"use strict";

const FALLBACK_FEEDBACK = "Revise the review to better match the rubric's content, tone, style, and length.";
const state = {
  index: null,
  trajectories: [],
  visible: [],
  checkpoints: [],
  payload: null,
  activeRound: 0,
  view: "trajectory",
};

const byId = (id) => document.getElementById(id);
const finite = (value) => value !== null && value !== undefined && Number.isFinite(Number(value));
const number = (value) => (finite(value) ? Number(value) : null);

function formatScore(value, digits = 3) {
  return finite(value) ? Number(value).toFixed(digits) : "N/A";
}

function formatSigned(value, digits = 3) {
  if (!finite(value)) return "N/A";
  const numeric = Number(value);
  return `${numeric > 0 ? "+" : ""}${numeric.toFixed(digits)}`;
}

function formatPercent(value, digits = 1) {
  if (!finite(value)) return "N/A";
  return `${(Number(value) * 100).toFixed(digits)}%`;
}

function mean(values) {
  const valid = values.filter(finite).map(Number);
  return valid.length ? valid.reduce((total, value) => total + value, 0) / valid.length : null;
}

function words(value) {
  return String(value || "").trim().split(/\s+/).filter(Boolean).length;
}

function cleanResearchText(value) {
  return String(value || "")
    .replace(/<br\s*\/?>/gi, "\n")
    .replace(/<\/?(?:response|rubric)>/gi, "")
    .replace(/&(#x[0-9a-f]+|#\d+|quot|amp|apos|lt|gt|nbsp);/gi, (match, entity) => {
      const named = { quot: '"', amp: "&", apos: "'", lt: "<", gt: ">", nbsp: " " };
      const lowered = entity.toLowerCase();
      if (Object.prototype.hasOwnProperty.call(named, lowered)) return named[lowered];
      const numeric = lowered.startsWith("#x")
        ? Number.parseInt(lowered.slice(2), 16)
        : Number.parseInt(lowered.slice(1), 10);
      if (!Number.isInteger(numeric) || numeric < 0 || numeric > 0x10ffff) return match;
      try {
        return String.fromCodePoint(numeric);
      } catch (_error) {
        return match;
      }
    })
    .trim();
}

function appendInline(container, text) {
  const chunks = String(text).split(/(\*\*[^*]+\*\*)/g);
  chunks.forEach((chunk) => {
    if (chunk.startsWith("**") && chunk.endsWith("**") && chunk.length > 4) {
      const strong = document.createElement("strong");
      strong.textContent = chunk.slice(2, -2);
      container.appendChild(strong);
    } else {
      container.appendChild(document.createTextNode(chunk));
    }
  });
}

function renderStructured(container, value) {
  container.replaceChildren();
  const text = cleanResearchText(value);
  if (!text) {
    const empty = document.createElement("p");
    empty.textContent = "No text was logged.";
    container.appendChild(empty);
    return;
  }
  const blocks = text.split(/\n\s*\n/).filter((block) => block.trim());
  blocks.forEach((block) => {
    const lines = block.split("\n").filter((line) => line.trim());
    const numbered = lines.length > 1 && lines.every((line) => /^\s*\d+[.)]\s+/.test(line));
    if (numbered) {
      const list = document.createElement("ol");
      lines.forEach((line) => {
        const item = document.createElement("li");
        appendInline(item, line.replace(/^\s*\d+[.)]\s+/, ""));
        list.appendChild(item);
      });
      container.appendChild(list);
      return;
    }
    const paragraph = document.createElement("p");
    lines.forEach((line, index) => {
      if (index) paragraph.appendChild(document.createElement("br"));
      appendInline(paragraph, line);
    });
    container.appendChild(paragraph);
  });
}

function addOption(select, value, label) {
  const option = document.createElement("option");
  option.value = String(value);
  option.textContent = label;
  select.appendChild(option);
}

function badge(label, className = "") {
  const element = document.createElement("span");
  element.className = `badge ${className}`.trim();
  element.textContent = label;
  return element;
}

function metricCell(label, value, detail, className = "") {
  const cell = document.createElement("div");
  cell.className = `metric-cell ${className}`.trim();
  const name = document.createElement("span");
  name.textContent = label;
  const strong = document.createElement("strong");
  strong.textContent = value;
  cell.append(name, strong);
  if (detail) {
    const small = document.createElement("small");
    small.textContent = detail;
    cell.appendChild(small);
  }
  return cell;
}

function scorePill(label, value, className = "") {
  const pill = document.createElement("div");
  pill.className = `score-pill ${className}`.trim();
  const name = document.createElement("span");
  name.textContent = label;
  const strong = document.createElement("strong");
  strong.textContent = value;
  pill.append(name, strong);
  return pill;
}

