(function() {
      'use strict';

      // ============================================================
      // DATA LOADING
      // ============================================================

      const base64 = document.getElementById('session-data').textContent;
      const binary = atob(base64);
      const bytes = new Uint8Array(binary.length);
      for (let i = 0; i < binary.length; i++) {
        bytes[i] = binary.charCodeAt(i);
      }
      const data = JSON.parse(new TextDecoder('utf-8').decode(bytes));
      const { header, entries, leafId: defaultLeafId, systemPrompt, tools, renderedTools } = data;

      // ============================================================
      // URL PARAMETER HANDLING
      // ============================================================

      // Parse URL parameters for deep linking: leafId and targetId
      // Check for injected params (when loaded in iframe via srcdoc) or use window.location
      const injectedParams = document.querySelector('meta[name="pi-url-params"]');
      const searchString = injectedParams ? injectedParams.content : window.location.search.substring(1);
      const urlParams = new URLSearchParams(searchString);
      const urlLeafId = urlParams.get('leafId');
      const urlTargetId = urlParams.get('targetId');
      // Use URL leafId if provided, otherwise fall back to session default
      const leafId = urlLeafId || defaultLeafId;

      // ============================================================
      // DATA STRUCTURES
      // ============================================================

      // Entry lookup by ID
      const byId = new Map();
      for (const entry of entries) {
        byId.set(entry.id, entry);
      }

      // Tool call lookup (toolCallId -> {name, arguments})
      const toolCallMap = new Map();
      for (const entry of entries) {
        if (entry.type === 'message' && entry.message.role === 'assistant') {
          const content = entry.message.content;
          if (Array.isArray(content)) {
            for (const block of content) {
              if (block.type === 'toolCall') {
                toolCallMap.set(block.id, { name: block.name, arguments: block.arguments });
              }
            }
          }
        }
      }

      // Label lookup (entryId -> label string)
      // Labels are stored in 'label' entries that reference their target via targetId
      const labelMap = new Map();
      for (const entry of entries) {
        if (entry.type === 'label' && entry.targetId && entry.label) {
          labelMap.set(entry.targetId, entry.label);
        }
      }

      // ============================================================
      // TREE DATA PREPARATION (no DOM, pure data)
      // ============================================================

      /**
       * Build tree structure from flat entries.
       * Returns array of root nodes, each with { entry, children, label }.
       */
      function buildTree() {
        const nodeMap = new Map();
        const roots = [];

        // Create nodes
        for (const entry of entries) {
          nodeMap.set(entry.id, { 
            entry, 
            children: [],
            label: labelMap.get(entry.id)
          });
        }

        // Build parent-child relationships
        for (const entry of entries) {
          const node = nodeMap.get(entry.id);
          if (entry.parentId === null || entry.parentId === undefined || entry.parentId === entry.id) {
            roots.push(node);
          } else {
            const parent = nodeMap.get(entry.parentId);
            if (parent) {
              parent.children.push(node);
            } else {
              roots.push(node);
            }
          }
        }

        // Sort children by timestamp
        function sortChildren(node) {
          node.children.sort((a, b) =>
            new Date(a.entry.timestamp).getTime() - new Date(b.entry.timestamp).getTime()
          );
          node.children.forEach(sortChildren);
        }
        roots.forEach(sortChildren);

        return roots;
      }

      /**
       * Build set of entry IDs on path from root to target.
       */
      function buildActivePathIds(targetId) {
        const ids = new Set();
        let current = byId.get(targetId);
        while (current) {
          ids.add(current.id);
          // Stop if no parent or self-referencing (root)
          if (!current.parentId || current.parentId === current.id) {
            break;
          }
          current = byId.get(current.parentId);
        }
        return ids;
      }

      /**
       * Get array of entries from root to target (the conversation path).
       */
      function getPath(targetId) {
        const path = [];
        let current = byId.get(targetId);
        while (current) {
          path.unshift(current);
          // Stop if no parent or self-referencing (root)
          if (!current.parentId || current.parentId === current.id) {
            break;
          }
          current = byId.get(current.parentId);
        }
        return path;
      }

      // Tree node lookup for finding leaves
      let treeNodeMap = null;

      /**
       * Find the newest leaf node reachable from a given node.
       * This allows clicking any node in a branch to show the full branch.
       * Children are sorted by timestamp, so the newest is always last.
       */
      function findNewestLeaf(nodeId) {
        // Build tree node map lazily
        if (!treeNodeMap) {
          treeNodeMap = new Map();
          const tree = buildTree();
          function mapNodes(node) {
            treeNodeMap.set(node.entry.id, node);
            node.children.forEach(mapNodes);
          }
          tree.forEach(mapNodes);
        }

        const node = treeNodeMap.get(nodeId);
        if (!node) return nodeId;

        // Follow the newest (last) child at each level
        let current = node;
        while (current.children.length > 0) {
          current = current.children[current.children.length - 1];
        }
        return current.entry.id;
      }

      /**
       * Flatten tree into list with indentation and connector info.
       * Returns array of { node, indent, showConnector, isLast, gutters, isVirtualRootChild, multipleRoots }.
       * Matches tree-selector.ts logic exactly.
       */
      function flattenTree(roots, activePathIds) {
        const result = [];
        const multipleRoots = roots.length > 1;

        // Mark which subtrees contain the active leaf
        const containsActive = new Map();
        function markActive(node) {
          let has = activePathIds.has(node.entry.id);
          for (const child of node.children) {
            if (markActive(child)) has = true;
          }
          containsActive.set(node, has);
          return has;
        }
        roots.forEach(markActive);

        // Stack: [node, indent, justBranched, showConnector, isLast, gutters, isVirtualRootChild]
        const stack = [];

        // Add roots (prioritize branch containing active leaf)
        const orderedRoots = [...roots].sort((a, b) => 
          Number(containsActive.get(b)) - Number(containsActive.get(a))
        );
        for (let i = orderedRoots.length - 1; i >= 0; i--) {
          const isLast = i === orderedRoots.length - 1;
          stack.push([orderedRoots[i], multipleRoots ? 1 : 0, multipleRoots, multipleRoots, isLast, [], multipleRoots]);
        }

        while (stack.length > 0) {
          const [node, indent, justBranched, showConnector, isLast, gutters, isVirtualRootChild] = stack.pop();

          result.push({ node, indent, showConnector, isLast, gutters, isVirtualRootChild, multipleRoots });

          const children = node.children;
          const multipleChildren = children.length > 1;

          // Order children (active branch first)
          const orderedChildren = [...children].sort((a, b) => 
            Number(containsActive.get(b)) - Number(containsActive.get(a))
          );

          // Calculate child indent (matches tree-selector.ts)
          let childIndent;
          if (multipleChildren) {
            // Parent branches: children get +1
            childIndent = indent + 1;
          } else if (justBranched && indent > 0) {
            // First generation after a branch: +1 for visual grouping
            childIndent = indent + 1;
          } else {
            // Single-child chain: stay flat
            childIndent = indent;
          }

