src/lib/agent/GraphOrchestrator.ts

/**
 * GraphOrchestrator.ts — Executes a TaskGraph (FASE 4.1)
 *
 * Pipeline:
 *   TaskGraph → [ready nodes] → execute in parallel → mark done →
 *   → next layer → ... → synthesize → updateMemory
 *
 * The orchestrator calls the same `executeTool` function used by
 * the ReAct loop — no duplication, no regressions.
 *
 * Designed for iPhone: low memory footprint, no blocking operations,
 * concurrency capped at 2 parallel tool calls.
 *
 * ── Resilience additions (S760) ───────────────────────────────────────────────
 *
 * S760-A │ Abort cleanup ("Dangling Nodes")
 *         │ Quando AbortSignal scatta, tutti i nodi in stato "running"
 *         │ vengono marcati "failed" con msg "abortito" e i loro dipendenti
 *         │ propagati come "skipped". Lo stato finale è sempre coerente.
 *
 * S760-B │ Memory offload su IndexedDB ("Memory Pressure" iOS)
 *         │ Risultati tool > OFFLOAD_THRESHOLD_BYTES (4 KB) vengono scritti
 *         │ su vfsDb.graphToolResults. In memoria resta solo un ref
 *         │ "@@dexie:{nodeId}". La synthesis legge da Dexie al momento
 *         │ della(). Fallsafe: se Dexie fallisce, usa memoria.
 *
 * S760-C │ Adaptive replanning su nodo critico fallito ("Silent Dep Failures")
 *         │ Se un nodo con priority < CRITICAL_PRIORITY fallisce, invoca
 *         │ adaptiveReplan() che costruisce un piano alternativo e lo
 *         │ injetta nel grafo corrente senza ripartire da zero.
 *
 * S760-D │ Checkpointing + resume ("State Serialization")
 *         │ Dopo ogni markNode, il grafo viene serializzato su
 *         │ vfsDb.taskGraphs. All'avvio, loadIncompleteGraph() ritorna
 *         │ il grafo parziale (se esistente) permettendo il resume.
 *         │ Cleanup automatico dopo completamento.
 *
 * Invarianti rispettate:
 *   - S330: nessun setInterval (i checkpoint usano await Dexie sincrona)
 *   - S639: slot _running rilasciato durante backoff — non modified
 *   - S646: retryPolicy dal contratto del tool — non modified
 *   - S643: verifier wrapped in try/catch — non modified
 *   - S637: chiavi composite per tool duplicati — non modified
 *   - Safari-safe: nessun SharedArrayBuffer, AbortSignal.any() sostituito
 *                  da listener manuale (già presente)
 */

import {
  type TaskGraph,
  type TaskNode,
  buildGraph,
  getReadyNodes,
  markNode,
  graphDone,
} from "./TaskGraph";
import { verifyToolResult, annotateWithProof } from "./verifier";
import { updateMemoryFromGraph, sessionMemory } from "./MemoryUpdater";
import { safeValidateInput, getToolTimeout, TOOL_CONTRACTS } from ".";

// ─── vfsDb import (lazy per evitare circular deps a load time) ────────────────
// Nota: db è VFSDatabase | null — usa db?.table invece di (db as any).table
// Importato in modo lazy nelle funzioni che lo usano (checkpoint + offload)
// così se IndexedDB non è disponibile (test unitari, SSR) il resto funziona.
let _vfsDb: typeof import("../vfsDb").vfsDb | null = null;
async function _getVfsDb() {
  if (!_vfsDb) {
    try {
      const mod = await import("../vfsDb");
      _vfsDb = mod.vfsDb;
    } catch {
      _vfsDb = null;
    }
  }
  return _vfsDb;
}

export type ToolExecutor = (name: string, args: Record<string, unknown>) => Promise<string>;

export interface OrchestratorCallbacks {
  onNodeStart?:    (node: TaskNode) => void;
  onNodeDone?:     (node: TaskNode) => void;
  onNodeFailed?:   (node: TaskNode) => void;
  onStatus?:       (msg: string) => void;
  onProgress?:     (done: number, total: number) => void;
}

export interface OrchestrationResult {
  success:       boolean;
  output:        string;      // aggregated results for synthesizer
  toolResults:   Map<string, string>;
  failedNodes:   string[];
  skippedNodes:  string[];    // S637: nodi saltati per dipendenza fallita upstream
  memoryUpdated: boolean;
}

// ─── S760-B: Memory offload constants ────────────────────────────────────────
// Risultati > 4 KB vengono offloadati su Dexie invece di restare in RAM.
// Su iPhone con 3-4 GB RAM condivisa tra app e browser, ogni Map entry
// da 10+ KB è un potenziale contributor al tab kill di Safari.
const OFFLOAD_THRESHOLD_BYTES = 4_096;  // 4 KB
const OFFLOAD_REF_PREFIX      = "@@dexie:"; // sentinella in toolResults Map