function deltaClass(value) {
  if (!finite(value) || Math.abs(Number(value)) < 1e-9) return "";
  return Number(value) > 0 ? "positive" : "negative";
}

function outcomeLabel(value) {
  const labels = { improved: "Gold improved", unchanged: "Gold unchanged", worsened: "Gold worsened" };
  return labels[value] || String(value || "Outcome unavailable");
}

function trajectorySummary(record, payload = null) {
  return (payload && (payload.trajectory || payload.summary)) || record || {};
}

function trajectoryId(record) {
  return String(record.id || record.trajectory_id || record.path || "");
}

function trajectoryPath(record) {
  return String(record.path || record.data_path || `data/trajectories/${trajectoryId(record)}.json`);
}

function checkpointId(record) {
  return String(record.checkpoint_id || `${record.run_id || record.run_label || "run"}:${record.step}:${record.uid}`);
}

function checkpointLabel(checkpoint) {
  const title = checkpoint.title || checkpoint.context_label || checkpoint.uid || "Source example";
  const run = checkpoint.run_label || checkpoint.run_id || "run";
  return `Step ${checkpoint.step} · ${title} · ${run}`;
}

function buildCheckpointIndex() {
  const supplied = Array.isArray(state.index.checkpoints) ? state.index.checkpoints : [];
  const byKey = new Map(supplied.map((item) => [String(item.id || checkpointId(item)), { ...item }]));
  state.trajectories.forEach((record) => {
    const id = checkpointId(record);
    if (!byKey.has(id)) {
      byKey.set(id, {
        id,
        run_id: record.run_id,
        run_label: record.run_label,
        step: record.step,
        uid: record.uid,
        title: record.title,
        author: record.author,
        category: record.category,
      });
    }
    const checkpoint = byKey.get(id);
    checkpoint.id = id;
  });
  state.checkpoints = [...byKey.values()].sort((a, b) => Number(a.step) - Number(b.step) || String(a.run_id).localeCompare(String(b.run_id)));
}

function populateCheckpointSelect(preferred = null) {
  const select = byId("checkpoint-select");
  const current = preferred || select.value;
  select.replaceChildren();
  state.checkpoints.forEach((checkpoint) => addOption(select, checkpoint.id, checkpointLabel(checkpoint)));
  if (state.checkpoints.some((checkpoint) => checkpoint.id === current)) select.value = current;
  if (!select.value && state.checkpoints.length) select.value = state.checkpoints[0].id;
}

function applyTrajectoryFilter(preferredId = null) {
  const checkpoint = byId("checkpoint-select").value;
  const outcome = byId("outcome-select").value;
  let visible = state.trajectories.filter((record) => checkpointId(record) === checkpoint);
  if (outcome !== "all") visible = visible.filter((record) => String(record.outcome) === outcome);
  if (!visible.length && outcome !== "all") {
    byId("outcome-select").value = "all";
    visible = state.trajectories.filter((record) => checkpointId(record) === checkpoint);
  }
  state.visible = visible.sort((a, b) => Number(a.rubric_idx) - Number(b.rubric_idx) || Number(a.judge_idx) - Number(b.judge_idx));

  const select = byId("trajectory-select");
  const current = preferredId || select.value;
  select.replaceChildren();
  state.visible.forEach((record) => {
    const tie = Number(record.tie_count || 1) > 1 ? ` · ${record.tie_count}-way tie` : "";
    addOption(
      select,
      trajectoryId(record),
      `Rubric ${record.rubric_idx} · path ${record.judge_idx} · selected r${record.selected_round}${tie} · ${outcomeLabel(record.outcome)}`,
    );
  });
  if (state.visible.some((record) => trajectoryId(record) === current)) select.value = current;
  if (!select.value && state.visible.length) select.value = trajectoryId(state.visible[0]);
  updateTrajectoryPosition();
}

function selectedRecord() {
  const id = byId("trajectory-select").value;
  return state.visible.find((record) => trajectoryId(record) === id) || null;
}

function updateTrajectoryPosition() {
  const id = byId("trajectory-select").value;
  const index = state.visible.findIndex((record) => trajectoryId(record) === id);
  byId("trajectory-position").textContent = index >= 0 ? `${index + 1} of ${state.visible.length}` : "No paths";
  byId("previous-trajectory").disabled = index <= 0;
  byId("next-trajectory").disabled = index < 0 || index >= state.visible.length - 1;
}

