Reproduction link or steps

1. package.json

echo '{"name":"foo","scripts":{"build":"tsdown"},"devDependencies":{"tsdown":"^0.12.9"}}' > package.json

2. Create source file

mkdir src && echo 'export const test = "hello"' > src/index.ts

3. Install and build

pnpm install && pnpm run build

Run on Windows - observe inconsistent path separators in logs.

What is expected?

Consistent path separators in build logs. Since config & docs uses forward slashes, logs should show:

ℹ entry: src/index.ts
...
ℹ dist/index.mjs

What is actually happening?

ℹ entry: src\index.ts     ← backslash
ℹ dist/index.mjs          ← forward slash

Entry path uses backslashes while output path uses forward slashes, despite config specifying forward slashes.

Any additional comments?

First level uses forward slashes, but nested paths use backslashes.

Build works correctly, it's a cosmetic issue.