"use client";

import React, { useState, useRef, useEffect, useMemo } from "react";
import DiagnosticsView from "@/components/diagnostics-view";
import GraphUpdateView from "@/components/graph-update-view";
import SituationGraphView from "@/components/situation-graph-view";
import InvestigationSummaryPanel from "@/components/investigation-summary-panel";
import InvestigationSummaryPanelV2 from "@/components/investigation-summary-panel-v2";
import InvestigationSummaryPanelV3 from "@/components/investigation-summary-panel-v3";
import InvestigationMap from "@/components/investigation-map";

// ── Technical summary detector (main view filters these) ───
const TECHNICAL_PATTERNS = [
  /nodes?\s*[:\d]/i,
  /edges?\s*[:\d]/i,
  /\b(?:unknown|observation|conclusion)\b\s/i,
  /\bsorted\b/i,
  /by_kind/i,
  /\b(?:node|edge|unknown|state)\s+count/i,
];

function isTechnicalSummary(summary) {
  if (!summary || typeof summary !== "string") return false;
  const trimmed = summary.trim();
  if (!trimmed) return false;
  for (const p of TECHNICAL_PATTERNS) {
    if (p.test(trimmed)) return true;
  }
  return false;
}

// ── Recovery state components (Phase 2) ───────────────────────

function ProviderUnavailableCard({ onRestart }) {
  return (
    <div className="rounded-lg border border-amber-300 bg-amber-50 px-5 py-6 text-center">
      <h2 className="mb-1 text-sm font-bold uppercase tracking-wide text-amber-700">Provider unavailable</h2>
      <p className="text-sm text-amber-800 mb-4">
        The reasoning service could not be reached. This is usually temporary — check that the local model is running and try again.
      </p>
      {onRestart && (
        <button
          onClick={onRestart}
          className="rounded-lg border border-amber-300 bg-white px-4 py-2 text-sm font-medium text-amber-800 hover:bg-amber-100"
        >
          Restart investigation
        </button>
      )}
    </div>
  );
}

function MalformedResponseCard({ onRestart }) {
  return (
    <div className="rounded-lg border border-orange-300 bg-orange-50 px-5 py-6 text-center">
      <h2 className="mb-1 text-sm font-bold uppercase tracking-wide text-orange-700">Unexpected response</h2>
      <p className="text-sm text-orange-800 mb-4">
        The reasoning service returned a response we could not interpret. This may indicate a temporary issue with the model output format.
      </p>
      {onRestart && (
        <button
          onClick={onRestart}
          className="rounded-lg border border-orange-300 bg-white px-4 py-2 text-sm font-medium text-orange-800 hover:bg-orange-100"
        >
          Try again
        </button>
      )}
    </div>
  );
}

function UnexpectedStateCard({ stateName, onRetry, onRestart }) {
  return (
    <div className="rounded-lg border border-red-300 bg-red-50 px-5 py-6 text-center">
      <h2 className="mb-1 text-sm font-bold uppercase tracking-wide text-red-700">Unexpected state</h2>
      <p className="text-sm text-red-800 mb-4">
        {stateName ? `The system is in an unexpected state (${stateName}).` : "An unexpected internal error occurred."}
        Please restart the investigation to continue.
      </p>
      <div className="flex items-center justify-center gap-3">
        {onRetry && (
          <button
            onClick={onRetry}
            className="rounded-lg border border-red-300 bg-white px-4 py-2 text-sm font-medium text-red-800 hover:bg-red-100"
          >
            Retry update
          </button>
        )}
        {onRestart && (
          <button
            onClick={onRestart}
            className="rounded-lg bg-red-700 px-4 py-2 text-sm font-medium text-white hover:bg-red-600"
          >
            Restart investigation
          </button>
        )}
      </div>
    </div>
  );
}

function ContinueLaterBanner({ onRestart }) {
  return (
    <div className="rounded-lg border border-blue-200/60 bg-blue-50/40 px-5 py-4 text-center">
      <p className="text-sm text-blue-700/70">
        Your previous investigation state is still saved. You can continue where you left off or start fresh.
      </p>
      {onRestart && (
        <button
          onClick={onRestart}
          className="mt-2 text-sm font-medium text-blue-700 underline hover:text-blue-900"
        >
          Restart investigation
        </button>
      )}
    </div>
  );
}

// ── Session persistence hook (Phase 3) ────────────────────────

function useSessionPersistence() {
  const [sessionReady, setSessionReady] = useState(false);
  const sessionKey = "confidence-engine-session";

  function saveSession(state) {
    if (typeof sessionStorage === "undefined") return;
    try {
      sessionStorage.setItem(sessionKey, JSON.stringify(state));
    } catch (_) { /* quota or disabled — ignore silently */ }
  }

  function loadSession() {
    if (typeof sessionStorage === "undefined") return null;
    try {
      const raw = sessionStorage.getItem(sessionKey);
      return raw ? JSON.parse(raw) : null;
    } catch (_) {
      return null;
    }
  }

  function clearSession() {
    if (typeof sessionStorage === "undefined") return;
    try { sessionStorage.removeItem(sessionKey); } catch (_) {}
  }

  return { saveSession, loadSession, clearSession, sessionReady: true };
}

// ── Shared focused-question body (extracted from OpenQuestionsPanel) ──

function FocusedQuestionBody({
  nodeId,
  isFocused,
  hasCompletedInvestigation: hasCompleted,
  focused,
  formulationStep,
  formulateMsg,
  processingStep,
  deconstructMsg,
  focusedAnswer,
  handleDeconstructSubmit,
  retryFormulation,
  setFocusedAnswer,
  setSelectedPresentationItemId,
  setFocusedPresentationItemId,
  setDoneForNowIds,
  setFollowUpQuestion,
  focusedContributions,
  currentFindings,
  onUpdateFindingDisposition,
  onUpdateFindingProposition,
}) {
  const hasContent = focused?.question?.trim() || formulationStep === "active" || processingStep === "active" || focused?.error;
  const hasResult = Boolean(focused?.result);

  // ── Local correction state (FQB-owned, not propagated upward) ─
  const [editingFindingId, setEditingFindingId] = useState(null);
  const [draft, setDraft] = useState("");

  function startEditing(id, proposition) {
    setEditingFindingId(id);
    setDraft(proposition ?? "");
  }

  function cancelEditing() {
    setEditingFindingId(null);
    setDraft("");
  }

  function saveEditing() {
    const trimmed = (draft ?? "").trim();
    if (!trimmed || !editingFindingId) {
      cancelEditing();
      return;
    }
    onUpdateFindingProposition?.(editingFindingId, trimmed);
    cancelEditing();
  }

  return (
    <>
      {isFocused && hasContent && (
        <div className="mt-4 space-y-4">
          <div className="space-y-4 rounded-lg border border-gray-200 bg-white p-5">
            {focused?.question?.trim() ? (
              <div>
                <h3 className="mb-1 text-[11px] font-semibold tracking-widest uppercase text-gray-500">Question</h3>
                <p className="text-base font-medium leading-relaxed text-gray-900">{focused.question}</p>
              </div>
            ) : formulationStep === "active" ? (
              <p className="text-sm text-blue-600/70">{formulateMsg}</p>
            ) : null}

            {focused?.question?.trim() && processingStep !== "active" && focused.status === "formulated" && (
              <div>
                <label htmlFor={`rw-answer-${nodeId}`} className="mb-2 block text-sm font-medium text-gray-700">Your response</label>
                <textarea id={`rw-answer-${nodeId}`} value={focusedAnswer} onChange={(e) => setFocusedAnswer(e.target.value)} rows={4} data-testid="response-textarea" className="w-full rounded-lg border border-gray-300 px-4 py-3 text-sm focus:border-gray-500 focus:outline-none focus:ring-2 focus:ring-gray-400 disabled:cursor-not-allowed disabled:opacity-60" placeholder="What do you know about this?" />
                <button onClick={(e) => { e.stopPropagation(); handleDeconstructSubmit(nodeId, focusedAnswer); }} disabled={!focusedAnswer.trim() || processingStep === "active"} style={{ cursor: !focusedAnswer.trim() || processingStep === "active" ? "not-allowed" : "pointer" }} className="mt-3 rounded-lg border border-green-600 bg-white px-4 py-2 text-sm font-medium text-green-700 hover:bg-green-50 transition disabled:opacity-50">Submit response</button>
              </div>
            )}

            {processingStep === "active" && <p className="text-sm text-blue-600/70">{deconstructMsg}</p>}

            {focused?.result && (
              <>
                {/* Prior accumulated learning (prior turns, current turn excluded — shown above) */}
                <PriorContributionsSummary nodeId={nodeId} contributions={focusedContributions || []} />

