SITES-40700: fix linting/React

[AmyJZhao]

Description

Related Issue

Motivation and Context

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[Copilot]

Pull request overview

This PR modernizes linting across the monorepo (moving to ESLint v9 flat config) and applies a wide set of formatting/type-import fixes, with a few refactors in React hooks/components to satisfy stricter lint rules.

Changes:

• Introduces shared ESLint flat-config (eslint.base.mjs) and per-package eslint.config.mjs, plus workspace lint scripts.
• Applies repo-wide lint-driven edits (type-only imports, trailing commas, object key ordering, arrow-function conversions, etc.).
• Refactors parts of uix-host-react hooks/components to address React hook dependency and lint constraints.

Reviewed changes

Copilot reviewed 70 out of 73 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
packages/uix-host/src/utils/comparePackagesVersions.ts	Formatting changes to satisfy lint rules (expanded if blocks).
packages/uix-host/src/utils/compareExtensions.ts	Type-only imports + stable string sorting with localeCompare.
packages/uix-host/src/port.ts	Lint/format updates; minor refactors (regex exec, arrow typeguards, parameter commas).
packages/uix-host/src/port.test.ts	Lint/format updates and import reordering for mocked connectIframe.
packages/uix-host/src/metrics.ts	Lint cleanup and minor refactors in metrics wrapper + runtime polling formatting.
packages/uix-host/src/host.ts	Type-only imports and formatting; minor statement/arg ordering adjustments.
packages/uix-host/src/extensions-provider/mute.ts	Type-only import + trailing comma to satisfy lint rules.
packages/uix-host/src/extensions-provider/extension-registry.ts	Type-only imports + formatting; minor lint suppressions.
packages/uix-host/src/extensions-provider/extension-registry.test.ts	Test formatting changes and lint suppression for require.
packages/uix-host/src/extensions-provider/composition.ts	Type-only imports + simplified arrow return.
packages/uix-host/src/dom-utils/iframe-normalizers.ts	Type-only imports split + formatting adjustments.
packages/uix-host/src/dom-utils/iframe-normalizers.test.ts	Formatting fixes (trailing commas, blank lines).
packages/uix-host/src/dom-utils/attribute-normalizers.ts	Minor formatting (padding lines).
packages/uix-host/src/dom-utils/attribute-normalizers.test.ts	Import reordering + formatting.
packages/uix-host/src/debug-host.ts	Type-only imports split + formatting updates.
packages/uix-host/package.json	Adds lint script for package-local eslint runs.
packages/uix-host/eslint.config.mjs	Adds package ESLint flat-config entrypoint.
packages/uix-host-react/src/hooks/useHost.ts	Converts to export const + type-only import cleanup.
packages/uix-host-react/src/hooks/useExtensions.ts	Refactors memo/deps handling, subscriptions, and unload handling to satisfy hooks lint.
packages/uix-host-react/src/hooks/useExtensions.test.tsx	Import cleanup and formatting updates for lint.
packages/uix-host-react/src/hooks/useExtensionListFetched.ts	Converts to export const + type-only import cleanup.
packages/uix-host-react/src/extension-context.ts	Type-only import cleanup + formatting.
packages/uix-host-react/src/components/GuestUIFrame.tsx	Refactors connection/resizing effects; removes default export; adds memo/callback refs.
packages/uix-host-react/src/components/ExtensibleWrapper/UrlExtensionProvider.ts	Type-only imports + functional style conversions; formatting updates.
packages/uix-host-react/src/components/ExtensibleWrapper/UrlExtensionProvider.test.ts	Test updates (https URLs, formatting, import changes).
packages/uix-host-react/src/components/ExtensibleWrapper/ExtensionManagerProvider.ts	Type-only imports + functional style conversions; formatting updates.
packages/uix-host-react/src/components/ExtensibleWrapper/ExtensionManagerProvider.test.ts	Test restructuring/formatting + global fetch mocking adjustments.
packages/uix-host-react/src/components/ExtensibleWrapper/ExtensibleWrapper.tsx	Type-only imports + formatting; adjusts scope typing to Record<string,string>.
packages/uix-host-react/src/components/ExtensibleComponentBoundary.tsx	Type-only import cleanup + minor component formatting; react-refresh lint suppression.
packages/uix-host-react/src/components/Extensible.tsx	Refactors helper + effects/deps to satisfy hooks lint; removes default export.
packages/uix-host-react/src/components/Extensible.test.tsx	Formatting + lint suppressions (max-lines-per-function) and minor mock reshaping.
packages/uix-host-react/package.json	Adds lint script (with --fix).
packages/uix-host-react/eslint.config.mjs	Adds React-enabled package ESLint flat-config entrypoint.
packages/uix-guest/src/index.ts	Import ordering/type-only adjustments + formatting.
packages/uix-guest/src/guest.ts	Formatting + changes around timeouts and postMessage payload ordering.
packages/uix-guest/src/guest-ui.ts	Import splitting (type vs value) + formatting + declare ordering.
packages/uix-guest/src/guest-server.ts	Import ordering/type-only tweaks.
packages/uix-guest/src/debug-guest.ts	Type-only import split + formatting.
packages/uix-guest/package.json	Adds lint script for package-local eslint runs.
packages/uix-guest/eslint.config.mjs	Adds package ESLint flat-config entrypoint.
packages/uix-core/src/value-assertions.ts	Formatting + trailing commas.
packages/uix-core/src/types.ts	Formatting + trailing commas + generic formatting.
packages/uix-core/src/tunnel/tunnel.ts	Refactors cleanup placement + adds lint suppressions (random, ignored exceptions).
packages/uix-core/src/tunnel/tunnel.test.ts	Formatting + minor data object key ordering.
packages/uix-core/src/tunnel/tunnel-messenger.ts	Safer hasOwnProperty usage + type-only imports split + formatting.
packages/uix-core/src/tunnel/tunnel-messenger.test.ts	Formatting + trailing commas.
packages/uix-core/src/rpc/call-sender.ts	Formatting + adds max-params suppression; minor ordering changes.
packages/uix-core/src/rpc/call-sender.test.ts	Import cleanup + formatting; avoids deprecated matcher style warnings.
packages/uix-core/src/rpc/call-receiver.ts	Formatting + argument ordering in response tickets.
packages/uix-core/src/rpc/call-receiver.test.ts	Import cleanup + formatting.
packages/uix-core/src/remote-subject.ts	Import order/type-only adjustments + formatting.
packages/uix-core/src/promises/timed.ts	Formatting + trailing commas.
packages/uix-core/src/promises/promise-wrappers.test.ts	Formatting + avoids deprecated matcher style warnings.
packages/uix-core/src/object-walker.ts	Type cleanup and formatting; refines function type constraints.
packages/uix-core/src/object-simulator.ts	Refactors receiver/sender creation; adjusts binding/caching logic; formatting/lint suppressions.
packages/uix-core/src/object-simulator.test.ts	Snapshot/test updates due to simulator changes + formatting.
packages/uix-core/src/namespace-proxy.ts	Type-only import + formatting + minor key ordering.
packages/uix-core/src/message-wrapper.ts	Formatting + trailing commas.
packages/uix-core/src/logging-formatters.ts	Adds explicit ignored-exception suppression; formatting.
packages/uix-core/src/emitter.ts	Switches to type-only import + formatting + trailing commas.
packages/uix-core/src/debuglog.ts	Formatting and some property ordering changes; minor refactors.
packages/uix-core/src/debug-emitter.ts	Type-only imports split + formatting and payload ordering change.
packages/uix-core/src/cross-realm-object.ts	Formatting + explicit function casting; trailing commas.
packages/uix-core/src/mocks/mock-finalization-registry.ts	Adds jest global comment + lint suppression for static mock.
packages/uix-core/src/helpers/jest.messagechannel.cjs	Adds eslint-disable header for CJS require + node globals.
packages/uix-core/package.json	Adds lint script for package-local eslint runs.
packages/uix-core/eslint.config.mjs	Adds package ESLint flat-config entrypoint.
package.json	Adds workspace lint runner + upgrades eslint/prettier toolchain deps to support flat config.
eslint.base.mjs	New shared ESLint flat configuration factory used by packages.
e2e/all-versions/host-app/package-lock.json	Updates resolved registry URLs for e2e lockfile dependencies.
e2e/all-versions/guest-app/package-lock.json	Updates resolved registry URLs for e2e lockfile dependencies.
.eslintrc.cjs	Removes legacy ESLint config in favor of flat config.

