risk change with clear benefits
• Aligns with modern TypeScript best practices
• Improves CI/build performance

This is a solid improvement that should be implemented when time permits.