async function loadSelectedTrajectory() {
  const record = selectedRecord();
  updateTrajectoryPosition();
  if (!record) {
    showError("No trajectory matches these filters.");
    return;
  }
  byId("loading").hidden = false;
  byId("trajectory-content").hidden = true;
  byId("error").hidden = true;
  try {
    const response = await fetch(trajectoryPath(record));
    if (!response.ok) throw new Error(`HTTP ${response.status}`);
    state.payload = await response.json();
    state.activeRound = 0;
    renderTrajectory(record, state.payload);
    byId("loading").hidden = true;
    byId("trajectory-content").hidden = false;
  } catch (error) {
    showError(`Could not load this trajectory (${error.message}).`);
  }
}

function showError(message) {
  byId("loading").hidden = true;
  byId("trajectory-content").hidden = true;
  byId("error").textContent = message;
  byId("error").hidden = false;
}

function extractContext(payload) {
  if (typeof payload.context === "string") return { text: payload.context };
  return payload.context || payload.source_context || {};
}

function extractRubric(payload) {
  if (typeof payload.rubric === "string") return { parsed: payload.rubric, generated: payload.rubric };
  return payload.rubric || {};
}

function extractPrompts(payload) {
  return payload.prompts || payload.prompt || {};
}

function renderTrajectory(record, payload) {
  const summary = trajectorySummary(record, payload);
  const checkpoint = payload.checkpoint || {};
  const context = extractContext(payload);
  const rubric = extractRubric(payload);
  const rounds = payload.rounds || payload.turns || [];
  payload.rounds = rounds;

  const title = context.title || checkpoint.title || record.title || "Target book";
  byId("record-eyebrow").textContent = `Step ${checkpoint.step ?? record.step} · ${checkpoint.run_label || record.run_label || checkpoint.run_id || record.run_id}`;
  byId("record-title").textContent = title;
  byId("record-subtitle").textContent = [context.author || record.author, context.category || record.category].filter(Boolean).join(" · ");
  byId("record-id").textContent = `${checkpoint.uid || record.uid} · rubric ${summary.rubric_idx ?? record.rubric_idx} · path ${summary.judge_idx ?? record.judge_idx}`;

  renderSummary(summary, rounds);
  renderContext(context, payload.target_response || payload.target || payload.reference_response || "");
  renderPrompts(extractPrompts(payload));
  renderRubric(rubric, summary, record);
  renderRoundTrack(rounds);
  renderRoundDetail(rounds);
  renderHistory(rounds);
  refreshIcons();
}

function summaryValue(summary, ...keys) {
  for (const key of keys) if (summary[key] !== undefined) return summary[key];
  return null;
}

function renderSummary(summary, rounds) {
  const initialGold = summaryValue(summary, "initial_gold") ?? rounds[0]?.gold_score;
  const lastGold = summaryValue(summary, "last_gold") ?? rounds.at(-1)?.gold_score;
  const selectedGold = summaryValue(summary, "selected_gold", "selected_gold_weighted");
  const bestGold = summaryValue(summary, "best_gold", "oracle_best_gold") ?? Math.max(...rounds.map((row) => Number(row.gold_score)));
  const selectedDelta = finite(selectedGold) && finite(initialGold) ? Number(selectedGold) - Number(initialGold) : null;
  const spearman = summaryValue(summary, "proxy_gold_spearman", "spearman");
  const tieCount = Number(summary.tie_count || summary.selected_tie_count || 1);
  const selectedRound = summary.selected_round;
  const container = byId("trajectory-summary");
  container.replaceChildren(
    metricCell("Initial gold", formatScore(initialGold), "round 0", "gold"),
    metricCell("Selected gold", formatScore(selectedGold), tieCount > 1 ? `mean of ${tieCount} tied rounds` : `round ${selectedRound}`, "gold"),
    metricCell("Selected change", formatSigned(selectedDelta), "selected minus initial", deltaClass(selectedDelta)),
    metricCell("Last gold", formatScore(lastGold), `round ${rounds.length - 1}`, "gold"),
    metricCell("Oracle best gold", formatScore(bestGold), "best logged state", "gold"),
    metricCell("Proxy-gold rank", formatScore(spearman), "Spearman across valid rounds", "proxy"),
  );
}

function renderContext(context, target) {
  const metadata = [
    ["Title", context.title],
    ["Author", context.author],
    ["Category", context.category],
    ["Store", context.store_label || context.store],
    ["Subtitle", context.subtitle],
    ["Price", context.price],
  ].filter(([, value]) => value !== null && value !== undefined && String(value).trim());
  const list = byId("context-meta");
  list.replaceChildren();
  metadata.forEach(([label, value]) => {
    const wrapper = document.createElement("div");
    const term = document.createElement("dt");
    term.textContent = label;
    const definition = document.createElement("dd");
    definition.textContent = String(value);
    wrapper.append(term, definition);
    list.appendChild(wrapper);
  });
  renderStructured(byId("context-text"), context.text || context.context || "");
  renderStructured(byId("target-response"), target);
  resetClamp("context-text", "context-toggle", "Show full context", "Collapse context");
}

