r/javascript • u/syrusakbary • 2d ago

Wasmer SDK: Open Source alternative to WebContainers

https://wasmer.io/posts/wasmer-local-sandboxes-for-ai-agents
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u/Beautiful-Energy2169 2d ago

If you go the cross-origin isolation route for threads, set COOP/COEP per path rather than site-wide. We turned them on globally and the overlay checkout stopped rendering: under isolation a cross-origin iframe has to send its own COEP header, and that payment provider doesn't. Only the two routes that actually run wasm carry the headers now, and we leave /pricing and /account alone.

2

u/syrusakbary 1d ago

Funnily enough, it happened the same for us (for payments), so we had to unset COOP/COEP there

2

u/Beautiful-Energy2169 1d ago

Credentialless iframes skip the COEP check but load cookieless, so checkout still breaks.