perf(ui): lazy-load markdown and defer diff rendering (#215)

## Summary - lazy-load the markdown and diff render paths so they stop inflating initial UI startup work - move shared text rendering helpers out of the markdown path and keep diff rendering on the deferred path - defer the Monaco secondary viewers so the markdown and diff path no longer keeps that work in the main bundle ## Follow-ups - related fork follow-up: Pagecran/CodeNomad#1 - that follow-up is now independent on dev and only keeps the remaining right panel, picker, and tool-call secondary chunking work ## Testing - npm run typecheck --workspace @codenomad/ui - npm run build --workspace @codenomad/ui
2026-03-22 12:54:05 +01:00
parent d15340a4b8
commit 74f753abf4
20 changed files with 459 additions and 270 deletions
--- a/packages/ui/src/components/markdown.tsx
+++ b/packages/ui/src/components/markdown.tsx
@@ -1,5 +1,4 @@
 import { createEffect, createMemo, createSignal, onCleanup, onMount } from "solid-js"
-import { renderMarkdown, onLanguagesLoaded, decodeHtmlEntities, setMarkdownTheme } from "../lib/markdown"
 import { useGlobalCache } from "../lib/hooks/use-global-cache"
 import type { TextPart, RenderCache } from "../types/message"
 import { getLogger } from "../lib/logger"
@@ -8,6 +7,20 @@ import { useI18n } from "../lib/i18n"

 const log = getLogger("session")

+type MarkdownModule = typeof import("../lib/markdown")
+
+let markdownModulePromise: Promise<MarkdownModule> | null = null
+
+function loadMarkdownModule(): Promise<MarkdownModule> {
+  if (!markdownModulePromise) {
+    markdownModulePromise = import("../lib/markdown").catch((error) => {
+      markdownModulePromise = null
+      throw error
+    })
+  }
+  return markdownModulePromise
+}
+
 function hashText(value: string): string {
  let hash = 2166136261
  for (let index = 0; index < value.length; index++) {
@@ -24,6 +37,45 @@ function resolvePartVersion(part: TextPart, text: string): string {
  return `text-${hashText(text)}`
 }

+function resolvePartCacheId(part: TextPart, text: string): string {
+  const partId = typeof part.id === "string" && part.id.length > 0 ? part.id : ""
+  if (partId) {
+    return partId
+  }
+
+  return `anonymous:${hashText(text)}`
+}
+
+function decodeHtmlEntitiesLocally(content: string): string {
+  if (!content.includes("&") || typeof document === "undefined") {
+    return content
+  }
+
+  const textarea = document.createElement("textarea")
+  textarea.innerHTML = content
+  return textarea.value
+}
+
+function escapeHtml(content: string): string {
+  const map: Record<string, string> = {
+    "&": "&amp;",
+    "<": "&lt;",
+    ">": "&gt;",
+    '"': "&quot;",
+    "'": "&#039;",
+  }
+
+  return content.replace(/[&<>"']/g, (match) => map[match] ?? match)
+}
+
+function renderFallbackHtml(content: string): string {
+  if (!content) {
+    return ""
+  }
+
+  return escapeHtml(content).replace(/\n/g, "<br />")
+}
+
 interface MarkdownProps {
  part: TextPart
  instanceId?: string
@@ -38,7 +90,8 @@ export function Markdown(props: MarkdownProps) {
  const { t } = useI18n()
  const [html, setHtml] = createSignal("")
  let containerRef: HTMLDivElement | undefined
-  let latestRequestedText = ""
+  let latestRequestKey = ""
+  let cleanupLanguageListener: (() => void) | undefined