                <div><h3 className="mb-1 text-[11px] font-semibold tracking-widest uppercase text-gray-500">What this tells us</h3><ul className="list-disc pl-5 space-y-2">{(currentFindings?.length ? currentFindings : (focused.result.observations || [])).map((item, i) => {
                  const isFinding = typeof item === "object" && item !== null && "id" in item;
                  const disposition = isFinding ? item.userDisposition : null;
                  const isEditing = isFinding && editingFindingId === item.id;
                  if (!isFinding) {
                    return (
                      <li key={i} className="text-sm leading-relaxed text-gray-700">{item}</li>
                    );
                  }
                  if (isEditing) {
                    return (
                      <li key={i} className="text-sm leading-relaxed text-gray-700 flex items-start gap-2">
                        <textarea
                          value={draft}
                          onChange={(e) => setDraft(e.target.value)}
                          rows={2}
                          data-testid="proposition-editor"
                          className="flex-1 rounded border border-blue-300 bg-blue-50/40 px-2 py-1 text-sm focus:border-blue-400 focus:outline-none focus:ring-1 focus:ring-blue-300"
                        />
                        <div className="flex gap-1 shrink-0 mt-[2px]">
                          <button onClick={(e) => { e.stopPropagation(); saveEditing(); }} data-testid="proposition-save" className="text-[10px] font-medium text-blue-600 underline shrink-0 hover:text-blue-700">Save</button>
                          <button onClick={(e) => { e.stopPropagation(); cancelEditing(); }} data-testid="proposition-cancel" className="text-[10px] font-medium text-gray-400 underline shrink-0 hover:text-gray-500">Cancel</button>
                        </div>
                      </li>
                    );
                  }
                  return (
                    <li key={i} className="text-sm leading-relaxed text-gray-700 flex items-start gap-2">
                      <span className="flex-1">{item.proposition}</span>
                      {onUpdateFindingProposition && (
                        <button onClick={(e) => { e.stopPropagation(); startEditing(item.id, item.proposition); }} data-testid={`not-quite-${item.id}`} className="mt-[2px] text-[10px] font-medium text-amber-500 underline shrink-0 hover:text-amber-600">Not quite</button>
                      )}
                      {isFinding && onUpdateFindingDisposition && (
                        disposition === "not_relevant" ? (
                          <button onClick={(e) => { e.stopPropagation(); onUpdateFindingDisposition(item.id, null); }} data-testid={`restore-${item.id}`} className="mt-[2px] text-[10px] font-medium text-teal-600 underline shrink-0 hover:text-teal-700" title="Restore to understanding">restore</button>
                        ) : (
                          <button onClick={(e) => { e.stopPropagation(); onUpdateFindingDisposition(item.id, "not_relevant"); }} data-testid={`not-relevant-${item.id}`} className="mt-[2px] text-[10px] font-medium text-gray-400 underline shrink-0 hover:text-red-500" title="Remove from understanding">not relevant</button>
                        )
                      )}
                    </li>
                  );
                })}</ul></div>
                <div><h3 className="mb-1 text-[11px] font-semibold tracking-widest uppercase text-gray-500">Still unclear</h3><ul className="list-disc pl-5 space-y-1">{(focused.result.uncertainties || []).map((u, i) => (<li key={i} className="text-sm leading-relaxed text-gray-700">{u}</li>))}</ul></div>
                <div><h3 className="mb-1 text-[11px] font-semibold tracking-widest uppercase text-gray-500">Questions this raises</h3>
                  {(focused.result.possibleFollowUpQuestions || []).length > 0 ? (
                    <div className="space-y-1 mt-1">
                      {focused.result.possibleFollowUpQuestions.map((q, i) => {
                        const isCurrentQuestion = q === focused?.question;
                        return (
                          <button
                            key={i}
                            onClick={(e) => { if (!isCurrentQuestion) { e.stopPropagation(); setFollowUpQuestion(q); } }}
                            style={{ cursor: isCurrentQuestion ? "default" : "pointer" }}
                            className={`w-full text-left rounded-lg border px-3 py-2.5 text-sm leading-relaxed transition ${
                              isCurrentQuestion
                                ? "border-gray-200 bg-gray-100/60 text-gray-400 cursor-default"
                                : "border-blue-200/60 bg-blue-50/40 text-gray-800 hover:border-blue-300 hover:bg-blue-100/60"
                            }`}
                            data-testid="follow-up-question"
                          >
                            {q}
                            {isCurrentQuestion ? " (current question)" : " → pick this question"}
                          </button>
                        );
                      })}
                    </div>
                  ) : (
                    <p className="text-xs text-gray-400">None yet</p>
                  )}
                </div>
                <div><h3 className="mb-1 text-[11px] font-semibold tracking-widest uppercase text-gray-500">Assumptions</h3><ul className="list-disc pl-5 space-y-1">{(focused.result.assumptions || []).map((a, i) => (<li key={i} className="text-sm leading-relaxed text-gray-700">{a}</li>))}</ul></div>
                <div><h3 className="mb-1 text-[11px] font-semibold tracking-widest uppercase text-gray-500">Connections</h3><ul className="list-disc pl-5 space-y-1">{(focused.result.relationships || []).map((r, i) => (<li key={i} className="text-sm leading-relaxed text-gray-700">{r.from} → {r.to} ({r.type})</li>))}</ul></div>
              </>
            )}

            {focused?.error && processingStep !== "active" && (
              <div className="rounded-md border border-amber-200 bg-amber-50 px-4 py-3 text-sm text-amber-800">We were unable to process your request right now. Please try again later.<button onClick={(e) => { e.stopPropagation(); retryFormulation(); }} className="ml-2 font-medium underline">Retry</button></div>
            )}
          </div>
        </div>
      )}
    </>
  );
}

// ── Persistent navigation controls (overlay-level, outside content grid) ──

function FocusedWorkspaceNavigation({ nodeId, doneForNow, onBackToOpenQuestions, isDoneForNowActive }) {
  const canDoneForNow = Boolean(isDoneForNowActive);
  return (
    <div className="mt-6 flex items-center justify-between gap-4 border-t border-gray-200 pt-5">
      <button
        onClick={(e) => { e.stopPropagation(); onBackToOpenQuestions?.(); }}
        style={{ cursor: "pointer" }}
        className="text-sm text-gray-400 underline hover:text-gray-600 transition whitespace-nowrap"
      >
        Back to open questions
      </button>
      <button
        onClick={(e) => { e.stopPropagation(); doneForNow?.(); }}
        style={{ cursor: canDoneForNow ? "pointer" : "not-allowed" }}
        className={`rounded-lg border px-4 py-2 text-sm font-medium transition whitespace-nowrap ${canDoneForNow ? 'border-gray-300 bg-white text-gray-600 hover:bg-gray-50' : 'border-gray-100 bg-gray-50 text-gray-300'}`}
      >
        Done for now
      </button>
    </div>
  );
}

// ── Current understanding card ────────────────────────────────

// Evidence-limit text that must not appear inside Current understanding
// when the terminal outcome already communicates that state.
const EVIDENCE_LIMIT_PHRASES = [
  "The available evidence has reached its current limit",
  "evidence has reached its current limit",
  "evidence limit reached",
  "has reached its current limit",
];

function resolveCurrentSummary(currentSummary) {
  if (!currentSummary || typeof currentSummary !== "string") return null;
  const trimmed = currentSummary.trim();
  if (!trimmed) return null;

  // Filter out technical graph summaries
  for (const p of TECHNICAL_PATTERNS) {
    if (p.test(trimmed)) return null;
  }

  // Don't show evidence-limit text in Current understanding when
  // the terminal outcome card already communicates that state.
  const lower = trimmed.toLowerCase();
  for (const phrase of EVIDENCE_LIMIT_PHRASES) {
    if (lower.includes(phrase)) return null;
  }

  return trimmed;
}

// ── Status message pools for loading feedback ────────────────
const INITIAL_MESSAGES = [
  { min: 0, text: "Reading your situation" },
  { min: 10, text: "Building a structured understanding" },
  { min: 25, text: "Identifying what is known and still unclear" },
  { min: 45, text: "Selecting the next useful question" },
];

const UPDATE_MESSAGES = [
  { min: 0, text: "Considering your answer" },
  { min: 10, text: "Updating the situation" },
  { min: 25, text: "Checking what changed" },
  { min: 45, text: "Choosing the next question" },
];

function useLoadingStatus(messages, isLoading) {
  const [elapsed, setElapsed] = useState(0);
  const startRef = useRef(null);

  useEffect(() => {
    if (isLoading) {
      startRef.current = Date.now();
      const iv = setInterval(() => {
        setElapsed(Math.floor((Date.now() - startRef.current) / 1000));
      }, 1000);
      return () => clearInterval(iv);
    } else {
      setElapsed(0);
      startRef.current = null;
    }
  }, [isLoading]);

  const currentMessage = useMemo(() => {
    if (!messages || messages.length === 0) return "";
    let msg = messages[0].text;
    for (const m of messages) {
      if (elapsed >= m.min) msg = m.text;
    }
    return msg;
  }, [messages, elapsed]);

  return { elapsed, currentMessage };
}

// ── Spinner component ───────────────────────────────────────
function ActivitySpinner() {
  return (
    <span
      className="inline-block h-4 w-4 border-[2px] border-gray-300 border-t-gray-600 rounded-full"
      style={{ animation: "spin 1s linear infinite" }}
    />
  );
}

// ── Current investigation card (prominent hero section) ──────
function CurrentInvestigationCard({ selectedQuestion, graph }) {
  if (!selectedQuestion) return null;

  const q = typeof selectedQuestion === "string" ? selectedQuestion : selectedQuestion.question;
  if (!q) return null;

  // Derive meaningful context from the active node only when it adds value
  let whyMattersText = null;
  if (graph?.activeUnknownNodeId && graph.nodes) {
    const activeNode = graph.nodes.find((n) => n.id === graph.activeUnknownNodeId);
    if (activeNode?.description && activeNode.description !== activeNode.label) {
      whyMattersText = activeNode.description;
    }
  }

  return (
    <div className="investigation-card rounded-lg border-[2.5px] border-green-400 bg-gradient-to-b from-green-50 to-white p-8 shadow-sm">
      <h2 className="mb-3 text-xs font-bold tracking-widest uppercase text-green-600/70">
        Investigation
      </h2>
      <p className="text-2xl font-semibold leading-tight text-gray-900">{q}</p>
      {whyMattersText && (
        <p className="mt-5 text-sm leading-relaxed text-green-800/80">
          {whyMattersText}
        </p>
      )}
    </div>
  );
}

// ── Outcome helpers ───────────────────────────────────────────

function hasGenuineCompletion(graph) {
  if (!graph || !graph.nodes?.length) return false;
  const resolvedIds = new Set(graph.resolvedNodeIds || []);
  const unresolvedCount = graph.nodes.filter(
    (n) => n.kind === "unknown" && n.status !== "resolved" && !resolvedIds.has(n.id),
  ).length;
  if (unresolvedCount > 0) return false;
  if (graph.activeUnknownNodeId) {
    const active = graph.nodes.find((n) => n.id === graph.activeUnknownNodeId);
    if (active && active.status !== "resolved" && !resolvedIds.has(active.id)) return false;
  }
  return true;
}

// ── Completion card (terminal state when all unknowns resolved) ─
function CompletionCard({ summary }) {
  return (
    <div className="rounded-lg border border-green-300 bg-green-50 px-5 py-6 text-center">
      <h2 className="mb-1 text-sm font-bold uppercase tracking-wide text-green-700">Investigation complete</h2>
      <p className="text-base text-gray-800 mb-3">The available evidence supports the following understanding.</p>
      {summary && (
        <div className="mt-4 text-left rounded-md bg-white/60 px-4 py-3 border border-green-100">
          <p className="text-sm leading-relaxed text-gray-700">{summary}</p>
        </div>
      )}
    </div>
  );
}

// ── Evidence-limit card (terminal state: no next question) ───────
function EvidenceLimitCard({ summary }) {
  return (
    <div className="rounded-lg border border-gray-200 bg-gray-50 px-5 py-6 text-center">
      <h2 className="mb-1 text-sm font-bold uppercase tracking-wide text-gray-500">Current evidence limit reached</h2>
      {summary && (
        <div className="mt-4 text-left rounded-md bg-white/60 px-4 py-3 border border-gray-100">
          <p className="text-sm leading-relaxed text-gray-700">{summary}</p>
        </div>
      )}
      <p className="mt-3 text-base text-gray-700">Further progress requires additional evidence.</p>
    </div>
  );
}

// ── Prior contribution summary (embedded within FocusedQuestionBody) ───

function PriorContributionsSummary({ nodeId, contributions }) {
  const threadContribs = contributions.filter((c) => c.targetNodeId === nodeId);
  if (!threadContribs.length) return null;

