> ## Documentation Index > Fetch the complete documentation index at: https://langchain-zh.cn/llms.txt > Use this file to discover all available pages before exploring further. # 图执行 > 可视化多步骤图流水线，展示每个节点的状态和流式内容 export const PatternEmbed = ({pattern, theme, height, minHeight = 400, maxHeight = 700, className, defaultView = "preview", defaultSdk = "react", defaultLanguage = "js", showCodeTab = true, agentServer = "prod", onError, onReady}) => { var VALID_GUEST_TYPES = new Set(["READY", "RESIZE", "ERROR", "RUN_STARTED", "TRACE_URL", "THREAD_CLEARED"]); function stub() { return { safeParse: data => ({ success: true, data }), optional: () => stub(), min: () => stub(), url: () => stub() }; } var z = { object: _shape => stub(), literal: _value => stub(), string: () => stub(), number: () => stub(), boolean: () => stub(), enum: _values => stub(), array: _el => stub(), union: _schemas => stub(), record: (_key, _value) => stub(), discriminatedUnion: (_key, _schemas) => ({ safeParse(data) { if (data != null && typeof data === "object" && ("type" in data) && typeof data.type === "string" && VALID_GUEST_TYPES.has(data.type)) { return { success: true, data }; } return { success: false }; }, optional: () => stub(), min: () => stub(), url: () => stub() }) }; var SetThemeMessageSchema = z.object({ type: z.literal("SET_THEME"), theme: z.enum(["light", "dark"]) }); var SetPatternMessageSchema = z.object({ type: z.literal("SET_PATTERN"), slug: z.string() }); var ResetMessageSchema = z.object({ type: z.literal("RESET") }); var SetViewMessageSchema = z.object({ type: z.literal("SET_VIEW"), view: z.enum(["preview", "code"]) }); var SetLanguageMessageSchema = z.object({ type: z.literal("SET_LANGUAGE"), language: z.enum(["js", "python"]) }); var CodeFileSchema = z.object({ filename: z.string(), content: z.string() }); var UpdateCodeMessageSchema = z.object({ type: z.literal("UPDATE_CODE"), files: z.array(CodeFileSchema).min(1), entryFile: z.string() }); var TrackEventMessageSchema = z.object({ type: z.literal("TRACK_EVENT"), name: z.string(), properties: z.record(z.string(), z.union([z.string(), z.number(), z.boolean()])).optional() }); var HostToGuestMessageSchema = z.discriminatedUnion("type", [SetThemeMessageSchema, SetPatternMessageSchema, ResetMessageSchema, UpdateCodeMessageSchema, SetViewMessageSchema, SetLanguageMessageSchema, TrackEventMessageSchema]); var ReadyMessageSchema = z.object({ type: z.literal("READY"), framework: z.enum(["react", "vue", "angular", "svelte"]) }); var ResizeMessageSchema = z.object({ type: z.literal("RESIZE"), height: z.number() }); var ErrorMessageSchema = z.object({ type: z.literal("ERROR"), message: z.string(), stack: z.string().optional() }); var RunStartedMessageSchema = z.object({ type: z.literal("RUN_STARTED"), runId: z.string() }); var TraceUrlMessageSchema = z.object({ type: z.literal("TRACE_URL"), url: z.string().url(), runId: z.string() }); var ThreadClearedMessageSchema = z.object({ type: z.literal("THREAD_CLEARED") }); var GuestToHostMessageSchema = z.discriminatedUnion("type", [ReadyMessageSchema, ResizeMessageSchema, ErrorMessageSchema, RunStartedMessageSchema, TraceUrlMessageSchema, ThreadClearedMessageSchema]); var PreviewMessageSchema = z.union([HostToGuestMessageSchema, GuestToHostMessageSchema]); function isOriginAllowed(origin, allowedOrigins) { return allowedOrigins.includes("*") || allowedOrigins.includes(origin); } function createPreviewHost(iframe, options) { const {allowedOrigins} = options; const targetOrigins = options.targetOrigins ?? allowedOrigins; const listeners = new Map(); function postToGuest(message) { if (!iframe.contentWindow) return; for (const origin of targetOrigins) { iframe.contentWindow.postMessage(message, origin); } } function addListener(type, callback) { if (!listeners.has(type)) { listeners.set(type, new