[Bug]: invalid_community on remote reply

[julianlam]

Requirements

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Summary

I was unable to federate a reply to a lemmy instance running on sopuli.xyz. The reply had inReplyTo set, so the community should be irrelevant.

If not, is it because audience does not match the lemmy community?

Steps to Reproduce

N/A

Technical Details

The returned error was { error: 'invalid_community' }

The full payload is below:

{                                                                                                                                                                        
  '@context': 'https://www.w3.org/ns/activitystreams',                                                                                                                   
  actor: 'https://community.openbeta.io/uid/15',                                                                                                                         
  id: 'https://community.openbeta.io/post/1925#activity/create/1734717171439',                                                                                           
  type: 'Create',                                                                                                                                                        
  to: [                                                                                                                                                                  
    'https://www.w3.org/ns/activitystreams#Public',                                                                                                                      
    'https://sopuli.xyz/u/guslipkin'                                                                                                                                     
  ],                                                                                                                                                                     
  cc: [                                                                                                                                                                  
    'https://community.openbeta.io/uid/15/followers',                                                                                                                    
    'https://sopuli.xyz/u/guslipkin',                                                                                                                                    
    'https://aussie.zone/u/gazter'                                                                                                                                       
  ],                                                                                                                                                                     
  object: {                                                                                                                                                              
    '@context': [ 'https://www.w3.org/ns/activitystreams', [Object] ],                                                                                                   
    id: 'https://community.openbeta.io/post/1925',                                                                                                                       
    type: 'Note',                                                                                                                                                        
    to: [                                                                                                                                                                
      'https://www.w3.org/ns/activitystreams#Public',                                                                                                                    
      'https://sopuli.xyz/u/guslipkin'                                                                                                                                   
    ],                                                                                                                                                                   
    cc: [                                                                                                                                                                
      'https://community.openbeta.io/uid/15/followers',                                                                                                                        'https://sopuli.xyz/u/guslipkin',                                                                                                                                  
      'https://aussie.zone/u/gazter'                                                                                                                                         ],                                                                                                                                                                   
    inReplyTo: 'https://sopuli.xyz/comment/13579403',                                                                                                                    
    published: '2024-12-20T17:52:51.307Z',                                                                                                                               
    updated: null,                                                                                                                                                       
    url: 'https://community.openbeta.io/post/1925',                                                                                                                      
    attributedTo: 'https://community.openbeta.io/uid/15',                                                                                                                
    context: 'https://community.openbeta.io/topic/c787dec8-fec3-4922-a542-c4b2e2c5d911',                                                                                 
    audience: 'https://community.openbeta.io/category/11',                                                                                                               
    summary: null,                                                                                                                                                       
    name: 'Re: Edelrid Ohm II vs Raed Zaed',                                                                                                                             
    content: '<p><a href="https://sopuli.xyz/u/guslipkin">@[email protected]</a> yeah the Ohmega is interesting... given how quickly it was introduced after the Ohm I
I was released.</p>\n' +                                                                                                                                                 
      "<p>It's almost like they explicitly marketed it as a different product even though it serves to replace the function of the Ohm (plus a couple added features – it
's not <em>just</em> a belay resistor)</p>\n",                                                                                                                           
    source: {                                                                                                                                                            
      content: '@[email protected] yeah the Ohmega is interesting... given how quickly it was introduced after the Ohm II was released.\n' +                          
        '\n' +                                                                                                                                                           
        "It's almost like they explicitly marketed it as a different product even though it serves to replace the function of the Ohm (plus a couple added features &ndas
h; it's not _just_ a belay resistor)",                                                                                                                                   
      mediaType: 'text/markdown'                                                                                                                                         
    },                                                                                                                                                                   
    tag: [ [Object] ],                                                                                                                                                   
    attachment: [],                                                                                                                                                      
    replies: 'https://community.openbeta.io/post/1925/replies'                                                                                                           
  }  
}

Version

BE: 0.19.8

Lemmy Instance URL

sopuli.xyz, aussie.zone

[julianlam]

I believe Lemmy is doing a check on audience and finding that it does not resolve to a known community on the local instance.

However, if a note is in reply to a valid post then the audience should be irrelevant.

Also I am assuming that simply removing audience would work, since not all implementors utilise the property.

Suggest audience property be ignored unless post is standalone?

[flamingo-cant-draw]

I believe Lemmy is doing a check on audience and finding that it does not resolve to a known community on the local instance.

Not quite, Lemmy expects the audience on a Note to match the what Lemmy determines to be the community on the Page it's a child of. Priority is given to the audience field of a Page, but if it's missing Lemmy will walk through the Page's cc and to fields and use the first it finds.