Fix critical bugs: document duplication, stop button, and session discovery

Backend fixes:
- Improve AI prompt with CRITICAL RULES emphasizing single section only
- Add examples of CORRECT vs INCORRECT responses
- Fix extractSection() to validate extracted content
- Validate sections are < 5KB and start with markdown headers
- Return error indicator for invalid section formats
- This prevents IAs from returning entire document

Frontend fixes:
- Fix stop button: call ws.disconnect() to close WebSocket immediately
- Stop processing WebSocket messages when isStopping is true
- Clear messageInterval when stopping
- Add archive sessions section on home page for easy access
- Display all sessions in a searchable grid format
- Add session status indicators and date
- Scrollable grid for browsing all sessions
- Integrated with existing search functionality

User experience improvements:
- Sessions now accessible both at top (Quick Access) and bottom (Archive)
- Unified search works across all filtering
- Stop button now truly stops the session
- Better validation prevents document duplication bug

backend/src/services/mistralClient.js

@@ -20,10 +20,11 @@ Your responsibilities:
 3. Provide your thinking process and reasoning
 4. Return ONLY the section (modified or new) with its header, or command to delete, or confirm it's good as-is
 
-IMPORTANT RULES:
+CRITICAL RULES - FOLLOW THESE EXACTLY:
 - Work on exactly ONE section only
-- Never modify the entire document
+- NEVER return the entire document
-- Return only the section you're working on, not the whole document
+- NEVER return multiple sections
+- Return ONLY the section you're working on, not the whole document
 - You CAN create a new section if document is missing important content
 - You CAN delete a section if it's redundant, duplicate, or not useful
 - To delete a section, respond: "DELETE: ## Section Name" (with exact header)
@@ -31,11 +32,21 @@ IMPORTANT RULES:
 - Think step-by-step about what could be improved or removed
 - Share your reasoning process
 
-Format your response as:
+RESPONSE FORMAT - FOLLOW THIS EXACTLY:
-THINKING: [Your analysis and reasoning]
+THINKING: [Your analysis and reasoning about the current document]
-DECISION: [What you'll modify, create, delete, or if keeping as-is]
+DECISION: [Exactly what you will do: modify section X, create new section Y, delete section Z, or keep as-is]
 SECTION:
-[The modified section, new section, DELETE command, or confirmation that all is good]`
+[ONLY ONE: Either a markdown section starting with # or ##, a DELETE command, or the text "Section is good, no changes needed"]
+
+EXAMPLE OF CORRECT RESPONSE:
+THINKING: The Overview section is too brief and doesn't explain the main purpose.
+DECISION: I will modify the Overview section to be more comprehensive.
+SECTION:
+## Overview
+This is a technical document for designing system architecture...
+
+EXAMPLE OF INCORRECT RESPONSE (DO NOT DO THIS):
+[The entire document repeated here] <- WRONG!`
 }
 
 /**
@@ -102,13 +113,32 @@ export async function generateAgentResponseSync(agentName, prompt, currentDocume
 
 /**
  * Extract section from AI response
+ * Validates that we get a proper section, not the entire document
  */
 export function extractSection(aiResponse) {
-  const sectionMatch = aiResponse.match(/SECTION:\s*([\s\S]*?)(?:$|THINKING:|DECISION:)/)
+  const sectionMatch = aiResponse.match(/SECTION:\s*([\s\S]*?)(?:$)/)
   if (sectionMatch) {
-    return sectionMatch[1].trim()
+    const extracted = sectionMatch[1].trim()
+
+    // Validate: extracted should be either:
+    // 1. A markdown section starting with # (DELETE: or "Section is good...")
+    // 2. OR a single section with < 5000 chars (not entire document)
+    const isMarkdownSection = /^(#|DELETE:|Section is good)/.test(extracted)
+    const isShortEnough = extracted.length < 5000 // Single section should be < 5KB
+
+    if (isMarkdownSection || isShortEnough) {
+      return extracted
+    }
   }
-  return aiResponse
+
+  // Fallback: if no SECTION: tag found, treat entire response as section
+  // but only if it starts with markdown header or is a command
+  if (/^(#|DELETE:|Section is good)/.test(aiResponse)) {
+    return aiResponse.trim()
+  }
+
+  // If none of the above, return error indicator
+  return "ERROR: Response does not contain a valid section format"
 }
 
 /**

frontend/src/components/CollaborativeInput.vue

@@ -327,6 +327,46 @@ const removeFile = () => {
         </button>
       </form>
 
+      <!-- All Sessions Archive -->
+      <div class="sessions-archive-section">
+        <h2>📚 All Sessions Archive</h2>
+        <p class="archive-subtitle">Browse and access all previous sessions</p>
+
+        <!-- Archive Filter -->
+        <div class="archive-filter">
+          <input
+            v-model="searchQuery"
+            type="text"
+            placeholder="Search sessions..."
+            class="archive-search"
+          />
+        </div>
+
+        <!-- Archive Sessions -->
+        <div v-if="filteredSessions.length > 0" class="archive-sessions">
+          <div class="sessions-list">
+            <div
+              v-for="session in filteredSessions"
+              :key="session.sessionId"
+              @click="handleOpenSession(session.sessionId)"
+              class="archive-session-item"
+              :class="'status-' + session.status"
+            >
+              <div class="archive-item-header">
+                <span class="session-number">#{{ session.sessionId }}</span>
+                <span class="session-status-badge">{{ session.status }}</span>
+              </div>
+              <p class="archive-item-prompt">{{ session.prompt.substring(0, 120) }}...</p>
+              <p class="archive-item-date">{{ new Date(session.createdAt).toLocaleDateString() }}</p>
+            </div>
+          </div>
+        </div>
+
+        <div v-else class="no-sessions">
+          <p>No sessions found</p>
+        </div>
+      </div>
+
       <footer class="footer">
         <p>Typical session: 2-5 rounds for complete consensus. Output format: Markdown</p>
       </footer>
@@ -968,6 +1008,142 @@ const removeFile = () => {
   z-index: 0;
 }
 