Set()); } listeners.get(type).add(callback); return () => { listeners.get(type)?.delete(callback); }; } function handleMessage(event) { if (!isOriginAllowed(event.origin, allowedOrigins)) return; const result = GuestToHostMessageSchema.safeParse(event.data); if (!result.success) return; const msg = result.data; const cbs = listeners.get(msg.type); if (!cbs) return; for (const cb of cbs) { switch (msg.type) { case "READY": cb(msg.framework); break; case "RESIZE": cb(msg.height); break; case "ERROR": cb(msg.message, msg.stack); break; case "RUN_STARTED": cb(msg.runId); break; case "TRACE_URL": cb(msg.url, msg.runId); break; case "THREAD_CLEARED": cb(); break; } } } window.addEventListener("message", handleMessage); return { setTheme(theme) { postToGuest({ type: "SET_THEME", theme }); }, setPattern(slug) { postToGuest({ type: "SET_PATTERN", slug }); }, setView(view) { postToGuest({ type: "SET_VIEW", view }); }, setLanguage(language) { postToGuest({ type: "SET_LANGUAGE", language }); }, updateCode(files, entryFile) { postToGuest({ type: "UPDATE_CODE", files, entryFile }); }, reset() { postToGuest({ type: "RESET" }); }, trackEvent(name, properties) { postToGuest({ type: "TRACK_EVENT", name, properties }); }, onReady(callback) { return addListener("READY", callback); }, onResize(callback) { return addListener("RESIZE", callback); }, onError(callback) { return addListener("ERROR", callback); }, onRunStarted(callback) { return addListener("RUN_STARTED", callback); }, onTraceUrl(callback) { return addListener("TRACE_URL", callback); }, onThreadCleared(callback) { return addListener("THREAD_CLEARED", callback); }, destroy() { window.removeEventListener("message", handleMessage); listeners.clear(); } }; } var PROD_BASE = "https://ui-patterns.langchain.com"; var SDK_LABELS = { react: "React", vue: "Vue", svelte: "Svelte", angular: "Angular" }; var SDK_LOCAL_HOSTS = { react: "http://localhost:4100", vue: "http://localhost:4200", svelte: "http://localhost:4300", angular: "http://localhost:4400" }; var SDK_PROD_HOSTS = { react: `${PROD_BASE}/react`, vue: `${PROD_BASE}/vue`, svelte: `${PROD_BASE}/svelte`, angular: `${PROD_BASE}/angular` }; var SDK_LOGOS = { react: ``, vue: ``, svelte: ``, angular: `` }; var PROD_AGENT_API_BASE = `${PROD_BASE}/api/langgraph`; function normalizeAgentServerBase(agentServer, useLocalPreview) { const trimmed = agentServer.trim(); if (useLocalPreview) { return "http://localhost:2024"; } if (trimmed === "prod") { return PROD_AGENT_API_BASE; } if (trimmed === "local") { return PROD_AGENT_API_BASE; } return PROD_AGENT_API_BASE; } function isLocalhost() { if (typeof window === "undefined") return false; const {hostname} = window.location; return hostname === "localhost" || hostname === "127.0.0.1" || hostname === "[::]"; } function detectPageTheme() { if (typeof document === "undefined") return "light"; const el = document.documentElement; if (el.classList.contains("dark")) return "dark"; if (el.getAttribute("data-theme") === "dark") return "dark"; if (el.style.colorScheme === "dark") return "dark"; return "light"; } var CACHE_KEY = "__lcPlaygroundIframeCache"; var iframeCache = globalThis[CACHE_KEY] ?? (() => { const m = new Map(); globalThis[CACHE_KEY] = m; return m; })(); var SDK_CACHE_KEY = "__lcPlaygroundSdkCache"; var sdkCache = globalThis[SDK_CACHE_KEY] ?? (() => { const m = new Map(); globalThis[SDK_CACHE_KEY] = m; return m; })(); var LANG_CACHE_KEY = "__lcPlaygroundLangCache"; var langCache = globalThis[LANG_CACHE_KEY] ?? (() => { const m = new Map(); globalThis[LANG_CACHE_KEY] = m; return m; })(); var VIEW_EYE_SVG = ``; var VIEW_CODE_SVG = ``; var CHEVRON_DOWN_SVG = ``; var TRACE_ICON_SVG = ``; var TRACE_SPINNER_SVG = ``; var EXTERNAL_LINK_SVG = ``; var DOWNLOAD_SVG = ``; var EXPAND_SVG = ``; var CLOSE_SVG = ``; var LANG_TS_SVG = ``; var