  // Exclude the most recent contribution — it is already shown as the current result above.
  const priorContribs = threadContribs.slice(0, -1);
  if (!priorContribs.length) return null;

  return (
    <div className="rounded-lg border border-gray-200/60 bg-gray-50/40 px-4 py-3">
      <h4 className="mb-1 text-[11px] font-semibold tracking-widest uppercase text-gray-500">
        Previous learning
      </h4>
      {priorContribs.map((c, idx) => (
        <details key={c.id || idx} className="mb-2 border-b border-gray-200/40 last:border-0 pb-2 last:pb-0" open={idx === 0}>
          <summary className="cursor-pointer text-xs font-medium text-gray-500 hover:text-gray-700 select-none py-1">
            Turn {c.sequence || idx + 1} — contribution ({c.observations?.length ?? 0} observations, {c.uncertainties?.length ?? 0} unclear)
          </summary>
          <div className="pt-2 space-y-3">
            {c.observations?.length ? (
              <div>
                <h5 className="text-[10px] font-semibold tracking-widest uppercase text-gray-500">What this tells us</h5>
                <ul className="list-disc pl-5 space-y-0.5">
                  {c.observations.map((o, i) => (
                    <li key={i} className="text-xs leading-relaxed text-gray-700">{o}</li>
                  ))}
                </ul>
              </div>
            ) : null}
            {c.uncertainties?.length ? (
              <div>
                <h5 className="text-[10px] font-semibold tracking-widest uppercase text-gray-500">Still unclear</h5>
                <ul className="list-disc pl-5 space-y-0.5">
                  {c.uncertainties.map((u, i) => (
                    <li key={i} className="text-xs leading-relaxed text-gray-700">{u}</li>
                  ))}
                </ul>
              </div>
            ) : null}
          </div>
        </details>
      ))}
    </div>
  );
}

// ── Standalone previous learning block (for two-column secondary placement) ───

function SecondaryPreviousLearning({ nodeId, contributions }) {
  const threadContribs = contributions.filter((c) => c.targetNodeId === nodeId);
  if (!threadContribs.length) return null;

  // Exclude the most recent contribution — it is already shown as the current result above.
  const priorContribs = threadContribs.slice(0, -1);
  if (!priorContribs.length) return null;

  return (
    <div className="rounded-lg border border-gray-200/60 bg-gray-50/40 px-4 py-3">
      <h4 className="mb-1 text-[11px] font-semibold tracking-widest uppercase text-gray-500">
        Previous learning
      </h4>
      {priorContribs.map((c, idx) => (
        <details key={c.id || idx} className="mb-2 border-b border-gray-200/40 last:border-0 pb-2 last:pb-0" open={idx === 0}>
          <summary className="cursor-pointer text-xs font-medium text-gray-500 hover:text-gray-700 select-none py-1">
            Turn {c.sequence || idx + 1} — contribution ({c.observations?.length ?? 0} observations, {c.uncertainties?.length ?? 0} unclear)
          </summary>
          <div className="pt-2 space-y-3">
            {c.observations?.length ? (
              <div>
                <h5 className="text-[10px] font-semibold tracking-widest uppercase text-gray-500">What this tells us</h5>
                <ul className="list-disc pl-5 space-y-0.5">
                  {c.observations.map((o, i) => (
                    <li key={i} className="text-xs leading-relaxed text-gray-700">{o}</li>
                  ))}
                </ul>
              </div>
            ) : null}
            {c.uncertainties?.length ? (
              <div>
                <h5 className="text-[10px] font-semibold tracking-widest uppercase text-gray-500">Still unclear</h5>
                <ul className="list-disc pl-5 space-y-0.5">
                  {c.uncertainties.map((u, i) => (
                    <li key={i} className="text-xs leading-relaxed text-gray-700">{u}</li>
                  ))}
                </ul>
              </div>
            ) : null}
          </div>
        </details>
      ))}
    </div>
  );
}

// ── Thread contributions badge (standalone — used outside focused body) ───

function ThreadContributionsBadge({ nodeId, contributions }) {
  const threadContribs = contributions.filter((c) => c.targetNodeId === nodeId);
  if (!threadContribs.length) return null;

  // Show most recent contribution summary inline
  const latest = threadContribs[threadContribs.length - 1];

  const nonEmptyGroups = [];
  for (const key of ["observations", "uncertainties", "assumptions", "relationships"]) {
    const arr = latest[key];
    if (Array.isArray(arr) && arr.length > 0) nonEmptyGroups.push(key);
  }

  return (
    <div className="mt-3">
      {/* Thread learning indicator — collapsed by default; user can expand to inspect history */}
      <details open={false} className="rounded-lg border border-gray-200/80 bg-white/60">
        <summary className="cursor-pointer px-3 py-1.5 text-xs font-medium text-gray-600 hover:text-gray-800 select-none">
          📝 {threadContribs.length} learned contribution{threadContribs.length !== 1 ? "s" : ""}
        </summary>
        <div className="px-3 pb-3 pt-1 space-y-4">
          {/* All contributions listed in order */}
          {threadContribs.map((c, idx) => (
            <div key={c.id || idx} className="space-y-2">
              {idx > 0 && <div className="text-[9px] text-gray-400 tracking-wider uppercase mt-3">Contribution #{c.sequence || idx + 1}</div>}
              {/* What this tells us */}
              {c.observations?.length ? (
                <div>
                  <h4 className="text-[10px] font-semibold tracking-widest uppercase text-gray-500">What this tells us</h4>
                  <ul className="list-disc pl-5 space-y-0.5">
                    {c.observations.map((o, i) => (
                      <li key={i} className="text-xs leading-relaxed text-gray-700">{o}</li>
                    ))}
                  </ul>
                </div>
              ) : null}

              {/* Still unclear */}
              {c.uncertainties?.length ? (
                <div>
                  <h4 className="text-[10px] font-semibold tracking-widest uppercase text-gray-500">Still unclear</h4>
                  <ul className="list-disc pl-5 space-y-0.5">
                    {c.uncertainties.map((u, i) => (
                      <li key={i} className="text-xs leading-relaxed text-gray-700">{u}</li>
                    ))}
                  </ul>
                </div>
              ) : null}

              {/* Assumptions */}
              {c.assumptions?.length ? (
                <div>
                  <h4 className="text-[10px] font-semibold tracking-widest uppercase text-gray-500">Assumptions</h4>
                  <ul className="list-disc pl-5 space-y-0.5">
                    {c.assumptions.map((a, i) => (
                      <li key={i} className="text-xs leading-relaxed text-gray-700">{a}</li>
                    ))}
                  </ul>
                </div>
              ) : null}

              {/* Connections */}
              {c.relationships?.length ? (
                <div>
                  <h4 className="text-[10px] font-semibold tracking-widest uppercase text-gray-500">Connections</h4>
                  <ul className="list-disc pl-5 space-y-0.5">
                    {c.relationships.map((r, i) => (
                      <li key={i} className="text-xs leading-relaxed text-gray-700">{r.from} → {r.to} ({r.type})</li>
                    ))}
                  </ul>
                </div>
              ) : null}
            </div>
          ))}
        </div>
      </details>
    </div>
  );
}

// ── Quiet facilitator state (experiment mode) ─────────────────────

function QuietStateCard() {
  return (
    <div className="rounded-lg border border-gray-200/60 bg-gray-50/40 px-5 py-5 text-center">
      <p className="text-sm leading-relaxed text-gray-500 mb-1">
        Nothing more to add here right now
      </p>
      <p className="text-xs leading-relaxed text-gray-400">
        You can continue with another question, switch branches, or return when
        you have more information.
      </p>
    </div>
  );
}

// ── New connection / late-result indicator ────────────────────────

function UpdatedConnectionCard({ update }) {
  return (
    <div className="space-y-2">
      <h2 className="text-[11px] font-semibold tracking-widest uppercase text-gray-500">
        New update
      </h2>
      <div className="rounded-lg border border-blue-200/60 bg-blue-50/40 px-4 py-3">
        <p className="text-sm leading-relaxed text-blue-800/80">{update.text}</p>
      </div>
    </div>
  );
}

// ── Branch notebook content (RTO.27A) ────────────────────────────
// Smallest useful branch-scoped composition from fixture data.
// Only renders sections grounded in existing records.

function BranchNotebookContent({
  branchContext,
  contributions,
  openQuestions,
  lateResults,
  inactiveBranchNewResults,
  doneForNowBranchIds,
  onDoneForNow,
  branchId,
}) {
  const hasOpenItems = openQuestions && openQuestions.length > 0;
  const hasContributions = contributions && contributions.length > 0;
  const isPaused = doneForNowBranchIds?.includes(branchId) || false;
  const isBranchActive = !isPaused;

  return (
    <div className="space-y-6">
      {/* Why this branch exists — origin question is primary */}
      {branchContext && (
        <div className="rounded-lg border border-blue-200/60 bg-blue-50/40 px-5 py-4">
          <h2 className="mb-1 text-[11px] font-semibold tracking-widest uppercase text-gray-500">
            Investigating
          </h2>
          {branchContext.originQuestion ? (
            <>
              <p className="text-base leading-relaxed text-gray-900">{branchContext.originQuestion.text}</p>
              {branchContext.label && branchContext.originQuestion.text !== branchContext.label && (
                <p className="mt-2 text-xs text-gray-500/70">Branch: {branchContext.label}</p>
              )}
            </>
          ) : branchContext.origin ? (
            <>
              <p className="text-base font-medium leading-tight text-gray-900">{branchContext.label}</p>
              <p className="mt-2 text-sm leading-relaxed text-gray-600">
                Trying to understand: {branchContext.origin}
              </p>
            </>
          ) : (
            <p className="text-base font-medium leading-tight text-gray-900">{branchContext.label}</p>
          )}
        </div>
      )}

      {/* What we know here */}
      {hasContributions && (
        <div className="space-y-2">
          <h2 className="text-[11px] font-semibold tracking-widest uppercase text-gray-500">
            What we know here
          </h2>
          <div className="space-y-2">
            {contributions.map((c, i) => (
              <div key={i} className="rounded-lg border border-gray-200/80 bg-gray-50/60 px-4 py-3">
                <p className="text-sm leading-relaxed text-gray-700">{c.text}</p>
              </div>
            ))}
          </div>
        </div>
      )}

      {/* Still uncertain here */}
      {hasOpenItems && (
        <div className="space-y-2">
          <h2 className="text-[11px] font-semibold tracking-widest uppercase text-gray-500">
            Still uncertain / open questions
          </h2>
          <div className="space-y-1">
            {openQuestions.map((q, i) => (
              <QuestionRow key={q.id} question={q} />
            ))}
          </div>
        </div>
      )}