function renderMessages(container, messages) {
  container.replaceChildren();
  (messages || []).forEach((message) => {
    const wrapper = document.createElement("article");
    wrapper.className = "message";
    const role = document.createElement("div");
    role.className = "message-role";
    role.textContent = message.role || "message";
    const content = document.createElement("div");
    content.className = "message-content";
    content.textContent = cleanResearchText(message.content || "");
    wrapper.append(role, content);
    container.appendChild(wrapper);
  });
  if (!messages || !messages.length) {
    const empty = document.createElement("p");
    empty.textContent = "No prompt messages were exported.";
    container.appendChild(empty);
  }
}

function renderPrompts(prompts) {
  const candidateMessages = prompts.candidate_messages || prompts.icl_messages || [];
  const rubricMessages = prompts.rubric_messages || prompts.rubric_prompt || [];
  renderMessages(byId("candidate-messages"), candidateMessages);
  renderMessages(byId("rubric-messages"), rubricMessages);
  byId("candidate-prompt-size").textContent = `${candidateMessages.length} messages · ${candidateMessages.reduce((total, item) => total + words(item.content), 0).toLocaleString()} words`;
  byId("rubric-prompt-size").textContent = `${rubricMessages.length} messages · ${rubricMessages.reduce((total, item) => total + words(item.content), 0).toLocaleString()} words`;
}

function renderRubric(rubric, summary, record) {
  const generated = rubric.generated || rubric.generated_rubric || rubric.parsed || rubric.parsed_rubric || "";
  const parsed = rubric.parsed || rubric.parsed_rubric || generated;
  renderStructured(byId("rubric-text"), generated);
  renderStructured(byId("parsed-rubric"), parsed);
  const exact = Boolean(parsed);
  byId("rubric-status").textContent = exact ? "Exact logged rubric" : "Rubric unavailable";
  byId("rubric-status").className = `status-badge ${exact ? "valid" : ""}`;
  byId("rubric-eyebrow").textContent = `Rubric ${summary.rubric_idx ?? record.rubric_idx} · shared by this judge path`;
  byId("parsed-rubric-size").textContent = `${words(parsed).toLocaleString()} words`;
  byId("parsed-rubric-details").hidden = parsed === generated;
  resetClamp("rubric-text", "rubric-toggle", "Show full rubric", "Collapse rubric");
}

function resetClamp(contentId, buttonId, collapsedLabel, expandedLabel) {
  const content = byId(contentId);
  const button = byId(buttonId);
  content.classList.add("is-clamped");
  button.setAttribute("aria-expanded", "false");
  button.textContent = collapsedLabel;
  button.dataset.collapsedLabel = collapsedLabel;
  button.dataset.expandedLabel = expandedLabel;
}

function renderRoundTrack(rounds) {
  const track = byId("round-track");
  track.replaceChildren();
  rounds.forEach((round, index) => {
    const button = document.createElement("button");
    const tie = Number(round.selection_weight || 0) > 0;
    button.type = "button";
    button.className = `round-button${index === state.activeRound ? " active" : ""}${tie ? " tie" : ""}`;
    button.setAttribute("role", "option");
    button.setAttribute("aria-selected", String(index === state.activeRound));
    button.dataset.round = String(index);
    const top = document.createElement("div");
    top.className = "round-button-top";
    const label = document.createElement("span");
    label.textContent = `Round ${round.round ?? index}`;
    const mark = document.createElement("span");
    mark.className = "round-button-mark";
    mark.textContent = round.selected_final ? "returned" : tie ? "top" : "";
    top.append(label, mark);
    const scores = document.createElement("div");
    scores.className = "round-button-scores";
    const proxy = document.createElement("span");
    proxy.textContent = `P ${formatScore(round.proxy_score, 2)}`;
    const gold = document.createElement("span");
    gold.textContent = `G ${formatScore(round.gold_score, 2)}`;
    scores.append(proxy, gold);
    const delta = index ? Number(round.gold_score) - Number(rounds[index - 1].gold_score) : 0;
    const change = document.createElement("div");
    change.className = `round-button-delta ${deltaClass(delta)}`.trim();
    change.textContent = index ? `${formatSigned(delta, 2)} gold` : "initial state";
    button.append(top, scores, change);
    button.addEventListener("click", () => setActiveRound(index));
    track.appendChild(button);
  });
  updateRoundControls(rounds.length);
}

function updateRoundControls(length) {
  byId("previous-round").disabled = state.activeRound <= 0;
  byId("next-round").disabled = state.activeRound >= length - 1;
}

