Bay Area post-close roof leak. Discovered rotten decking

Hi all. I’m in the Bay Area.

We closed in summer and moved in about a month later. After the first rain event post-move-in, we found a significant amount of water on the interior floor. In hindsight, there may have been an earlier sign of moisture during a pre-move visit, but at the time it wasn’t clear what the source was (we hadn’t moved in yet).

During roof repair later, the roofer opened the roof around a penetration and found wet/rotted decking and saturated materials that look consistent with longer-term moisture intrusion (not just a one-time event). I have photos from the repair and invoices.

Pre-sale inspections:

General home inspection was done in dry weather and didn’t report active leaks.

Separate roof inspection noted prior repairs and said the roof appeared functional.

Seller disclosures: no mention of leaks/water intrusion (as far as I can tell).

A realtor (not our agent) mentioned this could potentially be a nondisclosure situation. I’m not looking for formal legal advice, just trying to sanity-check next steps before speaking to a real estate litigation attorney.

Questions:

1. Does this sound like a plausible nondisclosure/misrepresentation case in CA?

2. What evidence tends to matter most?

3. What should I do right now to preserve evidence and avoid mistakes?

Thanks in advance.