          // Build gutters for children
          const connectorDisplayed = showConnector && !isVirtualRootChild;
          const currentDisplayIndent = multipleRoots ? Math.max(0, indent - 1) : indent;
          const connectorPosition = Math.max(0, currentDisplayIndent - 1);
          const childGutters = connectorDisplayed
            ? [...gutters, { position: connectorPosition, show: !isLast }]
            : gutters;

          // Add children in reverse order for stack
          for (let i = orderedChildren.length - 1; i >= 0; i--) {
            const childIsLast = i === orderedChildren.length - 1;
            stack.push([orderedChildren[i], childIndent, multipleChildren, multipleChildren, childIsLast, childGutters, false]);
          }
        }

        return result;
      }

      /**
       * Build ASCII prefix string for tree node.
       */
      function buildTreePrefix(flatNode) {
        const { indent, showConnector, isLast, gutters, isVirtualRootChild, multipleRoots } = flatNode;
        const displayIndent = multipleRoots ? Math.max(0, indent - 1) : indent;
        const connector = showConnector && !isVirtualRootChild ? (isLast ? '└─ ' : '├─ ') : '';
        const connectorPosition = connector ? displayIndent - 1 : -1;

        const totalChars = displayIndent * 3;
        const prefixChars = [];
        for (let i = 0; i < totalChars; i++) {
          const level = Math.floor(i / 3);
          const posInLevel = i % 3;

          const gutter = gutters.find(g => g.position === level);
          if (gutter) {
            prefixChars.push(posInLevel === 0 ? (gutter.show ? '│' : ' ') : ' ');
          } else if (connector && level === connectorPosition) {
            if (posInLevel === 0) {
              prefixChars.push(isLast ? '└' : '├');
            } else if (posInLevel === 1) {
              prefixChars.push('─');
            } else {
              prefixChars.push(' ');
            }
          } else {
            prefixChars.push(' ');
          }
        }
        return prefixChars.join('');
      }

      // ============================================================
      // FILTERING (pure data)
      // ============================================================

      let filterMode = 'default';
      let searchQuery = '';

      function hasTextContent(content) {
        if (typeof content === 'string') return content.trim().length > 0;
        if (Array.isArray(content)) {
          for (const c of content) {
            if (c.type === 'text' && c.text && c.text.trim().length > 0) return true;
          }
        }
        return false;
      }

      function extractContent(content) {
        if (typeof content === 'string') return content;
        if (Array.isArray(content)) {
          return content
            .filter(c => c.type === 'text' && c.text)
            .map(c => c.text)
            .join('');
        }
        return '';
      }

      function getSearchableText(entry, label) {
        const parts = [];
        if (label) parts.push(label);

        switch (entry.type) {
          case 'message': {
            const msg = entry.message;
            parts.push(msg.role);
            if (msg.content) parts.push(extractContent(msg.content));
            if (msg.role === 'bashExecution' && msg.command) parts.push(msg.command);
            break;
          }
          case 'custom_message':
            parts.push(entry.customType);
            parts.push(typeof entry.content === 'string' ? entry.content : extractContent(entry.content));
            break;
          case 'compaction':
            parts.push('compaction');
            break;
          case 'branch_summary':
            parts.push('branch summary', entry.summary);
            break;
          case 'model_change':
            parts.push('model', entry.modelId);
            break;
          case 'thinking_level_change':
            parts.push('thinking', entry.thinkingLevel);
            break;
        }

        return parts.join(' ').toLowerCase();
      }

      /**
       * Filter flat nodes based on current filterMode and searchQuery.
       */
      function filterNodes(flatNodes, currentLeafId) {
        const searchTokens = searchQuery.toLowerCase().split(/\s+/).filter(Boolean);

        const filtered = flatNodes.filter(flatNode => {
          const entry = flatNode.node.entry;
          const label = flatNode.node.label;
          const isCurrentLeaf = entry.id === currentLeafId;

          // Always show current leaf
          if (isCurrentLeaf) return true;

          // Hide assistant messages with only tool calls (no text) unless error/aborted
          if (entry.type === 'message' && entry.message.role === 'assistant') {
            const msg = entry.message;
            const hasText = hasTextContent(msg.content);
            const isErrorOrAborted = msg.stopReason && msg.stopReason !== 'stop' && msg.stopReason !== 'toolUse';
            if (!hasText && !isErrorOrAborted) return false;
          }

          // Apply filter mode
          const isSettingsEntry = ['label', 'custom', 'model_change', 'thinking_level_change'].includes(entry.type);
          let passesFilter = true;

          switch (filterMode) {
            case 'user-only':
              passesFilter = entry.type === 'message' && entry.message.role === 'user';
              break;
            case 'no-tools':
              passesFilter = !isSettingsEntry && !(entry.type === 'message' && entry.message.role === 'toolResult');
              break;
            case 'labeled-only':
              passesFilter = label !== undefined;
              break;
            case 'all':
              passesFilter = true;
              break;
            default: // 'default'
              passesFilter = !isSettingsEntry;
              break;
          }

          if (!passesFilter) return false;

          // Apply search filter
          if (searchTokens.length > 0) {
            const nodeText = getSearchableText(entry, label);
            if (!searchTokens.every(t => nodeText.includes(t))) return false;
          }

          return true;
        });

        // Recalculate visual structure based on visible tree
        recalculateVisualStructure(filtered, flatNodes);

        return filtered;
      }

      /**
       * Recompute indentation/connectors for the filtered view
       *
       * Filtering can hide intermediate entries; descendants attach to the nearest visible ancestor.
       * Keep indentation semantics aligned with flattenTree() so single-child chains don't drift right.
       */
      function recalculateVisualStructure(filteredNodes, allFlatNodes) {
        if (filteredNodes.length === 0) return;

        const visibleIds = new Set(filteredNodes.map(n => n.node.entry.id));

        // Build entry map for parent lookup (using full tree)
        const entryMap = new Map();
        for (const flatNode of allFlatNodes) {
          entryMap.set(flatNode.node.entry.id, flatNode);
        }

        // Find nearest visible ancestor for a node
        function findVisibleAncestor(nodeId) {
          let currentId = entryMap.get(nodeId)?.node.entry.parentId;
          while (currentId != null) {
            if (visibleIds.has(currentId)) {
              return currentId;
            }
            currentId = entryMap.get(currentId)?.node.entry.parentId;
          }
          return null;
        }

        // Build visible tree structure
        const visibleParent = new Map();
        const visibleChildren = new Map();
        visibleChildren.set(null, []); // root-level nodes

        for (const flatNode of filteredNodes) {
          const nodeId = flatNode.node.entry.id;
          const ancestorId = findVisibleAncestor(nodeId);
          visibleParent.set(nodeId, ancestorId);

          if (!visibleChildren.has(ancestorId)) {
            visibleChildren.set(ancestorId, []);
          }
          visibleChildren.get(ancestorId).push(nodeId);
        }

        // Update multipleRoots based on visible roots
        const visibleRootIds = visibleChildren.get(null);
        const multipleRoots = visibleRootIds.length > 1;

