[amp-story] When not coming from cache, you should be able to prerender assets without playing the story.

Description

Right now, the only way to display an asset is to set the visibility state to visible. However, this play the story. You cannot render the story if you never played it before.

As discussed with @newmuis during the working group, this is to prevent security issues. This prevent tiers services from getting information on the user.

However, this prevent certain worklflow, where a story could be visible but should not play, as it is not the focus of attention.

Developers should have a way to display assets without playing the story, either using an additional visibility, or with an additional state.

Reproduction Steps

On this sandbox, you can try to change the story visibilityState : https://z9ce0.csb.app/

Relevant Logs

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Browser(s) Affected

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OS(s) Affected

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Device(s) Affected

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AMP Version Affected

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[jridgewell]

We cannot make changes to the privacy features of PRERENDER state. We could make it so that PAUSED state allows buildCallback.

[samouri]

@edoudou + @newmuis: The privacy preserving characteristics of PREVIEW and PRERENDER modes depend on an AMP Optimizer rewriting subresource URLs to point to the cache. For example, redirecting all <amp-img> tag src attributes to point to a cache address instead of the original origin address. This concept doesn’t apply off cache.

PRERENDER might work for your use case as long as all the components you care about have prerenderAllowed set to true.