// module-world-model.js — Global World Model: system self-awareness synthesis engine
// Aggregates from memory graph, neural VFS, skills index, telemetry
// Commands: world-model, world-model-summary, world-model-ask (LLM), world-model-refresh, world-model-config
class WorldModelModule {
    constructor() {
        this.commands = {};
        this.terminal = null;
        this._model = null;
        this._lastRefresh = null;
        this._REFRESH_INTERVAL = 300000; // 5 minutes (fallback)
        this._MAX_PROJECTS = 10;
        this._refreshTimer = null;
        // v4.5.89: Event-driven sync state
        this._syncDebounce = null;
        this._syncing = false;
        this._lastEventSync = 0;
        this._EVENT_DEBOUNCE_MS = 500;
    }

    getHelpInfo() {
        return {
            'world-model': 'world-model — Show full world model as structured output',
            'world-model-summary': 'world-model-summary — One-line system self-awareness statement',
'world-model-ask': 'world-model-ask <question> — Ask the LLM about this system (grounded in the world model; --facts for the instant keyword lookup)',
            'world-model-refresh': 'world-model-refresh — Force re-synthesis from all subsystems',
            'world-model-config': 'world-model-config <key> <value> — Tune: refresh-interval, max-projects',
        };
    }

    registerCommands() {
        this.commands['world-model'] = () => this.showModel();
        this.commands['world-model-summary'] = () => this.showSummary();
        this.commands['world-model-ask'] = (args) => this.ask(args.join(' '));
        this.commands['world-model-refresh'] = () => this.refresh();
        this.commands['world-model-config'] = (args) => this.setConfig(args);
    }

    init(terminal) {
        this.terminal = terminal;
        this._loadFromVFS();
        // Deferred initial synthesis — wait for ext modules (SkillPackCore etc) to fully load
        setTimeout(() => {
            this._synthesize();
            this.terminal.print('🌐 World Model synthesized — system self-awareness active', 'info');
            // Second pass after ext modules definitely finished loading
            setTimeout(() => {
                this._synthesize();
                this.terminal.print('🌐 World Model refresh — full module load confirmed', 'info');
            }, 7000);
        }, 5000);
        // Auto-refresh on a timer
        this._refreshTimer = setInterval(() => {
            const age = Date.now() - (this._lastRefresh ? new Date(this._lastRefresh).getTime() : 0);
            if (age > this._REFRESH_INTERVAL) this._synthesize();
        }, this._REFRESH_INTERVAL);
        this.terminal.print('🌐 World Model loaded — system self-awareness active', 'info');
    }

    // v4.5.89: Event-driven sync — debounced, recursion-guarded
    _scheduleSync() {
        if (this._syncing) return; // Prevent recursion during active synthesis
        if (this._syncDebounce) clearTimeout(this._syncDebounce);
        const now = Date.now();
        // Skip if we synced < 2s ago (rate limit beyond debounce)
        if (now - this._lastEventSync < 2000) return;
        this._syncDebounce = setTimeout(() => {
            this._syncDebounce = null;
            this._syncing = true;
            try {
                this._synthesize();
                this._lastEventSync = Date.now();
            } finally {
                this._syncing = false;
            }
        }, this._EVENT_DEBOUNCE_MS);
    }

    // ─── Synthesis Engine ───

    _synthesize() {
        try {
            const fs = this.terminal.fs;
            if (!fs) return;

            // Derive version from actual system state — no hardcoded strings
            const mInfo = this._gatherModuleInfo();
            const agentInfo = this._gatherAgentInfo();
            const fileInfo = this._gatherFileInfo(fs);
            const skillInfo = this._gatherSkillInfo(fs);
            const liveVersion = this._deriveVersion(mInfo);

            const model = {
                version: liveVersion,
                synthesized: new Date().toISOString(),
                system: this._gatherSystemInfo(fs, mInfo.loaded, liveVersion),
                modules: mInfo,
                files: fileInfo,
                skills: skillInfo,
                memory: this._gatherMemoryInfo(),
                agents: agentInfo,
                telemetry: this._gatherTelemetry(fs),
                projects: this._gatherProjects(fs),
                recent: this._gatherRecent(fs)
            };

            this._model = model;
            this._lastRefresh = model.synthesized;
            this._saveToVFS(fs);

            // Log synthesis summary
            const mCount = model.modules?.loaded || '?';
            const sCount = model.skills?.count || '?';
            const fCount = model.files?.total || '?';
            console.log(`[WorldModel] Synthesis complete: ${mCount} modules, ${sCount} skills, ${fCount} files`);
        } catch (e) {
            console.error('[WorldModel] Synthesis error:', e.message);
        }
    }