      {/* New connection / updates (active branch) */}
      {lateResults && lateResults.length > 0 && (
        <UpdatedConnectionCard update={lateResults[0]} />
      )}

      {/* Done for now control — only when branch is not already paused */}
      {isBranchActive && onDoneForNow && contributions.length > 0 && (
        <div className="flex justify-end pt-1">
          <button
            onClick={(e) => { e.stopPropagation(); onDoneForNow(); }}
            style={{ cursor: "pointer" }}
            className="rounded-lg border border-gray-300 bg-white px-4 py-2 text-sm font-medium text-gray-600 hover:bg-gray-50 transition whitespace-nowrap"
          >
            Done for now
          </button>
        </div>
      )}

      {/* Quiet state */}
      {!hasOpenItems && !lateResults?.length && (
        <div className="rounded-lg border border-gray-200/60 bg-gray-50/40 px-5 py-5 text-center">
          {isPaused ? (
            <>
              <p className="text-sm leading-relaxed text-gray-500 mb-1">
                Nothing more to add here right now
              </p>
              <p className="text-xs leading-relaxed text-gray-400">
                This branch is paused. Reasoning preserved — return when you have more information.
              </p>
            </>
          ) : (
            <QuietStateCard />
          )}
        </div>
      )}
    </div>
  );
}

// ── Question row (renders clickable card with optional focused content) ─

function QuestionRow({ question }) {
  const [isFocused, setIsFocused] = useState(false);

  if (!isFocused) {
    return (
      <button
        onClick={() => setIsFocused(true)}
        style={{ cursor: "pointer" }}
        className="w-full text-left rounded-lg border border-gray-200 px-4 py-3 transition hover:border-gray-300 hover:bg-white"
      >
        <p className="text-sm leading-snug text-gray-600">{question.label}</p>
      </button>
    );
  }

  return (
    <div className="rounded-lg border border-gray-200 bg-white px-4 py-4 space-y-3">
      <p className="text-sm font-medium text-gray-900 leading-snug">{question.label}</p>
      <div className="space-y-2">
        <p className="text-sm leading-relaxed text-gray-500">
          We have not explored this yet. Do you want to work through it?
        </p>
        <button
          onClick={(e) => {
            e.stopPropagation();
            // Placeholder — production would call API for focused investigation
          }}
          style={{ cursor: "pointer" }}
          className="rounded-lg border border-blue-600 bg-white px-4 py-2 text-sm font-medium text-blue-700 hover:bg-blue-50 transition"
        >
          Work through this
        </button>
      </div>
      <button
        onClick={() => setIsFocused(false)}
        style={{ cursor: "pointer" }}
        className="text-xs text-gray-400 underline hover:text-gray-600 transition"
      >
        Back to open questions
      </button>
    </div>
  );
}

// ── Current understanding card ────────────────────────────────
function CurrentUnderstandingCard({ currentSummary, plainLanguage }) {
  if (plainLanguage) return <PlainLanguageCard summary={plainLanguage} />;

  const summary = resolveCurrentSummary(currentSummary);

  if (!summary) return null;

  return (
    <div className="rounded-lg border-[2.5px] border-teal-300/60 bg-gradient-to-b from-teal-50/40 to-white px-7 pt-6 pb-7">
      <h2 className="mb-3 text-[11px] font-bold tracking-widest uppercase text-teal-700/60">
        Understanding
      </h2>
      <p className="text-base leading-relaxed text-gray-800">{summary}</p>
    </div>
  );
}

// ── Plain-language understanding card (from pipeline summary) ──
function PlainLanguageCard({ summary }) {
  if (!summary) return null;

  return (
    <div className="rounded-lg border-[2.5px] border-teal-300/60 bg-gradient-to-b from-teal-50/40 to-white px-7 pt-6 pb-7">
      <h2 className="mb-3 text-[11px] font-bold tracking-widest uppercase text-teal-700/60">
        Understanding
      </h2>
      <p className="text-base leading-relaxed text-gray-800">{summary}</p>
    </div>
  );
}

// ── Investigation history card (readable notebook style) ──────
function InvestigationHistoryCard({ turn }) {
  const isCollapsed = turn._collapsed;
  const isAnswered = Boolean(turn.answer?.trim());

  const displayedQuestion = turn.question;

  return (
    <details
      className="rounded-lg border border-gray-200/60 bg-gray-50/30"
      key={turn.id}
      open={!isCollapsed}
      data-testid="investigation-turn"
    >
      <summary className="cursor-pointer px-4 py-2 text-sm font-medium text-gray-700 hover:text-gray-900">
        {isAnswered && <span aria-hidden="true">✓ </span>}
        {displayedQuestion}
      </summary>

      <div className="space-y-2 px-4 pb-4 pt-2">
        <p className="text-gray-700">{turn.answer}</p>

        {turn.acknowledgement && (
          <p className="italic text-gray-500">
            {turn.acknowledgement}
          </p>
        )}
      </div>
    </details>
  );
}

// ── Investigation history section ─────────────────────────────
function InvestigationHistory({ turns }) {
  if (!turns || turns.length === 0) return null;

  const latestId = turns[turns.length - 1].id;

  return (
    <div className="space-y-3" data-testid="investigation-history">
      <h2 className="text-[11px] font-semibold tracking-widest uppercase text-gray-500">
        History
      </h2>
      <div className="space-y-2">
        {turns.map((turn) => (
          <InvestigationHistoryCard key={turn.id} data-testid="investigation-turn" turn={{ ...turn, _collapsed: turn.id !== latestId }} />
        ))}
      </div>
    </div>
  );
}

// ── Original situation (always-visible reference card) ────────
function OriginalSituation({ scenario, centralStatement }) {
  const text = scenario || centralStatement;

  if (!text) return null;

  return (
    <div className="rounded-lg border border-gray-200/60 bg-gray-50/40 px-5 py-4">
      <h2 className="mb-2 text-[11px] font-semibold tracking-widest uppercase text-gray-500">
        Situation
      </h2>

      <p className="whitespace-pre-wrap text-sm leading-relaxed text-gray-600">
        {text}
      </p>
    </div>
  );
}

// ── Transient acknowledgement (auto-dismisses after 3s) ─────────

function useAutoDismiss(duration = 3000) {
  const [visible, setVisible] = useState(true);

  useEffect(() => {
    if (!visible) return;
    const timer = setTimeout(() => setVisible(false), duration);
    return () => clearTimeout(timer);
  }, [visible, duration]);

  return visible;
}

function UpdateAcknowledgement({ updateResult }) {
  const visible = useAutoDismiss(3000);

  if (!updateResult || !visible) return null;

  const summary = updateResult.summary;

  return (
    <div
      className="transition-all duration-1500 ease-in"
      style={{ opacity: visible ? 0.7 : 0, maxHeight: visible ? "4rem" : "0", marginBottom: visible ? "1rem" : "0" }}
    >
      <div className="rounded-md border border-blue-200/60 bg-blue-50/30 px-4 py-2 text-xs text-blue-700/60">
        {summary}
      </div>
    </div>
  );
}

// ── Developer details disclosure ──────────────────────────────
function DeveloperDetails({ graph, selectedQuestion, diagnostics, newlySurfacedNodeIds, updateResult }) {
  return (
    <details className="rounded-lg border border-gray-200/60 bg-gray-50/30">
      <summary className="cursor-pointer px-5 py-3 text-sm font-medium text-gray-400 hover:text-gray-600">
        Developer details
      </summary>
      <div className="border-t border-gray-200/60 px-5 pb-4 pt-3 space-y-4">
        {graph && (
          <SituationGraphView
            situationGraph={graph}
            selectedQuestion={selectedQuestion}
            newlySurfacedNodeIds={newlySurfacedNodeIds}
          />
        )}
        {updateResult && (
          <GraphUpdateView updateResult={{ ...updateResult, previousSituationGraph: graph }} />
        )}
        {diagnostics && <DiagnosticsView result={{ diagnostics }} />}
      </div>
    </details>
  );
}

// ── Loading overlay (for both start and update) ───────────────
function LoadingOverlay({ isLoading, elapsed, currentMessage, variant }) {
  if (!isLoading) return null;

  const messages = variant === "update" ? UPDATE_MESSAGES : INITIAL_MESSAGES;
  let statusText = messages[0].text;
  for (const m of messages) {
    if (elapsed >= m.min) statusText = m.text;
  }

  return (
    <div className="rounded-lg border border-blue-200/60 bg-blue-50/40 px-6 py-7" role="status" aria-busy="true" data-testid="loading-overlay">
      <div className="flex items-center gap-3">
        <ActivitySpinner />
        <span className="text-base font-medium text-blue-800/70">Working through your situation</span>
      </div>
      <p className="mt-3 text-sm text-blue-600/60">{statusText}</p>
      <p className="mt-2 text-xs text-blue-400/50" aria-live="polite">
        This has been running for {elapsed}s.
        {variant === "initial" && elapsed >= 45 && (
          <span className="block mt-1">This can take around a minute with the current local model.</span>
        )}
      </p>
    </div>
  );
}

// ── Main workspace component ──────────────────────────────────

function getErrorType(errorStr, stage, hasGraph) {
  if (!errorStr && !stage) return null;
  const lower = (errorStr || "").toLowerCase();
  if (/provider|unavailable|network|timeout/.test(lower)) return "provider-unavailable";
  if (/malformed|invalid.*format|parse|structured/.test(lower)) return "malformed-response";
  if (stage === "provider") return "provider-error";
  if (stage === "unexpected") return "unexpected-state";
  if (/validation/.test(lower) && !hasGraph) return "no-graph";
  return null;
}

// ── Focused investigation overlay workspace container ──────────

function FocusedInvestigationWorkspace({
  nodeId,
  focused,
  formulationStep,
  formulateMsg,
  processingStep,
  deconstructMsg,
  focusedAnswer,
  handleDeconstructSubmit,
  retryFormulation,
  setFocusedAnswer,
  setSelectedPresentationItemId,
  setFocusedPresentationItemId,
  setDoneForNowIds,
  setFollowUpQuestion,
  setIsFocusedWorkspaceOpen,
  hasCompletedInvestigation,
  focusedContributions,
  currentFindings,
  onUpdateFindingDisposition,
  onUpdateFindingProposition,
}) {
  const hasResult = Boolean(focused?.result);

  return (
    <div className="mx-auto w-full max-w-[1600px]">
      {/* Two-column responsive grid: primary active work + secondary context */}
      <div className={`grid gap-5 xl:grid-cols-[minmax(0,1.7fr)_minmax(280px,0.8fr)]`}>
        {/* ── Primary column: active investigation — min-w-0 prevents flex growth in single-column mode ── */}
        <div className="min-w-0 overflow-hidden">
          <FocusedQuestionBody
            nodeId={nodeId}
            isFocused={true}
            hasCompletedInvestigation={hasCompletedInvestigation}
            focused={focused}
            formulationStep={formulationStep}
            formulateMsg={formulateMsg}
            processingStep={processingStep}
            deconstructMsg={deconstructMsg}
            focusedAnswer={focusedAnswer}
            handleDeconstructSubmit={handleDeconstructSubmit}
            retryFormulation={retryFormulation}
            setFocusedAnswer={setFocusedAnswer}
            setSelectedPresentationItemId={setSelectedPresentationItemId}
            setFocusedPresentationItemId={setFocusedPresentationItemId}
            setDoneForNowIds={setDoneForNowIds}
            setFollowUpQuestion={setFollowUpQuestion}
            focusedContributions={hasResult ? [] : (focusedContributions || [])}
            currentFindings={currentFindings || []}
            onUpdateFindingDisposition={onUpdateFindingDisposition}
            onUpdateFindingProposition={onUpdateFindingProposition}
          />
        </div>

