// ==UserScript==
// @name         12345 AI Native Track Copilot
// @namespace    http://tampermonkey.net/
// @version      1.0
// @description  Native-track only bridge: no WebAudio washing, no captureStream, no MediaStreamDestination.
// @author       You
// @match        *://yhy-yw.22sj.cn:*/*
// @grant        none
// @run-at       document-start
// ==/UserScript==

(function () {
    'use strict';

    const DEFAULT_SIGNALING_URL = 'ws://182.92.86.220:8000/ws/voice';
    const AUDIO_UPLINK_STORAGE_KEY = 'native-copilot-send-audio';
    const VIDEO_UPLINK_STORAGE_KEY = 'native-copilot-send-video';

    const originalGetUserMedia = navigator.mediaDevices?.getUserMedia?.bind(navigator.mediaDevices);
    const originalAddEventListener = RTCPeerConnection.prototype.addEventListener;
    const originalAddTrack = RTCPeerConnection.prototype.addTrack;
    const originalAddTransceiver = RTCPeerConnection.prototype.addTransceiver;
    const originalSetRemoteDescription = RTCPeerConnection.prototype.setRemoteDescription;
    const mediaSrcObjectDescriptor = Object.getOwnPropertyDescriptor(HTMLMediaElement.prototype, 'srcObject');

    const remoteStreams = new Set();
    const ignoredTrackIds = new Set();
    const audioCandidates = new Map();
    const videoCandidates = new Map();
    const businessSenderCandidates = new Map();
    const localCaptureTrackIds = new Set();
    window.__aiNativeCopilotReceivers = window.__aiNativeCopilotReceivers || new Set();

    let aiPc = null;
    let aiWs = null;
    let aiDc = null;
    let aiAudioSender = null;
    let aiVideoSender = null;

    let businessAudioSender = null;
    let businessOriginalAudioTrack = null;

    let remoteUserAudioTrack = null;
    let remoteUserVideoTrack = null;
    let aiResponseAudioTrack = null;
    let remoteUserAudioLocked = false;
    let remoteUserVideoLocked = false;

    let isAiTakeover = false;
    let aiTrackAttachedToBusiness = false;
    let inputVuLevel = 0;
    let aiOutVuLevel = 0;
    let aiInputHealthTimer = null;
    let aiOutputHealthTimer = null;
    let assistantLine = null;
    let assistantBuffer = '';
    let inputRecorder = null;
    let inputRecordingChunks = [];
    let inputRecordingTrack = null;
    let inputRecordingStartedAt = 0;
    let videoRecorder = null;
    let videoRecordingChunks = [];
    let videoRecordingTrack = null;
    let videoRecordingStartedAt = 0;

    const receiverStatsMemory = new Map();
    const senderStatsMemory = new Map();
    const inboundStatsMemory = new Map();
    const outboundStatsMemory = new Map();
    const businessOutboundStats = {
        bytesSent: 0,
        packetsSent: 0,
        bytesDelta: 0,
        packetsDelta: 0,
    };

    function log(message) {
        console.log(`[AI Native Copilot] ${message}`);
    }

    function readBoolSetting(key, fallback) {
        try {
            const value = localStorage.getItem(key);
            if (value === null) return fallback;
            return value === 'true';
        } catch {
            return fallback;
        }
    }

    function writeBoolSetting(key, value) {
        try {
            localStorage.setItem(key, value ? 'true' : 'false');
        } catch {
            // Keep the live checkbox state even if storage is unavailable.
        }
    }

    function shouldSendAudioToAi() {
        return readBoolSetting(AUDIO_UPLINK_STORAGE_KEY, true);
    }

    function shouldSendVideoToAi() {
        return readBoolSetting(VIDEO_UPLINK_STORAGE_KEY, true);
    }

    function appendChatLine(role, text, important = false) {
        const box = document.getElementById('native-copilot-log');
        if (!box) return;
        if (box.children.length === 1 && box.children[0].dataset.placeholder) box.innerHTML = '';

        const row = document.createElement('div');
        row.textContent = `[${new Date().toLocaleTimeString([], { hour12: false })}] ${role}: ${text}`;
        row.style.marginBottom = '4px';
        if (important) row.style.color = '#fcd34d';
        box.appendChild(row);
        while (box.children.length > 120) box.removeChild(box.firstChild);
        box.scrollTop = box.scrollHeight;
        return row;
    }

    function startAssistantLine() {
        assistantBuffer = '';
        assistantLine = null;
    }

    function appendAssistantDelta(delta) {
        if (!delta) return;
        const box = document.getElementById('native-copilot-log');
        if (!box) {
            console.log(`[AI Native Copilot] AI: ${delta}`);
            return;
        }
        if (box.children.length === 1 && box.children[0].dataset.placeholder) box.innerHTML = '';
        if (!assistantLine) assistantLine = appendChatLine('AI', '');
        assistantBuffer += delta;
        assistantLine.textContent = `[${new Date().toLocaleTimeString([], { hour12: false })}] AI: ${assistantBuffer}`;
        box.scrollTop = box.scrollHeight;
    }

    function finishAssistantLine() {
        assistantLine = null;
        assistantBuffer = '';
    }

    function logUserTranscript(text) {
        if (!text?.trim()) return;
        finishAssistantLine();
        appendChatLine('用户', text.trim(), true);
    }

    function recorderMimeType() {
        if (window.MediaRecorder?.isTypeSupported?.('audio/webm;codecs=opus')) return 'audio/webm;codecs=opus';
        if (window.MediaRecorder?.isTypeSupported?.('audio/webm')) return 'audio/webm';
        return '';
    }

    function recordingFileName(track) {
        const stamp = new Date().toISOString().replace(/[:.]/g, '-');
        const trackPart = track?.id ? track.id.slice(0, 8) : 'no-track';
        return `native-ai-input-${trackPart}-${stamp}.webm`;
    }

    function videoRecordingFileName(track) {
        const stamp = new Date().toISOString().replace(/[:.]/g, '-');
        const trackPart = track?.id ? track.id.slice(0, 8) : 'no-track';
        return `native-ai-video-${trackPart}-${stamp}.webm`;
    }

    function updateRecordButton() {
        const button = document.getElementById('native-copilot-record');
        if (!button) return;
        const recording = inputRecorder?.state === 'recording';
        button.textContent = recording ? '停止录制 AI 输入' : '录制 AI 输入';
        button.style.background = recording ? '#dc2626' : '#2563eb';
    }

    function videoRecorderMimeType() {
        if (window.MediaRecorder?.isTypeSupported?.('video/webm;codecs=vp8')) return 'video/webm;codecs=vp8';
        if (window.MediaRecorder?.isTypeSupported?.('video/webm')) return 'video/webm';
        return '';
    }

    function updateVideoRecordButton() {
        const button = document.getElementById('native-copilot-record-video');
        if (!button) return;
        const recording = videoRecorder?.state === 'recording';
        button.textContent = recording ? '停止录制 AI 视频' : '录制 AI 视频';
        button.style.background = recording ? '#dc2626' : '#475569';
    }

    async function startInputRecording() {
        if (inputRecorder?.state === 'recording') return;
        chooseRemoteAudioTrack('record');
        if (!isUsableTrack(remoteUserAudioTrack)) {
            appendChatLine('录音', '没有可录制的 AI 输入音轨', true);
            return;
        }
        if (!window.MediaRecorder) {
            appendChatLine('录音', '当前浏览器不支持 MediaRecorder', true);
            return;
        }

