fix(ui): persist follow-up prompt defaults

[xsfX20]

Summary

• persist provider default values when saving follow-up prompts so untouched prompt/temperature/base URL fields are still written
• use the normalized provider values when checking required inputs so default-backed fields do not block save
• fix the options input value lookup to read the selected option by key instead of the whole input descriptor

Testing

• git diff --check
• pnpm eslint packages/ui/src/ui-component/extended/FollowUpPrompts.jsx (fails locally because this checkout does not currently have the eslint binary installed)

[gemini-code-assist]

Code Review

This pull request refactors the FollowUpPrompts component by introducing helper functions to centralize configuration handling and default value logic, while also ensuring state synchronization after saving. Review feedback highlights a validation bug where the value 0 is incorrectly treated as invalid and suggests simplifying nullish checks using the == null idiom for improved readability.

[gemini-code-assist]

This check incorrectly treats 0 as an invalid value, which would disable the save button if a user sets a field like 'Temperature' to 0. Using value == null will correctly handle 0 as a valid input while still checking for null and undefined.

Suggested change

	if (!value || value === '') {
	if (value == null || value === '') {

[gemini-code-assist]

The check for undefined and null can be simplified. Using loose equality (== null) checks for both null and undefined, which is a standard idiom in JavaScript and aligns with the general rules for this repository. This improves readability.

Suggested change

	return value !== undefined && value !== null && value !== '' ? value : inputParam.default
	return value != null && value !== '' ? value : inputParam.default

References

1. In JavaScript/TypeScript, use loose equality (== null) as a standard idiom for a 'nullish' check that covers both null and undefined.

[gemini-code-assist]

The check for undefined and null can be simplified. Using loose equality (== null) checks for both null and undefined, which is a standard idiom in JavaScript and aligns with the general rules for this repository. This improves readability.

Suggested change

	if ((providerConfig[key] === undefined || providerConfig[key] === null || providerConfig[key] === '') && inputParam.default !== undefined) {
	providerConfig[key] = inputParam.default
	}
	if ((providerConfig[key] == null || providerConfig[key] === '') && inputParam.default !== undefined) {
	providerConfig[key] = inputParam.default
	}

References

1. In JavaScript/TypeScript, use loose equality (== null) as a standard idiom for a 'nullish' check that covers both null and undefined.

[xsfX20]

Addressed the validation issue from the review.

• allow 0 to pass required-field validation for follow-up prompt settings
• keep empty-string / null / undefined blocked as before

Pushed in 1843e519.

[xsfX20]

Follow-up update: I pushed one more small cleanup in 48a0e372 to address the readability suggestion from the Gemini review as well.

• keep the earlier 0 validation fix in place
• simplify the repeated nullish checks to the == null idiom where we only want to treat null / undefined as missing

Scope is still intentionally narrow to the follow-up prompts config flow.