[FEATURE]: Expose the ability to modify the chat messages thread via a plugin #7034

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1. NikhilVerma

   added

   discussionUsed for feature requests, proposals, ideas, etc. Open discussionUsed for feature requests, proposals, ideas, etc. Open discussion

   on Jan 6, 2026
2. github-actions commented on Jan 6, 2026

   

   github-actionsBot

   on Jan 6, 2026 – with GitHub Actions

   Contributor

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   This issue might be a duplicate of existing issues. Please check:

   • [FEATURE] Sliding window context management for long-running sessions #4659: [FEATURE] Sliding window context management for long-running sessions - discusses preserving and managing message context with compression/compaction mechanisms
   • /undo command only rolls back AI conversation message, not the associated file changes #5474: /undo command only rolls back AI conversation message, not the associated file changes - related to reverting conversation state
   • [FEATURE]: Delayed queue feature #5408: [FEATURE]: Delayed queue feature - discusses queuing messages and controlling chat flow for long-running agents
   • Feature Request: Add redoable parameter to control permanent message deletion after revert #4681: Feature Request: Add redoable parameter to control permanent message deletion after revert - relates to message state management

   Feel free to ignore if none of these address your specific case.
3. github-actions

   assigned

   thdxr

   on Jan 6, 2026
4. Wuchv commented on Jan 23, 2026

   

   Wuchv

   on Jan 23, 2026

   More actions

   I have the same requirement. my case is that a large model needs to understand an image based on a URL.

   The prompt is as follows:
   https://xxxxx/xxx.png please describe this image.

   Opencode interprets the request to the large model as a text:

   "messages": [
       {
         "role": "user",
         "content": [
           {
             "type": "text",
             "text": "https://xxxxx/xxx.png please describe this image",
           }
         ]

   but the format required for large models is as follows:

       "messages": [
           {
               "role": "user",
               "content":
               [
                   {
                       "type": "image_url",
                      "image_url": "https://xxxxx/xxx.png"
                   },
                   {
                       "type": "text",
                       "text": "please describe this image"
                   }
               ]
           }
       ]

   I need a hook that can modify messages before making a request to the large model.
5. Wuchv commented on Jan 23, 2026

   

   Wuchv

   on Jan 23, 2026

   More actions

   I have the same requirement. my case is that a large model needs to understand an image based on a URL.

   The prompt is as follows: https://xxxxx/xxx.png please describe this image.

   Opencode interprets the request to the large model as a text:

   "messages": [
   {
   "role": "user",
   "content": [
   {
   "type": "text",
   "text": "https://xxxxx/xxx.png please describe this image",
   }
   ]
   but the format required for large models is as follows:

   "messages": [
       {
           "role": "user",
           "content":
           [
               {
                   "type": "image_url",
                  "image_url": "https://xxxxx/xxx.png"
               },
               {
                   "type": "text",
                   "text": "please describe this image"
               }
           ]
       }
   ]
   

   I need a hook that can modify messages before making a request to the large model.

   https://github.com/anomalyco/opencode/blob/dev/packages/opencode/src/session/prompt.ts#L594

   I looked at the code of OpenCode and found that it now supports modifying messages. Here is a demo:

   export const MessagePlugin: Plugin = async (
     input: PluginInput,
   ): Promise<Hooks> => {
     const client = input.client;
   
     return {
       'experimental.chat.messages.transform': async (hookInput, output) => {
         for (const message of output.messages) {
           if (message.info.role !== 'user')
             return;
   
           const newParts: Part[] = [];
   
           await client.app.log({
             body: {
               service: 'message-plugin',
               level: 'info',
               message: 'user message',
               extra: {
                 message,
               },
             },
           });
   
           for (const part of message.parts) {
             if (part.type === 'text') {
               // ...
               newParts.push(part);
           }
   
           if (newParts.length !== message.parts.length) {
             message.parts = newParts;
           }
         }
       },
     };
   };
6. github-actions commented on Mar 26, 2026

   

   github-actionsBot

   on Mar 26, 2026 – with GitHub Actions

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   To stay organized issues are automatically closed after 90 days of no activity. If the issue is still relevant please open a new one.

   👎React with 👎2Reacted by Benoit de Chezelles and Staltux
7. github-actions

   closed this as completedon Mar 26, 2026