        // Build a map for quick lookup: nodeId → FlatNode
        const filteredNodeMap = new Map();
        for (const flatNode of filteredNodes) {
          filteredNodeMap.set(flatNode.node.entry.id, flatNode);
        }

        // DFS traversal of visible tree, applying same indentation rules as flattenTree()
        // Stack items: [nodeId, indent, justBranched, showConnector, isLast, gutters, isVirtualRootChild]
        const stack = [];

        // Add visible roots in reverse order (to process in forward order via stack)
        for (let i = visibleRootIds.length - 1; i >= 0; i--) {
          const isLast = i === visibleRootIds.length - 1;
          stack.push([
            visibleRootIds[i],
            multipleRoots ? 1 : 0,
            multipleRoots,
            multipleRoots,
            isLast,
            [],
            multipleRoots
          ]);
        }

        while (stack.length > 0) {
          const [nodeId, indent, justBranched, showConnector, isLast, gutters, isVirtualRootChild] = stack.pop();

          const flatNode = filteredNodeMap.get(nodeId);
          if (!flatNode) continue;

          // Update this node's visual properties
          flatNode.indent = indent;
          flatNode.showConnector = showConnector;
          flatNode.isLast = isLast;
          flatNode.gutters = gutters;
          flatNode.isVirtualRootChild = isVirtualRootChild;
          flatNode.multipleRoots = multipleRoots;

          // Get visible children of this node
          const children = visibleChildren.get(nodeId) || [];
          const multipleChildren = children.length > 1;

          // Calculate child indent using same rules as flattenTree():
          // - Parent branches (multiple children): children get +1
          // - Just branched and indent > 0: children get +1 for visual grouping
          // - Single-child chain: stay flat
          let childIndent;
          if (multipleChildren) {
            childIndent = indent + 1;
          } else if (justBranched && indent > 0) {
            childIndent = indent + 1;
          } else {
            childIndent = indent;
          }

          // Build gutters for children (same logic as flattenTree)
          const connectorDisplayed = showConnector && !isVirtualRootChild;
          const currentDisplayIndent = multipleRoots ? Math.max(0, indent - 1) : indent;
          const connectorPosition = Math.max(0, currentDisplayIndent - 1);
          const childGutters = connectorDisplayed
            ? [...gutters, { position: connectorPosition, show: !isLast }]
            : gutters;

          // Add children in reverse order (to process in forward order via stack)
          for (let i = children.length - 1; i >= 0; i--) {
            const childIsLast = i === children.length - 1;
            stack.push([
              children[i],
              childIndent,
              multipleChildren,
              multipleChildren,
              childIsLast,
              childGutters,
              false
            ]);
          }
        }
      }

      // ============================================================
      // TREE DISPLAY TEXT (pure data -> string)
      // ============================================================

      function shortenPath(p) {
        if (typeof p !== 'string') return '';
        if (p.startsWith('/Users/')) {
          const parts = p.split('/');
          if (parts.length > 2) return '~' + p.slice(('/Users/' + parts[2]).length);
        }
        if (p.startsWith('/home/')) {
          const parts = p.split('/');
          if (parts.length > 2) return '~' + p.slice(('/home/' + parts[2]).length);
        }
        return p;
      }

      function formatToolCall(name, args) {
        switch (name) {
          case 'read': {
            const path = shortenPath(String(args.path || args.file_path || ''));
            const offset = args.offset;
            const limit = args.limit;
            let display = path;
            if (offset !== undefined || limit !== undefined) {
              const start = offset ?? 1;
              const end = limit !== undefined ? start + limit - 1 : '';
              display += `:${start}${end ? `-${end}` : ''}`;
            }
            return `[read: ${display}]`;
          }
          case 'write':
            return `[write: ${shortenPath(String(args.path || args.file_path || ''))}]`;
          case 'edit':
            return `[edit: ${shortenPath(String(args.path || args.file_path || ''))}]`;
          case 'bash': {
            const rawCmd = String(args.command || '');
            const cmd = rawCmd.replace(/[\n\t]/g, ' ').trim().slice(0, 50);
            return `[bash: ${cmd}${rawCmd.length > 50 ? '...' : ''}]`;
          }
          case 'grep':
            return `[grep: /${args.pattern || ''}/ in ${shortenPath(String(args.path || '.'))}]`;
          case 'find':
            return `[find: ${args.pattern || ''} in ${shortenPath(String(args.path || '.'))}]`;
          case 'ls':
            return `[ls: ${shortenPath(String(args.path || '.'))}]`;
          default: {
            const argsStr = JSON.stringify(args).slice(0, 40);
            return `[${name}: ${argsStr}${JSON.stringify(args).length > 40 ? '...' : ''}]`;
          }
        }
      }

      function escapeHtml(text) {
        const div = document.createElement('div');
        div.textContent = text;
        return div.innerHTML;
      }

      /**
       * Truncate string to maxLen chars, append "..." if truncated.
       */
      function truncate(s, maxLen = 100) {
        if (s.length <= maxLen) return s;
        return s.slice(0, maxLen) + '...';
      }

      /**
       * Get display text for tree node (returns HTML string).
       */
      function getTreeNodeDisplayHtml(entry, label) {
        const normalize = s => s.replace(/[\n\t]/g, ' ').trim();
        const labelHtml = label ? `<span class="tree-label">[${escapeHtml(label)}]</span> ` : '';

        switch (entry.type) {
          case 'message': {
            const msg = entry.message;
            if (msg.role === 'user') {
              const content = truncate(normalize(extractContent(msg.content)));
              return labelHtml + `<span class="tree-role-user">user:</span> ${escapeHtml(content)}`;
            }
            if (msg.role === 'assistant') {
              const textContent = truncate(normalize(extractContent(msg.content)));
              if (textContent) {
                return labelHtml + `<span class="tree-role-assistant">assistant:</span> ${escapeHtml(textContent)}`;
              }
              if (msg.stopReason === 'aborted') {
                return labelHtml + `<span class="tree-role-assistant">assistant:</span> <span class="tree-muted">(aborted)</span>`;
              }
              if (msg.errorMessage) {
                return labelHtml + `<span class="tree-role-assistant">assistant:</span> <span class="tree-error">${escapeHtml(truncate(msg.errorMessage))}</span>`;
              }
              return labelHtml + `<span class="tree-role-assistant">assistant:</span> <span class="tree-muted">(no text)</span>`;
            }
            if (msg.role === 'toolResult') {
              const toolCall = msg.toolCallId ? toolCallMap.get(msg.toolCallId) : null;
              if (toolCall) {
                return labelHtml + `<span class="tree-role-tool">${escapeHtml(formatToolCall(toolCall.name, toolCall.arguments))}</span>`;
              }
              return labelHtml + `<span class="tree-role-tool">[${msg.toolName || 'tool'}]</span>`;
            }
            if (msg.role === 'bashExecution') {
              const cmd = truncate(normalize(msg.command || ''));
              return labelHtml + `<span class="tree-role-tool">[bash]:</span> ${escapeHtml(cmd)}`;
            }
            return labelHtml + `<span class="tree-muted">[${msg.role}]</span>`;
          }
          case 'compaction':
            return labelHtml + `<span class="tree-compaction">[compaction: ${Math.round(entry.tokensBefore/1000)}k tokens]</span>`;
          case 'branch_summary': {
            const summary = truncate(normalize(entry.summary || ''));
            return labelHtml + `<span class="tree-branch-summary">[branch summary]:</span> ${escapeHtml(summary)}`;
          }
          case 'custom_message': {
            const content = typeof entry.content === 'string' ? entry.content : extractContent(entry.content);
            return labelHtml + `<span class="tree-custom">[${escapeHtml(entry.customType)}]:</span> ${escapeHtml(truncate(normalize(content)))}`;
          }
          case 'model_change':
            return labelHtml + `<span class="tree-muted">[model: ${entry.modelId}]</span>`;
          case 'thinking_level_change':
            return labelHtml + `<span class="tree-muted">[thinking: ${entry.thinkingLevel}]</span>`;
          default:
            return labelHtml + `<span class="tree-muted">[${entry.type}]</span>`;
        }
      }

