fix(tab-bar): prevent keyboard controller memory leak on rapid mount/unmount

[ShaneK]

Issue number: resolves internal

---

What is the current behavior?

When ion-tab-bar is rapidly mounted and unmounted, a race condition in connectedCallback can cause the keyboard controller to be created after the component has been disconnected. This results in orphaned event listeners (keyboardWillShow, keyboardWillHide) on the window object that are never cleaned up, causing a memory leak.

What is the new behavior?

The keyboard controller is now properly destroyed in all scenarios:

• If the component is disconnected while createKeyboardController is pending, the promise is tracked and destroyed when it resolves
• If a new connectedCallback runs before the previous async completes, the stale controller is destroyed

The promise tracking pattern ensures only the most recent async operation assigns its result

Does this introduce a breaking change?

• Yes
• No

Other information

Current dev build:

8.7.17-dev.11767895575.16ea7cef

I was unable to find a way to create tests that accurately identified if this problem was occurring. Memory leaks are notoriously difficult to created automated tests for. I ultimately removed my previous attempts because I didn't want to give a false sense of security.

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Project	Deployment	Review	Updated (UTC)
ionic-framework	Ready	Preview, Comment	Jan 13, 2026 10:29pm

[brandyscarney]

Maybe this doesn't need to be done on this PR, but I feel like we do this same code in so many places that we should consider making it a utility.

[ShaneK]

It looks like this particular pattern is only specifically done in tab bar and footer (unless I'm missing something?), so I'm not sure if that's worth extracting right now

[brandyscarney]

I mostly meant the code that is destroying like this:

ionic-framework/core/src/components/select/select.tsx

Lines 376 to 379 in 1c89cf0

	if (this.notchController) {
	this.notchController.destroy();
	this.notchController = undefined;
	}

We also disconnect in a lot of places:

ionic-framework/core/src/components/select/select.tsx

Lines 382 to 385 in 1c89cf0

	if (this.validationObserver) {
	this.validationObserver.disconnect();
	this.validationObserver = undefined;
	}

It seems like we could make this into a utility or something, but that's not an issue for your PR.

[thetaPC]

Let's make a ticket to circle back on adding the utility.

[ShaneK]

@thetaPC Done! This will be FW-7030