`tsc --watch` doesn't recompile on file change

[haines]

Steps to reproduce

I haven't been able to reduce this to a minimal reproduction yet. I will continue trying but in the interim, any tips that would help debug the issue would be much appreciated.

I'm running tsc --build --watch from one package in a monorepo whose tsconfig.json has references to other packages within the monorepo.

Node v24.18.0
macOS 26.5.2 arm64

Behavior with typescript@6.0.3

Changing files in the package triggers a rebuild.

Behavior with typescript@7.0.2

Changing files in the package does not trigger a rebuild.

Screen.Recording.2026-07-30.at.13.12.53.mov

[rkistner]

I'm running into what appears to be the same issue. This appears to be correlated with project size (number of files and/or referenced projects). Reproduce on this branch: powersync-ja/powersync-service#745

To reproduce, in the repo root:

1. pnpm install
2. ./node_modules/.bin/tsc -b -w

The build itself is fast (1-2s on my machine). But after that, the process appears to hang for 45s, with CPU usage for tsc hovering around 175%. During that 45s, no changes to source files are picked up, and Ctrl+C does is delayed until the end of the 45s period. After that 45s, a file change would be picked up instantly, with a new 45s delay following again.

If I run this on a smaller project, say in packages/service-core for the repo above, the delay is shorter, but the issue is still there.

Tested on Ubuntu 26.04.

Andrew Haines (@haines) Do you see the same - high CPU usage after building, and then eventually recovering and detecting a change again?

[jakebailey]

Can you please try the nightly instead of 7.0.2?

[rkistner]

Jake Bailey (@jakebailey) Using 7.1.0-dev.20260804.1 appears to resolve the issue for me: No high CPU usage after building; detecting changes and Ctrl+C run instantly.

[haines]

@haines Do you see the same - high CPU usage after building, and then eventually recovering and detecting a change again?

Yes, this is exactly what happens. I had just never been patient enough to wait for the eventual recovery 😅

@jakebailey Using 7.1.0-dev.20260804.1 appears to resolve the issue for me: No high CPU usage after building; detecting changes and Ctrl+C run instantly.

Likewise 🎉