LANG_PYTHON_SVG = ` `; var SDK_OPTIONS = Object.keys(SDK_LABELS).map(k => [k, SDK_LABELS[k]]); var EMBED_CSS = ` [data-lc-pe] .lc-tab{font-size:13px;font-family:inherit} [data-lc-pe] .lc-sdk-option{font-size:13px} [data-lc-pe] .lc-border{border-color:#B8DFFF} [data-lc-pe].dark .lc-border{border-color:#1A2740} [data-lc-pe] .lc-bg-surface{background-color:white} [data-lc-pe].dark .lc-bg-surface{background-color:#0B1120} [data-lc-pe] .lc-bg-wash{background-color:#F2FAFF} [data-lc-pe].dark .lc-bg-wash{background-color:#030710} [data-lc-pe] .lc-tab-active{background-color:#7FC8FF;color:#030710} [data-lc-pe] .lc-tab-inactive{background-color:transparent;color:#6B8299} [data-lc-pe] .lc-tab-inactive:hover{background-color:#E5F4FF;color:#030710} [data-lc-pe].dark .lc-tab-inactive:hover{background-color:#1A2740;color:#C8DDF0} [data-lc-pe] .lc-tab-trace{background-color:#FFF3E0;color:#E65100} [data-lc-pe].dark .lc-tab-trace{background-color:#3E2723;color:#FFB74D} [data-lc-pe] .lc-tab-trace:hover{background-color:#FFE0B2} [data-lc-pe].dark .lc-tab-trace:hover{background-color:#4E342E} [data-lc-pe] .lc-tab-trace-loading{background-color:transparent;color:#6B8299;cursor:not-allowed} [data-lc-pe] .lc-sdk-btn{border-color:#B8DFFF;background-color:white;font-size:13px;color:#030710} [data-lc-pe].dark .lc-sdk-btn{border-color:#1A2740;background-color:#0B1120;color:#C8DDF0} [data-lc-pe] .lc-sdk-btn:hover{background-color:#E5F4FF} [data-lc-pe].dark .lc-sdk-btn:hover{background-color:#1A2740} [data-lc-pe] .lc-dropdown{border-color:#B8DFFF;background-color:white;min-width:120px} [data-lc-pe].dark .lc-dropdown{border-color:#1A2740;background-color:#0B1120} [data-lc-pe] .lc-sdk-selected{background-color:#E5F4FF;color:#030710} [data-lc-pe].dark .lc-sdk-selected{background-color:#1A2740;color:#C8DDF0} [data-lc-pe] .lc-sdk-unselected{color:#6B8299} [data-lc-pe] .lc-sdk-unselected:hover{background-color:#F2FAFF;color:#030710} [data-lc-pe].dark .lc-sdk-unselected:hover{background-color:#1A2740;color:#C8DDF0} [data-lc-pe] .lc-spinner{border-color:#B8DFFF;border-top-color:#7FC8FF} [data-lc-pe].dark .lc-spinner{border-color:#1A2740;border-top-color:#7FC8FF} [data-lc-pe] .lc-error{background-color:rgb(178 125 117/0.1);border-color:rgb(178 125 117/0.3);color:#B27D75} [data-lc-pe] .lc-error-btn{border-color:rgb(178 125 117/0.3);background-color:white;color:#B27D75} [data-lc-pe].dark .lc-error-btn{background-color:#0B1120} [data-lc-pe] .lc-lang-switcher .lc-tab{padding:4px 8px} @media(max-width:639px){ [data-lc-pe] .lc-toolbar{flex-wrap:wrap;gap:8px} [data-lc-pe] .lc-tab-label{display:none} [data-lc-pe] .lc-tab{padding-left:10px;padding-right:10px} [data-lc-pe] .lc-sdk-btn{margin-left:auto} } [data-lc-pe] .lc-expand-btn{border:none;background:transparent;cursor:pointer;padding:6px;border-radius:6px;display:inline-flex;align-items:center;justify-content:center;color:#6B8299;transition:background-color 0.15s,color 0.15s} [data-lc-pe] .lc-expand-btn:hover{background-color:#E5F4FF;color:#030710} [data-lc-pe].dark .lc-expand-btn:hover{background-color:#1A2740;color:#C8DDF0} .lc-pe-backdrop{position:fixed;inset:0;z-index:9998;background:rgba(0,0,0,0.4);backdrop-filter:blur(4px);-webkit-backdrop-filter:blur(4px)} `; const slotRef = useRef(null); const cardRef = useRef(null); const placeholderRef = useRef(null); const cachedRef = useRef(null); const useLocalPreview = agentServer === "local" || agentServer === "prod" && isLocalhost(); const agentQuery = agentServer !== "local" && agentServer !