fix(ai): seed system+history via initialPrompts; let session manage state

app/scripts/background/main.js

@@ -183,6 +183,10 @@
             signal
         };
 
+        if (Array.isArray(options.initialPrompts) && options.initialPrompts.length > 0) {
+            sessionOptions.initialPrompts = options.initialPrompts;
+        }
+
         // Add download progress monitoring if callback provided
         if (options.onProgress) {
             sessionOptions.monitor = function(m) {
@@ -303,13 +307,17 @@
         }
 
         try {
-            // Destroy existing session if any
+            // Create the new session first; only swap out the old one on success.
+            // Otherwise a failure here would leave promptAPISession null and every
+            // subsequent prompt would return "No active session".
+            const newSession = await initPromptAPISession({
+                initialPrompts: data && data.initialPrompts
+            }, new AbortController().signal);
+
             if (promptAPISession) {
                 promptAPISession.destroy();
-                promptAPISession = null;
             }
-
-            promptAPISession = await initPromptAPISession({}, new AbortController().signal);
+            promptAPISession = newSession;
 
             port.postMessage({
                 type: 'session-created'
@@ -328,11 +336,10 @@
      */
     async function handlePromptStreaming(data, port) {
 
-        // Validate messages structure
-        if (!data || !Array.isArray(data.messages)) {
+        if (!data || typeof data.userMessage !== 'string') {
             port.postMessage({
                 type: 'error',
-                message: 'Invalid messages format: expected array'
+                message: 'Invalid prompt: expected userMessage string'
             });
             return;
         }
@@ -353,7 +360,7 @@
 
         try {
             const stream = await promptAPISession.promptStreaming(
-                data.messages,
+                data.userMessage,
                 { signal: promptAPIController.signal }
             );
 

app/scripts/modules/ai/AISessionManager.js

@@ -174,10 +174,11 @@ Be neutral, direct, and developer-focused. Avoid marketing language, unnecessary
 };
 
 /**
- * Create a new AI session (empty, stateless).
+ * Create a new AI session with optional initial prompts (system + history).
+ * @param {Array} initialPrompts - Optional [{role, content}, ...]; first should be 'system'.
  * @returns {Promise<boolean>} - True if session created successfully
  */
-AISessionManager.prototype.createSession = function () {
+AISessionManager.prototype.createSession = function (initialPrompts) {
     return new Promise((resolve, reject) => {
         this._connect();
 
@@ -199,7 +200,9 @@ AISessionManager.prototype.createSession = function () {
 
         this._send({
             type: 'create-session',
-            data: {}
+            data: {
+                initialPrompts: initialPrompts || []
+            }
         });
     });
 };
@@ -300,39 +303,24 @@ AISessionManager.prototype._formatPrompt = function (prompt, context) {
 };
 
 /**
- * Build messages array for prompt API.
- * @private
- * @param {string} userMessage - Current user message
- * @param {Array} conversationHistory - Previous messages [{ role, content }]
- * @param {Object} context - Optional context (control data, appInfo)
- * @returns {Array} - Messages array [{ role, content }]
+ * Build the system prompt content for a given app context.
+ * @param {Object} appInfo - Application information
+ * @returns {string}
  */
-AISessionManager.prototype._buildMessagesArray = function (userMessage, conversationHistory, context) {
-    const messages = [];
-
-    const systemPrompt = this._getDefaultSystemPrompt(context ? context.appInfo : null);
-    messages.push({ role: 'system', content: systemPrompt });
-
-    if (conversationHistory && Array.isArray(conversationHistory)) {
-        conversationHistory.forEach(msg => {
-            messages.push({ role: msg.role, content: msg.content });
-        });
-    }
-
-    const formattedMessage = this._formatPrompt(userMessage, context);
-    messages.push({ role: 'user', content: formattedMessage });
-
-    return messages;
+AISessionManager.prototype.buildSystemPrompt = function (appInfo) {
+    return this._getDefaultSystemPrompt(appInfo);
 };
 
 /**
  * Send a prompt and get a streaming response.
+ * The Chrome Prompt API session retains its own conversation history,
+ * so only the new user message is sent here. System prompt and prior
+ * turns are seeded via initialPrompts at session creation time.
  * @param {string} userMessage - Current user message
- * @param {Array} conversationHistory - Previous messages [{ role, content }]
- * @param {Object} context - Optional context (control data, appInfo)
+ * @param {Object} context - Optional context (control data) for prompt formatting
  * @returns {Promise<Object>} - Object with methods to handle streaming
  */
-AISessionManager.prototype.promptStreaming = function (userMessage, conversationHistory, context) {
+AISessionManager.prototype.promptStreaming = function (userMessage, context) {
     return new Promise((resolve, reject) => {
         this._connect();
 
@@ -341,7 +329,7 @@ AISessionManager.prototype.promptStreaming = function (userMessage, conversation
             return;
         }
 
-        const messages = this._buildMessagesArray(userMessage, conversationHistory, context);
+        const formattedMessage = this._formatPrompt(userMessage, context);
         let streamHandlers = {
             onChunk: null,
             onComplete: null,
@@ -439,11 +427,11 @@ AISessionManager.prototype.promptStreaming = function (userMessage, conversation
         this._on('complete', completeHandler);
         this._on('error', errorHandler);
 
-        // Send messages array
+        // Send only the new user message — session retains prior history.
         this._send({
             type: 'prompt-streaming',
             data: {
-                messages: messages
+                userMessage: formattedMessage
             }
         });
 

app/scripts/modules/ui/AIChat.js

@@ -20,6 +20,7 @@ function AIChat(containerId, options) {
     this._currentContext = null;
     this._messages = [];
     this._isStreaming = false;
+    this._isReseedingSession = false;
     this._streamingMessageElement = null;
     this._streamingMessageHeader = null;
     this._getAppInfo = options.getAppInfo || null;
@@ -209,12 +210,32 @@ AIChat.prototype._checkModelAvailability = async function () {
 };
 
