debug.breakpoints always returns empty list after reopening vscode

[GYK90]

Issue Type: Bug

problem summary

As title. debug.breakpoints always returns empty list after I reopen vscode.

Reproduce steps:

1. in a webview, create a button. Add callback to the button so that after clicking the button, console.log this:
   debug.breakpoints
2. open a python file and put some breakpoints in it. Make sure they are enabled. Then close vscode.
3. open vscode. Make sure the breakpoints are still enabled. Then click the button in step one.

Expected:
console.log should show some Breakpoints in an Array.

Actual result:
There are no breakpoints in the Array.
If I click the button for second time, console.log shows the correct breakpoints in the Array.

VS Code version: Version: 1.55.2021071201
OS: Darwin x64 20.5.0
OS version: macOS Big Sur version 11.4 (20F71)

[weinand]

This is the expected behavior: first access triggers the loading of breakpoints from VS Code to extension. Due to asynchronous communication between VS Code and extensions, breakpoints are not available on first access.

We do not sync breakpoints on extension activation because most extensions are not interested in breakpoints. For this reason synchronisation starts on first access.

But we need to document this behaviour.

[GYK90]

thank you @weinand for quick and clear answer. That makes sense to me. I found a solution to call the function when we render the UI first. This solves the problem.

[weinand]

Just adding a debug.breakpoints; expression to your activation function should be enough to start syncing early.