// ─── S760-C: Adaptive replanning threshold ────────────────────────────────────
// Nodi con priority < soglia sono "critici" — il fallimento attiva il replanning.
// La priority viene da executionPlanner (S421). 0 = primissimo nel piano.
// Soglia 3 = i 3 passi più importanti del piano (auth, db, api-router)
// sono critici; quelli secondari (UI, styling, test) non triggerano replan.
const CRITICAL_PRIORITY = 3;

// Fix 1 (S381): concorrenza dinamica basata sul tipo di tool
const LIGHT_TOOLS = new Set([
  "get_weather", "get_news", "get_currency", "get_stock",
  "search_wikipedia", "math_eval", "get_datetime",
  "search_github", "generate_image", "get_ip_info", "get_joke",
]);
const HEAVY_TOOLS = new Set([
  "run_code", "execute_shell", "pip_install",
  "read_pdf", "create_webpage", "write_file", "iterate_file",
]);

function maxConcurrentFor(nodes: TaskNode[]): number {
  const tools = nodes.map(n => n.tool ?? "");
  if (tools.every(t => LIGHT_TOOLS.has(t))) return 4;
  if (tools.some(t => HEAVY_TOOLS.has(t)))  return 1;
  return 2;
}

const TICK_MS = 50;

function isTransientError(msg: string): boolean {
  const m = msg.toLowerCase();
  return (
    m.includes("fetch failed")        ||
    m.includes("network error")       ||
    m.includes("networkerror")        ||
    m.includes("failed to fetch")     ||
    m.includes("econnrefused")        ||
    m.includes("enotfound")           ||
    m.includes("socket hang up")      ||
    m.includes("timeout")             ||
    m.includes("429")                 ||
    m.includes("rate limit")          ||
    m.includes("too many requests")   ||
    m.includes("503")                 ||
    m.includes("502")                 ||
    m.includes("504")                 ||
    m.includes("service unavailable") ||
    m.includes("bad gateway")         ||
    m.includes("gateway timeout")
  );
}

// ─── S760-A: Abort cleanup ────────────────────────────────────────────────────
/**
 * Marca come "failed" tutti i nodi ancora in stato "running" dopo un abort.
 * La propagazione degli skipped viene gestita da markNode() già esistente.
 * Deve essere chiamata nel finally del loop principale, SEMPRE.
 */
function _cleanupDanglingNodes(graph: TaskGraph, reason: string): void {
  for (const node of graph.nodes.values()) {
    if (node.status === "running") {
      // markNode propaga automaticamente "skipped" ai dipendenti
      markNode(graph, node.id, "failed", undefined, `abortito: ${reason}`);
    }
  }
}

// ─── S760-B: Tool result offloading ──────────────────────────────────────────

/**
 * Scrive il risultato di un tool su Dexie se supera la soglia.
 * Ritorna la stringa da usare in toolResults: o il result originale (piccolo)
 * o un ref "@@dexie:{nodeId}" (grande, offloadato).
 * Fire-and-forget safe: se Dexie fallisce, usa memoria senza crash.
 */
async function _maybeOffloadResult(nodeId: string, result: string): Promise<string> {
  // Usa byteLength (UTF-8) se disponibile, altrimenti lunghezza caratteri
  const byteSize = (typeof TextEncoder !== "undefined")
    ? new TextEncoder().encode(result).length
    : result.length;

  if (byteSize <= OFFLOAD_THRESHOLD_BYTES) return result;

  try {
    const db = await _getVfsDb();
    if (!db) return result; // Dexie non disponibile → usa memoria
    // eslint-disable-next-line @typescript-eslint/no-explicit-any
    await db?.graphToolResults?.put({ id: nodeId, result, savedAt: Date.now() });
    return `${OFFLOAD_REF_PREFIX}${nodeId}`;
  } catch {
    // Dexie piena o errore → fallback: tronca il risultato in memoria
    return result.slice(0, OFFLOAD_THRESHOLD_BYTES) + " [troncato per memoria]";
  }
}

/**
 * Risolve un ref "@@dexie:{nodeId}" in Dexie, o ritorna la stringa diretta.
 * Usata da collectResultsResolved() nella fase di synthesis.
 */
async function _resolveOffloadedResult(refOrResult: string): Promise<string> {
  if (!refOrResult.startsWith(OFFLOAD_REF_PREFIX)) return refOrResult;
  const nodeId = refOrResult.slice(OFFLOAD_REF_PREFIX.length);
  try {
    const db = await _getVfsDb();
    if (!db) return "[risultato non disponibile]";
    // eslint-disable-next-line @typescript-eslint/no-explicit-any
    const entry = await db?.graphToolResults?.get(nodeId);
    return entry?.result ?? "[risultato scaduto da Dexie]";
  } catch {
    return "[errore lettura Dexie]";
  }
}