        {/* ── Secondary context: Previous Learning — visible on all breakpoints, placed in grid column on wide / flows below primary on narrow ── */}
        {hasResult && (
          <SecondaryPreviousLearning nodeId={nodeId} contributions={focusedContributions || []} />
        )}
      </div>
    </div>
  );
}

// ── Open questions panel (production, non-experiment mode) ────────

function OpenQuestionsPanel({
  graph, selectedPresentationItemId, focusedPresentationItemId, hasFocusedContent,
  focused, formulationStep, formulateMsg, processingStep, deconstructMsg, doneForNowIds,
  startFocused, handleDeconstructSubmit, retryFormulation, setSelectedPresentationItemId,
  setFocusedPresentationItemId, setFocusedAnswer, focusedAnswer, setDoneForNowIds,
  setFollowUpQuestion, focusedContributions, focusedInvestigations, setIsFocusedWorkspaceOpen,
  onUpdateFindingDisposition,
  onUpdateFindingProposition,
}) {
  const openNodes = (graph?.nodes || []).filter(
    (n) => n.kind === "unknown" && n.status !== "resolved" && !doneForNowIds.includes(n.id),
  );

  if (openNodes.length <= 0) return null;

  // Check whether a node has a completed focused result stored locally.
  const hasCompletedInvestigation = (nid) => {
    const inv = focusedInvestigations?.[nid];
    return Boolean(inv && inv.status === "formulated" && inv.result && typeof inv.question === "string" && inv.question.trim());
  };

  function handleNodeClick(node) {
    if (hasCompletedInvestigation(node.id) && selectedPresentationItemId === node.id) {
      setFocusedPresentationItemId(node.id);
      return;
    }
    setSelectedPresentationItemId(
      selectedPresentationItemId === node.id ? null : node.id,
    );
  }

  return (
    <div className="space-y-4">
      <h2 className="text-[11px] font-semibold tracking-widest uppercase text-gray-500">
        Open questions
      </h2>
      <div className="space-y-1">
        {openNodes.map((node) => {
          const isSelected = selectedPresentationItemId === node.id;
          const isFocused = focusedPresentationItemId === node.id;

          return (
            <div key={node.id}>
              <div
                onClick={() => handleNodeClick(node)}
                style={{ cursor: "pointer" }}
                className="w-full text-left rounded-lg border border-gray-200 px-4 py-3 transition hover:border-gray-300 hover:bg-white"
              >
                <p className={`leading-snug ${isSelected ? "text-sm font-medium text-gray-900" : "text-sm text-gray-600"}`}>
                  {node.label}
                </p>

                {isSelected && !hasFocusedContent() && (
                  <div className="mt-3 space-y-3">
                    <p className="text-sm leading-relaxed text-gray-500">
                      We have not explored this yet. Do you want to work through it?
                    </p>
                    <button
                      onClick={(e) => { e.stopPropagation(); startFocused(node.id); }}
                      style={{ cursor: "pointer" }}
                      className="rounded-lg border border-blue-600 bg-white px-4 py-2 text-sm font-medium text-blue-700 hover:bg-blue-50 transition"
                    >
                      Work through this
                    </button>
                  </div>
                )}

                <FocusedQuestionBody
                  nodeId={node.id}
                  isFocused={isFocused}
                  hasCompletedInvestigation={() => hasCompletedInvestigation(node.id)}
                  focused={focused}
                  formulationStep={formulationStep}
                  formulateMsg={formulateMsg}
                  processingStep={processingStep}
                  deconstructMsg={deconstructMsg}
                  focusedAnswer={focusedAnswer}
                  handleDeconstructSubmit={handleDeconstructSubmit}
                  retryFormulation={retryFormulation}
                  setFocusedAnswer={setFocusedAnswer}
                  setSelectedPresentationItemId={setSelectedPresentationItemId}
                  setFocusedPresentationItemId={setFocusedPresentationItemId}
                  setDoneForNowIds={setDoneForNowIds}
                  setFollowUpQuestion={setFollowUpQuestion}
                  focusedContributions={focusedContributions}
                  onUpdateFindingDisposition={onUpdateFindingDisposition}
                  onUpdateFindingProposition={onUpdateFindingProposition}
                />

                {/* Thread contributions for this node */}
                <ThreadContributionsBadge nodeId={node.id} contributions={focusedContributions || []} />
              </div>
            </div>
          );
        })}
      </div>

      {doneForNowIds.length > 0 && (
        <div className="pt-3 border-t border-gray-200">
          <h3 className="mb-2 text-[11px] font-semibold tracking-widest uppercase text-gray-500">Done for now</h3>
          <div className="space-y-1">
            {graph.nodes.filter((n) => doneForNowIds.includes(n.id)).map((node) => (
              <div key={node.id} className="rounded-lg border border-gray-200/60 bg-gray-50/40 px-4 py-3 space-y-1">
                <p className="text-sm text-gray-500 leading-snug">{node.label}</p>
                <ThreadContributionsBadge nodeId={node.id} contributions={focusedContributions || []} />
                <button onClick={() => setDoneForNowIds(doneForNowIds.filter(id => id !== node.id))} style={{ cursor: "pointer" }} className="mt-1 rounded border border-gray-300 px-3 py-1 text-xs font-medium text-gray-500 hover:bg-white transition">Reopen</button>
              </div>
            ))}
          </div>
        </div>
      )}
    </div>
  );
}

export default function ReasoningWorkspace({
  scenario,
  status,
  updateStatus,
  currentUnderstanding: propUnderstanding,
  result,
  answer,
  setAnswer,
  onAnswerSubmit,
  lastSubmittedAnswer,
  onRestart,
  focusedContributions,
  onFocusedContribution,
  findings,
  onUpdateFindingDisposition,
  onUpdateFindingProposition,
}) {
  const [investigationHistory, setInvestigationHistory] = useState([]);
  const turnCounter = useRef(0);
  const pendingTurnRef = useRef(null);
  // ── Experiment 12: toggle between progress panel versions (temporary experimental UI) ──
  const [panelVariant, setPanelVariant] = useState("c");

  // ── RTO.01 — presentation-only selection for open investigation items ──
  const [selectedPresentationItemId, setSelectedPresentationItemId] = useState(null);

  // ── RTO.02 — case / question workspace lifecycle (presentation only) ──
  const [focusedPresentationItemId, setFocusedPresentationItemId] = useState(null);
  const [doneForNowIds, setDoneForNowIds] = useState([]);

  // ── Focused investigation overlay workspace ───────────────
  const [isFocusedWorkspaceOpen, setIsFocusedWorkspaceOpen] = useState(false);

  // ── RTO.29D — post-Analyse initial reflection surface ─────────
  const [initialReflectionActive, setInitialReflectionActive] = useState(false);
  const [postAnalyseStatus, setPostAnalyseStatus] = useState(null);

  const { saveSession, loadSession } = useSessionPersistence();

  // Persist workspace state on every successful update (Phase 3)
  useEffect(() => {
    if (updateStatus === "success" && result?.situationGraph) {
      saveSession({
        scenario,
        situationGraph: result.situationGraph,
        selectedQuestion: result.selectedQuestion,
        summary: result.summary || propUnderstanding,
        updatedAt: new Date().toISOString(),
        focusedContributions,
      });
    }
  }, [updateStatus, result, focusedContributions]);

  // Capture the current selected question at submit time (not from a stale ref)
  const capturePendingTurn = (selectedQuestion, answerText) => {
    if (!selectedQuestion || !answerText?.trim()) return null;
    const q = typeof selectedQuestion === "string" ? selectedQuestion : selectedQuestion.question;
    if (!q) return null;
    turnCounter.current += 1;
    return {
      id: `turn-${turnCounter.current}`,
      question: q,
      answer: answerText.trim(),
      acknowledgement: null,
    };
  };

  // Append the captured pending turn to history after a successful update only
  useEffect(() => {
    const pending = pendingTurnRef.current;
    if (!pending || updateStatus !== "success") return;

    setInvestigationHistory((prev) => [
      ...prev,
      { ...pending, acknowledgement: result?.summary || null },
    ]);
    pendingTurnRef.current = null;
  }, [updateStatus, result]);

  const handleUpdateCaptureAndSubmit = async (e) => {
    e.preventDefault();
    if (!answer?.trim() || !result?.selectedQuestion) return;
    pendingTurnRef.current = capturePendingTurn(result.selectedQuestion, answer);
    await onAnswerSubmit(e);
  };

  const graph = result?.situationGraph ?? null;
  const hasGraph = Boolean(graph);

  const diagnostics = result?.diagnostics ?? null;
  const newlySurfacedNodeIds = result?.newlySurfacedNodeIds || [];
  const genuineCompletion = hasGenuineCompletion(graph);

  const errorType = getErrorType(
    result?.error || (result?.updateError ? result.updateError.error : null),
    result?.stage,
    Boolean(graph)
  );

  const isProviderUnavailable =
    errorType === "provider-unavailable" || errorType === "provider-error";
  const isMalformedResponse = errorType === "malformed-response";

  // ── RTO.13B — focused investigation localized state ───────────

  const [formulationStep, setFormulationStep] = useState("idle");
  const [processingStep, setProcessingStep] = useState("idle");

  const { elapsed: startElapsed, currentMessage: startMsg } = useLoadingStatus(
    INITIAL_MESSAGES,
    status === "loading"
  );

  const { elapsed: updateElapsed, currentMessage: updateMsg } = useLoadingStatus(
    UPDATE_MESSAGES,
    updateStatus === "loading"
  );