    _deriveVersion(mInfo) {
        // Single source of truth: the constant set at bootstrap
        if (window.NEWOS4_VERSION) return window.NEWOS4_VERSION;
        // Fallback: try to extract from script tag ?v= query param or LATEST_VER constant
        try {
            const scripts = document.querySelectorAll('script[src*="module-loader"]');
            for (const s of scripts) {
                const match = s.src.match(/[?&]v=([^&]+)/);
                if (match) return match[1];
            }
            // Try to find LATEST_VER in any inline script
            const allScripts = document.querySelectorAll('script:not([src])');
            for (const s of allScripts) {
                const match = s.textContent.match(/LATEST_VER\s*=\s*['"]([^'"]+)['"]/);
                if (match) return match[1];
            }
        } catch (e) {
            console.warn('[WorldModel] Version extraction error:', e.message);
        }
        return 'v?';
    }

    _getTotalModules() {
        try {
            const mm = this.terminal?.moduleManager;
            if (!mm) return 0;
            // Use max of registry vs loaded so the ratio is never >1 (e.g. 43/7 → 43/43)
            const loadedCount = Object.keys(mm.modules || {}).length;
            const registryCount = (mm.moduleRegistry || []).length;
            return Math.max(loadedCount, registryCount);
        } catch (e) {
            console.warn('[WorldModel] Total modules gather error:', e.message);
            return Object.keys(this.terminal?.moduleManager?.modules || {}).length || 0;
        }
    }

    _gatherSystemInfo(fs, moduleCount, version) {
        // Get real health data from ServerMonitorModule's _latencyLog and DebugSupervisorModule
        const sm = this.terminal?.moduleManager?.modules?.['ServerMonitorModule'];
        const ds = this.terminal?.moduleManager?.modules?.['DebugSupervisorModule'];
        const errorCount = ds ? Object.keys(ds._errorDB?.errors || {}).length : 0;
        const latencyErrors = sm?._latencyLog ? Object.values(sm._latencyLog).filter(e => e.status === 'error').length : 0;
        const totalErrors = errorCount + latencyErrors;
        return {
            version: `newOS4 ${version}`,
            modules: moduleCount || Object.keys(this.terminal?.moduleManager?.modules || {}).length || 0,
            vfsSize: JSON.stringify(fs?.root || {}).length,
            online: typeof navigator !== 'undefined' ? navigator.onLine : true,
            memory: typeof performance !== 'undefined' && performance.memory
                ? `${(performance.memory.usedJSHeapSize / 1048576).toFixed(1)}MB`
                : 'N/A',
            health: totalErrors > 0 ? `⚠️ ${totalErrors} errors` : 'OK',
            lastHealthCheck: new Date().toISOString()
        };
    }

    _gatherModuleInfo() {
        const mm = this.terminal?.moduleManager;
        if (!mm) return { loaded: 0, modified: [] };
        const modules = Object.keys(mm.modules || {}).map(name => {
            const mod = mm.modules[name];
            const clsName = mod?.constructor?.name || name;
            return { name: clsName, hasCommands: !!mod?.commands };
        });
        // Check for local modifications
        const modsDir = this.terminal.fs?.readDir('/_mods/');
        const modified = modsDir
            ? modsDir.filter(e => e.type === 'file' && e.name.endsWith('.js') && !e.name.endsWith('.orig.js'))
                .map(e => e.name.replace('.js', ''))
            : [];
        return {
            loaded: modules.length,
            total: this._getTotalModules(),
            modules,
            modified,
            modifiedCount: modified.length
        };
    }

    _gatherFileInfo(fs) {
        if (!fs) return { total: 0, size: '0KB' };
        let fileCount = 0, dirCount = 0;
        const walk = (path) => {
            const entries = fs.ls(path);
            if (!entries) return;
            for (const e of entries) {
                if (e.type === 'file') fileCount++;
                else { dirCount++; walk(path === '/' ? '/' + e.name : path + '/' + e.name); }
            }
        };
        walk('/');
        return {
            total: fileCount,
            directories: dirCount,
            size: `${(JSON.stringify(fs.root).length / 1024).toFixed(1)}KB`
        };
    }

    _gatherSkillInfo(fs) {
        try {
            const idx = fs.fsReadJSON('/skills/index.json');
            const count = idx ? Object.keys(idx).length : 0;
            return { count, skills: idx ? Object.keys(idx) : [] };
        } catch (e) {
            console.warn('[WorldModel] Skill info gather error:', e.message);
            return { count: 0, skills: [] };
        }
    }