/**
 * Versione async di che risolve i ref Dexie prima di aggregare.
 * Sostituisce(graph) nella fase di synthesis quando l'offload è attivo.
 */
async function collectResultsResolved(graph: TaskGraph): Promise<string> {
  const results: string[] = [];
  for (const node of graph.nodes.values()) {
    if (node.type === "tool_call" && node.result) {
      const resolved = await _resolveOffloadedResult(node.result);
      results.push(`[${node.label}]\n${resolved}`);
    }
  }
  return results.join("\n\n---\n\n");
}

// ─── S760-C: Adaptive replanning ─────────────────────────────────────────────

/**
 * Tenta di costruire un piano alternativo per un nodo critico fallito.
 * Non usa LLM esterno per non aggiungere latency — usa una strategia
 * deterministica: costruisce un singolo nodo di "recupero" che usa
 * un tool alternativo per raggiungere lo stesso obiettivo parziale.
 *
 * Logica:
 *   - tool fallito è di tipo "fetch" → prova tool alternativo nello stesso gruppo
 *   - tool fallito è "write_file" → prova "apply_patch" sullo stesso path
 *   - altrimenti → aggiunge un nodo "run_code" con il label del nodo fallito
 *
 * Il nodo alternativo è inserito nel grafo DOPO tutti i nodi done,
 * con deps che puntano all'ultimo nodo done (non quello fallito).
 * I nodi che dipendevano dal fallito vengono re-wired al nuovo nodo.
 */
function _adaptiveReplan(graph: TaskGraph, failedNodeId: string): boolean {
  const failedNode = graph.nodes.get(failedNodeId);
  if (!failedNode?.tool) return false;

  // Mappa di fallback per tool type
  const FETCH_FALLBACKS: Record<string, string> = {
    web_search:       "web_research",
    web_research:     "get_news",
    read_page:        "fetch_url",
    fetch_url:        "web_search",
    search_wikipedia: "web_search",
    search_github:    "web_search",
  };
  const WRITE_FALLBACKS: Record<string, string> = {
    write_file:   "iterate_file",
    iterate_file: "write_file",
    apply_patch:  "write_file",
    run_code:     "execute_shell",
    execute_shell:"run_code",
  };

  const fallbackTool =
    FETCH_FALLBACKS[failedNode.tool] ??
    WRITE_FALLBACKS[failedNode.tool] ??
    null;

  if (!fallbackTool) return false;

  // Trova l'ultimo nodo "done" come nuovo anchor delle dipendenze
  const lastDoneId = [...graph.nodes.values()]
    .filter(n => n.status === "done")
    .sort((a, b) => (b.finishedAt ?? 0) - (a.finishedAt ?? 0))[0]?.id;

  if (!lastDoneId) return false;

  // Crea nodo alternativo
  const altId = `replan-${failedNodeId}-${Date.now()}`;
  const altNode: TaskNode = {
    id:        altId,
    type:      "tool_call",
    label:     `[Replan] ${failedNode.label} via ${fallbackTool}`,
    tool:      fallbackTool,
    input:     { ...(failedNode.input ?? {}), _replan: true },
    deps:      [lastDoneId],
    status:    "pending",
    priority:  (failedNode.priority ?? 999) + 0.5, // subito dopo il fallito
  };
  graph.nodes.set(altId, altNode);
  graph.edges.push({ from: lastDoneId, to: altId });

  // Re-wire: i nodi che dipendevano dal fallito ora dipendono dall'alternativo
  for (const node of graph.nodes.values()) {
    if (node.status === "skipped" && node.deps.includes(failedNodeId)) {
      // Riporta "pending" e sostituisce la dipendenza
      node.status = "pending";
      node.error  = undefined;
      node.deps   = node.deps.map(d => d === failedNodeId ? altId : d);
      graph.edges.push({ from: altId, to: node.id });
    }
  }

  return true; // replan riuscito
}

// ─── S760-D: Graph checkpointing ─────────────────────────────────────────────

/**
 * Serializza il grafo su Dexie.taskGraphs.
 * Fire-and-forget: mai lancia eccezioni, mai blocca il loop.
 * Serializza solo campi primitivi — `nodes` è una Map, va convertita.
 */
async function _checkpointGraph(graph: TaskGraph): Promise<void> {
  try {
    const db = await _getVfsDb();
    if (!db) return;

    const serialized = JSON.stringify({
      id:        graph.id,
      goal:      graph.goal,
      createdAt: graph.createdAt,
      nodes:     [...graph.nodes.entries()].map(([id, node]) => { const { id: _nid, ...rest } = node as unknown as Record<string,unknown>; return { id, ...rest }; }),
      edges:     graph.edges,
    });

