From d18e44f72150b7136531876a83a95c2c2aa3a034 Mon Sep 17 00:00:00 2001
From: Shantur Rathore <i@shantur.com>
Date: Tue, 28 Oct 2025 14:41:09 +0000
Subject: [PATCH] Cache markdown render output per message part

---
 src/components/markdown.tsx     | 104 ++++++++++++++++----------------
 src/components/message-part.tsx |   4 +-
 src/components/tool-call.tsx    |   6 +-
 src/lib/markdown.ts             |  44 ++++++++++++--
 src/stores/sessions.ts          |  32 +++++++++-
 src/types/message.ts            |  13 ++++
 6 files changed, 140 insertions(+), 63 deletions(-)

diff --git a/src/components/markdown.tsx b/src/components/markdown.tsx
index a0db2f58..fccfe718 100644
--- a/src/components/markdown.tsx
+++ b/src/components/markdown.tsx
@@ -1,72 +1,70 @@
-import { createEffect, createSignal, Show } from "solid-js"
+import { createEffect, createSignal, onMount, onCleanup } from "solid-js"
 import { renderMarkdown } from "../lib/markdown"
+import type { TextPart } from "../types/message"
 
 interface MarkdownProps {
-  content: string
+  part: TextPart
   isDark?: boolean
 }
 
 export function Markdown(props: MarkdownProps) {
   const [html, setHtml] = createSignal("")
   let containerRef: HTMLDivElement | undefined
+  let latestRequestedText = ""
 
   createEffect(async () => {
-    const rendered = await renderMarkdown(props.content)
-    setHtml(rendered)
+    const part = props.part
+    const text = part.text || ""
+
+    if (part.renderCache && part.renderCache.text === text) {
+      setHtml(part.renderCache.html)
+      return
+    }
+
+    latestRequestedText = text
+
+    try {
+      const rendered = await renderMarkdown(text)
+
+      if (latestRequestedText === text) {
+        setHtml(rendered)
+        part.renderCache = { text, html: rendered }
+      }
+    } catch (error) {
+      console.error("Failed to render markdown:", error)
+      if (latestRequestedText === text) {
+        setHtml(text)
+      }
+    }
   })
 
-  createEffect(() => {
-    const currentHtml = html()
-    if (containerRef && currentHtml) {
-      setTimeout(() => {
-        const codeBlocks = containerRef?.querySelectorAll(".markdown-code-block")
+  onMount(() => {
+    const handleClick = async (e: Event) => {
+      const target = e.target as HTMLElement
+      const copyButton = target.closest(".code-block-copy") as HTMLButtonElement
 
-        codeBlocks?.forEach((block) => {
-          const existing = block.querySelector(".code-block-header")
-          if (existing) return
-
-          const lang = block.getAttribute("data-language")
-          const encodedCode = block.getAttribute("data-code")
-
-          const header = document.createElement("div")
-          header.className = "code-block-header"
-
-          const languageSpan = lang
-            ? `<span class="code-block-language">${lang}</span>`
-            : '<span class="code-block-language"></span>'
-
-          header.innerHTML = `
-          ${languageSpan}
-          <button class="code-block-copy" data-code="${encodedCode || ""}">
-            <svg class="copy-icon" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
-              <rect x="9" y="9" width="13" height="13" rx="2" ry="2"></rect>
-              <path d="M5 15H4a2 2 0 0 1-2-2V4a2 2 0 0 1 2-2h9a2 2 0 0 1 2 2v1"></path>
-            </svg>
-            <span class="copy-text">Copy</span>
-          </button>
-        `
-          block.insertBefore(header, block.firstChild)
-
-          const button = header.querySelector(".code-block-copy")
-          if (button) {
-            button.addEventListener("click", async () => {
-              const code = button.getAttribute("data-code")
-              if (code) {
-                const decodedCode = decodeURIComponent(code)
-                await navigator.clipboard.writeText(decodedCode)
-                const copyText = button.querySelector(".copy-text")
-                if (copyText) {
-                  copyText.textContent = "Copied!"
-                  setTimeout(() => {
-                    copyText.textContent = "Copy"
-                  }, 2000)
-                }
-              }
-            })
+      if (copyButton) {
+        e.preventDefault()
+        const code = copyButton.getAttribute("data-code")
+        if (code) {
+          const decodedCode = decodeURIComponent(code)
+          await navigator.clipboard.writeText(decodedCode)
+          const copyText = copyButton.querySelector(".copy-text")
+          if (copyText) {
+            copyText.textContent = "Copied!"
+            setTimeout(() => {
+              copyText.textContent = "Copy"
+            }, 2000)
           }
-        })
-      }, 0)
+        }
+      }
     }
+
+    containerRef?.addEventListener("click", handleClick)
+
+    onCleanup(() => {
+      containerRef?.removeEventListener("click", handleClick)
+    })
   })
 