    _gatherMemoryInfo() {
        const mg = this.terminal?.moduleManager?.modules?.['MemoryGraphModule'];
        if (mg && mg._nodes) {
            const nodes = Object.keys(mg._nodes).length;
            const edges = (mg._edges || []).length;
            return { nodes, edges, active: true, fallback: false };
        }
        // Fallback: count memory files
        try {
            const memIndex = this.terminal.fs?.fsReadJSON('/memory/index.json');
            return { nodes: memIndex ? Object.keys(memIndex).length : 0, edges: 0, active: false, fallback: true };
        } catch (e) {
            console.warn('[WorldModel] Memory info gather error:', e.message);
            return { nodes: 0, edges: 0, active: false, fallback: true };
        }
    }

    _gatherAgentInfo() {
        const orch = this.terminal?.moduleManager?.modules?.['OrchestratorModule'];
        if (!orch || !orch._agents) return { agents: -1, active: -1, error: 'Orchestrator not loaded' };
        const agents = Object.keys(orch._agents).length;
        const active = Object.values(orch._agents).filter(a => a.status === 'busy').length;
        return { agents, active, totalLeases: Object.keys(orch._a2aMessages || {}).length };
    }

    _gatherTelemetry(fs) {
        try {
            // Get real latency data from ServerMonitorModule and errors from DebugSupervisorModule
            const sm = this.terminal?.moduleManager?.modules?.['ServerMonitorModule'];
            const ds = this.terminal?.moduleManager?.modules?.['DebugSupervisorModule'];
            const latencyDataPoints = sm?._latencyLog ? Object.keys(sm._latencyLog).length : 0;
            const recentErrors = ds ? Object.keys(ds._errorDB?.errors || {}).length : 0;
            return {
                toolLatencyDataPoints: latencyDataPoints,
                recentErrors: recentErrors,
            };
        } catch (e) {
            console.warn('[WorldModel] Telemetry gather error:', e.message);
            return { toolLatencyDataPoints: 0, recentErrors: 0 };
        }
    }

    _gatherProjects(fs) {
        try {
            const mg = this.terminal?.moduleManager?.modules?.['MemoryGraphModule'];
            if (mg && mg._nodes) {
                // Find task clusters as "projects"
                const tasks = Object.values(mg._nodes).filter(n => n.type === 'task');
                const recentFiles = Object.values(mg._nodes)
                    .filter(n => n.type === 'file')
                    .sort((a, b) => (b.access_count || 0) - (a.access_count || 0))
                    .slice(0, this._MAX_PROJECTS);
                return {
                    totalTasks: tasks.length,
                    activeProjects: recentFiles.slice(0, 5).map(f => ({
                        name: f.label,
                        accesses: f.access_count || 0,
                        lastModified: f.updated
                    }))
                };
            }
            return { totalTasks: 0, activeProjects: [] };
        } catch (e) {
            console.warn('[WorldModel] Projects gather error:', e.message);
            return { totalTasks: 0, activeProjects: [] };
        }
    }

    _gatherRecent(fs) {
        const recent = [];
        try {
            // Check modified modules
            const modsDir = fs.readDir('/_mods/');
            if (modsDir) {
                for (const e of modsDir) {
                    if (e.type === 'file' && e.name.endsWith('.js') && !e.name.endsWith('.orig.js') && !e.name.endsWith('.meta.json')) {
                        recent.push(`Modified module: ${e.name.replace('.js', '')}`);
                    }
                }
            }
            // Check skills activity
            const skills = fs.ls('/skills/');
            if (skills && skills.length > 0) {
                recent.push(`Skills directory: ${skills.filter(s => s.type === 'file').length} files`);
            }
            // Check memory directory for recent changes
            const memDir = fs.readDir('/memory/');
            if (memDir && memDir.length > 0) {
                const memFiles = memDir.filter(s => s.type === 'file');
                if (memFiles.length > 0) {
                    recent.push(`Memory: ${memFiles.length} files in /memory/`);
                }
            }
            // Check system config changes
            const sysDir = fs.readDir('/system/');
            if (sysDir && sysDir.length > 0) {
                const configFiles = sysDir.filter(s => s.type === 'file' && s.name.endsWith('.json'));
                if (configFiles.length > 0) {
                    recent.push(`System config: ${configFiles.length} config files`);
                }
            }
        } catch (e) {
            console.warn('[WorldModel] Recent gather error:', e.message);
        }
        return recent;
    }

