## Summary
In Node.js, `tty.ReadStream` sets `isTTY` as a simple instance property
(`this.isTTY = true`), making it naturally writable. Deno's polyfill
used a getter-only property definition, preventing assignment.
Some npm packages need to override `isTTY` at runtime. For example,
Playwright's test server sets `process.stdin.isTTY = undefined` to
prevent reporters from blocking on user input during UI mode
(microsoft/playwright#37867).
This aligns stdin with the stdout/stderr fix from #26130, ensuring all
stdio streams behave consistently with Node.js.
## Refs
-
6a1a3ba045/lib/tty.js (L71)
-
3a5a32d26d/packages/playwright/src/runner/testServer.ts (L257-L266)
Co-authored-by: Claude <noreply@anthropic.com>
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