        inputRecordingChunks = [];
        inputRecordingTrack = remoteUserAudioTrack;
        inputRecordingStartedAt = Date.now();
        const stream = new MediaStream([inputRecordingTrack]);
        const mimeType = recorderMimeType();
        inputRecorder = new MediaRecorder(stream, mimeType ? { mimeType } : undefined);
        inputRecorder.ondataavailable = (event) => {
            if (event.data?.size > 0) inputRecordingChunks.push(event.data);
        };
        inputRecorder.onstop = () => {
            const blob = new Blob(inputRecordingChunks, { type: inputRecorder?.mimeType || 'audio/webm' });
            const url = URL.createObjectURL(blob);
            const link = document.createElement('a');
            link.href = url;
            link.download = recordingFileName(inputRecordingTrack);
            document.body.appendChild(link);
            link.click();
            link.remove();
            setTimeout(() => URL.revokeObjectURL(url), 30000);

            const seconds = ((Date.now() - inputRecordingStartedAt) / 1000).toFixed(1);
            appendChatLine('录音', `已保存 ${link.download}（${seconds}s，${(blob.size / 1024).toFixed(1)} KB）`, true);
            inputRecorder = null;
            inputRecordingChunks = [];
            inputRecordingTrack = null;
            updateRecordButton();
        };
        inputRecorder.start(250);
        appendChatLine('录音', `开始录制 AI 输入：${describeTrack(inputRecordingTrack)}`, true);
        updateRecordButton();
    }

    function stopInputRecording() {
        if (inputRecorder?.state === 'recording') inputRecorder.stop();
    }

    function toggleInputRecording() {
        if (inputRecorder?.state === 'recording') stopInputRecording();
        else startInputRecording();
    }

    async function startVideoRecording() {
        if (videoRecorder?.state === 'recording') return;
        chooseRemoteVideoTrack('record-video');
        if (!remoteUserVideoLocked || !isUsableTrack(remoteUserVideoTrack)) {
            appendChatLine('录制视频', '没有可录制的上半部用户视频轨', true);
            return;
        }
        if (!window.MediaRecorder) {
            appendChatLine('录制视频', '当前浏览器不支持 MediaRecorder', true);
            return;
        }

        videoRecordingChunks = [];
        videoRecordingTrack = remoteUserVideoTrack;
        videoRecordingStartedAt = Date.now();
        const stream = new MediaStream([videoRecordingTrack]);
        const mimeType = videoRecorderMimeType();
        videoRecorder = new MediaRecorder(stream, mimeType ? { mimeType } : undefined);
        videoRecorder.ondataavailable = (event) => {
            if (event.data?.size > 0) videoRecordingChunks.push(event.data);
        };
        videoRecorder.onstop = () => {
            const blob = new Blob(videoRecordingChunks, { type: videoRecorder?.mimeType || 'video/webm' });
            const url = URL.createObjectURL(blob);
            const link = document.createElement('a');
            link.href = url;
            link.download = videoRecordingFileName(videoRecordingTrack);
            document.body.appendChild(link);
            link.click();
            link.remove();
            setTimeout(() => URL.revokeObjectURL(url), 30000);

            const seconds = ((Date.now() - videoRecordingStartedAt) / 1000).toFixed(1);
            appendChatLine('录制视频', `已保存 ${link.download}（${seconds}s，${(blob.size / 1024).toFixed(1)} KB）`, true);
            videoRecorder = null;
            videoRecordingChunks = [];
            videoRecordingTrack = null;
            updateVideoRecordButton();
        };
        videoRecorder.start(250);
        appendChatLine('录制视频', `开始录制 AI 视频：${describeTrack(videoRecordingTrack)}`, true);
        updateVideoRecordButton();
    }

    function stopVideoRecording() {
        if (videoRecorder?.state === 'recording') videoRecorder.stop();
    }

    function toggleVideoRecording() {
        if (videoRecorder?.state === 'recording') stopVideoRecording();
        else startVideoRecording();
    }

    function generatePcId() {
        const bytes = new Uint8Array(16);
        crypto.getRandomValues(bytes);
        return 'PC-' + Array.from(bytes).map((b) => b.toString(16).padStart(2, '0')).join('');
    }

    function isInternalPc(pc) {
        return Boolean(pc?.__aiNativeCopilotInternal);
    }

    function isUsableTrack(track) {
        return track && track.readyState === 'live' && !ignoredTrackIds.has(track.id);
    }

    function isLiveTrack(track) {
        return track && track.readyState === 'live';
    }

    function candidateFor(track, candidates) {
        let candidate = candidates.get(track.id);
        if (!candidate) {
            candidate = {
                track,
                receiver: null,
                reasons: new Set(),
                elements: new Set(),
                firstSeenAt: Date.now(),
                lastSeenAt: 0,
                lastPacketAt: 0,
                bytesReceived: 0,
                packetsReceived: 0,
                bytesDelta: 0,
                packetsDelta: 0,
                level: 0,
                score: 0,
                logged: false,
            };
            candidates.set(track.id, candidate);
        }
        candidate.track = track;
        candidate.lastSeenAt = Date.now();
        return candidate;
    }

    function businessSenderCandidateFor(sender, track, reason) {
        if (!sender) return null;
        const senderTrack = track || sender.track;
        if (senderTrack && senderTrack.kind !== 'audio') return null;

        const id = sender.__aiNativeCopilotBusinessSenderId || `business-sender-${businessSenderCandidates.size + 1}`;
        sender.__aiNativeCopilotBusinessSenderId = id;

        let candidate = businessSenderCandidates.get(id);
        if (!candidate) {
            candidate = {
                id,
                sender,
                track: senderTrack || null,
                originalTrack: senderTrack || null,
                sources: new Set(),
                bytesSent: 0,
                packetsSent: 0,
                bytesDelta: 0,
                packetsDelta: 0,
                score: 0,
                logged: false,
            };
            businessSenderCandidates.set(id, candidate);
        }

        candidate.sender = sender;
        candidate.track = senderTrack || sender.track || candidate.track;
        if (!isAiTakeover && senderTrack && senderTrack !== aiResponseAudioTrack) {
            candidate.originalTrack = senderTrack;
        }
        candidate.sources.add(reason);
        wrapBusinessSender(sender);
        return candidate;
    }

    function findReceiverForTrack(track) {
        if (!track) return null;
        return Array.from(window.__aiNativeCopilotReceivers || [])
            .find((receiver) => receiver.track === track) || null;
    }

    function rememberReceiver(receiver, reason) {
        if (!receiver?.track || isInternalPc(receiver.transport)) return;
        window.__aiNativeCopilotReceivers.add(receiver);
        const track = receiver.track;
        if (!isUsableTrack(track)) return;

        if (track.kind === 'audio') {
            const candidate = candidateFor(track, audioCandidates);
            candidate.receiver = receiver;
            candidate.reasons.add(reason);
        } else if (track.kind === 'video') {
            const candidate = candidateFor(track, videoCandidates);
            candidate.receiver = receiver;
            candidate.reasons.add(reason);
            chooseRemoteVideoTrack(reason);
        }
    }

    function setVuWidth(id, level) {
        const el = document.getElementById(id);
        if (!el) return;
        el.style.width = `${Math.min(100, level * 2500)}%`;
    }

    function renderVu() {
        inputVuLevel *= 0.88;
        aiOutVuLevel *= 0.88;
        setVuWidth('native-copilot-input-vu', inputVuLevel);
        setVuWidth('native-copilot-ai-vu', aiOutVuLevel);
        requestAnimationFrame(renderVu);
    }

    function levelFromStats(stat, memory) {
        let level = typeof stat.audioLevel === 'number' ? stat.audioLevel : 0;
        if (typeof stat.totalAudioEnergy === 'number' && typeof stat.totalSamplesDuration === 'number') {
            const prev = memory.get(stat.id);
            memory.set(stat.id, {
                energy: stat.totalAudioEnergy,
                duration: stat.totalSamplesDuration,
            });
            if (prev) {
                const energyDelta = stat.totalAudioEnergy - prev.energy;
                const durationDelta = stat.totalSamplesDuration - prev.duration;
                if (energyDelta > 0 && durationDelta > 0) {
                    level = Math.max(level, Math.sqrt(energyDelta / durationDelta));
                }
            }
        }
        return level;
    }