+/* Sessions Archive Section */
+.sessions-archive-section {
+  margin: 3rem 0 2rem 0;
+  padding: 2rem;
+  background: rgba(102, 126, 234, 0.05);
+  border: 1px solid rgba(102, 126, 234, 0.2);
+  border-radius: 16px;
+  backdrop-filter: blur(10px);
+}
+
+.sessions-archive-section h2 {
+  margin: 0 0 0.5rem 0;
+  font-size: 1.5rem;
+  color: rgba(255, 255, 255, 0.95);
+  font-weight: 700;
+}
+
+.archive-subtitle {
+  margin: 0 0 1.5rem 0;
+  color: rgba(255, 255, 255, 0.6);
+  font-size: 0.95rem;
+}
+
+.archive-filter {
+  margin-bottom: 1.5rem;
+}
+
+.archive-search {
+  width: 100%;
+  padding: 0.75rem 1rem;
+  background: rgba(255, 255, 255, 0.07);
+  border: 1px solid rgba(102, 126, 234, 0.3);
+  color: rgba(255, 255, 255, 0.9);
+  border-radius: 8px;
+  font-size: 0.95rem;
+  transition: all 0.3s ease;
+}
+
+.archive-search::placeholder {
+  color: rgba(255, 255, 255, 0.4);
+}
+
+.archive-search:focus {
+  outline: none;
+  border-color: rgba(102, 126, 234, 0.6);
+  background: rgba(102, 126, 234, 0.1);
+}
+
+.sessions-list {
+  display: grid;
+  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
+  gap: 1rem;
+  max-height: 500px;
+  overflow-y: auto;
+}
+
+.archive-session-item {
+  padding: 1rem;
+  background: rgba(255, 255, 255, 0.05);
+  border: 1px solid rgba(102, 126, 234, 0.2);
+  border-radius: 12px;
+  cursor: pointer;
+  transition: all 0.3s ease;
+  display: flex;
+  flex-direction: column;
+  gap: 0.75rem;
+}
+
+.archive-session-item:hover {
+  background: rgba(102, 126, 234, 0.15);
+  border-color: rgba(102, 126, 234, 0.4);
+  transform: translateY(-2px);
+  box-shadow: 0 8px 20px rgba(102, 126, 234, 0.15);
+}
+
+.archive-session-item.status-completed {
+  border-color: rgba(76, 175, 80, 0.3);
+  background: rgba(76, 175, 80, 0.05);
+}
+
+.archive-session-item.status-completed:hover {
+  background: rgba(76, 175, 80, 0.12);
+  border-color: rgba(76, 175, 80, 0.5);
+  box-shadow: 0 8px 20px rgba(76, 175, 80, 0.15);
+}
+
+.archive-item-header {
+  display: flex;
+  justify-content: space-between;
+  align-items: center;
+}
+
+.session-number {
+  color: rgba(102, 126, 234, 0.9);
+  font-weight: 700;
+  font-size: 0.95rem;
+}
+
+.session-status-badge {
+  padding: 0.3rem 0.7rem;
+  background: rgba(102, 126, 234, 0.2);
+  color: rgba(102, 126, 234, 0.9);
+  border-radius: 20px;
+  font-size: 0.75rem;
+  font-weight: 600;
+  text-transform: capitalize;
+}
+
+.archive-session-item.status-completed .session-status-badge {
+  background: rgba(76, 175, 80, 0.2);
+  color: rgba(76, 175, 80, 0.9);
+}
+
+.archive-item-prompt {
+  margin: 0;
+  color: rgba(255, 255, 255, 0.8);
+  font-size: 0.9rem;
+  line-height: 1.4;
+  display: -webkit-box;
+  -webkit-line-clamp: 2;
+  -webkit-box-orient: vertical;
+  overflow: hidden;
+}
+
+.archive-item-date {
+  margin: 0;
+  color: rgba(255, 255, 255, 0.4);
+  font-size: 0.8rem;
+}
+
+.no-sessions {
+  text-align: center;
+  padding: 2rem 1rem;
+  color: rgba(255, 255, 255, 0.5);
+}
+
 @media (max-width: 768px) {
   .collaborative-input {
     padding: 1rem;

frontend/src/components/CollaborativeSession.vue

@@ -52,6 +52,11 @@ onMounted(async () => {
     ws.connect()
 
     const messageInterval = setInterval(() => {
+      // Stop processing messages if session is stopped
+      if (isStopping.value) {
+        clearInterval(messageInterval)
+        return
+      }
       if (ws.messages.value.length > 0) {
         const message = ws.messages.value.shift()
         handleWebSocketMessage(message)
@@ -159,6 +164,9 @@ const stopSession = async () => {
   isStopping.value = true
   isAutoRunning.value = false
   if (autoRunTimeout.value) clearTimeout(autoRunTimeout.value)
+  // Close WebSocket connection immediately
+  ws.disconnect()
+  // Then complete the session on backend
   await completeSession()
 }