I work and have apt in NYC for more than 184 days. Home is LA. Wife works in LA. File jointly federally and in Calif. NY says I am resident for NY tax. How do I file for NY? Do I file part year resident/non resident form showing only my income? What about community income on NY return, such as jointly held interest/dividend income in Calif? Does that income get allocated partially or fully to NY?

You are a NY resident, and your wife is a CA resident. You file a NY resident return (including NYC resident tax). If your wife has no NY-source income, you can file the NY resident form as Married Filing Single, and that way report only your income (not your wife's). You will have to include any income that has you as the primary owner - so interest and dividends in accounts that are under your SS number. Now, it's possible to split income on joint accounts, but that will require a bit of documentation to back up the split. Meanwhile your wife files as CA resident, again as Married Filing Single, and reports her income to CA.