== "prod" ? `?agentServer=${encodeURIComponent(agentServer)}` : ""; const sdkCacheKey = `${agentServer}|${pattern}`; const [sdk, setSdkRaw] = useState(() => { const fromCache = sdkCache.get(sdkCacheKey); if (fromCache) return fromCache; const hosts = useLocalPreview ? SDK_LOCAL_HOSTS : SDK_PROD_HOSTS; let best = null; for (const [s, url] of Object.entries(hosts)) { const entry = iframeCache.get(`${url}|${agentQuery}`); if (entry?.lastActiveAt && (!best || entry.lastActiveAt > best.at)) { best = { sdk: s, at: entry.lastActiveAt }; } } if (best) return best.sdk; return defaultSdk; }); const setSdk = useCallback(s => { sdkCache.set(sdkCacheKey, s); setSdkRaw(s); }, [sdkCacheKey]); const [sdkDropdownOpen, setSdkDropdownOpen] = useState(false); const langCacheKey = `${agentServer}|${pattern}`; const [agentLang, setAgentLangRaw] = useState(() => langCache.get(langCacheKey) ?? defaultLanguage); const setAgentLang = useCallback(l => { langCache.set(langCacheKey, l); setAgentLangRaw(l); }, [langCacheKey]); const previewUrl = useLocalPreview ? SDK_LOCAL_HOSTS[sdk] : SDK_PROD_HOSTS[sdk]; const cacheKey = `${previewUrl}|${agentQuery}`; const [ready, setReady] = useState(() => iframeCache.get(cacheKey)?.ready ?? false); const [iframeHeight, setIframeHeight] = useState(() => iframeCache.get(cacheKey)?.lastHeight ?? minHeight); const [error, setError] = useState(null); const [activeView, setActiveView] = useState(() => iframeCache.get(cacheKey)?.lastView ?? defaultView); const [traceUrl, setTraceUrl] = useState(null); const [traceLoading, setTraceLoading] = useState(false); const [expanded, setExpanded] = useState(false); const expandedRef = useRef(false); expandedRef.current = expanded; const [pageTheme, setPageTheme] = useState(detectPageTheme); useEffect(() => { setPageTheme(detectPageTheme()); const observer = new MutationObserver(() => setPageTheme(detectPageTheme())); observer.observe(document.documentElement, { attributes: true, attributeFilter: ["class", "data-theme", "style"] }); return () => observer.disconnect(); }, []); const effectiveTheme = theme ?? pageTheme; useEffect(() => { if (document.getElementById("lc-pe-css")) return; const style = document.createElement("style"); style.id = "lc-pe-css"; style.textContent = EMBED_CSS; document.head.appendChild(style); }, []); const onErrorRef = useRef(onError); onErrorRef.current = onError; const onReadyRef = useRef(onReady); onReadyRef.current = onReady; const patternRef = useRef(pattern); patternRef.current = pattern; const themeRef = useRef(effectiveTheme); themeRef.current = effectiveTheme; const activeViewRef = useRef(activeView); activeViewRef.current = activeView; const agentLangRef = useRef(agentLang); agentLangRef.current = agentLang; useEffect(() => { let cached = iframeCache.get(cacheKey); if (cached?.hideTimer) { clearTimeout(cached.hideTimer); cached.hideTimer = void 0; } if (!cached) { const iframe2 = document.createElement("iframe"); iframe2.src = `${previewUrl}/${agentQuery}#/${patternRef.current}`; iframe2.setAttribute("sandbox", "allow-scripts allow-same-origin allow-forms"); iframe2.setAttribute("allow", "clipboard-write"); iframe2.title = `${patternRef.current} pattern`; iframe2.setAttribute("data-cache-key", cacheKey); Object.assign(iframe2.style, { position: "fixed", border: "none", visibility: "hidden", pointerEvents: "auto", zIndex: "1", borderRadius: "0 0 15px 15px" }); document.body.appendChild(iframe2); let iframeOrigin; try { iframeOrigin = new URL(previewUrl).origin; } catch { iframeOrigin = previewUrl; } const host2 = createPreviewHost(iframe2, { allowedOrigins: [iframeOrigin] }); cached = { iframe: iframe2, host: host2, ready: false, lastHeight: minHeight, lastView: defaultView, lastActiveAt: 0 }; iframeCache.set(cacheKey, cached); } cachedRef.current = cached; const {iframe, host} = cached; if (cached.ready) { setReady(true); setIframeHeight(cached.lastHeight); host.setTheme(themeRef.current); host.setPattern(patternRef.current); host.setLanguage(agentLangRef.current); if (activeViewRef.current !