   return <div ref={containerRef} class="prose prose-sm dark:prose-invert max-w-none" innerHTML={html()} />
diff --git a/src/components/message-part.tsx b/src/components/message-part.tsx
index 521ab99b..fe4535e3 100644
--- a/src/components/message-part.tsx
+++ b/src/components/message-part.tsx
@@ -25,7 +25,7 @@ export default function MessagePart(props: MessagePartProps) {
       <Match when={partType() === "text"}>
         <Show when={!props.part.synthetic && props.part.text}>
           <div class="message-text">
-            <Markdown content={props.part.text} isDark={isDark()} />
+            <Markdown part={props.part} isDark={isDark()} />
           </div>
         </Show>
       </Match>
@@ -48,7 +48,7 @@ export default function MessagePart(props: MessagePartProps) {
               </div>
               <Show when={isReasoningExpanded()}>
                 <div class="message-text mt-2">
-                  <Markdown content={props.part.text || ""} isDark={isDark()} />
+                  <Markdown part={props.part} isDark={isDark()} />
                 </div>
               </Show>
             </div>
diff --git a/src/components/tool-call.tsx b/src/components/tool-call.tsx
index cd6e2d29..8a5a0109 100644
--- a/src/components/tool-call.tsx
+++ b/src/components/tool-call.tsx
@@ -357,7 +357,7 @@ export default function ToolCall(props: ToolCallProps) {
         return (
           <div class="tool-call-bash">
             <div class="message-text">
-              <Markdown content={fullOutput} isDark={isDark()} />
+              <Markdown part={{ type: "text", text: fullOutput }} isDark={isDark()} />
             </div>
           </div>
         )
@@ -384,7 +384,7 @@ export default function ToolCall(props: ToolCallProps) {
       if (hasMarkdownCodeBlocks(truncated)) {
         return (
           <div class="message-text">
-            <Markdown content={truncated} isDark={isDark()} />
+            <Markdown part={{ type: "text", text: truncated }} isDark={isDark()} />
           </div>
         )
       }
@@ -479,7 +479,7 @@ export default function ToolCall(props: ToolCallProps) {
       if (hasMarkdownCodeBlocks(truncated)) {
         return (
           <div class="message-text">
-            <Markdown content={truncated} isDark={isDark()} />
+            <Markdown part={{ type: "text", text: truncated }} isDark={isDark()} />
           </div>
         )
       }
diff --git a/src/lib/markdown.ts b/src/lib/markdown.ts
index 2899720c..191056a1 100644
--- a/src/lib/markdown.ts
+++ b/src/lib/markdown.ts
@@ -1,6 +1,27 @@
 import { marked } from "marked"
 import { createHighlighter, type Highlighter, bundledLanguages } from "shiki/bundle/full"
 
+const CORE_LANGUAGES = [
+  "bash",
+  "shell",
+  "sh",
+  "javascript",
+  "typescript",
+  "tsx",
+  "jsx",
+  "json",
+  "yaml",
+  "yml",
+  "markdown",
+  "md",
+  "html",
+  "css",
+  "scss",
+  "python",
+  "go",
+  "rust",
+]
+
 let highlighter: Highlighter | null = null
 let highlighterPromise: Promise<Highlighter> | null = null
 let currentTheme: "light" | "dark" = "light"
@@ -15,9 +36,11 @@ async function getOrCreateHighlighter() {
     return highlighterPromise
   }
 
+  const filteredLangs = CORE_LANGUAGES.filter((lang) => lang in bundledLanguages)
+
   highlighterPromise = createHighlighter({
     themes: ["github-light", "github-dark"],
-    langs: Object.keys(bundledLanguages),
+    langs: filteredLangs,
   })
 
   highlighter = await highlighterPromise
@@ -41,8 +64,21 @@ function setupRenderer(isDark: boolean) {
     const encodedCode = encodeURIComponent(code)
     const escapedLang = lang ? escapeHtml(lang) : ""
 
