From 59ba22fa9e5cb1c0a9f58935408017d0bf05a52c Mon Sep 17 00:00:00 2001
From: Cohee <18619528+Cohee1207@users.noreply.github.com>
Date: Fri, 28 Nov 2025 17:21:12 +0200
Subject: [PATCH] "Squash system messages" is back

---
 default/content/presets/openai/Default.json |  1 +
 default/content/settings.json               |  4 +-
 public/index.html                           | 13 ++++++
 public/scripts/openai.js                    | 51 +++++++++++++++++++++
 4 files changed, 68 insertions(+), 1 deletion(-)

diff --git a/default/content/presets/openai/Default.json b/default/content/presets/openai/Default.json
index c4e097984..428bbda19 100644
--- a/default/content/presets/openai/Default.json
+++ b/default/content/presets/openai/Default.json
@@ -231,6 +231,7 @@
     "assistant_prefill": "",
     "assistant_impersonation": "",
     "use_sysprompt": false,
+    "squash_system_messages": false,
     "media_inlining": true,
     "bypass_status_check": false,
     "continue_prefill": false,
diff --git a/default/content/settings.json b/default/content/settings.json
index 1e712af51..7c2e4279b 100644
--- a/default/content/settings.json
+++ b/default/content/settings.json
@@ -631,6 +631,8 @@
         "show_external_models": false,
         "proxy_password": "",
         "assistant_prefill": "",
-        "assistant_impersonation": ""
+        "assistant_impersonation": "",
+        "use_sysprompt": false,
+        "squash_system_messages": false
     }
 }
diff --git a/public/index.html b/public/index.html
index c0d20263d..6177d05ea 100644
--- a/public/index.html
+++ b/public/index.html
@@ -1930,6 +1930,19 @@
                                             </span>
                                         </div>
                                     </div>
+                                    <div class="range-block">
+                                        <label for="squash_system_messages" title="Squash system messages" data-i18n="[title]Squash system messages" class="checkbox_label widthFreeExpand">
+                                            <input id="squash_system_messages" type="checkbox" />
+                                            <span data-i18n="Squash system messages">
+                                                Squash system messages
+                                            </span>
+                                        </label>
+                                        <div class="toggle-description justifyLeft">
+                                            <span data-i18n="Combines consecutive system messages into one (excluding example dialogues). May improve coherence for some models.">
+                                                Combines consecutive system messages into one (excluding example dialogues). May improve coherence for some models.
+                                            </span>
+                                        </div>
+                                    </div>
                                     <div class="range-block" data-source="claude,makersuite,vertexai">
                                         <label for="use_sysprompt" class="checkbox_label widthFreeExpand">
                                             <input id="use_sysprompt" type="checkbox" />
diff --git a/public/scripts/openai.js b/public/scripts/openai.js
index a068544f7..c2bf7ab62 100644
--- a/public/scripts/openai.js
+++ b/public/scripts/openai.js
@@ -334,6 +334,7 @@ export const settingsToUpdate = {
     vertexai_auth_mode: ['#vertexai_auth_mode', 'vertexai_auth_mode', false, true],
     vertexai_region: ['#vertexai_region', 'vertexai_region', false, true],
     vertexai_express_project_id: ['#vertexai_express_project_id', 'vertexai_express_project_id', false, true],
+    squash_system_messages: ['#squash_system_messages', 'squash_system_messages', true, false],
     media_inlining: ['#openai_media_inlining', 'media_inlining', true, false],
     inline_image_quality: ['#openai_inline_image_quality', 'inline_image_quality', false, false],
     continue_prefill: ['#continue_prefill', 'continue_prefill', true, false],
@@ -430,6 +431,7 @@ const default_settings = {
     vertexai_auth_mode: 'express',
     vertexai_region: 'us-central1',
     vertexai_express_project_id: '',
+    squash_system_messages: false,
     media_inlining: true,
     inline_image_quality: 'auto',
     bypass_status_check: false,
@@ -1448,6 +1450,10 @@ export async function prepareOpenAIMessages({
         // Pass chat completion to prompt manager for inspection
         promptManager.setChatCompletion(chatCompletion);
 
+        if (oai_settings.squash_system_messages && dryRun == false) {
+            await chatCompletion.squashSystemMessages();
+        }
+
         // All information is up-to-date, render.
         if (false === dryRun) promptManager.render(false);
     }
@@ -3274,6 +3280,46 @@ class MessageCollection {
  *
  */
 export class ChatCompletion {
+    /**
+     * Combines consecutive system messages into one if they have no name attached.
+     * @returns {Promise<void>}
+     */
+    async squashSystemMessages() {
+        const excludeList = ['newMainChat', 'newChat', 'groupNudge'];
+        this.messages.collection = this.messages.flatten();
+
+        let lastMessage = null;
+        let squashedMessages = [];
+
+        for (let message of this.messages.collection) {
+            // Force exclude empty messages
+            if (message.role === 'system' && !message.content) {
+                continue;
+            }
+
+            const shouldSquash = (message) => {
+                return !excludeList.includes(message.identifier) && message.role === 'system' && !message.name;
+            };
+
+            if (shouldSquash(message)) {
+                if (lastMessage && shouldSquash(lastMessage)) {
+                    lastMessage.content += '\n' + message.content;
+                    lastMessage.tokens = await tokenHandler.countAsync({ role: lastMessage.role, content: lastMessage.content });
+                }
+                else {
+                    squashedMessages.push(message);
+                    lastMessage = message;
+                }
+            }
+            else {
+                squashedMessages.push(message);
+                lastMessage = message;
+            }
+        }
+
+        this.messages.collection = squashedMessages;
+    }
+
     /**
      * Initializes a new instance of ChatCompletion.
      * Sets up the initial token budget and a new message collection.
@@ -6112,6 +6158,11 @@ export function initOpenAI() {
         saveSettingsDebounced();
     });
 
+    $('#squash_system_messages').on('input', function () {
+        oai_settings.squash_system_messages = !!$(this).prop('checked');
+        saveSettingsDebounced();
+    });
+
     $('#openai_media_inlining').on('input', function () {
         oai_settings.media_inlining = !!$(this).prop('checked');
         updateFeatureSupportFlags();