== "preview") { host.setView(activeViewRef.current); } cached.lastActiveAt = Date.now(); iframe.style.visibility = "visible"; } const unsubReady = host.onReady(() => { cached.ready = true; cached.lastActiveAt = Date.now(); setReady(true); host.setTheme(themeRef.current); host.setPattern(patternRef.current); host.setLanguage(agentLangRef.current); if (activeViewRef.current !== "preview") { host.setView(activeViewRef.current); } iframe.style.visibility = "visible"; onReadyRef.current?.(); }); const unsubResize = host.onResize(h => { if (expandedRef.current) return; const clamped = Math.min(maxHeight, Math.max(minHeight, h)); cached.lastHeight = clamped; setIframeHeight(clamped); }); const unsubError = host.onError((message, stack) => { setError(message); iframe.style.visibility = "hidden"; onErrorRef.current?.(message, stack); }); const unsubRunStarted = host.onRunStarted(() => { setTraceUrl(null); setTraceLoading(true); }); const unsubTraceUrl = host.onTraceUrl((url, _runId) => { setTraceUrl(url); setTraceLoading(false); }); const unsubThreadCleared = host.onThreadCleared(() => { setTraceUrl(null); setTraceLoading(false); }); function syncPosition() { const slot2 = slotRef.current; if (!slot2) return; const rect = slot2.getBoundingClientRect(); const {style} = iframe; style.top = `${rect.top}px`; style.left = `${rect.left}px`; style.width = `${rect.width}px`; style.setProperty("height", `${rect.height}px`, "important"); if (expandedRef.current) { style.zIndex = "10000"; } else { style.zIndex = "1"; } } syncPosition(); const ro = new ResizeObserver(syncPosition); if (slotRef.current) ro.observe(slotRef.current); document.addEventListener("scroll", syncPosition, { passive: true, capture: true }); window.addEventListener("resize", syncPosition, { passive: true }); let frameCount = 0; let rafId = 0; function initialSync() { syncPosition(); if (++frameCount < 5) rafId = requestAnimationFrame(initialSync); } rafId = requestAnimationFrame(initialSync); return () => { cancelAnimationFrame(rafId); ro.disconnect(); document.removeEventListener("scroll", syncPosition, { capture: true }); window.removeEventListener("resize", syncPosition); unsubReady(); unsubResize(); unsubError(); unsubRunStarted(); unsubTraceUrl(); unsubThreadCleared(); cachedRef.current = null; cached.hideTimer = setTimeout(() => { iframe.style.visibility = "hidden"; }, 200); }; }, [cacheKey, previewUrl, agentQuery, defaultView, minHeight, maxHeight]); useEffect(() => { requestAnimationFrame(() => window.dispatchEvent(new Event("resize"))); if (!expanded) return; const card = cardRef.current; const placeholder = placeholderRef.current; if (!card || !placeholder) return; const wrapper = document.createElement("div"); wrapper.setAttribute("data-lc-pe", ""); wrapper.className = `${effectiveTheme === "dark" ? "dark" : ""}`; document.body.appendChild(wrapper); const backdrop = document.createElement("div"); backdrop.className = "lc-pe-backdrop"; backdrop.addEventListener("click", () => setExpanded(false)); wrapper.appendChild(backdrop); wrapper.appendChild(card); Object.assign(card.style, { position: "fixed", zIndex: "9999", top: "50%", left: "50%", transform: "translate(-50%, -50%)", width: "min(70vw, calc(100vw - 48px))", height: "85vh", display: "flex", flexDirection: "column" }); const handleKeyDown = e => { if (e.key === "Escape") setExpanded(false); }; document.addEventListener("keydown", handleKeyDown); const pageWrapper = document.body.children[0]; const savedFilter = pageWrapper?.style.filter ?? ""; const savedPointerEvents = pageWrapper?.style.pointerEvents ?? ""; if (pageWrapper && pageWrapper !== wrapper) { pageWrapper.style.filter = "blur(4px)"; pageWrapper.style.pointerEvents = "none"; } requestAnimationFrame(() => window.dispatchEvent(new Event("resize"))); return () => { document.removeEventListener("keydown", handleKeyDown); if (pageWrapper && pageWrapper !