    // eslint-disable-next-line @typescript-eslint/no-explicit-any
    await db?.taskGraphs?.put({
      id:         graph.id,
      graphState: serialized,
      goal:       graph.goal.slice(0, 200),
      timestamp:  Date.now(),
      status:     "incomplete",
    });
  } catch {
    // Dexie piena o schema non ancora aggiornato → silenzio
  }
}

/**
 * Marca il grafo come completato su Dexie (cleanup automatico post-run).
 * In alternativa potrebbe eliminarlo — lo marchiamo "complete" per
 * permettere analisi post-hoc senza occupare spazio indefinitamente.
 * TTL: gestito da pruneCompletedGraphs() che può essere chiamata on-demand.
 */
async function _markGraphComplete(graphId: string): Promise<void> {
  try {
    const db = await _getVfsDb();
    if (!db) return;
    // eslint-disable-next-line @typescript-eslint/no-explicit-any
    await db?.taskGraphs?.update(graphId, { status: "complete", completedAt: Date.now() });
  } catch { /* non-blocking */ }
}

/**
 * Deserializza un grafo da una stringa JSON (salvata da _checkpointGraph).
 * Ricostruisce la Map<string, TaskNode> dal formato array serializzato.
 */
function _deserializeGraph(graphState: string): TaskGraph | null {
  try {
    const raw = JSON.parse(graphState) as {
      id: string;
      goal: string;
      createdAt: number;
      nodes: Array<TaskNode & { id: string }>;
      edges: Array<{ from: string; to: string }>;
    };
    return {
      id:        raw.id,
      goal:      raw.goal,
      createdAt: raw.createdAt,
      nodes:     new Map(raw.nodes.map(n => [n.id, n])),
      edges:     raw.edges,
    };
  } catch {
    return null;
  }
}

// ─── Public API: load incomplete graph on startup ─────────────────────────────

export interface IncompleteGraphInfo {
  graphId:   string;
  goal:      string;
  timestamp: number;
}

/**
 * Ritorna la lista di grafi incompleti salvati su Dexie.
 * Chiamato da main.tsx all'avvio per offrire all'utente il resume.
 * Non lancia mai eccezioni.
 */
export async function listIncompleteGraphs(): Promise<IncompleteGraphInfo[]> {
  try {
    const db = await _getVfsDb();
    if (!db) return [];
    // eslint-disable-next-line @typescript-eslint/no-explicit-any
    const rows = await db?.taskGraphs
      ?.where("status")
      .equals("incomplete")
      .sortBy("timestamp") ?? [];
    return rows.map((r: { id: string; goal: string; timestamp: number }) => ({
      graphId:   r.id,
      goal:      r.goal,
      timestamp: r.timestamp,
    }));
  } catch {
    return [];
  }
}

/**
 * Carica e deserializza un grafo incompleto da Dexie dato il suo ID.
 * Usato da GraphOrchestrator.run() in modalità resume.
 */
export async function loadIncompleteGraph(graphId: string): Promise<TaskGraph | null> {
  try {
    const db = await _getVfsDb();
    if (!db) return null;
    // eslint-disable-next-line @typescript-eslint/no-explicit-any
    const row = await db?.taskGraphs?.get(graphId);
    if (!row?.graphState) return null;
    return _deserializeGraph(row.graphState);
  } catch {
    return null;
  }
}

/**
 * Elimina i grafi completati più vecchi di TTL_MS.
 * Chiamabile periodicamente o manualmente dall'utente.
 */
export async function pruneCompletedGraphs(ttlMs = 7 * 24 * 60 * 60_000): Promise<void> {
  try {
    const db = await _getVfsDb();
    if (!db) return;
    const cutoff = Date.now() - ttlMs;
    // eslint-disable-next-line @typescript-eslint/no-explicit-any
    await db?.taskGraphs
      ?.where("status")
      .equals("complete")
      .filter((r: { completedAt?: number }) => (r.completedAt ?? 0) < cutoff)
      .delete();
  } catch { /* non-blocking */ }
}


// ─── S760-D: ignoreGraph + resume singleton ──────────────────────────────────

/**
 * Ignora definitivamente un grafo incompleto rimuovendolo da Dexie.
 * Chiamato da ResumeGraphBanner quando l'utente clicca "Ignora".
 * Fire-and-forget: mai lancia eccezioni.
 */
export async function ignoreGraph(graphId: string): Promise<void> {
  try {
    const db = await _getVfsDb();
    if (!db) return;
    // eslint-disable-next-line @typescript-eslint/no-explicit-any
    await db?.taskGraphs?.delete(graphId);
  } catch { /* non-blocking */ }
}