    async function refreshVuFromStats() {
        try {
            if (!(await checkLockedUserTracks('stats-before'))) return;
            await refreshAudioCandidateStats();
            chooseRemoteAudioTrack('stats');

            await refreshBusinessSenderStats();
            chooseBusinessAudioSender('stats');
            await checkLockedUserTracks('stats-after');
        } catch (error) {
            // Stats APIs are best-effort across browsers.
        }
    }

    async function refreshBusinessSenderStats() {
        for (const candidate of businessSenderCandidates.values()) {
            const sender = candidate.sender;
            if (!sender?.getStats) continue;
            candidate.track = sender.track || candidate.track;

            const report = await sender.getStats();
            report.forEach((stat) => {
                const kind = stat.kind || stat.mediaType;
                if (stat.type !== 'outbound-rtp' || kind !== 'audio') return;

                const key = `${candidate.id}:${stat.id}`;
                const prev = outboundStatsMemory.get(key);
                const bytes = typeof stat.bytesSent === 'number' ? stat.bytesSent : 0;
                const packets = typeof stat.packetsSent === 'number' ? stat.packetsSent : 0;
                candidate.bytesDelta = prev ? Math.max(0, bytes - prev.bytes) : 0;
                candidate.packetsDelta = prev ? Math.max(0, packets - prev.packets) : 0;
                candidate.bytesSent = bytes;
                candidate.packetsSent = packets;
                outboundStatsMemory.set(key, { bytes, packets });

                if (candidate.sender === businessAudioSender) {
                    businessOutboundStats.bytesDelta = candidate.bytesDelta;
                    businessOutboundStats.packetsDelta = candidate.packetsDelta;
                    businessOutboundStats.bytesSent = candidate.bytesSent;
                    businessOutboundStats.packetsSent = candidate.packetsSent;
                    aiOutVuLevel = Math.max(
                        aiOutVuLevel,
                        levelFromStats(stat, senderStatsMemory),
                        outputVuLevelFromStats()
                    );
                }
            });
        }
    }

    async function refreshAudioCandidateStats() {
        for (const candidate of audioCandidates.values()) {
            if (!isUsableTrack(candidate.track)) continue;
            const receiver = candidate.receiver || findReceiverForTrack(candidate.track);
            if (!receiver?.getStats) continue;
            candidate.receiver = receiver;

            const report = await receiver.getStats();
            report.forEach((stat) => {
                const kind = stat.kind || stat.mediaType;
                if (stat.type !== 'inbound-rtp' || kind !== 'audio') return;

                const prev = inboundStatsMemory.get(stat.id);
                const bytes = typeof stat.bytesReceived === 'number' ? stat.bytesReceived : 0;
                const packets = typeof stat.packetsReceived === 'number' ? stat.packetsReceived : 0;
                const bytesDelta = prev ? Math.max(0, bytes - prev.bytes) : 0;
                const packetsDelta = prev ? Math.max(0, packets - prev.packets) : 0;
                inboundStatsMemory.set(stat.id, { bytes, packets });

                candidate.bytesReceived = bytes;
                candidate.packetsReceived = packets;
                candidate.bytesDelta = bytesDelta;
                candidate.packetsDelta = packetsDelta;
                candidate.level = levelFromStats(stat, receiverStatsMemory);
                if (bytesDelta > 0 || packetsDelta > 0 || candidate.level > 0) {
                    candidate.lastPacketAt = Date.now();
                }

                if (candidate.track === remoteUserAudioTrack) {
                    inputVuLevel = Math.max(inputVuLevel, inputVuLevelFromCandidate(candidate));
                }
            });
        }
    }

    async function outboundAudioBytes(sender) {
        if (!sender?.getStats) return null;
        try {
            let total = 0;
            const report = await sender.getStats();
            report.forEach((stat) => {
                const kind = stat.kind || stat.mediaType;
                if (stat.type === 'outbound-rtp' && kind === 'audio' && typeof stat.bytesSent === 'number') {
                    total += stat.bytesSent;
                }
            });
            return total;
        } catch {
            return null;
        }
    }

    function aiReadyForMedia() {
        if (!aiPc || !aiPc.remoteDescription) return false;
        return (
            aiPc.connectionState === 'connected'
            || aiPc.iceConnectionState === 'connected'
            || aiPc.iceConnectionState === 'completed'
        );
    }

    function aiStateLabel() {
        if (!aiPc) return 'pc=null';
        return `conn=${aiPc.connectionState},ice=${aiPc.iceConnectionState},signaling=${aiPc.signalingState},remote=${aiPc.remoteDescription?.type || 'none'}`;
    }

    function waitForAiMediaReady(timeoutMs = 10000) {
        if (aiReadyForMedia()) return Promise.resolve(true);
        return new Promise((resolve) => {
            const startedAt = Date.now();
            const timer = setInterval(() => {
                if (aiReadyForMedia()) {
                    clearInterval(timer);
                    resolve(true);
                } else if (Date.now() - startedAt >= timeoutMs) {
                    clearInterval(timer);
                    resolve(false);
                }
            }, 250);
        });
    }

    function scheduleAiInputHealthCheck(track) {
        if (aiInputHealthTimer) clearTimeout(aiInputHealthTimer);
        aiInputHealthTimer = setTimeout(async () => {
            if (!aiAudioSender || aiAudioSender.track !== track) return;
            log(`checking native AI input after media connects: ${aiStateLabel()}`);
            const ready = await waitForAiMediaReady(10000);
            if (!ready || !aiAudioSender || aiAudioSender.track !== track) {
                log(`native AI input could not be verified: ${aiStateLabel()}`);
                return;
            }

            const before = await outboundAudioBytes(aiAudioSender);
            await new Promise((resolve) => setTimeout(resolve, 2500));
            if (!aiAudioSender || aiAudioSender.track !== track) return;
            const after = await outboundAudioBytes(aiAudioSender);
            log(`native AI input packet check: before=${before}, after=${after}, ${aiStateLabel()}`, true);
        }, 500);
    }

    function describeTrack(track) {
        if (!track) return 'none';
        return `${track.id}${track.muted ? ' muted' : ''}`;
    }

    function elementLayoutInfo(element) {
        if (!element?.getBoundingClientRect || !document.documentElement.contains(element)) return null;
        const rect = element.getBoundingClientRect();
        const viewportHeight = window.innerHeight || document.documentElement.clientHeight || 1;
        const centerY = rect.top + rect.height / 2;
        const visibleWidth = Math.max(0, Math.min(rect.right, window.innerWidth || document.documentElement.clientWidth || rect.right) - Math.max(rect.left, 0));
        const visibleHeight = Math.max(0, Math.min(rect.bottom, viewportHeight) - Math.max(rect.top, 0));
        return {
            tag: element.tagName,
            top: Math.round(rect.top),
            left: Math.round(rect.left),
            width: Math.round(rect.width),
            height: Math.round(rect.height),
            centerY: Math.round(centerY),
            upperHalf: centerY <= viewportHeight * 0.55,
            visibleArea: Math.round(visibleWidth * visibleHeight),
            paused: Boolean(element.paused),
            muted: Boolean(element.muted),
            volume: typeof element.volume === 'number' ? element.volume : null,
        };
    }

    function candidateLayoutScore(candidate) {
        let score = 0;
        for (const element of candidate?.elements || []) {
            const info = elementLayoutInfo(element);
            if (!info) continue;
            if (info.upperHalf) score += 9000;
            else score -= 2500;
            if (info.visibleArea > 0) score += Math.min(2500, info.visibleArea / 80);
            if (info.tag === 'VIDEO') score += 1200;
            if (info.tag === 'AUDIO') score += 300;
            if (!info.paused) score += 700;
            if (!info.muted && (info.volume ?? 1) > 0) score += 500;
        }
        return score;
    }