== wrapper) { pageWrapper.style.filter = savedFilter; pageWrapper.style.pointerEvents = savedPointerEvents; } card.style.cssText = ""; placeholder.appendChild(card); wrapper.remove(); requestAnimationFrame(() => window.dispatchEvent(new Event("resize"))); }; }, [expanded, effectiveTheme]); useEffect(() => { if (!ready || !cachedRef.current) return; setError(null); cachedRef.current.host.setPattern(pattern); }, [pattern, ready]); useEffect(() => { if (!ready || !cachedRef.current) return; cachedRef.current.host.setTheme(effectiveTheme); }, [effectiveTheme, ready]); useEffect(() => { if (!ready || !cachedRef.current) return; cachedRef.current.host.setLanguage(agentLang); }, [agentLang, ready]); const switchView = useCallback(view => { setActiveView(view); if (cachedRef.current) { cachedRef.current.lastView = view; if (cachedRef.current.ready) { cachedRef.current.host.setView(view); if (view === "code") { cachedRef.current.host.trackEvent("code_tab_clicked", { pattern }); } } } }, [pattern]); const sdkButtonRef = useRef(null); useEffect(() => { if (!sdkDropdownOpen || !sdkButtonRef.current) return; const isDark = effectiveTheme === "dark"; const rect = sdkButtonRef.current.getBoundingClientRect(); const dropdown = document.createElement("div"); Object.assign(dropdown.style, { position: "fixed", top: `${rect.bottom + 4}px`, right: `${window.innerWidth - rect.right}px`, zIndex: expandedRef.current ? "10001" : "10", minWidth: "120px", borderRadius: "8px", border: `1px solid ${isDark ? "#1A2740" : "#B8DFFF"}`, backgroundColor: isDark ? "#0B1120" : "white", boxShadow: "0 4px 12px rgba(0,0,0,0.15)", padding: "4px 0" }); for (const [value, label] of SDK_OPTIONS) { const isSelected = value === sdk; const btn = document.createElement("button"); btn.type = "button"; Object.assign(btn.style, { display: "flex", alignItems: "center", gap: "6px", width: "100%", textAlign: "left", padding: "6px 12px", fontSize: "13px", cursor: "pointer", border: "none", fontWeight: isSelected ? "500" : "normal", backgroundColor: isSelected ? isDark ? "#1A2740" : "#E5F4FF" : "transparent", color: isSelected ? isDark ? "#C8DDF0" : "#030710" : "#6B8299" }); btn.innerHTML = `${SDK_LOGOS[value]}${label}`; btn.addEventListener("mouseenter", () => { if (!isSelected) { btn.style.backgroundColor = isDark ? "#1A2740" : "#F2FAFF"; btn.style.color = isDark ? "#C8DDF0" : "#030710"; } }); btn.addEventListener("mouseleave", () => { if (!isSelected) { btn.style.backgroundColor = "transparent"; btn.style.color = "#6B8299"; } }); btn.addEventListener("click", () => { setSdk(value); setSdkDropdownOpen(false); cachedRef.current?.host.trackEvent("sdk_switched", { sdk: value, pattern }); }); dropdown.appendChild(btn); } document.body.appendChild(dropdown); const handleClose = e => { if (!dropdown.contains(e.target) && !sdkButtonRef.current?.contains(e.target)) { setSdkDropdownOpen(false); } }; const timer = setTimeout(() => document.addEventListener("mousedown", handleClose), 0); return () => { clearTimeout(timer); document.removeEventListener("mousedown", handleClose); dropdown.remove(); }; }, [sdkDropdownOpen, sdk, effectiveTheme, setSdk, pattern]); const handleReset = useCallback(() => { cachedRef.current?.host.reset(); if (cachedRef.current?.ready) { cachedRef.current.host.setPattern(pattern); } }, [pattern]); const resolvedHeight = height ?? Math.min(maxHeight, Math.max(minHeight, iframeHeight)); const heightStyle = typeof resolvedHeight === "number" ? `${resolvedHeight}px` : resolvedHeight; useEffect(() => { if (!expanded) { slotRef.current?.style.setProperty("height", heightStyle, "important"); } else { slotRef.current?.style.removeProperty("height"); } }, [heightStyle, expanded]); const tabBase = "lc-tab inline-flex items-center gap-1.5 px-3.5 py-1.5 rounded-lg border-none font-medium cursor-pointer transition-all duration-150"; const tabActiveClass = `${tabBase} lc-tab-active shadow-sm`; const tabInactiveClass = `${tabBase} lc-tab-inactive`; const tabTraceActiveClass = `${tabBase} lc-tab-trace`; const tabTraceLoadingClass = `${tabBase} lc-tab-trace-loading`; const toolbar = showCodeTab &&