/**
 * Modulo-level ref per il grafo parziale da riprendere.
 * Impostato da ResumeGraphBanner via App.tsx onResume.
 * Consumato (e azzerato) da graphOrchestrationBlock prima di planToGraph.
 */
let _pendingResumeGraph: TaskGraph | null = null;

/** Imposta il grafo parziale da riprendere al prossimo run(). */
export function setPendingResumeGraph(graph: TaskGraph): void {
  _pendingResumeGraph = graph;
}

/** Preleva (e azzera) il grafo in attesa di resume. Usato da graphOrchestrationBlock. */
export function takePendingResumeGraph(): TaskGraph | null {
  const g = _pendingResumeGraph;
  _pendingResumeGraph = null;
  return g;
}


// ─── Node executors ───────────────────────────────────────────────────────────

// Gap-1.2 fix (S723 + S724-EXT): enrich dependent node input with upstream results.
function enrichNodeInput(node: TaskNode, graph: TaskGraph): void {
  if ((node as unknown as Record<string, unknown>)._enriched) return;
  if (!node.deps?.length) return;
  const ups = node.deps
    .map(id => graph.nodes.get(id))
    .filter((d): d is TaskNode => !!d && d.status === "done" && !!d.result)
    // S760-B: un ref "@@dexie:" è un risultato grande — usiamo un placeholder
    // invece di fetch asincrona (enrichNodeInput è sincrona per design)
    .map(d => d.result!.startsWith(OFFLOAD_REF_PREFIX)
      ? "[risultato grande — vedi tool precedente]"
      : d.result!);
  if (!ups.length) return;
  (node as unknown as Record<string, unknown>)._enriched = true;
  const combined = ups.join("\n---\n").slice(0, 800);
  const allText  = ups.join(" ");
  if (!node.input) return;
  if ("query"   in node.input) { node.input = { ...node.input, context: combined }; }
  else if ("url" in node.input) {
    const m = allText.match(/https?:\/\/[^\s"'<>]+/);
    if (m) node.input = { ...node.input, url: m[0] };
  } else if ("code"    in node.input) {
    const existing = String(node.input.code ?? "").trim();
    const upSlice  = combined.slice(0, 400).replace(/`{3}/g, "'''");
    node.input = { ...node.input, code: `# --- upstream context ---\n# ${upSlice.replace(/\n/g, "\n# ")}\n# --- end context ---\n\n${existing}` };
  } else if ("content" in node.input) {
    const existing = String(node.input.content ?? "").trim();
    const upSlice  = combined.slice(0, 400);
    node.input = { ...node.input, content: existing ? `${existing}\n\n# Dati upstream:\n# ${upSlice.replace(/\n/g, "\n# ")}` : upSlice };
  } else if ("html"    in node.input) {
    const safe = combined.slice(0, 300).replace(/-->/g, "-- >");
    node.input = { ...node.input, html: `<!-- upstream: ${safe} -->\n${String(node.input.html ?? "")}` };
  } else if ("input"   in node.input) {
    node.input = { ...node.input, input: `${String(node.input.input ?? "")}\n\nContesto upstream:\n${combined.slice(0, 400)}` };
  }
}

async function executeToolNode(
  node: TaskNode,
  executor: ToolExecutor,
  signal: AbortSignal,
): Promise<string> {
  if (!node.tool) throw new Error(`Nodo tool_call senza tool: ${node.id}`);

  const timeout       = getToolTimeout(node.tool);
  const validatedInput = safeValidateInput(node.tool, node.input ?? {});

  const ctrl = new AbortController();
  const timer = setTimeout(() => ctrl.abort(), timeout);
  const onParentAbort = () => ctrl.abort();
  signal.addEventListener("abort", onParentAbort, { once: true });

  try {
    const result = await executor(node.tool, validatedInput);
    clearTimeout(timer);
    let annotated: string;
    try {
      const vr = verifyToolResult(node.tool, validatedInput, result);
      annotated = annotateWithProof(node.tool, result, vr);
    } catch {
      annotated = result;
    }
    return annotated;
  } finally {
    clearTimeout(timer);
    signal.removeEventListener("abort", onParentAbort);
  }
}

async function executeVerifyNode(node: TaskNode, graph: TaskGraph): Promise<string> {
  const toolNodeId = node.deps[0];
  const toolNode   = graph.nodes.get(toolNodeId);
  if (!toolNode?.result) return "⚠️ Nessun risultato da verificare";