    function hasUpperHalfElement(candidate) {
        return Array.from(candidate?.elements || []).some((element) => elementLayoutInfo(element)?.upperHalf);
    }

    function lockedTrackUsable(track, candidates) {
        const candidate = candidates.get(track?.id);
        return Boolean(candidate && isUsableTrack(candidate.track) && !candidate.track.muted);
    }

    async function handleLockedUserTrackLost(kind, reason) {
        const message = `${kind === 'audio' ? '远端音频' : '远端视频'}轨道失效（${reason}），已断开 AI`;
        appendChatLine('选轨', message, true);
        log(message);
        if (kind === 'audio') {
            remoteUserAudioLocked = false;
            remoteUserAudioTrack = null;
        } else {
            remoteUserVideoLocked = false;
            remoteUserVideoTrack = null;
        }
        if (isAiTakeover) {
            isAiTakeover = false;
            updateModeButton();
            await restoreBusinessAudio();
            disconnectAi();
        }
    }

    async function checkLockedUserTracks(reason) {
        if (remoteUserAudioLocked && !lockedTrackUsable(remoteUserAudioTrack, audioCandidates)) {
            await handleLockedUserTrackLost('audio', reason);
            return false;
        }
        if (remoteUserVideoLocked && !lockedTrackUsable(remoteUserVideoTrack, videoCandidates)) {
            await handleLockedUserTrackLost('video', reason);
            return false;
        }
        return true;
    }

    function scoreAudioCandidate(candidate) {
        if (!candidate || !isUsableTrack(candidate.track)) return -1;
        const hasRecentPackets = Date.now() - candidate.lastPacketAt < 3000;
        const hasAudibleLevel = candidate.level >= 0.0015;
        let score = 0;
        if (candidate.track.muted) score -= 5000;
        else score += 800;
        score += candidateLayoutScore(candidate);
        if (candidate.receiver) score += 600;
        if (candidate.bytesReceived > 0) score += 100;
        if (candidate.bytesDelta > 0) score += 500 + Math.min(900, candidate.bytesDelta * 2);
        if (candidate.packetsDelta > 0) score += 300 + Math.min(500, candidate.packetsDelta * 8);
        if (hasRecentPackets) score += 400;
        if (hasAudibleLevel) score += 5000;
        score += Math.min(12000, candidate.level * 900000);
        if (!hasAudibleLevel && hasRecentPackets) score -= 1800;
        if (candidate.reasons.has('media-srcObject') || candidate.reasons.has('media-scan')) score += 80;
        return score;
    }

    function scoreVideoCandidate(candidate) {
        if (!candidate || !isUsableTrack(candidate.track)) return -1;
        let score = 0;
        if (candidate.track.muted) score -= 1000;
        else score += 500;
        if (candidate.receiver) score += 600;
        score += candidateLayoutScore(candidate);
        for (const element of candidate.elements || []) {
            const info = elementLayoutInfo(element);
            if (!info) continue;
            if (info.tag === 'VIDEO') score += 2500;
            if (info.visibleArea > 0) score += Math.min(4000, info.visibleArea / 50);
        }
        if (candidate.reasons.has('media-srcObject') || candidate.reasons.has('media-scan')) score += 100;
        return score;
    }

    function inputVuLevelFromCandidate(candidate) {
        if (!candidate) return 0;
        return Math.max(
            candidate.level,
            Math.min(0.04, candidate.bytesDelta / 16000),
            Math.min(0.02, candidate.packetsDelta / 800)
        );
    }

    function updateSelectedInputLabel() {
        const label = document.getElementById('native-copilot-selected-input');
        if (!label) return;
        const candidate = audioCandidates.get(remoteUserAudioTrack?.id);
        if (!candidate) {
            label.textContent = '等待远端音轨';
            return;
        }
        const layout = Array.from(candidate.elements || []).map(elementLayoutInfo).find(Boolean);
        const where = layout ? (layout.upperHalf ? 'upper' : 'lower') : 'no-layout';
        label.textContent = `${remoteUserAudioTrack.id.slice(0, 8)} ${where} level=${candidate.level.toFixed(4)} score=${Math.round(candidate.score || scoreAudioCandidate(candidate))}`;
    }

    function outputVuLevelFromStats() {
        return Math.max(
            Math.min(0.12, businessOutboundStats.bytesDelta / 12000),
            Math.min(0.04, businessOutboundStats.packetsDelta / 500)
        );
    }

    function isKnownRemoteAudioTrack(track) {
        return Boolean(track && (
            track === remoteUserAudioTrack
            || audioCandidates.has(track.id)
        ));
    }

    function isAiOutputTrack(track) {
        return Boolean(track && track === aiResponseAudioTrack);
    }

    function scoreBusinessSenderCandidate(candidate) {
        if (!candidate?.sender) return -1;
        const track = candidate.sender.track || candidate.track;
        let score = 0;

        if (track?.kind === 'audio') score += 500;
        else if (!track) score -= 1000;

        if (track?.readyState === 'live') score += 700;
        if (track && !track.muted) score += 300;
        if (candidate.sources.has('pc-addTrack')) score += 5000;
        if (candidate.sources.has('pc-addTransceiver')) score -= 1000;
        if (track && localCaptureTrackIds.has(track.id)) score += 2500;
        if (candidate.originalTrack && localCaptureTrackIds.has(candidate.originalTrack.id)) score += 2500;
        if (isKnownRemoteAudioTrack(track)) score -= 9000;
        if (candidate.originalTrack && isKnownRemoteAudioTrack(candidate.originalTrack)) score -= 9000;
        if (isAiOutputTrack(track)) score += 4500;
        if (candidate.bytesSent > 0) score += 600;
        if (candidate.bytesDelta > 0) score += 1600 + Math.min(1800, candidate.bytesDelta * 4);
        if (candidate.packetsDelta > 0) score += 800 + Math.min(900, candidate.packetsDelta * 10);

        return score;
    }

    function chooseBusinessAudioSender(reason) {
        let best = null;
        let bestScore = -1;
        for (const candidate of businessSenderCandidates.values()) {
            candidate.score = scoreBusinessSenderCandidate(candidate);
            if (candidate.score > bestScore) {
                best = candidate;
                bestScore = candidate.score;
            }
        }

        if (!best || bestScore < 0) return false;
        if (businessAudioSender === best.sender) return true;

        businessAudioSender = best.sender;
        businessOriginalAudioTrack = best.originalTrack || best.sender.track || businessOriginalAudioTrack;
        log(`selected business audio sender (${reason}): ${best.id}, track=${describeTrack(best.sender.track)}, score=${Math.round(bestScore)}, sources=${Array.from(best.sources).join('+')}`, true);
        attachAiOutputToBusiness();
        return true;
    }

    function chooseRemoteAudioTrack(reason) {
        const lockedAudio = audioCandidates.get(remoteUserAudioTrack?.id);
        if (remoteUserAudioLocked && lockedAudio && isUsableTrack(lockedAudio.track) && !lockedAudio.track.muted) {
            updateSelectedInputLabel();
            return true;
        }
        if (remoteUserAudioLocked) return false;

        let best = null;
        let bestScore = -1;
        for (const candidate of audioCandidates.values()) {
            candidate.score = scoreAudioCandidate(candidate);
            if (candidate.score > bestScore) {
                best = candidate;
                bestScore = candidate.score;
            }
        }

        if (!best || bestScore < 0) return false;
        if (remoteUserAudioTrack === best.track) {
            updateSelectedInputLabel();
            return true;
        }