    // ─── Commands ───

    showModel() {
        if (!this._model) return this.terminal.print('No model yet — run world-model-refresh', 'warning');
        const m = this._model;

        this.terminal.print('🌐 World Model', 'header');
        this.terminal.print(`  Version: ${m.version} (last synthsized: ${new Date(m.synthesized).toLocaleTimeString()})`, 'info');

        this.terminal.print(`  ⚙️  System — ${m.system.modules} modules loaded, ${m.system.vfsSize} VFS, ${m.system.memory}`, 'info');
        this.terminal.print(`  🧩 Modules — ${m.modules.loaded} loaded (${m.modules.modifiedCount} modified)`, 'info');
        this.terminal.print(`  📁 Files — ${m.files.total} files, ${m.files.directories} dirs, ${m.files.size}`, 'info');
        this.terminal.print(`  📚 Skills — ${m.skills.count} installed`, 'info');
        this.terminal.print(`  🧠 Memory Graph — ${m.memory.nodes} nodes, ${m.memory.edges} edges${m.memory.active ? ' ✅' : ''}`, 'info');
        this.terminal.print(`  🤖 Agents — ${m.agents.agents} registered (${m.agents.active} active)`, 'info');
        this.terminal.print(`  📊 Telemetry — ${m.telemetry.toolLatencyDataPoints} tool latency points, ${m.telemetry.recentErrors} recent errors`, 'info');

        if (m.projects.activeProjects.length > 0) {
            this.terminal.print('  Active context:', 'header');
            for (const p of m.projects.activeProjects.slice(0, 3)) {
                this.terminal.print(`    📌 ${p.name} (${p.accesses}x accesses)`, 'info');
            }
        }

        if (m.recent.length > 0) {
            this.terminal.print('  Recent changes:', 'header');
            for (const r of m.recent.slice(0, 3)) {
                this.terminal.print(`    ${r}`, 'info');
            }
        }
    }

    showSummary() {
        if (!this._model) return this.terminal.print('No model yet', 'warning');
        const m = this._model;
        const summary = `newOS4 ${m.version} · ${m.modules.loaded}/${m.modules.total} modules · ${m.skills.count} skills · ${m.files.total} files · ${m.agents.agents} agents · ${m.memory.nodes} graph nodes · ${m.telemetry.recentErrors > 0 ? `⚠️ ${m.telemetry.recentErrors} errors` : '✅ OK'}`;
        this.terminal.print(summary, 'info');
        return summary;
    }

    async ask(question) {
        if (!question) return this.terminal.print('Usage: world-model-ask <question>   (--facts = fast keyword lookup)', 'error');
        const factsOnly = /(^|\s)--facts\b/.test(question);
        if (factsOnly) question = question.replace(/--facts\b/, '').trim();
        if (!this._model) return this.terminal.print('No model — run world-model-refresh first', 'warning');

        this.terminal.print(`❓ ${question}`, 'info');

        if (!factsOnly) {
            const om = this.terminal.ollamaManager;
            try {
                if (om && !om.connected) { try { await om.connect(); } catch (e) {} }
                if (om && om.connected) {
                    const answer = await om.chat(this._buildAskPrompt(question));
                    if (answer && String(answer).trim()) {
                        this.terminal.print(`💡 ${String(answer).trim()}`, 'success');
                        return;
                    }
                }
            } catch (e) { /* fall through to the facts path */ }
            this.terminal.print('⚠️ LLM unavailable — showing the factual lookup instead', 'warning');
        }

        this.terminal.print(`💡 ${this._answerQuery(question)}`, 'success');
    }

    // Shared query routing — used by both ask() (terminal) and world_model_query (AI tool)
    _answerQuery(question) {
        if (!this._model) return 'World model not synthesized yet — run world-model-refresh';
        const q = (question || '').toLowerCase();
        const m = this._model;