  // ── RTO.13B — focused investigation loading hooks ─────────────

  const FORMULATING_MESSAGES = [
    { min: 0, text: "Working out a question…" },
    { min: 15, text: "Still working on that question" },
    { min: 30, text: "Formulating the right question for this" },
    { min: 45, text: "A moment longer — this can take around a minute" },
  ];

  const DECONSTRUCT_MESSAGES = [
    { min: 0, text: "Working through your response…" },
    { min: 15, text: "Still working on that response" },
    { min: 30, text: "A moment longer — this can take around a minute" },
  ];

  const { elapsed: formulateElapsed, currentMessage: formulateMsg } = useLoadingStatus(
    FORMULATING_MESSAGES,
    formulationStep === "active",
  );

  const { elapsed: deconstructElapsed, currentMessage: deconstructMsg } = useLoadingStatus(
    DECONSTRUCT_MESSAGES,
    processingStep === "active",
  );

  const isUpdating = updateStatus === "loading";
  const hasSelectedQuestion = Boolean(result?.selectedQuestion);

  // ── RTO.13B — focused investigation localized state (keyed by node ID) ──
  const [focusedInvestigations, setFocusedInvestigations] = useState({});
  const [focusedAnswer, setFocusedAnswer] = useState("");

  // ── Persist focused contributions immediately after deconstruct success ────
  const lastPersistedContribCount = useRef(0);

  useEffect(() => {
    if (!graph) return;
    if (focusedContributions.length === lastPersistedContribCount.current) return;
    lastPersistedContribCount.current = focusedContributions.length;
    saveSession({
      scenario,
      situationGraph: graph,
      selectedQuestion: result?.selectedQuestion,
      summary: result?.summary || propUnderstanding,
      updatedAt: new Date().toISOString(),
      focusedContributions,
    });
  }, [focusedContributions]);

  function getFocusedInvestigation() {
    if (!focusedPresentationItemId) return null;
    return focusedInvestigations[focusedPresentationItemId] || null;
  }

  function focusItem(nodeId) {
    setSelectedPresentationItemId(nodeId);
    setFocusedPresentationItemId(nodeId);
  }

  const focused = getFocusedInvestigation();

  // ── Derive presentation data: exact existing Findings for the current focused Contribution ──
  let currentFindings = [];
  if (focused?.result?.correlationId && findings) {
    const correlationId = focused.result.correlationId;
    const matchedContribution = (focusedContributions || []).find(
      (c) => c.correlationId === correlationId,
    );
    if (matchedContribution) {
      currentFindings = findings.filter(
        (f) => f.contributionId === matchedContribution.id,
      );
    }
  }

  // Gate evidence-limit card: do NOT show when active investigation paths remain.
  const showEvidenceLimit = !(
    processingStep === "active" ||
    (focused?.question?.trim() && !processingStep) ||
    (hasGraph && !genuineCompletion)
  );

  // ── RTO.13B — workflow handlers ──────────────────────────────

  function startFocused(nodeId) {
    const target = nodeId || focusedPresentationItemId;
    if (!target) return;

    const priorContribs = (focusedContributions || []).filter(
      (c) => c.targetNodeId === target,
    );

    setFocusedPresentationItemId(target);
    setFocusedAnswer("");

    // Always open the focused workspace overlay
    setIsFocusedWorkspaceOpen(true);

    if (priorContribs.length > 0) {
      // Reopen path: resume from accumulated contribution history.
      // Do NOT call doFormulate — the user's prior investigation direction
      // is preserved; only follow-up questions surface for explicit selection.
      const latest = priorContribs[priorContribs.length - 1];

      setFocusedInvestigations((prev) => ({
        ...prev,
        [target]: {
          status: "formulated",
          question: latest.question || "",
          answer: latest.answer ?? null,
          result: latest.possibleFollowUpQuestions
            ? {
                observations: latest.observations || [],
                uncertainties: latest.uncertainties || [],
                assumptions: latest.assumptions || [],
                relationships: latest.relationships || [],
                possibleFollowUpQuestions: latest.possibleFollowUpQuestions,
              }
            : null,
          error: null,
        },
      }));

      setFormulationStep("idle");
      return;
    }

    // Fresh thread path — unchanged original behaviour.
    setFormulationStep("active");
    setFocusedInvestigations((prev) => ({
      ...prev,
      [target]: { status: "formulating", question: "", answer: null, result: null, error: null },
    }));
    doFormulate(target);
  }

  async function doFormulate(targetNodeId) {
    const nodeId = targetNodeId || focusedPresentationItemId;
    if (!nodeId || !hasGraph) return;
    try {
      const url = "/api/focused-investigation/formulate";
      const res = await fetch(url, {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ situationGraph: graph, targetNodeId: nodeId }),
      });
      const data = await res.json();
      if (!data.success) throw new Error(data.error || "Formulation failed");

      // Deterministic presentation anchor: explicitly set the focused item to the
      // target node so formulation success always renders correctly.
      setFocusedPresentationItemId(nodeId);

      setFocusedInvestigations((prev) => ({
        ...prev,
        [nodeId]: { ...prev[nodeId], question: data.question, status: "formulated", error: null },
      }));
      setFormulationStep("idle");
    } catch (err) {
      setFocusedInvestigations((prev) => ({
        ...prev,
        [focusedPresentationItemId]: { ...prev[focusedPresentationItemId], question: "", error: err.message || "Formulation failed" },
      }));
    }
  }

  async function handleDeconstructSubmit(targetNodeId, answerText) {
    if (!hasGraph) return;

    const targetNode = graph?.nodes?.find((n) => n.id === targetNodeId);
    const centralStmt = graph?.centralStatement || scenario || "";

    setProcessingStep("active");

    const correlationId = crypto.randomUUID();

    try {
      const url = "/api/focused-investigation/deconstruct";

      const res = await fetch(url, {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({
          targetNodeId: targetNodeId,
          targetLabel: targetNode?.label || "",
          targetDescription: targetNode?.description || "",
          centralStatement: centralStmt,
          question: focused.question,
          answer: answerText,
        }),
      });

      const data = await res.json();

      if (!data.success) throw new Error(data.error || "Deconstruction failed");

      // Persist contribution to case-level owner (ScenarioForm)
      onFocusedContribution?.({
        targetNodeId,
        targetLabel: targetNode?.label || "",
        targetDescription: targetNode?.description || "",
        question: focused.question,
        answer: answerText,
        observations: data.observations,
        uncertainties: data.uncertainties,
        assumptions: data.assumptions,
        relationships: data.relationships,
        possibleFollowUpQuestions: data.possibleFollowUpQuestions,
        correlationId,
      });

      setProcessingStep("idle");

      // Deterministic presentation anchor: explicitly set the focused item to the
      // target node so the post-API success path always renders the correct state
      // regardless of render timing or concurrent parent updates.
      setFocusedPresentationItemId(targetNodeId);

      setFocusedInvestigations((prev) => ({
        ...prev,
        [targetNodeId]: { ...prev[targetNodeId], result: { ...data, correlationId }, answer: answerText, error: null },
      }));
    } catch (err) {
      setProcessingStep("idle");

      setFocusedPresentationItemId(targetNodeId);

      setFocusedInvestigations((prev) => ({
        ...prev,
        [targetNodeId]: { ...prev[targetNodeId], result: null, error: err.message || "Deconstruction failed" },
      }));
    }
  }

  async function submitFocusedAnswer() {
    if (!focused?.question?.trim() || !hasGraph) return;
    const targetNodeId = focusedPresentationItemId;
    await handleDeconstructSubmit(targetNodeId, focusedAnswer);
  }

  function retryFormulation() {
    const target = focusedPresentationItemId;
    if (!target) return;
    setFocusedInvestigations((prev) => ({
      ...prev,
      [target]: { ...prev[target], question: "", error: null },
    }));
    doFormulate(target);
  }

  function setFollowUpQuestion(followUpText) {
    const target = focusedPresentationItemId;
    if (!target || !followUpText?.trim()) return;

    // Deterministic presentation anchor: explicitly set after follow-up selection.
    setFocusedPresentationItemId(target);

    setFocusedInvestigations((prev) => ({
      ...prev,
      [target]: { ...prev[target], question: followUpText.trim(), answer: null },
    }));
    setFocusedAnswer("");
  }

  function hasFocusedContent() {
    if (!focused) return false;
    const q = focused.question;
    return Boolean(q?.trim()) || formulationStep === "active" || processingStep === "active" || focused.error;
  }

  // ── End RTO.13B ──────────────────────────────────────────────

  // ── Body scroll lock while overlay is open ────────────────
  useEffect(() => {
    if (isFocusedWorkspaceOpen) {
      document.body.style.overflow = "hidden";
      return () => { document.body.style.overflow = ""; };
    }
  }, [isFocusedWorkspaceOpen]);

  const canAnswer =
    status === "success" &&
    !isUpdating &&
    Boolean(result?.situationGraph) &&
    hasSelectedQuestion;

  const selectedQ = result?.selectedQuestion ?? null;

  // Determine whether the Current Understanding card should render:
  // — when there is a durable plain-language understanding, or
  // — when there is an actual summary from any graph snapshot, or
  // — when the investigation has reached a terminal state with no active question.
  const hasCurrentSummaryCondition =
    Boolean(propUnderstanding || graph?.currentSummary || result?.updatedSituationGraph?.currentSummary) || !hasSelectedQuestion;

  // ── RTO.29D — manage initial reflection lifecycle ────────────
  useEffect(() => {
    // Entry is now based on successful initial reconstruction state ONLY.
    // selectedQuestion is internal reasoning data — it must NOT gate the
    // post-Analyse presentation path.  Both null and populated
    // selectedQuestion enter Run A identically.
    const entering = status === "success" && hasGraph && propUnderstanding;
    if (entering) {
      setPostAnalyseStatus("success");
      setInitialReflectionActive(true);
    } else if (!entering && initialReflectionActive) {
      // Leave initial reflection when something changes (user interacts, status shifts)
      setInitialReflectionActive(false);
      setPostAnalyseStatus(null);
    }
  }, [status, result, hasGraph]);

  // Deactivate initial reflection when user submits a turn (leaves post-analyse).
  // DO NOT deactivate on formulationStep or processingStep transitions — those
  // are part of the focused workflow and must not break Run A's lifecycle.
  useEffect(() => {
    if (!initialReflectionActive) return;

    // If we've already transitioned out of post-analyse mode, bail early.
    // This prevents the effect from re-triggering on every state change after
    // an explicit deactivation and avoids spurious double-fires when multiple
    // dependencies change in the same commit.
    if (postAnalyseStatus !== "success") return;