        const current = audioCandidates.get(remoteUserAudioTrack?.id);
        const currentScore = scoreAudioCandidate(current);
        const currentHealthy = current && isUsableTrack(current.track) && !current.track.muted
            && (current.level >= 0.0015 || hasUpperHalfElement(current))
            && Date.now() - current.lastPacketAt < 3000;
        if (currentHealthy && bestScore < currentScore + 1800) {
            updateSelectedInputLabel();
            return true;
        }

        remoteUserAudioTrack = best.track;
        remoteUserAudioLocked = hasUpperHalfElement(best);
        log(`${remoteUserAudioLocked ? 'locked' : 'selected'} remote audio track (${reason}): ${describeTrack(best.track)}, score=${Math.round(bestScore)}, level=${best.level.toFixed(4)}, bytesDelta=${best.bytesDelta}, packetsDelta=${best.packetsDelta}`, true);
        updateSelectedInputLabel();
        attachRemoteInputToAi();
        return true;
    }

    function chooseRemoteVideoTrack(reason) {
        const lockedVideo = videoCandidates.get(remoteUserVideoTrack?.id);
        if (remoteUserVideoLocked && lockedVideo && isUsableTrack(lockedVideo.track) && !lockedVideo.track.muted) {
            return true;
        }
        if (remoteUserVideoLocked) return false;

        let best = null;
        let bestScore = -1;
        for (const candidate of videoCandidates.values()) {
            candidate.score = scoreVideoCandidate(candidate);
            if (candidate.score > bestScore) {
                best = candidate;
                bestScore = candidate.score;
            }
        }

        if (!best || bestScore < 0) return false;
        if (remoteUserVideoTrack === best.track) return true;

        const current = videoCandidates.get(remoteUserVideoTrack?.id);
        const currentScore = scoreVideoCandidate(current);
        if (hasUpperHalfElement(current) && bestScore < currentScore + 1800) return true;

        remoteUserVideoTrack = best.track;
        remoteUserVideoLocked = hasUpperHalfElement(best);
        log(`${remoteUserVideoLocked ? 'locked' : 'selected'} remote video track (${reason}): ${describeTrack(best.track)}, score=${Math.round(bestScore)}, layout=${Math.round(candidateLayoutScore(best))}`, true);
        attachRemoteVideoToAi();
        return true;
    }

    function ensureUserTracksBeforeConnect() {
        chooseRemoteAudioTrack('pre-connect');
        chooseRemoteVideoTrack('pre-connect');

        if (shouldSendAudioToAi() && (!remoteUserAudioLocked || !lockedTrackUsable(remoteUserAudioTrack, audioCandidates))) {
            appendChatLine('选轨', '未锁定上半部用户音频轨，暂不连接 AI', true);
            return false;
        }
        if (shouldSendVideoToAi() && (!remoteUserVideoLocked || !lockedTrackUsable(remoteUserVideoTrack, videoCandidates))) {
            appendChatLine('选轨', '未锁定上半部用户视频轨，暂不连接 AI', true);
            return false;
        }
        return true;
    }

    function rememberRemoteTrack(track, reason, element = null) {
        if (!isUsableTrack(track)) return;

        if (track.kind === 'audio') {
            const candidate = candidateFor(track, audioCandidates);
            candidate.receiver = candidate.receiver || findReceiverForTrack(track);
            candidate.reasons.add(reason);
            if (element) candidate.elements.add(element);
            if (!candidate.logged) {
                candidate.logged = true;
                log(`captured remote audio candidate (${reason}): ${describeTrack(track)}`, true);
            }
            chooseRemoteAudioTrack(reason);
            return;
        }

        if (track.kind === 'video') {
            const candidate = candidateFor(track, videoCandidates);
            candidate.receiver = candidate.receiver || findReceiverForTrack(track);
            candidate.reasons.add(reason);
            if (element) candidate.elements.add(element);
            if (!candidate.logged) {
                candidate.logged = true;
                log(`captured remote video candidate (${reason}): ${describeTrack(track)}`, true);
            }
            chooseRemoteVideoTrack(reason);
        }
    }

    function rememberRemoteStream(stream, reason, element = null) {
        if (!stream || !(stream instanceof MediaStream)) return;
        if (stream.__aiNativeCopilotInternal) return;

        const liveTracks = stream.getTracks().filter(isUsableTrack);
        if (liveTracks.length === 0) return;

        remoteStreams.add(stream);
        for (const track of liveTracks) rememberRemoteTrack(track, reason, element);
        chooseRemoteVideoTrack(reason);
    }

    function rememberBusinessAudioSender(sender, track, reason) {
        const candidate = businessSenderCandidateFor(sender, track, reason);
        if (!candidate) return;
        if (!candidate.logged) {
            candidate.logged = true;
            log(`captured business audio sender candidate (${reason}): ${candidate.id}, track=${describeTrack(candidate.track)}`, true);
        }
        chooseBusinessAudioSender(reason);
    }

    function wrapBusinessSender(sender) {
        if (!sender || sender.__aiNativeCopilotWrapped) return;
        const originalReplaceTrack = sender.replaceTrack?.bind(sender);
        if (!originalReplaceTrack) return;

        sender.replaceTrack = async function (track) {
            const result = await originalReplaceTrack(track);
            const candidate = businessSenderCandidateFor(sender, track, 'replaceTrack');
            if (candidate) {
                candidate.track = track || sender.track || candidate.track;
            }
            if (!isAiTakeover && track?.kind === 'audio' && track !== aiResponseAudioTrack) {
                if (candidate) candidate.originalTrack = track;
                chooseBusinessAudioSender('replaceTrack');
            }
            return result;
        };
        sender.__aiNativeCopilotWrapped = true;
    }

    async function attachRemoteInputToAi() {
        if (!shouldSendAudioToAi()) return false;
        if (!aiAudioSender || !isUsableTrack(remoteUserAudioTrack)) return false;
        if (aiAudioSender.track === remoteUserAudioTrack) return true;

        try {
            await aiAudioSender.replaceTrack(remoteUserAudioTrack);
            log(`AI input uses native remote audio track (${remoteUserAudioTrack.id})`, true);
            scheduleAiInputHealthCheck(remoteUserAudioTrack);
            return true;
        } catch (error) {
            log(`failed to attach native remote audio to AI: ${error.message || error}`);
            return false;
        }
    }

    async function attachRemoteVideoToAi() {
        if (!shouldSendVideoToAi()) return false;
        if (!aiVideoSender || !isUsableTrack(remoteUserVideoTrack)) return false;
        if (aiVideoSender.track === remoteUserVideoTrack) return true;

        try {
            await aiVideoSender.replaceTrack(remoteUserVideoTrack);
            log('AI video uses native remote video track', true);
            return true;
        } catch (error) {
            log(`failed to attach native remote video to AI: ${error.message || error}`);
            return false;
        }
    }

    async function attachAiOutputToBusiness() {
        chooseBusinessAudioSender('before-ai-output');
        if (!isAiTakeover || !businessAudioSender || !isLiveTrack(aiResponseAudioTrack)) {
            log(`AI output waiting: takeover=${isAiTakeover}, businessSender=${Boolean(businessAudioSender)}, aiTrack=${describeTrack(aiResponseAudioTrack)}`);
            return false;
        }
        if (businessAudioSender.track === aiResponseAudioTrack) return true;

        try {
            await businessAudioSender.replaceTrack(aiResponseAudioTrack);
            aiTrackAttachedToBusiness = true;
            log(`business call now uses native AI response audio track (${aiResponseAudioTrack.id})`, true);
            scheduleAiOutputHealthCheck(aiResponseAudioTrack);
            return true;
        } catch (error) {
            aiTrackAttachedToBusiness = false;
            log(`failed to attach AI audio to business call: ${error.message || error}`);
            return false;
        }
    }