        if (q.includes('module') || q.includes('loaded')) {
            return `Loaded ${m.modules.loaded} modules (${m.modules.modifiedCount} modified: ${m.modules.modified.join(', ') || 'none'})`;
        } else if (q.includes('skill')) {
            return `Installed ${m.skills.count} skills: ${m.skills.skills.join(', ') || 'none'}`;
        } else if (q.includes('file') || q.includes('vfs')) {
            return `${m.files.total} files in ${m.files.directories} directories, total ${m.files.size}`;
        } else if (q.includes('agent') || q.includes('orchestrat')) {
            return `${m.agents.agents} agents (${m.agents.active} active)`;
        } else if (q.includes('health') || q.includes('status')) {
            return `Health: ${m.system.health} · Memory: ${m.system.memory} · ${m.telemetry.recentErrors > 0 ? `${m.telemetry.recentErrors} recent errors` : 'No errors'}`;
        } else if (q.includes('memory') || q.includes('graph')) {
            return `Memory Graph: ${m.memory.nodes} nodes, ${m.memory.edges} edges (${m.memory.active ? 'active' : 'inactive'})`;
        } else if (q.includes('change') || q.includes('yesterday') || q.includes('recent')) {
            const diff = this._diffSincePrev();
            const recent = m.recent || [];
            const parts = [];
            if (diff.length) parts.push('Since the last snapshot: ' + diff.join('; '));
            if (recent.length) parts.push('Current: ' + recent.join('; '));
            return parts.length ? parts.join(' · ') : 'No previous snapshot yet — run world-model-refresh twice';
        } else if (q.includes('project') || q.includes('work')) {
            const projects = m.projects.activeProjects;
            return projects.length > 0
                ? `Active projects: ${projects.map(p => `${p.name} (${p.accesses}x)`).join(', ')}`
                : 'No active projects detected';
        } else if (q.includes('telemetry') || q.includes('latency')) {
            return `${m.telemetry.toolLatencyDataPoints} tool latency data points tracked, ${m.telemetry.recentErrors} recent errors`;
        } else if (q.includes('summary') || q.includes('overview') || q.includes('all')) {
            return `newOS4 ${m.version} · ${m.modules.loaded}/${m.modules.total} modules · ${m.skills.count} skills · ${m.files.total} files · ${m.agents.agents} agents · ${m.memory.nodes} graph nodes · ${m.telemetry.recentErrors > 0 ? `⚠️ ${m.telemetry.recentErrors} errors` : '✅ OK'}`;
        } else {
            return `Unknown query. Try: modules, skills, files, agents, health, memory, changes, projects, telemetry, or summary.`;
        }
    }

    // 2026-10-21: ask() used to be a keyword table only, so any real question got
    // "Unknown query". Whitelist the fields we are willing to send to a model
    // (never the raw model object: it is persisted alongside other VFS data).
    _modelDigest(maxChars) {
        const m = this._model;
        if (!m) return '';
        const cap = maxChars || 4000;
        const pick = {
            version: m.version,
            synthesized: m.synthesized,
            system: m.system,
            modules: m.modules,
            files: m.files,
            skills: { count: m.skills && m.skills.count, skills: ((m.skills && m.skills.skills) || []).slice(0, 40) },
            memory: m.memory,
            agents: m.agents,
            telemetry: m.telemetry,
            projects: m.projects,
            recent: (m.recent || []).slice(0, 20),
            // 2026-10-21: the model only ever exposed a COUNT ("9 recent errors") with no detail,
            // so neither the user nor the LLM could say what failed. Carry the last few.
            recentErrorSample: this._errorSample ? this._errorSample() : [],
            changesSinceLastSnapshot: this._diffSincePrev ? this._diffSincePrev() : []
        };
        let json = JSON.stringify(pick);
        if (json.length > cap) json = json.slice(0, cap) + '…(digest truncated)';
        return json;
    }

    // Last few tool/agent errors with their tool name, for the digest (bounded).
    _errorSample() {
        try {
            const ds = this.terminal.moduleManager.modules['DebugSupervisorModule'];
            const db = ds && ds._errorDB && ds._errorDB.errors;
            if (!db) return [];
            return Object.keys(db).slice(-5).map(k => {
                const e = db[k] || {};
                return String(e.tool || e.module || k).slice(0, 40) + ': ' + String(e.error || e.message || '').slice(0, 80);
            });
        } catch (e) { return []; }
    }

    _buildAskPrompt(question) {
        return [
            'You are the newOS4 world model interface. Answer ONLY from the JSON snapshot below.',
            'If the snapshot does not contain the answer, say what is missing and name the command that',
            'would produce it (world-model-refresh, world-model, modules, test). Never invent numbers.',
            'Answer in 1-3 short sentences, plain text, no markdown headers.',
            '',
            'SNAPSHOT: ' + this._modelDigest(),
            '',
            'QUESTION: ' + String(question || '').trim()
        ].join('\n');
    }