      // ============================================================
      // TREE RENDERING (DOM manipulation)
      // ============================================================

      let currentLeafId = leafId;
      let currentTargetId = urlTargetId || leafId;
      let treeRendered = false;

      function renderTree() {
        const tree = buildTree();
        const activePathIds = buildActivePathIds(currentLeafId);
        const flatNodes = flattenTree(tree, activePathIds);
        const filtered = filterNodes(flatNodes, currentLeafId);
        const container = document.getElementById('tree-container');

        // Full render only on first call or when filter/search changes
        if (!treeRendered) {
          container.innerHTML = '';

          for (const flatNode of filtered) {
            const entry = flatNode.node.entry;
            const isOnPath = activePathIds.has(entry.id);
            const isTarget = entry.id === currentTargetId;

            const div = document.createElement('div');
            div.className = 'tree-node';
            if (isOnPath) div.classList.add('in-path');
            if (isTarget) div.classList.add('active');
            div.dataset.id = entry.id;

            const prefix = buildTreePrefix(flatNode);
            const prefixSpan = document.createElement('span');
            prefixSpan.className = 'tree-prefix';
            prefixSpan.textContent = prefix;

            const marker = document.createElement('span');
            marker.className = 'tree-marker';
            marker.textContent = isOnPath ? '•' : ' ';

            const content = document.createElement('span');
            content.className = 'tree-content';
            content.innerHTML = getTreeNodeDisplayHtml(entry, flatNode.node.label);

            div.appendChild(prefixSpan);
            div.appendChild(marker);
            div.appendChild(content);
            // Navigate to the newest leaf through this node, but scroll to the clicked node
            div.addEventListener('click', () => {
              const leafId = findNewestLeaf(entry.id);
              navigateTo(leafId, 'target', entry.id);
            });

            container.appendChild(div);
          }

          treeRendered = true;
        } else {
          // Just update markers and classes
          const nodes = container.querySelectorAll('.tree-node');
          for (const node of nodes) {
            const id = node.dataset.id;
            const isOnPath = activePathIds.has(id);
            const isTarget = id === currentTargetId;

            node.classList.toggle('in-path', isOnPath);
            node.classList.toggle('active', isTarget);

            const marker = node.querySelector('.tree-marker');
            if (marker) {
              marker.textContent = isOnPath ? '•' : ' ';
            }
          }
        }

        document.getElementById('tree-status').textContent = `${filtered.length} / ${flatNodes.length} entries`;

        // Scroll active node into view after layout
        setTimeout(() => {
          const activeNode = container.querySelector('.tree-node.active');
          if (activeNode) {
            activeNode.scrollIntoView({ block: 'nearest' });
          }
        }, 0);
      }

      function forceTreeRerender() {
        treeRendered = false;
        renderTree();
      }

      // ============================================================
      // MESSAGE RENDERING
      // ============================================================

      function formatTokens(count) {
        if (count < 1000) return count.toString();
        if (count < 10000) return (count / 1000).toFixed(1) + 'k';
        if (count < 1000000) return Math.round(count / 1000) + 'k';
        return (count / 1000000).toFixed(1) + 'M';
      }

      function formatTimestamp(ts) {
        if (!ts) return '';
        const date = new Date(ts);
        return date.toLocaleTimeString(undefined, { hour: '2-digit', minute: '2-digit', second: '2-digit' });
      }

      function replaceTabs(text) {
        return text.replace(/\t/g, '   ');
      }

      /** Safely coerce value to string for display. Returns null if invalid type. */
      function str(value) {
        if (typeof value === 'string') return value;
        if (value == null) return '';
        return null;
      }

      function getLanguageFromPath(filePath) {
        const ext = filePath.split('.').pop()?.toLowerCase();
        const extToLang = {
          ts: 'typescript', tsx: 'typescript', js: 'javascript', jsx: 'javascript',
          py: 'python', rb: 'ruby', rs: 'rust', go: 'go', java: 'java',
          c: 'c', cpp: 'cpp', h: 'c', hpp: 'cpp', cs: 'csharp',
          php: 'php', sh: 'bash', bash: 'bash', zsh: 'bash',
          sql: 'sql', html: 'html', css: 'css', scss: 'scss',
          json: 'json', yaml: 'yaml', yml: 'yaml', xml: 'xml',
          md: 'markdown', dockerfile: 'dockerfile'
        };
        return extToLang[ext];
      }

      function findToolResult(toolCallId) {
        for (const entry of entries) {
          if (entry.type === 'message' && entry.message.role === 'toolResult') {
            if (entry.message.toolCallId === toolCallId) {
              return entry.message;
            }
          }
        }
        return null;
      }

      function formatExpandableOutput(text, maxLines, lang) {
        text = replaceTabs(text);
        const lines = text.split('\n');
        const displayLines = lines.slice(0, maxLines);
        const remaining = lines.length - maxLines;

        if (lang) {
          let highlighted;
          try {
            highlighted = hljs.highlight(text, { language: lang }).value;
          } catch {
            highlighted = escapeHtml(text);
          }

          if (remaining > 0) {
            const previewCode = displayLines.join('\n');
            let previewHighlighted;
            try {
              previewHighlighted = hljs.highlight(previewCode, { language: lang }).value;
            } catch {
              previewHighlighted = escapeHtml(previewCode);
            }

            return `<div class="tool-output expandable" onclick="this.classList.toggle('expanded')">
              <div class="output-preview"><pre><code class="hljs">${previewHighlighted}</code></pre>
              <div class="expand-hint">... (${remaining} more lines)</div></div>
              <div class="output-full"><pre><code class="hljs">${highlighted}</code></pre></div></div>`;
          }

          return `<div class="tool-output"><pre><code class="hljs">${highlighted}</code></pre></div>`;
        }

