[kaiortmanns]

Description

Prevent render loops caused by unstable state setters, unchanged state updates, and resize observer callback churn.

• Store each state value and its stable setter together in the existing hook slot.
• Skip update requests when Object.is reports an unchanged value.
• Initialize lazy state once per hook lifetime, including null and undefined values.
• Keep resize observers attached across renders while invoking the latest callback.
• Document state equality and immutable object/array updates.

Compatibility

Mutating an object or array in place and passing the same reference to its state setter no longer requests a render. Consumers must provide a new reference for changed contents. External firefly-platform consumers have not been validated in this checkout.

Test Evidence

• All 43 data-lit tests pass, including 18 new state and resize regressions.
• tsc -b packages/data-lit passes.
• git diff --check passes.

Regression coverage includes stable setters, repeated equal writes, NaN and signed zero semantics, nullish initialization and updates, independent state slots, observer reuse, latest callback delivery, memo stability, unchanged-width suppression, and unmount/remount cleanup.

PR Checklist

• Add focused regression tests.
• Run the complete data-lit test suite and package typecheck.
• Document the same-reference state update compatibility change.
• Screenshots: N/A (no visual UI changes).
• Feature flags: N/A (none added or removed).
• CI checks: pending.

Jira Ticket

N/A (no ticket provided).

Related PRs

None.