 /**
- * Initialize AI session.
+ * Initialize AI session, seeding system prompt + any prior conversation
+ * (so the model "remembers" history loaded from storage).
  * @private
  */
 AIChat.prototype._initializeSession = async function () {
     try {
-        await this._sessionManager.createSession();
+        var appInfo = null;
+        if (this._getAppInfo) {
+            appInfo = this._getAppInfo();
+        } else if (this._currentContext) {
+            appInfo = this._currentContext.appInfo;
+        }
+
+        const initialPrompts = [
+            { role: 'system', content: this._sessionManager.buildSystemPrompt(appInfo) }
+        ];
+
+        // Replay prior user/assistant turns; skip UI-only 'system' notices
+        // and empty placeholders (e.g. the assistant slot added mid-stream).
+        this._messages.forEach(m => {
+            if ((m.role === 'user' || m.role === 'assistant') && m.content) {
+                initialPrompts.push({ role: m.role, content: m.content });
+            }
+        });
+
+        await this._sessionManager.createSession(initialPrompts);
         document.getElementById('ai-clear-history-button').style.display = 'inline-block';
         this._updateTokenCounter();
     } catch (error) {
@@ -313,9 +334,6 @@ AIChat.prototype._handleSendMessage = async function () {
         loadingIndicator.appendChild(loadingDots);
         this._streamingMessageElement.appendChild(loadingIndicator);
 
-        // Build conversation history (exclude the placeholder we just added)
-        const conversationHistory = this._messages.slice(0, -1);
-
         // Get app info for context
         var appInfo = null;
         if (this._getAppInfo) {
@@ -330,10 +348,9 @@ AIChat.prototype._handleSendMessage = async function () {
             appInfo: appInfo
         };
 
-        // Get streaming response
+        // Get streaming response — session retains history internally.
         const stream = await this._sessionManager.promptStreaming(
             userMessage,
-            conversationHistory,
             context
         );
 
@@ -1051,13 +1068,19 @@ AIChat.prototype.setUrl = function (url) {
  * @private
  */
 AIChat.prototype._loadHistory = async function () {
+    if (this._isStreaming || this._isReseedingSession) {
+        return;
+    }
     try {
         const messages = await this._storageManager.loadHistory(this._currentUrl);
 
-        if (messages.length > 0) {
-            const messagesContainer = document.getElementById('ai-messages-container');
-            messagesContainer.innerHTML = '';
+        // Reset in-memory state before repopulating from storage —
+        // _addMessage always pushes, so without this every tab switch duplicates.
+        this._messages = [];
+        const messagesContainer = document.getElementById('ai-messages-container');
+        messagesContainer.innerHTML = '';
 
+        if (messages.length > 0) {
             messages.forEach(msg => {
                 this._addMessage(msg.role, msg.content);
             });
@@ -1066,7 +1089,20 @@ AIChat.prototype._loadHistory = async function () {
             // Force scroll to bottom when loading history
             this._scrollToBottom(true);
         }
+
+        // Re-seed session regardless of history length: a fresh app context
+        // (different framework version, theme, libraries) needs a new system prompt.
+        if (this._sessionManager.hasActiveSession()) {
+            this._isReseedingSession = true;
+            try {
+                this._sessionManager.destroy();
+                await this._initializeSession();
+            } finally {
+                this._isReseedingSession = false;
+            }
+        }
     } catch (error) {
+        this._isReseedingSession = false;
         // Fail silently
     }
 };

tests/modules/ai/AISessionManager.spec.js

@@ -184,46 +184,23 @@ describe('AISessionManager', function () {
         });
     });
 
-    describe('#_buildMessagesArray()', function () {
-        it('should include system prompt', function () {
-            var messages = sessionManager._buildMessagesArray('Hello', [], null);
+    describe('#buildSystemPrompt()', function () {
+        it('should return the default system prompt', function () {
+            var prompt = sessionManager.buildSystemPrompt(null);
 
-            messages[0].role.should.equal('system');
-            messages[0].content.should.contain('AI assistant');
-        });
-
-        it('should include conversation history', function () {
-            var history = [
-                { role: 'user', content: 'First question' },
-                { role: 'assistant', content: 'First answer' }
-            ];
-
-            var messages = sessionManager._buildMessagesArray('Second question', history, null);
-
-            messages.should.have.lengthOf(4);
-            messages[1].content.should.equal('First question');
-            messages[2].content.should.equal('First answer');
+            prompt.should.contain('AI assistant');
         });
 
-        it('should format user message with context', function () {
-            var context = {
-                control: {
-                    type: 'sap.m.Button',
-                    id: 'btn1'
-                }
+        it('should include app context when appInfo provided', function () {
+            var appInfo = {
+                common: { data: { OpenUI5: '1.120.0' } },
+                configurationComputed: { data: { theme: 'sap_horizon' } }
             };
 
-            var messages = sessionManager._buildMessagesArray('What is this?', [], context);
-
-            messages[1].role.should.equal('user');
-            messages[1].content.should.contain('Type: sap.m.Button');
-            messages[1].content.should.contain('What is this?');
-        });
-
-        it('should handle empty conversation history', function () {
-            var messages = sessionManager._buildMessagesArray('Hello', null, null);
+            var prompt = sessionManager.buildSystemPrompt(appInfo);
 
-            messages.should.have.lengthOf(2);
+            prompt.should.contain('1.120.0');
+            prompt.should.contain('sap_horizon');
         });
     });