        // Plain text output
        if (remaining > 0) {
          let out = '<div class="tool-output expandable" onclick="this.classList.toggle(\'expanded\')">';
          out += '<div class="output-preview">';
          for (const line of displayLines) {
            out += `<div>${escapeHtml(replaceTabs(line))}</div>`;
          }
          out += `<div class="expand-hint">... (${remaining} more lines)</div></div>`;
          out += '<div class="output-full">';
          for (const line of lines) {
            out += `<div>${escapeHtml(replaceTabs(line))}</div>`;
          }
          out += '</div></div>';
          return out;
        }

        let out = '<div class="tool-output">';
        for (const line of displayLines) {
          out += `<div>${escapeHtml(replaceTabs(line))}</div>`;
        }
        out += '</div>';
        return out;
      }

      function renderToolCall(call) {
        const result = findToolResult(call.id);
        const isError = result?.isError || false;
        const statusClass = result ? (isError ? 'error' : 'success') : 'pending';

        const getResultText = () => {
          if (!result) return '';
          const textBlocks = result.content.filter(c => c.type === 'text');
          return textBlocks.map(c => c.text).join('\n');
        };

        const getResultImages = () => {
          if (!result) return [];
          return result.content.filter(c => c.type === 'image');
        };

        const renderResultImages = () => {
          const images = getResultImages();
          if (images.length === 0) return '';
          return '<div class="tool-images">' + 
            images.map(img => `<img src="data:${img.mimeType};base64,${img.data}" class="tool-image" />`).join('') + 
            '</div>';
        };

        let html = `<div class="tool-execution ${statusClass}">`;
        const args = call.arguments || {};
        const name = call.name;

        const invalidArg = '<span class="tool-error">[invalid arg]</span>';

        switch (name) {
          case 'bash': {
            const command = str(args.command);
            const cmdDisplay = command === null ? invalidArg : escapeHtml(command || '...');
            html += `<div class="tool-command">$ ${cmdDisplay}</div>`;
            if (result) {
              const output = getResultText().trim();
              if (output) html += formatExpandableOutput(output, 5);
            }
            break;
          }
          case 'read': {
            const filePath = str(args.file_path ?? args.path);
            const offset = args.offset;
            const limit = args.limit;

            let pathHtml = filePath === null ? invalidArg : escapeHtml(shortenPath(filePath || ''));
            if (filePath !== null && (offset !== undefined || limit !== undefined)) {
              const startLine = offset ?? 1;
              const endLine = limit !== undefined ? startLine + limit - 1 : '';
              pathHtml += `<span class="line-numbers">:${startLine}${endLine ? '-' + endLine : ''}</span>`;
            }

            html += `<div class="tool-header"><span class="tool-name">read</span> <span class="tool-path">${pathHtml}</span></div>`;
            if (result) {
              html += renderResultImages();
              const output = getResultText();
              const lang = filePath ? getLanguageFromPath(filePath) : null;
              if (output) html += formatExpandableOutput(output, 10, lang);
            }
            break;
          }
          case 'write': {
            const filePath = str(args.file_path ?? args.path);
            const content = str(args.content);

            html += `<div class="tool-header"><span class="tool-name">write</span> <span class="tool-path">${filePath === null ? invalidArg : escapeHtml(shortenPath(filePath || ''))}</span>`;
            if (content !== null && content) {
              const lines = content.split('\n');
              if (lines.length > 10) html += ` <span class="line-count">(${lines.length} lines)</span>`;
            }
            html += '</div>';

            if (content === null) {
              html += `<div class="tool-error">[invalid content arg - expected string]</div>`;
            } else if (content) {
              const lang = filePath ? getLanguageFromPath(filePath) : null;
              html += formatExpandableOutput(content, 10, lang);
            }
            if (result) {
              const output = getResultText().trim();
              if (output) html += `<div class="tool-output"><div>${escapeHtml(output)}</div></div>`;
            }
            break;
          }
          case 'edit': {
            const filePath = str(args.file_path ?? args.path);
            html += `<div class="tool-header"><span class="tool-name">edit</span> <span class="tool-path">${filePath === null ? invalidArg : escapeHtml(shortenPath(filePath || ''))}</span></div>`;

            if (result?.details?.diff) {
              const diffLines = result.details.diff.split('\n');
              html += '<div class="tool-diff">';
              for (const line of diffLines) {
                const cls = line.match(/^\+/) ? 'diff-added' : line.match(/^-/) ? 'diff-removed' : 'diff-context';
                html += `<div class="${cls}">${escapeHtml(replaceTabs(line))}</div>`;
              }
              html += '</div>';
            } else if (result) {
              const output = getResultText().trim();
              if (output) html += `<div class="tool-output"><pre>${escapeHtml(output)}</pre></div>`;
            }
            break;
          }
          default: {
            // Check for pre-rendered custom tool HTML
            const rendered = renderedTools?.[call.id];
            if (rendered?.callHtml || rendered?.resultHtml) {
              // Custom tool with pre-rendered HTML from TUI renderer
              if (rendered.callHtml) {
                html += `<div class="tool-header ansi-rendered">${rendered.callHtml}</div>`;
              } else {
                html += `<div class="tool-header"><span class="tool-name">${escapeHtml(name)}</span></div>`;
              }
              
              if (rendered.resultHtml) {
                // Apply same truncation as built-in tools (10 lines)
                const lines = rendered.resultHtml.split('\n');
                if (lines.length > 10) {
                  const preview = lines.slice(0, 10).join('\n');
                  html += `<div class="tool-output expandable ansi-rendered" onclick="this.classList.toggle('expanded')">
                    <div class="output-preview">${preview}<div class="expand-hint">... (${lines.length - 10} more lines)</div></div>
                    <div class="output-full">${rendered.resultHtml}</div>
                  </div>`;
                } else {
                  html += `<div class="tool-output ansi-rendered">${rendered.resultHtml}</div>`;
                }
              } else if (result) {
                // Fallback to JSON for result if no pre-rendered HTML
                const output = getResultText();
                if (output) html += formatExpandableOutput(output, 10);
              }
            } else {
              // Fallback to JSON display (existing behavior)
              html += `<div class="tool-header"><span class="tool-name">${escapeHtml(name)}</span></div>`;
              html += `<div class="tool-output"><pre>${escapeHtml(JSON.stringify(args, null, 2))}</pre></div>`;
              if (result) {
                const output = getResultText();
                if (output) html += formatExpandableOutput(output, 10);
              }
            }
          }
        }

        html += '</div>';
        return html;
      }

      /**
       * Download the session data as a JSONL file.
       * Reconstructs the original format: header line + entry lines.
       */
      window.downloadSessionJson = function() {
        // Build JSONL content: header first, then all entries
        const lines = [];
        if (header) {
          lines.push(JSON.stringify({ type: 'header', ...header }));
        }
        for (const entry of entries) {
          lines.push(JSON.stringify(entry));
        }
        const jsonlContent = lines.join('\n');