Files not reviewed (2)

• e2e/all-versions/guest-app/package-lock.json: Language not supported
• e2e/all-versions/host-app/package-lock.json: Language not supported

Comments suppressed due to low confidence (2)

packages/uix-guest/src/guest.ts:263

• invokeAwaiter() sets a timeout whose callback returns Promise.reject(...), but that rejection is not wired to the returned promise (and can become an unhandled rejection when the timer fires). As written, the timeout never rejects the operation. Implement this as a real timeout (e.g., Promise.race between invokeChecker(...) and a promise that rejects in the timer, with proper clearTimeout in finally), or remove this timer if timeoutPromise already enforces the desired limit.
  packages/uix-host/src/extensions-provider/extension-registry.ts:149
• extensionRegistryExtensionsProvider() has an unreachable return Promise.resolve({}); after already returning the fetchExtensionsFromRegistry(...).then(...) chain. This is dead code and can be removed to avoid confusion (and potential lint warnings about unreachable code).

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[Copilot]

depsKey is derived via JSON.stringify(deps), which can throw on circular values and also collapses non-serializable deps (e.g., functions become null in arrays). That can cause the hook to stop re-running configFactory when deps actually change, or crash at runtime for certain deps. Prefer using the deps array directly in the dependency list (and require callers to pass stable deps), or compute a safe/stable key that won't throw (e.g., join of primitives) and document the constraint.

[Copilot]

makeReceiver() looks up receiverTicketCache using the original fn, but stores the ticket using boundFunction as the key. When parent is provided, subsequent visits will call get(fn) again (miss) and create a new ticket each time, which breaks stability/caching of function IDs and can create multiple receivers for the same method. Either always cache by the original fn, or if binding is required, compute the cache key consistently (e.g., look up/store using the same boundFunction value).

Suggested change

	this.receiverTicketCache.set(boundFunction, fnTicket);
	this.receiverTicketCache.set(fn, fnTicket);