function setActiveRound(index) {
  const rounds = state.payload?.rounds || [];
  if (!rounds.length) return;
  state.activeRound = Math.max(0, Math.min(index, rounds.length - 1));
  renderRoundTrack(rounds);
  renderRoundDetail(rounds);
  renderHistory(rounds);
}

function roundBadges(round) {
  const fragment = document.createDocumentFragment();
  if (round.selected_final) fragment.appendChild(badge("Returned representative", "selected"));
  if (Number(round.selection_weight || 0) > 0) {
    const ties = (state.payload?.rounds || []).filter((item) => Number(item.selection_weight || 0) > 0).length;
    fragment.appendChild(badge(ties > 1 ? `Reward weight ${formatScore(round.selection_weight, 3)}` : "Top proxy round", ties > 1 ? "tie" : "selected"));
  }
  if (!round.proxy_valid) fragment.appendChild(badge("Invalid proxy output", "invalid"));
  return fragment;
}

function responseScores(round, previous = null) {
  const container = document.createElement("div");
  container.className = "response-scores";
  const proxy = document.createElement("div");
  proxy.className = "response-score proxy";
  proxy.append(Object.assign(document.createElement("span"), { textContent: "Proxy" }), Object.assign(document.createElement("strong"), { textContent: formatScore(round.proxy_score) }));
  const gold = document.createElement("div");
  gold.className = "response-score gold";
  gold.append(Object.assign(document.createElement("span"), { textContent: "Gold" }), Object.assign(document.createElement("strong"), { textContent: formatScore(round.gold_score) }));
  const delta = previous && finite(round.gold_score) && finite(previous.gold_score) ? Number(round.gold_score) - Number(previous.gold_score) : 0;
  const change = document.createElement("div");
  change.className = `response-score ${previous ? deltaClass(delta) : ""}`.trim();
  change.append(Object.assign(document.createElement("span"), { textContent: previous ? "Gold vs prior" : "Gold change" }), Object.assign(document.createElement("strong"), { textContent: previous ? formatSigned(delta) : "Initial" }));
  container.append(proxy, gold, change);
  return container;
}

function renderRoundDetail(rounds) {
  const index = state.activeRound;
  const current = rounds[index];
  const next = rounds[index + 1] || null;
  if (!current) return;

  const feedback = current.feedback_used || current.feedback || FALLBACK_FEEDBACK;
  const fallback = Boolean(current.feedback_fallback) || (!current.feedback && !current.proxy_valid);
  byId("feedback-eyebrow").textContent = fallback ? "Fallback feedback after invalid judge output" : `Judge feedback for round ${current.round ?? index}`;
  byId("feedback-title").textContent = next ? `Instruction used to generate round ${next.round ?? index + 1}` : "Terminal feedback (no later revision)";
  byId("feedback-text").textContent = feedback;
  byId("feedback-note").textContent = next
    ? "The candidate generator also received the full earlier candidate, feedback, and proxy-score history. Gold rewards were hidden from it."
    : "This feedback was scored and logged, but the configured round limit ended before another candidate was generated.";
  byId("feedback-note").className = `feedback-note${fallback ? " fallback" : ""}`;
  const pills = byId("feedback-score-pills");
  pills.replaceChildren(
    scorePill("Current proxy", formatScore(current.proxy_score), "proxy"),
    scorePill("Current gold", formatScore(current.gold_score), "gold"),
  );
  if (next) {
    pills.append(
      scorePill("Next proxy change", finite(current.proxy_score) && finite(next.proxy_score) ? formatSigned(Number(next.proxy_score) - Number(current.proxy_score)) : "N/A", "proxy"),
      scorePill("Next gold change", formatSigned(Number(next.gold_score) - Number(current.gold_score)), "gold"),
    );
  }

  byId("current-response-title").textContent = `Round ${current.round ?? index}`;
  byId("current-badges").replaceChildren(roundBadges(current));
  const currentScores = responseScores(current, rounds[index - 1] || null);
  currentScores.id = "current-scores";
  document.querySelector(".current-pane .response-scores")?.replaceWith(currentScores);
  renderStructured(byId("current-response"), current.candidate || current.response || "");

  const nextPane = document.querySelector(".next-pane");
  if (next) {
    nextPane.classList.remove("empty");
    byId("next-response-title").textContent = `Round ${next.round ?? index + 1}`;
    byId("next-badges").replaceChildren(roundBadges(next));
    const nextScores = responseScores(next, current);
    nextScores.id = "next-scores";
    document.querySelector(".next-pane .response-scores")?.replaceWith(nextScores);
    renderStructured(byId("next-response"), next.candidate || next.response || "");
  } else {
    nextPane.classList.add("empty");
    byId("next-response-title").textContent = "No subsequent round";
    byId("next-badges").replaceChildren();
    const emptyScores = document.createElement("div");
    emptyScores.className = "response-scores";
    emptyScores.id = "next-scores";
    document.querySelector(".next-pane .response-scores")?.replaceWith(emptyScores);
    renderStructured(byId("next-response"), "The configured round limit was reached, so this feedback did not produce another logged response.");
  }
  updateRoundControls(rounds.length);
}

