Bug/regression report: PS 26.6 breaks "postMessage" communication between the host and local webview

Photoshop
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1

Hi,

I found out that Photoshop 26.6 has a regression regarding the communication between the extension (host) and the webview.

This bug completely breaks our extension since we rely on the host and the local webview to be able to communicate in both ways.

Here is an example to download: repro-webview-communication.zip (3.4 KB)

The extension once loaded should look like this, without the bug, on the versions 26.5 and 26.4.1 (I did not test prior versions)

Screenshot 2025-05-07 at 12.43.20
Screenshot 2025-05-07 at 12.43.20796×704 44.7 KB

Here the 2 way communication is successful.

On Photoshop 26.6 it looks like this:

Screenshot 2025-05-07 at 12.48.29
Screenshot 2025-05-07 at 12.48.29796×700 32.2 KB

You can see that the host could successfully receive a message coming from the webview.
But the webview fails to receive the message from the host.
The 2 way communication is broken, we only got 1 way working: From the webview to the host but not the opposite.

Are you aware of this regression?
Is there a better place to report it maybe?

Best regards

2

I found out that changing the setting of “enableMessageBridge” affects this.

this regression only happens for "enableMessageBridge": "localOnly"
Example manifest (from .zip):

  "requiredPermissions": {
    "localFileSystem": "request",
    "webview": {
      "allow": "yes",
      "allowLocalRendering": "yes",
      "domains": "all",
      "enableMessageBridge": "localOnly"
    },
  },

Changing "enableMessageBridge" value to "localAndRemote" fixes the problem: the 2 way communication is restored.

This is not a great workaround since it means that as a developer I need to ask for extended permissions that should not be needed, since the webview is a local file here. But that works.

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