[tooltip] Close when active trigger unmounts

[michaldudak]

Summary

• Clear stale active-trigger state when the active trigger unregisters while the tooltip is open.
• Close the tooltip instead of implicitly re-anchoring it to another trigger.
• Cover contained and detached trigger removal.

Bug

When the active trigger unmounts, unregistering removes the DOM node from the trigger map but leaves the active trigger id/element in store state. Conditional or virtualized triggers can then leave the tooltip open against stale anchor state instead of closing.

Reproduction

• Before: https://codesandbox.io/s/v8rgxd?file=/src/App.tsx
• After: https://codesandbox.io/s/n87sc5?file=/src/App.tsx

Test plan

• pnpm test:jsdom popupStoreUtils --no-watch
• pnpm test:chromium TooltipRoot.detached-triggers --no-watch

[pkg-pr-new]

• base-ui-tanstack-start

• vite-css-base-ui-example

  pnpm add https://pkg.pr.new/mui/base-ui/@base-ui/react@4886
  

  pnpm add https://pkg.pr.new/mui/base-ui/@base-ui/utils@4886
  

commit: 2523647

[code-infra-dashboard]

Bundle size

Bundle	Parsed size	Gzip size
@base-ui/react	🔺+527B(+0.11%)	🔺+127B(+0.09%)

Details of bundle changes

Performance

Total duration: 1,521.77 ms 🔺+308.78 ms^(+25.5%) | Renders: 50 ⁽⁺⁰⁾ | Paint: 2,307.71 ms 🔺+477.99 ms^(+26.1%)

Test	Duration	Renders
Tabs mount (200 instances)	313.81 ms 🔺+84.79 ms(+37.0%)	4 (+0)
Menu mount (300 instances)	170.53 ms 🔺+35.67 ms(+26.5%)	2 (+0)
Slider mount (300 instances)	202.91 ms 🔺+35.00 ms(+20.8%)	3 (+0)
Scroll Area mount (300 instances)	112.80 ms 🔺+32.25 ms(+40.0%)	3 (+0)
Menu open (500 items)	100.49 ms 🔺+21.81 ms(+27.7%)	12 (+0)

…and 4 more (+3 within noise) — details

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[michaldudak]

Codex Review (GPT-5.5)

Dominant type: bug-fix. I reviewed the full PR diff against freshly fetched upstream/master; the patch addresses stale tooltip active-trigger state when the owning trigger unregisters, with focused coverage for contained and detached trigger setups.

1. Bugs / Issues (None)

I did not find any concrete blocking or non-blocking issues in the implementation.

Root Cause & Patch Assessment

The fix targets the shared active-trigger reconciliation point in useImplicitActiveTrigger, which is the right layer for detecting that the active trigger id no longer maps to a registered element. Tooltip opts into closing on that condition, while other popup consumers retain the previous “clear stale active trigger” behavior without being forced closed.

The microtask guard is doing useful work here: it avoids closing if the same trigger remounts before the deferred check runs, and it respects canceled onOpenChange events before clearing active-trigger state.

Test Coverage Assessment

Coverage looks proportionate for this bug. The PR adds utility-level coverage for unregistering the active trigger and Chromium tooltip coverage for both contained and detached triggers, including a canceled close path.

I ran:

pnpm test:jsdom popupStoreUtils --no-watch
pnpm test:chromium TooltipRoot.detached-triggers --no-watch
pnpm typescript

All passed. I did not replay the new regression assertions against upstream/master.

Recommendation

Approve ✅

The change is narrowly scoped, covered at the shared utility and Tooltip integration levels, and the relevant targeted tests plus typecheck pass.