    // Genuine exit: a turn has been submitted → history grows past zero.
    // No other lifecycle state (formulation, processing, focused IDs, etc.)
    // deactivates Run A during a focused investigation cycle.
    if (investigationHistory.length > 0) {
      setInitialReflectionActive(false);
      setPostAnalyseStatus(null);
    }
    // All other lifecycle events within the focused workflow are intentionally
    // ignored here — Run A stays active until an explicit turn is submitted.
  }, [initialReflectionActive, investigationHistory, postAnalyseStatus]);

  return (
    <div className="space-y-6" data-testid="reasoning-workspace">
      {/* ── Loading overlays ─────────────────────────────── */}
      {status === "loading" && (
        <LoadingOverlay
          isLoading={true}
          elapsed={startElapsed}
          currentMessage={startMsg}
          variant="initial"
        />
      )}

      {/* ── Provider unavailable recovery (always visible) ───────────── */}
      {isProviderUnavailable && (
        <ProviderUnavailableCard onRestart={onRestart} />
      )}

      {/* ── Malformed response recovery (always visible) ──────────────── */}
      {isMalformedResponse && (
        <MalformedResponseCard onRestart={onRestart} />
      )}

      {/* ── Unexpected state recovery ──────────────────── */}
      {(errorType === "unexpected-state") && result && (
        <UnexpectedStateCard
          stateName={result.stage || null}
          onRetry={updateStatus === "error" ? onRestart : null}
          onRestart={onRestart}
        />
      )}

      {/* ── No graph produced after initial analysis ───────── */}
      {(status === "success" || status === "error") && !graph ? (
        <div className="rounded-lg border border-yellow-300 bg-yellow-50 px-4 py-3 text-sm text-yellow-800">
          {diagnostics?.noQuestionReason
            ? "Validation failed — no structured graph output was produced."
            : "The analysis completed but did not produce a structured result."}
        </div>
      ) : (
        <>
          {/* ── RTO.29D — initial post-Analyse reflection ──────── */}
          {postAnalyseStatus === "success" && (
            <div className="space-y-6" data-testid="initial-reflection-surface">
              {/* Current Understanding + Situation — independent vertical flow */}
              <div className="flex gap-3 items-start flex-wrap">
                {/* Current Understanding — prominent orienting surface */}
                <div className={`rounded-xl border-[2.5px] border-teal-300/70 bg-gradient-to-b from-teal-50/60 to-white px-8 pt-7 pb-8 shadow-sm flex-1 min-w-0 ${hasGraph ? 'lg:max-w-2xl' : ''}`}>
                  <h2 className="mb-4 text-[11px] font-bold tracking-[.18em] uppercase text-teal-700/60">
                    Current Understanding
                  </h2>
                  <p className="text-lg leading-relaxed text-gray-800">{propUnderstanding}</p>
                </div>

                {/* Situation panel during initial reflection */}
                {hasGraph && (
                  <div className="space-y-6 lg:max-w-xs">
                    <OriginalSituation scenario={scenario} centralStatement={graph?.centralStatement} />
                  </div>
                )}
                {!hasGraph && scenario && (
                  <div className="space-y-6 lg:max-w-xs">
                    <div className="rounded-lg border border-gray-200/60 bg-gray-50/40 px-5 py-4">
                      <h2 className="mb-2 text-[11px] font-semibold tracking-widest uppercase text-gray-500">
                        Situation
                      </h2>
                      <p className="whitespace-pre-wrap text-sm leading-relaxed text-gray-600">
                        {scenario}
                      </p>
                    </div>
                  </div>
                )}
              </div>

              {/* Initial proposed findings — unknowns + plausible interpretations from reconstruction */}
              <div className="space-y-6" data-testid="initial-proposed-findings">
                {(() => {
                  const resolvedIds = new Set(graph?.resolvedNodeIds || []);

                  // Open Questions: unresolved unknown nodes only (investigable)
                  const openUnknowns = (graph?.nodes || []).filter(
                    (n) =>
                      n.kind === "unknown" &&
                      n.status !== "resolved" &&
                      !resolvedIds.has(n.id),
                  );

                  // Possible Interpretations: unresolved assumption nodes only (informational, not investigable)
                  const possibleInterpretations = (graph?.nodes || []).filter(
                    (n) =>
                      n.kind === "assumption" &&
                      n.status !== "resolved" &&
                      !resolvedIds.has(n.id),
                  );

                  return (
                    <>
                      {/* OPEN QUESTIONS — unknown nodes (clickable → focused investigation) */}
                      {openUnknowns.length > 0 && (
                        <div className="space-y-3">
                          <h2 className="text-[11px] font-semibold tracking-widest uppercase text-gray-500">
                            Open Questions
                          </h2>
                          {openUnknowns.map((node) => {
                            const isFocused = focusedPresentationItemId === node.id;
                            const hasCompleted = Boolean(
                              focusedInvestigations[node.id] &&
                              focusedInvestigations[node.id].question
                            );

                            function handleNodeClick(n) {
                              if (hasCompleted && selectedPresentationItemId === n.id) {
                                setFocusedPresentationItemId(n.id);
                                setIsFocusedWorkspaceOpen(true);
                                return;
                              }
                              startFocused(n.id);
                            }

                            return (
                              <button
                                key={node.id}
                                onClick={() => handleNodeClick(node)}
                                style={{ cursor: "pointer" }}
                                className="w-full text-left rounded-lg border border-gray-200 bg-white px-5 py-4 transition hover:border-gray-300 hover:bg-gray-50"
                              >
                                <span className={`block leading-snug ${isFocused ? "text-sm font-medium text-gray-900" : "text-sm text-gray-600"}`}>{node.label}</span>
                                {node.description && node.description !== node.label && (
                                  <p className="mt-1.5 text-xs leading-snug text-gray-500">{node.description}</p>
                                )}
                                {!isFocused && <span className="mt-2 block text-[10px] uppercase tracking-wider text-gray-400">Unclear</span>}
                              </button>
                            );
                          })}

                          {/* Focused content — rendered inline in the initial reflection surface (suppressed when overlay open) */}
                          {!isFocusedWorkspaceOpen && (() => {
                            const activeForFocus = openUnknowns.find((n) => focusedPresentationItemId === n.id);
                            if (!activeForFocus) return null;

                            const node = activeForFocus;
                            const hasCompleted = Boolean(
                              focusedInvestigations[node.id] &&
                              focusedInvestigations[node.id].question
                            );
                            const isFocused = focusedPresentationItemId === node.id;

                            return (
                              <FocusedQuestionBody
                                nodeId={node.id}
                                isFocused={isFocused}
                                hasCompletedInvestigation={() => hasCompleted}
                                focused={getFocusedInvestigation()}
                                formulationStep={formulationStep}
                                formulateMsg={formulateMsg}
                                processingStep={processingStep}
                                deconstructMsg={deconstructMsg}
                                focusedAnswer={focusedAnswer}
                                handleDeconstructSubmit={handleDeconstructSubmit}
                                retryFormulation={retryFormulation}
                                setFocusedAnswer={setFocusedAnswer}
                                setSelectedPresentationItemId={setSelectedPresentationItemId}
                                setFocusedPresentationItemId={setFocusedPresentationItemId}
                                setDoneForNowIds={setDoneForNowIds}
                                setFollowUpQuestion={setFollowUpQuestion}
                                focusedContributions={focusedContributions}
                                currentFindings={currentFindings || []}
                                onUpdateFindingDisposition={onUpdateFindingDisposition}
                                onUpdateFindingProposition={onUpdateFindingProposition}
                              />
                            );
                          })()}
                        </div>
                      )}

                      {/* POSSIBLE INTERPRETATIONS — assumption nodes (informational, not investigable) */}
                      {possibleInterpretations.length > 0 && (
                        <div className="space-y-3">
                          <h2 className="text-[11px] font-semibold tracking-widest uppercase text-gray-500">
                            Possible Interpretations
                          </h2>
                          {possibleInterpretations.map((node) => (
                            <div
                              key={node.id}
                              className="w-full text-left rounded-lg border border-blue-100 bg-blue-50/40 px-5 py-4"
                            >
                              <span className="block text-sm leading-relaxed text-gray-900">{node.label}</span>
                              {node.description && node.description !== node.label && (
                                <p className="mt-1.5 text-xs leading-snug text-gray-500">{node.description}</p>
                              )}
                              <span className="mt-2 block text-[10px] uppercase tracking-wider text-blue-400">Plausible interpretation</span>
                            </div>
                          ))}
                        </div>
                      )}
                    </>
                  );
                })()}
              </div>
      </div>
    )}


          {/* ── Workspace grid: persistent whenever a graph exists ─── */}
          {hasGraph && (
            <div className="grid grid-cols-1 gap-6 lg:grid-cols-3">

              {/* Current Understanding — independent row, full-width of left area (cols 1-2) */}
              {propUnderstanding && hasCurrentSummaryCondition && postAnalyseStatus !== "success" && (
                <div className="lg:row-start-1 lg:col-span-full rounded-xl border-[2.5px] border-teal-300/70 bg-gradient-to-b from-teal-50/60 to-white px-8 pt-7 pb-8 shadow-sm">
                  <CurrentUnderstandingCard currentSummary={graph?.currentSummary || result?.updatedSituationGraph?.currentSummary} plainLanguage={propUnderstanding} />
                </div>
              )}

              {/* Left column: Investigation + Open Questions (rows 2-3, columns 1-2) */}
              <div className="lg:row-start-2 lg:row-end-4 lg:col-start-1 lg:col-span-2 space-y-6">
                {postAnalyseStatus !== "success" && (
                  <CurrentInvestigationCard selectedQuestion={result?.selectedQuestion} graph={graph} />
                )}

                {postAnalyseStatus !== "success" && (
                  <OpenQuestionsPanel
                    graph={graph}
                    selectedPresentationItemId={selectedPresentationItemId}
                    focusedPresentationItemId={focusedPresentationItemId}
                    hasFocusedContent={hasFocusedContent}
                    focused={getFocusedInvestigation()}
                    formulationStep={formulationStep}
                    formulateMsg={formulateMsg}
                    processingStep={processingStep}
                    deconstructMsg={deconstructMsg}
                    doneForNowIds={doneForNowIds}
                    startFocused={startFocused}
                    handleDeconstructSubmit={handleDeconstructSubmit}
                    retryFormulation={retryFormulation}
                    setSelectedPresentationItemId={setSelectedPresentationItemId}
                    setFocusedPresentationItemId={setFocusedPresentationItemId}
                    setFocusedAnswer={setFocusedAnswer}
                    focusedAnswer={focusedAnswer}
                    setDoneForNowIds={setDoneForNowIds}
                    setFollowUpQuestion={setFollowUpQuestion}
                    focusedContributions={focusedContributions}
                    focusedInvestigations={focusedInvestigations}
                    setIsFocusedWorkspaceOpen={setIsFocusedWorkspaceOpen}
                    onUpdateFindingProposition={onUpdateFindingProposition}
                  />
                )}