  // S760-B: resolve ref Dexie se necessario
  const realResult = toolNode.result.startsWith(OFFLOAD_REF_PREFIX)
    ? await _resolveOffloadedResult(toolNode.result)
    : toolNode.result;

  const vr = verifyToolResult(
    node.tool ?? toolNode.tool ?? "",
    toolNode.input ?? {},
    realResult,
  );
  return vr.verified
    ? `✅ Verificato: ${vr.proof}`
    : `⚠️ Non verificato: ${vr.warning ?? vr.proof}`;
}

async function executeMemoryNode(_node: TaskNode, graph: TaskGraph): Promise<string> {
  const result = await updateMemoryFromGraph(graph);
  return `✅ Memoria aggiornata: ${result.saved} fatti salvati`;
}

// ─── Main orchestrator ────────────────────────────────────────────────────────

export class GraphOrchestrator {

  async run(
    graph: TaskGraph,
    executor: ToolExecutor,
    callbacks: OrchestratorCallbacks = {},
    signal?: AbortSignal,
  ): Promise<OrchestrationResult> {
    let _running = 0;
    const toolResults    = new Map<string, string>();
    const failedNodes:  string[] = [];
    let memoryUpdated = false;

    callbacks.onStatus?.(`Avvio grafo: ${graph.goal.slice(0, 60)}…`);

    // S760-D: checkpoint iniziale — registra il grafo come "incomplete" subito
    // così se la tab viene killata prima del primo nodo completato, il grafo
    // è già in Dexie e potrà essere ripreso.
    await _checkpointGraph(graph).catch(() => {});

    try {
      while (!graphDone(graph) && !(signal?.aborted)) {
        const ready = getReadyNodes(graph).sort(
          (a, b) => (a.priority ?? 999) - (b.priority ?? 999)
        );

        if (ready.length === 0) break;

        const batch = ready.slice(0, maxConcurrentFor(ready) - _running);
        if (batch.length === 0) {
          await new Promise(r => setTimeout(r, TICK_MS));
          continue;
        }

        const promises = batch.map(async (node) => {
          markNode(graph, node.id, "running");
          callbacks.onNodeStart?.(node);
          _running++;

          try {
            let result = "";

            switch (node.type) {
              case "plan":
                result = graph.goal;
                break;

              case "tool_call": {
                const _contract       = TOOL_CONTRACTS[node.tool as keyof typeof TOOL_CONTRACTS];
                const _contractMax    = (_contract?.retryPolicy?.maxAttempts ?? 3) - 1;
                const _MAX_RETRIES    = Math.min(_contractMax, 2);
                const _BACKOFF_MS     = [300, 900] as const;
                enrichNodeInput(node, graph);
                let _lastErr: Error | undefined;

                for (let _attempt = 0; _attempt <= _MAX_RETRIES; _attempt++) {
                  if (_attempt > 0) {
                    _running--;
                    try {
                      await new Promise(r => setTimeout(r, _BACKOFF_MS[_attempt - 1]));
                    } finally {
                      _running++;
                    }
                    if (signal?.aborted) break;
                  }
                  try {
                    result = await executeToolNode(node, executor, signal ?? new AbortController().signal);
                    _lastErr = undefined;
                    break;
                  } catch (err) {
                    _lastErr = err instanceof Error ? err : new Error(String(err));
                    if (!isTransientError(_lastErr.message) || signal?.aborted) break;
                  }
                }
                if (_lastErr) throw _lastErr;
                break;
              }

              case "verify":
                result = await executeVerifyNode(node, graph);
                break;

              case "memory":
                result = await executeMemoryNode(node, graph);
                memoryUpdated = true;
                break;

              case "synthesize":
                // S760-B: collectResultsResolved risolve i ref Dexie
                result = await collectResultsResolved(graph);
                break;

              default:
                result = "";
            }

            // S647: hollow success guard
            if (node.type === "tool_call" && (!result || !result.trim())) {
              result = `⚠️ [${node.tool}] nessun output prodotto`;
            }

            // S760-B: offload su Dexie se risultato grande
            let storedResult = result;
            if (node.type === "tool_call" && result && !result.startsWith("⚠️")) {
              storedResult = await _maybeOffloadResult(node.id, result);
            }

            markNode(graph, node.id, "done", storedResult);

            if (node.type === "tool_call" && node.tool) {
              const _prevCount = [...toolResults.keys()]
                .filter(k => k === node.tool || k.startsWith(node.tool + ":")).length;
              const _toolKey = _prevCount === 0
                ? node.tool!
                : `${node.tool}:${_prevCount + 1}`;
              toolResults.set(_toolKey, storedResult);
              sessionMemory.add("tool", _toolKey, result.slice(0, 400)); // S609: 200→400
            }

            callbacks.onNodeDone?.(node);