    function scheduleAiOutputHealthCheck(track) {
        if (aiOutputHealthTimer) clearTimeout(aiOutputHealthTimer);
        aiOutputHealthTimer = setTimeout(async () => {
            if (!businessAudioSender || businessAudioSender.track !== track) {
                log(`AI output check skipped: senderTrack=${describeTrack(businessAudioSender?.track)}, aiTrack=${describeTrack(track)}`);
                return;
            }

            const before = await outboundAudioBytes(businessAudioSender);
            await new Promise((resolve) => setTimeout(resolve, 2500));
            if (!businessAudioSender || businessAudioSender.track !== track) return;
            const after = await outboundAudioBytes(businessAudioSender);
            log(`AI output packet check: before=${before}, after=${after}, senderTrack=${describeTrack(businessAudioSender.track)}`, true);
        }, 800);
    }

    async function restoreBusinessAudio() {
        if (!businessAudioSender || !aiTrackAttachedToBusiness) return;

        try {
            await businessAudioSender.replaceTrack(businessOriginalAudioTrack || null);
            log('business call restored original audio track', true);
        } catch (error) {
            log(`failed to restore business audio track: ${error.message || error}`);
        } finally {
            aiTrackAttachedToBusiness = false;
        }
    }

    function wrapTrackListener(listener) {
        if (!listener || listener.__aiNativeCopilotWrapped) return listener;

        const wrapped = function (event) {
            if (!isInternalPc(this) && event?.track) {
                rememberReceiver(event.receiver, 'pc-track');
                rememberRemoteTrack(event.track, 'pc-track');
                for (const stream of event.streams || []) rememberRemoteStream(stream, 'pc-track-stream');
            }

            if (typeof listener === 'function') return listener.apply(this, arguments);
            if (listener?.handleEvent) return listener.handleEvent(event);
            return undefined;
        };

        wrapped.__aiNativeCopilotWrapped = true;
        return wrapped;
    }

    RTCPeerConnection.prototype.addEventListener = function (type, listener, options) {
        if (type === 'track') {
            return originalAddEventListener.call(this, type, wrapTrackListener(listener), options);
        }
        return originalAddEventListener.call(this, type, listener, options);
    };

    try {
        const descriptor = Object.getOwnPropertyDescriptor(RTCPeerConnection.prototype, 'ontrack');
        Object.defineProperty(RTCPeerConnection.prototype, 'ontrack', {
            configurable: true,
            enumerable: true,
            get() {
                return descriptor?.get ? descriptor.get.call(this) : this.__aiNativeCopilotOnTrack || null;
            },
            set(listener) {
                const wrapped = wrapTrackListener(listener);
                this.__aiNativeCopilotOnTrack = wrapped;
                if (descriptor?.set) descriptor.set.call(this, wrapped);
                else this.addEventListener('track', wrapped);
            },
        });
    } catch (error) {
        console.warn('[AI Native Copilot] failed to wrap ontrack', error);
    }

    RTCPeerConnection.prototype.addTrack = function (track, ...streams) {
        const sender = originalAddTrack.call(this, track, ...streams);
        if (!isInternalPc(this) && track?.kind === 'audio') {
            rememberBusinessAudioSender(sender, track, 'pc-addTrack');
        }
        return sender;
    };

    if (originalAddTransceiver) {
        RTCPeerConnection.prototype.addTransceiver = function (trackOrKind, init) {
            const transceiver = originalAddTransceiver.call(this, trackOrKind, init);
            if (!isInternalPc(this)) {
                const kind = trackOrKind instanceof MediaStreamTrack ? trackOrKind.kind : trackOrKind;
                if (kind === 'audio') {
                    const track = trackOrKind instanceof MediaStreamTrack ? trackOrKind : transceiver.sender?.track;
                    rememberBusinessAudioSender(transceiver.sender, track, 'pc-addTransceiver');
                }
            }
            return transceiver;
        };
    }

    RTCPeerConnection.prototype.setRemoteDescription = function () {
        const result = originalSetRemoteDescription.apply(this, arguments);
        if (!isInternalPc(this)) {
            Promise.resolve(result).then(() => {
                try {
                    for (const receiver of this.getReceivers?.() || []) {
                        rememberReceiver(receiver, 'receiver-after-srd');
                        rememberRemoteTrack(receiver.track, 'receiver-after-srd');
                    }
                    for (const sender of this.getSenders?.() || []) {
                        rememberBusinessAudioSender(sender, sender.track, 'sender-after-srd');
                    }
                    for (const stream of this.getRemoteStreams?.() || []) {
                        rememberRemoteStream(stream, 'remote-stream-after-srd');
                    }
                } catch (error) {
                    console.warn('[AI Native Copilot] failed to scan receivers', error);
                }
            });
        }
        return result;
    };

    if (mediaSrcObjectDescriptor?.set) {
        Object.defineProperty(HTMLMediaElement.prototype, 'srcObject', {
            configurable: true,
            enumerable: mediaSrcObjectDescriptor.enumerable,
            get() {
                return mediaSrcObjectDescriptor.get.call(this);
            },
            set(stream) {
                if ((this.tagName === 'AUDIO' || this.tagName === 'VIDEO') && !this.__aiNativeCopilotElement) {
                    rememberRemoteStream(stream, 'media-srcObject', this);
                }
                return mediaSrcObjectDescriptor.set.call(this, stream);
            },
        });
    }

    if (originalGetUserMedia) {
        navigator.mediaDevices.getUserMedia = async function (constraints) {
            const stream = await originalGetUserMedia(constraints);
            for (const track of stream.getAudioTracks()) {
                localCaptureTrackIds.add(track.id);
            }
            chooseBusinessAudioSender('getUserMedia');
            renderPanelSoon();
            return stream;
        };
    }

    setInterval(async () => {
        if (!(await checkLockedUserTracks('scan'))) return;
        for (const element of document.querySelectorAll('audio, video')) {
            if (element.__aiNativeCopilotElement) continue;
            rememberRemoteStream(element.srcObject, 'media-scan', element);
        }

        for (const stream of Array.from(remoteStreams)) {
            rememberRemoteStream(stream, 'stream-rescan');
        }
        await checkLockedUserTracks('scan-after');
    }, 1000);

    window.__aiNativeCopilotDump = function () {
        const audio = Array.from(audioCandidates.values()).map((candidate) => ({
            id: candidate.track.id,
            label: candidate.track.label,
            selected: candidate.track === remoteUserAudioTrack,
            enabled: candidate.track.enabled,
            muted: candidate.track.muted,
            readyState: candidate.track.readyState,
            hasReceiver: Boolean(candidate.receiver || findReceiverForTrack(candidate.track)),
            bytesReceived: candidate.bytesReceived,
            packetsReceived: candidate.packetsReceived,
            bytesDelta: candidate.bytesDelta,
            packetsDelta: candidate.packetsDelta,
            level: candidate.level,
            audible: candidate.level >= 0.0015,
            layoutScore: Math.round(candidateLayoutScore(candidate)),
            elements: Array.from(candidate.elements || []).map(elementLayoutInfo).filter(Boolean),
            vuLevel: inputVuLevelFromCandidate(candidate),
            score: Math.round(scoreAudioCandidate(candidate)),
            reasons: Array.from(candidate.reasons),
        }));
        const video = Array.from(videoCandidates.values()).map((candidate) => ({
            id: candidate.track.id,
            label: candidate.track.label,
            selected: candidate.track === remoteUserVideoTrack,
            muted: candidate.track.muted,
            readyState: candidate.track.readyState,
            hasReceiver: Boolean(candidate.receiver || findReceiverForTrack(candidate.track)),
            layoutScore: Math.round(candidateLayoutScore(candidate)),
            score: Math.round(scoreVideoCandidate(candidate)),
            elements: Array.from(candidate.elements || []).map(elementLayoutInfo).filter(Boolean),
            reasons: Array.from(candidate.reasons),
        }));
        const businessSenders = Array.from(businessSenderCandidates.values()).map((candidate) => ({
            id: candidate.id,
            selected: candidate.sender === businessAudioSender,
            track: describeTrack(candidate.sender.track || candidate.track),
            originalTrack: describeTrack(candidate.originalTrack),
            isRemoteTrack: isKnownRemoteAudioTrack(candidate.sender.track || candidate.track),
            isLocalCaptureTrack: Boolean(candidate.sender.track && localCaptureTrackIds.has(candidate.sender.track.id)),
            bytesSent: candidate.bytesSent,
            packetsSent: candidate.packetsSent,
            bytesDelta: candidate.bytesDelta,
            packetsDelta: candidate.packetsDelta,
            score: Math.round(scoreBusinessSenderCandidate(candidate)),
            sources: Array.from(candidate.sources),
        }));
        return {
            selectedAudio: describeTrack(remoteUserAudioTrack),
            selectedVideo: describeTrack(remoteUserVideoTrack),
            audioLocked: remoteUserAudioLocked,
            videoLocked: remoteUserVideoLocked,
            aiInputTrack: describeTrack(aiAudioSender?.track),
            aiOutputTrack: describeTrack(aiResponseAudioTrack),
            businessSenderTrack: describeTrack(businessAudioSender?.track),
            aiTrackAttachedToBusiness,
            videoRecording: videoRecorder?.state === 'recording' ? {
                track: describeTrack(videoRecordingTrack),
                seconds: ((Date.now() - videoRecordingStartedAt) / 1000).toFixed(1),
                chunks: videoRecordingChunks.length,
            } : null,
            businessOutboundStats: { ...businessOutboundStats },
            aiState: aiStateLabel(),
            audio,
            video,
            businessSenders,
        };
    };

