[Fiber] Add additional debugInfo to React.lazy constructors in DEV #34137
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We read a timestamp for start/end now.
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This was referenced Aug 9, 2025
eps1lon
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…#34144) Normally, we pick up debug info from instrumented Promise or React.Lazy while we're reconciling in ReactChildFiber when they appear in the child position. We add those to the `_debugInfo` of the Fiber. However, we don't do that for for Lazy in the Component type position. Instead, we have to pick up the debug info from it explicitly in DevTools. Likely this is the info added by #34137. Older versions wouldn't be covered by this particular mechanism but more generally from throwing a Promise. <img width="592" height="449" alt="Screenshot 2025-08-08 at 11 32 33 PM" src="https://github.com/user-attachments/assets/87211c64-a7df-47b7-a784-5cdc7c5fae16" />
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Similar to #34137 but for Promises. This lets us pick up the debug info from a raw Promise as a child which is not covered by `_debugThenables`. Currently ChildFiber doesn't stash its thenables so we can't pick them up from devtools after the fact without some debug info added to the parent. It also lets us track some approximate start/end time of use():ed promises based on the first time we saw this particular Promise.
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This creates a debug info object for the React.lazy call when it's called on the client. We have some additional information we can track for these since they're created by React earlier.
We can track the stack trace where
React.lazywas called to associate it back to something useful. We can track the start time when we initialized it for the first time and the end time when it resolves. The name from the promise if available.This data is currently only picked up in child position and not component position. The component position is in a follow up.
This begs for ignore listing in the front end since these stacks aren't filtered on the server.