                {/* Terminal state — suppressed during initial reflection */}
                {postAnalyseStatus !== "success" && status === "success" && !hasSelectedQuestion && showEvidenceLimit && (
                  <>
                    {genuineCompletion && (
                      <CompletionCard summary={resolveCurrentSummary(propUnderstanding || graph?.currentSummary || result?.updatedSituationGraph?.currentSummary)} />
                    )}
                    {!genuineCompletion ? (
                      <EvidenceLimitCard summary={resolveCurrentSummary(propUnderstanding || graph?.currentSummary || result?.updatedSituationGraph?.currentSummary)} />
                    ) : null}
                  </>
                )}

                {investigationHistory.length > 0 && (
                  <InvestigationHistory turns={investigationHistory} />
                )}

                {/* ── Experiment 12: progress panel A / B / C toggle (temporary experimental UI) — de-emphasised by branch-as-context experiment RTO.25D */}
                {hasGraph && (
                  <div className="hidden space-y-2">
                    <div className="flex items-center gap-2" role="radiogroup" aria-label="Progress panel variant">
                      <button
                        role="radio"
                        aria-checked={panelVariant === "a"}
                        onClick={() => setPanelVariant("a")}
                        onKeyDown={(e) => {
                          if (e.key === "ArrowRight") setPanelVariant("b");
                          if (e.key === "ArrowLeft") setPanelVariant("c");
                        }}
                        className={`text-xs transition ${panelVariant === "a" ? "font-medium text-gray-700 underline" : "text-gray-400 hover:text-gray-500"}`}
                      >
                        A
                      </button>
                      <span className="text-gray-300">/</span>
                      <button
                        role="radio"
                        aria-checked={panelVariant === "b"}
                        onClick={() => setPanelVariant("b")}
                        onKeyDown={(e) => {
                          if (e.key === "ArrowRight") setPanelVariant("c");
                          if (e.key === "ArrowLeft") setPanelVariant("a");
                        }}
                        className={`text-xs transition ${panelVariant === "b" ? "font-medium text-gray-700 underline" : "text-gray-400 hover:text-gray-500"}`}
                      >
                        B
                      </button>
                      <span className="text-gray-300">/</span>
                      <button
                        role="radio"
                        aria-checked={panelVariant === "c"}
                        onClick={() => setPanelVariant("c")}
                        onKeyDown={(e) => {
                          if (e.key === "ArrowRight") setPanelVariant("a");
                          if (e.key === "ArrowLeft") setPanelVariant("b");
                        }}
                        className={`text-xs transition ${panelVariant === "c" ? "font-medium text-gray-700 underline" : "text-gray-400 hover:text-gray-500"}`}
                      >
                        C (exp)
                      </button>
                    </div>
                    <div className="opacity-75">
                      {panelVariant === "a"
                        ? <InvestigationSummaryPanel graph={graph} selectedQuestion={selectedQ} result={result} updateStatus={updateStatus} />
                        : panelVariant === "b"
                          ? <InvestigationSummaryPanelV2 graph={graph} selectedQuestion={selectedQ} result={result} updateStatus={updateStatus} />
                          : <InvestigationSummaryPanelV3 graph={graph} selectedQuestion={selectedQ} result={result} />
                      }
                    </div>
                  </div>
                )}
              </div>

              {/* Right lane: stable supporting reference (independent column) */}
              {(scenario || graph?.centralStatement) && hasCurrentSummaryCondition && postAnalyseStatus !== "success" && (
                <div className="lg:row-start-2 lg:row-end-4 lg:col-start-3 space-y-6">
                  {/* Situation — always here when condition met, independent of left column height */}
                  <OriginalSituation scenario={scenario} centralStatement={graph?.centralStatement || scenario} />
                  {/* RTO.25B — temporarily hidden to reduce competing navigation while branch-experiment is active */}
                  <div className="hidden">
                    <InvestigationMap turnCount={investigationHistory.length} />
                  </div>
                </div>
              )}

              {/* Possible Interpretations — persistent provisional hypothesis cards (spans full workspace width, below Investigation) */}
              {(() => {
                const resolvedIds = new Set(graph?.resolvedNodeIds || []);
                const interpretationNodes = (graph?.nodes || []).filter(
                  (n) =>
                    n.kind === "assumption" &&
                    n.status !== "resolved" &&
                    !resolvedIds.has(n.id),
                );

                return postAnalyseStatus !== "success" && interpretationNodes.length > 0 ? (
                  <div className="lg:row-start-4 lg:col-span-full space-y-3">
                    <h2 className="text-[11px] font-semibold tracking-widest uppercase text-gray-500">
                      Possible Interpretations
                    </h2>
                    {interpretationNodes.map((node) => (
                      <div
                        key={node.id}
                        className="w-full text-left rounded-lg border border-blue-100 bg-blue-50/40 px-5 py-4"
                      >
                        <span className="block text-sm leading-relaxed text-gray-900">{node.label}</span>
                        {node.description && node.description !== node.label && (
                          <p className="mt-1.5 text-xs leading-snug text-gray-500">{node.description}</p>
                        )}
                        <span className="mt-2 block text-[10px] uppercase tracking-wider text-blue-400">Plausible interpretation</span>
                      </div>
                    ))}
                  </div>
                ) : null;
              })()}
            </div>
          )}

          {/* ── Focused investigation overlay workspace ─────────── */}
          {isFocusedWorkspaceOpen && (
            <div
              className="!mt-0 fixed inset-0 z-50 flex items-center justify-center"
              onClick={(e) => { if (e.target === e.currentTarget) setIsFocusedWorkspaceOpen(false); }}
            >
              {/* Dimmed background — prevents interaction with page behind overlay */}
              <div className="absolute inset-0 bg-gray-900/40 backdrop-blur-[1px]" />

              {/* Workspace container: constrained to viewport height, not pushed by content */}
              <div
                className="relative z-10 my-6 flex w-[94vw] max-h-[calc(100vh-3rem)] max-w-[1600px] flex-col overflow-hidden rounded-xl border border-gray-200/60 bg-white shadow-xl sm:w-[90vw] md:w-[88vw]"
                onClick={(e) => e.stopPropagation()}
                role="dialog"
                aria-label="Focused investigation workspace"
              >
                {/* Floating close control — persistent, top-right inside panel */}
                <button
                  onClick={(e) => { e.stopPropagation(); setFocusedAnswer(""); setFocusedPresentationItemId(null); setIsFocusedWorkspaceOpen(false); }}
                  style={{ cursor: "pointer" }}
                  aria-label="Close investigation"
                  title="Close investigation"
                  className="absolute right-4 top-3 z-20 flex items-center gap-2 rounded-lg border border-gray-300 bg-white/90 px-4 py-2 text-sm font-medium text-gray-600 shadow-sm transition hover:bg-gray-50"
                >
                  <svg width="14" height="14" viewBox="0 0 14 14" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round"><path d="M1 1l12 12M13 1L1 13"/></svg>
                  Close investigation
                </button>

                {/* Scrollable workspace body */}
                <div className="flex-1 overflow-y-auto px-4 pb-8 pt-[64px]">
                  {hasFocusedContent() || formulationStep === "active" ? (
                    <>
                      <FocusedInvestigationWorkspace
                        nodeId={focusedPresentationItemId}
                        focused={getFocusedInvestigation()}
                        formulationStep={formulationStep}
                        formulateMsg={formulateMsg}
                        processingStep={processingStep}
                        deconstructMsg={deconstructMsg}
                        focusedAnswer={focusedAnswer}
                        handleDeconstructSubmit={handleDeconstructSubmit}
                        retryFormulation={retryFormulation}
                        setFocusedAnswer={setFocusedAnswer}
                        setSelectedPresentationItemId={setSelectedPresentationItemId}
                        setFocusedPresentationItemId={setFocusedPresentationItemId}
                        setDoneForNowIds={setDoneForNowIds}
                        setFollowUpQuestion={setFollowUpQuestion}
                        setIsFocusedWorkspaceOpen={setIsFocusedWorkspaceOpen}
                        hasCompletedInvestigation={() => {
                          if (!focused) return false;
                          const q = focused.question;
                          return Boolean(q?.trim());
                        }}
                        focusedContributions={focusedContributions}
                        currentFindings={currentFindings || []}
                        onUpdateFindingDisposition={onUpdateFindingDisposition}
                        onUpdateFindingProposition={onUpdateFindingProposition}
                      />
                      {/* Workspace navigation — hidden during formulation/loading states */}
                      {formulationStep !== "active" && (
                        <FocusedWorkspaceNavigation
                          nodeId={focusedPresentationItemId}
                          doneForNow={() => {
                            setDoneForNowIds((prev) => [...prev, focusedPresentationItemId]);
                            setFocusedAnswer("");
                            setFocusedPresentationItemId(null);
                          }}
                          isDoneForNowActive={Boolean(getFocusedInvestigation()?.question?.trim())}
                          onBackToOpenQuestions={() => {
                            setFocusedAnswer("");
                            setFocusedPresentationItemId(null);
                          }}
                        />
                      )}
                    </>
                  ) : (
                    <div className="w-full max-w-[1400px] mx-auto">
                      <div className="rounded-lg border border-gray-200 bg-white p-8 text-center">
                        <p className="text-base font-medium text-gray-500">Formulating your question…</p>
                        <p className="mt-3 text-sm text-gray-400">{formulateMsg}</p>
                      </div>
                    </div>
                  )}
                </div>
              </div>
            </div>
          )}

          {/* Developer details — full-width beneath workspace */}
          {(status === "success" || status === "error") && graph && (
            <DeveloperDetails
              graph={graph}
              selectedQuestion={selectedQ}
              diagnostics={diagnostics}
              newlySurfacedNodeIds={newlySurfacedNodeIds}
              updateResult={updateStatus === "success" ? result : null}
            />
          )}
        </>
      )}

      {/* ── Errors (always visible above debug) ─────────── */}
      {(status === "error" || updateStatus === "error") && (
        <div className="space-y-3">
          {status === "error" && result?.error && (
            <div className="rounded-lg border border-red-300 bg-red-50 px-4 py-3 text-sm text-red-700 whitespace-pre-wrap">
              Error: {result.error}
            </div>
          )}
          {updateStatus === "error" && !isProviderUnavailable && !isMalformedResponse && result?.updateError && (
            <div className="rounded-lg border border-red-300 bg-red-50 px-4 py-3 text-sm text-red-700">
              Update error: {result.updateError.error || JSON.stringify(result.updateError)}
            </div>
          )}
        </div>
      )}
    </div>
  );
}

export { useLoadingStatus, INITIAL_MESSAGES, UPDATE_MESSAGES, LoadingOverlay, resolveCurrentSummary, isTechnicalSummary, ContinueLaterBanner };