+    const header = `
+      <div class="code-block-header">
+        <span class="code-block-language">${escapedLang || ""}</span>
+        <button class="code-block-copy" data-code="${encodedCode}">
+          <svg class="copy-icon" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
+            <rect x="9" y="9" width="13" height="13" rx="2" ry="2"></rect>
+            <path d="M5 15H4a2 2 0 0 1-2-2V4a2 2 0 0 1 2-2h9a2 2 0 0 1 2 2v1"></path>
+          </svg>
+          <span class="copy-text">Copy</span>
+        </button>
+      </div>
+    `
+
     if (!lang || !highlighter) {
-      return `<div class="markdown-code-block" data-language="" data-code="${encodedCode}"><pre><code>${escapeHtml(code)}</code></pre></div>`
+      return `<div class="markdown-code-block" data-language="${escapedLang}" data-code="${encodedCode}">${header}<pre><code>${escapeHtml(code)}</code></pre></div>`
     }
 
     try {
@@ -50,9 +86,9 @@ function setupRenderer(isDark: boolean) {
         lang,
         theme: isDark ? "github-dark" : "github-light",
       })
-      return `<div class="markdown-code-block" data-language="${escapedLang}" data-code="${encodedCode}">${html}</div>`
+      return `<div class="markdown-code-block" data-language="${escapedLang}" data-code="${encodedCode}">${header}${html}</div>`
     } catch {
-      return `<div class="markdown-code-block" data-language="${escapedLang}" data-code="${encodedCode}"><pre><code class="language-${escapedLang}">${escapeHtml(code)}</code></pre></div>`
+      return `<div class="markdown-code-block" data-language="${escapedLang}" data-code="${encodedCode}">${header}<pre><code class="language-${escapedLang}">${escapeHtml(code)}</code></pre></div>`
     }
   }
 
diff --git a/src/stores/sessions.ts b/src/stores/sessions.ts
index 1fddfae0..6a50ef80 100644
--- a/src/stores/sessions.ts
+++ b/src/stores/sessions.ts
@@ -706,11 +706,19 @@ async function loadMessages(instanceId: string, sessionId: string, force = false
 
       messagesInfo.set(messageId, info)
 
+      // Clear render cache for all parts when loading messages
+      const parts = (apiMessage.parts || []).map((part: any) => {
+        if (part.type === "text") {
+          return { ...part, renderCache: undefined }
+        }
+        return part
+      })
+
       const message: Message = {
         id: messageId,
         sessionId,
         type: role === "user" ? "user" : "assistant",
-        parts: apiMessage.parts || [],
+        parts,
         timestamp: info.time?.created || Date.now(),
         status: "complete" as const,
         version: 0,
@@ -855,12 +863,24 @@ function handleMessageUpdate(instanceId: string, event: any): void {
       if (message.parts.some((partItem: any) => partItem.synthetic === true)) {
         message.parts = message.parts.filter((partItem: any) => partItem.synthetic !== true)
         filteredSynthetics = true
+        // Clear render cache from remaining parts when synthetic parts are removed
+        message.parts.forEach((partItem: any) => {
+          if (partItem.type === "text") {
+            partItem.renderCache = undefined
+          }
+        })
       }
 
       let baseParts: any[]
       if (replacedTemp) {
         baseParts = message.parts.filter((partItem: any) => partItem.type !== "text")
         message.parts = baseParts
+        // Clear render cache when replacing temp content
+        baseParts.forEach((partItem: any) => {
+          if (partItem.type === "text") {
+            partItem.renderCache = undefined
+          }
+        })
       } else {
         baseParts = message.parts
       }
@@ -881,6 +901,10 @@ function handleMessageUpdate(instanceId: string, event: any): void {
           partMap.set(part.id, baseParts.length - 1)
         }
         shouldIncrementVersion = true
+        // Clear render cache for new text parts
+        if (part.type === "text") {
+          part.renderCache = undefined
+        }
       } else {
         const previousPart = baseParts[partIndex]
         const textUnchanged =
@@ -897,6 +921,10 @@ function handleMessageUpdate(instanceId: string, event: any): void {
         baseParts[partIndex] = part
         if (part.type !== "text" || !previousPart || previousPart.text !== part.text) {
           shouldIncrementVersion = true
+          // Clear render cache when text changes
+          if (part.type === "text") {
+            part.renderCache = undefined
+          }
         }
       }
 
@@ -1147,6 +1175,7 @@ async function sendMessage(
       type: "text" as const,
       text: prompt,
       synthetic: true,
+      renderCache: undefined,
     },
   ]
 
@@ -1208,6 +1237,7 @@ async function sendMessage(
           type: "text" as const,
           text: source.value,
           synthetic: true,
+          renderCache: undefined,
         })
       }
     }
diff --git a/src/types/message.ts b/src/types/message.ts
index c2a54ec8..51b47914 100644
--- a/src/types/message.ts
+++ b/src/types/message.ts
@@ -1,3 +1,8 @@
+export interface RenderCache {
+  text: string
+  html: string
+}
+
 export interface MessageDisplayParts {
   text: any[]
   tool: any[]
@@ -17,3 +22,11 @@ export interface Message {
   version: number
   displayParts?: MessageDisplayParts
 }
+
+export interface TextPart {
+  id?: string
+  type: "text"
+  text: string
+  synthetic?: boolean
+  renderCache?: RenderCache
+}