    async function connectAi(signalingUrl, assistantId) {
        if (!ensureUserTracksBeforeConnect()) {
            setStatus('disconnected');
            return false;
        }
        disconnectAi();

        const pcId = generatePcId();
        aiPc = new RTCPeerConnection({ iceServers: [{ urls: 'stun:stun.l.google.com:19302' }] });
        aiPc.__aiNativeCopilotInternal = true;
        aiPc.onconnectionstatechange = () => log(`AI PC connectionState=${aiPc.connectionState}`);
        aiPc.oniceconnectionstatechange = () => log(`AI PC iceConnectionState=${aiPc.iceConnectionState}`);

        aiDc = aiPc.createDataChannel('chat');
        aiDc.onopen = () => {
            setStatus('connected');
            log('AI data channel open', true);
            aiDc.send(JSON.stringify({ type: 'client-ready' }));
        };
        aiDc.onclose = () => setStatus('disconnected');
        aiDc.onmessage = (event) => {
            try {
                const msg = JSON.parse(event.data);
                const content = msg.delta || msg.content;
                if (msg.type === 'transcript') {
                    logUserTranscript(content);
                } else if (msg.type === 'assistant-text-start') {
                    startAssistantLine();
                } else if (msg.type === 'assistant-text-delta') {
                    appendAssistantDelta(content);
                } else if (msg.type === 'assistant-text-end') {
                    finishAssistantLine();
                } else {
                    log(`data channel message: ${msg.type}`);
                }
            } catch {
                appendChatLine('DATA', event.data);
            }
        };

        const sendAudio = shouldSendAudioToAi();
        const audioTransceiver = sendAudio && isUsableTrack(remoteUserAudioTrack)
            ? aiPc.addTransceiver(remoteUserAudioTrack, { direction: 'sendrecv' })
            : aiPc.addTransceiver('audio', { direction: sendAudio ? 'sendrecv' : 'recvonly' });
        aiAudioSender = audioTransceiver.sender;
        log(!sendAudio
            ? 'AI audio uplink disabled by panel setting'
            : isUsableTrack(remoteUserAudioTrack)
            ? 'AI input starts with native remote audio track'
            : 'AI input waiting for native remote audio track', true);

        const sendVideo = shouldSendVideoToAi();
        if (sendVideo) {
            const videoTransceiver = isUsableTrack(remoteUserVideoTrack)
                ? aiPc.addTransceiver(remoteUserVideoTrack, { direction: 'sendonly' })
                : aiPc.addTransceiver('video', { direction: 'sendonly' });
            aiVideoSender = videoTransceiver.sender;
            if (isUsableTrack(remoteUserVideoTrack)) log('AI video starts with native remote video track', true);
        } else {
            aiVideoSender = null;
            log('AI video uplink disabled by panel setting');
        }
        if (sendAudio && isUsableTrack(remoteUserAudioTrack)) scheduleAiInputHealthCheck(remoteUserAudioTrack);

        aiPc.ontrack = (event) => {
            if (event.track.kind !== 'audio') return;
            ignoredTrackIds.add(event.track.id);
            aiResponseAudioTrack = event.track;
            log('received native AI response audio track', true);
            attachAiOutputToBusiness();
        };

        aiPc.onicecandidate = (event) => {
            if (aiWs?.readyState !== WebSocket.OPEN) return;
            aiWs.send(JSON.stringify({
                type: 'ice-candidate',
                payload: {
                    pc_id: pcId,
                    candidate: event.candidate ? {
                        candidate: event.candidate.candidate,
                        sdpMid: event.candidate.sdpMid,
                        sdpMLineIndex: event.candidate.sdpMLineIndex,
                    } : null,
                },
            }));
        };

        setStatus('connecting');
        aiWs = new WebSocket(signalingUrl);
        aiWs.onopen = async () => {
            const offer = await aiPc.createOffer();
            await aiPc.setLocalDescription(offer);
            aiWs.send(JSON.stringify({
                type: 'offer',
                payload: {
                    pc_id: pcId,
                    sdp: aiPc.localDescription.sdp,
                    type: aiPc.localDescription.type,
                    assistant_id: assistantId,
                    vision_enabled: sendVideo,
                },
            }));
            log('sent AI WebRTC offer', true);
        };
        aiWs.onmessage = async (event) => {
            try {
                const msg = JSON.parse(event.data);
                if (msg.type === 'answer') {
                    await aiPc.setRemoteDescription({ type: 'answer', sdp: msg.payload.sdp });
                    log(`AI WebRTC answer applied; ${aiStateLabel()}`, true);
                } else if (msg.type === 'ice-candidate' && msg.payload?.candidate) {
                    await aiPc.addIceCandidate(msg.payload.candidate).catch(() => {});
                } else if (msg.type === 'error') {
                    throw new Error(msg.payload?.message || 'server error');
                }
            } catch (error) {
                log(`signaling error: ${error.message || error}`);
            }
        };
        aiWs.onerror = () => {
            setStatus('failed');
            log('AI signaling websocket error');
        };
        aiWs.onclose = () => setStatus('disconnected');

        attachRemoteInputToAi();
        if (sendVideo) attachRemoteVideoToAi();
        return true;
    }

    function disconnectAi() {
        if (aiDc) {
            try { aiDc.close(); } catch {}
            aiDc = null;
        }
        if (aiPc) {
            try { aiPc.close(); } catch {}
            aiPc = null;
        }
        if (aiWs) {
            try { aiWs.close(); } catch {}
            aiWs = null;
        }
        aiAudioSender = null;
        aiVideoSender = null;
        aiResponseAudioTrack = null;
        if (inputRecorder?.state === 'recording') stopInputRecording();
        if (videoRecorder?.state === 'recording') stopVideoRecording();
        setStatus('disconnected');
    }

    function setStatus(status) {
        const el = document.getElementById('native-copilot-status');
        if (!el) return;
        const labels = {
            disconnected: '未连接',
            connecting: '连接中',
            connected: '已连接',
            failed: '连接失败',
        };
        el.textContent = labels[status] || status;
    }