        // Create download
        const blob = new Blob([jsonlContent], { type: 'application/x-ndjson' });
        const url = URL.createObjectURL(blob);
        const a = document.createElement('a');
        a.href = url;
        a.download = `${header?.id || 'session'}.jsonl`;
        document.body.appendChild(a);
        a.click();
        document.body.removeChild(a);
        URL.revokeObjectURL(url);
      }

      /**
       * Build a shareable URL for a specific message.
       * URL format: base?gistId&leafId=<leafId>&targetId=<entryId>
       */
      function buildShareUrl(entryId) {
        // Check for injected base URL (used when loaded in iframe via srcdoc)
        const baseUrlMeta = document.querySelector('meta[name="pi-share-base-url"]');
        const baseUrl = baseUrlMeta ? baseUrlMeta.content : window.location.href.split('?')[0];
        
        const url = new URL(window.location.href);
        // Find the gist ID (first query param without value, e.g., ?abc123)
        const gistId = Array.from(url.searchParams.keys()).find(k => !url.searchParams.get(k));
        
        // Build the share URL
        const params = new URLSearchParams();
        params.set('leafId', currentLeafId);
        params.set('targetId', entryId);
        
        // If we have an injected base URL (iframe context), use it directly
        if (baseUrlMeta) {
          return `${baseUrl}&${params.toString()}`;
        }
        
        // Otherwise build from current location (direct file access)
        url.search = gistId ? `?${gistId}&${params.toString()}` : `?${params.toString()}`;
        return url.toString();
      }

      /**
       * Copy text to clipboard with visual feedback.
       * Uses navigator.clipboard with fallback to execCommand for HTTP contexts.
       */
      async function copyToClipboard(text, button) {
        let success = false;
        try {
          if (navigator.clipboard && navigator.clipboard.writeText) {
            await navigator.clipboard.writeText(text);
            success = true;
          }
        } catch (err) {
          // Clipboard API failed, try fallback
        }
        
        // Fallback for HTTP or when Clipboard API is unavailable
        if (!success) {
          try {
            const textarea = document.createElement('textarea');
            textarea.value = text;
            textarea.style.position = 'fixed';
            textarea.style.opacity = '0';
            document.body.appendChild(textarea);
            textarea.select();
            success = document.execCommand('copy');
            document.body.removeChild(textarea);
          } catch (err) {
            console.error('Failed to copy:', err);
          }
        }
        
        if (success && button) {
          const originalHtml = button.innerHTML;
          button.innerHTML = '✓';
          button.classList.add('copied');
          setTimeout(() => {
            button.innerHTML = originalHtml;
            button.classList.remove('copied');
          }, 1500);
        }
      }

      /**
       * Render the copy-link button HTML for a message.
       */
      function renderCopyLinkButton(entryId) {
        return `<button class="copy-link-btn" data-entry-id="${entryId}" title="Copy link to this message">
          <svg width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
            <path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"/>
            <path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"/>
          </svg>
        </button>`;
      }

      function renderEntry(entry) {
        const ts = formatTimestamp(entry.timestamp);
        const tsHtml = ts ? `<div class="message-timestamp">${ts}</div>` : '';
        const entryId = `entry-${entry.id}`;
        const copyBtnHtml = renderCopyLinkButton(entry.id);

        if (entry.type === 'message') {
          const msg = entry.message;

          if (msg.role === 'user') {
            let html = `<div class="user-message" id="${entryId}">${copyBtnHtml}${tsHtml}`;
            const content = msg.content;

            if (Array.isArray(content)) {
              const images = content.filter(c => c.type === 'image');
              if (images.length > 0) {
                html += '<div class="message-images">';
                for (const img of images) {
                  html += `<img src="data:${img.mimeType};base64,${img.data}" class="message-image" />`;
                }
                html += '</div>';
              }
            }

            const text = typeof content === 'string' ? content : 
              content.filter(c => c.type === 'text').map(c => c.text).join('\n');
            if (text.trim()) {
              html += `<div class="markdown-content">${safeMarkedParse(text)}</div>`;
            }
            html += '</div>';
            return html;
          }

          if (msg.role === 'assistant') {
            let html = `<div class="assistant-message" id="${entryId}">${copyBtnHtml}${tsHtml}`;

            for (const block of msg.content) {
              if (block.type === 'text' && block.text.trim()) {
                html += `<div class="assistant-text markdown-content">${safeMarkedParse(block.text)}</div>`;
              } else if (block.type === 'thinking' && block.thinking.trim()) {
                html += `<div class="thinking-block">
                  <div class="thinking-text">${escapeHtml(block.thinking)}</div>
                  <div class="thinking-collapsed">Thinking ...</div>
                </div>`;
              }
            }

            for (const block of msg.content) {
              if (block.type === 'toolCall') {
                html += renderToolCall(block);
              }
            }

            if (msg.stopReason === 'aborted') {
              html += '<div class="error-text">Aborted</div>';
            } else if (msg.stopReason === 'error') {
              html += `<div class="error-text">Error: ${escapeHtml(msg.errorMessage || 'Unknown error')}</div>`;
            }

            html += '</div>';
            return html;
          }

          if (msg.role === 'bashExecution') {
            const isError = msg.cancelled || (msg.exitCode !== 0 && msg.exitCode !== null);
            let html = `<div class="tool-execution ${isError ? 'error' : 'success'}" id="${entryId}">${tsHtml}`;
            html += `<div class="tool-command">$ ${escapeHtml(msg.command)}</div>`;
            if (msg.output) html += formatExpandableOutput(msg.output, 10);
            if (msg.cancelled) {
              html += '<div style="color: var(--warning)">(cancelled)</div>';
            } else if (msg.exitCode !== 0 && msg.exitCode !== null) {
              html += `<div style="color: var(--error)">(exit ${msg.exitCode})</div>`;
            }
            html += '</div>';
            return html;
          }

          if (msg.role === 'toolResult') return '';
        }

        if (entry.type === 'model_change') {
          return `<div class="model-change" id="${entryId}">${tsHtml}Switched to model: <span class="model-name">${escapeHtml(entry.provider)}/${escapeHtml(entry.modelId)}</span></div>`;
        }

        if (entry.type === 'compaction') {
          return `<div class="compaction" id="${entryId}" onclick="this.classList.toggle('expanded')">
            <div class="compaction-label">[compaction]</div>
            <div class="compaction-collapsed">Compacted from ${entry.tokensBefore.toLocaleString()} tokens</div>
            <div class="compaction-content"><strong>Compacted from ${entry.tokensBefore.toLocaleString()} tokens</strong>\n\n${escapeHtml(entry.summary)}</div>
          </div>`;
        }

        if (entry.type === 'branch_summary') {
          return `<div class="branch-summary" id="${entryId}">${tsHtml}
            <div class="branch-summary-header">Branch Summary</div>
            <div class="markdown-content">${safeMarkedParse(entry.summary)}</div>
          </div>`;
        }