          } catch (err) {
            const msg = err instanceof Error ? err.message : String(err);
            markNode(graph, node.id, "failed", undefined, msg);
            failedNodes.push(node.id);
            callbacks.onNodeFailed?.(node);

            // S760-C: adaptive replanning su nodo critico
            if (
              node.type === "tool_call" &&
              (node.priority ?? 999) < CRITICAL_PRIORITY &&
              !signal?.aborted
            ) {
              const replanned = _adaptiveReplan(graph, node.id);
              if (replanned) {
                callbacks.onStatus?.(`↩ Nodo critico fallito — piano alternativo attivato`);
                // Rimuovi il nodo dalla lista failedNodes poiché è stato recuperato
                const fi = failedNodes.indexOf(node.id);
                if (fi !== -1) failedNodes.splice(fi, 1);
              }
            }

          } finally {
            _running--;
          }

          const done2 = [...graph.nodes.values()]
            .filter(n => n.status === "done" || n.status === "failed")
            .length;
          callbacks.onProgress?.(done2, graph.nodes.size);

          // S760-D: checkpoint dopo ogni nodo completato/fallito
          // fire-and-forget: non blocca il loop
          _checkpointGraph(graph).catch(() => {});

          // S723: checkpoint memory every 3 nodes
          if (done2 > 0 && done2 % 3 === 0 && !memoryUpdated) {
            updateMemoryFromGraph(graph).catch(() => {});
          }
        });

        await Promise.all(promises);
      }

    } finally {
      // S760-A: cleanup garantito — SEMPRE eseguito, anche su throw o abort
      // Marca i nodi "running" come "failed" e propaga "skipped" ai dipendenti
      // così lo stato finale del grafo è sempre coerente.
      if (signal?.aborted) {
        _cleanupDanglingNodes(graph, "utente ha annullato");
        callbacks.onStatus?.("Task annullato");
      } else {
        // Anche senza abort, un break inaspettato dal while può lasciare running nodes
        _cleanupDanglingNodes(graph, "loop terminato inaspettatamente");
      }
    }

    // Memory update se non già fatto via nodo dedicato
    if (!memoryUpdated) {
      try {
        await updateMemoryFromGraph(graph);
        memoryUpdated = true;
      } catch { /* non-blocking */ }
    }

    // S760-D: marca grafo come completato (cleanup Dexie)
    await _markGraphComplete(graph.id).catch(() => {});

    // S760-B: cleanup risultati offloadati su Dexie
    // fire-and-forget: rimuove le entry graphToolResults di questa run
    _getVfsDb().then(db => {
      if (!db) return;
      const idsToDelete = [...graph.nodes.values()]
        .filter(n => n.result?.startsWith(OFFLOAD_REF_PREFIX))
        .map(n => n.id);
      if (idsToDelete.length > 0) {
        // eslint-disable-next-line @typescript-eslint/no-explicit-any
        db?.graphToolResults?.bulkDelete(idsToDelete).catch(() => {});
      }
    }).catch(() => {});

    const skippedNodes = [...graph.nodes.values()]
      .filter(n => n.status === "skipped")
      .map(n => n.id);

    const success = failedNodes.length === 0 && skippedNodes.length === 0;
    const output  = await collectResultsResolved(graph);

    callbacks.onStatus?.("");

    return { success, output, toolResults, failedNodes, skippedNodes, memoryUpdated };
  }
}

export const graphOrchestrator = new GraphOrchestrator();

// ─── Graph-based planner (invariato) ─────────────────────────────────────────

export interface PlanLike {
  goal: string;
  complexity: string;
  subtasks: Array<{ tool: string; description: string; risk: string }>;
}

let _currentEpPlanOrder: string[] = [];
export function setEpPlanOrder(order: string[]): void {
  _currentEpPlanOrder = order;
}

const _FETCH_TOOLS_PG = new Set([
  "web_search", "read_page", "get_news", "search_wikipedia",
  "fetch_url", "get_stock", "get_currency", "search_github",
  "web_research",
]);
const _CODE_TOOLS_PG = new Set([
  "run_code", "write_file", "execute_shell",
  "create_webpage", "iterate_file",
]);
const _WRITE_SEQ_TOOLS = new Set([
  "write_file", "apply_patch", "iterate_file", "create_webpage",
]);

