(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");
  }
})();