  const notifyRendered = () => {
    Promise.resolve().then(() => props.onRendered?.())
@@ -47,15 +100,14 @@ export function Markdown(props: MarkdownProps) {
  const resolved = createMemo(() => {
    const part = props.part
    const rawText = typeof part.text === "string" ? part.text : ""
-    const text = decodeHtmlEntities(rawText)
+    const text = decodeHtmlEntitiesLocally(rawText)
    const themeKey = Boolean(props.isDark) ? "dark" : "light"
    const highlightEnabled = !props.disableHighlight
-    const partId = typeof part.id === "string" && part.id.length > 0 ? part.id : ""
-    if (!partId) {
-      throw new Error("Markdown rendering requires a part id")
-    }
+    const partId = typeof part.id === "string" && part.id.length > 0 ? part.id : undefined
+    const cacheId = resolvePartCacheId(part, text)
    const version = resolvePartVersion(part, text)
-    return { part, text, themeKey, highlightEnabled, partId, version }
+    const requestKey = `${cacheId}:${themeKey}:${highlightEnabled ? 1 : 0}:${version}`
+    return { part, text, themeKey, highlightEnabled, partId, cacheId, version, requestKey }
  })

  const cacheHandle = useGlobalCache({
@@ -63,26 +115,46 @@ export function Markdown(props: MarkdownProps) {
    sessionId: () => props.sessionId,
    scope: "markdown",
    cacheId: () => {
-      const { partId, themeKey, highlightEnabled } = resolved()
-      return `${partId}:${themeKey}:${highlightEnabled ? 1 : 0}`
+      const { cacheId, themeKey, highlightEnabled } = resolved()
+      return `${cacheId}:${themeKey}:${highlightEnabled ? 1 : 0}`
    },
    version: () => resolved().version,
  })

-  createEffect(async () => {
-    const { part, text, themeKey, highlightEnabled, version } = resolved()
+  const commitCacheEntry = (snapshot: ReturnType<typeof resolved>, renderedHtml: string) => {
+    const cacheEntry: RenderCache = {
+      text: snapshot.text,
+      html: renderedHtml,
+      theme: snapshot.themeKey,
+      mode: snapshot.version,
+    }
+    setHtml(renderedHtml)
+    cacheHandle.set(cacheEntry)
+    notifyRendered()
+  }

-    // Ensure the markdown highlighter theme matches the active UI theme.
-    setMarkdownTheme(themeKey === "dark")
+  const renderSnapshot = async (snapshot: ReturnType<typeof resolved>) => {
+    const markdown = await loadMarkdownModule()
+    markdown.setMarkdownTheme(snapshot.themeKey === "dark")
+    const rendered = await markdown.renderMarkdown(snapshot.text, {
+      suppressHighlight: !snapshot.highlightEnabled,
+    })

-    latestRequestedText = text
+    if (latestRequestKey === snapshot.requestKey) {
+      commitCacheEntry(snapshot, rendered)
+    }
+  }
+
+  createEffect(() => {
+    const snapshot = resolved()
+    latestRequestKey = snapshot.requestKey

    const cacheMatches = (cache: RenderCache | undefined) => {
      if (!cache) return false
-      return cache.theme === themeKey && cache.mode === version
+      return cache.theme === snapshot.themeKey && cache.mode === snapshot.version
    }

-    const localCache = part.renderCache
+    const localCache = snapshot.part.renderCache
    if (localCache && cacheMatches(localCache)) {
      setHtml(localCache.html)
      notifyRendered()
@@ -96,111 +168,82 @@ export function Markdown(props: MarkdownProps) {
      return
    }

-    const commitCacheEntry = (renderedHtml: string) => {
-      const cacheEntry: RenderCache = { text, html: renderedHtml, theme: themeKey, mode: version }
-      setHtml(renderedHtml)
-      cacheHandle.set(cacheEntry)
-      notifyRendered()
-    }
+    setHtml(renderFallbackHtml(snapshot.text))
+    notifyRendered()

