fix: restore generic inline document endpoint fallbacks

src/server/proxy-core/capabilities/conversationFileCapabilities.test.ts

@@ -67,7 +67,7 @@ describe('conversationFileCapabilities', () => {
     })).toMatchObject({
       image: 'native',
       audio: 'unsupported',
-      document: 'unsupported',
+      document: 'inline_only',
       preservesRemoteDocumentUrl: false,
     });
   });
@@ -84,6 +84,6 @@ describe('conversationFileCapabilities', () => {
       },
     });
 
-    expect(ranked).toEqual(['responses', 'chat']);
+    expect(ranked).toEqual(['responses', 'messages', 'chat']);
   });
 });

src/server/proxy-core/capabilities/conversationFileCapabilities.ts

@@ -218,7 +218,7 @@ export function resolveConversationFileEndpointCapability(input: {
     return {
       image: 'native',
       audio: 'unsupported',
-      document: 'unsupported',
+      document: 'inline_only',
       preservesRemoteDocumentUrl: false,
     };
   }
@@ -261,7 +261,7 @@ export function rankConversationFileEndpoints(input: {
   }) as ConversationFileEndpoint[];
 
   if (supportedDocumentEndpoints.length <= 0) {
-    return [];
+    return [...input.requestedOrder];
   }
 
   return [

src/server/routes/proxy/upstreamEndpoint.test.ts

@@ -193,7 +193,7 @@ describe('resolveUpstreamEndpointCandidates', () => {
       },
     );
 
-    expect(order).toEqual(['responses', 'chat']);
+    expect(order).toEqual(['responses', 'messages', 'chat']);
   });
 
   it('remembers the last successful endpoint per site capability profile', async () => {