Alright thank you

There is no SEO benefit with client components?

Yes, client components do not directly improve SEO.

they are supposedly pre rendered on client

should not they be accessible for google bot?

Client-side components, although rendered on the client, might not always be fully accessible or indexed by Googlebot in the same way that server-rendered content or static content would be.

how to make them fully accessible?

Yes, they are pre-rendered, but you will only ship the initial HTML you can build on the server.
For example, if your UI depends on fetch calls that are made on the client side (using useEffect for example) you will need to wait for the user to download the JS code from the page to be able to fetch the data, and then you will render the full page.
However, if you do these db/fetch calls on the server, you can ship the whole HTML code directly to the user without waiting for the JS code to be downloaded and this is good for SEO.

You can look at the benefits of server side rendering in the Next.js doc:
https://nextjs.org/docs/app/building-your-application/rendering/server-components#benefits-of-server-rendering

In addition to that, client components is not a deoptimization. It can affect SEO but it can also not affect SEO if the initial state is provided from the server

that is where my problem lies

say my backend is a separate service available at api.com

say i have a route /product/123 which has link to another product - /product/124

if my product component is composed of a server comp (for data fetching from api.com) and client component for showing UI

if user navigates to /product/124, it implies one hit on the nextjs server just for fetching data from api.com and then rendering it back on browser.

while this will be good for SEO, i am making one unnecessary call to server..

yes but

you can cache your respond of /prroduct/124

and let the static part to be for SEO and have the dynamic part to be whatever your user needs that doesnt need SEO

yes got that but if the api called for /product/124 is personalized per user i dont have any caching benefit too

in that case, why would you need SEO if /product/124 is personalized per user...

just serve static content (that doesn't require hitting /product/124) and let client do the fetching to /product/124

for a non-registered user i still want to index the metadata of product 124 on google

I cant go with static generation because the data for 124 keeps changing periodically..

You can use server component to generate the metadata of product 124, and then use client component to update its data as requested. The one on the server component can be cached as to not get refreshed every user request but for everry 3-5 seconds, or 1 hour? idk. Something like that

yes agree, but say user navigates on the browser from product 124 to 125 -->
1. now again a hit on nextjs server + make api call or mostly used cached value from next cache
2. make api call from client to get actual personalized data

i was looking for a way to avoid step #1

sooo basically shallow routing

not familiar yet with that maybe you can create a new post.

what im trying to say is that if you did a fetch in the server, converting a server comp to client comp wont affect the SEO if set properly

i would still not recommend converting the entire page with "use client"

just one more clarification, if i convert server comp to client comp - how do i fetch data in the client component during the server rendering phase?
i have been understanding its only possible with Server Component passing data to Client component w next15 app router

i did have a post but did not get traction yet : https://nextjs-forum.com/post/1314688327764414494
need to learn more of shallow routing, based on another response i understood it needs more testing and not super elegant way: https://nextjs-forum.com/post/1194236734821642291#message-1314821724285567059

its hard to fetch data in client component during server rendering phase. Because effectively, you are like "emulating" the client component in the server. Even if you managed to fetch those data in the client comp in the server, its hard to prevent the server logic into running in the client due to how the hydration process is done.
Also that you'd be importing uneccesary server code into the client which can increase bundle size

Its better to fetch in server component and pass it to a client component

the idea that client component are prerendered is to promote not only unaffected SEO, but also progressive enhancement. Which is speaking that if you have JS disabled, it still have the initial styles of the client component, and the data that was passed from the server. (as a side effect, doesn't kill off SEO if you fetched it from the server)

You can bump the thread once a day just fyi