-    if (!highlightEnabled) {
-      try {
-        const rendered = await renderMarkdown(text, { suppressHighlight: true })
-
-        if (latestRequestedText === text) {
-          commitCacheEntry(rendered)
-        }
-      } catch (error) {
-        log.error("Failed to render markdown:", error)
-        if (latestRequestedText === text) {
-          commitCacheEntry(text)
-        }
-      }
-      return
-    }
-
-    try {
-      const rendered = await renderMarkdown(text)
-      if (latestRequestedText === text) {
-        commitCacheEntry(rendered)
-      }
-    } catch (error) {
+    void renderSnapshot(snapshot).catch((error) => {
      log.error("Failed to render markdown:", error)
-      if (latestRequestedText === text) {
-        commitCacheEntry(text)
+      if (latestRequestKey === snapshot.requestKey) {
+        commitCacheEntry(snapshot, renderFallbackHtml(snapshot.text))
      }
-    }
+    })
  })

  onMount(() => {
-    const handleClick = async (e: Event) => {
-      const target = e.target as HTMLElement
+    const handleClick = async (event: Event) => {
+      const target = event.target as HTMLElement
      const copyButton = target.closest(".code-block-copy") as HTMLButtonElement

-      if (copyButton) {
-        e.preventDefault()
-        const code = copyButton.getAttribute("data-code")
-        if (code) {
-          const decodedCode = decodeURIComponent(code)
-          const success = await copyToClipboard(decodedCode)
-          const copyText = copyButton.querySelector(".copy-text")
-          if (copyText) {
-            if (success) {
-              copyText.textContent = t("markdown.codeBlock.copy.copied")
-              setTimeout(() => {
-                copyText.textContent = t("markdown.codeBlock.copy.label")
-              }, 2000)
-            } else {
-              copyText.textContent = t("markdown.codeBlock.copy.failed")
-              setTimeout(() => {
-                copyText.textContent = t("markdown.codeBlock.copy.label")
-              }, 2000)
-            }
-          }
-        }
+      if (!copyButton) {
+        return
      }
+
+      event.preventDefault()
+      const code = copyButton.getAttribute("data-code")
+      if (!code) {
+        return
+      }
+
+      const decodedCode = decodeURIComponent(code)
+      const success = await copyToClipboard(decodedCode)
+      const copyText = copyButton.querySelector(".copy-text")
+      if (!copyText) {
+        return
+      }
+
+      copyText.textContent = success ? t("markdown.codeBlock.copy.copied") : t("markdown.codeBlock.copy.failed")
+      setTimeout(() => {
+        copyText.textContent = t("markdown.codeBlock.copy.label")
+      }, 2000)
    }

    containerRef?.addEventListener("click", handleClick)

-    const cleanupLanguageListener = onLanguagesLoaded(async () => {
-      if (props.disableHighlight) {
-        return
-      }
-
-      const { part, text, themeKey, version } = resolved()
-
-      setMarkdownTheme(themeKey === "dark")
-
-      if (latestRequestedText !== text) {
-        return
-      }
-
-      try {
-        const rendered = await renderMarkdown(text)
-        if (latestRequestedText === text) {
-          const cacheEntry: RenderCache = { text, html: rendered, theme: themeKey, mode: version }
-          setHtml(rendered)
-          cacheHandle.set(cacheEntry)
-          notifyRendered()
+    let disposed = false
+    void loadMarkdownModule()
+      .then((markdown) => {
+        if (disposed) {
+          return
        }
-      } catch (error) {
-        log.error("Failed to re-render markdown after language load:", error)
-      }
-    })
+
+        cleanupLanguageListener = markdown.onLanguagesLoaded(() => {
+          const snapshot = resolved()
+          if (!snapshot.highlightEnabled) {
+            return
+          }
+
+          latestRequestKey = snapshot.requestKey
+          void renderSnapshot(snapshot).catch((error) => {
+            log.error("Failed to re-render markdown after language load:", error)
+          })
+        })
+      })
+      .catch((error) => {
+        log.error("Failed to load markdown module:", error)
+      })

    onCleanup(() => {
+      disposed = true
      containerRef?.removeEventListener("click", handleClick)
-      cleanupLanguageListener()
+      cleanupLanguageListener?.()
+      cleanupLanguageListener = undefined
    })
  })

-  const proseClass = () => "markdown-body"
-
  return (
    <div
      ref={containerRef}
-      class={proseClass()}
+      class="markdown-body"
      data-view="markdown"
      data-part-id={resolved().partId}
      data-markdown-theme={resolved().themeKey}