    function updateModeButton() {
        const button = document.getElementById('native-copilot-toggle');
        if (!button) return;
        if (isAiTakeover) {
            button.textContent = '当前：AI 接管｜点击切回人工';
            button.style.background = '#8b5cf6';
        } else {
            button.textContent = '当前：人工接管｜点击切换 AI';
            button.style.background = '#10b981';
        }
    }

    function renderPanel() {
        if (!document.body || document.getElementById('native-copilot-panel')) return;

        const panel = document.createElement('div');
        panel.id = 'native-copilot-panel';
        panel.style.cssText = [
            'position:fixed',
            'top:20px',
            'left:20px',
            'width:360px',
            'z-index:999999',
            'box-sizing:border-box',
            'padding:16px',
            'border-radius:10px',
            'background:rgba(17,24,39,.96)',
            'color:white',
            'font-family:system-ui,-apple-system,BlinkMacSystemFont,sans-serif',
            'box-shadow:0 12px 32px rgba(0,0,0,.35)',
        ].join(';');

        panel.innerHTML = `
            <div style="display:flex;justify-content:space-between;gap:12px;align-items:center;margin-bottom:12px;">
                <strong style="font-size:15px;color:#93c5fd;">AI 原生选轨</strong>
                <span id="native-copilot-status" style="font-size:12px;color:#d1d5db;">未连接</span>
            </div>
            <div style="font-size:11px;color:#9ca3af;margin-bottom:10px;line-height:1.5;">
                音频输入：布局优先自动选轨<br>
                视频输入：远端视频轨
            </div>
            <label style="display:block;font-size:12px;color:#9ca3af;margin-bottom:4px;">信令地址</label>
            <input id="native-copilot-url" value="${DEFAULT_SIGNALING_URL}" style="width:100%;box-sizing:border-box;margin-bottom:10px;padding:8px;border:1px solid #4b5563;border-radius:6px;background:#111827;color:white;">
            <label style="display:block;font-size:12px;color:#9ca3af;margin-bottom:4px;">助手 ID</label>
            <input id="native-copilot-assistant" placeholder="请输入助手 ID" style="width:100%;box-sizing:border-box;margin-bottom:12px;padding:8px;border:1px solid #4b5563;border-radius:6px;background:#111827;color:white;">
            <div style="display:grid;grid-template-columns:1fr 1fr;gap:8px;margin-bottom:12px;">
                <label style="display:flex;align-items:center;gap:6px;padding:8px;border:1px solid #374151;border-radius:6px;background:#111827;font-size:12px;color:#e5e7eb;cursor:pointer;">
                    <input id="native-copilot-send-audio" type="checkbox" style="margin:0;">
                    <span>传音频给 AI</span>
                </label>
                <label style="display:flex;align-items:center;gap:6px;padding:8px;border:1px solid #374151;border-radius:6px;background:#111827;font-size:12px;color:#e5e7eb;cursor:pointer;">
                    <input id="native-copilot-send-video" type="checkbox" style="margin:0;">
                    <span>传视频给 AI</span>
                </label>
            </div>
            <div style="margin-bottom:10px;">
                <div style="display:flex;justify-content:space-between;gap:8px;font-size:12px;color:#d1fae5;margin-bottom:4px;">
                    <span id="native-copilot-selected-input" style="overflow:hidden;text-overflow:ellipsis;white-space:nowrap;">等待远端音轨</span><span>原生音轨</span>
                </div>
                <div style="height:8px;border-radius:999px;overflow:hidden;background:#374151;">
                    <div id="native-copilot-input-vu" style="height:100%;width:0%;background:linear-gradient(90deg,#10b981,#fcd34d);transition:width .06s linear;"></div>
                </div>
            </div>
            <div style="margin-bottom:12px;">
                <div style="display:flex;justify-content:space-between;font-size:12px;color:#bfdbfe;margin-bottom:4px;">
                    <span>AI 输出</span><span>业务上行</span>
                </div>
                <div style="height:8px;border-radius:999px;overflow:hidden;background:#374151;">
                    <div id="native-copilot-ai-vu" style="height:100%;width:0%;background:linear-gradient(90deg,#60a5fa,#c084fc);transition:width .06s linear;"></div>
                </div>
            </div>
            <button id="native-copilot-toggle" style="width:100%;padding:12px;border:0;border-radius:6px;background:#10b981;color:white;font-weight:700;cursor:pointer;">当前：人工接管｜点击切换 AI</button>
            <div style="display:grid;grid-template-columns:1fr 1fr;gap:8px;margin-top:8px;">
                <button id="native-copilot-record" style="width:100%;padding:10px;border:0;border-radius:6px;background:#2563eb;color:white;font-weight:700;cursor:pointer;">录制 AI 输入</button>
                <button id="native-copilot-record-video" style="width:100%;padding:10px;border:0;border-radius:6px;background:#475569;color:white;font-weight:700;cursor:pointer;">录制 AI 视频</button>
            </div>
            <div id="native-copilot-log" style="height:170px;margin-top:12px;padding:8px;overflow:auto;border:1px solid #374151;border-radius:6px;background:#030712;color:#a7f3d0;font:11px ui-monospace,Menlo,monospace;">
                <span data-placeholder="1" style="color:#6b7280;">等待交互...</span>
            </div>
        `;

        document.body.appendChild(panel);

        const toggle = document.getElementById('native-copilot-toggle');
        const recordButton = document.getElementById('native-copilot-record');
        const videoRecordButton = document.getElementById('native-copilot-record-video');
        const urlInput = document.getElementById('native-copilot-url');
        const assistantInput = document.getElementById('native-copilot-assistant');
        const sendAudioInput = document.getElementById('native-copilot-send-audio');
        const sendVideoInput = document.getElementById('native-copilot-send-video');

        sendAudioInput.checked = shouldSendAudioToAi();
        sendVideoInput.checked = shouldSendVideoToAi();
        sendAudioInput.addEventListener('change', () => {
            writeBoolSetting(AUDIO_UPLINK_STORAGE_KEY, sendAudioInput.checked);
            log(`AI audio uplink setting: ${sendAudioInput.checked ? 'on' : 'off'}`);
        });
        sendVideoInput.addEventListener('change', () => {
            writeBoolSetting(VIDEO_UPLINK_STORAGE_KEY, sendVideoInput.checked);
            log(`AI video uplink setting: ${sendVideoInput.checked ? 'on' : 'off'}`);
        });
        recordButton.addEventListener('click', toggleInputRecording);
        videoRecordButton.addEventListener('click', toggleVideoRecording);
        updateRecordButton();
        updateVideoRecordButton();
        updateSelectedInputLabel();
        updateModeButton();

        toggle.addEventListener('click', async () => {
            if (!isAiTakeover && !assistantInput.value.trim()) {
                alert('请先填写助手 ID。');
                return;
            }

            if (!isAiTakeover && !ensureUserTracksBeforeConnect()) {
                updateModeButton();
                return;
            }

            isAiTakeover = !isAiTakeover;
            updateModeButton();
            if (isAiTakeover) {
                const connected = await connectAi(urlInput.value.trim(), assistantInput.value.trim());
                if (connected) await attachAiOutputToBusiness();
                else {
                    isAiTakeover = false;
                    updateModeButton();
                }
            } else {
                await restoreBusinessAudio();
                disconnectAi();
            }
        });
    }

    function renderPanelSoon() {
        try { renderPanel(); } catch (error) { console.warn('[AI Native Copilot] panel error', error); }
    }

    if (document.readyState === 'loading') {
        document.addEventListener('DOMContentLoaded', renderPanelSoon, { once: true });
    } else {
        renderPanelSoon();
    }
    requestAnimationFrame(renderVu);
    setInterval(refreshVuFromStats, 250);
    setTimeout(renderPanelSoon, 1500);
    setTimeout(renderPanelSoon, 3000);
})();