{(traceUrl || traceLoading) && !useLocalPreview && { if (!traceUrl) e.preventDefault(); else cachedRef.current?.host.trackEvent("trace_tab_clicked", { pattern }); }} className={traceUrl ? tabTraceActiveClass : tabTraceLoadingClass} aria-disabled={!traceUrl}> Trace {traceUrl && } }
{activeView === "code" &&
}
{} {}
; const slot =
{!ready && !error &&
} {error &&
Preview Error

{error}

}
; return
{toolbar} {slot}
; }; LangGraph 智能体并非黑盒。每个图都由**命名节点**组成，这些节点按顺序或并行执行：分类、研究、分析、综合。图执行卡片通过为每个节点渲染一张卡片，显示其状态、实时流式传输其内容，并跟踪整个工作流的完成情况，使这一流水线变得可见。用户可以清晰地看到智能体正在做什么、当前处于哪一步骤，以及每个步骤产生了什么结果。 ## 图节点如何映射到 UI 卡片 一个 LangGraph 图定义了一系列节点，每个节点负责一项特定任务。例如，一个研究流水线可能包含： 1. **分类**：对用户查询进行分类 2. **研究**：收集相关信息 3. **分析**：从研究中得出结论 4. **综合**：生成最终的、经过润色的响应 每个节点将其输出写入图状态的特定键。通过将这些节点名称和状态键映射到 UI 组件，您可以创建整个流水线的可视化表示。 ```ts theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}} const PIPELINE_NODES = [ { name: "classify", stateKey: "classification", label: "分类" }, { name: "do_research", stateKey: "research", label: "研究" }, { name: "analyze", stateKey: "analysis", label: "分析" }, { name: "synthesize", stateKey: "synthesis", label: "综合" }, ]; const PIPELINE_NODE_NAMES = new Set(PIPELINE_NODES.map((n) => n.name)); ``` ## 设置 useStream 像往常一样连接 `useStream`。您将使用的关键属性是 `messages`（用于流式内容路由）、`values`（用于已完成的节点输出）和 `getMessagesMetadata`（用于识别每个令牌是由哪个节点产生的）。 导入您的智能体，并将 `typeof myAgent` 作为类型参数传递给 `useStream`，以便对状态值进行类型安全访问： ```ts theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}} import type { myAgent } from "./agent"; ``` ```tsx React theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}} import { useStream } from "@langchain/react"; const AGENT_URL = "http://localhost:2024"; export function PipelineChat() { const stream = useStream({ apiUrl: AGENT_URL, assistantId: "graph_execution_cards", }); return (
); } ``` ```vue Vue theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}} ``` ```svelte Svelte theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}}
``` ```ts Angular theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}} import { Component } from "@angular/core"; import { useStream } from "@langchain/angular"; const AGENT_URL = "http://localhost:2024"; @Component({ selector: "app-pipeline-chat", template: `
`, }) export class PipelineChatComponent { PIPELINE_NODES = PIPELINE_NODES; stream = useStream({ apiUrl: AGENT_URL, assistantId: "graph_execution_cards", }); } ``` ## 将流式令牌路由到节点 当智能体流式传输时，每条消息都附有元数据，用于标识是哪个图节点产生了它。使用 `getMessagesMetadata` 提取 `langgraph_node` 值，并将令牌路由到正确的卡片： ```ts theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}} function getStreamingContent( messages: BaseMessage[], getMetadata: (msg: BaseMessage) => MessageMetadata | undefined ): Record { const content: Record = {}; for (const message of messages) { if (message.type !== "ai") continue; const metadata = getMetadata(message); const node = metadata?.streamMetadata?.langgraph_node; if (node && PIPELINE_NODE_NAMES.has(node)) { content[node] = typeof message.content === "string" ? message.content : ""; } } return content; } ``` 这为您提供了一个从节点名称到其当前流式内容的映射。随着令牌到达，相应的卡片会实时更新。 `streamMetadata.langgraph_node` 字段由 LangGraph 自动设置。您在后端不需要任何特殊配置。只需像往常一样流式传输消息，元数据就会包含在内。 ## 确定节点状态 每个节点可能处于四种状态之一：未开始、流式传输中、已完成或空闲。您可以从两个来源推导出状态：流式内容映射（用于活动节点）和 `stream.values`（用于已完成的节点）： ```ts theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}} type NodeStatus = "idle" | "streaming" | "complete"; function getNodeStatus( node: { name: string; stateKey: string }, streamingContent: Record, values: Record ): NodeStatus { if (values?.[node.stateKey]) return "complete"; if (streamingContent[node.name]) return "streaming"; return "idle"; } ``` ## 构建流水线进度条 顶部的水平进度条为用户提供了整个流水线的鸟瞰视图。每个步骤都是一个带标签的段，随着节点完成而填充： ```tsx theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}} function PipelineProgress({ nodes, values, streamingContent, }: { nodes: typeof PIPELINE_NODES; values: Record; streamingContent: Record; }) { return (
