Missing component sourcemaps with JIT and CLI cache enabled

[urrang]

Command

serve

Is this a regression?

• Yes, this behavior used to work in the previous version

The previous version in which this bug was not present was

18.2.3

Description

We have a large Angular app, and for the time being we're using JIT mode during local development for faster change-reload cycles.

Since upgrading to Angular 19 we've noticed component sourcemaps are missing in the Sources panel of the browser dev tool. When placing debugger statements in our code the browser just points at the end of the component template. This is not a problem when AOT is enabled.

I noticed after some debugging that disabling the Angular CLI cache resolves the problem. Running ng cache clean or removing the .angular directory and restarting the dev server (with caching) does not help. Caching needs to be completely disabled for sourcemaps to work.

Caching enabled:

Caching disabled:

Minimal Reproduction

https://github.com/urrang/ng19-sourcemap-repro

Command: ng serve

The repro app has a debugger statement in the button's click handler. On the main branch the problem should be reproducible. On the cache-disabled branch CLI's cache has been disabled and the debugger should work as expected.

Exception or Error

Your Environment

Angular CLI: 19.1.8
Node: 22.13.1
Package Manager: npm 10.9.2
OS: darwin arm64

Angular: 19.1.7
... animations, common, compiler, compiler-cli, core, forms
... platform-browser, platform-browser-dynamic, router

Package                         Version
---------------------------------------------------------
@angular-devkit/architect       0.1901.8
@angular-devkit/build-angular   19.1.8
@angular-devkit/core            19.1.8
@angular-devkit/schematics      19.1.8
@angular/cli                    19.1.8
@schematics/angular             19.1.8
rxjs                            7.8.2
typescript                      5.7.3
zone.js                         0.15.0

Anything else relevant?

No response

[urrang]

Just noticed this is probably a duplicate of #29656. Sorry about that, I must have only looked for existing issues on the angular repo, not angular-cli. Leaving this up for now since it contains a bit more info, but feel free to close it.