function renderHistory(rounds) {
  const body = byId("history-body");
  body.replaceChildren();
  rounds.forEach((round, index) => {
    const row = document.createElement("tr");
    if (index === state.activeRound) row.className = "active";
    row.tabIndex = 0;
    row.addEventListener("click", () => setActiveRound(index));
    row.addEventListener("keydown", (event) => {
      if (event.key === "Enter" || event.key === " ") setActiveRound(index);
    });
    const roundCell = document.createElement("td");
    const roundButton = document.createElement("button");
    roundButton.type = "button";
    roundButton.textContent = `Round ${round.round ?? index}`;
    roundCell.appendChild(roundButton);
    const proxy = document.createElement("td");
    proxy.className = "numeric proxy-value";
    proxy.textContent = formatScore(round.proxy_score);
    const gold = document.createElement("td");
    gold.className = "numeric gold-value";
    gold.textContent = formatScore(round.gold_score);
    const changeValue = index ? Number(round.gold_score) - Number(rounds[index - 1].gold_score) : 0;
    const change = document.createElement("td");
    change.className = `numeric ${deltaClass(changeValue)}`.trim();
    change.textContent = index ? formatSigned(changeValue) : "Initial";
    const decision = document.createElement("td");
    decision.textContent = [round.decision, round.preference].filter(Boolean).join(" · ") || "N/A";
    const selection = document.createElement("td");
    selection.textContent = round.selected_final
      ? `Returned${Number(round.selection_weight || 0) < 1 ? ` · weight ${formatScore(round.selection_weight, 3)}` : ""}`
      : Number(round.selection_weight || 0) > 0
        ? `Tie weight ${formatScore(round.selection_weight, 3)}`
        : "";
    const feedback = document.createElement("td");
    feedback.className = "feedback-preview";
    feedback.textContent = round.feedback_used || round.feedback || (round.proxy_valid ? "" : FALLBACK_FEEDBACK);
    row.append(roundCell, proxy, gold, change, decision, selection, feedback);
    body.appendChild(row);
  });
}

function toggleClamp(button, content) {
  const expanded = button.getAttribute("aria-expanded") === "true";
  button.setAttribute("aria-expanded", String(!expanded));
  content.classList.toggle("is-clamped", expanded);
  button.textContent = expanded ? button.dataset.collapsedLabel : button.dataset.expandedLabel;
}

function switchView(view) {
  state.view = view;
  document.querySelectorAll(".tab").forEach((tab) => {
    const active = tab.dataset.view === view;
    tab.classList.toggle("active", active);
    tab.setAttribute("aria-selected", String(active));
  });
  byId("trajectory-view").hidden = view !== "trajectory";
  byId("overview-view").hidden = view !== "overview";
  if (view === "overview") renderOverview();
}

function summaryMetric(summary, ...names) {
  for (const name of names) if (summary && summary[name] !== undefined) return summary[name];
  return null;
}

function renderOverview() {
  const summary = state.index.summary || {};
  const records = state.trajectories;
  const initial = summaryMetric(summary, "initial_gold_mean") ?? mean(records.map((row) => row.initial_gold));
  const selected = summaryMetric(summary, "selected_gold_mean") ?? mean(records.map((row) => row.selected_gold));
  const last = summaryMetric(summary, "last_gold_mean") ?? mean(records.map((row) => row.last_gold));
  const best = summaryMetric(summary, "best_gold_mean", "oracle_best_gold_mean") ?? mean(records.map((row) => row.best_gold));
  const spearman = summaryMetric(summary, "proxy_gold_spearman_mean", "mean_proxy_gold_spearman") ?? mean(records.map((row) => row.proxy_gold_spearman));
  const overview = byId("overview-summary");
  overview.replaceChildren(
    metricCell("Initial gold mean", formatScore(initial), `${records.length} paths`, "gold"),
    metricCell("Selected gold mean", formatScore(selected), "tie-weighted", "gold"),
    metricCell("Selected change", formatSigned(finite(selected) && finite(initial) ? Number(selected) - Number(initial) : null), "vs initial", deltaClass(finite(selected) && finite(initial) ? Number(selected) - Number(initial) : null)),
    metricCell("Last gold mean", formatScore(last), "round 8", "gold"),
    metricCell("Oracle best mean", formatScore(best), "best state per path", "gold"),
    metricCell("Mean rank agreement", formatScore(spearman), "trajectory Spearman", "proxy"),
  );
  renderOutcomeChart(summary);
  renderRoundChart(summary.per_round || summary.rounds || []);
  renderCheckpointTable();
}