{nodes.map((node, i) => { const status = getNodeStatus(node, streamingContent, values); const colors = { idle: "bg-gray-200 text-gray-500", streaming: "bg-blue-400 text-white animate-pulse", complete: "bg-green-500 text-white", }; return (
{node.label}
{i < nodes.length - 1 && (
)}
); })}
); } ``` ## 构建可折叠的 NodeCard 组件 每个节点都有自己的卡片，显示状态徽章、内容（流式或最终）以及用于长输出的可折叠主体： ```tsx theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}} function NodeCard({ node, status, streamingContent, completedContent, }: { node: { name: string; stateKey: string; label: string }; status: NodeStatus; streamingContent: string | undefined; completedContent: unknown; }) { const [collapsed, setCollapsed] = useState(false); const displayContent = status === "complete" ? formatContent(completedContent) : streamingContent ?? ""; const statusBadge = { idle: { text: "等待中", className: "bg-gray-100 text-gray-600" }, streaming: { text: "运行中", className: "bg-blue-100 text-blue-700 animate-pulse", }, complete: { text: "已完成", className: "bg-green-100 text-green-700" }, }; const badge = statusBadge[status]; return (
{!collapsed && displayContent && (
{displayContent} {status === "streaming" && ( )}
)}
); } function formatContent(value: unknown): string { if (typeof value === "string") return value; if (value == null) return ""; return JSON.stringify(value, null, 2); } ``` ## 流式内容与已完成内容 每个节点有两个内容来源，选择合适的来源对于流畅的用户体验很重要： | 来源 | 何时使用 | | ------------------------------ | ----------------------- | | `streamingContent[node.name]` | 当节点正在主动流式传输时，此属性包含到达的令牌 | | `stream.values[node.stateKey]` | 节点完成后，此属性包含最终的、已提交的输出 | 模式是：显示流式内容以获取实时更新，节点完成后回退到已提交的状态值。 ```ts theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}} for (const node of PIPELINE_NODES) { const status = getNodeStatus(node, streamingContent, stream.values); const content = status === "streaming" ? streamingContent[node.name] : stream.values?.[node.stateKey]; } ``` 流式内容可能包含部分令牌或尚未完全形成的 Markdown。如果您渲染 Markdown，请确保您的渲染器能够优雅地处理不完整的语法（例如，未闭合的粗体标记 `**`）。 ## 整体整合 以下是结合了路由、状态检测和卡片渲染的完整卡片列表： ```tsx theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}} function NodeCardList({ nodes, messages, values, getMetadata, }: { nodes: typeof PIPELINE_NODES; messages: BaseMessage[]; values: Record; getMetadata: (msg: BaseMessage) => MessageMetadata | undefined; }) { const streamingContent = getStreamingContent(messages, getMetadata); return (
{nodes.map((node) => { const status = getNodeStatus(node, streamingContent, values); return ( ); })}
); } ``` ## 使用场景 图执行卡片适用于任何需要可见性的多步骤流水线： * **研究流水线**：分类 → 收集来源 → 分析 → 综合报告 * **内容生成**：大纲 → 草稿 → 事实核查 → 编辑 → 发布 * **数据处理**：摄取 → 验证 → 转换 → 聚合 → 导出 * **代码生成**：理解需求 → 规划架构 → 编写代码 → 审查 → 测试 * **决策工作流**：收集上下文 → 评估选项 → 评分备选方案 → 推荐 ## 处理动态流水线 并非所有图都有固定的节点集。一些流水线会根据输入添加或跳过节点。通过检查哪些状态键实际有值来处理这种情况： ```ts theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}} const activeNodes = PIPELINE_NODES.filter( (node) => streamingContent[node.name] || values?.[node.stateKey] || node.name === currentNode ); ``` 这确保您的 UI 只显示与当前执行相关的节点的卡片，避免出现空的占位卡片。 如果您的图具有条件分支（例如，对于简单的查询跳过“研究”步骤），被跳过的节点将永远不会出现在流式内容或状态值中。您的流水线进度条应通过变灰或隐藏跳过的步骤来反映这一点。 ## 最佳实践 * **声明式定义节点**。将您的 `PIPELINE_NODES` 数组作为单一事实来源，映射节点名称、状态键和显示标签。 * **优先使用流式内容处理活动节点**。它为用户提供即时反馈。仅在节点完成后才回退到已提交的状态值。 * **自动折叠已完成的节点**。在长流水线中，自动折叠已完成的卡片，以便用户可以专注于当前活动的步骤。 * **显示预估时间**。如果您有每个节点所需时间的历史数据，请显示时间预估以设定用户期望。 * **添加全局进度指示器**。在流水线视图的顶部，用整体进度条（例如，“第 2 步，共 4 步”）来补充每个节点的卡片。 * **按节点处理错误**。如果某个节点失败，在其卡片中显示错误，而不要折叠整个流水线。其他节点可能仍会成功完成。 ***
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