fix(modal): prevent sheet gesture crash with late-bound breakpoints

[ShaneK]

Issue number: internal

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What is the current behavior?

Currently, when an ion-modal's breakpoints are set after the component has loaded, sortedBreakpoints stays empty. breakpointsChanged had no @Watch, so it only ran once from the manual call in componentDidLoad. present() still recalculates isSheetModal to true from the late-set breakpoints (added in #30839), so the sheet gesture initializes with an empty breakpoints array and throws Reduce of empty array with no initial value on the breakpoints.reduce(...) in sheet.ts when the sheet is swiped, which breaks swiping entirely.

This shows up with framework bindings that land after the web component loads, e.g., an inline ion-modal inside an Angular component rendered through a plain router-outlet with zoneless change detection. It doesn't reproduce with zone change detection, with ModalController.create, or with the modal inside ion-router-outlet, since those set breakpoints before the modal presents.

What is the new behavior?

Now breakpointsChanged has @Watch('breakpoints'), so breakpoints set after the component loads update sortedBreakpoints. This mirrors how trigger/triggerChanged already handles late binding (a watch plus a manual call in componentDidLoad). The sheet gesture then gets the real breakpoints and swiping works.

Does this introduce a breaking change?

• Yes
• No

Other information

Sheet modal preview:

• https://ionic-framework-git-fix-modal-late-breakpoints-ionic1.vercel.app/src/components/modal/test/sheet

Note that the preview won't show this working, but will show the modal at least isn't broken from this change.

Current dev build:

8.8.10-dev.11781019195.14a7eeaf

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Project	Deployment	Actions	Updated (UTC)
ionic-framework	Ready	Preview, Comment	Jun 9, 2026 3:30pm

[thetaPC]

LGTM