        if (entry.type === 'custom_message' && entry.display) {
          return `<div class="hook-message" id="${entryId}">${tsHtml}
            <div class="hook-type">[${escapeHtml(entry.customType)}]</div>
            <div class="markdown-content">${safeMarkedParse(typeof entry.content === 'string' ? entry.content : JSON.stringify(entry.content))}</div>
          </div>`;
        }

        return '';
      }

      // ============================================================
      // HEADER / STATS
      // ============================================================

      function computeStats(entryList) {
        let userMessages = 0, assistantMessages = 0, toolResults = 0;
        let customMessages = 0, compactions = 0, branchSummaries = 0, toolCalls = 0;
        const tokens = { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 };
        const cost = { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 };
        const models = new Set();

        for (const entry of entryList) {
          if (entry.type === 'message') {
            const msg = entry.message;
            if (msg.role === 'user') userMessages++;
            if (msg.role === 'assistant') {
              assistantMessages++;
              if (msg.model) models.add(msg.provider ? `${msg.provider}/${msg.model}` : msg.model);
              if (msg.usage) {
                tokens.input += msg.usage.input || 0;
                tokens.output += msg.usage.output || 0;
                tokens.cacheRead += msg.usage.cacheRead || 0;
                tokens.cacheWrite += msg.usage.cacheWrite || 0;
                if (msg.usage.cost) {
                  cost.input += msg.usage.cost.input || 0;
                  cost.output += msg.usage.cost.output || 0;
                  cost.cacheRead += msg.usage.cost.cacheRead || 0;
                  cost.cacheWrite += msg.usage.cost.cacheWrite || 0;
                }
              }
              toolCalls += msg.content.filter(c => c.type === 'toolCall').length;
            }
            if (msg.role === 'toolResult') toolResults++;
          } else if (entry.type === 'compaction') {
            compactions++;
          } else if (entry.type === 'branch_summary') {
            branchSummaries++;
          } else if (entry.type === 'custom_message') {
            customMessages++;
          }
        }

        return { userMessages, assistantMessages, toolResults, customMessages, compactions, branchSummaries, toolCalls, tokens, cost, models: Array.from(models) };
      }

      const globalStats = computeStats(entries);

      function renderHeader() {
        const totalCost = globalStats.cost.input + globalStats.cost.output + globalStats.cost.cacheRead + globalStats.cost.cacheWrite;

        const tokenParts = [];
        if (globalStats.tokens.input) tokenParts.push(`↑${formatTokens(globalStats.tokens.input)}`);
        if (globalStats.tokens.output) tokenParts.push(`↓${formatTokens(globalStats.tokens.output)}`);
        if (globalStats.tokens.cacheRead) tokenParts.push(`R${formatTokens(globalStats.tokens.cacheRead)}`);
        if (globalStats.tokens.cacheWrite) tokenParts.push(`W${formatTokens(globalStats.tokens.cacheWrite)}`);

        const msgParts = [];
        if (globalStats.userMessages) msgParts.push(`${globalStats.userMessages} user`);
        if (globalStats.assistantMessages) msgParts.push(`${globalStats.assistantMessages} assistant`);
        if (globalStats.toolResults) msgParts.push(`${globalStats.toolResults} tool results`);
        if (globalStats.customMessages) msgParts.push(`${globalStats.customMessages} custom`);
        if (globalStats.compactions) msgParts.push(`${globalStats.compactions} compactions`);
        if (globalStats.branchSummaries) msgParts.push(`${globalStats.branchSummaries} branch summaries`);

        let html = `
          <div class="header">
            <h1>Session: ${escapeHtml(header?.id || 'unknown')}</h1>
            <div class="help-bar">
              <span>Ctrl+T toggle thinking · Ctrl+O toggle tools</span>
              <button class="download-json-btn" onclick="downloadSessionJson()" title="Download session as JSONL">↓ JSONL</button>
            </div>
            <div class="header-info">
              <div class="info-item"><span class="info-label">Date:</span><span class="info-value">${header?.timestamp ? new Date(header.timestamp).toLocaleString() : 'unknown'}</span></div>
              <div class="info-item"><span class="info-label">Models:</span><span class="info-value">${globalStats.models.join(', ') || 'unknown'}</span></div>
              <div class="info-item"><span class="info-label">Messages:</span><span class="info-value">${msgParts.join(', ') || '0'}</span></div>
              <div class="info-item"><span class="info-label">Tool Calls:</span><span class="info-value">${globalStats.toolCalls}</span></div>
              <div class="info-item"><span class="info-label">Tokens:</span><span class="info-value">${tokenParts.join(' ') || '0'}</span></div>
              <div class="info-item"><span class="info-label">Cost:</span><span class="info-value">$${totalCost.toFixed(3)}</span></div>
            </div>
          </div>`;

        // Render system prompt (user's base prompt, applies to all providers)
        if (systemPrompt) {
          const lines = systemPrompt.split('\n');
          const previewLines = 10;
          if (lines.length > previewLines) {
            const preview = lines.slice(0, previewLines).join('\n');
            const remaining = lines.length - previewLines;
            html += `<div class="system-prompt expandable" onclick="this.classList.toggle('expanded')">
              <div class="system-prompt-header">System Prompt</div>
              <div class="system-prompt-preview">${escapeHtml(preview)}</div>
              <div class="system-prompt-expand-hint">... (${remaining} more lines, click to expand)</div>
              <div class="system-prompt-full">${escapeHtml(systemPrompt)}</div>
            </div>`;
          } else {
            html += `<div class="system-prompt">
              <div class="system-prompt-header">System Prompt</div>
              <div class="system-prompt-full" style="display: block">${escapeHtml(systemPrompt)}</div>
            </div>`;
          }
        }

        if (tools && tools.length > 0) {
          html += `<div class="tools-list">
            <div class="tools-header">Available Tools</div>
            <div class="tools-content">
              ${tools.map(t => {
                const hasParams = t.parameters && typeof t.parameters === 'object' && t.parameters.properties && Object.keys(t.parameters.properties).length > 0;
                if (!hasParams) {
                  return `<div class="tool-item"><span class="tool-item-name">${escapeHtml(t.name)}</span> - <span class="tool-item-desc">${escapeHtml(t.description)}</span></div>`;
                }
                const params = t.parameters;
                const properties = params.properties;
                const required = params.required || [];
                let paramsHtml = '';
                for (const [name, prop] of Object.entries(properties)) {
                  const isRequired = required.includes(name);
                  const typeStr = prop.type || 'any';
                  const reqLabel = isRequired ? '<span class="tool-param-required">required</span>' : '<span class="tool-param-optional">optional</span>';
                  paramsHtml += `<div class="tool-param"><span class="tool-param-name">${escapeHtml(name)}</span> <span class="tool-param-type">${escapeHtml(typeStr)}</span> ${reqLabel}`;
                  if (prop.description) {
                    paramsHtml += `<div class="tool-param-desc">${escapeHtml(prop.description)}</div>`;
                  }
                  paramsHtml += `</div>`;
                }
                return `<div class="tool-item" onclick="this.classList.toggle('params-expanded')"><span class="tool-item-name">${escapeHtml(t.name)}</span> - <span class="tool-item-desc">${escapeHtml(t.description)}</span> <span class="tool-params-hint"></span><div class="tool-params-content">${paramsHtml}</div></div>`;
              }).join('')}
            </div>
          </div>`;
        }

        return html;
      }

      // ============================================================
      // NAVIGATION
      // ============================================================