    _diffSincePrev() {
        try {
            const fs = this.terminal.fs;
            const prev = fs && fs.fsReadJSON('/system/world-model.prev.json');
            const cur = this._model;
            if (!prev || !cur) return [];
            const out = [];
            if (prev.version && cur.version && prev.version !== cur.version) out.push(`version ${prev.version} → ${cur.version}`);
            const fields = [['modules', 'loaded'], ['skills', 'count'], ['files', 'total'], ['agents', 'agents'], ['memory', 'nodes']];
            fields.forEach(function (f) {
                const a = prev[f[0]] && prev[f[0]][f[1]];
                const b = cur[f[0]] && cur[f[0]][f[1]];
                if (typeof a === 'number' && typeof b === 'number' && a !== b) out.push(`${f[0]} ${a} → ${b}`);
            });
            if (prev.synthesized) out.push('previous snapshot: ' + prev.synthesized);
            return out;
        } catch (e) { return []; }
    }

    refresh() {
        this._synthesize();
        this.terminal.print(`✅ World Model refreshed at ${new Date().toLocaleTimeString()}`, 'success');
    }

    setConfig(args) {
        if (args.length < 2) return this.terminal.print('Usage: world-model-config <key> <value>', 'error');
        const key = args[0];
        const val = args[1];

        const configMap = {
            'refresh-interval': () => {
                const n = parseInt(val) * 1000;
                if (isNaN(n) || n < 10000) return 'Must be >= 10 seconds';
                this._REFRESH_INTERVAL = n;
                if (this._refreshTimer) clearInterval(this._refreshTimer);
                this._refreshTimer = setInterval(() => this._synthesize(), n);
                return `refresh-interval set to ${val}s`;
            },
            'max-projects': () => {
                const n = parseInt(val);
                if (isNaN(n) || n < 1) return 'Must be >= 1';
                this._MAX_PROJECTS = n;
                return `max-projects set to ${n}`;
            },
        };

        if (!configMap[key]) return this.terminal.print(`Unknown: ${key}. Valid: ${Object.keys(configMap).join(', ')}`, 'error');
        const msg = configMap[key]();
        this.terminal.print(`✅ ${msg}`, 'success');
    }

    // ─── Context Injection ───

    getContextForPrompt() {
        if (!this._model) return '';
        const m = this._model;
        const agentStr = m.agents.error
            ? 'agents: N/A'
            : `${m.agents.agents} agents`;
        return `[World Model Context]\nSystem: newOS4 ${m.version} · ${m.modules.loaded} modules · ${m.skills.count} skills · ${m.files.total} files · ${agentStr}${m.telemetry.recentErrors > 0 ? ` · ⚠️ ${m.telemetry.recentErrors} errors` : ' · ✅ OK'}${m.modules.modifiedCount > 0 ? `\nModified modules: ${m.modules.modified.slice(0, 3).join(', ')}${m.modules.modifiedCount > 3 ? ` (+${m.modules.modifiedCount - 3} more)` : ''}` : ''}`;
    }

    // ─── Persistence ───

    _loadFromVFS() {
        try {
            const fs = this.terminal.fs;
            if (!fs) return;
            const data = fs.fsReadJSON('/system/world-model.json');
            if (data) {
                this._model = data;
                this._lastRefresh = data.synthesized;
            }
        } catch (e) {
            console.warn('[WorldModel] Load error (fresh start):', e.message);
        }
    }

    // v4.5.89: Atomic write — temp file + rename to prevent corruption
    _saveToVFS(fs) {
        try {
            if (!fs.readDir('/system')) fs.mkdir('system');
            // 2026-10-21: keep one previous model so "what changed" can be a real diff.
            const prevModel = fs.fsReadJSON('/system/world-model.json');
            if (prevModel) { try { fs.fsWriteJSON('/system/world-model.prev.json', prevModel); } catch (_) {} }
            // v4.5.89b fix: Clean stale temp from previous crash (P1 from review)
            try { fs.deleteFile('/system/world-model.tmp.json'); } catch (_) {}
            fs.fsWriteJSON('/system/world-model.tmp.json', this._model);
            const tmp = fs.fsReadJSON('/system/world-model.tmp.json');
            if (tmp) {
                fs.fsWriteJSON('/system/world-model.json', tmp);
                fs.deleteFile('/system/world-model.tmp.json');
            } else {
                console.error('[WorldModel] Save failed: temp file corrupt after write');
            }
        } catch (e) {
            console.error('[WorldModel] Save error:', e.message);
        }
    }
}

// Required for module system
if (typeof window !== 'undefined') {
    window.WorldModelModule = WorldModelModule;
}