function renderOutcomeChart(summary) {
  const supplied = summary.outcome_counts || {};
  const counts = {
    improved: Number(supplied.improved ?? state.trajectories.filter((row) => row.outcome === "improved").length),
    unchanged: Number(supplied.unchanged ?? state.trajectories.filter((row) => row.outcome === "unchanged").length),
    worsened: Number(supplied.worsened ?? state.trajectories.filter((row) => row.outcome === "worsened").length),
  };
  const total = Object.values(counts).reduce((sum, value) => sum + value, 0) || 1;
  const container = byId("outcome-chart");
  container.replaceChildren();
  const bar = document.createElement("div");
  bar.className = "outcome-bar";
  Object.entries(counts).forEach(([name, count]) => {
    const segment = document.createElement("div");
    segment.className = `outcome-segment ${name}`;
    segment.style.width = `${(count / total) * 100}%`;
    const label = document.createElement("span");
    label.textContent = `${name} ${count}`;
    segment.appendChild(label);
    segment.title = `${name}: ${count} (${formatPercent(count / total)})`;
    bar.appendChild(segment);
  });
  const legend = document.createElement("div");
  legend.className = "outcome-legend";
  Object.entries(counts).forEach(([name, count]) => {
    const item = document.createElement("span");
    item.append(document.createTextNode(`${name[0].toUpperCase()}${name.slice(1)}`));
    const strong = document.createElement("strong");
    strong.textContent = `${count} · ${formatPercent(count / total)}`;
    item.appendChild(strong);
    legend.appendChild(item);
  });
  container.append(bar, legend);
}

function svgElement(name, attributes = {}) {
  const element = document.createElementNS("http://www.w3.org/2000/svg", name);
  Object.entries(attributes).forEach(([key, value]) => element.setAttribute(key, String(value)));
  return element;
}

function renderRoundChart(rows) {
  const container = byId("round-chart");
  container.replaceChildren();
  if (!rows.length) {
    const empty = document.createElement("p");
    empty.textContent = "Per-round aggregates were not exported.";
    container.appendChild(empty);
    return;
  }
  const width = 1000;
  const height = 310;
  const left = 54;
  const right = 24;
  const top = 20;
  const bottom = 42;
  const plotWidth = width - left - right;
  const plotHeight = height - top - bottom;
  const x = (index) => left + (rows.length === 1 ? 0 : (index / (rows.length - 1)) * plotWidth);
  const y = (value) => top + (1 - Math.max(0, Math.min(1, Number(value)))) * plotHeight;
  const svg = svgElement("svg", { viewBox: `0 0 ${width} ${height}`, role: "img", "aria-label": "Mean proxy and gold scores by feedback round" });
  [0, 0.25, 0.5, 0.75, 1].forEach((value) => {
    svg.appendChild(svgElement("line", { x1: left, y1: y(value), x2: width - right, y2: y(value), class: "chart-grid" }));
    const label = svgElement("text", { x: left - 10, y: y(value) + 4, "text-anchor": "end", class: "chart-axis-label" });
    label.textContent = value.toFixed(2);
    svg.appendChild(label);
  });
  rows.forEach((row, index) => {
    const label = svgElement("text", { x: x(index), y: height - 16, "text-anchor": "middle", class: "chart-axis-label" });
    label.textContent = `Round ${row.round ?? index}`;
    svg.appendChild(label);
  });
  const proxyValues = rows.map((row) => number(row.proxy_mean ?? row.mean_proxy));
  const goldValues = rows.map((row) => number(row.gold_mean ?? row.mean_gold));
  const makePath = (values) => values.map((value, index) => `${index ? "L" : "M"} ${x(index)} ${y(value)}`).join(" ");
  if (proxyValues.every(finite)) svg.appendChild(svgElement("path", { d: makePath(proxyValues), class: "chart-proxy" }));
  if (goldValues.every(finite)) svg.appendChild(svgElement("path", { d: makePath(goldValues), class: "chart-gold" }));
  proxyValues.forEach((value, index) => {
    if (!finite(value)) return;
    const dot = svgElement("circle", { cx: x(index), cy: y(value), r: 4, class: "chart-dot-proxy" });
    const title = svgElement("title");
    title.textContent = `Round ${rows[index].round ?? index}: proxy ${formatScore(value)}`;
    dot.appendChild(title);
    svg.appendChild(dot);
  });
  goldValues.forEach((value, index) => {
    if (!finite(value)) return;
    const dot = svgElement("circle", { cx: x(index), cy: y(value), r: 4, class: "chart-dot-gold" });
    const title = svgElement("title");
    title.textContent = `Round ${rows[index].round ?? index}: gold ${formatScore(value)}`;
    dot.appendChild(title);
    svg.appendChild(dot);
  });
  container.appendChild(svg);
}