      // Cache for rendered entry DOM nodes
      const entryCache = new Map();

      function renderEntryToNode(entry) {
        // Check cache first
        if (entryCache.has(entry.id)) {
          return entryCache.get(entry.id).cloneNode(true);
        }

        // Render to HTML string, then parse to node
        const html = renderEntry(entry);
        if (!html) return null;

        const template = document.createElement('template');
        template.innerHTML = html;
        const node = template.content.firstElementChild;

        // Cache the node
        if (node) {
          entryCache.set(entry.id, node.cloneNode(true));
        }
        return node;
      }

      function navigateTo(targetId, scrollMode = 'target', scrollToEntryId = null) {
        currentLeafId = targetId;
        currentTargetId = scrollToEntryId || targetId;
        const path = getPath(targetId);

        renderTree();

        document.getElementById('header-container').innerHTML = renderHeader();

        // Build messages using cached DOM nodes
        const messagesEl = document.getElementById('messages');
        const fragment = document.createDocumentFragment();

        for (const entry of path) {
          const node = renderEntryToNode(entry);
          if (node) {
            fragment.appendChild(node);
          }
        }

        messagesEl.innerHTML = '';
        messagesEl.appendChild(fragment);

        // Attach click handlers for copy-link buttons
        messagesEl.querySelectorAll('.copy-link-btn').forEach(btn => {
          btn.addEventListener('click', (e) => {
            e.stopPropagation();
            const entryId = btn.dataset.entryId;
            const shareUrl = buildShareUrl(entryId);
            copyToClipboard(shareUrl, btn);
          });
        });

        // Use setTimeout(0) to ensure DOM is fully laid out before scrolling
        setTimeout(() => {
          const content = document.getElementById('content');
          if (scrollMode === 'bottom') {
            content.scrollTop = content.scrollHeight;
          } else if (scrollMode === 'target') {
            // If scrollToEntryId is provided, scroll to that specific entry
            const scrollTargetId = scrollToEntryId || targetId;
            const targetEl = document.getElementById(`entry-${scrollTargetId}`);
            if (targetEl) {
              targetEl.scrollIntoView({ block: 'center' });
              // Briefly highlight the target message
              if (scrollToEntryId) {
                targetEl.classList.add('highlight');
                setTimeout(() => targetEl.classList.remove('highlight'), 2000);
              }
            }
          }
        }, 0);
      }

      // ============================================================
      // INITIALIZATION
      // ============================================================

      // Escape HTML tags in text (but not code blocks)
      function escapeHtmlTags(text) {
        return text.replace(/<(?=[a-zA-Z\/])/g, '&lt;');
      }

      // Configure marked with syntax highlighting and HTML escaping for text
      marked.use({
        breaks: true,
        gfm: true,
        renderer: {
          // Code blocks: syntax highlight, no HTML escaping
          code(token) {
            const code = token.text;
            const lang = token.lang;
            let highlighted;
            if (lang && hljs.getLanguage(lang)) {
              try {
                highlighted = hljs.highlight(code, { language: lang }).value;
              } catch {
                highlighted = escapeHtml(code);
              }
            } else {
              // Auto-detect language if not specified
              try {
                highlighted = hljs.highlightAuto(code).value;
              } catch {
                highlighted = escapeHtml(code);
              }
            }
            return `<pre><code class="hljs">${highlighted}</code></pre>`;
          },
          // Text content: escape HTML tags
          text(token) {
            return escapeHtmlTags(escapeHtml(token.text));
          },
          // Inline code: escape HTML
          codespan(token) {
            return `<code>${escapeHtml(token.text)}</code>`;
          }
        }
      });

      // Simple marked parse (escaping handled in renderers)
      function safeMarkedParse(text) {
        return marked.parse(text);
      }

      // Search input
      const searchInput = document.getElementById('tree-search');
      searchInput.addEventListener('input', (e) => {
        searchQuery = e.target.value;
        forceTreeRerender();
      });

      // Filter buttons
      document.querySelectorAll('.filter-btn').forEach(btn => {
        btn.addEventListener('click', () => {
          document.querySelectorAll('.filter-btn').forEach(b => b.classList.remove('active'));
          btn.classList.add('active');
          filterMode = btn.dataset.filter;
          forceTreeRerender();
        });
      });

      // Sidebar toggle
      const sidebar = document.getElementById('sidebar');
      const overlay = document.getElementById('sidebar-overlay');
      const hamburger = document.getElementById('hamburger');

      hamburger.addEventListener('click', () => {
        sidebar.classList.add('open');
        overlay.classList.add('open');
        hamburger.style.display = 'none';
      });

      const closeSidebar = () => {
        sidebar.classList.remove('open');
        overlay.classList.remove('open');
        hamburger.style.display = '';
      };

      overlay.addEventListener('click', closeSidebar);
      document.getElementById('sidebar-close').addEventListener('click', closeSidebar);

      // Toggle states
      let thinkingExpanded = true;
      let toolOutputsExpanded = false;

      const toggleThinking = () => {
        thinkingExpanded = !thinkingExpanded;
        document.querySelectorAll('.thinking-text').forEach(el => {
          el.style.display = thinkingExpanded ? '' : 'none';
        });
        document.querySelectorAll('.thinking-collapsed').forEach(el => {
          el.style.display = thinkingExpanded ? 'none' : 'block';
        });
      };

      const toggleToolOutputs = () => {
        toolOutputsExpanded = !toolOutputsExpanded;
        document.querySelectorAll('.tool-output.expandable').forEach(el => {
          el.classList.toggle('expanded', toolOutputsExpanded);
        });
        document.querySelectorAll('.compaction').forEach(el => {
          el.classList.toggle('expanded', toolOutputsExpanded);
        });
      };

      // Keyboard shortcuts
      document.addEventListener('keydown', (e) => {
        if (e.key === 'Escape') {
          searchInput.value = '';
          searchQuery = '';
          navigateTo(leafId, 'bottom');
        }
        if (e.ctrlKey && e.key === 't') {
          e.preventDefault();
          toggleThinking();
        }
        if (e.ctrlKey && e.key === 'o') {
          e.preventDefault();
          toggleToolOutputs();
        }
      });

      // Initial render
      // If URL has targetId, scroll to that specific message; otherwise stay at top
      if (leafId) {
        if (urlTargetId && byId.has(urlTargetId)) {
          // Deep link: navigate to leaf and scroll to target message
          navigateTo(leafId, 'target', urlTargetId);
        } else {
          navigateTo(leafId, 'none');
        }
      } else if (entries.length > 0) {
        // Fallback: use last entry if no leafId
        navigateTo(entries[entries.length - 1].id, 'none');
      }
    })();