function extractToolArgs(tool: string, description?: string): Record<string, unknown> {
  const desc = (typeof description === "string" ? description : "").trim() || tool;
  if (["web_search","search_wikipedia","get_news","search_github","fetch_url","read_page","web_research"].includes(tool)) return { query: desc };
  if (tool === "run_python")    return { code: desc, language: "python" };
  if (tool === "execute_shell") return { code: desc, language: "bash" };
  if (tool === "run_code") {
    const lang =
      /\b(bash|shell|sh|zsh)\b/i.test(desc)                        ? "bash"       :
      /\b(javascript|js|node(\.?js)?|typescript|ts)\b/i.test(desc) ? "javascript" :
      /\b(ruby|rb)\b/i.test(desc)                                   ? "ruby"       :
      /\b(go|golang)\b/i.test(desc)                                 ? "go"         :
      "python";
    return { code: desc, language: lang };
  }
  if (tool === "write_file" || tool === "iterate_file") {
    const _pm = desc.match(/\b([\w./\-]+\/[\w./\-]+\.[a-zA-Z]{1,10}|[\w\-]+\.[a-zA-Z]{1,10})\b/);
    return { path: _pm?.[0] ?? "output.txt", content: desc };
  }
  if (tool === "apply_patch") {
    const _pm = desc.match(/\b([\w./\-]+\/[\w./\-]+\.[a-zA-Z]{1,10}|[\w\-]+\.[a-zA-Z]{1,10})\b/);
    return { path: _pm?.[0] ?? "output.txt", patch: desc };
  }
  if (tool === "create_webpage")  return { html: desc };
  if (["execute_sql","database_query"].includes(tool)) return { query: desc };
  if (["generate_image"].includes(tool)) return { prompt: desc };
  if (tool === "get_weather") {
    const _cm = desc.match(/\b(?:a|in|per|for|at)\s+([A-Za-z\u00c0-\u00ff][A-Za-z\u00c0-\u00ff\s]{1,24}?)(?:\s*[?,.]|$|\s+(?:oggi|ora|adesso|now|today|domani|tomorrow))/i);
    return { city: (_cm?.[1]?.trim() ?? desc.slice(0, 50)).trim() };
  }
  if (["get_stock","get_currency","get_datetime","get_ip_info","math_eval"].includes(tool)) return { query: desc };
  if (tool === "call_api") {
    const _urlM  = desc.match(/https?:\/\/[^\s"'<>]+/i);
    const _methM = desc.match(/\b(GET|POST|PUT|PATCH|DELETE)\b/i);
    return { url: _urlM?.[0] ?? "", method: (_methM?.[1]?.toUpperCase() ?? "GET") as "GET"|"POST"|"PUT"|"PATCH"|"DELETE" };
  }
  if (tool === "send_email") {
    const _toM   = desc.match(/\b[\w.+\-]+@[\w.\-]+\.[a-z]{2,}\b/i);
    const _subjM = desc.match(/(?:oggetto|subject|re)\s*[:\-]\s*([^\n]+)/i);
    return { to: _toM?.[0] ?? "", subject: _subjM?.[1]?.trim() ?? desc.slice(0, 60), body: desc };
  }
  if (tool === "create_pdf") {
    const _slug = desc.slice(0, 40).trim().toLowerCase()
      .replace(/[^a-z0-9àèìòùáéíóú]+/g, "_").replace(/^_|_$/g, "").slice(0, 35) || "documento";
    return { content: desc, filename: `${_slug}.pdf` };
  }
  return { input: desc };
}

export function planToGraph(plan: PlanLike): TaskGraph {
  const _epOrderSnapshot = [..._currentEpPlanOrder];
  _currentEpPlanOrder = [];

  const steps = plan.subtasks.filter(s => s.tool !== "respond");
  let _lastWriteIdx: number | undefined;

  return buildGraph({
    goal: plan.goal,
    steps: steps.map((s, i, arr) => {
      let dependsOn: number[] | undefined;
      if (i > 0 && _CODE_TOOLS_PG.has(s.tool)) {
        for (let j = i - 1; j >= 0; j--) {
          if (_FETCH_TOOLS_PG.has(arr[j].tool)) { dependsOn = [j]; break; }
        }
      }
      if (_WRITE_SEQ_TOOLS.has(s.tool)) {
        if (_lastWriteIdx !== undefined) {
          dependsOn = dependsOn
            ? [...new Set([...dependsOn, _lastWriteIdx])]
            : [_lastWriteIdx];
        }
        _lastWriteIdx = i;
      }
      const _epPos = _epOrderSnapshot.length > 0
        ? (() => {
            const label = s.description?.toLowerCase() ?? "";
            const idx   = _epOrderSnapshot.findIndex(
              p => label.includes(p.toLowerCase()) || p.toLowerCase().includes(label.slice(0, 20))
            );
            return idx === -1 ? 999 : idx;
          })()
        : 999;
      return {
        tool:      s.tool,
        label:     (s.description ?? "").slice(0, 150),  // S609: 80→150
        input:     extractToolArgs(s.tool, s.description),
        dependsOn,
        verify:    s.risk === "high",
        priority:  _epPos,
      };
    }),
    synthesize: true,
    memorize:   plan.complexity !== "low",
  });
}