function checkpointStatistics(checkpoint) {
  const records = state.trajectories.filter((record) => checkpointId(record) === checkpoint.id);
  return {
    count: records.length,
    initial: checkpoint.initial_gold_mean ?? mean(records.map((row) => row.initial_gold)),
    selected: checkpoint.selected_gold_mean ?? mean(records.map((row) => row.selected_gold)),
    best: checkpoint.best_gold_mean ?? checkpoint.oracle_best_gold_mean ?? mean(records.map((row) => row.best_gold)),
  };
}

function renderCheckpointTable() {
  const body = byId("checkpoint-body");
  body.replaceChildren();
  state.checkpoints.forEach((checkpoint) => {
    const stats = checkpointStatistics(checkpoint);
    const row = document.createElement("tr");
    row.addEventListener("click", () => {
      byId("checkpoint-select").value = checkpoint.id;
      applyTrajectoryFilter();
      switchView("trajectory");
      loadSelectedTrajectory();
    });
    const cells = [
      checkpoint.step,
      checkpoint.title || checkpoint.context_label || checkpoint.uid,
      stats.count,
      formatScore(stats.initial),
      formatScore(stats.selected),
      formatScore(stats.best),
    ];
    cells.forEach((value, index) => {
      const cell = document.createElement("td");
      cell.textContent = String(value ?? "N/A");
      if (index >= 2) cell.className = "numeric";
      row.appendChild(cell);
    });
    body.appendChild(row);
  });
}

function moveTrajectory(offset) {
  const current = state.visible.findIndex((record) => trajectoryId(record) === byId("trajectory-select").value);
  const next = Math.max(0, Math.min(current + offset, state.visible.length - 1));
  if (next === current || !state.visible[next]) return;
  byId("trajectory-select").value = trajectoryId(state.visible[next]);
  loadSelectedTrajectory();
}

function refreshIcons() {
  if (window.lucide && typeof window.lucide.createIcons === "function") window.lucide.createIcons();
}

function bindEvents() {
  document.querySelectorAll(".tab").forEach((tab) => tab.addEventListener("click", () => switchView(tab.dataset.view)));
  byId("checkpoint-select").addEventListener("change", () => {
    applyTrajectoryFilter();
    loadSelectedTrajectory();
  });
  byId("outcome-select").addEventListener("change", () => {
    applyTrajectoryFilter();
    loadSelectedTrajectory();
  });
  byId("trajectory-select").addEventListener("change", loadSelectedTrajectory);
  byId("previous-trajectory").addEventListener("click", () => moveTrajectory(-1));
  byId("next-trajectory").addEventListener("click", () => moveTrajectory(1));
  byId("previous-round").addEventListener("click", () => setActiveRound(state.activeRound - 1));
  byId("next-round").addEventListener("click", () => setActiveRound(state.activeRound + 1));
  byId("context-toggle").addEventListener("click", () => toggleClamp(byId("context-toggle"), byId("context-text")));
  byId("rubric-toggle").addEventListener("click", () => toggleClamp(byId("rubric-toggle"), byId("rubric-text")));
  document.addEventListener("keydown", (event) => {
    if (state.view !== "trajectory" || ["INPUT", "SELECT", "TEXTAREA", "SUMMARY"].includes(document.activeElement?.tagName)) return;
    if (event.key === "ArrowLeft") setActiveRound(state.activeRound - 1);
    if (event.key === "ArrowRight") setActiveRound(state.activeRound + 1);
  });
}

async function initialize() {
  bindEvents();
  refreshIcons();
  try {
    const response = await fetch("data/index.json");
    if (!response.ok) throw new Error(`HTTP ${response.status}`);
    state.index = await response.json();
    state.trajectories = state.index.trajectories || state.index.records || [];
    if (!state.trajectories.length) throw new Error("the snapshot contains no trajectories");
    byId("page-title").textContent = state.index.title || "Feedback trajectories";
    byId("strategy-label").textContent = state.index.strategy || "self_reflection_best";
    const counts = state.index.counts || {};
    byId("dataset-count").textContent = `${counts.trajectories || state.trajectories.length} trajectories · ${counts.checkpoints || new Set(state.trajectories.map(checkpointId)).size} checkpoint examples`;
    buildCheckpointIndex();
    populateCheckpointSelect();
    applyTrajectoryFilter();
    renderOverview();
    await loadSelectedTrajectory();
  } catch (error) {
    showError(`Could not load the feedback snapshot (${error.message}).`);
  }
}

initialize();